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tripath technology, inc. - technical information 1 TA2022 ? kli/1.0/11-01 TA2022 stereo 90w (4 ? ) class-t? digital audio amplifier driver using digital power processing (dpp?) technology technical information revision 1.0 ? november 2001 general description the TA2022 is a 90w (4 ? ) continuous average per channel class-t digital audio power amplifier ic using tripath?s pr oprietary digital power processing (dpp tm ) technology. class-t amplifiers offer bot h the audio fidelity of class-ab and the power efficiency of class-d amplifiers. applications dvd players mini/micro component systems home theater powered speakers benefits fully integrated solution with internal fets dramatically improves efficiency versus class-ab amplifiers signal fidelity equal to high quality linear amplifiers high dynamic range compatible with digital media such as cd and dvd features class-t architecture high power 100w @ 4 ? , 1.0% thd+n 90w @ 4 ? , 0.1% thd+n 60w @ 8 ? , 0.1% thd+n ?audiophile? sound quality 0.015% thd+n @ 70w 4 ? 0.015% thd+n @ 45w 8 ? 0.10% ihf-im @ 25w 4 ? high efficiency 92% @ 88w 8 ? 87% @ 125w 4 ? dynamic range = 102 db mute input integrated gate drive supply over-current protection over and under-voltage protection single ended outputs outputs can be operated in bridged mode 32-pin ssip package
tripath technology, inc. - technical information 2 TA2022 ? kli/1.0/11-01 absolute maximum ratings (note 1) symbol parameter value units vpp, vnn supply voltage (vpp1, vpp2, vnn1, vnn2) +/- 40 v v5 positive 5v bias supply voltage at input pins (pins 18, 19, 23, 24, 26, 28-32) 6 -0.3v to (v5+0.3v) v v vn10 voltage for low-side fet drive vnn+13 v t store storage temperature range -55o to 150o c t a operating free-air temperature range (note 2) -40o to 85o c t j junction temperature 150o c esd hb esd susceptibility ? human body model (note 3) all pins (except pin 27) pin 27 4000 1500 v v esd mm esd susceptibility ? machine model (note 4) all pins 200 v note 1: absolute maximum rati ngs indicate limits beyond which damage to the device may occur. see the table below for operating conditions. note 2: this is a target specification. characte rization is still needed to validat e this temperature range. note 3: human body model, 100pf discharged through a 1.5k ? resistor. note 4: machine model, 220pf ? 240pf discharged through all pins. operating conditions (note 5) symbol parameter min. typ. max. units vpp, vnn supply voltage (vpp1, vpp2, vnn1, vnn2) +/- 12 +/-31 +/- 36 v v5 positive 5 v bias supply 4.5 5 5.5 v vn10 voltage for fet drive (volts above vnn) 9 11 12 v note 5: recommended operating conditions indicate conditions for which the device is functional. see electrical characteristics for guaranteed specific per formance limits. thermal characteristics symbol parameter value units jc junction-to-case thermal resistance 1.0 c/w ja junction-to-ambient thermal resistance (still air) 20 c/w
tripath technology, inc. - technical information 3 TA2022 ? kli/1.0/11-01 electrical characteristics (notes 6, 7) t a = 25 c. see application/test circuit on page 8. unless otherwise noted, the supply voltage is vpp=|vnn|=31v. symbol parameter conditions min. typ. max. units i q quiescent current (no load, mute = 0v) vpp = +31v vnn = -31v (note 8) v5 = 5v (note 9) vn10 = 11v (note 10) 20 55 45 65 60 80 ma ma ma ma i mute mute supply current (no load, mute = 5v) vpp = +31v vnn = -31v (note 8) v5 = 5v (note 9) 0.5 2 20 25 ma ma ma v ih high-level input voltage (mute) i ih = see mute control section 3.5 v v il low-level input voltage (mute) i il = see mute control section 1.0 v v oh high-level output voltage (hmute) i oh = 3ma 4.0 v v ol low-level output voltage (hmute) i ol = 3ma 0.5 v v offset output offset voltage no load, mute = logic low 0.1% r fba , r fbb , r fbc resistors -750 750 mv i oc over current sense threshold tbd 7 8 a i vppsense vppsense threshold currents over-voltage turn on (muted) over-voltage turn off (mute off) under-voltage turn off (mute off) under-voltage turn on (muted) 138 62 162 154 79 72 178 87 a a a a v vppsense threshold voltages with r vppsense = 249k ? (note 11, note 12) over-voltage turn on (muted) over-voltage turn off (mute off) under-voltage turn off (mute off) under-voltage turn on (muted) 36.5 17.8 42.8 40.9 22.2 20.4 47.3 24.4 v v v v i vnnsense vnnsense threshold currents over-voltage turn on (muted) over-voltage turn off (mute off) under-voltage turn off (mute off) under-voltage turn on (muted) 152 65 174 169 86 77 191 95 a a a a v vnnsense threshold voltages with r vnnsense = 249k ? (note 11, note 12) over-voltage turn on (muted) over-voltage turn off (mute off) under-voltage turn off (mute off) under-voltage turn on (muted) -36.2 -14.8 -42.1 -40.8 -20.2 -17.9 -46.8 -22.6 v v v v
tripath technology, inc. - technical information 4 TA2022 ? kli/1.0/11-01 performance characteristics ? single ended (notes 6, 7) t a = 25 c. unless otherwise noted, the supply voltage is vpp=|vnn|=31v, the input frequency is 1khz and the measurement bandwidth is 20khz . see application/test circuit on page 8. symbol parameter conditions min. typ. max. units p out output power (continuous average/channel) (note 13) vpp = |vnn| = +/-31v, r l = 4 ? thd+n = 0.1% thd+n = 1.0% thd+n = 10% vpp = |vnn| = +/-35v, r l = 8 ? thd+n = 0.1% thd+n = 10% 80 90 100 125 60 88 w w w w thd + n total harmonic distortion plus noise p out = 70w/channel, r l = 4 ? vpp = |vnn| = +/-31v p out = 45w/channel, r l = 8 ? vpp = |vnn| = +/-35v 0.015 0.015 % % ihf-im ihf intermodulation distortion 19khz, 20khz, 1:1 (ihf), r l = 4 ? p out = 25w/channel 0.1 % snr signal-to-noise ratio a-weighted 0db = 90w/channel, r l = 4 ? 102 db cs channel separation 0db = 25w, r l = 4 ? 83 db a v amplifier gain p out = 10w/channel, r l = 4 ? , see application / test circuit 18.1 v/v a verror channel to channel gain error p out = 10w/channel, r l = 4 ? see application / test circuit 0.5 db power efficiency p out = 88w/channel, r l = 8 ? p out = 125w/channel, r l = 4 ? 92 87 % % i sload source current p out = 125w/channel, r l = 4 ? vpp = +31v vnn = -31v v5 = 5v 4.59 4.61 45 a a ma e nout output noise voltage a-weighted, input ac grounded 150 v performance characteristics ? bridged tied load (notes 6, 7) t a = 25 c. unless otherwise noted, the supply voltage is vpp=|vnn|=30v, the input frequency is 1khz and the measurem ent bandwidth is 20khz. symbol parameter conditions min. typ. max. units p out output power (continuous average) (note 13) vpp = |vnn| = +/-30v, r l = 8 ? thd+n = 0.1% thd+n = 10% 150 235 w w thd + n total harmonic distortion plus noise p out = 100w, r l = 8 ? 0.05 % ihf-im ihf intermodulation distortion 19khz, 20khz, 1:1 (ihf), r l = 8 ? p out = 25w 0.10 % power efficiency p out = 225w, r l = 8 ? 87 % snr signal-to-noise ratio a-weighted, r l = 8 ? 0db = 150w 104 db e nout output noise voltage a-weighted, input ac grounded 220 v note 6: minimum and maximum limits are guaranteed but may not be 100% tested. note 7: for operation in ambient temperatures greater than 25 c, the device must be derated based on the maximum junction temperatur e and the thermal resistance determined by the mounting technique.
