unisonic technologies co., ltd p1886 linear integrated circuit www.unisonic.com.tw 1 of 8 copyright ? 2009 unisonic technologies co., ltd qw-r103-042.c pwm control 3a step-down converter ? description utc p1886 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 p1886 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 c ount an internal compensation block is built in. utc p1886 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 c onsumption. 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 to 23v. * output voltage: 0.8v to v cc . * duty ratio: 0% to 100% pwm control * oscillation frequency: 300khz typ. sop-8 ? ordering information ordering number lead free halogen free package packing p1886l-s08-r P1886G-S08-R sop-8 tape reel
p1886 linear integrated circuit unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r103-042.c ? pin connections 1 nc v ss nc v cc output en nc fb 2 3 4 5 6 7 8 ? pin descriptions pin no 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)
p1886 linear integrated circuit unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r103-042.c ? block diagram v cc fb vss en output pwm-switched control circuit + - v en oscillation circuit reference voltage source with soft start thermal shutdown
p1886 linear integrated circuit unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r103-042.c ? absolute maximum ratings parameter symbol rating 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 min typ max 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 4 23 v feedback voltage v fb i out =0.1a 0.784 0.8 0.816 v feedback bias current i fb(bias) i out =0.1a 0.1 0.5 a switch current i sw 3.5 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 2 % load regulation out out v v i out =0.1~3a 0.2 0.5 % 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 %
p1886 linear integrated circuit unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r103-042.c ? function description pwm control the utc p1886 consists of dc/dc converters which employ a pwm system. in this dc/dc converter, the pulse width varies in a range from 0 to 100% which is according to the load current. cause the switching frequency remains constant the ripple voltage which produced by t he switching can be removed easily through a filter. therefore, these converters provi de a low-ripple power over broad ranges of input voltage and load current.
p1886 linear integrated circuit unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r103-042.c test circuits + - ? typical application circuit v in =12v, i max =3a v out 2.5v 3.3v 5v l 1 value 15h 18h 22h
p1886 linear integrated circuit unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r103-042.c ? typical characteristics input voltage vs. frequency 270 275 280 285 290 295 300 305 310 315 320 0 510 15 20 25 input voltage,v in (v) oscillation frequency,fosc (khz) input voltage vs. feedback voltage 0.74 0 51015 20 25 feedback voltage, fb (v) 0.75 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 v out =5v i out =0.2a input voltage,v in (v) v out =5v i out =0.2a line regulation 4.70 0 510 15 20 25 input voltage,v in (v) output voltage,v out (v) 4.75 4.80 4.85 4.90 4.95 5.00 load regulation 4.89 0.0 1.0 2.0 ouput current,i out (a) output voltage,v out (v) 4.90 4.91 4.92 4.93 4.94 4.95 4.96 4.97 4.98 4.99 v out =5v i out =0.2a 0.5 1.5 v in =12v 2.5 3.0 output current vs. efficiency 0 0.0 1.0 2.0 0.5 efficiency (%) 10 20 30 40 50 60 70 80 90 100 output current,i out (a) v out =5.0v v out =3.3v 1.5 3.0 2.5
p1886 linear integrated circuit unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r103-042.c 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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