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650 khz /1.3 mhz step-up pwm dc-to-dc switching converters ADP1612/adp1613 rev. 0 information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 www.analog.com fax: 781.461.3113 ?2009 analog devices, inc. all rights reserved. features current limit 1.4 a for the ADP1612 2.0 a for the adp 1613 minimum input voltage 1.8 v for the ADP1612 2.5 v for the adp1613 pin-selectable 650 khz or 1.3 mhz pwm frequency adjustable output voltage up to 20 v adjustable soft start undervoltage lockout thermal shutdown 8-lead msop applications tft lcd bias supplies portable applications industrial/instrumentation equipment typical application circuit ADP1612/ adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off 1.3mhz 650khz (default) v out v in l1 c in c ss c out c comp r comp r1 r2 d1 06772-001 figure 1. step-up regu lator configuration general description the ADP1612/adp1613 are step-up dc-to-dc switching con- verters with an integrated power switch capable of providing an output voltage as high as 20 v. with a package height of less than 1.1 mm, the ADP1612/adp1613 are optimal for space- constrained applications such as portable devices or thin film transistor (tft) liquid crystal displays (lcds). the ADP1612/adp1613 operate in current mode pulse-width modulation (pwm) with up to 94% efficiency. adjustable soft start prevents inrush currents when the part is enabled. the pin-selectable switching frequency and pwm current-mode architecture allow for excellent transient response, easy noise filtering, and the use of small, cost-saving external inductors and capacitors. other key features include undervoltage lockout (uvlo), thermal shutdown (tsd), and logic controlled enable. the ADP1612/adp1613 are available in the lead-free 8-lead msop. 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-009 v in = 5v f sw = 1.3mhz t a = 25c ADP1612, v out = 12v ADP1612, v out = 15v adp1613, v out = 12v adp1613, v out = 15v figure 2. ADP1612/adp1613 efficiency for various output voltages
ADP1612/adp1613 rev. 0 | page 2 of 28 table of contents features .............................................................................................. 1 applications ....................................................................................... 1 typical application circuit ............................................................. 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications ..................................................................................... 3 absolute maximum ratings ............................................................ 4 thermal resistance ...................................................................... 4 boundary condition .................................................................... 4 esd caution .................................................................................. 4 pin configuration and function descriptions ............................. 5 typical performance characteristics ............................................. 6 theory of operation ...................................................................... 11 current-mode pwm operation .............................................. 11 frequency selection ................................................................... 11 soft start ...................................................................................... 11 thermal shutdown (tsd) ......................................................... 12 undervoltage lockout (uvlo) ............................................... 12 enable/shutdown control ........................................................ 12 applications information .............................................................. 13 setting the output voltage ........................................................ 13 inductor selection ...................................................................... 13 choosing the input and output capacitors ........................... 13 diode selection ........................................................................... 14 loop compensation .................................................................. 14 soft start capacitor .................................................................... 15 typical application circuits ......................................................... 16 step-up regulator ...................................................................... 16 step-up regulator circuit examples ....................................... 16 sepic converter ........................................................................ 22 tft lcd bias supply ................................................................ 22 pcb layout guidelines .................................................................. 24 outline dimensions ....................................................................... 25 ordering guide .......................................................................... 25 revision history 4/09revision 0: initial version
ADP1612/adp1613 rev. 0 | page 3 of 28 specifications v in = 3.6 v, unless otherwise noted. minimum and maximum values are guaranteed for t j = ?40c to +125c. typical values specified are at t j = 25c. all limits at temperature extremes are guaranteed by correlation and characterization using standard statistical quali ty control (sqc), unless otherwise noted. table 1. parameter symbol conditions min typ max unit supply input voltage v in ADP1612 1.8 5.5 v adp1613 2.5 5.5 v quiescent current nonswitching state i q v fb = 1.5 v, freq = v in 900 1350 a v fb = 1.5 v, freq = gnd 700 1300 a shutdown i qshdn v en = 0 v 0.01 2 a switching state 1 i qsw freq = v in , no load 4 5.8 ma freq = gnd, no load 2.2 4 ma enable pin bias current i en v en = 3.6 v 3.3 7 a output output voltage v out v in 20 v load regulation i load = 10 ma to 150 ma, v in = 3.3 v, v out = 12 v 0.1 mv/ma reference feedback voltage v fb 1.2041 1.235 1.2659 v line regulation ADP1612, v in = 1.8 v to 5.5 v; adp1613, v in = 2.5 v to 5.5 v 0.07 0.24 %/v error amplifier transconductance g mea i = 4 a 80 a/v voltage gain a v 60 db fb pin bias current v fb = 1.3 v 1 50 na switch sw on resistance r dson i sw = 1.0 a 130 300 m sw leakage current v sw = 20 v 0.01 10 a peak current limit 2 i cl ADP1612, duty cycle = 70% 0.9 1.4 1.9 a adp1613, duty cycle = 70% 1.3 2.0 2.5 a oscillator oscillator frequency f sw freq = gnd 500 650 720 khz freq = v in 1.1 1.3 1.4 mhz maximum duty cycle d max comp = open, v fb = 1 v, freq = v in 88 90 % freq pin current i freq freq = 3.6 v 5 8 a en/freq logic threshold ADP1612, v in = 1.8 v to 5.5 v; adp1613, v in = 2.5 v to 5.5 v input voltage low v il 0.3 v input voltage high v ih 1.6 v soft start ss charging current i ss v ss = 0 v 3.4 5 6.2 a ss voltage v ss v fb = 1.3 v 1.2 v undervoltage lockout (uvlo) undervoltage lockout threshold ADP1612, v in rising 1.70 v ADP1612, v in falling 1.62 v adp1613, v in rising 2.25 v adp1613, v in falling 2.16 v thermal shutdown thermal shutdown threshold 150 c thermal shutdown hysteresis 20 c 1 this parameter specifies the aver age current while switching internally and with sw (pin 5) floating. 2 current limit is a function of duty cycle. see the section for typical values over operating ranges. typical performance characteristics
