1 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 1.5a ultra low dropout linear regulator ? general description the AX6612 is a 1.5a ultra low dropout linear regulator. this product is specifically designed to provide well supply vol tage for front - side - bus termination on motherboards and nb applicatio ns. the ic needs two supply voltages, a control voltage for the circuitry and a main supply voltage for power conversion, to reduce power dissipation and provide extremely low dropout. the AX6612 integrates many functions. a power - on - reset (por) circuit mo nitors both supply voltages to prevent wrong operations. a thermal shutdown and current limit functions protect the device against thermal and current over - loads. a pok indicates the output status with time delay which is set internally. it can control oth er converter for power sequence. the AX6612 can be enabled by other power system. pulling and holding the en pin below 0.3v shuts off the output. the AX6612 is available in sop - 8 l - e p package which features small size as sop - 8 l and an exposed pad to red uce the junction - to - case resistance, being applicable in 2~3w applications. ? features - ultra low dropout - 0. 15 v(typical) at 1.5a output current - low esr output capacitor (multi - layer chip capacitors (mlcc)) applicable - 0.8v reference voltage - fast transient response - adjustable output voltage by external resistors - power - on - reset monitoring on both v cntl and v in pins - internal soft - start - under - voltage protection - current - limit and thermal shutdown protection - power - ok output with a delay time - sop - 8 l with expose d pad pb - free package.
2 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 ? b lock d iagram ? pin assignment the package of AX6612 is sop - 8l - ep ; the pin assignment is given by : name description gnd gnd pin fb feedback pin v out ic power supply pi n en internal pull high. en=high or floating ? ? pok power ok output pin vcntl cntl pin input voltage vin input voltage ? order/marking information order information top marking - + v i n v o u t g n d e r r o r a m p e n v c n t l s o f t - s t a r t a n d c o n t r o l l o g i c p o w e r - o n r e s e t c u r r e n t l i m i t e n a b l e t h e r m a l s h u t d o w n b a n d g a p f b - + p o k d e l a y p o k - + u v 0 . 4 v 9 0 % v r e f n - m o s f e t ( top view ) 1 2 3 4 8 7 6 5 vout vout sop - 8 l - ep ax 5913 gnd fb en pok vin vcntl vin package type es : sop - 8 l - ep ax 6612 x xx x packing blank : tube a : taping vout a : adj y ax 6 part number id code : internal ww : 01 ~ 52 year : 10 = 2010 11 = 2011 6 1 2 y w w x logo
3 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 ? absolute maximum ratings (at t a =25 oc ) characteristics symbol rating unit v cntl supply voltage v cntl - 0.3 to 7 v v in supply voltage v in - 0.3 to 6 v en and fb pin voltage v i/o - 0.3 to v cntl +0.3 v power good voltage v pok - 0.3 to 7 v power dissipation pd 3 w storage temperature range t st - 65 to +150 oc junction temperature range t j - 40 to 125 oc operating temperature range t op - 4 0 to +85 oc thermal resistance from junction to case jc 15 oc /w thermal resistance from junction to ambient ja 40 oc /w note: ja is measured with the pcb copper area(need connect to expose - pad ) of approximately 1.5 in 2 (multi - layer) ? recommended operating conditions characteristics symbol conditions rati ng unit v cntl supply voltage v cntl 3.1 to 6 v v in supply voltage v in 1.1 to 5 v output voltage v out v cntl =3.3v 0.8 to 1. 8 v v cntl =5v 0.8 to 3.3 v output current i out 0 to 1. 