tripath technology, inc. - technical information 5 TA2022 ? kli/1.0/11-01 note 8: this specification includes the current draw from the internal buck regulator. if an external floating supply is used, instead of the internal buck regulator, the quiescent current draw of the vnn supply will be approximately 20ma. note 9: this specification includes the curr ent draw from both the TA2022 and the external feedback biasing. note 10: this is the current draw of the vn10 pin if an external ?floating? 11v supply is used instead of the internal buck regulator note 11: these supply voltages are ca lculated using the ivppsense and ivnnsense values shown in the electrical characteri stics table. the typical voltage values shown are calculated using a r vppsense and rvnnsense value of 249kohm without any tolerance variation. t he minimum and maximum voltage limits shown include either a +1% or ?1% (+1% for ov er-voltage turn on and under-voltage turn off, -1% for over-voltage turn off and under-voltage turn on) variation of rvppsense or rvnnsense off the nominal 249kohm value. these voltage specifications are examples to show bot h typical and worst case voltage ranges for a given rvppsense and rvnnsense resistor va lue of 249kohm. please refer to the application information section for a mo re detailed description of how to calculate the over and under voltage trip voltages for a given resistor value. note 12: the fact that the ov er-voltage turn on and over-voltage turn off specifications exceed the absolute maximum of +/-40v for the ta 2022 does not imply that the part will work at these elevated supply voltages. it also does not imply that TA2022 is tested or guaranteed at these supply voltages. the s upply voltages are simply a calculation based on the process spread of the i vppsense and i vnnsense currents (see note 11). the supply voltage must be maintained below the absolute maximum of +/-40v or permanent damage to the TA2022 may occur. note 13: the supply voltage limitation for 4 ohm single ended (+/-31v), or 8 ohm bridged (+/- 30v), is based on the current limit protection ci rcuitry. the current limit circuitry may be activated during large output excurs ions if the recommended supply voltage ranges are exceeded. this will result in the amplifier being muted.
tripath technology, inc. - technical information 6 TA2022 ? kli/1.0/11-01 TA2022 pinout pin description pin function description 1, 13 vboot2, vboot1 bootstrap voltages for gate drive of high side mosfet?s 2 vn10 ?floating? supply input. normally connected to the output of onboard vn10 buck converter. this voltage must be stable and referenced to vnn. 3 vn10gnd power ground for onboard vn10 generator. electrically tied to the TA2022 case. 4, 12 vpp2, vpp1 positive power supply input pins. 5 vn10sw switching output voltage for onboard vn10 generator (buck converter). 6 nc not connected internally. may be connected to pin 7 without any loss of functionality or performance. 7,10 out2, out1 power amplifier outputs. 8, 9 vnn2, vnn1 negative power supply inputs. 11 nc not connected internally. may be connected to pin 10 without any loss of functionality or performance. 14 vn10fdbk feedback for onboard vn10 generat or (nominally 11v above vnn) 15, 20 agnd analog ground. 16, 21 v5 5v power supply input. 17 ref used to set internal bias current s. the pin voltage is typically 1.1v. 18 vnnsense negative supply voltage sense input. this pin is used for both over and under voltage sensing for the vnn supply. 19 vppsense positive supply voltage sense input. this pin is used for both over and under voltage sensing for the vpp supply. 22, 25 oaout1, oaout2 outputs of input stage op amps. 23, 26 inv1, inv2 inverting inputs of input stage op amps. 24 mute logic input. a logic high puts the amplifie r in mute mode. ground pin if not used. please refer to the section, mute control, in the application information. 27 biascap bandgap reference times two (typically 2.5vdc). used to set the common mode voltage for the input op amps. this pin is not capable of driving external circuitry. 28, 29 fbkgnd2, fbkout2 output volt age differential feedback for channel 2. 30,31 fbkgnd1, fbkout1 output voltage differential feedback for channel 1. 32 hmute logic output. a logic high indicates both amplifiers are muted, due to the mute pin state, or a ?fault? such as an overcurrent, undervoltage, or overvoltage condition. fbkgnd1 agnd vnnsense vppsense agnd v5 oaout1 inv1 mute oaout2 inv2 vboot2 biascap fbkgnd2 fbkout2 fbkout1 v5 vn10fdbk vboot1 vpp1 nc out1 vnn1 vnn2 out2 nc vpp2 vn10gnd vn10 hmute 30 16 17 18 19 20 21 22 23 24 25 26 27 28 29 1 15 14 13 11 10 12 9 8 7 6 5 4 3 2 32-pin ssip package (front view) 32 31 ref vn10sw
tripath technology, inc. - technical information 7 TA2022 ? kli/1.0/11-01 application /test circuit TA2022 r l 4 ? or 8 ? hmute oaout1 inv1 out1 c i 3.3uf 22 23 32 10 + vpp1 vnn1 processing & modulation c o 0.22uf l o 10uh, 10a analog ground power ground (pin 9) r f 20k ? r i 20k ? c z 0.22uf r z 6.2 ?, 2w c b 0.1uf c baux 47uf vboot1 13 r b 250 ? vnn1 vn10 d b 11dq09 vn10 fbkout1 31 fbkgnd1 30 r fba 1k ? *r fbb 1.1k ? *r fbb 1.1k ? r fba 1k ? d o mur120 *r fbc 9.1k ? *r fbc 9.1k ? v5 (pin 21) agnd (pin 20) + v5 agnd c fb 390pf c s 0.1uf c s 0.1uf 21 20 v5 15 agnd agnd v5 16 5v oaout2 inv2 out2 c i 3.3uf 25 26 7 + vpp2 vnn2 processing & modulation c o 0.22uf l o 10uh, 10a (pin 8) r f 20k ? r i 20k ? c z 0.22uf r z 6.2 ?, 2w c b 0.1uf c baux 47uf vboot2 1 r b 250 ? vnn2 vn10 d b 11dq09 vn10 fbkout2 29 fbkgnd2 28 r fba 1k ? *r fbb 1.1k ? *r fbb 1.1k ? r fba 1k ? d o mur120 *r fbc 9.1k ? *r fbc 9.1k ? v5 (pin 21) + - + v5 agnd c fb 560pf mute 24 5v v5 biascap c a 0.1uf 27 17 ref r ref 8.25k ?, 1% 12 vpp1 9 vnn1 + c hbr 0.1uf,100v cs 220uf, 50v c s 0.1uf, 50v + cs 220uf, 50v c s 0.1uf, 50v 8 vnn2 4 vpp2 c hbr 0.1uf,100v vpp vnn vn10gnd *r vppsense(vpp1) vpp vnn 19 vppsense 18 vnnsense 3 vn10 generator vnn agnd (pin 20) vn10sw 5 c swfb 0.1uf,50v vn10fbk 14 vnn c sw 0.1uf,35v vn10 2 vnn d sw 11dq09 l sw 100uh, 1a r swfb 1k ? + c sw 100uf, 35v vn10 r l 4 ? or 8 ? 2.5v 200k ? (pin 20) (pin 20) (pin 20) r ofa 50k ? r ofb 10k ? to fbkgnd1 (pin30) offset trim circuit v5 (pin 21) agnd (pin 20) vnn 249k ?, 1% r ofa 50k ? r ofb 10k ? to fbkgnd2 (pin28) offset trim circuit v5 (pin 21) agnd (pin 20) - + *r vnnsense(vnn1) 249k ?, 1% 6 nc 11 nc *r vpp2 v5 v5 *r vnn2 optional components - see application information * the values of these components must be adjusted based on supply voltage range. see application information. vpp2 (pin 4) d o mur120 vpp1 (pin 12) d o mur120 application / test diagram c s 0.1uf, 50v c s 0.1uf, 50v c s 0.1uf, 50v c s 0.1uf, 50v
tripath technology, inc. - technical information 8 TA2022 ? kli/1.0/11-01 external components description (refer to the application/test circuit) components description r i inverting input resistance to provide ac gain in conjunction with r f . this input is biased at the biascap voltage (approximately 2.5vdc). r f feedback resistor to set ac gain in conjunction with r i . please refer to the amplifier gain paragraph, in the application information section. c i ac input coupling capacitor which, in conjunction with r i , forms a high pass filter at ) c r 2 ( 1 f i i c = . r fba feedback divider resistor connected to v5. this resistor is normally set at 1k ? . r fbb feedback divider resistor connected to agnd. this value of this resistor depends on the supply voltage setting and helps set the TA2022 gain in conjunction with r i, r f, r fba, and r fbc . please see the modulator feedback design paragraphs in the application information section. r fbc feedback resistor connected from either t he out1(out2) to fbkout1(fbkout2) or speaker ground to fbkgnd1(fbkgnd2). the value of this resistor depends on the supply voltage setting and helps set the TA2022 gain in conjunction with r i, r f, r fba, , and r fbb . it should be noted that the resistor from out1(out2) to fbkout1(fbkout2) must have a power rating of greater than ) (2r vpp p fbc 2 diss = . please see the modulator feedback design paragraphs in the application information section. c fb feedback delay capacitor that both lowers the idle switching frequency and filters very high frequency noise from the feedback signal, which improves amplifier performance. the value of c fb should be offset between channel 1 and channel 2 so that the idle switching difference is greater than 40khz. please refer to the application / test circuit. r ofa potentiometer used to manually trim the dc offset on the output of the TA2022. r ofb resistor that limits the manual dc offset trim range and allows for more precise adjustment. r ref bias resistor. locate close to pin 17 and ground at pin 20. c a biascap decoupling capacitor. should be located close to pin 27 and grounded at pin 20. d b bootstrap diode. this diode charges up the bootstrap capacitors when the output is low (at vnn) to drive the high side gate circuitry. schottky or fast recovery diode rated at least 200ma, 90v, 50ns is recommended for the bootstrap circuitry. in addition, the bootstrap diode must be able to sustain the entire vpp-vnn voltage. thus, for most applications, a 90v (or greater) diode should be used. c b high frequency bootstrap capacitor, which filters the high side gate drive supply. this capacitor must be located as close to pin 13 (vboot1) or pin1n (vboot2) for reliable operation. the other side of c b should be connected directly to the out1 (pin 10) or out2 (pin 7). please refer to the application / test circuit. c baux bulk bootstrap capacitor that supplements c b during ?clipping? events, which result in a reduction in the average switching frequency. r b bootstrap resistor that limits c baux charging current during TA2022 power up (bootstrap supply charging). c sw vn10 generator filter capacitors. the high frequency capacitor (0.1uf) must be located close to pin 2 (vn10) to maximize device performance. the value of the bulk capacitor should be sized appropriately such that the vn10 voltage does not overshoot with respect to vnn during TA2022 turn on. tripath recommends using a value of 100f for the bulk capacitor. l sw vn10 g enerator filter inductor. this inductor sized a pp ro p riatel y so that l s w does not
