unisonic technologies co., ltd uc3550 cmos ic www.unisonic.com.tw 1 of 10 copyright ? 2010 unisonic technologies co., ltd qw-r502-082,b pwm controlled pwm/pfm switchable step-up dc-dc controller ? description the utc uc3550 series is a compact, high efficiency, step-up dc/dc controllers includes an erro r amplifier, oscillator, pwm comparator, skip cycle comparator, voltage reference, soft-start, and high speed lower on-resistance driver for driving external power devices (nmos or npn) ,additionall y, a ce (chip enable) function that reduces power consumption during shut-down mode. that typically operated from a single-or dual-cell battery packs. it have a driver pin ,ext pin, for connecting to an external transistor(nmos or npn ) . a lower on-resistance external transistor can obtain larger output current. with only external components, this series allow a simple means to accommodate high output current applications. the utc uc3550 series goes automatically into skip switching cycles under light load condition to maintain high efficiency. ? features * input voltage range 0.9~8v * output voltage range 1.8~6v programmable in 0.1v with high accuracy 2.5% * high efficiency 88% (typ.) * low start-up voltage of 0.9v typical at i out = 1.0ma * oscillator frequency: 300khz.(20%) * chip enable pin with pull-up current source * high output current up to 1000ma (v in = 2.0v, v out =3.3v) sot-25 4 5 3 2 1 ? ordering information order number package packing UC3550G-XX-AF5-R sot-25 tape reel
uc3550 cmos ic unisonic technologies co., ltd 2 of 10 www.unisonic.com.tw qw-r502-082,b ? marking information package voltage code marking sot-25 33:3.3v 50:5.0v ? pin configuration ? pin description pin no pin name description 1 ce chip enable: the chip is enabled if a voltage equal to or greater than 1.0v or left floating is applied. the chip is disabled if a voltage less than 0.3v is applied. 2 out output voltage monitor, ic internal power supply 3 nc no connection 4 gnd ground 5 ext external transistor drive
uc3550 cmos ic unisonic technologies co., ltd 3 of 10 www.unisonic.com.tw qw-r502-082,b ? block diagram
uc3550 cmos ic unisonic technologies co., ltd 4 of 10 www.unisonic.com.tw qw-r502-082,b ? absolute maximum rating parameter symbol ratings unit supply voltage v out -0.3~8 v ext voltage v ext -0.3 ~ 8 v ext sink/source current i ext -150 ~ +150 ma ce input voltage range v ce -0.3 ~ 12.0 v ce input current range i ce -155 ~ 155 ma power dissipation (ta=25c) p d 500 mw junction temperature t j +150 c operating temperature t opr -40 ~ +85 c storage temperature t stg -55 ~ +150 c note: absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? thermal data parameter symbol ratings unit junction to ambient ja 250 c/w ? electrical characteristics (ta=25c, f osc 300khz, unless otherwise specified) uc3550-3.3v parameter symbol test conditions min typ max unit oscillator frequency f osc v out =v set 0.96 240 300 360 khz frequency temperature coefficient f ta=-40c ~ 85c 0.10 %/c maximum pwm duty cycle d max v out =v set 0.96 70 80 90 % minimum start-up voltage v start1 i out =0ma 800 900 mv minimum start-up voltage v start2 i out =1ma 900 1000 mv minimum start-up voltage temperature coefficient v start ta=-40c ~ 85c -1.6 mv/c minimum operation hold voltage v opr i out =0ma 600 700 mv soft-start time t ss v out =v set 60 250 ms ce (pin 1) ce input voltage : high state, device enabled v ceh 900 mv low state, device disabled v cel v out =v set 0.96 680 mv ce input current : high state, device enabled i ceh v out =v ce =5.0v -0.5 0 0.5 a low state, device disabled i cel v out =5.0v, v ce =0v 0 0.15 0.5 a ext (pin 5) ext ?h? r exth v ext =v out -0.4v 11 15 ? on resistance ext ?l? r extl v ext =0.4v 8 12 ? total device output voltage v out 3.218 3.3 3.383 v output voltage temperature coefficient v out ta=-40 ~ 85c 150 ppm/c operating current i dd v out =v ce =v set 0.96 103 160 a stand-by current i stn-by v out =v ce =v set +0.5v 15 38 a off-state current i off v out =5.0v, v ce =0v, ta=-40 ~ +85c 0.6 1.5 a efficiency i out = 200ma, v in = 2.0v 80 88 %
uc3550 cmos ic unisonic technologies co., ltd 5 of 10 www.unisonic.com.tw qw-r502-082,b ? electrical characteristics (cont.) uc3550-5.0v parameter symbol test conditions min typ max unit oscillator frequency f osc v out =v set 0.96 240 300 360 khz frequency temperature coefficient f ta=-40c ~ 85c 0.1 %/c maximum pwm duty cycle d max v out =v set 0.96 70 80 90 % minimum start-up voltage v start1 i out =0ma 800 900 mv minimum start-up voltage v start2 i out =1ma 900 1 v minimum start-up voltage temperature coefficient v start ta=-40c ~ 85c -1.6 mv/c minimum operation hold voltage v opr i out =0ma 600 700 mv soft-start time t ss v out =v set 60 200 ms ce (pin 1) ce input voltage : high state, device enabled v ceh 900 mv low state, device disabled v cel v out =v set 0.96 680 mv ce input current : high state, device enabled i ceh v out =v ce =5.0v -0.5 0 0.5 a low state, device disabled i cel v out =5.0v, v ce =0v 0 0.15 0.5 a ext (pin 5) ext ?h? r exth v ext =v out -0.4v 6 10 ? on resistance ext ?l? r extl v ext =0.4v 6 10 ? total device output voltage v out 4.875 5 5.125 v output voltage temperature coefficient v out ta=-40 ~ 85c 150 ppm/c operating current i dd v out =v ce =v set 0.96 136 220 a stand-by current i stn-by v out =v ce =v set +0.5v 15 38 a off-state current i off v out =5.0v, v ce =0v, ta=-40 ~ +85c 0.6 1.5 a efficiency i out = 200ma, v in = 3.0v 80 88 %