5 a ? electrical characteristics ( v cntl = 5v, v in = 1.5v, v out = 1.2v , t a =25 oc unless otherwise specified) characteristics symbol conditions min typ max units v cntl por threshold v cntl 2.7 2.9 3.1 v v cntl por hysteresis v cntl(hys) - 0.4 - v v in por threshold v in 0.8 0.9 1.0 v v in por hysteresis v in(hys) - 0.5 - v v cn tl nominal supply current i cntl en= v cntl 0.4 1 2 ma v cntl shuntdown current i sd en= 0v - 18 30 ua feedback voltage v fb v cntl =3.3 ~ 5v 0.784 0.8 0.816 v load regulation i out =0a ~ 1.5a - 0.06 0. 2 5 % dropout voltage v drop i out = 1.5a, v cntl =5v, t j = - 40 ~125 oc - 0.15 0.25 v internal mosfet r ds - on r ds - on v cntl - v out =2.5v,i out =1.5a - 100 - m cntl - v out =1.8v,i out =1.5a - 150 - v out pull low resistance en=0v - 90 120
4 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 ? electrical characteristics (continues) characteristics symbol conditions min typ max units soft start time t ss - 1 - ms en pin l ogic high threshold voltage v enh enab le 1.2 - - v v enl disable - - 0.4 en hysteresis - 30 - mv en pin pull - up current i en en=gnd - 10 - ua current limit i lim v cntl =3.3~5v, t j = - 40 ~ 125 oc 1.7 - - a ripple rejection v in psrr f=120hz, i out =100ma - 65 - db v cntl - 65 - un der - voltage threshold vfb falling - 0.4 - v pok threshold voltage for power ok v pok vfb rising 89% 92% 95% vfb pok threshold voltage for power not ok v pnok vfb falling 78% 81% 84% vfb pok low voltage pok sinks 5ma - 0.25 0.4 v pok delay time t delay 0.8 2 10 ms thermal shutdown temp t sd - 150 - oc thermal shutdown hysteresis t sh - 50 - oc
5 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 ? application circuit 1. using an output capacitor with es r R 20m 2. using an mlcc as the output capacitor ? function descriptions fb connecting this pin to an external resistor divider receives the feedback voltage of the regulator. the output voltage set by the resistor divider is determined b y: c 1 1 uf r 1 1 k vout = 1 . 2 v / 1 . 5 a vin = 1 . 5 v r 3 1 k vcntl = 5 v c 4 220 uf c 5 0 . 1 u u 1 ax 6612 6 2 4 1 3 8 7 5 vcntl fb vout gnd vout en pok vin c 2 100 uf c 3 0 . 1 uf c 6 12 ~ 48 nf r 2 2 k off on vin = 1 . 5 v r 3 1 k vout = 1 . 2 v / 1 . 5 a vfb = 0 . 8 v u 2 ax 6612 6 2 4 1 3 8 7 5 vcntl fb vout gnd vout en pok vin c 6 56 pf c 5 22 u c 1 1 uf c 3 22 uf vout = vfb *( 1 + r 1 / r 2 ) vcntl = 5 v r 2 78 k r 1 39 k off on
6 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 where r1 is connected from v out to fb with kelvin sensing and r2 is connected from fb to gnd. a bypass capacitor may be connected with r1in parallel to improve load transient response. the recommended r 2 and r1 are in the range of 1 k ~10 0 k . vin and exposed pad main supply input pins for power conversions. the exposed pad provides a very low impedance input path for the main supply voltage. please tie the exposed pad and vin pin (pin 8) together to reduce the dropout voltage. the voltage at this pin is monitored for power - on reset purpose. vcntl power input pin of the control circuitry. connecting this pin to a +5v (recommended) supply voltage provides the bias for the control circuitry. the voltage at this pin is monitored for powe r - on reset purpose. pok power - ok signal output pin. this pin is an open - drain output used to indicate status of output voltage by sensing fb voltage. this pin is pulled low when the rising fb voltage is not above the v pok threshold or the falling fb voltage is below the v pok threshold, indicating the output is not ok. en enable control pin. pulling and holding this pin below 0.3v shuts down the output. when re - enabled, the ic undergoes a new soft - start cycle. left this pin open, this pin is in ternal pulled up to v cntl voltage, enabling the regulator. vout output of the regulator. please connect pin 3 and 4 together using wide tracks. it is necessary to connect an output capacitor with this pin for closed - loop compensation and improving t ransient responses.
