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tripath technology, inc. - technical information 1 TK2019 ? mc/2.1/10-03 TK2019 stereo 20w (4 ? ) class-t? digital audio amplifier driver using digital power processing (dpp?) technology preliminary information revision 2.1 ? october 2003 general description the TK2019 (tc2001/tps1035 chipset) is a stereo single ended 20w continuous average power per channel, class-t digital audio power amplifier using tripath?s proprietary digital power processing tm technology. the TK2019 chipset consists of 1 tc2001 and 2 tps1035?s to obtain a single ended stereo configuration. cla ss-t amplifiers offer both the audio fidelity of class-ab and the power efficiency of class-d amplifiers. applications 5.1-channel powered dvd player mini/micro component systems home theater stereo applications (4 ? / 8 ? ) benefits single supply operation very high efficiency wide dynamic range compact layout features class-t architecture high output power 20w @ 4 ?, 10% thd+n single ended 11w @ 8 ? , 10% thd+n single ended audiophile quality sound 0.03% thd+n @ 11w 4 ? single ended 0.03% thd+n @ 6w 8 ? single ended high efficiency 92% @ 20w 4 ? single ended 93% @ 11w 8 ? single ended dynamic range >100 db
tripath technology, inc. - technical information 2 TK2019 ? mc/2.1/10-03 absolute maximum ratings ? tc2001 (note 1) symbol parameter value units v 5 5v power supply 6 v vlogic input logic level v 5 +0.3v v ta operating free-air temperature range -40 to 85 c t store storage temperature range -55 to 150 c t jmax maximum junction temperature 150 c esd hb esd susceptibility ? human body model (note 2), all pins 2000 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: human body model, 100pf discharged through a 1.5k ? resistor. absolute maximum ratings ? tps1035 (note 1) symbol parameter value units v cc power supply 26 v vlogic input logic level 5.5 v t a operating free-air temperature range -40 to 85 c t store storage temperature range -40 to 150 c t jmax maximum junction temperature 150 c esd hb esd susceptibility ? human body model (note 2), all pins except 1, 8 pins 1, 8 2000 400 v esd mm esd susceptibility ? machine model (note 3), all pins 200 v note 3: machine model, 220pf ? 240pf discharged through all pins. operating conditions ? tc2001 symbol parameter min. typ. max. units v5 supply voltage 4.5 5 5.5 v v hi logic input high v5-1.0 v v lo logic input low 1 v t a operating temperature range -40 25 85 c operating conditions ? tps1035 symbol parameter min. typ. max. units v cc power supply 8 25 v v hi logic input high tbd v v lo logic input low tbd v t a operating temperature range -40 25 85 c thermal characteristics tc2001 symbol parameter value units ja junction-to-ambient thermal resistance (still air) 80 c/w
tripath technology, inc. - technical information 3 TK2019 ? mc/2.1/10-03 tps1035 symbol parameter value units ja junction-to-ambient thermal resistance 50 c/w jc junction-to-case thermal resistance 8 c/w electrical characteristics ? tc2001 symbol parameter min. typ. max. units i5 supply current 60 ma fsw switching frequency (adjustable via cfb) 600 650 khz v in input sensitivity 0 1.5 v v outhi high output voltage v5-0.5 v v outlo low output voltage 100 mv r in input impedance 2 k ? input dc bias 2.5 v electrical characteristics ? TK2019 t a = 25 c. see application/test circuit. unle ss otherwise noted, the supply voltage is v dd = 24v. symbol parameter conditions min. typ. max. units i q quiescent current (no load, mute = 0v) v dd = 24v v5 = 5v 20 27 60 ma ma i mute mute supply current (no load, tc2001 mute = 5v, tps1035 sleep = 5v) v dd = 24v v5 = 5v 2 7 a 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 i sc short circuit current limit v dd = 24v, t=25 o c 7.5 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 = 187k ? (note 4, note 5) over-voltage turn on (muted) over-voltage turn off (mute off) under-voltage turn off (mute off) under-voltage turn on (muted) 25.8 11.6 30.3 28.8 14.8 13.5 33.3 16.3 v v v v note 4: these supply voltages are calculated using the ivppsense values shown in the electrical characteristics table. the typical voltage values shown are calc ulated using a rvppsense val ue of 187kohm without any tolerance variation. the minimum and maximum voltage limits shown include either a +1% or ?1% (+1% for over-voltage turn on and under-voltage turn off, -1% fo r over-voltage turn off and under-voltage turn on) variation of rvppsense off the nominal value. these voltage specifications are examples to show both typical and worst case voltage ranges for a given rvppsen se resistor values of 187kohm. please refer to the application information section for a more detail ed description of how to ca lculate the over and under voltage trip voltages for a given resistor value. note 5: the fact that the over-vol tage turn on specifications exceed the absolute maxi mum of 26v for the TK2019 does not imply that the part will work at these elevated supply voltages. it also does not imply that the TK2019 is tested or guaranteed at these supply voltages. the supply vo ltages are simply a calculation based on the process spread of the i vppsense currents (see note 7). the supply voltage must be maintained below the absolute maximum of 26v or permanent damage to the TK2019 may occur.
