unisonic technologies co., ltd lr2125 linear integrated circuit www.unisonic.com.tw 1 of 8 copyright ? 2011 unisonic technologies co., ltd qw-r102-038.f 300m a selectable fixed/adjustable low dropout linear regulator ? description as a low dropout linear regulator, the utc lr2125 only needs low input voltage (2.8~6v) and can deliver current to 300ma for setting the output voltage. the utc lr2125 is an ideal for being used in such battery-powered equipments notebook, personal computer and cellular phone. its typical dropout voltage is 230mv at loading current 300ma. for setting the output voltage, the utc lr2125 has two output voltage operation modes: fixed m ode senses the out put voltage on v out , adj mode needs two resistors as a voltage divider. to protect itself against curr ent over-loads and over temperature, the lr2125 has current limit and thermal shutdown functions. ? features * operating voltage: 2.8~6v * low voltage dropout * output current guaranteed 300ma * for setting output voltage two modes ? fixed mode :fixed output voltage 1~5v ? adj mode: adjustable output voltage 0.8~5.5v * internal current limit protection * with soft-start * internal thermal protection * work stably with low esr ceramics capacitor ? ordering information ordering number package packing lead free halogen free lr2125l-xx-af5-r LR2125G-XX-AF5-R sot-25 tape reel
lr2125 linear integrated circuit unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r102-038.f ? marking information package voltage code marking sot-25 12 :1.2v 18 :1.8v 25 :2.5v ad :adj 3 2 1 sexx 5 4 voltage code g: halogen free l: lead free ? pin configuration ? pin description pin no pin name description 1 shdn control pin for shutdown logic high: enable logic low: shutdown 2 gnd ground 3 v in voltage supply 4 v out output pin 5 set when this pin is connected to ground, tu rns to fixed output voltage operation. when this pin is connected to an external resistor divider, turns to adjustable output voltage mode operation.
lr2125 linear integrated circuit unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r102-038.f ? block diagram
lr2125 linear integrated circuit unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r102-038.f ? absolute maximum rating (t a = 25 , unless otherwise specified) parameter symbol ratings unit v in supply voltage (v in to gnd) v in -0.3 ~ +6.5 v shdn input voltage ( shdn to gnd) shdn v -0.3 ~ +6.5 v power dissipation p d 380 mw junction temperature t j -40~ +125 storage temperature t stg -65 ~ +150 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 operation is not implied. ? recommended operating conditions parameter symbol ratings unit v in supply voltage v in 2.8 ~ 6 v output voltage v out 0.8 ~ 5.5 v v out output current i out 0 ~ 300 ma input capacitor c in 0.22 ~ 100 f output capacitor c out 1.5 ~ 33 f junction temperature t opr -40 ~ +85 ? electrical characteristics (v in = v out +1v (min v in =2.8v), i out =0~300ma, c in = 1 f, c out = 2.2 f, t a = 25 , unless otherwise specified) parameter symbol test conditions min typ max unit output voltage v out 0.8 5.5 v input voltage v in 2.8 6 v line regulation out in out v v v v out %/ v in , i out =10ma -0.06 +0.06 %/v load regulation out out out v i v v out %/ i out -0.2 +0.2 %/a output voltage accuracy fixed output voltage, i out =10ma -2 +2 % reference voltage v ref measured on set, v in =2.8v, i out =10ma 0.784 0.8 0.816 v quiescent current i q i out =10ma ~300ma 135 160 a dropout voltage v d v out = 2.5v, i out = 300ma 230 360 mv v out = 3.3v, i out = 300ma 170 300 mv power supply ripple rejection ratio psrr f = 10khz, i out = 300ma 45 db output voltage noise en f = 80hz ~ 100khz, i out = 300ma 160 v rms current limit i limit 400 500 650 ma shutdown threshold v ih 1.6 v v il 0.4 v shutdown supply current i off shdn = low, v in = 6v 0.1 1 a v out discharge mosfet r ds(on) shdn = low 60 ? thermal shutdown temperature t shdn 160 thermal shutdown hysteresis dt shdn 40 set input threshold for fixed/adjustable output voltage mode 100 mv set input bias current -100 100 na soft-start interval t ss 60 s
lr2125 linear integrated circuit unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r102-038.f ? application information input capacitor value larger than 1f, at least a 1f ceramic capacitor place be placed near the vin very closely purpose and advantage description to prevent the input rail from dropping, this capacitor can provide surge curr ent as while as the circuit?s stepping load transients. output capacitor value larger than 2.2f place be placed at the load and near the gnd pin very closely. purpose and advantage description mainly make sure the circuit?s operating stability. and t he large value capacitor also can reduce noise and improve transient response. additionally, it can affect power on issue. ) out v 0.1155 - (0.55 87 = out(max) c maximum output capacitor?s value (f) and t he output voltage (v)?s value?s relationship output capacitor,c out (f) maximum output capacitor?s changing over v out .
lr2125 linear integrated circuit unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r102-038.f ? typical application circuits for fixed output voltage mode for adjustable output voltage mode ) r2 r1 + (1 0.8 = v out
lr2125 linear integrated circuit unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r102-038.f ? typical characteristics output voltage,v out (v) input voltage,v in (v) output voltage vs. input voltage 0123456 0 0.5 1.0 1.5 2.0 2.5 3.0 i out =300ma i out =0ma 0 50 100 150 200 250 300 60 80 100 120 140 160 180 quiescent current, i q (a) output current, i out (ma) quiescent current vs. output current v in =5.5v v in =4.5v 123456 0 50 100 150 200 250 input voltage,v in (v) quiescent current,i q (a) quiescent current vs. input voltage i out =300ma i out =0ma 0 50 100 150 200 250 300 0 50 100 150 200 250 300 output current,i out (ma) dropout voltage,v drop (mv) dropout voltage vs. output current line transient ch1:v in ,1v/div,dc ch2:v out ,20mv/div,ac time:100s/div c in =1f,c out =2.2f, v out v in load transient v out i out v in =3.0v,c in =1f,c out =2.2f ch2:v out ,50mv/div,ac ch3:i out ,200ma/div,dc time:100s/div
lr2125 linear integrated circuit unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r102-038.f ? 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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