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si9174 vishay siliconix document number: 71668 s-41148?rev. c, 14-jun-04 www.vishay.com 1 high performance step-down dc-dc converter with dynamically adjustable output voltage features 2-mhz pwm operation integrated mosfet switches 2.6-v to 6.0-v input voltage range minimal number of external components up to 96% conversion efficiency 600-ma load capability 100% duty cycle allows low dropout integrated compensation circuit over-current protection shutdown current < 2 a thermal shutdown integrated uvlo 10-pin msop and space saving mlp33 packaging dac input for dynamic output voltage adjustment synchronizable to13-mhz clock user selectable pwm, psm, or auto mode psm frequency 20 khz for inaudible harmonics applications w-cdma cell phone pdas/palmtop pcs lcd modules portable image scanners gps receivers smart phones mp3 players 3g cell phone digital cameras description the si9174 is a high efficiency 600-ma step down converter with internal low on resistance power mosfet switch and synchronous rectifier transistors. it is designed to convert one cell liion battery or three cell alkaline battery voltages to a dynamically adjustable dc output. the voltage on the dac pin controls the output voltage. the output voltage is adjustable between 0.4 v and the input voltage v in less a small dropout voltage and settles in <30 s. in order to insure efficient conversion throughout the entire load range, pwm (pulse width modulation), psm (pulse skipping mode) or auto mode can be selected. in pwm mode, 2-mhz switching permits use of small external inductor and capacitor sizes allowing one of the smallest solutions . to minimize system noise, the switching frequency can be synchronized to an external 13-mhz clock. psm mode provides increased efficiency at light loads. in psm mode the oscillator frequency is kept above 20 khz to avoid audio band interference. when operating in auto mode, the converter automatically selects operating in either pwm or psm mode according to load current demand. the si9174 is available in the10-pin msop and the even smaller mlp33 package and is specified to operate over the industrial temperature range of ?40 c to 85 c. the si9174 packaged in the mlp33 package is available in both standard and lead (pb)-free. typical applications circuit pwm/psm/auto enable dac 13 mhz battery lx v in sync dac sd mode pgnd fb agnd v out si9174 2.2 h c out 4.7 f c in 10 f v dd r 2 r 1
si9174 vishay siliconix www.vishay.com 2 document number: 71668 s-41148?rev. c, 14-jun-04 absolute maximum ratings voltages referenced to agnd = 0 v v in, v dd 6.2 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . lx, sd , mode, fb, dac, sync ? 0.3 to 6.2 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (or to v dd 0.3 v whichever is less) gnd ? 0.3 to +0.3 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . esd rating 2 kv . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . storage temperature ? 65 to 125 c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . operating junction temperature 150 c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . power dissipation (package) a 10-pin msop b 481 mw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-pin mlp33 915 mw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . thermal impedance ( ja ) 10-pin msop 135 c/w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-pin mlp33 71 c/w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . peak inductor current 1.8 a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . notes a. device mounted with all leads soldered or welded to pc board. b. derate 7.4 mw/ c above 85 c. c. derate 14 mw/ c above 85 c. stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. recommended operating range v in range 2.6 v to 5.5 v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c in 10 f ceramic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . c out 4.7 f ceramic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . inductor 2.2 h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . operating load current pwm mode 0 to 600 ma . . . . . . . . . . . . . . . . . . . . . . operating load current psm mode 0 to 150 ma . . . . . . . . . . . . . . . . . . . . . . . specifications parameter test conditions unless specified 40 c to 85 c v in = v dd v dac = 1 215 v c in = 10 f limits mode f symbol ? 