unisonic technologies co., ltd LD1985 linear integrated circuit www.unisonic.com.tw 1 of 9 copyright ? 2013 unisonic technologies co., ltd qw-r102-021.h very low drop and low noise voltage regulator low esr cap. compatible, with inhibit function ? description the utc LD1985 is a 150ma fixed output voltage regulator. the ultra low drop voltage and the lo w quiescent current make them particularly suitable for low noise, low power applications, and in battery powered systems. in sleep mode qu iescent current is less than 1 a when inhibit pin is pulled low. s hutdown logic control function is available on pin 3 (ttl compatible). this means that when the device is used as local regulator, it is possi ble to put a part of the board in standby, decreasing the total power consumption. an external capacitor, c byp =10nf, connected between bypass pin and gnd reduce the noise to 30 vrms. typical application is in cellula r phone, palmtop laptop computer, personal digital assistant (pda), personal stereo, camcorder and camera. ? features * very low dropout voltage (280mv at 150ma and 7mv at 1ma load) * very low quiescent current * output current up to 150ma * logic controlled electronic shutdown * output voltage of 1. 5, 1.8, 2.5, 2.8, 2. 85, 3, 3.1, 3.2, 3. 3, 3.5, 3.6, 3.8, 4, 4.7, 5v * internal current and thermal limit * low output noise voltage 30 vrms ? ordering information ordering number package packing lead free halogen free LD1985l-xx-af5-r LD1985g-xx-af5-r sot-25 tape reel note: xx: output voltage, re fer to marking information.
LD1985 linear integrated circuit unisonic technologies co., ltd 2 of 9 www.unisonic.com.tw qw-r102-021.h ? marking information package voltage code marking sot-25 15:1.5v 18:1.8v 25:2.5v 28:2.8v 2j:2.85v 30:3.0v 31:3.1v 32:3.2v 33:3.3v 35:3.5v 36:3.6v 38:3.8v 40:4.0v 47:4.7v 50:5.0v ? pin configuration ? pin description pin no. pin name description 1 v in input port 2 gnd ground pin 3 inhibit control switches on/off. inhibit is not inte rnally pulled-up; it cannot be left floating. disable the device when connected to gn d or to a positive voltage less than 0.18v 4 bypass bypass pin: capacitor to be connected to g nd in order to improve the thermal noise performances. 5 v out output port ? block diagram v out driver error amplifier current limit reference voltage start-up shutdown term. protec. gnd bypass inhibit v in
LD1985 linear integrated circuit unisonic technologies co., ltd 3 of 9 www.unisonic.com.tw qw-r102-021.h ? absolute maximum ratings (t a =25c) parameter symbol ratings unit dc input voltage v in 7 v inhibit input voltage v inh 7 v output current i out internally limited power dissipation p d internally limited operating junction temperature t opr -40 ~ +85 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 an d functional device operat ion is not implied. ? thermal data parameter symbol ratings unit junction to case jc 81 c/w ? electrical charactristics (t j =25c, v in =v out +1v, i out =1ma, v shdn =2v, c i =1 f, c o =1 f, unless otherwise specified) parameter symbol test conditions min typ max unit operating input voltage v i ( opr ) 2.5 7 v output voltage v out v in =2.5v 1.470 1.5 1.530 v i out =1 ~ 150ma 1.455 1.545 v v in =2.8v 1.764 1.8 1.836 v i out =1 ~ 150ma 1.746 1.854 v v in =3.5v 2.450 2.5 2.550 v i out =1 ~ 150ma 2.425 2.575 v v in =3.8v 2.744 2.8 2.856 v i out =1 ~ 150ma 2.716 2.884 v v in =3.85v 2.793 2.85 2.907 v i out =1 ~ 150ma 2.764 2.936 v v in =4.0v 2.940 3.0 3.060 v i out =1 ~ 150ma 2.910 3.090 v v in =4.1v 3.038 3.1 3.162 v i out =1 ~ 150ma 3.007 3.193 v v in =4.2v 3.136 3.2 3.264 v i out =1 ~ 150ma 3.104 3.296 v v in =4.3v 3.234 3.3 3.366 v i out =1 ~ 150ma 3.201 3.399 v v in =4.5v 3.430 3.5 3.570 v i out =1 ~ 150ma 3.395 3.605 v v in =4.6v 3.528 3.6 3.672 v i out =1 ~ 150ma 3.492 3.708 v v in =4.8v 3.724 3.8 3.876 v i out =1 ~ 150ma 3.686 3.914 v v in =5.0v 3.920 4 4.080 v i out =1 ~ 150ma 3.880 4.120 v v in =5.7v 4.606 4.7 4.794 v i out =1 ~ 150ma 4.559 4.841 v v in =6.0v 4.900 5 5.100 v i out =1 ~ 150ma 4.850 5.150 v