tripath technology, inc. - technical information 9 TA2022 ? kli/1.0/11-01 saturate. if the recommended inductor value of 100h is not used, the vn10 may overshoot with respect to vnn during TA2022 turn on. d sw flywheel diode for the internal vn10 buck converter. this diode also prevents vn10sw from going more than one diode drop negative with respect to vnn. this diode can be a fast recovery, switching or shottky, but must be rated at least 200ma, 30v, 50ns. c swfb vn10 generator feedback capacitor. this capacitor, in conjunction with r swfb , filters the vn10 feedback signal such that the loop is unconditionally stable. r swfb vn10 generator feedback resistor. this resistor sets the nominal vn10 voltage. with r swfb equal to 1k ? , the internally vn10 voltage will typically be 11v above vnn. c s supply decoupling for the power supply pins. for optimum performance, these components should be located close to the TA2022 and returned to their respective ground as shown in the application/test circuit. r vnnsnese overvoltage and undervoltage sense resistor for the negative supply (vnn). please refer to the electrical characteristics section for the trip points as well as the hysteresis band. also, please refer to the over / under-voltage protection section in the application information for a detailed discussion of the internal circuit operation and external component selection. r vppsense overvoltage and undervoltage sense resistor for the positive supply (vpp). please refer to the electrical characteristics section for the trip points as well as the hysteresis band. also, please refer to the over / under-voltage protection section in the application information for a detailed discussion of the internal circuit operation and external component selection. c hbr supply decoupling for the high current half-bridge supply pins. these components must be located as close to the device as possible to minimize supply overshoot and maximize device reliability. these capacitors should have good high frequency performance including low esr and low esl. in addition, the capacitor voltage rating must be twice the maximum vpp voltage. c z zobel capacitor, which in conjunction with r z , terminates the output filter at high frequencies. use a high quality film capacitor capable of sustaining the ripple current caused by the switching outputs. r z zobel resistor, which in conjunction with c z , terminates the output filter at high frequencies. the combination of r z and c z minimizes peaking of the output filter under both no load conditions or with real world loads, including loudspeakers which usually exhibit a rising impedance with increasing frequency. the recommended power rating is 2 watts. d o fast recovery diodes that minimize overs hoots and undershoots of the outputs with respect to power ground during switching transitions as well as output shorts to ground. for maximum effectiveness, these diodes must be lo cated close to the output pins and returned to their respective vpp and vnn. also, they should be rated with a maximum forward voltage of 1v at 10a. please see a pplication/test circuit for vpp and vnn return pins. l o output inductor, which in conjunction with c o , demodulates (filters) the switching waveform into an audio signal. forms a se cond order filter with a cutoff frequency of ) c l 2 ( 1 f o o c = and a quality factor of o o o l c l c r q = . these inductors must be rated at least 10a with high linearity. please see output filter design section for details. c o output capacitor, which, in conjunction with l o , demodulates (filters) the switching waveform into an audio signal. forms a second order low-pass filter with a cutoff frequency of ) c l 2 ( 1 f o o c = and a quality factor of o o o l c l c r q = . use a high quality film capacitor capable of sustaining the ripple current caused by the switching outputs. electrolytic capacitors should not be used.
tripath technology, inc. - technical information 10 TA2022 ? kli/1.0/11-01 typical performance characteristics ? single ended 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 2 100 5 10 20 50 output power (w) thd+n (%) thd+n vs output power f = 1khz rl= 8 ? vpp=|vnn|=35v aes 17 filter 1 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) thd+n (%) thd+n vs frequency po = 25w/ch rl = 8 ? vpp=|vnn|=35v bw = 22khz bw = 30khz 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) thd+n (%) thd+n vs frequency po = 50w/ch rl = 4 ? vpp=|vnn|=31v bw = 22khz bw = 30khz 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 1 200 2 5 10 20 50 100 output power (w) thd+n (%) thd+n vs output power f = 1khz rl= 4 ? vpp=|vnn|=31v aes 17 filter -140 +0 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) amplitude (dbr) intermodulation distortion 19khz, 20khz 1:1 po = 25w/ch, 4 ? 0dbr = 10.0vrms vpp=|vnn|=31v bw = 22hz - 30khz -140 +0 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) amplitude (dbr) intermodulation distortion 19khz, 20khz 1:1 po = 12.5w/ch, 8 ? 0dbr = 10.0vrms vpp=|vnn|=31v bw = 22hz - 30khz
tripath technology, inc. - technical information 11 TA2022 ? kli/1.0/11-01 typical performance characteristics ? single ended ty 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 2 100 5 10 20 50 output power (w) thd+n (%) thd+n vs output power f = 1khz rl= 8 ? aes 17 filter 1 +/-25v +/-30v +/-35v -100 -40 -95 -90 -85 -80 -75 -70 -65 -60 -55 -50 -45 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) channel separation (dbr) channel separation vpp=|vnn|=31v po = 25w/ch, 4 ? po = 12.5w/ch, 8 ? bw = 22hz - 22khz rl = 8 ? rl = 4 ? -120 -70 -115 -110 -105 -100 -95 -90 -85 -80 -75 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) amplitude (dbr) noise floor vpp=|vnn|=31v rf=ri=20k ? 16kfft aes 17 filter 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 1 200 2 5 10 20 50 100 output power (w) thd+n (%) thd+n vs output power f = 1khz rl= 4 ? aes 17 filter +/-23v +/-27v +/-31v 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 110 120 output power (w) efficiency (%) vpp=|vnn|=31v rl = 4 ? aes 17 filter thd+n < 10% efficiency vs output power 0 10 20 30 40 50 60 70 80 90 100 0 102030405060708090 output power (w) efficiency (%) vpp=|vnn|=35v rl = 8 ? aes 17 filter thd+n < 10% efficiency vs output power
tripath technology, inc. - technical information 12 TA2022 ? kli/1.0/11-01 typical performance characteristics ? bridged -140 +0 -130 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) amplitude (dbr) intermodulation distortion 19khz, 20khz 1:1 po = 50w/ch, 8 ? bridged 0dbr = 20.0vrms vpp=|vnn|=30v bw = 22hz - 30khz 2 300 5 10 20 50 100 200 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 output power (w) thd+n (%) thd+n vs output power f = 1khz rl= 8 ? bridged aes 17 filter 1 +/-23v +/-27v +/-30v 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) thd+n (%) thd+n vs frequency po = 100w/ch rl = 8 ? bridged vpp=|vnn|=30v bw = 22khz bw = 30khz -120 -70 -115 -110 -105 -100 -95 -90 -85 -80 -75 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) amplitude (dbr) noise floor vpp=|vnn|=30v rf=ri=20k ? 8 ? bridged 16kfft aes 17 filter 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 140 160 180 200 220 240 output power (w) efficiency (%) vpp=|vnn|=30v rl = 8 ? bridged aes 17 filter thd+n < 10% efficiency vs output power 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 2 300 5 10 20 50 100 200 1 output power (w) thd+n (%) f = 1khz vpp=|vnn|=30v rl= 8 ? bridged aes 17 filter thd+n vs output power