40 c to 85 c, v in = v dd, v dac = 1.215 v, c in = 10 f, c out = 4.7 f, l = 2.2 h, 2.6 v v in 5.5 v r 1 = 11.3 k , r 2 = 20 k min a typ b max a unit under voltage lockout (uvlo) under voltage lockout (turn-on) v in rising 2.3 2.5 v hysteresis 0.1 v shutdown (sd) logic high v sdh 1.6 v logic low v sdl 0.4 v delay to output c t settle within 2% accurac y sd risin g r l = 3.3 100 s delay to output c t en settle within 2% accuracy sd rising t r < 1 s r l = 51 100 s pull down i sd input at v in a mode selection tri-level logic (mode) mode pin high pwm v in ? 0.4 v in v mode pin low auto 0.4 v mode pin input current mode = gnd ? 5 a mode pin input current mode = v in 5 a oscillator frequency f osc 1.6 2 2.4 mhz external clock synchronization (sync) frequency sync input = 500 mv p-p 13 mhz ac coupled sinewave frequency = 13 mhz 0.2 0.8 v p-p error amplifier (fb, dac pin) fb voltage accuracy v dac ? 20 v dac +20 mv dac input voltage range v in > 2.6, v in ? v dac > 0.5 v 0.28 2.45 v input bias current fb, dac i fbdac v fb = 1.25 v ? 1 0.01 1 a
si9174 vishay siliconix document number: 71668 s-41148?rev. c, 14-jun-04 www.vishay.com 3 specifications parameter limits test conditions unless specified ? 40 c to 85 c, v in = v dd, v dac = 1.215 v, c in = 10 f, c out = 4.7 f, l = 2.2 h, 2.6 v v in 5.5 v r 1 = 11.3 k , r 2 = 20 k unit max a typ b min a test conditions unless specified ? 40 c to 85 c, v in = v dd, v dac = 1.215 v, c in = 10 f, c out = 4.7 f, l = 2.2 h, 2.6 v v in 5.5 v r 1 = 11.3 k , r 2 = 20 k symbol mode f converter operation maximum output current pwm i load v in = 3.6 v 600 ma maximum output current psm i load v in = 3.6 v 150 ma dropout voltage e v dd v in = 2.6 v, i out = 600 ma 190 300 mv closed loop bandwidth bw 300 khz load regulation c pwm v in = 3.6 v i out = 30 ma to 600 ma 0.5 % load regulation c psm v in = 3 . 6 v v out = 1.9 v @ 25 c i out = 30 ma to 75 ma 0.25 % line regulation pwm v out = 3 0 v v in = 3 5 v to 5 5 v 0.1 %/v line regulation psm v out = 3.0 v, v in = 3.5 v to 5.5 v 0.1 %/v pwm/psm switch threshold current i aupk 200 maximum inductor peak current limit i lpk 1500 ma maximum nmos transistor current sink pwm negative transition on v dac 1500 ma on resistance p-channel r ds( ) v in = 3 6 v 250 m on resistance n-channel r ds(on) v in = 3.6 v 250 m output ripple voltage pwm 0 05 c out(esr) i out = 600 ma 60 mv output ripple voltage psm 0.05 c out(esr) i out = 30 ma 80 mv p-p efficiency pwm v in = 3 6 v v out = 3 3 v i out = 600 ma 90 % efficiency psm v in = 3.6 v, v out = 3.3 v i out = 30 ma 80 % frequency psm i out 30 ma 20 khz supply current input supply current pwm i supply (v dd & i out = 0 ma v in = 3 6 v (not switching fb = gnd) 500 800 input supply current psm (v dd & v in ) i out = 0 ma, v in = 3.6 v (not switching, fb = gnd) 400 a shutdown supply current i sd sd = low 2 thermal shutdown thermal shutdown temperature c t j(s/d) 165 c thermal hysteresis c 20 c notes a. the algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data s heet. b. typical values are for design aid only, not guaranteed or subject to production testing. c. guaranteed by design. d. settling times, t s , apply after t en . e. bypass is a device mode of operation, in which, the device is in 100% duty cycle. bypass operation is possible in either pwm or psm. f. operating modes are controlled with the mode pin where auto mode = mode = low, pwm mode = mode = high, and psm mode = mode = open.