LD1985 linear integrated circuit unisonic technologies co., ltd 4 of 9 www.unisonic.com.tw qw-r102-021.h ? electrical charactristics(cont.) parameter symbol test conditions min typ max unit short circuit current i sc r l =0 600 ma line regulation v out v in = v out +1v ~ 7v, i out =1ma 30 mv dropout voltage v d i out =0 1 3 mv i out =1ma 7 10 mv i out =10ma 40 60 mv i out =50ma 120 150 mv i out =150ma 280 350 mv quiescent current i q i out =0 80 100 a i out =1ma 100 150 a i out =10ma 280 330 a i out =50ma 1050 1300 a i out =150ma 2900 3300 a off mode v inh <0.18v 1.5 a supply voltage rejection svr c byp =0.01 f, co=10 f, f=1khz 45 db control input logic low v il t j =-20 ~ 125c 0.15 v control input logic high v ih t j =-20 ~ 125c 2 v control input current i inh t j =-20 ~ 125c, v shdn =5v 5 15 a t j =-20 ~ 125c, v shdn =0v 0 -1 a output noise voltage en b=300hz ~ 50khz c byp =0.01 f, co=10 f 30 v
LD1985 linear integrated circuit unisonic technologies co., ltd 5 of 9 www.unisonic.com.tw qw-r102-021.h ? reverse current test circuit
LD1985 linear integrated circuit unisonic technologies co., ltd 6 of 9 www.unisonic.com.tw qw-r102-021.h ? application information external capacitors like any low-dropout regulator, the utc LD1985 requires external capacitors for regulator stability. this capacitor must be selected to meet t he requirements of minimum capacitance an d equivalent series resistance. we suggest soldering input and outputting capacitors as close as possible to the relative pins. input capacitor an input capacitor whose value is 1 f is required with the utc LD1985 (amount of capacitance can be increased without limit). this capacitor must be located a distance of not mo re than 0.5" from the input pin of the device and returned to a clean analog ground. any good qua lity ceramic, tantalum or f ilm capacitors can be used for this capacitor. output capacitor the utc LD1985 is designed specifically to work with ceramic output capacitors. it may also be possible to use tantalum capacitors, but these are not as attractive for reasons of size and cost. by the way, the output capacitor must meet both the requirement for mini mum amount of capacitance and e.s.r. ( equivalent series resistance) value. due to the different loop gain, the stability improves fo r higher output versions and so the suggested minimum output capacitor value, if low e.s.r. ceramic type is used, is 1 f for output voltages equal or major than 3.8v, 2.2 f for v out going from 1.8 ~ 3.3v, and 3.3 f for the other versions. however, if an output capacitor lower than the suggested one is used, it's possible to make stable the regulator adding a resistor in series to the capacitor. important: the output capacitor must maintain it s esr in the stable region over the full operating temperature to assure stability. also, capacitor tolerance and variation with temp erature must be considered to assure the minimum amount of capacitance is provided at all times. this capacitor should be located not mo re than 0.5" from the output pin of the device and returned to a clean analog ground. inhibit input operation the inhibit pin can be used to turn off the regulator when pulled low, so drastically reducing the current consumption down to less than 1 a. when the inhibit feature is not used, this pin must be tied to v in to keep the regulator output on at all times. to a ssure proper operation, the signal source used to drive the inhibit pin must be able to swing above and below the specified thresholds lis ted in the electrical char acteristics section under v ih v il . any slew rate can be used to drive the inhibit. reverse current the power transistor used in the utc LD1985 has not an inherent diode conn ected between the regulator input and output. if the output is forced above the input, no current will flow from the output to the input across the series pass transistor. when a v rev voltage is applied on the output, the reve rse current measured flows to the gnd across the two feedback resistors. th is current typical value is 160 a. r1 and r2 resistors are implanted type; typical values are, respectively, 42.6 k ? and 51.150 k ? .