tripath technology, inc. - technical information 4 TK2019 ? mc/2.1/10-03 performance characteristics ? TK2019 t a = 25 c. unless otherwise noted, v dd = 24v, f=1khz, and the meas urement bandwidth is 20khz. symbol parameter conditions min. typ. max. units p out output power (continuous average/channel) (note 13) v dd = 24v, r l = 8 ? thd+n = 0.03% thd+n = 1.0% thd+n = 10.0% v dd = 24v, r l = 4 ? thd+n = 0.03% thd+n = 1.0% thd+n = 10.0% 6 8 11 11 15 20 w w w w w w thd + n total harmonic distortion plus noise p out = 5w/channel, r l = 8 ? v cc = 24v p out = 10w/channel, r l = 4 ? v cc = 24v 0.025 0.025 % % ihf-im ihf intermodulation distortion 19khz, 20khz, 1:1 (ihf), r l = 4 ? p out = 2.5w/channel 0.01 % snr signal-to-noise ratio a-weighted 0db = 10w/channel, r l = 8 ? 102 db cs channel separation 0db = 6.5w, r l = 4 ? , f=1khz 72 db a v amplifier gain p out = 5w/channel, r l = 8 ? , see application / test circuit 10 v/v a verror channel to channel gain error p out = 5w/channel, r l = 8 ? see application / test circuit 0.5 db power efficiency p out = 11w/channel, r l = 8 ? p out = 20w/channel, r l = 4 ? 93 92 % % e n output noise voltage a-weighted, input ac grounded, r fbc = 9.1k ? , r fbb = 1k ? 75 v
tripath technology, inc. - technical information 5 TK2019 ? mc/2.1/10-03 tc2001 audio signal processor pin descriptions pin function description 1 biascap bandgap reference times two (typically 2.5vdc). used to set the common mode voltage for the input op am ps. this pin is not capable of driving external circuitry . 2, 6 fbkgnd2, fbkgnd1 ground kelvin feedback (channels 1 & 2) 3 dcmp internal mode selection. this pin must be grounded for proper device operation. 4, 7 fbkout2, fbkout1 switching feedback (channels 1 & 2) 5 vpwr test pin. must be left floating. 8 hmute logic output. a logic high indicates both amplifiers are muted, due to the mute pin state, or a ?fault?. 9, 12 y1, y2 non-inverted sw itching modulator outputs. 10, 11 y1b, y2b inverted sw itching modulator outputs. 13 nc no connect 14, 16 ocd2, ocd1 over current detect pi ns. these pins should be tied to ground. 15 ref internal bandgap reference vo ltage; approximat ely 1.2 vdc. 17 vnnsense negative supply voltage sense inpu t. this pin is used for both over and under voltage sensing for the vnn supply. not used on the TK2019. connect this pin to agnd through a 10k ? resistor. 18 ovrldb a logic low output indicates the input signal has over loaded the amplifier. 19 vppsense positive supply voltage sense input. this pin is used for both over and under voltage sensing for the vpp supply. 20 agnd analog ground. 21 v5 5 volt power supply input. 22, 27 oaout1, oaout2 input stage output pins. 23, 28 inv1, inv2 single-ended inputs. inputs are a ?virtual? ground of an inverting opamp with approximately 2.4vdc bias. 24 mute when set to logic high, both am plifiers are muted and in idle mode. when low (grounded), both amplifiers ar e fully operational. if left floating, the device stays in the mute mode. ground if not used. 25, 26 bbm1, bbm0 break-before-make timing c ontrol to prevent shoot -through in the output mosfets. when using with the tps1035, these pins should both be set to 5v. tc2001 audio signal processor pinout ref vnnsense vppsense agnd oaout1 mute bbm1 bbm0 oaout2 inv2 fbkgnd2 ocd2 y2 y2b y1b y1 hmute fbkout1 fbkgnd1 vpw r fbkout2 dcmp 1 15 14 13 11 10 12 9 8 7 6 5 4 3 2 28-pin soic (top view) 16 17 18 biascap inv1 v5 ovrldb ocd1 nc 21 20 19 22 23 24 25 26 27 28