tripath technology, inc. - technical information 13 TA2022 ? kli/1.0/11-01 application information TA2022 basic amplifier operation the TA2022 has three major operational blocks: the signal processor, the mosfet driver, and the power mosfets. the signal processor is a 5v cm os block that amplifie s the audio input signal and converts the audio signal to a switching pattern. th is switching pattern is spread spectrum with a typical idle switching frequency of about 650khz. t he switching patterns for the two channels are not synchronized and the idle switching frequencies should differ by at least 40khz to avoid increasing the audio band noise floor. the idle frequency differ ence can be accomplished by offsetting the value of c fb for each channel. typical values of c fb are 390pf for channel 1 and 560pf for channel 2. the mosfet driver level-shifts the signal proce ssor?s 5v switching patterns to the power supply voltages and drives the power mosfets. the mo sfet driver includes a switching power supply integrated to generate the vn10 supply. the vn10 supply powers the low side gate drivers as well provides the charging current need for the ?boot strapped? supplies (vboot1 and vboot2) that power the high side mosfet drivers. vn10 must be stable (regulated) at 10v to 12v above vnn. the vn10 circuitry shown in the application / test circuit typically produces 11v above vnn. the power mosfets are n-channel devices configur ed in half-bridges and are used to supply power to the output load. the outputs of the power mosfets (out1 and out2) must be low pass filtered to remove the high frequency switching pattern. a residual voltage from the switching pattern will remain on the speaker outputs when the recommended out put lc filter is used, but this signal is outside of the audio band and will not affect audio performance. circuit board layout the TA2022 is a power (high current) amplifier that operates at relatively high switching frequencies. the output of the amplifier sw itches between vpp and vnn at high speeds while driving large currents. this high-frequency digital signal is pa ssed through an lc low-pass filter to recover the amplified audio signal. since the amplifier must driv e the inductive lc output filter and speaker loads, the amplifier outputs can be pulled above the suppl y voltage and below ground by the energy in the output inductance. to avoid subjecting the TA2022 to potentially damaging voltage st ress, it is critical to have a good printed circuit board layout. it is recommended that tripath? s layout and application circuit be used for all applications and only be deviated fr om after careful analysis of the effects of any changes. please refer to the TA2022 evaluati on board document, eb-TA2022, available on the tripath website, at www.tripath.com. the following components are important to place near their associated TA2022 pins and are ranked in order of layout importance, either for pr oper device operation or per formance considerations. - the capacitors c hbr provide high frequency bypassing of the amplifier power supplies and will serve to reduce spikes across the supply rails. c hbr should be kept within 1/8? (3mm) of the vnn(8,9) and vpp(4,12) pins. pleas e note that both vnn1 and vpp1 as well as vnn2 and vpp2 must be decoupled separately. in addition, the voltage rating for c hbr should be 100v as this capacitor is ex posed to the full supply range, vpp-vnn. - d o , fast recovery pn junction diodes minimize undershoots of the outputs with respect to power ground during switching transitions and abnormal load conditions such as output shorts to ground. for maximum effectiveness, these diodes must be located close to the output pins and returned to their respective v nn1(2). please see application/test circuit for ground return pin. - c fb removes very high frequency components from the amplifier feedback signals and lowers the output switching frequency by delay ing the feedback signals. in addition, the value of c fb is different for channel 1 and channel 2 to keep the average switching frequency difference greater than 40khz. this minimizes in-band audio noise.
tripath technology, inc. - technical information 14 TA2022 ? kli/1.0/11-01 - to minimize noise pickup and minimize thd+n, r fbc should be located as close to the TA2022 as possible. make sure that the rout ing of the high voltage feedback lines is kept far away from the input op amps or significant noise coupling may occur. it is best to shield the high voltage feedback lines by using a gr ound plane around these traces as well as the input section. - c b provides high frequency bypassing for the boot strap supplies. very high currents are present on these supplies. - c sw provides high frequency bypassing for the vn 10 generator circuit. very high currents are present on these supplies. - c swfb filters the feedback signal (vn10fdbk) for the hysteretic vn10 buck converter. the feedback signal is noise sensitive and the trace from c swfb to vnn should be kept short. - d sw is the flywheel diode for the vn10 buck c onverter and prevents vn10sw(pin 5) from going more than one diode drop below vnn. in general, to enable placement as close to the ta 2022, and minimize pcb parasitics, the capacitors listed above should be surface mount types, lo cated on the ?solder? side of the board. some components are not sensitive to location but ar e very sensitive to layout and trace routing. - to maximize the damping factor and reduce distortion and noise, the modulator feedback connections should be routed directly to the pins of the output inductors, l o . this was done on the eb-TA2022 board. - the output filter capacitor, c o , and zobel capacitor, c z , should be star connected with the load return. the output ground feedback signal should be taken from this star point. this is suggested by the routing on the application/test schematic, bu t, for space/layout reasons, this was not fully implemented on the eb-2022. - the modulator feedback resistors, r fba and r fbb should all be grounded and attached to 5v together. these connections will serve to minimize common mode noise via the differential feedback. please refer to the eb- TA2022 evaluation board for more information. TA2022 grounding proper grounding techniques are required to ma ximize TA2022 functionality and performance. parametric parameters such as thd+n, noise floor and crosstalk can be adversely affected if proper grounding techniques are not implemented on the pc b layout. the following discussion highlights some recommendations about grounding both with re spect to the TA2022 as well as general ?audio system? design rules. the TA2022 is divided into two sections: the input section, which spans pin 15 through pin 32, and the output (high power) section, which spans pin 1 through pin 14. on the TA2022 evaluation board, the ground is also divided into distinct sections, one for the input and one for the output. to minimize ground loops and keep the audio noise floor as low as possible, the input and output ground must be only connected at a single point. depending on the system design, the single point connection may be in the form of a ferrite bead or a pcb trace. the analog grounds, pin 15 and pin 20 must be connec ted locally at the TA2022 for proper device functionality. on the TA2022 ev aluation board, tripath has used an analog ground plane to minimize the impedances between pin 15 and pin 20 as well as the other analog ground connections, such as v5 supply bypassing, and feedback divider networks. the ground for the v5 power supply should connect directly to pin 20. additionally, any external i nput circuitry such as preamps, or active filters, should be referenced to pin 20.
tripath technology, inc. - technical information 15 TA2022 ? kli/1.0/11-01 for the power section, tripath has traditionally used a ?star? grounding scheme. thus, the load ground returns and the power supply decoupling trac es are routed separately back to the power supply. in addition, any type of shield or c hassis connection would be connected directly to the ground star located at the power supply. thes e precautions will both minimize audible noise and enhance the crosstalk performance of the TA2022. the TA2022 incorporates a differential feedback sy stem to minimize the effects of ground bounce and cancel out common mode ground noise. as su ch, the feedback from the output ground for each channel needs to be properly sensed. this c an be accomplished by connecting the output ground ?sensing? trace directly to the star formed by the output ground return, output capacitor, c o , and the zobel capacitor, c z . refer to the application / test circuit for a schematic description. pin 3, vn10gnd, is used for the vn10 buck converte r. pin 3 can be connected to the main power supply decoupling ground trace (or plane) without any loss in functionality or reduction of performance. this pin is electric ally shorted to the copper heat sink (case) of the TA2022. even if the internal vn10 regulator is not being us ed, vn10gnd should still be connected to pgnd. TA2022 amplifier gain the gain of the TA2022 is the product of the input stage gain and the modulator gain. please refer to the sections, input stage design, and modulator f eedback design, for a complete explanation of how to determine the external component values. modulator v e vinputstag vTA2022 a * a a = ? ? ? ? ? ? + + ? 1 r * r ) r (r * r r r a fbb fba fbb fba fbc i f vTA2022 for example, using a TA2022 with the following external components, r i = 20k ? r f = 20k ? r fba = 1k ? r fbb = 1.13k ? r fbc = 9.09k ? v v 18.13 1 1.13k ? * 1.0k ? ) 1.13k (1.0k ? * 9.09k ? 20k ? 20k ? a vTA2022 = ? ? ? ? ? ? + ? + ? input stage design the TA2022 input stage is configured as an inverting am plifier, allowing the system designer flexibility in setting the input stage gain and frequency response. figure 1 shows a typical application where the input stage is a constant gain inverting amplifier. the input stage gain should be set so that the maximum input signal level will driv e the input stage output to 4vpp.
