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1/12 ax elite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 pwm control 2a step-down converter ? general description AX3106 cons ists of step-down switching regulator with pw m control. these devise include a reference voltage source, oscillation circuit, error amplifier, internal pmos and etc. AX3106 provides low-ripple power, hi gh efficiency, and excellent transient characteristics. the pwm control circuit is able to every the duty ratio linearly form 0 up to 100%. this converter also contains an error amp lifier circuit as well as a soft-start circuit that prevents overshoot at startup. an enable function, an over current protect function and short circuit protect function are built inside, and when ocp or scp happens, the operation frequency will be reduced. also, an internal co mpensation block is built in to minimum external component count. with the addition of an internal p-channel power mos, a coil, capacitors, and a diode connected externally, these ics can function as step-down switching regulators. they serve as ideal power supply units for port able devices when coupled with the sop-8l package, providing such outstanding features as low current consumption. since this converter can accommodate an input voltage up to 23v, it is also suitable for the operation via an ac adapter. ? fea tures - input voltage 3.6v to 23v - output voltage 0.8v to v cc - duty ratio 0% to 100% p wm control - oscillation frequency 330khz typ. - soft-start (ss), current li mit (cl), enable function. - thermal shutdown function. - short circuit protect (scp). - built-in internal sw p-channel mos. - low esr output capacitor (multi-layer chip capacitor (mlcc)) application. - sop-8l pb-free package. v?mw`r?y?b? www.gofotech.com
2/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? block diagram vcc oscillator circuit reference voltage pwm switched control circuit + - vss v en en comp fb thermal shutdown sw current limit with soft start ? pin assignmet the package of AX3106 is sop-8l; t he pin assignment is given by: name description fb feedback pin en power-off pin h normal operation(step-down) l step-down operation stopped (all circuits deactivated) comp compensation pin v cc ic power supply pin sw switch pin. connect external inductor/diode here. v ss gnd pin ? order/marking information order information top marking package type s: sop-8l AX3106 x x x packing blank : tube a : taping frequency blank : 330khz logo y ax 3 part number id code:internal ww: 01~52 year: 10=2010 11=2011 1 06 ywwx v?mw`r?y?b? www.gofotech.com
3/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? absolute maximum ratings (at t a =25 oc) characteristics symbol rating unit vcc pin voltage v cc v ss - 0.3 to v ss + 25 v feedback pin voltage v fb v ss - 0.3 to v cc v on/off pin voltage v en v ss - 0.3 to v cc + 0.3 v switch pin voltage v sw v ss - 0.3 to v cc + 0.3 v power dissipation pd internally limited mw storage temperature range t st -40 to +150 c operating junction temperature range t j -20 to +125 c operating supply voltage v op +3.6 to +20 v thermal resistance from junction to case jc 25 c/w thermal resistance from junction to ambient ja 70 c/w note: e ja is measured with the pcb copper area(need connect to sw pins) of approximately 1 in 2 (multi-layer). ? electrical characteristics (v in = 12v, t a =25c, unless otherwise specified) characteristics symbol conditions min typ max units feedback voltage v fb i out =0.2a 0.784 0.8 0.816 v quiescent current i ccq v fb =1.2v force driver of f 3 5 ma feedback bias current i fb i out =0.2a - 0.1 0.5 ua shutdown supply current i sd v en =0v - 2 10 ua current limit i cl 3.0 - - a line regulation v out /v out v cc =4v~23v, i out =0.2a - 0.6 1.2 % load regulation v out /v out i out = 0.2 to 2a - 0.15 0.3 % oscillation frequency f osc sw pin 260 330 400 khz en pin logic input threshold voltage v sh high (regulator on) 2.0 - - v v sl low(regulator off) - - 0.8 en pin input current i sh v en =2.5v (on) - 20 - ua i sl v en =0.3v (off) - -10 - ua soft-start time t ss - 20 - ms internal mosfet r dson r dson v cc =12v, v fb =0v - 70 - m ? efficiency effi v out = 5v i out = 1a - 92 - % i out = 2a - 92 - thermal shutdown temp t sd 125 c v?mw`r?y?b? www.gofotech.com
