ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 1 fax (925) 443-0723 general description the ams3121 is a high performance linear regulator with very low dropout voltage and excellent transient response. it is designed to operate with wide input voltage range of 1.5 ? 7volts making it ideal for two step conversion while maintaining high efficiency for many power sensitive applications. the device is capable of supplying 2a of output current with a typical dropout voltage of 550mv at 2a. the product is only available in a fixed output voltage option. the product includes complete shor t-circuit and thermal protection. the co mbination of these two internal protection circuits gives the device a comprehensive safety system to safe guard against extreme adverse operating conditions. the ams3121 is available in both 3-pin to-220 and to-263 packages , and it is rated for -40c to +125c temperature range. features ? v in range: 1.5 ? 7v ? fixed output voltage as low as 0.6v ? 2a maximum output current ? 550mv typical dropout voltage at 2a ? low self noise ? 125a typical supply current ? psrr >40db at 10khz ? stable with electrolytic, tantalum or ceramic capacitors ? current limit protection ? over-temperature shutdown ? -40 to +125c temperature range ? available in 3-pin to-220 and to-263 surface mount packages ? rohs & weee compliant applications ? set-top box ? dvd, blue-ray dvd writers ? lcd tvs and lcd monitors ? battery powered equipment ? infotainment ? wireless & rf: applications ? high efficiency ?green? laptops & notebook typical application
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 2 fax (925) 443-0723 pin description (to-220 and to-263 3-pin package) pin # symbol description 1 v in input supply voltage. it powers the internal control circuitry and the internal power switch. bypass v in with at ceramic capacitor from this pin to ground. 2 gnd ground 3 v out output voltage pin configuration
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 3 fax (925) 443-0723 absolute maximum ratings (1) maximum input supply voltage (v in )???....?...? -0.3v to 15v storage temperature range?????................ -65 ? c to 150 ? c lead temperature???????..????.???.?..? 260 ? c junction temperature???...???????..??..??..125 ? c recommended operating conditions (2) input voltage??????????.????.???.. 1.5v to 7v ambient operating temperature??.?.???? -40 ? c to 125 ? c thermal information to-220 3-pin ja .. ????...?????.????.?...50 ? c/w to-263 3-pin ja (3) ??????????.??????30 ? c/w electrical characteristics unless otherwise noted: v in =3.3v; v out =1.8v; c in =10 f; c out =22f; -40 ? c t a =t j 85 ? c; t j(max.) = 125 c; typical values are t a = 25 c parameter symbol conditions min. typ. max. units output voltage accuracy v out -3 3 % maximum output current i out_max 2 a load regulation i out = 0 ? 2a 0.1 % line regulation v in =3.0 ? 7.0v; i out =100ma 0.2 % supply current i sup v in =3.3v, io=0a 0.2 0.5 ma current limit i lim 2.5 a dropout voltage v do i out =0.1a; v out =95% of v out(nom) 85 mv i out =0.5a; v out =95% of v out(nom) 180 i out =1a; v out =95% of v out(nom) 275 i out =2a; v out =95% of v out(nom) 550 psrr v out / v in f=10khz io=20ma 40 db output noise voltage e n bw= 100hz ?100 khz c out = 10f i out = 500ma 125 v(rms) thermal shutdown t sd 145 c thermal shutdown hysteresis t sd_hys 15 c notes: 1. stresses above those listed in absolute maximu m ratings may cause permanent damage to the device. 2. measured on approximately 1? square of 1 oz. copper. 3. with package soldering to 0.5in 2 copper area over backside ground plane or internal power plane ja can vary from 20 c/w to > 40 c/w depending on mounting technique . the thermal resistance ju nction to case is 45 ? c/w. total power dissipation for the switching regulator and the ldo should be taken in consideration when calculating the output current capability of each regulator
t y ground current ( ma ) out p ut volta g e error ( % ) output voltage change (%) 02/11/201 0 y pical perf o 0 10 20 30 40 50 60 70 0.0 () gro -0.2 -0.1 0.0 0.1 0.2 3 pg() -0.2 -0.1 0.0 0.1 0.2 0.0 output voltage change (%) 0 o rmance c 0.4 0. 8 output c u und current v out =2. 5 4 input line regu l 0.1 outpu t load c haracteri s 8 1.2 u rrent (a) vs. output c 5 v, v in =3.3v 5 voltage (v) l ation v out = 1.0 t current (a) regulation www.a d s tics (t a = 2 1.6 2. 0 c urrent 67 2.5 v 10. 0 d vanced-mon o 4 2 5c unless o 0 0 output voltage (v) voltage (v) voltage (v) 2a fa s o lithic.com o therwise s p 1.792 1.794 1.796 1.798 1.800 1.802 1.804 1.806 1.808 -50 - out p 0.0 0.2 0.4 0.6 0.8 1.0 -50 - d 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0 dr o a s t transie n p ecified) - 25 0 2 a mbient t p ut voltage t - 25 0 2 a mbient t ropout volt a 0.5 output c o pout volta g a ms 3 n t linear r phone (925 ) fax (925 ) 2 5507 5 t emperature t emperature 2 5507 5 t emperatur e a ge vs. tem p 1a 2a 1 c urrent (a) g e vs. outp u v o 3 121 egulator ) 443-0722 ) 443-0723 5 100 12 5 (oc) variation 5 100 12 5 e (c) p erature 1.5 2 u t current o ut = 2.5v 5 5