ADP1612/adp1613 rev. 0 | page 4 of 28 absolute maximum ratings table 2. parameter rating vin, en, fb to gnd ?0.3 v to +6 v freq to gnd ?0.3 v to v in + 0.3 v comp to gnd 1.0 v to 1.6 v ss to gnd ?0.3 v to +1.3 v sw to gnd 21 v operating junction temperature range ?40c to +125c storage temperature range ?65c to +150c soldering conditions jedec j-std-020 esd (electrostatic discharge) human body model 5 kv stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. absolute maximum ratings apply individually only, not in combination. thermal resistance junction-to-ambient thermal resistance ( ja ) of the package is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. the junction-to- ambient thermal resistance is highly dependent on the application and board layout. in applications where high maximum power dissipation exists, attention to thermal board design is required. the value of ja may vary, depending on pcb material, layout, and environmental conditions. table 3. package type ja jc unit 8-lead msop 2-layer board 1 206.9 44.22 c/w 4-layer board 1 162.2 44.22 c/w 1 thermal numbers per jedec standard jesd 51-7. boundary condition modeled under natural convection cooling at 25c ambient temperature, jesd 51-7, and 1 w power input with 2- and 4-layer boards. esd caution
ADP1612/adp1613 rev. 0 | page 5 of 28 pin configuration and fu nction descriptions comp 1 fb 2 en 3 gnd 4 ss 8 freq 7 vin 6 sw 5 0 6772-002 ADP1612/ adp1613 top view (not to scale) figure 3. pin configuration table 4. pin function descriptions pin o. neonic description 1 comp compensation input. connect a series resistor-capacitor network from comp to gnd to compensate the regulator. 2 fb output voltage feedback input. connect a resistive volt age divider from the output voltage to fb to set the regulator output voltage. 3 en enable input. drive en low to shut down the regulator; drive en high to turn on the regulator. 4 gnd ground. 5 sw switching output. connect the power inductor from the in put voltage to sw and connect the external rectifier from sw to the output voltage to complete the step-up converter. 6 vin main power supply input. vin powers the ADP1612/adp1613 in ternal circuitry. connect vin to the input source voltage. bypass vin to gnd with a 10 f or greater capacitor as close to the ADP1612/adp1613 as possible. 7 freq frequency setting input. freq controls the switching freq uency. connect freq to gnd to program the oscillator to 650 khz, or connect freq to vin to program it to 1.3 mhz. if freq is left floating, the part defaults to 650 khz. 8 ss soft start timing capacitor input. a capacitor connected from ss to gnd brings up the output slowly at power- up and reduces inrush current.
ADP1612/adp1613 rev. 0 | page 6 of 28 typical performance characteristics v en = v in and t a = 25c, unless otherwise noted. 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-012 v in = 3.3v f sw = 650khz t a = 25c v out = 5v v out = 12v v out = 15v ADP1612 figure 4. ADP1612 efficiency vs. load current, v in = 3.3 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-026 v in = 3.3v f sw = 1.3mhz t a = 25c v out = 5v v out = 12v v out = 15v ADP1612 figure 5. ADP1612 efficiency vs. load current, v in = 3.3 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-027 v in = 5v f sw = 650khz t a = 25c v out = 12v v out = 15v ADP1612 figure 6. ADP1612 efficiency vs. load current, v in = 5 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-028 v in = 5v f sw = 1.3mhz t a = 25c v out = 12v v out = 15v ADP1612 figure 7. ADP1612 efficiency vs. load current, v in = 5 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-029 v in = 5v f sw = 650khz t a = 25c v out = 12v v out = 15v v out = 20v adp1613 figure 8. adp1613 efficiency vs. load current, v in = 5 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-030 v in = 5v f sw = 1.3mhz t a = 25c v out = 12v v out = 15v v out = 20v adp1613 figure 9. adp1613 efficiency vs. load current, v in = 5 v, f sw = 1.3 mhz
ADP1612/adp1613 rev. 0 | page 7 of 28 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.8 2.3 2.8 3.3 3.8 4.3 4.8 input voltage (v) current limit (a) 06772-010 ADP1612 t a = +25c t a = +85c t a = ?40c figure 10. ADP1612 switch current limit vs. input voltage, v out = 5 v 2.0 1.8 1.6 1.4 1.2 1.0 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) current limit (a) 06772-013 ADP1612 t a = +25c t a = +85c t a = ?40c figure 11. ADP1612 switch current limit vs. input voltage, v out = 8 v 1.6 1.4 1.2 1.0 0.8 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) current limit (a) 06772-011 ADP1612 t a = +25c t a = ?40c t a = +85c figure 12. ADP1612 switch current limit vs. input voltage, v out = 15 v 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 2.5 3.0 3.5 4.0 4.5 input voltage (v) current limit (a) 06772-031 adp1613 t a = +25c t a = +85c t a = ?40c figure 13. adp1613 switch current limit vs. input voltage, v out = 5 v 2.6 2.4 2.2 2.0 1.8 2.5 3.0 3.5 4.0 input voltage (v) 4.5 5.0 5.5 current limit (a) 06772-032 adp1613 t a = +25c t a = +85c t a = ?40c figure 14. adp1613 switch current limit vs. input voltage, v out = 8 v 2.6 2.4 2.2 2.0 1.8 1.6 1.4 2.5 3.0 3.5 4.0 input voltage (v) 4.5 5.0 5.5 current limit (a) 06772-033 adp1613 t a = +85c t a = +25c t a = ?40c figure 15. adp1613 switch current limit vs. input voltage, v out = 15 v
ADP1612/adp1613 rev. 0 | page 8 of 28 800 750 700 650 600 550 500 450 400 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) quiescent current (a) 06772-014 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 16. ADP1612/adp1613 quiescent current vs. input voltage, nonswitching, f sw = 650 khz 800 750 700 650 600 550 500 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) quiescent current (a) 06772-017 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 17. ADP1612/adp1613 quiescent current vs. input voltage, nonswitching, f sw = 1.3 mhz 3.5 3.0 2.5 2.0 1.5 1.0 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) quiescent current (ma) 06772-015 t a = +25c t a = ?40c t a = +125c ADP1612/adp1613 figure 18. ADP1612/adp1613 quiescent current vs. input voltage, switching, f sw = 650 khz 6 5 4 3 2 1 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) quiescent current (ma) 06772-018 t a = +125c t a = +25c t a = ?40c ADP1612/adp1613 figure 19. ADP1612/adp1613 quiescent current vs. input voltage, switching, f sw = 1.3 mhz 250 230 210 190 170 150 130 110 90 70 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) r dson (m ? ) 06772-016 i sw = 1a t a = ?40c t a = +30c t a = +85c ADP1612/adp1613 figure 20. ADP1612/adp1613 on resistance vs. input voltage 250 230 210 190 170 150 130 110 90 70 ?40 ?15 10 35 60 85 temperature (c) r dson (m ? ) 06772-019 v in = 5.5v i sw = 1a v in = 1.8v v in = 2.5v v in = 3.6v ADP1612/adp1613 figure 21. ADP1612/adp1613 on resistance vs. temperature