7 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 power - on - reset a power - on - reset (por) circuit monitors both input voltages at v cntl and v in pins to prevent wrong logic controls. the por function initiates a soft - start process after the two supply voltages exceed their rising por th reshold voltages during powering on. the por function also pulls low the pok pin regardless the output voltage when the v cntl voltage falls below its falling por threshold. internal soft - start an internal soft - start function controls rise rate of the out put voltage to limit the current surge at start - up. the typical soft - start interval is about 1 ms. output voltage regulation an error amplifier working with a temperature compensated 0.8v reference and an output nmos regulates output to the preset voltage . the error amplifier designed with high bandwidth and dc gain provides very fast transient response and less load regulation. it compares the reference with the feedback voltage and amplifies the difference to drive the output nmos which provides load cur rent from v in to v out . current - limit the AX6612 monitors the current via the output nmos and limits the maximum current to prevent load and AX6612 from damages during overload or short circuit conditions. under - voltage protection (uvp) the ax 6612 monitors the voltage on fb pin after soft - start process is finished. therefore the uvp is disabling during soft - start. when the voltage on fb pin falls below the under - voltage threshold, the uvp circuit shuts off the output immediately. after a while, the AX6612 starts a new soft - start to regulate output.
8 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 thermal shutdown a thermal shutdown circuit limits the junction temperature of AX6612 . when the junction temperature exceeds +150c, a thermal sensor turns off the output nmos, allowing the d evice to cool down. the regulato r regulates the output again through initiation of a new soft - start cycle after the junction temperature cools by 50c, resulting in a pulsed output during continuous thermal overload conditions. the thermal shutdown designed ? typical characteristics 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 3 3.5 4 4.5 5 5.5 6 v cntl (v) dropout voltage (v) v cnt l vs dropout v out = 1.2v 0 0.05 0.1 0.15 0.2 0.25 0.3 1.0v 1.2v 1.5v 1.8v 2.5v 3.3v v out (v) dropout voltage (v) v out vs dropout v cntl =5v v cntl =3.3v 0 0.05 0.1 0.15 0.2 0.25 -40 -25 0 25 50 75 100 temperature () dropout voltage (v) temperature vs dropout vcntl=5v v cntl =3.3v v out =1.2v temperature vs v fb 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 -40 -25 0 25 50 75 100 temperature () v fb (v) v in =1.5v v cntl =5v
9 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 ? typical characteristics (continues) line regulation (v out ) 1.12 1.14 1.16 1.18 1.2 1.22 1.24 1.26 1.28 3 3.5 4 4.5 5 5.5 6 v cntl (v) v out (v) v in =1.5v i out =10ma line regulation (vfb) 0.78 0.785 0.79 0.795 0.8 0.805 0.81 0.815 0.82 3 3.5 4 4.5 5 5.5 6 v cntl (v) v fb (v) v in =1.5v i out =10ma load regulation(v out ) 1.195 1.197 1.199 1.201 1.203 1.205 1.207 1.209 1.211 1.213 1.215 0 0.3 0.6 0.9 1.2 1.5 i out (a) v out (v) v in =1.5v v cntl =5v load regulation(v fb ) 0.780 0.785 0.790 0.795 0.800 0.805 0.810 0.815 0.820 0 0.3 0.6 0.9 1.2 1.5 i out (a) v fb (v) v in =1.5v v cntl =5v
10 / 10 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 4 jul . 06 , 20 10 AX6612 ? package outlines symbol dimensions in millimeters dimensions in inches min. nom. max. min. nom. max. a - - 1.75 - - 0.069 a1 0 - 0.15 0 - 0. 06 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 x - 2.34 - - 0.092 - y - 2.34 - - 0.092 - 0 o - 8 o 0 o - 8 o mold flash shall not exceed 0.25mm per side jedec outline: ms - 012 ba detail a l h e a a 2 a 1 e d 7 ( 4 x ) b y c detail a y x expose pad
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