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 5 fax (925) 443-0723 typical performance characteristics (t a = 25c unless otherwise specified) 100 sec/div v in start-up 0-550ma , v out =1.8 v, v in =3.3 v , c in =c out =22 f v in 1v/div v out 1v /div 10 sec/div load transient 100ma to 1.5 a , v out =1.8 v, v in =3.3 v , c in =c out =22 f i sw out 500ma / div v out 50mvac / div
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 6 fax (925) 443-0723 functional block diagram v ref = 0.6v r1 r2 + - error amp current limit over temperature v in gnd v out enable figure 1: block diagram of ams 3121 3-pin to-220 (t) / to-263 (m)
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 7 fax (925) 443-0723 device summary the ams3121 is a high voltage low drop out linear regulator with a current capability of up to 2a. the ldo has an input voltage range of 1.5v to 7v with an output voltage as low as 0.6v and is stable with a wide range of ceramic, t antalum, and electrolytic output capacitors. fault protection short circuit and over-tem perature shutdown disable the converter and ldo in the event of an overload condition. overtemp shut down disables the device when the junction temperature exceeds 145 oc. the output current is internally limited to 2.5a. input capacitor an input bypass capacitor ranging from 1f to 10f is required. the capacitor should be placed as close as possible to the device and not be placed more than 1 inch from the ldo. output capacitor the output capacitor requirements range from the minimum value required to guarantee stability to larger values required to meet the extreme transient response requirements. values range from 10 to 22f x5r ceramic capacitors. due to the extreme voltage coefficient of x5r ceramic capacitors, the voltage rating should be at least double the maximum applied voltage. pcb layout the following guidelines should be followed to insure proper layout. 1. v in capacitor. a low esr ceramic bypass capacitor must be placed as close to the ic as possible. 2. ground. 3. for good thermal performance vias are required to couple the exposed tab of both to-220 and to-263 packages to the pcb ground plane. the via diameter should be 0.3mm to 0.33mm positioned on a 1.2mm grid. output power and thermal limits the ams3121 junction temperature and current capability depends on the internal dissipation and the junction to case thermal resistance of the to-220 and to-263 exposed tab packages. additionally, the tab paddle and pcb temperature will be elevated due to the total losses of the ldo and of other circuits mounted to the pcb. tjmax=pd jc+tpcb+tamb the internal losses contribute to the junction temperature rise above the paddle and pcb temperature.
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 8 fax (925) 443-0723 figure 2: ams3121 to-263 3-pin option evaluation board - top side figure 3: ams3121 to-263 3-pin option evaluation board - bottom side figure 4: ams3121 evaluation board schematic table 1: evaluation board bill of materials component value manufacturer manufacturer part number c1,c2 22f, 10v, x5r, 0805, ceramic taiyo yuden lmk212bj226mg-t c3,c5,c4,c6 optional u1 low drop out linear regulator ams ams3131 c2 22uf vin vout c1 22uf c5 470uf *1 c6 22uf *2 c3 470uf *1 c4 22uf *2 gnd gnd c1, c2 22uf x5r 1210 10v ceramic capaci tor *1. optional electrolyti c capaci tor in place of ceramic capacitor *2. optional tantalum capacitor in place of ceramic capacitor vout 3 vin 1 gnd 2 u1 ams3121
ams3121 2a fast transient linear regulator 02/11/2010 www.advanced-monolithic.com phone (925) 443-0722 9 fax (925) 443-0723 ordering information device package ams3121t-xx (1)(2)(3) to-220 3-pin AMS3121M-XX (1)(2)(3) to-263 3-pin notes: 1. available in tape and reel only. a reel contains 2,500 devices. 2. available in lead-free package only. de vice is fully weee and rohs compliant 3. need to specify output voltage option ( ) outline drawing and landing pattern package dimensions are inches (millimeters) unless otherwise noted. 0.330 -0 .370 0.032 0 .060 (1 .524 ) typ ( 8. 382 -9.398 ) (5 .05 - 5.54 ) 0 .090 - 0 .110 ( 2.286 -2 .794 ) 0.199 -0 .218 (0.81) typ 0 .390 - 0 .415 ( 9.906 -10 .541 ) 0 .165 -0. 180 (4 .191 - 4. 572 ) 0 .045 - 0. 055 (1 .143 - 1. 397 ) 0 .095 - 0. 115 (2 .413 - 2. 921 ) 0.90 -0. 110 (2. 29- 2 .79 ) 0.013-0.023 (0.330 -0 .584 ) 0 .108 (2.74) typ ( 0.102 ) +0.203 -0.102 0.004 + 0 .008 - 0 .004 m (dd3) ams drw # 042191r1
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