1 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 300ma high psrr, low noise ldo regulator ? general description the AX6641 is a low dropout , high psrr, low noise linear regulator with very low quiescent . the device includes pass element, error amplifier, band - gap, current - limit and thermal shutdown circuit ry. the characteristics of low dropout voltage and less quiescent current make it good for some critical current application, for example, some battery powered devices. the typical quiescent current is approximately 8 0 a . in the shutdown mode, the maximum supply current is approximately 2 ua. due to internal flexible design, result in extensively fixed output voltage versions is 1.2v , 1.5v to 1.8 v . built - in current - limit and thermal - shutdown functions prevent any fault condition from ic damage. ? features - inpu t voltage range : 2.9 v~5.5 v - guaranteed 300ma output current - low quiescent current is 8 0a (typ.) - fixed output voltage is 1.2 v, 1.5v and 1.8v . - high psrr=85 db@1khz - fast transient response - current limit and thermal shutdown protection - available in the 5 - pin p b - free t sot - 2 3 package ? block diagram current limit - + vin vout gnd error amp bandgap thermal shutdown enable bp en 2 ua
2 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 ? pin assignment the package of AX6641 is t sot - 2 3 - 5l ; the pin assignment is given by : ? o rder/marking information order information top marking ( t sot - 2 3 - 5l) appendix part number identification code ax664 1 - 1 2 b t ma AX6641 - 1 5 b t mb ax664 1 - 1 8 b t mc ? absolute maximum ratings (at t a =25 c ) characteristics symbol rating 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 enable voltage v en gnd - 0.3 to gnd + 6 .5 v po wer dissipation pd 250 mw 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 jc 180 c/w thermal resistance from junction to ambient ja 250 c/w note : ja is measured with the pcb copper area of approximately 1 in 2 (multi - layer).that need connect to gnd pin. name description vin voltage input. the input capacitor in the range of 1 uf to 10uf is sufficient. gnd ground en enable pin (active high) bp reference noise bypass (the bypass capacitor R vout output voltage, the AX6641 is stable with an output capacitor. a x 6 6 4 1 x x x x x b t : t s o t - 2 3 - 5 l o u t p u t v o l t a g e p a c k a g e p a c k i n g b l a n k : t u b e a : t a p i n g 1 5 : 1 . 5 v 1 8 : 1 . 8 v - 1 2 : 1 . 2 v l identification code week : 01 ~ 26 ( a ~ z ) 27 ~ 52 ( a ~ z ) year : a = 2010 1 = 2011 id code : internal l y w x ( t o p v i e w ) t s o t - 2 3 - 5 l 3 2 5 4 1 v i n g n d e n b p v o u t
3 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 ? e lectrical c haracteristics (v in = 3 v whichever is greater, t a =25 c , un less otherwise noted) characteristics symbol conditions min typ max units input voltage v in i out =1 0ma 2. 9 - 5.5 v output voltage accuracy v out i out =1ma - 2 - +2 % quiescent current i q i out =0ma - 100 1 50 a (note 1 ) v drop i out =300ma v out =1.2 v - 1 6 00 1800 mv v out =1.5 v - 1300 1500 v out =1.8 v - 1000 1200 current limit i limit 4 00 - - ma line regulation v line i out =1ma, v in = 3 v to 5 .5 v - 1 5 mv load regulation (note 2 ) v load i out = 1 m~300ma - 6 20 mv ripple rejection psrr c o ut =2 .2 uf,i out =1ma f=1 00 hz - 90 - db f=1 k hz - 85 - enable input threshold v enh 1. 5 - - v v enl - - 0.4 enable pin current i e n v in =5v, v en = 0v - 2 4 a sd v in =5v, v en =0v - 2 5 a c i out =1ma, v in =5v - 50 - p pm/ c temperature shutdown t s - 160 - oc temperature shutdown hysterisis t sh - 25 - oc note 1 . the dropout voltage is defined as v in - v out , which is measured when v out drop about 100mv. note 2 . regulation is measured at constant junction temperature by using pulsed testing with a low on time. ? application circuit en c bp on off 1 uf vin vout gnd c in v in c out ax 6641 1 uf 2 . 2 uf v out en bp