tripath technology, inc. - technical information 6 TK2019 ? mc/2.1/10-03 tps1035 power stage pin descriptions pin function description 1 input input pin for power stage. 2 vdd positive supply pin. 3 output output pin. 4 pgnd power ground pin. 5 vboot bootstrapped voltage to supply driv e to gate of high-side output mosfet. 6 sleep sleep input pin. when set to logic level high, sleep mode is enabled. when set to logic level low (grounded), sleep mode is disabled. 7 bypass bypass pin for the gate drive power supply. the gate drive for the output mosfets are internally generated from vdd. this pin should be connected to ground through a 0.1uf capacitor. this pin mu st be connected to the fault pin (pin 8) through a 27k ? resistor. 8 fault fault output pin. during normal operat ion this pin is high. if an overcurrent or over temperature condition is detected t he fault pin will become low. this pin must be connected to the bypass pin (pin 7) through a 27k ? resistor. tps1035 power stage pinout (top view with heat slug down) vboot sleep bypass fault vdd pgnd output 1 4 3 2 8-pin soic with heatslug (top view) input 5 6 7 8
tripath technology, inc. - technical information 7 TK2019 ? mc/2.1/10-03 application / test diagram hmute 8 analog ground pow er ground *r vpp1 vpp 19 v ppsense 17 vnnsense 187k ?, 1% 13 nc *r vpp2 v5 * the values of th es e components must be adjusted based on supply vo lta g e range. see application inform ation. 187k ?, 1% 25 bbm1 26 bbm0 3 dcomp 0 ? processing & modulation processing & modulation tc2001 vp1 inv 1 c i 2.2uf 22 23 + v5 agnd mute 24 5v v5 biascap c a 0.1uf 1 2.5v 200k ? offset trim circ uit - + r ofa 50k ? v5 (pin 27) agnd r ofb 1m ? c of 0.1uf r f 20k ? r i 20k ? vp2 in2 c i 2.2uf 27 28 + r f 20k ? r i 20k ? - + v5 agnd 15 ref r ref 8.25k ?, 1% r ofa 50k ? v5 (pin 27) r ofb 1m ? c of 0.1uf offset trim circ uit fbkout2 4 fbkgnd2 2 *r fbb 1.0k ? *r fb c 9.1k ? c fb 560pf agnd (pin 28) ocd2 14 fbkout1 7 fbkgnd1 6 *r fbb 1.0k ? *r fb c 9.1k ? c fb 390pf agnd (pin 28) ocd1 16 c s 0.1uf 21 20 v5 agnd 5v y1 y1b y2 y2b 9 10 12 11 v5 (pin 27) inp ut logic/ level shift internal regulator 8 6 7 1 5 2 3 4 tps1035 vdd pgnd v boot output bypass fa ult sleep input l o 10uh c o 0.22uf d s murs105t3 d s murs105t3 c b oot 0.22uf d b oot 1 murs105t3 c hbr 0.1uf c b 0.1uf inp ut logic/ level shift internal regulator 8 6 7 1 5 2 3 4 tps1035 vdd pgnd v boot output bypass fa ult sleep input l o 10uh c o 0.22uf d s murs105t3 d s murs105t3 c b oot 0.22uf d b oot 1 murs105t3 c hbr 0.1uf c b 0.1uf c z 0.22uf r z 20 ?, 2w r l 4 ? or 8 ? r l 4 ? or 8 ? c z 0.22uf r z 20 ?, 2w + + c out 1000uf c out 1000uf + 24v 24v 24v *r fb c 9.1k ? *r fbb 1.0k ? r bias1 4.64k ? r bias2 54.9k ? c bypass 0.1uf c bypass 10.0uf r hmut e 4.99k ? r p 10k ? 5v d ch mbr0520l r base 1k ? r c 100k ? 5v q 2 2n3906 d p 1n914 24v hmute r off 100k ? d b oot 5.1v zener diode d c 1n914 r d 100k ? d c 1n914 r d 100k ? 24v 24v r out 1 8.45k ? r out 2 20k ? 24v r out 1 8.45k ? r out 2 20k ? 24v d b oot 2 6.2v zener diode d b oot 2 6.2v zener diode q 1 2n3906 d ch mbr0520l r b 27k ? r b 27k ? 10k ? r vnn *r fb c 9.1k ? *r fbb 1.0k ?
tripath technology, inc. - technical information 8 TK2019 ? mc/2.1/10-03 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 fbb feedback divider resistor connected to agnd. the value of this resistor depends on the supply voltage setting and helps set the TK2019 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 the out1a/out2a to fbkout1/fbkout2 or out1b/out2b to fbkgnd1/fbkgnd2. the value of this resistor depends on the supply voltage setting and helps set the TK2019 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 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 ofb potentiometer used to manually trim t he dc offset on the output of the TK2019. r ofa resistor that limits the manual dc offset trim range and allows for more precise adjustment. r ref bias resistor. locate close to pin 15 and ground at pin 20. c s supply decoupling for the power supply pi ns. for optimum performance, these components should be located close to the tc2001/tps1035 and returned to their respective ground as shown in the application/test circuit. 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 1 watt. 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 = . 