unisonic technologies co., ltd lxxld15 preliminary cmos ic www.unisonic.com.tw 1 of 8 copyright ? 2011 unisonic technologies co., ltd qw-r502-638.a 0.8v reference ultra low dropout linear regulator ? description the utc lxxld15 is a typical ldo with the feature of very low dropout voltage as low as 0.2v at output current 1.5a. for normal operation, two supply voltages are necessary. one called control voltage from other equipment can shutdown the output voltage and it should pu ll and hold the voltage of en pin less than 0.3v. another one is the main supply voltage whose purpose is for main power conversion to keep the power dissipation low and to make the dropout voltage lower. internally, in the utc lxxld15 , there?re many functions which can be seen in the block figure to prevent the ic from being damaged. internal power-on-reset (por) circuit can control the two supply voltages to prevent fault operations of the circuit. and the thermal shutdown circuit is able to protect the device from over thermal operati on and a current limit function will keep the device work safely under current over-load. the utc lxxld15 can be used as an ideal to provide well supply voltage in the applicat ions, such as front-side-bus termination on motherboard, nb applications, front side bus v tt (1.2v/1.5a) and note book pc applications. hsop-8 ? features * low dropout v d =0.2v (typ.) @ i out =1.5a * low esr output capacitor * v ref =0.8v * 1.5% over line, load and temperature output accuracy * fast transient response * output voltage adjustable through external resistors * por (power-on-reset) controlling v cntl and v in ? features * with internal soft-start * internal current limit protection * internal under voltage protection * hysteretic thermal shutdown * with power-ok output (with a delay time) * for standby or suspend mode: shutdown ? ordering information ordering number lead free halogen free package packing lxxld15l-sh2-r LXXLD15G-SH2-R hsop-8 tape reel note: xx: output voltage, re fer to marking information.
lxxld15 preliminary cmos ic unisonic technologies co., ltd 2 of 8 www.unisonic.com.tw qw-r502-638.a ? marking information package voltage code marking hsop-8 ad :adj utc date code lxxld15 g: halogen free l: lead free voltage code lot code ? pin configuration gnd fb v out v out v in v cntl p ok en 1 2 3 4 5 6 7 8 ? pin description pin no. pin name description 1 gnd ground pin. 2 fb there?s an external resistor divider connected to this pin which is necessary to give the feedback voltage to the regulator. the exter nal circuit is combined as the follow: between v out and fb is r1(connected with a bypa ss capacitor which can improve the load transient response),and between fb and ground is r2.the value of r2 and r1 are recommended between 100 ? ~10k ? .so the output voltage is equals: v out =0.8(1+ r2 r1 )(v) 3 v out 4 vout the output voltage pin of the regulator. there should be set an output capacitor to compensate for closed-loop and also to improve transient responses. it?s necessary to connect pin 3 and pin 4 together by wide tracks. 5 v in this pin is the main supply input. it?s necessary to connect the exposed pad and v in together for lower dropout voltage. monitoring this pin?s voltage can reset power-on. 6 v cntl power input pin of the control circuitry. connecting this pin to a +5v (recommended) supply voltage provides the bi as for the control circuitry. the voltage at this pin is monitored for power-on reset purpose. 7 pok output pin for power-ok signal output. being an open drain output, through senescing fb voltage, this pin can show the users the output voltage?s states. that?s this pin w ill be low under any of these two situations: the rising fb voltage is not above the v pok threshold; the falling fb voltage is below the v pnok threshold. that indicates the outpu t voltage is not ready for users. 8 en input enable control pin. t he output voltage can be shut down when this pin is below 0.3v. this pin?s voltage can be set higher than v cntl voltage by an internal 10 a current source, and then the regulator will begin working normally.