tripath technology, inc. - technical information 16 TA2022 ? kli/1.0/11-01 TA2022 2 input2 oaout2 v5 oaout1 + - ci + - inv1 input1 biascap agnd rf ri ci rf a gnd inv2 v5 ri figure 1: input stage the gain of the input stage, above t he low frequency high pass filter point, is that of a simple inverting amplifier: it should be noted that the input opamps are biased at approximately 2.5vdc. thus, the polarity of c i must be followed as shown in figure 1 for a standard ground referenced input signal i f e vinputstag r r a ? = input capacitor selection c i can be calculated once a value for r i has been determined. c i and r i determine the input low frequency pole. typically this pole is set below 10hz. c i is calculated according to: i p i r f 2 1 c = where: i r = input resistor value in ohms. p f = input low frequency pole (typically 10hz or below). modulator feedback design the modulator converts the signal from the i nput stage to the high-voltage output signal. the optimum gain of the modulator is determined from the maximum allowable feedback level for the modulator and maximum supply voltages for the power stage. depending on the maximum supply voltage, the feedback ratio will need to be adjusted to maximize performance. the values of r fba , r fbb and r fbc (see explanation below) define the gain of the modulator. once these values are chosen, based on the maximum supply voltage, the gai n of the modulator will be fixed even with as the supply voltage fluctuates due to current draw. for the best signal-to-noise ratio and lowest di stortion, the maximum modulator feedback voltage should be approximately 4vpp. this will keep the gai n of the modulator as low as possible and still allow headroom so that the feedback signal does not clip the modulator feedback stage. figure 2 shows how the feedback from the output of the amplifier is returned to the input of the modulator. the input to the modulator (fbkout 1/fbkgnd1 for channel 1) can be viewed as inputs to an inverting differential amplifier. r fba and r fbb bias the feedback signal to approximately 2.5v and r fbc scales the large out1/out2 signal to down to 4vpp.
tripath technology, inc. - technical information 17 TA2022 ? kli/1.0/11-01 out 1 ground rfbb fbkgnd1 rfba out1 rfbc v5 rfbc fbkout1 rfbb rfba agnd 1/2 TA2022 processing modulation & figure 2: modulator feedback the modulator feedback resistors are: ? = 1k typically specified, user r fba 4) - (vpp vpp * r r fba fbb = 4 vpp * r r fba fbc = 1 r * r ) r (r * r a fbb fba fbb fba fbc modulator - v + + the above equations assume that vpp=|vnn|. for example, in a system with vpp max =36v and vnn max =-36v, r fba = 1k ? , 1% r fbb = 1.125k ? , use 1.13k ? , 1% r fbc = 9.0k ? , use 9.09k ? , 1% the resultant modulator gain is: 18.13v/v 1 1.13k ? * 1.0k ? ) 1.13k (1.0k ? * 9.09k ? a modulator - v = + ? +
tripath technology, inc. - technical information 18 TA2022 ? kli/1.0/11-01 mute the mute pin must be driven to a logic low or logi c high state for proper operat ion. the state of the mute pin is ?latched in? to minimize the effects of noise on this pin, which could cause the TA2022 to switch state unintentionally. contro lling the mute pin with a push-pull output from a microcontroller, or a physical switch between v5 and agnd, works well as both solutions have low impedance drive capability. in some cases, it may be desirable to drive the mute pin with an alternative approach. when the device is in mute, the pin must be ?pull ed low? via approximately 1kohm to overcome the internal latch and change the TA2022 state (i.e. out of mute). when the device is not in mute, the mute pin must be ?pulled high? via approximately 2kohm to overcome the internal latch and change the TA2022 state (i.e. into mute). figure 3 shows a si mple control circuit that buffers a mute control signal that is not capable of driv ing the mute pin of the TA2022 dire ctly. when the mute control signal is high, the mute pin will be driven low and the ta 2022 will be on. if the mute control signal is low, the 2k resistor will pull the mute pin high and the TA2022 will be muted. figure 3: low impedance drive for mute pin to ensure proper device operation, including minimizati on of turn on/off transients that can result in undesirable audio artifacts, tripath recommends t hat the TA2022 device be muted prior to power up or power down of the 5v supply. the ?sensing? of the v5 supply can be easily accomplished by using a ?microcontroller supervisor? or equivalent to dr ive the TA2022 mute pin high when the v5 voltage is below 4.5v. this will ensure proper operation of the TA2022 input circuitry. a micro-controller supervisor such as the mcp101-450 from microc hip corporation has been used by tripath to implement clean power up/down operation. if turn-on and/or turn-off noise is still present with a TA2022 amplifier, the cause may be other circuitry external to the TA2022. while the TA2022 has circ uitry to suppress turn-on and turn-off transients, the combination of power supply and other audio circ uitry with the TA2022 in a particular application may exhibit audible transients. one solution that will completely eliminate turn-on and turn-off pops and clicks is to use a relay to connect/disconnect that amplifier from the speakers with the appropriate timing during power on/off. TA2022 output capability the TA2022 can output two channels at 100 watts eac h into a 4ohm load at 1% thd+n. the maximum amplifier output power is determined by a number of factors including the TA2022 junction temperature, the load impedance and the power supply voltage. tripath does not recommend driving loads below 4 ohm single ended as the amplifier efficiency will be seriously reduced and the amplifier may prematurely current limit. mute agnd to mute (pin 24) 2k control 10k v5
tripath technology, inc. - technical information 19 TA2022 ? kli/1.0/11-01 bridging the TA2022 the TA2022 can be bridged by returning the signal from oaout1 to the input resistor at inv2. out1 will then be a gained version of oaout1, and out2 will be a gained and inverted version of oaout1 (see figure 3). when the two amplif ier outputs are bridged, the apparent load impedance seen by each output is halved, so the mini mum recommended impedance for bridged operation is 8 ohms. due to the internal current limit setting, the maximum supply voltage recommended for bridged operation is +/-30v. bridged operation into loads below 8ohms is possible, but, as mentioned above, the amplifier efficiency will be reduced and the amplifier may prematurely current limit. the TA2022 is capable of 150w into 8 ohms bridged at 0.1% thd+n. agnd oaout2 v5 oaout1 agnd biascap v5 ri 20k ci inv1 rf TA2022 input inv2 + - + - 20k figure 4: input stage setup for bridging the switching outputs, out1 and out2, are not synchronized, so a common inductor may not be used with a bridged TA2022. for this same reas on, individual zobel networks must be applied to each output to load each output and lower the q of each common mode differential lc filter. output voltage offset the output offset voltage of the TA2022 is largely determined by the matching of the respective r fba , r fbb , and r fbc networks for fbkout1(fbkout2) and fbkgnd1 (fbkout2). thus, the intrinsic offset of the TA2022 can be altered by the external feedback network resistor matching. to minimize the nominal untrimmed offset voltage, 1% tolerance resistors are recommended. in most applications, the output offset voltage will need to be trimmed via an external circuit (either passive or active). the output offset voltage of the TA2022 can be nulled by modifying the modulator feedback as shown in figure 4. potentiometer r ofa is used to trim the effective resistance seen by the output ground, and therefore the output offset. rofb limits the trim range.
