unisonic technologies co., ltd p1888 preliminary cmos ic www.unisonic.com.tw 1 of 4 copyright ? 2015 unisonic technologies co., ltd qw-r103-111.a pwm control 3a step-down converter ? description utc p1888 consists of 3a step-down switching regulator control which includes a reference voltage source, oscillation circuit, error amplifier, inte rnal pmos and etc with pwm. utc p1888 can provide low-ripple power, high efficiency, and excellent transient characterist ics and an enable function, an over current protect function and a short circuit protect function are built inside, so the operation frequency will be reduced from 300khz to 30khz when ocp or scp happens. and the pwm control circuit can vary the duty ratio linearly from 100 down to 0%. this converter also includes an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. also, to minimum external component count an internal compensation block is built in. utc p1888 can work as step-down switching regulators with the addition of an internal p-channel power mos, a coil, capacitors, and a diode connected externally. it provides such outstanding features: low current cons umption. it is also suitable for the operation via an ac adapter because this converter can accommodate an input voltage up to 23v. ? features * soft-start, current limit, enable function * thermal shutdown function * built-in internal sw p-channel mos * input voltage: 4v~23v. * output voltage: 1.23v~v cc . * duty ratio: 0% to 100% pwm control * oscillation frequency: 300khz typ. sop-8 ? ordering information ordering number package packing P1888G-S08-R sop-8 tape reel
p1888 preliminary cmos ic unisonic technologies co., ltd 2 of 4 www.unisonic.com.tw qw-r103-111.a ? marking ? pin configuration 1 nc v ss nc v cc output en nc fb 2 3 4 5 6 7 8 ? pin description pin no. pin name description 2 v cc ic power supply pin 3 output switch pin. connect external inductor/diode here. minimize trace area at this pin to reduce emi. 4 v ss gnd 5 fb feedback pin. 7 en power-off pin h: normal operation (step-do wn operation) l: step-down operation stopped (all circuits deactivated) ? block diagram v cc fb vss en output pwm-switched control circuit + - v en oscillation circuit reference voltage source with soft start thermal shutdown
p1888 preliminary cmos ic unisonic technologies co., ltd 3 of 4 www.unisonic.com.tw qw-r103-111.a ? absolute maximum rating parameter symbol ratings unit v cc pin voltage v cc v ss -0.3~v ss +25 v feedback pin voltage v fb v ss -0.3~v cc v en pin voltage v en v ss -0.3~v in +0.3 v switch pin voltage v output v ss -0.3~v in +0.3 v power dissipation p d internally limited mw operating ambient temperature t a -20~+85 c operating temperature t opr -20~+125 c storage temperature t stg -40~+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 134 c/w junction to case jc 22 c/w ? electrical characteristics (t a =25c, v in =12v, unless otherwise specified) parameter symbol conditions min. typ. max. unit input voltage v in 23 v feedback voltage v fb i out =0.1a 1.18 1.23 1.28 v feedback bias current i fb(bias) i out =0.1a 0.1 a switch current i sw 3.1 a standby current i stn-by v en =0v 10 a line regulation out out v v ? v in =5v~23v, i out =0.2a 1 % load regulation out out v v ? i out =0.1~3a 0.2 % oscillation frequency f osc measure waveform at sw pin 240 300 360 khz frequency of current limit or short circuit protect f osc1 measure waveform at sw pin 10 khz v sh evaluate oscillation at sw pin 0.79 v en pin input voltage v sl evaluate oscillation stop at sw pin 0.72 v i sh 20 a en pin input leakage current i sl -10 a soft-start time t ss 0.3 2 5 ms v in =5v, v fb =0v 110 150 m ? internal mosfet r ds(on) r ds(on) v in =12v, v fb =0v 70 100 m ? efficiency v in =12v, v out =5v, i out =3a 88 %
p1888 preliminary cmos ic unisonic technologies co., ltd 4 of 4 www.unisonic.com.tw qw-r103-111.a ? typical application circuit v in =12v, i max =3a v out 2.5v 3.3v 5v l 1 value 15h 18h 22h 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.
|