lxxld15 preliminary cmos ic unisonic technologies co., ltd 3 of 8 www.unisonic.com.tw qw-r502-638.a ? block diagram soft-start and control logic power on reset thermal limit current limit dealy uv eamp pok 0.4v v ref 0.8v 90% v ref + - + - + - fb fb en v cntl v out pok gnd v in
lxxld15 preliminary cmos ic unisonic technologies co., ltd 4 of 8 www.unisonic.com.tw qw-r502-638.a ? absolute maximum rating parameter symbol ratings unit supply voltage (v cntl to gnd) v cntl -0.3 ~ +7 v supply voltage (v in to gnd) v in -0.3 ~ +3.9 v en and fb to gnd v i/o -0.3 ~ v cntl +0.3 v pok to gnd v pok -0.3 ~ +7 v power dissipation p d 2.8 w lead soldering temperature, 10 seconds t sdr 260 junction temperature t j 150 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 oper ation is not implied. ? thermal characteristics parameter symbol ratings unit junction to ambient in free air (note 1) ja 44 c/w junction to case (note 2) jc 19 c/w notes: 1. ja is measured with the component mounted on a high effe ctive thermal conductivity test board in free air. the exposed pad of hsop-8 is soldered directly on the pcb. 2. the thermal pad temperature is measured on t he pcb copper area connected to the thermal pad of package. ? recommended operating conditions parameter symbol ratings unit supply voltage control v cntl 3.1 ~ 6 v supply voltage input v in 1.1 ~ 3.5 v v cntl =3.35% 0.8 ~ 1.2 v output voltage v cntl =5.05% v out 0.8 ~ v in -0.2 v output current i out 0 ~ 1.5 a junction temperature t j -40 ~ +125
lxxld15 preliminary cmos ic unisonic technologies co., ltd 5 of 8 www.unisonic.com.tw qw-r502-638.a ? electrical characteristics (refer to the typical application circ uit. these specifications apply over, v cntl = 5v, v in = 1.5v, v out = 1.2v and t a = -40 ~ 85c, unless otherwise specified. typical values refer to t a = 25c). parameter symbol test conditions min typ max unit v cntl nominal supply current i cntl en=v cntl , v fb is well regulated 0.4 1 2 ma v cntl shutdown current i sd en=gnd 180 380 a v cntl v cntl rising 2.7 2.9 3.1 v por threshold v in v thr v in rising 0.8 0.9 1.0 v v cntl 0.4 v por hysteresis v in v hys 0.5 v reference voltage v ref fb=v out 0.8 v output voltage accuracy i out =0a ~ 1.5a, t j = -40 ~ 125 -1.5 +1.5 % line regulation out in out v v v v cntl =3.3 ~ 5.5v -0.13 0.13 %/v load regulation out out v v i out =0a ~ 1.5a 0.06 0.15 % v out =1.2v 0.12 0.18 v v cntl =5v, i out =1.5a, t j =25 v out =2.5v 0.17 0.23 v v out =1.2v 0.25 v dropout voltage v d v cntl =5v, i out =1.5a, t j =-40 ~ +125 v out =2.5v 0.3 v v cntl =5v, t j =25 2.1 2.8 3.5 a current limit i lim v cntl =5v, i out =1.5a, t j =-40 ~ +125 1.8 a over temperature shutdown o ts t j rising 150 over temperature hysteresis o th 50 under-voltage threshold v fb falling 0.4 v en logic high threshold voltage v en rising 0.3 0.4 0.5 v en hysteresis 30 mv en pin pull-up current en=gnd 10 a soft-start interval t ss 2 ms pok threshold voltage for power ok v pok vfb rising 90% 92% 94% v ref pok threshold voltage for power not o k v pnok vfb falling 79% 81% 83% v ref pok low voltage pok sinks 5ma 0.25 0.4 v pok delay time t delay 1 3 10 ms
lxxld15 preliminary cmos ic unisonic technologies co., ltd 6 of 8 www.unisonic.com.tw qw-r502-638.a ? application information 1. power sequencing when there?s no main voltage applied at v in , it is suggested not to apply a voltage to v out for a long time. because the internal parasitic diode (between v out to v in ) will conduct and dissipate power, there?s no protection. 2. output capacitor a proper output capacitor to maintain stability and im prove transient response over temperature and current is necessary. proper esr (equivalent series resistance) and capacitance of the output capacitor should be selected properly for stability of the normal oper ation and good load transient response. many kinds of capacitors can be used as an output capacitor, such as ultra-low-esr capacitors (like ceramic chip capacitors), low-esr bulk capacitors (like solid tantalum, poscap, and aluminum electrolytic capacitors). and also the value of the output capacitors? can be increased without limit. in the applications with large stepping load current, t he low-esr bulk capacitors are normally recommended. decoupling ceramic capacitors are recommended to be plac ed at the load and ground pins very closely and also the impedance of the lay out must be minimized. 3. input capacitor in order to prevent the input rail from dropping, the proper i nput capacitor to supply cu rrent surge during stepping load transients is required. because the limited slew rate of the surge currents, more parasitic inductance needs more input capacitance. ultra-low-esr capacitors ( > 100mf, esr < 300mw) is recommended for the input capacitor. 4. feedback network the following figure shows the feedback network between v out gnd and fb pins. working with the internal error amplifier, the feedback network can prov ide proper frequency response for the utc lxxld15 .
lxxld15 preliminary cmos ic unisonic technologies co., ltd 7 of 8 www.unisonic.com.tw qw-r502-638.a ? typical application circuits 1. using an output capacitor with esr 18m ? 2. using an mlcc as the output capacitor utc lxxld15 pok en enable pok en gnd fb v out v out v in v cntl r3=1k ? r2=78k ? r1=39k ? c out =22f v out +1.2v/1.5a v in +1.5v c cntl =1f c in =22f c 1 =56pf v cntl +5v 1 2 4 3 5 6 7 8 v out (v) r1 (k ? ) r2 (k ? ) c1 (pf) 1.05 43 137.6 47 1.5 27 30.86 82 1.8 15 12 150
lxxld15 preliminary cmos ic unisonic technologies co., ltd 8 of 8 www.unisonic.com.tw qw-r502-638.a 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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