si9174 vishay siliconix www.vishay.com 4 document number: 71668 s-41148?rev. c, 14-jun-04 pin configuration 10 l x pgnd fb sync msop-10 agnd v in 1 2 3 9 8 dac mode top view 56 v dd sd 47 2 3 4 10 9 8 7 l x agnd fb v dd pgnd v in sync sd top view 5 dac 6 mode mlp33 pin description pin number name function 1 l x inductor connection 2 agnd low power analog ground 3 fb output voltage feedback 4 v dd input supply voltage for the analog circuit. 5 dac voltage from external dac to adjust output voltage. 6 mode used to select switching mode of the buck converter pwm/psm pin logic: mode pin operating mode v in pwm open psm gnd auto 7 sd logic low disables ic and reduces quiescent current to below 2 a 8 sync converter switching frequency can be synchronized to 1 / 6 of the clock frequency at this pin. 9 v in input supply voltage 10 pgnd low impedance power ground ordering information msop-10 mlp33 standard part number marking temperature standard part number lead (pb)-free part number marking temperature SI9174DH-T1 9174 ? 40 to 85 c si9174dm-t1 si9174dm-t1?e3 9174 ? 40 to 85 c additional voltage options are available. eval kit temperature range board si9174db ? 40 to 85 c surface mount
si9174 vishay siliconix document number: 71668 s-41148?rev. c, 14-jun-04 www.vishay.com 5 functional block diagram ? + error amplifier ? + pwm comparator voltage reference uvlo 2 mhz oscillator to ic bias pwm and pulse skipping logic pmos current sense v dd v in fb agnd mode sd pgnd l x 2 mhz oscillator 6 sync clamp nmos current sense dac si9174 detail description general the si9174 is a high efficiency synchronous dc-dc converter that is ideally suited for lithium ion battery or three cell alkaline applications, as well as step-down of 3.3-v or 5.0-v supplies. it is design to provide power to the power amplifier in wcdma cell phones, but can utilized in any applications requiring a dynamically adjustable 600-ma power supply. the major blocks of the si9174 are shown in the functional block diagram. the 0.25- internal mosfets switching at a frequency of 2-mhz minimize pc board space while providing high conversion efficiency and performance. the high frequency error-amplifier with built-in loop compensation minimizes external components and provides rapid output settling times of <30 s. sensing of the inductor current for control is accomplished internally without power wasting resistors. the switching frequency can be synchronized to an external 13-mhz clock signal. start-up when voltage is applied to v in and v dd , the under-voltage lockout (uvlo) circuit prevents the oscillator and control circuitry from turning on until the voltage on the exceeds 2.4 v. with a typical uvlo hysteresis of 0.1 v, the converter operates continuously until the voltage on v in drops below 2.3 v, whereupon the converter shuts down. this hysteresis prevents false start-stop cycling as the input voltage approaches the uvlo switching threshold. start-up is always accomplished in pwm mode to ensure start-up under all load conditions. switching to other modes of operation occurs according to the state of the mode pin and the load current. the start-up sequence occurs after sd switches from low to high with v in applied, or after v in rises above the uvlo threshold and sd is a logic high. mode control (mode) the mode pin allows the user to control the mode of operation or to enable the si9174 to automatically optimize the mode of operation according to load current. there are three different modes of operation as controlled by the mode pin. switching waveforms are shown in the typical switching waveform sections, page 9. pwm mode (mode pin = high) with the mode pin in the logic high condition, the si9174 operates as a 2-mhz fixed frequency voltage mode converter. a nmos synchronous rectification mosfet transistor provides very high conversion efficiency for large load currents by minimizing the conduction losses. pwm mode provides low output ripple, fast transient response, and switching frequency synchronization. output load currents can range from 0 to 600 ma.
si9174 vishay siliconix www.vishay.com 6 document number: 71668 s-41148?rev. c, 14-jun-04 the error amplifier and comparator control the duty cycle of the pmos mosfet to continuously force the dac pin and fb pin voltages to be equal. as the input-to-output voltage dif ference drops, the duty cycle of the pmos mosfet can reach 100% to allow system designers to extract the maximum stored energy from the battery. the dropout voltage is 190 mv at 600 ma. during each cycle, the pmos switch current is limited to a maximum of 1.5 a (typical) thereby protecting the ic while continuing to force maximum current into the load. similarly, the nmos switch is internally limited to a maximum of 1.5 a (typical) during negative output voltage transients. pulse skipping mode (mode pin = open) by leaving the mode