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 su staining the ripple current caused by the switching outputs. electrolytic capacitors should not be used. c hbr high-frequency bypass capacitor for v dd ? gnd on each supply pin. a 35v rating is required for this component. c boot boot strap capacitor that enables the charge pump for the high side gate drive for the internal h-bridge. d boot bootstrap diode. this diode charges up the bootstrap capacitor when the output is at ground to drive the high side gate circuitry. a fast or ultra fast recovery diode is recommended for the bootstrap circuitry. in addition, the bootstrap diode must be able to sustain the entire vdd voltage. thus a 50v (or greater) diode should be used. c dm differential mode capacitor that reduces residual switching noise.
tripath technology, inc. - technical information 9 TK2019 ? mc/2.1/10-03 c b bypass capacitor for the internal regulator that powers the gate drive circuitry. d s mosfet protection diode. this diode absorbs any high frequency overshoots or undershoots caused by the output inductor l o during high output current conditions. in order for this diode to be effective it mu st be connected directly to the drain of the topside mosfet (pin 2) and the output (pin 3) and source of bottom side mosfet (pin 4) and the output (pin 3). an ultra fa st recovery diode that can sustain the entire vcc voltage should be used here. thus a 50v or greater diode must be used. r vpp1 overvoltage and undervoltage sense resistor for the positive supply (vdd). please refer to the electrical characteristics se ction 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 vpp2 secondary overvoltage and undervoltage sens e resistor for the positive supply (vdd). this resistor accounts for the internal v ppsense bias of 2.5v. nominal resistor value should be equal to that of r vpp1 . please refer to the over / under- voltage protection section in the applicati on information for a detailed discussion of the internal circuit operation and external component selection. r vnn not used on TK2019. connect this pin to agnd through a 10k ? resistor. c a biascap decoupling capacitor. should be located close to pin 1 of the tc2001 and grounded at pin 20 of the tc2001. r hmute base resistor to limit the current output from the hmute pin. d ch diode to keep the bypass pin (pin 7) of the tps1035 charged to 5v while hmute is high. this diode should be a schottky diode. q 1 pnp transistor to keep the bypass pin (pin 7) of the tps1035 charged to 5v whenever the hmute is high. q 2 pnp transistor to keep hmute high and mute the amplifier if the 5v supply is turned off before the 24v supply. if the am plifier is not muted and the 5v supply is turned off before the 24v supply, the am plifier will have an audible pop. r base base resistor for limiting the current entering the base for q2. r c pull down resistor to pull the collector of q2 to ground if both the 5v supply and the 24v supply is on and q2 is off. r off resistor that limits the current from t he 24v supply going into the 5.1v zener diode (d z ). d p diode in series with the collector of q2 to pull hmute high if the 5v supply is turned off before the 24v supply. d z 5.1v zener diode to keep the emitter of q2 to 5.1v so that when q2 is on the hmute pin will not exceed 5v. r bias1 bias resistor to bias the fbkgnd pins (pins 2 and 8 on tc2001) to 2.5v. typically used value is 4.64k ? . r bias2 second bias resistor to bias the fbkgnd pins (pins 2 and 8 on tc2001) to 2.5v. the value of r bias2 when placed in parallel with r fbb and r fbc should have equivalent resistance to r bias1 . please see the modulator feedback design paragraphs in the application information section. an equivalent equation would be r bias1 = 1/ (r fbb + r fbc ) + 1/ r bias2 . r d resistor to limit the current flowing into diode d c . d c diode to connect the vboot pin (pin 5 of the tps1035) to the 24v supply so that the vboot pin is charged up while the t ps1035 is muted. this helps prevent clicks and pops while the sleep is disabled on the tps1035. d boot2 protection diode for the vboot pin (pin 5 of the tps1035) so that the vboot pin will never exceed 6.2v. r out1 