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1/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015/a/b/c 2a pwm buck dc/dc converter ? general description the AX3015 /a/b/c series are monolithic ic designed for a step - down dc/dc converter, and own the ability of driving a 2a load without additional transistor. it saves board space. the external shutdown func tion can be controlled by logic level and then come into standby mode. the internal compensation makes feedback control having good line and load regulation without external design. regarding protected function, thermal shutdown is to prevent over temper at ure operating from damage; current limit is against over current operating of the output switch that set by outside resistance . c urrent limit depends on r sense value . the o ver voltag e protection (ovp) that can avoid high v out voltage to damage circuit and capacitor , the ovp voltage is set by outside resistances . when scp happened and v en/ct >0.5v, the driver can be auto restart that can prevent driver damage. t he auto - restart time set by outside capacitor. the chip is available in sop-8l-ep package which features small size as exposed pad to reduce the junction- to -case resistance. ? features - operating voltage can be up to 40v . - adjustab le version output voltage range form 1.2 v to 30 v . - output load current: 2a. - e xternal ovp setting function. - operating frequency: a x3015/a : 130khz AX3015b/c: 50khz - voltage mode non - synchronous pwm converter - thermal - shutdown and current - limit protection . - s hutdown function and auto restart control . - short circuit protect (scp). - external current limit setting. - under voltage lockout. - sop - e p pb - free package . - built - in switching transistor on chip . v?mw`r?y?b? www.gofotech.com
2/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? block diagram ? pin assignment the package of AX3015 /a/b/c is sop - 8l - ep; the pin assignment is given by : name description v cc operat ing voltage input v ss gnd pin fb output voltage feedback control sw switch pin. connect external inductor and diode here sense1 current sense input1 sense2 current sense input2 en /ct sh utdown and auto restart control pin ovp over voltage detect pin ? order/marking information order information top marking 50 k / 130 khz osc . start - up and auto restart control + + _ thermal shutdown control + driver comp . vss sw fb 2 . 0 a switch _ comp . v cc current limit + _ amp current source bias 1 . 23 v reference 2 . 5 v regulator sense 1 1 . 08 v en / ct sense 2 140 mv + _ amp + _ amp 0 . 4 v scp ovp ovp 1 . 25 v ( top view ) 1 2 3 4 8 7 6 5 sw sop - 8 l - ep vss fb en / ct ovp vcc sense 1 vss sense 2 package type es : sop - 8 l - ep ax 3015 x x x packing blank : tube a : taping frequency / line comp . blank : 130 khz / 200 mv a : 130 khz / 0 mv b : 50 khz / 200 mv c : 50 khz / 0 mv logo y ax 3 part number id code : internal ww : 01 ~ 52 year : 10 = 2010 11 = 2011 0 1 5 y w w x blank : ax 3015 a : ax 3015 a b : ax 3015 b c : ax 3015 c x v?mw`r?y?b? www.gofotech.com
3/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? a bsolute m aximum r atings characteristics symbol rating unit maximum supply voltage v cc + 4 5 v en/ct , ovp pin input voltage - 0.3 to 6 v feedback pin voltage v fb - 0.3 to 12 v sw pin voltage v sw - 0.3 to v cc v sense pin voltage v sense 1/2 - 0.3 to 3 2 v power dissipation internally limited pd ( t j - t a ) / ja w storage temperature range t st - 65 to +150 c operating temperature range t op - 40 to +125 c operating supply voltage v op 8 to 40 v thermal resistance from junction to case jc 15 c /w thermal resistance from junction to ambient ja 40 c /w not e: ja is measured with the pcb copper area (need connect to exposed pad ) of approximately 1 in 2 ( multi - layer ) . ? e lectrical c haracteristics (unless otherwise specified, t a =25c, v cc =12v, v out =5v, i o ut = 0.2a) characteristics symbol conditions min typ max u nits feedback voltage v fb i out =10ma 1.0 69 1. 08 0 1. 091 v under voltage lockout u vlo falling - 6 - v uvlo hysteresis - 0.8 - v ovp detect voltage v ovp 1.2 25 1.2 5 1.2 75 v feedback bias current i fb v fb =1.5v - - 3 0 - na line regulation v cc =10~ 3 0v , i out =30ma - 0.5 1 % load regulation i out =0~1a, v out =5v r sense =0.1 AX3015a/c - - 5 - 25 mv AX3015/b +150 + 200 - quiescent current i ccq v fb =2v force driver off - 3 6 ma oscillator frequency f osc AX3015/a 115 130 155 khz AX3015b/c 40 50 60 max. duty cycle (on) dc v fb =0.6v force driver on - 100 - % min. duty cyc le (off) v fb = 1.5 v force driver off - 0 - saturation voltage v sa t no outside circuit v fb =0 .8 v force driver on i out =2a - 1.15 1.3 v i out =1a - 0.9 1.1 v sense voltage v sense v sense1 - v sense2 - 140 - mv sense voltage hysteresis v sense - h - 30 - mv sw pin leakage current sw pin=0v i sw l no outside circuit v fb =1.5v force driver off - - - 200 ua v?mw`r?y?b? www.gofotech.com