pin open-circuit, the converter runs in pulse skipping mode (psm). in psm mode the oscillator continues to operate, but switching only occurs if the fb pin voltage is below the dac voltage at the start of each clock cycle. clock cycles are skipped thereby reducing the switching frequency to well below 100 khz and minimizing switching losses for improved efficiency at loads under 150 ma. although psm mode switching frequency varies with line and load conditions, the minimum psm frequency will be kept above 20 khz for load currents of 30 ma or more to prevent switching noise from reaching the audio frequency range. each time the pmos switch is turned on, the inductor current is allowed to reach 300 ma. once achieved, the pmos switch is turned off and the nmos switch is turned on in the normal manner. however, unlike pwm mode, the nmos switch, turns off as the switch current approaches zero current to maximize efficiency. the pmos switch remains on continuously (100% duty cycle) when the input-voltage-to-output-voltage difference is low enabling maximum possible energy extraction from the battery. psm mode is recommend for load currents of 150 ma or less. auto mode when the mode pin grounded, the converter is set to auto mode. switching between pwm mode and psm modes takes place automatically without an external control signal. for heavy load operation, the converter will operate in pwm mode to achieve maximum efficiency. when delivering light load currents, the converter operates in psm mode to conserve power. the switchover threshold between the two modes is determined by the peak inductor current, which is 300 ma nominal. there is hysteresis in the switchover threshold to provide smooth operation. thus, the mode psm-to-pwm mode switchover current for increasing load currents is hi gher than that of pwm-to-psm mode switchover for decreasing load currents. oscillator synchronization (sync) the internal oscillator provides for a fixed 2-mhz switching frequency. in order to minimize system noise, the oscillator of the si9174 can be synchronized to an external clock, typically an ac-coupled 13-mhz sine wave. an on-chip divide-by-six circuit sets the converter switching frequency to 2.167 mhz in this mode. the frequency lock range of the synchronization circuitry is typically 20%. if synchronization is not required, the sync pin must be tied to gnd permitting the internal oscillator to oscillate at 2 mhz. dynamic output voltage control (dac) the si9174 is designed to dynamically adjust the output voltage according to the voltage present on the dac pin. the output voltage is regulated to the same voltage the dac pin through the resistor divider. for v dac within the voltage range of 0.28 ? 2.45 v, v out is proportional to v dac according to the following relationship: v out 1 r 1 r 2
v dac converter shutdown (sd pin) with logic low level on the sd pin, the si9174 is shutdown. shutdown reduces current consumption to less than 2- a by shutting off all of the internal circuits. both the pmos and nmos transistors are turned off. a logic high enables the ic to start up as described in ?start-up? section. thermal shutdown the si9174 includes thermal shutdown circuitry, which turns off the regulator when the junction temperature exceeds 165 c. once the junction temperature drops below 145 c, the regulator is enabled. if the condition causing the over temperature, the si9174 begins thermal cycling, turning the regulator on and off in response to junction temperature. restart from a thermal shutdown condition is the same as described in the ?start-up? section.
si9174 vishay siliconix document number: 71668 s-41148?rev. c, 14-jun-04 www.vishay.com 7 applications circuit pwm/psm/auto enable dac 13 mhz batt lx v in sync dac sd mode pgnd fb agnd v out si9174 2.2 h c out 4.7 f c in 10 f v dd r 2 r 1 c 2 c 1 c in = 10 f, ceramic, murata grm42-2x5r106k16 c 1 , c 2 = 0.01 f, vishay vj0603y 104kxxat c out = 4.7 f, ceramic, murata grm42-6x5r475k16 r 1 = 8.2 k , vishay crcw06031132f r 2 = 20 k , vishay crcw06032002f l 1 = 2.2 h, toko a914byw -2r2m typical characteristics v out 3.83 0.44 0.28 2.45 v dac figure 1. v out -vs. v dac characteristics (v in = 5 v) figure 2. pwm mode v out settling t en indicates v out settles to 2% of the final value.
si9174 vishay siliconix www.vishay.com 8 document number: 71668 s-41148?rev. c, 14-jun-04 typical characteristics 0 40 80 120 160 200 0 100 200 300 400 500 600 75 80 85 90 95 100 0 100 200 300 400 500 600 load current (ma) efficiency (%) auto mode efficiency vs. load load decreasing load increasing 75 80 85 90 95 100 0 100 200 300 400 500 600 load current (ma) efficiency (%) psm psm vs. pwm efficiency 0 20 40 60 80 100 0 30 60 90 120 150 load current (ma) v in = 3.6 v v out = 1.9 v c out = 4.7 f v out ripple (mv p-p ) 70 75 80 85 90 95 100 0 100 200 300 400 500 600 load current (ma) efficiency (%) v in = 3.6 v v out = 3.0 v v out = 1.9 v load current (ma) dropout voltage (mv) auto mode efficiency vs. load direction dropout voltage vs. i load v out ripple pwm psm pwm v in = 3.6 v v in = 5.5 v v in = 2.6 v