tripath technology, inc. - technical information 20 TA2022 ? kli/1.0/11-01 figure 5: manual output offset trim circuit a dc servo can also be used to automatically nu ll any offset voltage. the TA2022 evaluation board incorporates a dc servo. please refer to the TA2022 evaluation board document, eb-TA2022, available on the tripath website, at www.tripath.com . current protection design although the over-current (ioc) trip point is inter nally fixed, there are ex ternal components that can affect output current levels during a short circui t event. referring to the application/test diagram these include the output inductor (lo), output diodes (do) and supply bypassing (cs). the two output inductors, lo, directly impact t he peak output current levels reached during short circuit events. for this reason they must be rat ed at least 10a regardless of the systems maximum operating current, ensuring the inductor does not sa turate which could lead to switching currents passing unimpeded to the load. when this occurs, the ioc may be forced to trip on average current levels instead of peak current levels, directly impacting the current levels seen by the load and potentially causing damage to the TA2022. please refer to the output filter design section for more details on the inductor requirements and figure 6 fo r comparison of load currents with an unsaturated and saturated inductor. the four output diodes, do, minimize overshoots and undershoots with respect to the supply rails vpp and vnn. in order for these diodes to work properly they must have a low forward voltage rating at 10a. we recommend a fast recovery diode or ultra-fast pn rectifier diode with a vf rating of 1v at 10a, or better. also, these should be pl aced close to their respective output pins to maximum effectiveness. the two bulk supply voltage capacitors, cs, will absorb the current generated when the diodes (do) conduct. we recommend that a high frequency capac itor designed for low impedance and high ripple currents be used. tripath recommends an impedance of .1 ? or better at 100khz and a ripple current rating of 1arms at 100khz. for maximum effectivene ss, tripath recommends t hat these capacitors be placed close to their respective supply pins. rfbc 10k processing rfbb & out1 out 1 ground rfbb rfbc v5 fbkout1 agnd rfba rofb rofa 50k 1/2 TA2022 rfba fbkgnd1 modulation
tripath technology, inc. - technical information 21 TA2022 ? kli/1.0/11-01 figure 6: short circuit load current wi th unsaturated toroidal inductor and saturated bobbin inductor (shielded) output filter design tripath amplifiers generally have a higher swit ching frequency than pwm implementations allowing the use of higher cutoff frequency filters, reduc ing the load dependent peaking/drooping in the 20khz audio band. this is especially important for applic ations where the end customer may attach any speaker to the amplifier (as opposed to a system where speakers are shipped with the amplifier), since speakers are not purely resistive loads and the impedance they present changes over frequency and from speaker model to speaker model. an rc network, or ?zobel? (r z , c z ) must be placed at the filter output to control the im pedance ?seen? by the TA2022. the TA2022 works well with a 2 nd order, 107khz lc filter with l o = 10uh and c o = 0.22uf and r z = 6.2ohm/2w and c z = 0.22uf. some applications may require a more aggre ssive filter to reduce out of band noise. below are some proven filter combinations: - 49.5khz 2 nd order filter - 33.6khz 2 nd order filter l o = 22uh l o = 33uh c o = .47uf c o = .68uf r z = 8 ? r z = 6.2 ? c z = .47uf c z = .68uf - 65khz 4 th order filter l o1 = 15uh c o1 = 1uf l o2 = 10uh c o2 = .22uf r z = 10 ? c z = .47uf output inductor selection is a crit ical design step. the core materi al and geometry of the output filter inductor affects the TA2022 distortion levels, efficienc y, over-current protec tion, power dissipation and emi output. the inductor should have low loss at 700khz with 80vpp. it should be reiterated that regardless of the systems maximu m operating current, a 10a rating is required to ensure that peak current conditions will not cause the inductor to sa turate. during a short circuit event the inductor current increases very quickly in a saturated core (see figure 6), compromising the current protection scheme. a 10a rating is sufficient to ensure that current increases through the inductor are linear, and provides a safety margin for the TA2022. there are two types of inductors available in the 10a range that offers some emi containment: they are the toroidal type and the bobbin (shielded) type inductor. in bobbin construction, a ferrite shield is placed around the core of a bobbin inductor to help contain radiated emissions. this shield can reduce the amount of energy the inductor can store in the core by reducing the air gap, which can lower the peak curr ent capability of the inductor. typically, a 7-10a shielded bobbin inductor will not have the peak current capability necessary to ensure that the core
tripath technology, inc. - technical information 22 TA2022 ? kli/1.0/11-01 will not saturate during short circuit events; this is why they are not recommended for use with the TA2022. also it should be noted that shielded bobbin c onstruction is not as effective as toroidal construction for emi containment. tripath recommends that the customer use a toro idal inductor with a carbonyl-e core for all applications of the TA2022. this core has a high peak current capability due to its low- carbonyl-e metal powder. a distributed air gap increases its? ener gy storage capability, which allows for a small footprint and high current capability. carbonyl-e toroidal iron powder cores have low loss and good linearity. the toroidal shape is ideal for emi cont ainment. also, emi can be further contained by sizing the toroid to accept a full layer of windings. this aids in shielding the electric field. tripath recommends: - micrometals (www.micrometals. com) type-2 (carbonyl-e) toroidal iron powder cores. the specific core tripath initially verifi ed and used on the eb-TA2022 was a t94-2 (23.9mm outer diameter) wound to 11uh with 19awg wi re. since then tripath has determined that much smaller carbonyl-e toroids will not satu rate during high current events. tripath has also used t68-2 (17.5mm outer diameter) and the t60-2b/60(15.2mm outer diameter) cores wound to 11uh with 22awg with good success. if a smaller core is required, core outer diameters as small as 15.2mm (t60-2) wo rk well, but core temperature effects should be tested. the t60-2 core did not saturate dur ing short circuit testing, but maximum core temperatures must be considered and multip le layer winding must be used to achieve 11uh. multiple winding can increase winding capacitance, which may cause ringing and increased radiated emissions. bank winding tec hniques can minimize this effect. it should be noted that at core temperatures above 130c the single build wire used by most inductor manufacturers should be replaced with a heavy build wire. micrometals does not provide winding services, but many companies purchase directly from them and provide completely finished inductors. pulse engineering has a ssigned a part number for the t68-2 wound with 44 turns of 22 awg single build wire. the part number is pa0291. - amidon inc./american cores type-06 (carbonyl-e) toroidal iron powder cores. tripath has used t690-06 (17.5mm outer diameter) cores wound to 11uh with good success. amidon carries type-06 cores in the 23.9mm to 15.2 mm outer diameter range. they have assigned a part number for the t690-06 wound with 44 turns of 22 awg single build wire. this part is approved by tripath and is 690064422. power supplies the TA2022 requires the split supply rails vpp1( vpp2) and vnn1(vnn2), and v5. it also uses some additional voltages, vn10, vboot1 and vboot2 t hat are generated internally. the selection of components for the switching regulator is shown in the application / test diagram. minimum and maximum supply voltage operating range the TA2022 can operate over a wide range of power suppl y voltages from +/-12v to +/-36v. in order to optimize operation for either the low or high r ange, the user must select the proper values for r vnnsense , r vppsense , r fba , r fbb , and r fbc . please refer to the modulator feedback design and over/under-voltage protection sections for more additional information. vn10 supply the TA2022 has an internal hysteretic buck converte r, which, in conjunction with a few passive components, generates the necessary floating power supply for the mosfet driver stage (nominally 11v with the external components shown in applic ation / test circuit). the performance curves shown in the data sheet as well as efficiency measurements were done using the internal vn10 generator. tripath recommends that t he internal vn10 generator be used. in some cases, though, a designer may wish to use an external vn10 generator. the specification for vn10 quiescent current (65ma typical, 80ma maxi mum) in the electrical characteristics section states the amount of current needed when an external floating supply is used. if the internal vn10