LD1985 linear integrated circuit unisonic technologies co., ltd 7 of 9 www.unisonic.com.tw qw-r102-021.h ? typical characteristics (t j =25c, c in =1 f, c out =2.2 f, c byp =100nf) 2.58 -25 -50 25 0 2.46 2.50 2.56 75 2.54 2.48 2.44 50 100 output voltage vs temperature 2.52 tc ( ) 2.42 2.40 v out (v) v in =3.5v i out =1ma 2500 25 0 75 50 500 2000 125 1500 100 150 quiescent current vs load current 1000 i out (ma) 0 i q ( a) v out =2.5v c by =10nf 125 2.60 175 -25 -50 25 0 0.2 0.3 75 0.1 50 100 dropout voltage vs temperature 0 v d (v) v out =2.5v c by =10nf i out =150ma i out =50ma i out =10ma i out =1ma -25 -50 25 0 2.0 3.5 75 1.5 50 100 quiescent current vs temperature 0 i q (ma) v out =2.5v c by =10nf i out =150ma 3.0 2.5 1.0 0.5 t c ( ) t c ( ) 125 25 0 75 50 100 150 250 125 200 100 150 dropout voltage vs output current i out (ma) 50 0 v d (mv) v out =2.5v -25 -50 25 0 60 90 75 50 50 100 supply voltage rejection vs temperature 20 svr (db) c out =10 f 80 70 40 30 c out =1 f f osc =1khz v in =3.5 ~ 6.5v i out =10ma t c ( ) 125 175 0.4 125 3000
LD1985 linear integrated circuit unisonic technologies co., ltd 8 of 9 www.unisonic.com.tw qw-r102-021.h ? typical characteristics(cont.) 80 25 0 75 50 60 125 40 100 150 supply voltage rejection vs output current 20 i out (ma) 0 svr (db) v in =3.5 ~ 6.5v c out =10 f f osc =1khz 70 60 40 supply voltage rejection vs frequency 20 f (khz) 0 svr (db) 50 30 10 10 1 10 2 10 3 10 4 v in =3.5 ~ 6.5v i out =10ma v out =2.5v c out =1 f 80 25 0 75 50 60 125 40 100 150 supply voltage rejection vs output current 20 i out (ma) 0 v in =3.5 ~ 6.5v c out =1 f f osc =1khz line transient v in v out v out =2.5v, i out =50ma, no c in , c out =4.7 f, t r =t f =20ns ch1 500mv 20.0mv ch2 m 10.0 s ch1 3.96v ch2 1 1 100 175 svr (db) 100 175 80 10 5 line transient v in v out v out =2.5v, i out =50ma, no c in , c out =4.7 f, t r =t f =1 s 500mv 20.0mv ch2 m 10.0 s ch1 3.96v 1 ch1 ch2 2 f (khz) 70 60 40 supply voltage rejection vs frequency 20 0 svr (db) 50 30 10 10 1 10 2 10 3 10 4 v in =2.8 ~ 5.8v i out =10ma v out =1.8v c out =10 f 10 5 tek run:5.00ms/s tek run:5.00ms/s
LD1985 linear integrated circuit unisonic technologies co., ltd 9 of 9 www.unisonic.com.tw qw-r102-021.h ? 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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