4/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c sw pin leakage current sw pin= - 0.8v v cc =40v force driver off - - 5 - ma en/ct pin logic input threshold voltage v en1 shutdown mode - - 0. 3 v v ct auto restart, v fb <0.4v 0. 5 - 1.5 v en2 operating mode 1.6 - - en/ct pin current i en/ct charge current - - 30 - ua en/ct pin current i en/ct discharge current - 1. 3 - ua thermal shutdown temp t sd - 160 - c thermal shutdown hysteresis t sh - 45 - c ? application c ircuit v out = v fb (1 + ) , v fb = 1.08 v , r2 = 5 k ~ 15 k v out (ovp) = v ovp (1 + ) , v fb = 1.25 v , r 4 = 5 k ~ 15 k ? f unction d escripti ons f b sense the regulated output voltage to complete the feedback loop , moreover, the external ovp and scp sense voltage. i f v fb >1.2 5 v , the ovp is happened that it can turn - off the driver, when v fb <0.4 v and v en/ct R 0.4 v , the scp is happened that it can auto restart driver . sense1/2 the current limit sense pin, if v sense1 - v s en se2 R 14 0mv, the over current is ha p pened that it can turn - off driver cycle by cycle. c 2 0 . 1 uf d 1 b 240 a l 1 1 2 c 3 470 uf c 1 470 uf u 1 vcc sw fb en / ct sense 2 vout = 5 . 0 v / 1 a vin = 10 ~ 30 v c 4 0 . 1 uf r 2 8 . 2 k r 1 30 k r sense vss ovp c 6 0 . 1 uf 1 3 5 4 2 7 6 8 c 5 sense 1 r 4 r 3 ax 3015 0 . 1 r c 7 3 . 9 nf 10 nf ? r2 r1 v?mw`r?y?b? www.gofotech.com
5/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ovp the over voltage sense p in , i f v ovp >1.2 5 v , the ovp is happened that it can turn - off th e driver. y ou can set vout ovp voltage by outside resistances ( r3 and r4) , please see below formula to set . en / ct the pin is enable/shutdown and auto restart control functions. w hen system is normal operating, this pin is enable/sh utdown function. pulling this pin below a threshold voltage of under 0.3 v shuts the regulator o ff , and pulling this pin from 0.5 v to 1.5 v turns the regulator on . however when v out is short (v fb <0.4v), the auto restart function can be started that restart t he regulator cycle by cycle. t he cycle time is set by outside capacitor (c6). please refer the below waveform and formula, the t2 cycle is regulator off time and t1 cycle is current limit time. t he charge - current is 3 0ua and discharge - current is 1 . 3 ua. ) ( . ) ( 4 3 1 25 1 r r vout ovp ? ? ? v en / ct time t 1 t 2 time iin ( a ) 0 . 5 v 1 . 5 v 0 current limit .) ( . t .) ( t sec u c sec u c 3 1 1 6 2 30 1 6 1 ? ? ? ? v?mw`r?y?b? www.gofotech.com
6/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c under voltage lockout (uvlo) to avoid mis-operation of the device at low input voltages an under voltage lockout is included that disables the device, if the input voltage falls below 6 .0 v. ? applicati on information setting the output voltage application circuit item shows the basic application circuit with adjustable output version. the external resistor sets the output voltage according to the following equation: table 1 resistor select for output voltage setting v out r 2 r 1 5.0 3 v 8.2 k 30 k 3.3 2 v 13 k 2 7 k current limit protection the current limit is set by outside resistance (r sense ), when the sense1 - sense2 voltage larger than 140mv, the current limit is happened that dri ver can be turned off until the drop is small than 110mv. the current limit set according to the following equation: t he maximum output current table is shown as below; please refer the table to design . rsense () current limit (a ) maximum output current (a) 100m 1.4 1.1 150m 0.93 0.7 200m 0.7 0.5 ? ? ? ? ? ? ? ? ? r r v v out . sense r m 140 ? (a) limit current v?mw`r?y?b? www.gofotech.com