tripath technology, inc. - technical information 23 TA2022 ? kli/1.0/11-01 generator is not used, tripath recommends s horting vn10sw(pin 5) to vn10gnd(pin 3) and vn10fdbk(pin 14) to vn10gnd(pin 3). vn10gnd should still be connected to the system power (high current) ground star for noise reasons. the external vn10 supply must be able to source a maximum of 80ma into the vn10 pin. thus, a positive supply must be used. in addition, this s upply must be referenced to the vnn rail. if the external vn10 supply does not track fluctuations in the vnn supply or is not able to source current into the vn10 pin, the TA2022 will, at the very least, not work, but more likely, be permanently damaged. figure 7 shows a simple circuit for an external vn10 supply. though simple, there is one problem with this circuit; the maximum input voltage of t he 7810. if the maximum input voltage of the 7810 is exceeded (typically this voltage is 35v), then the 7810 will be damaged which will likely cause damage to the TA2022. thus, this circuit should only be used where the vnn power supply is well regulated even under heavy load conditions (inc luding the effects of power supply pumping). figure 7: simple external vn10 supply figure 8 shows a much more robust vn10 supply. in this case, the maximum supply differential the lm317 experiences is the input voltage minus t he output voltage. the maximum differential specification is 40v for the lm317. when used as the vn10 supply for the TA2022, the maximum differential the lm317 will experience is 25v, ev en at maximum operating voltage of 36v for the TA2022. as configured, vout will be about 10.63v above vnn. figure 8: robust external vn10 supply it should be noted that the maximum power dissi pation for either figure 6 or figure 7 is: 1.6w 80ma(max.) 11v) (31v iout vout) (vin p dmax = ? ? = thus, the lm7810 or lm317 must be sufficiently heat sinked to sustain 80ma in the system ambient temperature. in the case where multiple ta 2022?s are run off the same vn10 generator, the power dissipation may be prohibitively large for the linear r egulator in conjunction with allowable heat sink. in these cases, a more sophisticated scheme using an additional transformer secondary winding referenced to vnn may be necessary to minimi ze the linear regulator power dissipation. vin to vn10 (pin 2) vout 0.1uf 0.1uf 10uf 7810 "gnd" to power supply "star" gnd 10uf to vnn (pin 8,9) adj 0.1uf vin 240 vout 10uf 1.8k 10uf to power supply "star" gnd to vnn (pin 8,9) 0.1uf to vn10 (pin 2) 10uf lm317
tripath technology, inc. - technical information 24 TA2022 ? kli/1.0/11-01 protection circuits the TA2022 is guarded against over-current, over / under-voltage and over-temperature conditions. if the device goes into an over-current or over / under-voltage condition, the hmute goes to a logic high indicating a fault condition. when this occu rs, the amplifier is muted, all outputs are tri- stated, and will float to approximately 2.5vdc. over-current protection an over-current fault occurs if more than approxim ately 8 amps of current flows from any of the amplifier output pins. this can occur if the speak er wires are shorted toget her or if one side of the speaker is shorted to ground. an over-current faul t sets an internal latch that can only be cleared if the mute pin is toggled or if the part is powered dow n. see the over-current curves in the typical characteristics section for more information. over/under voltage protection the TA2022 has built-in over and under voltage prot ection for both the vpp and vnn supply rails. the nominal operating voltage will typically be chosen as the supply ?center point.? this allows the supply voltage to fluctuate, both above and below, the nominal supply voltage. vppsense (pin 19) performs the over and undervolt age sensing for the positive supply, vpp. vnnsense (pin 18) performs the same function for the negative rail, v nn. in the simplest implementation, the supply is done via a single, exte rnal resistor per sense pin. this scheme is referred to as the ?single resistor? sense circuit. figure 9 shows the single resistor sense circuit. figure 9: single resistor sense circuit when the current through r vppsense (or r vnnsense ) goes below or above the values shown in the electrical characteristics section (caused by changing the power supply voltage), the TA2022 will be muted. vppsense is internally biased at 2.5v and vnnsense is biased at 1.25v. for the ?single resistor? sense case (as shown in the application / test diagram), these bias points must be taken into consideration when calculating the r vppsense or r vnnsense resistor. once the supply comes back into the supply volt age operating range (as defined by the supply sense resistors), the TA2022 will automatic ally be unmuted and will begin to amplify. there is a hysteresis range on both the vppsense and vnnsense pins. if the amplifier is powered up in the hysteresis band the TA2022 will be muted. thus, the usable s upply range is the difference between the over- voltage turn-off and under-voltage turn-off for both the vpp and vnn supplies. it should be noted that there is a timer of approximately 200ms with res pect to the over and under voltage sensing circuit. vpp 19 TA2022 18 vnn rvppsense vnnsense vppsense rvnnsense
tripath technology, inc. - technical information 25 TA2022 ? kli/1.0/11-01 thus, the supply voltage must be outside of the us er defined supply range for greater than 200ms for the TA2022 to be muted. the equation for calculating r vppsense is as follows: vppsense vppsense i 2.5v - vpp r = the equation for calculating r vnnsense is as follows: vnnsense vnnsense i vnn - 1.25v r = where i vppsense or i vnnsense can be any of the currents shown in the electrical characteristics table for vppsense and vnnsense, respectively. example: nominal supply voltage ? +/-32.5v +/-10% from this information, a value of r vppsense and r vnnsense can be calculated using the above formulas. 36v use 35.75v 1.1 32.5v vpp max = = 36v - use 35.75v 1.1 32.5v vnn max ? = ? = % 1 , k 243 use 242.75 a 138 2.5v - 36v r vppsense ? = = k ? where i vppsense is the minimum over-voltage turn off current for vppsense. % 1 , k 249 use 245.1 a 152 36v - - 1.25v r vnnsense ? = = k ? where i vnnsense is the minimum over-voltage turn off current for vnnsense. using the resistor values from above, the act ual minimum over voltage turn off points will be: 36.03v 2.5v 138 k ? 243 vpp n_off min_ov_tur = + = a 36.60v - a 152 k ? 49 2 1.25v vnn n_off min_ov_tur = ? = the other three trip points can be calculated usi ng the same formula but inserting the appropriate i vppsense (or i vnnsense ) current value. as stated earlier, the usable supply range is the difference between the minimum overvoltage turn off and maximum under voltage turn-off for both the vpp and vnn supplies. n_off max_uv_tur n_off min_ov_tur range vpp - vpp vpp = n_off max_uv_tur n_off min_ov_tur range vnn - vnn vnn = using the resistor values from above, and the maximum under voltage trip currents shown in the electrical characteristics table, the ma ximum under voltage turn off points will be: 23.64v 2.5v 87 k ? 243 vpp n_off max_uv_tur = + = a 22.41v - a 95 k ? 49 2 1.25v vnn n_off max_uv_tur = ? =
tripath technology, inc. - technical information 26 TA2022 ? kli/1.0/11-01 and the resultant supply ranges will be: 12.39v 23.64v 03 . 36 vpp range = ? = 14.19v - 22.41v 60 . 36 vnn range = ? ? ? = it should also be noted that the tolerance of the r vppsense (or r vnnsense ) resistors will effect the trip voltages and thus, the usable supply range. to mi nimize the additional variance tripath recommends 1% tolerance resistors. as a matter of completeness, the formulas below in clude the effect of resistor tolerance assuming a known value of r vppsense or r vnnsense . 2.5v ) 100 / tol 1 ( ) i r ( vpp trip vppsense n_off min_ov_tur + + = 2.5v ) 100 / tol 1 ( ) i r ( vpp trip vppsense n_off max_uv_tur + + = ) 100 / tol 1 ( ) i r ( 25 . 1 vnn trip vnnsense n_off min_ov_tur + ? = ) 100 / tol 1 ( ) i r ( 25 . 1 vnn trip vnnsense n_off max_uv_tur + ? = using a value of 243k ? for r vppsense and a value of 249k ? for r vnnsense , assuming 5% tolerance, along with the appropriate value of i trip , the trip voltages and supply ranges can be calculated. 34.44v 2.5v ) 100 / 5 1 ( ) 138 243k ? ( vpp n_off min_ov_tur = + + = a 24.70v 2.5v ) 100 / 5 1 ( ) a 87 243k ? ( vpp n_off max_uv_tur = + + = 9.74v 24.70v 44 . 34 vpp range = ? = 34.80v ) 100 / 5 1 ( ) a 152 k ? 49 2 ( 25 . 1 vnn n_off min_ov_tur ? = + ? = 23.59v ) 100 / 5 1 ( ) a 95 k ? 49 2 ( 25 . 1 vnn n_off max_uv_tur ? = + ? = 11.21v - 23.59v 80 . 34 vnn range = ? ? ? = thus, by using 5% resistors, the supply range for the vpp has been reduced by 2.65v while the vnn range has been reduced by approximately 3.0v (as compared to resistors with no tolerance variation). in actuality, if a 5% resistor was to be used, then the initial value of r vppsense and r vnnsense would have had to be adjusted such that the minimum over voltage turn off points would have never been less than +/-36v as defined by the supply voltage and tolerance specification. it should be noted that the values for v vppsense and v vnnsense shown in the electrical characteristics table were calculated using a value of 249k ? for both r vppsense and r vnnsense . in addition, for the maximum and minimum values, as opposed to the typi cal ones, a 1% tolerance resistor value around 249k ? was chosen to show the effect on supply r ange. thus, the minimum and maximum values would be ?worst case? assuming a supply voltage of 5v for the input section of the TA2022. the entire discussion thus far has been for the ?one resistor? sense circuit. this configuration requires a single resistor from either vppsense or vnnsense to the respec tive power supply. while the simplest configuration, in terms of ex ternal components, there are some drawbacks to this configuration. the first drawback is that the range for vpp range and vnn range are asymmetric due to the different internal bias voltages of vppsen se and vnnsense. a second issue is that current through r vppsense or r vnnsense will change if the v5 voltage is not exactly 5v, since the bias voltages of pin 18 and pin 19 are set by resistor dividers between v5 and agnd. with an additional resistor per supply sense pi n (2 resistors per vppsense or vnnsense), the drawbacks of the ?one resistor? sense circuit can be e liminated. in addition, the calculations of the sense resistors are actually more straightforward fo r the ?two resistor? sense circuit as opposed to the ?one resistor? scheme. figure 10 shows the proper c onnection for the ?two resistor? sense circuit for both the vppsense and vnnsense pins.
