1/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 1.5 a high output current ldo regulator ? general description the AX6643 is a low noise, high output current, low quiescent current and low dropout linear regulator. the device includes pass element, error amplifier, band-gap, current limit and thermal shutdown circuitry. the output current is up to 1.5 a, the characteristics of low dropout voltage and less quiescent current make it good for some critical current application , and for example, some battery powered devices. the typical quiescent current is approximately 50 a . in the shutdown mode, the maximum supply current is less than 2ua. built-in current-limit, short current protection and thermal-shutdown functions prevent any fault condition from ic damage. ? features - input voltage range : 2.6 v~ 5.5 v - adjustab le output voltage form 0.8v to 5.0 v - dropout voltage is 45 0mv at 1 .5 a output current @ v out = 3.30v - guaranteed 1. 5 a output current - low quiescent current is 5 0a (typ.) - maximum su pply current in shutdown mode < 2 ua - fast transient response - current limit and t hermal shutdown protection - short circuit current fold - back - available in the sop - 8l , to252 - 5l and t dfn - 6l pb - free package s ? b lock d iagram current limit - + vin vout gnd err or amp ban dgap t hermal shutdown ena ble en fb bp v?mw`r?y?b? w w w . g o f o t e c h . c o m
2/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ? pin assignment the package s of AX6643 are sop - 8l , to252 - 5l and t dfn - 6l; the pin assignm ent is given by : name description vin input voltage gnd ground vout regulator output voltage. adjustable from 0.8v to 5.5v. en active - low shutdown input. a logic low reduces the supply current to less than 2 a. connect to v in or floating for normal operation. fb feedback input for setting the output voltage. connect to an external resistor divider for adjustable output operation. bp band - gap ( t dfn - 6l only) ? or der/marking information order information top marking (sop - 8l/to252 - 5l) top marking ( t dfn - 6l) ( top view ) 1 2 3 4 8 7 6 5 vout fb sop - 8 l ax 6643 en vin gnd gnd gnd gnd to 252 - 5 l 1 en 4 vout 3 gnd 2 vin 5 fb ( top view ) ( side view ) metal tab gnd t d f n - 6 l ( 2 * 2 ) e n v o u t f b 1 2 3 4 5 6 b p g n d v i n ( t o p v i e w ) g n d ax 6643 xx x s : sop - 8 l package packing blank : bulk a : taping d 5 : to 252 - 5 l z 6 : tdfn - 6 l ( 2 * 2 ) logo y ax 6 part number id code : internal ww : 01 ~ 52 year : 10 = 2010 11 = 2011 6 4 3 y w w x m year : a = 2010 1 = 2011 week : 01 ~ 26 ( a ~ z ) 27 ~ 52 ( a ~ z ) id code : internal 1 y w x ax 6643 v?mw`r?y?b? w w w . g o f o t e c h . c o m
3/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ? absolute maximum ratings (at t a =25 c ) characteristics symbol ratin g unit v in pin voltage v in gnd - 0.3 to gnd + 6 .5 v output voltage v out gnd - 0.3 to v in + 0.3 v en pin voltage v en gnd - 0.3 to v in + 0.3 v fb /bp pin voltage v fb /bp gnd - 0.3 to v in + 0.3 v power dissipation sop - 8l pd 1. 65 w to252 - 5l 2.22 t dfn - 6l 0.83 storage temperature range t st - 40 to +150 c operating temperature range t op - 40 to +85 c junction temperature t j - 40 to +125 c thermal resistance from junction to case sop - 8l jc 20 c /w to252 - 5l 10 t dfn - 6l 25 thermal resistance from junction to ambient sop - 8l ja 60 c /w to252 - 5l 45 t dfn - 6l 120 note : ja is measured with the pcb copper area of approximately 1 in 2 (multi - layer). that need connect to gnd / tap pin . ? electrical characteristics t a =25 c (unless otherwise noted) characteristics symbol conditions min typ max units input voltage v in i out =30ma 2.6 - 5.5 v fb voltage v fb v in =2.6v to 5.5 v, i out =1ma 0.784 0.8 0.816 v fb input leakage current i fb v fb =0.8 v - 100 - 100 na adjustable output voltage range v out v fb - 5. 0 v quiescent current i q i out =0ma, v in =5v - 5 0 80 a shutdown current i sd i out =0ma, v en =0v - - 2 a dropout voltage v drop i out = 1. 5 a v out =1. 2 0v - 1. 3 1. 7 v v out =1.50v - 1. 0 1. 4 v out =1.80v - 0.70 1. 1 v out =2.50v - 0. 55 0. 75 v out =3.30v - 0. 45 0. 6 5 current limit (note 1 ) i limit 1.6 2.0 - a short circuit current i short v fb < 0. 2 v - 600 - ma load regulation (note 2 ) v load i out =10m~ 1. 5 a - 0. 5 1 % ripple rejection psrr c in =2.2f, c o =2.2uf, i out =10ma f=120hz - 65 - db f=1khz - 6 0 - enable input threshold v enh regulator enable 2 .0 - - v v enl regulator shutdown - - 0.6 enable pin current i enh v en =v in - 0.003 0.1 a i enl v en =0v - 1.0 1.5 v?mw`r?y?b? w w w . g o f o t e c h . c o m