7/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c line compensation (AX3015 and AX3015b only) the function is designed in order to compensate the output line loss, especially in heavy load. the AX3015/b s load regulation is p ositive; the v out voltage can be raised by output current. for example, v fb =1.08v in i out =0a, when i out increase to 1a, the v fb can be rise to about 1.123v. inductor selection for most designs, the different frequency can be reducing the inductor value; the AX3015 is suggested 68 h to 12 0 h for 50k to 130 khz frequencies. please refer the below table to design. l1 recommend value (v in = 10 ~ 3 0 v ,v out = 5 v, i out = 1 a) version AX3015 AX3015a AX3015b AX3015c l1 value (h) 68u~100u 68u~100u 100 u~ 120 u 100u~120u wh ere is inductor ripple current. large value inductors lower ripple current and small value inductors result in high ripple currents. choose inductor ripple current approximately 20 % of the maximum load current 2a, i l =0.4 a. the dc current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (2 a+ 0. 2a). input capacitor selection this capacitor should be located close to the ic using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage . the rms current rating requirement for the input capacitor of a buck regulator is approximately 1?2 the dc load current. a low esr input capacitor sized for maximum rms current must be used. a 470 f low esr capacitor for most applications is sufficient. output capacitor selection the output capacitor is required to filter the output and provide regulator loop stability. t he important capacitor parameters are; the 100 khz equivalent series resistance (esr), the rms ripples current rating, voltage rating, and capacitance value. for the output capacitor, the esr value is the most important parameter. the esr can be calculated from the following formula. v?mw`r?y?b? www.gofotech.com
8/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c = 0. 4 a x 8 0m= 32 mv an aluminum electrolytic capacitor's esr value is related to the capacitance and its voltage rating. in most case, higher voltage electrolytic capacitors have lower esr values. most of the time, capacitors with much higher v oltage ratings may be needed to provide the low esr values required for low output ripple voltage. system stability is depending on output capacitor s esr, correct to choose output capacitor s esr is very important . it is recommended to using a 220~ 470 f , the esr values range is 4 0 ~130m . thermal considerations the sop - 8 l - ep package needs a heat sink under most conditions. t he heat sink connect exposed pad of AX3015 to obtain best effect. the size of the heat sink depends on the input voltage, the output voltage, the load current and t he ambient temperature. esr i v l ripple ? ? ? v?mw`r?y?b? www.gofotech.com
9/ 13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? typical characteristics saturation voltage 0 0.3 0.6 0.9 1.2 1.5 0 400 800 1200 1600 2000 saturation voltage (v) iout (ma) vin=30v vin=10v line regulation 4.97 4.98 4.99 5.00 5.01 5.02 5.03 10 15 20 25 30 vin (v) vout (v) iout=30ma load regulation 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 0 200 400 600 800 1000 iout (ma) vout (v) vin=12v AX3015/b rsense=0.1 load regulation 4.80 4.85 4.90 4.95 5.00 5.05 5.10 5.15 5.20 5.25 5.30 0 200 400 600 800 1000 iout (ma) vout (v) vin=12v AX3015a/c temperature vs. vfb 1.060 1.065 1.070 1.075 1.080 1.085 1.090 1.095 1.100 -40 temperature vs. saturation voltage 0 0.4 0.8 1.2 1.6 2 -40 v?mw`r?y?b? www.gofotech.com
10/13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? typical characteristics (c ountinous ) 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 400 800 1200 1600 2000 iout (ma) current limit test vout (v) AX3015a/c vin=12v 56(16( 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 400 800 1200 1600 2000 iout (ma) current limit test vout (v) AX3015/b vin=12v 56(16( 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 200 400 600 800 1000 1200 iout (ma) current limit test vout (v) AX3015/b vin=12v 56(16( 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 200 400 600 800 1000 iout (ma) current limit test vout (v) AX3015/b vin=12v 56(16( temperature vs. uvlo 0 2 4 6 8 10 -40 efficency test 0 10 20 30 40 50 60 70 80 90 100 0 200 400 600 800 1000 1200 iout (ma) efficiency (%) vin=12v, vout=5v vin=20v, vout=5v vin=30v, vout=5v v?mw`r?y?b? www.gofotech.com
11 /13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? typical characteristics (c ountinous ) power - on power - on en - on en - on load transient (AX3015) load transient (AX3015) v?mw`r?y?b? www.gofotech.com
12/13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? typical characteristics (c ountinous ) load transient (AX3015a) load transient (AX3015a) load transient (AX3015b) load transient (AX3015b) load transient (AX3015c) load transient (AX3015c) v?mw`r?y?b? www.gofotech.com
13/13 axelite confidential materials, do not copy or distribute without written consent . rev. 1. 2 aug. 04 , 2010 AX3015 /a/b/c ? p ackage o utlines symbol dim ensions 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 v?mw`r?y?b? www.gofotech.com

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