tripath technology, inc. - technical information 27 TA2022 ? kli/1.0/11-01 figure 10: two resistor sense circuit the equation for calculating r vpp1 is as follows: vppsense vpp1 i vpp r = set vpp1 vpp2 r r = . the equation for calculating r vnnsense is as follows: vnnsense vnn1 i vnn r = set vnn1 vnn2 r 3 r = . i vppsense or i vnnsense can be any of the currents shown in the electrical characteristics table for vppsense and vnnsense, respectively. example: nominal supply voltage ? +/-32.5v +/-10% from this information, a value of r vpp1 , r vpp2 , r vnn1 , and r vnn2 can be calculated using the above formulas. 36v use 35.75v 1.1 32.5v vpp max = = 36v - use 35.75v 1.1 32.5v vnn max ? = ? = % 1 , k 261 use 260.87 a 138 36v r vpp1 ? = = k ? set % 1 , 261 r vpp2 ? = k . where i vppsense is the minimum over-voltage turn off current for vppsense. % 1 , k 237 use 236.84 a 152 36v r vnn2 ? = = k ? set % 1 , k ? 715 r vnn2 = . where i vnnsense is the minimum over-voltage turn off current for vnnsense. rvnn2 TA2022 rvnn1 rvpp1 vpp 18 vnnsense vppsense rvnn2 v5 vnn v5 19
tripath technology, inc. - technical information 28 TA2022 ? kli/1.0/11-01 the two additional resistors, r vpp2 and r vnn2 compensate for the internal bias points. thus, r vpp1 and r vnn1 can be used for the direct calculation of the actual vpp and vnn trip voltages without considering the effect of r vpp2 and r vnn2 . using the resistor values from above, the act ual minimum over voltage turn off points will be: 36.02v 138 k ? 261 vpp n_off min_ov_tur = = a 36.24v - a 152 k ? 37 2 vnn n_off min_ov_tur = ? = the other three trip points can be calculated usi ng the same formula but inserting the appropriate i vppsense (or i vnnsense ) current value. as stated earlier, the usable supply range is the difference between the minimum overvoltage turn off and maximum under voltage turn-off for both the vpp and vnn supplies. n_off max_uv_tur n_off min_ov_tur range vpp - vpp vpp = n_off max_uv_tur n_off min_ov_tur range vnn - vnn vnn = using the resistor values from above, and the maximum under voltage trip currents shown in the electrical characteristics table, the ma ximum under voltage turn off points will be: 22.71v 87 k ? 261 vpp n_off max_uv_tur = = a 22..51v - a 95 k ? 37 2 vnn n_off max_uv_tur = ? = and the resultant minimum supply ranges will be: 13.31v 22.71v 02 . 36 vpp range = ? = 13.73v - 22.51v 24 . 36 vnn range = ? ? ? = by adding a total of 2 additional resistors (1 for vppsense and 1 for vnnsense), the minimum supply range is now about 3% different as opposed to 13% for the ?single resistor? sense case. in addition, the vpp range has been increased by nearly one volt. this represents a 7% improvement in supply range for vpp. as in the single resistor case, the tolerance of the r vpp1 and r vpp2 (or r vnn1 and r vnn2 ) resistors will affect the trip voltages and thus, the usable supply range. as the nominal supply voltage is decreased, the effect of r vpp2 and r vnn2 becomes more pronounced. to minimize the additional variance tripath recommends 1% toleranc e resistors. it is possible to calculate the effect of resistor tolerances for the ?two resistor? sense circuit, but ultimately, 1% resistors should be used for the sense circuit in all, but the tightest regulated supply schemes. over temperature protection an over-temperature fault occurs if the juncti on temperature of the part exceeds approximately 165 c. the thermal hysteresis of the part is approximately 30 c, therefore the fault will automatically clear when the junction temperature drops below 135 c. hmute (pin 32) the hmute pin is a 5v logic output that indicates various fault conditions within the device. these conditions include: over-current, overvoltage and undervoltage. the hmute output is capable of directly driving an led through a series 2k ? resistor. heat sink requirements most applications it will be necessary to fasten t he TA2022 to a heat sink. the determining factor is that the 150 c maximum junction temperature, t j (max) cannot be exceeded, as specified by the following equation:
tripath technology, inc. - technical information 29 TA2022 ? kli/1.0/11-01 p diss = ( ) ? where: p diss = maximum power dissipation t jmax = maximum junction temperature of TA2022 t a = operating ambient temperature ja = junction-to-ambient thermal resistance ja = jc + cs + sa example: what size heat sink is required to operate t he TA2022 at 80w per channel continuously in a 70oc ambient temperature? p diss is determined by: efficiency = = in out p p = diss out out p p p ? p diss (per channel) = w 88 . 5 1 90 85 . 0 90 = ? = ? out out p p thus, p diss for two channels = 31.76w ja = ( ) ? = 76 . 31 70 150 ? c/w the jc of the TA2022 is 1.0 c/w, so a heat sink of 1.32 c/w is required for this example (assuming a cs = 0.2 c/w). in actual applications, ot her factors such as the average p diss with a music source (as opposed to a continuous sine wave) and regulatory agency testing requirements will help determine the size of the heat sink required. performance measurements of the TA2022 the TA2022 operates by generating a high frequenc y switching signal based on the audio input. this signal is sent through a low-pass filter (external to the tripath amplifier) that recovers an amplified version of the audio input . the frequency of the switching patte rn is spread spectrum in nature and typically varies between 100khz and 1mhz, which is well above the 20hz ? 20khz audio band. the pattern itself does not alter or distort the audi o input signal, but it does introduce some inaudible components. the measurements of certain perform ance parameters, particularly noise related specifications such as thd+n, are significantly affected by the design of the low-pass filter used on the output as well as the bandwidth setting of the measurement instrument us ed. unless the filter has a very sharp roll-off just beyond the audio band or the bandwidth of the meas urement instrument is limited, some of the inaudible noise components introduced by the TA2022 amplifier switching pattern will degrade the measurement. one feature of the TA2022 is that it does not require large multi-pol e filters to achieve excellent performance in listening tests, usually a more cr itical factor than performance measurements. though using a multi-pole filter may remove high-frequency noise and improve thd+n type measurements (when they are made with wide-bandwid th measuring equipment), these same filters degrade frequency response. the TA2022 evaluation board uses the application/test circuit of this data sheet, which has a simple two-pole output filt er and excellent performance in listening tests. measurements in this data sheet were taken using th is same circuit with a limited bandwidth setting in the measurement instrument.
tripath technology, inc. - technical information 30 TA2022 ? kli/1.0/11-01 package information 48-pin dip
tripath technology, inc. - technical information 31 TA2022 ? kli/1.0/11-01 advanced information this is a product in development. tripath technology, in c. reserves the right to make any changes without further notice to improve re liability, function and design. tripath and digital power processing are trademar ks of tripath technology, inc. other trademarks referenced in this document are owned by their respective companies. tripath technology, inc. reserves the right to make changes without further notice to any products herein to improve reliability, function or design. tripath does not assume any liabilit y arising out of the application of use of any product or circuit described herein; neither does it convey any licens e under its patent rights nor the rights of others. tripath?s product are not authorized fo r use as critical components in life support devices or systems without the express written consent of the president of tripath techonol ogy, inc. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in this labeling, can be reasonably expected to result in significant injury of the user. 2. a critical component is any co mponent of a life support device or system whose failure to perform can be reasonably expected to cause t he failure of the life support device or system, or to affect its safety or effectiveness. other useful documents concerning the TA2022 available on the tripath website. ? eb-TA2022 evaluation board ? ta 2022 evaluation board document ? rb-TA2022 six channel board ? six channel reference design using the TA2022. contact information tripath technology, inc 2560 orchard parkway, san jose, ca 95131 408.750.3000 - p 408.750.3001 - f for more sales information, please visit us @ www.tripath.com/cont_s.htm for more technical information, please visit us @ www.tripath.com/data.htm

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