4/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ? electrical characteristics (continuous) temperature shutdown t s - 150 - oc temperature shutdown hysterisis t sh - 30 - oc note 1 : current limit is measured at constant junction temperature by using pulsed testing with a low on time. note 2 : regulation is measured at constant junction temperature by using pulsed testing with a low on time. ? a pplication c ircuit 1. sop - 8l /to252 - 5l 2. t dfn - 6l ? f unction d escription a minimum of 2.2f capacitor must be connected from v out to ground to insure stability. typically a large storage capacitor is connected from v in to ground to ensure that the input voltage does not sag below the minimum dropout voltage during the load transient response. this pin must always be dropout voltage higher than v out in order for the device to regulate properly. on off vin vout gnd in c v in out c ax 6643 2 . 2 uf 2 . 2 uf out v en fb r 1 r 2 v out = v fb *( 1 + r 1 / r 2 ) v fb = 0 . 8 v r 2 range = 50 k ~ 300 k on off vin vout gnd in c v in out c ax 6643 2 . 2 uf 2 . 2 uf out v en fb r 1 r 2 bp c bp 10 nf v?mw`r?y?b? w w w . g o f o t e c h . c o m
5/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 enable function the AX6643 features an ldo regulator enable/d isable function. to assure the ldo regulator will switch on; the en turn on contr ol level must be greater than 2.0 volts. the ldo regulator will go into the shutdown mode when the voltage on the en pin falls below 0. 6 volts. for to protecting the system, t he AX6643 have a quick - discharge function. if the enable function is not needed in a specific application, it may be tied to vin to keep the ldo regulator in a continuously on state . fb function the output is an adjustable version, the fb voltage is 0.8v. the output voltage can be set by outside resistances. the output voltage, v out, is then given by the following equation: v out = 0.8* (1 + r1/r2) for the reasons of reducing power dissipation and loop stability, r2 is recommending to choose 50 k~3 00k . ? a pplication i nformation like any low-dropout regulator, the AX6643 requires input and output decoupling capacitors. the device is specifically designed for portable applications requiring minimum board space and smallest components. these capacitors must be correctly selected for good performance. please note that linear regulators with a low dropout voltage have high internal loop gains which require care in guarding against oscillation caused by insufficient decoupling capacitance. capacitor selectio n normally, use a 2.2f capacitor on the input and a 2.2f capacitor on the output of the AX6643. larger input capacitor values and lower esr (x5r, x7r) provide better supply-noise rejection and transient response. a higher- value output capacitor (4.7 f) may be necessary if large, fast transients are anticipated and the device is located several inches from the power source. input-output (dropout) voltage a regulator's minimum input- to -output voltage differential (dropout voltage) determines the lowest usable supply voltage. in battery-powered systems, this determines the useful end- of -life battery voltage. because the device uses a pmos, its dropout voltage is a function of drain-to source on -resistance, r ds (on) , multiplied by the load current: v dropo ut = v in -v out = r ds (on) x i out v?mw`r?y?b? w w w . g o f o t e c h . c o m
6/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 current limit an d short-circuit protection the AX6643 used a current sense-resistor to monitor the output current. a portion of the pmos output transistors current is mirrored to a resistor such that the voltage acros s this resistor is proportional to the output current. once the output current exceeds limit threshold, AX6643 would be protected with a limited output current. further more, when the output is short to ground, the output current would be folded-back to a less limit. thermal considerations the AX6643 series can deliver a current of up to 1. 5a over the full operating junction temperature range. however, the maximum output current must be dated at higher ambient temperature to ensure the junction temperature does not exceed 125c. with all possible conditions, the junction temperature must be within the range specified under operating conditions. power dissipation can be calculated based on the output current and the voltage drop across regulator. pd = (v in - v out ) i out the final operating junction temperature for any set of conditions can be estimated by the following thermal equation: pd (max) = (t j (max) - t a ) / ja where t j (max) is the maximum junction temperature of the die (125c) and t a is the maximum ambient temperature. the junction to ambient thermal resistance ( ja ) for sop- 8l package at recommended minimum footprint is 60 c/w that is connected 1 in 2 pcb copper area to gnd pin. pcb layout an input capacitance of ? 