ADP1612/adp1613 rev. 0 | page 9 of 28 660 650 640 630 620 610 600 590 580 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) frequency (khz) 06772-020 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 22. ADP1612/adp1613 frequency vs. input voltage, f sw = 650 khz 1.32 1.30 1.28 1.26 1.24 1.22 1.20 1.18 1.16 1.14 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) frequency (mhz) 06772-023 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 23. ADP1612/adp1613 frequency vs. input voltage, f sw = 1.3 mhz 7 6 5 4 3 2 1 0 0 0.51.01.52.02.53.03.54.04.55.05.5 en pin voltage (v) en pin current (a) 06772-021 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 24. ADP1612/adp1613 en pin current vs. en pin voltage 5.1 5.0 4.9 4.8 4.7 4.6 4.5 ?40 ?10 20 50 80 110 temperature (c) ss pin current (a) 06772-024 v in = 1.8v v in = 3.6v v in = 5.5v ADP1612/adp1613 figure 25. ADP1612/adp1613 ss pin current vs. temperature 92.8 92.6 92.4 92.2 92.0 91.8 91.6 91.4 91.2 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) maximum duty cycle (%) 06772-022 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 26. ADP1612/adp1613 maximum duty cycle vs. input voltage, f sw = 650 khz 93.4 93.2 93.0 92.8 92.6 92.4 92.2 92.0 91.8 91.6 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input voltage (v) maximum duty cycle (%) 06772-025 t a = +25c t a = +125c t a = ?40c ADP1612/adp1613 figure 27. ADP1612/adp1613 maximum duty cycle vs. input voltage, f sw = 1.3 mhz
ADP1612/adp1613 rev. 0 | page 10 of 28 06772-034 t time (400ns/div) v in = 5v v out = 12v i load = 20ma l = 6.8h f sw = 1.3mhz c out = 10f output voltage (5v/div) inductor current (200ma/div) switch voltage (10v/div) figure 28. ADP1612/adp1613 switching waveform in discontinuous conduction mode 06772-035 t time (400ns/div) v in = 5v v out = 12v i load = 200ma l = 6.8h f sw = 1.3mhz c out = 10f output voltage (5v/div) inductor current (500ma/div) switch voltage (10v/div) figure 29. ADP1612/adp1613 switching waveform in continuous conduction mode 06772-036 t time (20ms/div) v in = 5v v out = 12v i load = 250ma l = 6.8h f sw = 1.3mhz output voltage (5v/div) inductor current (2a/div) switch voltage (10v/div) en pin voltage (5v/div) figure 30. ADP1612/adp1613 start-up from v in , c ss =33 nf 06772-037 t time (20ms/div) v in = 5v v out = 12v i load = 250ma l = 6.8h f sw = 1.3mhz output voltage (5v/div) switch voltage (10v/div) en pin voltage (5v/div) inductor current (2a/div) figure 31. ADP1612/adp1613 start-up from v in , c ss =100 nf 06772-038 t time (400s/div) v in = 5v v out = 12v i load = 250ma l = 6.8h f sw = 1.3mhz output voltage (5v/div) inductor current (500ma/div) switch voltage (10v/div) en pin voltage (5v/div) figure 32. ADP1612/adp1613 start-up from shutdown, c ss = 33 nf 06772-039 t time (400s/div) v in = 5v v out = 12v i load = 250ma l = 6.8h f sw = 1.3mhz output voltage (5v/div) inductor current (500ma/div) switch voltage (10v/div) en pin voltage (5v/div) figure 33. ADP1612/adp1613 start-up from shutdown, c ss = 100 nf
ADP1612/adp1613 rev. 0 | page 11 of 28 theory of operation freq sw pwm comparator uvlo comparator tsd comparator oscillator s r q d comparator d r e f + + 7 vin current sensing 5a driver band gap n1 bg reset 1.1m ? agnd v in uvlo ref t sense t ref error amplifier v bg soft start 2 1 5a v ss r comp c comp comp ss fb c ss r1 r2 c in v out 6 v in l1 d1 a v out c out 5 3 4 gnd agnd >1.6v en ADP1612/ad1613 06772-003 8 v in <0.3v >1.6v <0.3v figure 34. block diagram with step-up regulator application circuit the ADP1612/adp1613 current-mode step-up switching converters boost a 1.8 v to 5.5 v input voltage to an output voltage as high as 20 v. the internal switch allows a high output current, and the high 650 khz/1.3 mhz switching frequency allows for the use of tiny external components. the switch current is monitored on a pulse-by-pulse basis to limit it to 1.4 a typical (ADP1612) or 2.0 a typical (adp1613). current-mode pwm operation the ADP1612/adp1613 utilize a current-mode pwm control scheme to regulate the output voltage over all load conditions. the output voltage is monitored at fb through a resistive voltage divider. the voltage at fb is compared to the internal 1.235 v reference by the internal transconductance error amplifier to create an error voltage at comp. the switch current is internally measured and added to the stabilizing ramp. the resulting sum is compared to the error voltage at comp to control the pwm modulator. this current-mode regulation system allows fast transient response, while maintaining a stable output voltage. by selecting the proper resistor-capacitor network from comp to gnd, the regulator response is optimized for a wide range of input voltages, output voltages, and load conditions. frequency selection the frequency of the ADP1612/adp1613 is pin-selectable to operate at either 650 khz to optimize the regulator for high efficiency or at 1.3 mhz for use with small external components. if freq is left floating, the part defaults to 650 khz. connect freq to gnd for 650 khz operation or connect freq to vin for 1.3 mhz operation. when connected to vin for 1.3 mhz operation, an additional 5 a, typical, of quiescent current is active. this current is turned off when the part is shutdown. soft start to prevent input inrush current to the converter when the part is enabled, connect a capacitor from ss to gnd to set the soft start period. once the ADP1612/adp1613 are turned on, ss sources 5 a, typical, to the soft start capacitor (c ss ) until it reaches 1.2 v at startup. as the soft start capacitor charges, it limits the peak current allowed by the part. by slowly charging the soft start capacitor, the input current ramps slowly to prevent it from overshooting excessively at startup. when the ADP1612/ adp1613 are in shutdown mode (en 0.3 v), a thermal shut- down event occurs, or the input voltage is below the falling undervoltage lockout voltage, ss is internally shorted to gnd to discharge the soft start capacitor.