4/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? application circuit 1. mlcc c2 10uf*2 r1 39k l1 1 2 c6 0.1uf AX3106 1 2 3 4 5 6 7 8 fb en comp vcc sw sw vss vss c8 c1 1nf c4 r3 4.7k r4 100k r2 7.5k vout=5v3a c7 680pf d1 b340 vfb = 0.8 v ; r1 suggest 10k ~ 50k vout = vfb x on/off vcc+12v c3 10uf*3 0.1uf 0.1uf ( r1 r2 1 + ) option 15uh compensation capacitor selection(mlcc) v in v out l1 r3 c7 c1 12v 5.0/3.3/2.5v 15uh 4.7k 680pf 1nf 5v 3.3/2.5v 15uh 6.8k 470pf 1nf 2. el cap c2 470uf r1 30k l1 1 2 c6 0.1uf AX3106 1 2 3 4 5 6 7 8 fb en comp vcc sw sw vss vss c8 c1 1nf c4 r3 3.9k r4 100k r2 5.6k vout=5v2a c7 10nf d1 b340 vfb = 0.8 v ; r2 suggest 0.8k ~ 6.0k vout = vfb x on/off vcc+12v c3 470uf 0.1uf 0.1uf ( r1 r2 1 + ) option 15uh compensation capacitor selection(el cap) v in v out l1 r3 c7 c1 5-20v 5.0/3.3/2.5/1.8v 15 h 3.9k 10nf 1nf v?mw`r?y?b? www.gofotech.com
5/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? function descriptions pwm control the AX3106 consists of dc/dc converters that employ a pulse-width modulation (pwm) system. in converters of the AX3106, t he pulse width varies in a range from 0 to 100%, according to the load current. the ri pple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. therefore, these converters provide a low-ripple power over broad r anges of input voltage and load current. setting the output voltage application circuit item shows the basic application circuit with adjustable output version. the external resistor sets the out put voltage according to the following equation: ? ? ? ? ? ? ??? 2 1 18.0 r r v v out table 1 resistor select for output voltage setting v out c out r2 r1 5v el 1.3k 6.8k mlcc 7.5k 39k 3.3v el 1.5k 4.7k mlcc 15k 47k 2.5v el 2.2k 4.7k mlcc 22k 47k 1.8v el 2k 2.5k 1.5v el 2.2k 2.0k 1.2v el 3k 1.5k v?mw`r?y?b? www.gofotech.com
6/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 inductor selection for most designs, the operates with inductors of 15h to 33h. the inductor value can be derived from the following equation: ? ? f i v vvv l osc l in out in out ?? ?? ? ? where is inductor ripple current. large va lue inductors lower ripple current and small value inductors result in high rippl e currents. choose inductor ripple current approximately 15% of the maximum load current 2a, i l =0.3a. 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 (2a+0.15a). input capacitor selection (el cap) 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 c apacitor sized for maximum rms current must be used. a 220f low esr capacitor for most applications is sufficient. (mlcc) a 22f mlcc or greater capacitor for most applications is sufficient. note: mlcc do not support when v out is smaller than 2.5v. v?mw`r?y?b? www.gofotech.com