bias resistor to keep the output capacitor c out charged to vdd/2. typically used value is 8.45k ? . r out2 bias resistor used in conjunction with r out1 to keep the output capacitor c out charged to vdd/2. typically used value is 20k ? . r b for proper operation of the tps1035, the f ault pin (pin 8) must be connected to the bypass pin (pin 7) through a 27kohm resistor. c out output capacitor in series with the output to block dc current to flow to the output load. this capacitor will form a high pa ss filter with output load with a cutoff frequency at ) c r 2 ( 1 f i i c = . where r is the resistive va lue of the output load.
tripath technology, inc. - technical information 10 TK2019 ? mc/2.1/10-03 typical performance characteristics thd+n vs output power 0.01 10 0.02 0.05 0.1 0.2 0.5 1 2 5 % 1 50 2 3 4 5 6 7 8 9 10 20 30 40 w f = 1khz vdd = 24v bw = 22hz - 22khz aes17 filter r l = 8 ? r l = 2 ? r l = 4 ? thd+n vs frequency 0.005 10 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 thd+n (%) 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) f = 1khz vdd = 24v pout = 5w /channel bw = 22hz - 22khz r l = 8 ? r l = 4 ? intermodulation distortion -120 +0 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 amplitude (dbr) 60 30k 100 200 500 1k 2k 5k 10k 20k frequency (hz) vdd = 24v pout = 2.5w/channel r l = 4 ? 19khz, 20khz 1:1 0db = 3.2vrms noise floor -120 +0 -108 -96 -84 -72 -60 -48 -36 -24 -12 amplitude (dbv) 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) vdd = 24v pout = 0w/channel r l = 4 ? a v = 10v/v bw = 22hz - 22khz channel seperation vs frequency -120 +0 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 amplitude (dbr) 20 20k 50 100 200 500 1k 2k 5k 10k frequency (hz) vdd = 24v pout = 6.5w/channel r l = 4 ? 0db = 5.1vrms bw = 22hz - 22khz efficiency vs output power 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 output power (w) efficiency (%) vdd = 24v thd+n <10% 4 ohms 8 ohms
tripath technology, inc. - technical information 11 TK2019 ? mc/2.1/10-03 application information TK2019 basic amplifier operation the tc2001 is a 5v cmos signal processor that amplifies the audio input signal and converts the audio signal to a switching pattern. this switching pattern is spread spectrum with a typical idle switching frequency of about 700khz. the swit ching 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 tps1035 is a mosfet output stage that level-shi fts the signal processor?s 5v switching patterns to the power supply voltages and drives the pow er mosfets. the power mosfets are n-channel devices configured in half-bridges and are used to supply power to the output load. the outputs of the power mosfets 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 output lc filter is used, but this si gnal is outside of the audio band and will not affect audio performance. circuit board layout the TK2019 is a power (high current) amplifier that operates at relatively high switching frequencies. the output of the amplifier sw itches between vdd and gnd 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 inductanor. to avoid subjecting the TK2019 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. the following components are important to plac e near their associated tc2001/tps1035 pins and are ranked in order of layout importance, ei ther for proper device operation or performance 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 vcc pins. please note that the four vdd pins must be decoupled separately. in addition, the voltage rating for c hbr should be 35v as this capac itor is exposed to the full supply range. - 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. - to minimize noise pickup and minimize thd+n, r fbc should be located as close to the tc2001 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. in general, to enable placement as close to the tc2001/tps1035, and minimize pcb parasitics, the capacitors listed above (with the ex ception of the bulk capacitors) should be surface mount types.