uc3550 cmos ic unisonic technologies co., ltd 6 of 10 www.unisonic.com.tw qw-r502-082,b ? typical step-up converter application ce out nc ext gnd v out v in 1 2 34 5 utc uc3550 10uf 220uf step-up converter using external mosfet 10uh ce out nc ext gnd v out v in 1 2 34 5 utc uc3550 cb 3000p rb 560 10uf 220uf step-up converter using external npn 10uh 0.1 0.1 recommended components nmos t r xp161a0390pr/ (torex) or ntgs3446t1(on semi) l 10uh(sunida cd54 fosc 300khz) sd ma737, or mbrm110l c in 10v 10uf (tantalum) c l 16v220uf (tantalum) npn t r type t r 2sd1628(sanyo) mmjt9410 r b 500 1000 ? (adjust according to load and tr. h fe levels) c b 3000p(ceramic type)
uc3550 cmos ic unisonic technologies co., ltd 7 of 10 www.unisonic.com.tw qw-r502-082,b ? external component selection inductor selection an inductor value of 10uh performs well in most applicat ion. the uc3550 series also work with inductors in the 4.7uh to 12uh range. an inductor with higher peak in ductor current tends a higher output voltage ripple(i peak x output filter capacitor esr). the inductor?s dc resistance significantly affects efficiency. output capacitor selection the output ripple voltage(i peak x output filter capac itor esr)is the product of the peak inductor current and the output capacitor equivalent series resistance (esr). best performances are obtained with good high frequency characteristics capacitors and low esr. the best compromi se for the value of the ou tput capacitance is 220f tantalum capacitor. the output capacitor as close as possible to the device pins. input capacitor selection the input capacitor is required to compensate, if pr esent, the series impedance between the supply voltage source and the input voltage of the a pplication. a value of 10 f is enough to guarantee stability for distances less than 2". in any case we suggest to connect both capacitors , the input capacitor as close as possible to the device pins. diode selection the schottky diode with an high switching speed and a very low forward voltage (vf) is needed. higher vf may cause lost power as heat in the diode, with a decrease of the efficiency. mor eover, since the output voltage pin is also used as the device supply voltag e, the start-up voltage (see re lated plots) is strictly due to the diode forward voltage at the rated forward current. external component selection an enhancement n-channel mosfet or a bipolar npn transis tor can be used as the external switch transistor. since enhancement n-channel mosfet is a voltage driven device, it is a more e fficient switch than a bjt transistor. however, he mosfet requires a higher voltage to turn on as compared with bjt transistor for enhancement n-channel mosfet ( it is especially importance for r ds ( on ),typically<0.1 ? , threshold voltage, v gs ( th ) must be uc3550 cmos ic unisonic technologies co., ltd 8 of 10 www.unisonic.com.tw qw-r502-082,b ? typical characteristics 1 0.1 2 34 5 1 10 0.01 1 1 2 34 5 10 100 0.01 0.1 no load input current, i in (ma) no load input current vs. input volt age (using mosfet) v out =5.0v v out =3.0v input voltage, v in (v) no load input current, i in (ma) v out =5.0v, r b =560 ? v out =3.0v, r b =560 ? input voltage, v in (v) no load input current vs. input voltage (using bjt) 6 output voltage, v out (v) maximum duty cycle, d max (%)
uc3550 cmos ic unisonic technologies co., ltd 9 of 10 www.unisonic.com.tw qw-r502-082,b ? typical characteristics(cont.) 0. 0 1 20 40 60 0. 1 0 110 100 1000 80 100 efficiency vs output current (5.0v) 0 0.4 0.8 1.2 20 40 60 80 100 1.6 2.0 0.0 v in =3.0v v in =2.0v v in =0.9v efficiency (%) output current, i out (ma) startup/hold voltage vs output current (using mosfet) output current (3.3v) v start v nold output current, i c (ma) startup/hold voltage, v start /v hold (v) -50 5 10 15 - 25 0 25 50 100 20 25 75 0 0 120 140 160 200 400 600 800 180 200 1000 100 80 60 40 20 0 ext on-resistance vs temperature on-resistance, ( ? ) v out =5.0v0.96 v ext =v out -0.4v open-loop test v out =5.0v0.96 v ext =0.4v open-loop test temperature output current, i out (ma) v in =2.0v v in =1.5v v in =3.0v v in =4.5v ripple voltage, v ripple (mv) ripple voltage vs output current oscilator frequency, f osc (khz) oscilator frequency, f osc (khz)
uc3550 cmos ic unisonic technologies co., ltd 10 of 10 www.unisonic.com.tw qw-r502-082,b ? typical characteristics(cont.) utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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