4 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 ? application information like any low - dropout regulator, the AX6641 requires input and output decoupling capacitors. the device is specifically designed for port able 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 gua rding against oscillation caused by insufficient decoupling capacitance. capacitor selection normally, use a 1 f capacitor on the input and a 2.2 f capacitor on the output of the AX6641 . larger input capacitor values and lower esr provide better supply - noise rejection and transient response. a large value output capacitor may be necessary if large, fast transients are anticipated and the device is located several inches from the power source. the ca pacitors are recommended to use 2.2 uf x5r or x7r dielectric ceramic capacitors between device outputs to ground for transient stability. 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 volta ge is a function of drain - to source on - resistance, r ds (on) , multiplied by the load current: v dropout = v in - v out = r ds (on) x i out current limit and thermal shutdown protection in order to prevent overloading or thermal condition from damaging the devi ce, AX6641 regulator has internal thermal shutdown and current limiting functions designed to protect the device. it will rapidly shut off pmos pass element during overloading or over temperature condition. thermal considerations the AX6641 series can de liver a current of up to 300ma 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 125 c. with all possible conditions, the j unction 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 fo r any set of conditions can be estimated by the following thermal equation:
5 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 pd (max) = ( t j (max) - t a ) / j a where t j (max) is the maximum junction temperature of the die (125 c) and t a is the maximum ambient temperature. the junction to ambient thermal resistance ( ja ) for sot - 23 - 5 package at recommended minimum footprint is 250 c/w . pcb layout an input capacitance of ? 1 f is required between the AX6641 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 bo ards 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 sp ike caused by the surge current due to the inductive effect of the package pin and the printed circuit board s routing wire.
6 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 ? typical characteristics v in vs. v out 1.196 1.198 1.2 1.202 1.204 3 3.5 4 4.5 5 5.5 6 v in (v) v out (v) i out =1ma i out vs. v out 1.19 1.192 1.194 1.196 1.198 1.2 1.202 1.204 1.206 1.208 1.21 0 50 100 150 200 250 300 i out (ma) v out (v) v in =3.3v v in vs. i ccq 60 70 80 90 100 110 120 3 3.5 4 4.5 5 5.5 6 v in (v) i ccq (ua) i out =0ma v in vs. shutdown current 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 3 3.5 4 4.5 5 5.5 6 v in (v) shutdown current (ua) v en =0v v in vs. en threshold 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 3 3.5 4 4.5 5 5.5 6 v in (v) en (v) i out =100ma v enh v enl temperature vs. en threshold 0 0.2 0.4 0.6 0.8 1 1.2 -40 -20 0 25 50 85 105 125 temperature en (v) v enh v enl v in =3.3v
7 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 ? typical characteristics (continuous) v in vs. i en 0 0.5 1 1.5 2 2.5 3 3.5 4 3 3.5 4 4.5 5 5.5 6 v in (v) i en (ua) v en =0 v v in vs. dropout voltage 600 700 800 900 1000 1100 1200 1300 1400 1500 50 100 150 200 250 300 i out (ma) dropout voltage (v) v out =1.8v v out =1.5v v out =1.2v psrr 40 45 50 55 60 65 70 75 80 85 90 95 100 0.1 1 10 100 frequency (khz) psrr (-db) v in =5v, i out =30ma v out =1.8v v out =1.5v v out =1.2v
8 / 8 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 mar . 28 , 2 0 1 1 AX6641 ? package ou tlines symbol dimensions in millimeters dimensions in inches min. nom. max. min. nom. max. a - - 1.10 - - 0.043 a1 0.00 - 0.10 0 - 0.004 a2 0.70 0.90 1.00 0.028 0.035 0.039 b 0.30 0.40 0.50 0.012 0.016 0.020 c 0.08 0.1 4 0.20 0.003 0.006 0.008 d 2.80 2.90 3.00 0.110 0.114 0.118 e 2.60 2.80 3.00 0.102 0.110 0.118 e1 1.50 1.60 1.70 0.059 0.063 0.067 e 0.95 bsc. 0.037 bsc. e1 1.90 bsc. 0.075 bsc. l 0.30 0.45 0.60 0.012 0.018 0.024 l1 0.60 ref. 0.024 ref. l2 0.25 bsc . 0.010 bsc. y - - 0.10 - - 0.004 r 0.10 - - 0.004 - - 0 o - 8 o 0 o - 8 o jeced outline: mo - 193 ab e 1 e e e 1 b d a a 1 a 2 y l 1 r l c l 2
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