unisonic technologies co., ltd uc3655 preliminary cmos ic www.unisonic.com.tw 1 of 9 copyright ? 2011 unisonic technologies co., ltd qw-r502-280.c 500ma synchronous step-down dc/dc converters ? description the utc uc3655 is a synchronous-rectification type dc/dc converters with a built-in 0.6 ? p-channel driver transistor and 0.7 ? n-channel switching transistor, which designed to allow the use of ceramic capacitors. using only a coil and two capacitors connected externally, the uc3655 enable a high efficiency, stable power supply with an output current of 500ma to be configured. its operating voltage is 2.0v and the output voltage is programmable in a range from 0.9v to 4.0v in increments of 0.1v (accuracy: 2.0%) internally. the oscillation frequency is 1.2mhz. for operation mode, it is pwm control in the utc uc3655 , the utc uc3655 series is automatic pwm/pfm swit ching control, allowing fast response, low ripple and high efficiency over the full range of load. internal soft start and current control functions are built in it. all circuits are shutdown to reduce current consumption to as low as 1.0 a or less during standby mode. with the built-in under voltage lock out (u.v.l.o.) function, when input voltage bec omes 1.4v or lower the internal p channel driver transistor is forced off. ? features * very high efficiency 92% * low ripple rejection voltage 10mv * output current 500ma @v in =3.0v, v out =1.8v * oscillation frequency is 1.2mhz * with pwm / pfm automa tic switching control * maximum duty ratio is 100% * ceramic capaci tor available ? ordering information ordering number package packing lead free halogen free UC3655L-XX-AF5-R uc3655g-xx-af5-r sot-25 tape reel
uc3655 preliminary cmos ic unisonic technologies co., ltd 2 of 9 www.unisonic.com.tw qw-r502-280.c ? marking package voltage code marking sot-25 12:1.2v 28:2.8v 33:3.3v 38:3.8v 3 2 1 5 4 uhxx g voltage code g: halogen free l: lead free ? pin description pin no pin name description 1 v in power input voltage 2 v ss ground 3 ce / mode switch pin for chip enable mode 4 v out output voltage sense pin 5 lx output of switching
uc3655 preliminary cmos ic unisonic technologies co., ltd 3 of 9 www.unisonic.com.tw qw-r502-280.c ? block diagram
uc3655 preliminary cmos ic unisonic technologies co., ltd 4 of 9 www.unisonic.com.tw qw-r502-280.c ? absolute maximum rating (t a =25c) parameter symbol ratings unit v in pin voltage v in - 0.3 ~ 6.5 v input/output pins lx v lx - 0.3 ~ v in + 0.3 v v out v out -0.3 ~ 6.5 ce/mode v ce - 0.3 ~ v in + 0.3 lx pin current i lx 1000 ma power dissipation p d 250 mw operating temperature t opr - 40 ~ 85 c storage temperature range t stg - 55 ~ 125 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. ? electrical characteristics (f osc =1.2mhz, t a =25c) uc3655-12 (v in =3.6v, v out =1.2v) parameter symbol test conditions min typ max unit operating voltage range v in 2.0 6.0 v output voltage v out ce=v in , i out =30ma 1.176 1.200 1.224 v u.v.l.o. voltage v uvlo ce=v in , v out =0v, lx=l 1.0 1.40 1.78 v output voltage temperature characteristics t opr i out =30ma, -40c t opr 85c 100 ppm/c maximum output current i out ( ma x ) v in =4.5v 500 ma supply current i dd v in =ce=5.0v, v out =v out *1.1 70 115 a stand-by current i stn-by v in =5.0v, ce=0v, v out =v out *1.1 0 1.0 a pfm switch current i pfm ce=v in , i out =1ma 100 140 180 ma current limit i lim v in =ce=5.0v, v out =0v 600 700 ma efficiency (note 1) ce=v in =4.5v, i out =100ma 90 % oscillator oscillation frequency f osc i out =100ma 1020 1200 1380 