tripath technology, inc. - technical information 12 TK2019 ? mc/2.1/10-03 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 . - the modulator feedback resistors should all be grounded together through a direct connection to pin 20 on the tc2001. TK2019 grounding proper grounding techniques are required to ma ximize TK2019 functionality and performance. parametric parameters such as thd+n, noise floor and cross talk 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 TK2019 as well as general ?audio system? design rules. the TK2019 is divided into two sections: the input se ction, and the output (hi gh power) section. on the TK2019 evaluation board, the ground is also divi ded 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. 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 voltage for the power stage. depending on the maximum supply voltage, the feedback ratio will need to be adjusted to maximize performance. the values of rfbb and rfbc (see explanation below) defi ne the gain of the modulator. on ce these values are chosen, based on the maximum supply voltage, the gain 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. the modulator feedback resistors are: r fbb = user specified; typically 1k ? fbb fbb cc fbc r 4v r v r ? ? ? ? ? ? ? ? = modulator feedback bias resistors r bias1 and r bias2 set the bias of node 1 to vdd/2. the equivalent resistance of r bias2 , r fbc1 , r fbb1 , r fbc2 , and r fbb2 should be the same as r bias1 .
tripath technology, inc. - technical information 13 TK2019 ? mc/2.1/10-03 + 24v r fbc1 9.1k ? r bias1 4.64k ? r bias2 54.9k ? c bypass 0.1uf c bypass 10.0uf r fbc2 9.1k ? r fbb2 1.0k ? r fbb1 1.0k ? tc2001 6 2 node 1 figure 1: modulator feedback bias resistors the equivalent formula to calculate r bias1 is: bias2 fb bias1 r 1 r 1 r 1 + = where r fb is: fbb2 fbc2 fbb1 fbc1 fb r r 1 r r 1 r 1 + + + = TK2019 amplifier gain the gain of the TK2019 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 stage input v TK2019 v a * a a = ? ? ? ? ? ? + fbb fbb fbc i f TK2019 v r r r r r a for example, using a TK2019 with the following external components, r i = 20k ? r f = 20k ? r fbb = 1k ? r fbc = 9.1k ? v v 10 1k ? 1k 9.1k ? 20k ? 20k ? a TK2019 v ? ? ? ? ? ? ? + please note that output 1 and output 2, as shown in the application/test diagram, are out of phase with respect to the input signal. this phase re versal can be eliminated by connecting the negative terminals of the speakers to output 1 and output 2 and the positive speaker terminals to ground.