si9174 vishay siliconix document number: 71668 s-41148?rev. c, 14-jun-04 www.vishay.com 9 typical switching waveforms (v in = 3.6 v, v out = 3.0 v) 200 ns/div v lx , 5 v/div inductor current 500 ma/div v out (ac-coupled) 10 mv/div pwm mode heavy-load switching w aveforms, i out = 600 ma, mode = high pwm mode medium-load switching w aveforms, i out = 300 ma, mode = high 200 ns/div v lx , 2 v/div inductor current 500 ma/div v out (ac-coupled) 10 mv/div 200 ns/div v lx , 5 v/div inductor current 200 ma/div v out (ac-coupled) 10 mv/div pwm mode light-load switching w aveforms, i out = 0 ma, mode = high 1.0 s/div v lx , 5 v/div inductor current 200 ma/div v out (ac-coupled) 10 mv/div psm mode light-load switching w aveforms, i out = 150 ma, mode = open 2.0 s/div v lx , 5 v/div inductor current 200 ma/div v out (ac-coupled) 100 mv/div psm mode light-load switching w aveforms, i out = 30 ma, mode = open
si9174 vishay siliconix www.vishay.com 10 document number: 71668 s-41148?rev. c, 14-jun-04 typical waveforms (v in = 3.6 v, v out = 1.9 v) 200 ns/div v lx , 5 v/div inductor current 500 ma/div v out (ac-coupled) 10 mv/div pwm mode heavy-load switching waveforms, i out = 600 ma, mode = high 200 ns/div v lx , 5 v/div inductor current 500 ma/div v out (ac-coupled) 10 mv/div pwm mode medium-load switching w aveforms, i out = 300 ma, mode = high 200 ns/div v lx , 5 v/div inductor current 200 ma/div v out (ac-coupled) 10 mv/div pwm mode light-load switching w aveforms, i out = 0 ma, mode = high 2.0 s/div v lx , 5 v/div inductor current 200 ma/div v out (ac-coupled) 100 mv/div psm mode light-load switching w aveforms, i out = 30 ma, mode = open 1.0 s/div v lx , 5 v/div inductor current 200 ma/div v out (ac-coupled) 100 mv/div psm mode light-load switching w aveforms, i out = 150 ma, mode = open
si9174 vishay siliconix document number: 71668 s-41148?rev. c, 14-jun-04 www.vishay.com 11 typical start-up and shutdown transient waveforms (v in = 3.6 v, v out = 1.9 v) 20 s/div v sd , 1 v/div v out , 500 mv/div start-up, r load = 4 20 s/div v in , v sd , 1 v/div start-up, v in = v sd = 3.6 v, r load = 4 200 s/div v sd , 1 v/div shutdown, r load = 4 20 s/div v sd 1 v/div enable switching, r load = 4 v out , 500 mv/div v out , 500 mv/div v out , 500 mv/div typical mode switch transient waveform v out (ac-coupled) 200 mv/div output t ransient at mode switch, i load = 30 ma 100 s/div mode pin 1 v/div
si9174 vishay siliconix www.vishay.com 12 document number: 71668 s-41148?rev. c, 14-jun-04 typical load transient waveforms (v in = 3.6 v, v out = 1.9 v) 10 s/div i load , 200 ma /div v out (ac-coupled) 50 v/div load transient, auto mode, i load = 30 to 500 ma, mode = low 10 s/div v out (ac-coupled) 50 mv/div i load , 200 ma /div load transient, pwm mode, i load = 30 to 500 ma, l = 2.2 h, mode= high 100 s/div v out (ac-coupled) 50 mv/div i load , 200 ma /div load transient (psm mode), i load = 30 to 150 ma, l = 2.2 h typical dac input response waveform v dac , 1 v/div output transient at mode switch, i load = 30 ma 100 s/div v out , 1 v/div
document number: 91000 www.vishay.com revision: 18-jul-08 1 disclaimer legal disclaimer notice vishay all product specifications and data are subject to change without notice. vishay intertechnology, inc., its affiliates, agents, and employees, and all persons acting on its or their behalf (collectively, ?vishay?), disclaim any and all liability fo r any errors, inaccuracies or incompleteness contained herein or in any other disclosure relating to any product. vishay disclaims any and all li ability arising out of the use or application of any product describ ed herein or of any information provided herein to the maximum extent permit ted by law. the product specifications do not expand or otherwise modify vishay?s terms and conditions of purcha se, including but not limited to the warranty expressed therein, which apply to these products. no license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document or by any conduct of vishay. the products shown herein are not designed for use in medi cal, life-saving, or life-sustaining applications unless otherwise expressly indicated. customers using or selling vishay products not expressly indicated for use in such applications do so entirely at their own risk and agree to fully indemnify vishay for any damages arising or resulting from such use or sale. please contact authorized vishay personnel to obtain written terms and conditions regarding products designed for such applications. product names and markings noted herein may be trademarks of their respective owners.

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