khz maximum duty ratio d max ce=v in , v out =0v 100 % minimum duty ratio d min ce=v out =v in 0 % soft-start time t ss i out =1ma 0.5 1.0 3.0 ms latch time t lat v in =ce=5.0v (note 3) 1 20 ms ce (pin 3) ce "h" voltage v ceh 0.9 v in v ce "l" voltage v cel v ss 0.3 v ce "h" current i ceh v in =ce=5.5v, v out =0v -0.1 0.1 a ce "l" current i cel v in =5.5v, ce=0v, v out =0v -0.1 0.1 a lx (pin 5) lx sw "h" on resistance r lxh ce=0.5v in , v out =0v, i l x =100ma 0.6 ? lx sw "l" on resistance r lxl ce=0.5v in , i l x =100ma 0.7 ? lx sw "h" leak current (note 2) i leakh v in =v out =5.0v, ce=0v, lx=0v 0.01 1.0 a lx sw "l" leak current i leakl v in =v out =5.0v, ce=0v, lx=5.0v 0.01 1.0 a
uc3655 preliminary cmos ic unisonic technologies co., ltd 5 of 9 www.unisonic.com.tw qw-r502-280.c ? electrical characteristics(cont.) uc3655-28 (v in =3.6v, v out =2.8v) parameter symbol test conditions min typ max unit operating voltage range v in 2.0 6.0 v output voltage v out ce=v in , i out =30ma 2.744 2.8 2.856 v u.v.l.o. voltage v uvlo ce=v in , v out =0v, lx=l 1.0 1.40 1.78 v output voltage temperature characteristics t opr i out =30ma, -40c t opr 85c 100 ppm/c maximum output current i out ( ma x ) v in =4.5v 500 ma supply current i dd v in =ce=5.0v, v out =v out *1.1 75 120 a stand-by current i stn-by v in =5.0v, ce=0v, v out =v out *1.1 0 1.0 a pfm switch current i pfm ce=v in , i out =1ma 100 140 180 ma current limit i lim v in =ce=5.0v, v out =0v 600 700 ma efficiency (note 1) ce=v in =4.5v, i out =100ma 92 % oscillator oscillation frequency f osc i out =100ma 1020 1200 1380 khz maximum duty ratio d max ce=v in , v out =0v 100 % minimum duty ratio d min ce=v out =v in 0 % soft-start time t ss i out =1ma 0.5 1.0 3.0 ms latch time t lat v in =ce=5.0v (note 3) 1 20 ms ce (pin 3) ce "h" voltage v ceh 0.9 v in v ce "l" voltage v cel v ss 0.3 v ce "h" current i ceh v in =ce=5.5v, v out =0v -0.1 0.1 a ce "l" current i cel v in =5.5v, ce=0v, v out =0v -0.1 0.1 a lx (pin 5) lx sw "h" on resistance r lxh ce=0.5v in , v out =0v, i l x =100ma 0.5 ? lx sw "l" on resistance r lxl ce=0.5v in , i l x =100ma 0.6 ? lx sw "h" leak current i leakh v in =v out =5.0v, ce=0v, lx=0v (note 2) 0.01 1.0 a lx sw "l" leak current i leakl v in =v out =5.0v, ce=0v, lx=5.0v 0.01 1.0 a uc3655-33 (v in =5.0v, v out =3.3v) parameter symbol test conditions min typ max unit operating voltage range v in 2.0 6.0 v output voltage v out ce=v in , i out =30ma 3.234 3.300 3.366 v u.v.l.o. voltage v uvlo ce=v in , v out =0v, lx=l 1.0 1.40 1.78 v output voltage temperature characteristics t opr i out =30ma, -40 t opr 85 100 ppm/c maximum output current i out ( ma x ) v in =4.5v 500 ma supply current i dd v in =ce=5.0v, v out =v out *1.1 75 120 a stand-by current i stn-by v in =5.0v, ce=0v, v out =v out *1.1 0 1.0 a pfm switch current i pfm ce=v in , i out =1ma 100 140 180 ma current limit i lim v in =ce=5.0v, v out =0v 600 700 ma efficiency (note 1) ce=v in =4.5v, i out =100ma 92 % oscillator oscillation frequency f osc i out =100ma 1020 1200 1380 khz maximum duty ratio d max ce=v in , v out =0v 100 % minimum duty ratio d min ce=v out =v in 0 % soft-start time t ss i out =1ma 0.5 1.0 3.0 ms latch time t lat v in =ce=5.0v (note 3) 1 20 ms