ADP1612/adp1613 rev. 0 | page 12 of 28 thermal shutdown (tsd) the ADP1612/adp1613 include tsd protection. if the die temperature exceeds 150c (typical), tsd turns off the nmos power device, significantly reducing power dissipation in the device and preventing output voltage regulation. the nmos power device remains off until the die temperature reduces to 130c (typical). the soft start capacitor is discharged during tsd to ensure low output voltage overshoot and inrush currents when regulation resumes. undervoltage lockout (uvlo) if the input voltage is below the uvlo threshold, the ADP1612/ adp1613 automatically turn off the power switch and place the part into a low power consumption mode. this prevents potentially erratic operation at low input voltages and prevents the power device from turning on when the control circuitry cannot operate it. the uvlo levels have ~100 mv of hysteresis to ensure glitch free startup. enable/shutdown control the en input turns the ADP1612/adp1613 regulator on or off. drive en low to turn off the regulator and reduce the input current to 0.01 a, typical. drive en high to turn on the regulator. when the step-up dc-to-dc switching converter is in shutdown mode (en 0.3 v), there is a dc path from the input to the output through the inductor and output rectifier. this causes the output voltage to remain slightly below the input voltage by the forward voltage of the rectifier, preventing the output voltage from dropping to ground when the regulator is shutdown. figure 37 provides a circuit modification to disconnect the output voltage from the input voltage at shutdown. regardless of the state of the en pin, when a voltage is applied to vin of the ADP1612/adp1613, a large current spike occurs due to the nonisolated path through the inductor and diode between v in and v out . the high current is a result of the output capacitor charging. the peak value is dependent on the inductor, output capacitor, and any load active on the output of the regulator.
ADP1612/adp1613 rev. 0 | page 13 of 28 applications information setting the output voltage the ADP1612/adp1613 feature an adjustable output voltage range of v in to 20 v. the output voltage is set by the resistor voltage divider, r1 and r2, (see figure 34 ) from the output voltage (v out ) to the 1.235 v feedback input at fb. use the following equation to determine the output voltage: v out = 1.235 (1 + r1 / r2 ) (1) choose r1 based on the following equation: ? ? ? ? ? ? ? = 235.1 235.1 out v r2r1 (2) inductor selection the inductor is an essential part of the step-up switching converter. it stores energy during the on time of the power switch, and transfers that energy to the output through the output rectifier during the off time. to balance the tradeoffs between small inductor current ripple and efficiency, induc- tance values in the range of 4.7 h to 22 h are recommended. in general, lower inductance values have higher saturation current and lower series resistance for a given physical size. however, lower inductance results in a higher peak current that can lead to reduced efficiency and greater input and/or output ripple and noise. a peak-to-peak inductor ripple current close to 30% of the maximum dc input current typically yields an optimal compromise. for determining the inductor ripple current in continuous operation, the input (v in ) and output (v out ) voltages determine the switch duty cycle (d) by the following equation: out in out v vv d ? = (3) using the duty cycle and switching frequency, f sw , determine the on time by the following equation: sw on f d t = (4) the inductor ripple current ( i l ) in steady state is calculated by l tv i on in l = (5) solve for the inductance value (l) by the following equation: l on in i tv l = (6) ensure that the peak inductor current (the maximum input current plus half the inductor ripple current) is below the rated saturation current of the inductor. likewise, make sure that the maximum rated rms current of the inductor is greater than the maximum dc input current to the regulator. for ccm duty cycles greater than 50% that occur with input voltages less than one-half the output voltage, slope compen- sation is required to maintain stability of the current-mode regulator. for stable current-mode operation, ensure that the selected inductance is equal to or greater than the minimum calculated inductance, l min , for the application parameters in the following equation: sw in out min f v v ll ? => 7.2 )2( (7) inductors smaller than the 4.7 h to 22 h recommended range can be used as long as equation 7 is satisfied for the given application. for input/output combinations that approach the 90% maximum duty cycle, doubling the inductor is recom- mended to ensure stable operation. table 5 suggests a series of inductors for use with the ADP1612/adp1613. table 5. suggested inductors manufacturer part series dimensions l w h (mm) sumida cmd4d11 5.8 4.4 1.2 cdrh4d28cnp 5.1 5.1 3.0 cdrh5d18np 6.0 6.0 2.0 cdrh6d26hpnp 7.0 7.0 2.8 coilcraft do3308p 12.95 9.4 3.0 do3316p 12.95 9.4 5.21 toko d52lc 5.2 5.2 2.0 d62lcb 6.2 6.3 2.0 d63lcb 6.2 6.3 3.5 wrth elektronik we-tpc assorted we-pd, pd2, pd3, pd4 assorted choosing the input and output capacitors the ADP1612/adp1613 require input and output bypass capa- citors to supply transient currents while maintaining constant input and output voltages. use a low equivalent series resistance (esr), 10 f or greater input capacitor to prevent noise at the ADP1612/adp1613 input. place the capacitor between vin and gnd as close to the ADP1612/adp1613 as possible. ceramic capacitors are preferred because of their low esr characteristics. alternatively, use a high value, medium esr capacitor in parallel with a 0.1 f low esr capacitor as close to the ADP1612/adp1613 as possible.