7/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 output capacitor selection (el cap) the output capacitor is required to filter the output and provi de regulator loop stability. the important capacitor param eters are; the 100khz e quivalent series resi stance (esr), the rms ripples current rating, voltage rating, and capacit ance value. for the output capacitor, the esr value is the most important par ameter. the esr can be calculat ed from the following formula. esr i v l ripple ??? = 0.33a x 130m ? = 43mv an aluminum electrolytic capacitor's esr value is related to the capacitance and its voltage rating. in most case, higher voltage electr olytic capacitors have lower esr values. most of the time, capacitors with much higher voltage ratings may be needed to provide the low esr values required for low output ripple voltage. it is recommended to replace this low esr capacitor by using a 330f low esr values < 130m. (mlcc cap) a 22f mlcc capacitor for most applications is sufficient. rds (on) current limiting the current limit threshold is setting by the internal circuit. v in 4v~4.6v 4.6v~8v 8v~20v i cl (min) 2.5a 2.8a 3.0a i out (max) 1.8a 2a 2a v?mw`r?y?b? www.gofotech.com
8/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 pcb layout guide if you need low tc and tj or large pd(power dissipation), the dual sw pins(5 and 6) and v ss pins(7 and 8)on the sop-8l package are internally connected to die pad, the pcb layout should allow for maximum possible copper area at the sw pins. 1. connect c3 to v cc and v ss pin as closely as possible to get good power filter effect. 2. connect ground side of the c2 and d1 as closely as possible. the heat sink copper of pcb area should be solder-painted without masked. use through hole to conduct the heat into the backside of pcb la y er. bypass c3 need closely from ic?s v cc to v ss pins. v?mw`r?y?b? www.gofotech.com
9/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? typical characteristics vfb vs vin 0.785 0.790 0.795 0.800 0.805 0.810 0.815 3 5 7 9 11 13 15 17 19 21 23 25 vin(v) vfb(v) iccq v s v in 0.0 1.0 2.0 3.0 4.0 5.0 6.0 3 5 7 9 11 13 15 17 19 21 23 25 vin(v) iccq(ma ) fosc v s v in 300.0 310.0 320.0 330.0 340.0 350.0 360.0 370.0 380.0 3 5 7 9 1113151719212325 vin(v) fosc(khz) fosc vs temperature 290.0 300.0 310.0 320.0 330.0 340.0 350.0 -20 0 20 40 60 80 100 120 temp ( ) fosc(khz) vfb vs temperature 0.785 0.790 0.795 0.800 0.805 0.810 0.815 -20 0 20 40 60 80 100 120 temp ( ) vfb(v) iccq vs temperature 0.0 1.0 2.0 3.0 4.0 5.0 6.0 -20 0 20 40 60 80 100 120 temp ( ) iccq(ma ) v?mw`r?y?b? www.gofotech.com
10/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? typical characteristics (mlcc) output ripple (v in =12v, v out =5v, i out =2a) power on test wave (v in =12v, v out =5v, i out =2a ) load transient response (v in =12v, v out =5v, i out =0.1~2a) en pin on test wave (v in =12v, v out =5v, i out =0.2a ) efficiency (v in =12v, v out =5v) efficiency (v in =12v, v out =3.3v) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0 0.5 1.0 1.5 2.0 iout (a) efficiency(%) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.00.51.01.52.0 iout(a) efficiency(%) v?mw`r?y?b? www.gofotech.com
11/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? typical characteristics (el cap) output ripple (v in =12v, v out =5v, i out =2a) power on test wave (v in =12v, v out =5v, i out =2a ) load transient response (v in =12v, v out =5v, i out =0.1~2a) en pin on test wave (v in =12v, v out =5v, i out =2a ) efficiency (v in =12v, v out =5v/3.3v) efficiency (v in =5v, v out =3.3v/2.5v) vin=12v 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.00.51.01.52.0 iout(a) efficiency(%) vout=5v vout=3.3v vin=5v 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.0 0.5 1.0 1.5 2.0 iout (a) efficiency(%) vout=2.5v vin=3.3v v?mw`r?y?b? www.gofotech.com
12/12 axelite confidential materials, do not copy or distribute without written consent . rev.2.1 mar.29, 2011 AX3106 ? package outlines detail a l h e a a2 a1 e d 7 (4x) b y c detail a symbol dimensions in millimeters dimensions in inches min. nom. max. min. nom. max. a - - 1.75 - - 0.069 a 1 0.1 - 0.25 0.04 - 0.1 a 2 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 v?mw`r?y?b? www.gofotech.com

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