uc3655 preliminary cmos ic unisonic technologies co., ltd 6 of 9 www.unisonic.com.tw qw-r502-280.c ? electrical characteristics(cont.) parameter symbol test conditions min typ max unit ce (pin 3) ce "h" voltage v ceh 0.9 v in v ce "l" voltage v cel v ss 0.3 v ce "h" current i ceh v in =ce=5.5v, v out =0v -0.1 0.1 a ce "l" current i cel v in =5.5v, ce=0v, v out =0v -0.1 0.1 a lx (pin 5) lx sw "h" on resistance r lxh ce=0.50v in , v out =0v, i l x =100ma 0.5 ? lx sw "l" on resistance r lxl ce=0.5v in , i l x =100ma 0.6 ? lx sw "h" leak current (note 2) i leakh v in =v out =5.0v, ce=0v, lx=0v 0.01 1.0 a lx sw "l" leak current i leakl v in =v out =5.0v, ce=0v, lx=5.0v 0.01 1.0 a uc3655-38 (v in =5.0v, v out =3.8v) parameter symbol test conditions min typ max unit operating voltage range v in 2.0 6.0 v output voltage v out ce=v in , i out =30ma 3.724 3.800 3.876 v u.v.l.o. voltage v uvlo ce=v in , v out =0v, lx=l 1.0 1.40 1.78 v output voltage temperature characteristics t opr i out =30ma, -40 t opr 85 100 ppm/c maximum output current i out ( ma x ) v in =4.5v 500 ma supply current i dd v in =ce=5.0v, v out =v out *1.1 75 120 a stand-by current i stn-by v in =5.0v, ce=0v, v out =v out *1.1 0 1.0 a pfm switch current i pfm ce=v in , i out =1ma 100 140 180 ma current limit i lim v in =ce=5.0v, v out =0v 600 700 ma efficiency (note 1) ce=v in =4.5v, i out =100ma 92 % oscillator oscillation frequency f osc i out =100ma 1020 1200 1380 khz maximum duty ratio d max ce=v in , v out =0v 100 % minimum duty ratio d min ce=v out =v in 0 % soft-start time t ss i out =1ma 0.5 1.0 3.0 ms latch time t lat v in =ce=5.0v (note 3) 1 20 ms ce (pin 3) ce "h" voltage v ceh 0.9 v in v ce "l" voltage v cel v ss 0.3 v ce "h" current i ceh v in =ce=5.5v, v out =0v -0.1 0.1 a ce "l" current i cel v in =5.5v, ce=0v, v out =0v -0.1 0.1 a lx (pin 5) lx sw "h" on resistance r lxh ce=0.5v in , v out =0v, i l x =100ma 0.5 ? lx sw "l" on resistance r lxl ce=0.5v in , i l x =100ma 0.6 ? lx sw "h" leak current (note 2) i leakh v in =v out =5.0v, ce=0v, lx=0v 0.01 1.0 a lx sw "l" leak current i leakl v in =v out =5.0v, ce=0v, lx=5.0v 0.01 1.0 a note: 1. = [(v out *i out )/(v in *i in )]*100 note: 2. when temperature is high, a current of approximately 20 a (maximum) may leak. note: 3. time until it short-circ uits dcout with gnd through 1 ? of resistance from a state of operation and is set to dcout=0v from current lim it pulse generating.
uc3655 preliminary cmos ic unisonic technologies co., ltd 7 of 9 www.unisonic.com.tw qw-r502-280.c ? operational explanation ce / mode pin function when a low level signal is input to the ce/mode pin the operation of the uc3655 series will enter into the shut down mode. in this mode, the cu rrent consumption occurs on ly in the detector and is 0 a (typ.), with a state of high impedance at the lx pin and vout pin. by inputting a hi gh level signal to the ce/mode pin the ic starts its operation. the input of the ce/mode pin is a cmos input and its sink current is 0 a (typ.). uc3655 series - examples of how to use ce/mode pin v dd r1 ce/mode sw_ce v in sw_ce status on stand-by off operation sw_ce status on stand-by off operation ? functions ce/mode voltage level operation h level v in -0.3v Q h level Q v in synchronous pwm/pfm automatic switching control m level 0.9v Q m level Q v in -1.0v l level 0v Q l level Q 0.3v stand-by
uc3655 preliminary cmos ic unisonic technologies co., ltd 8 of 9 www.unisonic.com.tw qw-r502-280.c ? test circuit c i 4.7f (ceramic) c l 10f (ceramic) l 3.3h
uc3655 preliminary cmos ic unisonic technologies co., ltd 9 of 9 www.unisonic.com.tw qw-r502-280.c ? typical application circuit v in ce/ mode v ss v out l x c i l c l v in ce/mode v out (400ma) 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. c i 4.7f (ceramic) c l 10f (ceramic) l 3.3h
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