ADP1612/adp1613 rev. 0 | page 14 of 28 the output capacitor maintains the output voltage and supplies current to the load while the ADP1612/adp1613 switch is on. the value and characteristics of the output capacitor greatly affect the output voltage ripple and stability of the regulator. a low esr ceramic dielectric capacitor is preferred. the output voltage ripple ( v out ) is calculated as follows: out on l out c out c t i c q v == (8) where: q c is the charge removed from the capacitor. t on is the on time of the switch. c out is the output capacitance. i l is the average inductor current. sw on f d t = (9) and out in out v vv d ? = (10) choose the output capacitor based on the following equation: out out sw in out l out vvf vvi c ? ? ) ( (11) multilayer ceramic capacitors are recommended for this application. diode selection the output rectifier conducts the inductor current to the output capacitor and load while the switch is off. for high efficiency, minimize the forward voltage drop of the diode. for this reason, schottky rectifiers are recommended. however, for high voltage, high temperature applications, where the schottky rectifier reverse leakage current becomes significant and can degrade efficiency, use an ultrafast junction diode. ensure that the diode is rated to handle the average output load current. many diode manufacturers derate the current capability of the diode as a function of the duty cycle. verify that the output diode is rated to handle the average output load current with the minimum duty cycle. the minimum duty cycle of the ADP1612/adp1613 is out maxin out min v vv d )( ? = (12) where v in(max) is the maximum input voltage. the following are suggested schottky diode manufacturers: ? on semiconductor ? diodes, inc. loop compensation the ADP1612/adp1613 use external components to compensate the regulator loop, allowing optimization of the loop dynamics for a given application. the step-up converter produces an undesirable right-half plane zero in the regulation feedback loop. this requires compensating the regulator such that the crossover frequency occurs well below the frequency of the right-half plane zero. the right- half plane zero is determined by the following equation: l r v v rhpf load out in z ? ? ? ? ? ? ? ? = 2 )( 2 (13) where: f z (rhp) is the right-half plane zero. r load is the equivalent load resistance or the output voltage divided by the load current. to stabilize the regulator, ensure that the regulator crossover frequency is less than or equal to one-fifth of the right-half plane zero. the regulator loop gain is out cs comp mea out in out fb vl zgzg v v v v a = (14) where: a vl is the loop gain. v fb is the feedback regulation voltage, 1.235 v. v out is the regulated output voltage. v in is the input voltage. g mea is the error amplifier transconductance gain. z comp is the impedance of the series rc network from comp to gnd. g cs is the current sense transconductance gain (the inductor current divided by the voltage at comp), which is internally set by the ADP1612/adp1613. z out is the impedance of the load and output capacitor.
ADP1612/adp1613 rev. 0 | page 15 of 28 to determine the crossover frequency, it is important to note that, at that frequency, the compensation impedance (z comp ) is dominated by a resistor, and the output impedance (z out ) is dominated by the impedance of an output capacitor. therefore, when solving for the crossover frequency, the equation (by definition of the crossover frequency) is simplified to 1 2 1 = = out c cs comp mea out in out fb vl cf grg v v v v a (15) where: f c is the crossover frequency. r comp is the compensation resistor. solve for r comp , cs mea infb out out c comp ggvv vcf r = 2 )( 2 (16) where: v fb = 1.235 v. g mea = 80 a/v. g cs = 13.4 a/v. in out out c comp v vcf r 2 )( 4746 = (17) once the compensation resistor is known, set the zero formed by the compensation capacitor and resistor to one-fourth of the crossover frequency, or comp c comp rf c = 2 (18) where c comp is the compensation capacitor. r comp c comp c2 1 comp g m error amplifier 2 fb v bg 06772-004 figure 35. compensation components the capacitor, c2, is chosen to cancel the zero introduced by output capacitance, esr. solve for c2 as follows: comp out r c esr c2 = (19) for low esr output capacitance such as with a ceramic capacitor, c2 is optional. for optimal transient performance, r comp and c comp might need to be adjusted by observing the load transient response of the ADP1612/adp1613. for most applications, the compensation resistor should be within the range of 4.7 k to 100 k and the compensation capacitor should be within the range of 100 pf to 3.3 nf. soft start capacitor upon startup (en 1.6 v), the voltage at ss ramps up slowly by charging the soft start capacitor (c ss ) with an internal 5 a current source (i ss ). as the soft start capacitor charges, it limits the peak current allowed by the part to prevent excessive over- shoot at startup. the necessary soft start capacitor, c ss , for a specific overshoot and start-up time can be calculated for the maximum load condition when the part is at current limit by: ss ssss v t ic = (20) where: i ss = 5 a (typical). v ss = 1.2 v. t = startup time, at current limit. if the applied load does not place the part at current limit, the necessary c ss will be smaller. a 33 nf soft start capacitor results in negligible input current overshoot at start up, and therefore is suitable for most applications. however, if an unusually large output capacitor is used, a longer soft start period is required to prevent input inrush current. conversely, if fast startup is a requirement, the soft start capacitor can be reduced or removed, allowing the ADP1612/adp1613 to start quickly, but allowing greater peak switch current .