tripath technology, inc. - technical information 14 TK2019 ? mc/2.1/10-03 input stage design the tc2001 input stage is configured as an inverting am plifier, allowing the system designer flexibility in setting the input stage gain and frequency response. figure 2 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. tc2001 input2 oaout2 v5 oaout1 + - ci + - inv1 input1 biascap agnd rf ri ci rf agnd inv2 v5 ri figure 2: 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 amplifie rs are biased at approximat ely 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 stage input v 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)
tripath technology, inc. - technical information 15 TK2019 ? mc/2.1/10-03 mute control when a logic high signal is supplied to mute, bot h amplifier channels are muted (both high- and low- side transistors are turned off). when a logic level low is supplied to mute, both amplifiers are fully operational. there is a delay of approximately 200 milliseconds between the de-assertion of mute and the un-muting of the TK2019. 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 TK2019 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 tc2001 mute pin high when the v5 voltage is below 4.5v. this will ensure proper operation of the TK2019 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 TK2019 amplifier, the cause may be other circuitry external to the TK2019. while the tk 2019 has circuitry to suppress turn-on and turn-off transients, the combination of power supply and ot her audio circuitry with the TK2019 in a particular application may exhibit audible transients. one so lution that will completely eliminate turn-on and turn-off pops and clicks is to use a relay to connect/d isconnect that amplifier from the speakers with the appropriate timing during power on/off. output voltage offset the TK2019 does not have internal compensation for dc offset. the output offset voltage must be trimmed with a potentiometer at the inv1/inv2 pins of the tc2001. if the output offset voltage is not trimmed the output power of the TK2019 will be reduc ed. trimming the output offset voltage also reduces the turn on pop. the output offset voltage should be measured before the load on the positive terminal of the output capacitor cout. this voltage should be trimmed to vdd/2. output filter design tripath amplifiers generally have a higher swit ching frequency than pwm implementations, allowing the use of higher cutoff frequency filters and reducing the load dependent peaking/drooping in the 20khz audio band. this is especially important fo r applications 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 ) should be placed at the filter output to control the im pedance ?seen? by the tps1035 when not attached to a speaker load. the TK2019 works well with a 2 nd order, 80khz lc filter with l o = 10uh and c o = 0.22uf and r z = 20 ohm/1w and c z = 0.22uf. output inductor selection is a crit ical design step. the core materi al and geometry of the output filter inductor affects the TK2019 distortion levels, e fficiency, power dissipation and emi output. wound iron powder toroidal cores are the recomm ended inductor choice for the TK2019. toroidal cores have less flux leakage compared to shielded bobbin or shielded smd inductors, resulting in reduced emi and improved channel separation. for typical applications we recommend the micrometals type-2 iron powder (carbonyl-e) core. this core material has low permeability metal powder and a distributed air gap for increased energy storage capability. this allows for a small footprint with high peak current capability. minimum and maximum supply voltage operating range the TK2019 can operate over a wide range of power suppl y voltages from +7.5v to +25v. in order to optimize operation for either the low or high range, the user must select the proper values for r fbb , and r fbc as well as r vpp1 and r vpp2 .
tripath technology, inc. - technical information 16 TK2019 ? mc/2.1/10-03 over- and under-voltage protection the tc2001 senses the power rails through exte rnal resistor networks connected to vppsense. the over- and under-voltage limits are determined by the values of the resistors in the networks, as described in the table ?test/application circuit co mponent values?. if the supply voltage falls outside the upper and lower limits determined by the resist or networks, the tc2001 shuts off the tps1035 output stage. the removal of the over-voltage or under-voltage condition returns the TK2019 to normal operation. please note that tr ip points specified in the electric al characteristics table are at 25 c and may change over temperature. the tc2001 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. for the TK2019 only the vpp (vdd) supply rail will be sensed and the v nn sensing will not be used so pin 17 of the tc2001 will be shorted to ground. vppsense (pin 19) performs the over and undervoltage sensing for the positive supply, vpp. when the current through r vppsense goes below or above the values shown in the electrical characteristics section (caused by changing the power supply vo ltage), the TK2019 will be muted. vppsense (pin 19) is internally biased at 2.5v. once the supply comes back into the supply volt age operating range (as defined by the supply sense resistors), the TK2019 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 