2.2f is required between the AX6643 input pin and ground (the amount of the capacitance may be increased without limit), this capacitor must be located a distance of not more than 1cm from the input and return to a clean analog ground. input capacitor can filter out the input voltage spike caused by the surge current due to the inductive effect of the package pin and the printed circuit boards routing wire. otherwise, the actual voltage at the v in pin may exceed the absolute maximum rating. the output capacitor also must be located a distance of not more than 1cm from output to a clean analog ground. because it can filter out the output spike caused by the surge current due to the inductive effect of the package pin and the printed circuit board s routing wire. v?mw`r?y?b? w w w . g o f o t e c h . c o m
7/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ? typical characte ristics v in vs.i ccq 20 30 40 50 60 70 80 2.6 3 3.5 4 4.5 5 5.5 v in (v) i ccq (ua) i out =0ma v in vs. i sd 0 0.2 0.4 0.6 0.8 1 1.2 1.4 2.6 3 3.5 4 4.5 5 5.5 v in (v) i sd (ua) v en =0v v in vs. i cl 0 1 2 3 4 5 2.6 3 3.5 4 4.5 5 5.5 v in (v) i cl (a) v out =1.2v v in vs. threshold voltage 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.6 3 3.5 4 4.5 5 5.5 v in (v) v enh /v enl (v) v enh v enl temperature vs. i ccq 0 10 20 30 40 50 60 70 80 90 100 -40 load regulation 1.14 1.16 1.18 1.2 1.22 1.24 1.26 0 0.01 0.1 0.3 0.5 0.8 1 1.2 1.5 i out (a) v out (v) v in =3.3v v?mw`r?y?b? w w w . g o f o t e c h . c o m
8/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ? typical characteristics (continuous) en - on (sop - 8l only) power - on thermal shutdown release load transient i out vs. dropout voltage 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 0.1 0.3 0.5 0.8 1 1.2 1.5 i out (a) dropout voltage (mv) v out =1.2 v out =1.5 v out =1.8 v out =2.5 v out =3.3 v out =5.0 temperature vs. v fb 0.750 0.760 0.770 0.780 0.790 0.800 0.810 0.820 0.830 -40 -20 0 25 50 75 100 125 temperature ( v?mw`r?y?b? w w w . g o f o t e c h . c o m
9/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ? package outlines (1) sop - 8l symbol dimensions in millimeters dimensions in inches min. nom. max. min. nom. max. a - - 1.75 - - 0.069 a1 0.1 - 0.25 0.04 - 0.1 a2 1.25 - - 0.049 - - c 0.1 0.2 0.25 0.0075 0.008 0.01 d 4.7 4.9 5.1 0.185 0.193 0.2 e 3.7 3.9 4.1 0.146 0.154 0.161 h 5.8 6 6.2 0.228 0.236 0.244 l 0.4 - 1.27 0.015 - 0.05 b 0.31 0.41 0.51 0.012 0.016 0.02 e 1.27 bsc 0.050 bsc y - - 0.1 - - 0.004 0 o - 8 o 0 o - 8 o mold flash shall not exceed 0.25mm per side jedec outline: ms-012 aa detail a l h e a a 2 a 1 e d 7 ( 4 x ) b y c detail a v?mw`r?y?b? w w w . g o f o t e c h . c o m
10/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 (2) to252 - 5l symbol dimensions in millimeters dimensions in inches min. nom. max. min. nom. max. a 6.35 6.6 6.73 0.250 0.260 0. 265 b 5.21 5.33 5.46 0.205 0.210 0.215 c 6.86 7.24 7.62 0.270 0.285 0.300 d 2.67 ref 0.105 ref p 1.27 ref 0.050 ref h 2.18 2.29 2.39 0.086 0.090 0.094 j 0.46 0.51 0.58 0.018 0.020 0.023 k 0.00 0.08 0.13 0.000 0.003 0.005 l 1.40 1.60 1.78 0.055 0.06 3 0.070 m 5.33 5.46 5.59 0.210 0.215 0.220 b 0.38 0.56 0.71 0.015 0.022 0.028 b1 0.38 0.53 0.66 0.015 0.021 0.026 mold flash shall not exceed 0.005inch per side b a b b 1 m d h j 5 . 8 1 1 . 0 5 . 8 2 . 0 1 . 27 land pattern recommendation ( unit : mm ) 7 . 2 0 . 6 p ( typ .) c k l v?mw`r?y?b? w w w . g o f o t e c h . c o m
11/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 jul. 30 , 20 10 AX6643 ( 3 ) t dfn - 6l ( 2*2 0.75mm ) symbol dimensions i n millim eters dimensions i n inches min. nom. max. min. nom. max. a 0.70 0.75 0.80 0.028 0.030 0.031 a1 0.00 0.02 0.05 0.000 0.001 0.002 a3 0.203 ref. 0.008 ref . b 0.2 0 0.2 8 0.3 5 0.009 0.011 0.013 d 1.95 2.00 2.05 0.077 0.079 0.081 d2 1. 35 1.5 0 1.6 5 0.055 0 .059 0.063 e 1.95 2.00 2.05 0.07 7 0.079 0.081 e2 0. 75 0.9 0 1.0 5 0.031 0.035 0.039 e 0.65 bsc. 0.026 bsc. l 0.20 0.3 0 0.4 0 0.008 0.012 0.016 e d a a 1 a 3 d 2 e e 2 ( top view ) ( bottom view ) b pin 1 l seating plane ( side view ) v?mw`r?y?b? w w w . g o f o t e c h . c o m
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