ADP1612/adp1613 rev. 0 | page 16 of 28 typical application circuits both the ADP1612 and adp1613 can be used in the application circuits in this section. the ADP1612 is geared toward applications requiring input voltages as low as 1.8 v, where the adp1613 is more suited for applications needing the output power capabilities of a 2.0 a switch. the primary differences are shown in table 6 . table 6. ADP1612/adp1613 differences parameter ADP1612 adp1613 current limit 1.4 a 2.0 a input voltage range 1.8 v to 5.5 v 2.5 v to 5.5 v the step-up regulator circuit examples section recommends component values for several common input, output, and load conditions. the equations in the applications information section can be used to select components for alternate configurations. step-up regulator the circuit in figure 36 shows the ADP1612/adp1613 in a basic step-up configuration. ADP1612/ adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off 1.3mhz 650khz (default) v out v in l1 c in c ss c out c comp r comp r1 r2 d1 06772-005 figure 36. step-up regulator the modified step-up circuit in figure 37 incorporates true shutdown capability advantageous for battery-powered applica- tions requiring low standby current. driving the en pin below 0.3 v shuts down the ADP1612/adp1613 and completely disconnects the input from the output. ADP1612/ adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd 1.3mhz 650khz (default) v out l1 c in c ss c out c comp r comp r1 r2 d1 06772-006 v in r3 10k? ntgd1100l q1 a b q1 on off figure 37. step-up regulator with true shutdown step-up regulator circuit examples ADP1612 step-up regulator 06772-040 ADP1612 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 5v v in = 1.8v to 4.2v l1 4.7h c ss 33nf c out 10f c comp 3300pf r comp 6.8k ? r1 30k? r2 10k? d1 3a, 40v c in 10f l1: do3316p-472ml d1: mbra340t3g r1: rc0805fr-0730kl r2: crcw080510k0fkea r comp : rc0805jr-076k8l c comp : ecj-2vb1h332k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 38. ADP1612 step-up regulator configuration v out = 5 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k 10k load current (ma) efficiency (%) 06772-041 v out = 5v f sw = 650khz t a = 25c v in = 1.8v v in = 2.7v v in = 3.3v v in = 4.2v ADP1612 figure 39. ADP1612 efficiency vs. load current v out = 5 v, f sw = 650 khz 06772-042 v out = 5v f sw = 650khz t time (100s/div) output voltage (50mv/div) ac-coupled load current (50ma/div) figure 40. ADP1612 50 ma to 150 ma load transient (v in = 3.3 v) v out = 5 v, f sw = 650 khz
ADP1612/adp1613 rev. 0 | page 17 of 28 06772-043 ADP1612 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 5v v in = 1.8v to 4.2v l1 4.7h c ss 33nf c out 10f c comp 1200pf r comp 12k ? r1 30k? r2 10k? c in 10f l1: do3316p-472ml d1: mbra340t3g r1: rc0805fr-0730kl r2: crcw080510k0fkea r comp : rc0805jr-0712kl c comp : ecj-2vb1h122k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k d1 3a, 40v figure 41. ADP1612 step-up regulator configuration v out = 5 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 1 10 100 1k 10k load current (ma) efficiency (%) 06772-044 v out = 5v f sw = 1.3mhz t a = 25c v in = 1.8v v in = 2.7v v in = 3.3v v in = 4.2v ADP1612 figure 42. ADP1612 efficiency vs. load current v out = 5 v, f sw = 1.3 mhz 06772-045 v out = 5v f sw = 1.3mhz t time (100s/div) output voltage (50mv/div) ac-coupled load current (50ma/div) figure 43. ADP1612 50 ma to 150 ma load transient (v in = 3.3 v) v out = 5 v, f sw = 1.3 mhz 06772-046 ADP1612 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 12v v in = 2.7v to 5v l1 10h c ss 33nf c out 10f c comp 1800pf r comp 22k ? r1 86.6k ? r2 10k? d1 2a, 20v c in 10f l1: do3316p-103ml d1: dfls220l-7 r1: erj-6enf8662v r2: crcw080510k0fkea r comp : rc0805jr-0722kl c comp : ecj-2vb1h182k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 44. ADP1612 step-up regulator configuration v out = 12 v, f sw = 650 khz 100 90 80 70 60 50 40 1 10 100 1k load current (ma) efficiency (%) 06772-047 v in = 12v f sw = 650khz t a = 25c ADP1612 v in = 2.7v v in = 3.3v v in = 4.2v v in = 5.0v figure 45. ADP1612 efficiency vs. load current v out = 12 v, f sw = 650 khz 06772-048 v out = 12v f sw = 650khz t time (100s/div) output voltage (100mv/div) ac-coupled load current (50ma/div) figure 46. ADP1612 50 ma to 150 ma load transient (v in = 3.3 v) v out = 12 v, f sw = 650 khz
ADP1612/adp1613 rev. 0 | page 18 of 28 06772-049 ADP1612 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 12v v in = 2.7v to 5v l1 6.8h c ss 33nf c out 10f c comp 680pf r comp 18k ? r1 86.6k ? r2 10k? d1 2a, 20v c in 10f l1: do3316p-682ml d1: dfls220l-7 r1: erj-6enf8662v r2: crcw080510k0fkea r comp : rc0805jr-0718kl c comp : cc0805krx7r9bb681 c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 47. ADP1612 step-up regulator configuration v out = 12 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-050 v in = 12v f sw = 1.3mhz t a = 25c v in = 2.7v v in = 3.3v v in = 4.2v v in = 5.0v ADP1612 figure 48. ADP1612 efficiency vs. load current v out = 12 v, f sw = 1.3 mhz 06772-051 v out = 12v f sw = 1.3mhz t time (100s/div) output voltage (100mv/div) ac-coupled load current (50ma/div) figure 49. ADP1612 50 ma to 150 ma load transient (v in = 3.3 v) v out = 12 v, f sw = 1.3 mhz 06772-052 ADP1612 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 15v v in = 2.7v to 5v l1 15h c ss 33nf c out 10f c comp 1800pf r comp 22k ? r1 110k ? r2 10k? d1 2a, 20v c in 10f l1: do3316p-153ml d1: dfls220l-7 r1: erj-6enf1103v r2: crcw080510k0fkea r comp : rc0805jr-0722kl c comp : ecj-2vb1h182k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 50. ADP1612 step-up regulator configuration v out = 15 v, f sw = 650 khz 100 90 80 70 60 50 40 1 10 100 1k load current (ma) efficiency (%) 06772-053 v in = 15v f sw = 650khz t a = 25c ADP1612 v in = 2.7v v in = 3.3v v in = 4.2v v in = 5.0v figure 51. ADP1612 efficiency vs. load current v out = 15 v, f sw = 650 khz 06772-054 v out = 15v f sw = 650khz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 52. ADP1612 50 ma to 150 ma load transient (v in = 3.3 v) v out = 15 v, f sw = 650 khz