TK2019 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 t he vpp supply. it should be noted that there is a timer of approximately 200ms with respect to the over and under voltage sensing circuit. thus, the supply voltage must be outside of the user def ined supply range for greater than 200ms for the TK2019 to be muted. the equation for calculating r vpp1 is as follows: vppsense vpp1 i vpp r = set vpp1 vpp2 r r = . i vppsense can be any of the currents shown in t he electrical characteristics table for vppsense. the two 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 act ual 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: rn_off) (min_ov_tu vppsense vpp1 n_off min_ov_tur i r vpp = the other three trip points can be calculated usi ng the same formula but inserting the appropriate i vppsense current value. as stated earlier, the us able supply range is the difference between the minimum overvoltage turn off and maximum under voltage turn-off for the vpp supply. n_off max_uv_tur n_off min_ov_tur range vpp - vpp vpp =
tripath technology, inc. - technical information 17 TK2019 ? mc/2.1/10-03 protection circuits the TK2019 is protected against over-current, over / under-voltage and over-temperature conditions. 8 tps1035 fault 1k ? fdll914 8 tps1035 fault 1k ? fdll914 10k ? 20k ? 510k ? 5v 5v mute pin (pin 24 of tc2001) q2 2n3906 + hmute pin (pin 8 of tc2001) 3k ? 30k ? 22uf q1 2n3906 3 3 sleep sleep hmute pin (pin 8 of tc2001) figure 3 figure 3 shows an overcurrent detection circuit t hat will mute the amplifier whenever the tps1035 detects an overcurrent condition. the fault pin (pin 8 of the tps1035) is an overcurrent indicator and is normally high (approximately 5. 4v). when an overcurrent condition is detected this pin will go low (0v). when the fault pin goes low q2 will turn on and pull the mute pin of the tc2001 to 5v (if the switch is closed). this is due to the fact that the emitter voltage of q2 is controlled by the hmute pin of the tc2001 through q1. if hmute is low the emitter voltage of q2 will be connected to the 5v line. if hmute is high q2 is disabled and the mute pin will be pulled low through the 20k ? resistor. in this circuit, whenever the switch is open the mute pi n will be pulled up to 5v and the amplifier will be muted. whenever the mute pin on the tc2001 is high (or enabl ed) the hmute pin will also switch high. the sleep pin of the tps1035 is controlled by hm ute of the tc2001 so that during any mute or overcurrent condition the tps1035 is placed in sleep mode. whenever sleep is enabled, the fault pin is low and mutes the tc2001. q1 contro ls the emitter voltage of q2 through hmute so that whenever the sleep is enabled the tc2001 can become unmuted again. over-temperature protection an over-temperature fault occurs if the juncti on temperature of the tps1035 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 the hmute pin on the tc2001 is a 5v logic output that indicates various fault conditions within the device. these conditions include: over-current, overvoltage and under voltage. the hmute output is high whenever a fault condition occurs or mute is enabled. the hmute pin is capable of directly driving an led through a series 2k ? resistor.
tripath technology, inc. - technical information 18 TK2019 ? mc/2.1/10-03 ovrldb the ovrldb pin is a 5v logic output that is asserted just at the onset of clipping. when low, it indicates that the level of the input signal has ov erloaded the amplifier resulting in increased distortion at the output. the ovrldb signal can be used to cont rol a distortion indicator light or led through a transistor, as the ovrldb cannot dr ive an led directly. there is a 20k resistor on chip in series with the ovrldb output. performance measurements of the TK2019 the TK2019 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 affect ed by the design of the low-pass f ilter 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 TK2019 amplifier switching pattern will degrade the measurement. one feature of the TK2019 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 TK2019 reference 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 19 TK2019 ? mc/2.1/10-03 package information ? tc2001
tripath technology, inc. - technical information 20 TK2019 ? mc/2.1/10-03 package information ? tps1035
tripath technology, inc. - technical information 21 TK2019 ? mc/2.1/10-03 tripath and digital power processing are trademarks of tripath technology inc. other trademarks referenced in this document are ow ned 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. tri path does not assume any liability arising out of the application or use of any product or circuit descri bed herein; neither does it convey any license under its patent rights, nor the rights of others. tripath?s products 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 technology 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 pr ovided in this labeling, can be reasonably expected to result in significant injury to the user. 2. a critical component is any co mponent of a life support device or sy stem whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. for more information on tripath products, visit our web site at: http://www.tripath.com 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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