ADP1612/adp1613 rev. 0 | page 19 of 28 06772-055 ADP1612 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 15v v in = 2.7v to 5v l1 10h c ss 33nf c out 10f c comp 1800pf r comp 10k ? r1 110k ? r2 10k? d1 2a, 20v c in 10f l1: do3316p-103ml d1: dfls220l-7 r1: erj-6enf1103v r2: crcw080510k0fkea r comp : rc0805jr-0710kl c comp : ecj-2vb1h182k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 53. ADP1612 step-up regulator configuration v out =15 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-056 v in = 15v f sw = 1.3mhz t a = 25c ADP1612 v in = 2.7v v in = 3.3v v in = 4.2v v in = 5.0v figure 54. ADP1612 efficiency vs. load current v out =15 v, f sw = 1.3 mhz 06772-057 v out = 15v f sw = 1.3mhz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 55. ADP1612 50 ma to 150 ma load transient (v in = 3.3 v) v out =15 v, f sw = 1.3 mhz adp1613 step-up regulator 06772-058 adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 12v v in = 2.7v to 5v l1 10h c ss 33nf c out 10f c comp 2200pf r comp 12k ? r1 86.6k ? r2 10k? d1 3a, 40v c in 10f l1: do3316p-103ml d1: mbra340t3g r1: erj-6enf8662v r2: crcw080510k0fkea r comp : rc0805jr-0712kl c comp : ecj-2vb1h222k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 56. adp1613 step-up regulator configuration v out = 12 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-059 v in = 12v f sw = 650khz t a = 25c adp1613 v in = 2.7v v in = 3.3v v in = 4.2v v in = 5.0v figure 57. adp1613 efficiency vs. load current v out = 12 v, f sw = 650 khz 06772-060 v out = 12v f sw = 650khz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 58. adp1613 50 ma to 150 ma load transient (v in = 5 v) v out = 12 v, f sw = 650 khz
ADP1612/adp1613 rev. 0 | page 20 of 28 06772-061 adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 12v v in = 2.7v to 5v l1 6.8h c ss 33nf c out 10f c comp 1000pf r comp 10k ? r1 86.6k ? r2 10k? d1 3a, 40v c in 10f l1: do3316p-682ml d1: mbra340t3g r1: erj-6enf8662v r2: crcw080510k0fkea r comp : rc0805jr-0710kl c comp : ecj-2vb1h102k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 59. adp1613 step-up regulator configuration v out = 12 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-062 v in = 12v f sw = 1.3mhz t a = 25c adp1613 v in = 2.7v v in = 3.3v v in = 4.2v v in = 5.0v figure 60. adp1613 efficiency vs. load current v out = 12 v, f sw = 1.3 mhz 06772-063 v out = 12v f sw = 1.3mhz t time (100s/div) output voltage (100mv/div) ac-coupled load current (50ma/div) figure 61. adp1613 50 ma to 150 ma load transient (v in = 5 v) v out = 12 v, f sw = 1.3 mhz 06772-064 adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 15v v in = 3.3v to 5.5v l1 15h c ss 33nf c out 10f c comp 1800pf r comp 10k ? r1 110k ? r2 10k? d1 3a, 40v c in 10f l1: do3316p-153ml d1: mbra340t3g r1: erj-6enf1103v r2: crcw080510k0fkea r comp : rc0805jr-0710kl c comp : ecj-2vb1h182k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 62. adp1613 step-up regulator configuration v out = 15 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-065 v in = 15v f sw = 650khz t a = 25c adp1613 v in = 3.3v v in = 4.2v v in = 5.0v v in = 5.5v figure 63. adp1613 efficiency vs. load current v out = 15 v, f sw = 650 khz 06772-066 v out = 15v f sw = 650khz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 64. adp1613 50 ma to 150 ma load transient (v in = 5 v) v out = 15 v, f sw = 650 khz
ADP1612/adp1613 rev. 0 | page 21 of 28 06772-067 adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 15v v in = 3.3v to 5.5v l1 10h c ss 33nf c out 10f c comp 1200pf r comp 8.2k ? r1 110k ? r2 10k? d1 3a, 40v c in 10f l1: do3316p-103ml d1: mbra340t3g r1: erj-6enf1103v r2: crcw080510k0fkea r comp : rc0805jr-078k2l c comp : ecj-2vb1h122k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 65. adp1613 step-up regulator configuration v out = 15 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 20 1 10 100 1k load current (ma) efficiency (%) 06772-068 v in = 15v f sw = 1.3mhz t a = 25c adp1613 v in = 3.3v v in = 4.2v v in = 5.0v v in = 5.5v figure 66. adp1613 efficiency vs. load current v out = 15 v, f sw = 1.3 mhz 06772-069 v out = 15v f sw = 1.3mhz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 67. adp1613 50 ma to 150 ma load transient (v in = 5 v) v out = 15 v, f sw = 1.3 mhz 06772-070 adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 20v v in = 3.3v to 5.5v l1 15h c ss 33nf c out 10f c comp 820pf r comp 18k ? r1 150k ? r2 10k? d1 3a, 40v c in 10f l1: do3316p-153ml d1: mbra340t3g r1: rc0805jr-07150kl r2: crcw080510k0fkea r comp : rc0805jr-0718kl c comp : cc0805krx7r9bb821 c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 68. adp1613 step-up regulator configuration v out = 20 v, f sw = 650 khz 100 90 80 70 60 50 40 30 1 10 100 1k load current (ma) efficiency (%) 06772-071 v in = 20v f sw = 650khz t a = 25c adp1613 v in = 3.3v v in = 4.2v v in = 5.0v v in = 5.5v figure 69. adp1613 efficiency vs. load current v out = 20 v, f sw = 650 khz 06772-072 v out = 20v f sw = 650khz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 70. adp1613 50 ma to 150 ma load transient (v in = 5 v) v out = 20 v, f sw = 650 khz
ADP1612/adp1613 rev. 0 | page 22 of 28 sepic converter 06772-073 adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 20v v in = 3.3v to 5.5v l1 10h c ss 33nf c out 10f c comp 1200pf r comp 8.2k ? r1 150k ? r2 10k? d1 3a, 40v c in 10f l1: do3316p-103ml d1: mbra340t3g r1: rc0805jr-07150kl r2: crcw080510k0fkea r comp : rc0805jr-078k2l c comp : ecl-2vb1h122k c in : grm21br61c106ke15l c out : grm32dr71e106ka12l c ss : ecj-2vb1h333k figure 71. adp1613 step-up regulator configuration v out = 20 v, f sw = 1.3 mhz 100 90 80 70 60 50 40 30 20 1 10 100 1k load current (ma) efficiency (%) 06772-074 v in = 20v f sw = 1.3mhz t a = 25c adp1613 v in = 3.3v v in = 4.2v v in = 5.0v v in = 5.5v figure 72. adp1613 efficiency vs. load current v out = 20 v, f sw = 1.3 mhz 06772-075 v out = 20v f sw = 1.3mhz t time (100s/div) output voltage (200mv/div) ac-coupled load current (50ma/div) figure 73. adp1613 50 ma to 150 ma load transient (v in = 5 v) v out = 20 v, f sw = 1.3 mhz the circuit in figure 74 shows the ADP1612/adp1613 in a single-ended primary inductance converter (sepic) topology. this topology is useful for an unregulated input voltage, such as a battery-powered application in which the input voltage can vary between 2.7 v to 5 v and the regulated output voltage falls within the input voltage range. the input and the output are dc isolated by a coupling capacitor (c1). in steady state, the average voltage of c1 is the input voltage. when the ADP1612/adp1613 switch turns on and the diode turns off, the input voltage provides energy to l1 and c1 provides energy to l2. when the ADP1612/adp1613 switch turns off and the diode turns on, the energy in l1 and l2 is released to charge the output capacitor (c out ) and the coupling capacitor (c1) and to supply current to the load. ADP1612/ adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off v out = 3.3v v in = 2.0v to 5.5v l1 do3316p 4.7h c in 10f c ss c out 10f c1 10f r comp 82k? c comp 220pf r1 16.9k ? l2 do3316p 4.7h r2 10k? mbra210lt 2a, 10v 0 6772-008 figure 74. sepic converter tft lcd bias supply figure 75 shows a power supply circuit for tft lcd module applications. this circuit has +10 v, ?5 v, and +22 v outputs. the +10 v is generated in the step-up configuration. the ?5 v and +22 v are generated by the charge-pump circuit. during the step-up operation, the sw node switches between +10 v and ground (neglecting the forward drop of the diode and on resistance of the switch). when the sw node is high, c5 charges up to +10 v. when the sw node is low, c5 holds its charge and forward-biases d8 to charge c6 to ?10 v. the zener diode (d9) clamps and regulates the output to ?5 v. the vgh output is generated in a similar manner by the charge- pump capacitors, c1, c2, and c4. the output voltage is tripled and regulated down to 22 v by the zener diode, d5.
ADP1612/adp1613 rev. 0 | page 23 of 28 do3316p 4.7h 06772-007 c1 10nf c4 10nf d3 d2 d5 d4 c5 10nf c6 10f d8 d7 r4 200 ? d9 bzt52c5vis vgl ?5v r3 200? c3 10f d5 bzt52c22 c2 1f b a v 99 bav99 bav99 ADP1612/ adp1613 6 3 7 8 5 2 1 4 vin en freq ss sw fb comp gnd on off 1.3mhz 650khz (default) v out = 10v v in = 3.3v c in 10f c ss c out 10f c comp 1200pf r comp 27k ? r1 71.5k ? r2 10k ? d1 vgh +22v figure 75. tft lcd bias supply
ADP1612/adp1613 rev. 0 | page 24 of 28 pcb layout guidelines 06772-076 for high efficiency, good regulation, and stability, a well- designed printed circuit board layout is required. use the following guidelines when designing printed circuit boards (also see figure 34 for a block diagram and figure 3 for a pin configuration). ? keep the low esr input capacitor, c in (labeled as c7 in figure 76 ), close to vin and gnd. this minimizes noise injected into the part from board parasitic inductance. ? keep the high current path from c in (labeled as c7 in figure 76 ) through the l1 inductor to sw and gnd as short as possible. ? keep the high current path from vin through l1, the rectifier (d1) and the output capacitor, c out (labeled as c4 in figure 76 ) as short as possible. ? keep high current traces as short and as wide as possible. ? place the feedback resistors as close to fb as possible to prevent noise pickup. connect the ground of the feedback network directly to an agnd plane that makes a kelvin connection to the gnd pin. figure 76. example layout for ADP1612/adp1613 boost application (top layer) ? place the compensation components as close as possible to comp. connect the ground of the compensation network directly to an agnd plane that makes a kelvin connection to the gnd pin. 06772-077 ? connect the softstart capacitor, c ss (labeled as c1 in figure 76 ) as close to the device as possible. connect the ground of the softstart capacitor to an agnd plane that makes a kelvin connection to the gnd pin. ? avoid routing high impedance traces from the compensa- tion and feedback resistors near any node connected to sw or near the inductor to prevent radiated noise injection. figure 77. example layout for ADP1612/adp1613 boost application (bottom layer)
ADP1612/adp1613 rev. 0 | page 25 of 28 outline dimensions compliant to jedec standards mo-187-aa 0.80 0.60 0.40 8 0 4 8 1 5 pin 1 0.65 bsc seating plane 0.38 0.22 1.10 max 3.20 3.00 2.80 coplanarity 0.10 0.23 0.08 3.20 3.00 2.80 5.15 4.90 4.65 0.15 0.00 0.95 0.85 0.75 figure 78. 8-lead mini small outline package [msop] (rm-8) dimensions shown in millimeters ordering guide model temperature range package desc ription package option branding ADP1612armz-r7 1 ?40c to +85c 8-lead mini small outline package [msop] rm-8 l7z adp1613armz-r7 1 ?40c to +85c 8-lead mini small outline package [msop] rm-8 l96 ADP1612-5-evalz 1 evaluation board, 5 v output voltage configuration adp1613-12-evalz 1 evaluation board, 12 v output voltage configuration 1 z = rohs compliant part.
ADP1612/adp1613 rev. 0 | page 26 of 28 notes
ADP1612/adp1613 rev. 0 | page 27 of 28 notes
ADP1612/adp1613 rev. 0 | page 28 of 28 notes ?2009 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d06772-0-4/09(0)

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