1/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 1. 2 a pwm buck dc/dc converter ? general description the AX3016 /a series are monolithic ic designed for a step - down dc/dc converter, and own the ability of driving a 1. 2 a load without additional transistor. it saves board space. the external shutdown fun ction can be controlled by logic level and then come into standby mode. the outside compensation makes feedback control having good line and load regulation. regarding protected function, thermal shutdown is to prevent over temperature operating from damag e; current limit is against over current operating of the output switch that set by outside resistance. current limit depends on r sense value. the over voltage protection (ovp) that can avoid high v out voltage to damage circuit and capacitor, the ovp volta ge is set by outside resistances. the chip is available in sop-8l-ep package which features small size as exposed pad to reduce the junction- to -case resistance. ? features - ope rating voltage can be up to 40v - adjustable vers ion output voltage range form 3.3 v to 30v. - output load current: 1. 2 a - external ovp setting function - operating frequency: 50khz - current mode non - synchronous pwm converter - thermal - shutdown and current - limit protection. - shutdown and soft - start function. - short circuit pro tect (scp) - external curr ent limit setting - under voltage lockout - sop - 8l- ep pb - free package - line - compensation v?mw`r?y?b? w w w . g o f o t e c h . c o m
2/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 ? block diagram ? pin assignment the package of AX3016 /a is sop - 8l- ep; the pin assignment is given by: name description sw switch pin. connect external inductor and diode here sense1 current sense input1 sense2 current sense input2 ovp over voltage detect pin fb output voltage feedback control en/ct shutdown and auto restart control pin v ss gnd pin v cc operating voltage input ? order/marking information order information top marking 5 0 k / 1 3 0 k h z o s c . s t a r t - u p s o f t - s t a r t + + _ t h e r m a l s h u t d o w n c o n t r o l + d r i v e r c o m p . v s s s w f b 1 . 2 a s w i t c h _ c o m p . v i n c u r r e n t l i m i t + _ a m p c u r r e n t s o u r c e b i a s 1 . 2 3 v r e f e r e n c e 2 . 5 v r e g u l a t o r s e n s e 1 1 . 0 8 v e n / c t 1 4 0 m v + _ a m p + _ a m p 0 . 4 v s c p o v p o v p s e n s e 2 ( t o p v i e w ) 1 2 3 4 8 7 6 5 s w s o p - 8 l - e p v s s f b e n / c t o v p v c c s e n s e 1 v s s s e n s e 2 p a c k a g e t y p e e s : s o p - 8 l - e p a x 3 0 1 6 x x x p a c k i n g b l a n k : t u b e a : t a p i n g f r e q u e n c y b l a n k : 5 0 k h z a : 1 3 0 k h z a x 3 l o g o p a r t n u m b e r i d c o d e : i n t e r n a l w w : 0 1 ~ 5 2 y e a r : 1 0 = 2 0 1 0 1 1 = 2 0 1 1 y y w w x 0 1 6 v?mw`r?y?b? w w w . g o f o t e c h . c o m
3/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 ? absolute maximum ratings characteristics symbol rating unit maximum supply voltage v cc +45 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 sense1/2 - 0.3 to 32 v power dissipation internally limited pd ( t j - t a ) / ja w storage temperature range t st - 65 to +150 c operati ng 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 note: ja is measured with the pcb copper area (need connect to exposed pad) of approximately 1in 2 (multi - layer). ? electrical characteristics (unless otherwise specified, t a =25c, v in =12v, v out =5v, i out = 0.2a) characteristics symbol conditions min typ max units feedback voltage v fb i out =10ma 1.058 1.080 1.102 v u nder voltage lockout u vlo falling - 5 - v uvlo hysteresis - 1 - v ovp detect voltage v ovp 1.193 1.230 1.267 v feedback bias current i fb v fb =1.5v - - 30 - na line regulation v in =10~30v, i out =10ma - 0.5 1 % load regulation i out =0~1a, v out =5v r sense = 0.1 + 20 0 +2 5 0 + 30 0 mv quiescent current i ccq v fb =1.5v force driver off - 5 8 ma oscillator frequency f osc 35 50 65 khz max. duty cycle (on) dc v fb =0.6v force driver on - 100 - % min. duty cycle (off) v fb =1.5v force driver off - 0 - saturation volt age v sat no outside circuit v fb =0.8v force driver on i out =1. 2 a - 1.1 1.3 v sense voltage v sense v sense1 - v sense2 130 1 4 0 150 mv v?mw`r?y?b? w w w . g o f o t e c h . c o m
4/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 ? electrical characteristics ( continue d ) sense voltage hysteresis v sense - h - 50 - mv sw pin=0v sw pin leakage current i swl no outside circuit v fb =1.5v force driver off - - - 200 ua sw pin= - 0.8v v in =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 <0.40v 0.5 - 1.5 v en2 operating mode 1.6 - - en/ct p in 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 circuit v out = v fb (1 + ) , v fb = 1.08 v , r2 = 5 k ~ 15 k v out (ovp) = v ovp (1 + ), v fb = 1.2 3 v, r4 = 5k ~ 15k ? function descriptions fb sense the regulated output voltage to complete the feedback loop, when v fb <0.4v, the scp is happened . sense1/2 the current limit sense pin, if v sense1 - v sense2 R 1 4 0mv, the over current is happened that it can turn - off driver cycle by cycle. c 2 0 . 1 u f d 1 b 2 4 0 a l 1 1 2 c 3 4 7 0 u f c 1 2 2 0 u f u 1 v c c s w f b e n / c t s e n s e 2 v o u t = 5 . 0 v / 1 a v i n = 1 0 ~ 3 0 v c 4 0 . 1 u f r 2 r 1 3 0 k r s e n s e v s s o v p c 6 0 . 1 u f c 5 s e n s e 1 r 4 r 3 a x 3 0 1 6 / a 0 . 1 r 3 n 9 f 7 . 5 k c 7 1 n f ? 2 r 1 r 4 r 3 r v?mw`r?y?b? w w w . g o f o t e c h . c o m
5/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 ovp the over voltage sense pin, if v ovp >1.23v, the ovp is happened that it can turn - off the driver. you can set v out ovp voltage by outside resistances (r 3 and r 4 ), please see below formula to set. en/ct the pin is enable/shutdown and auto restart control functions. when system is normal operating, this pin is enable/shutdown function. pulling this pin below a threshold voltage of under 0. 4 v shuts the regulator off, and pulling this pin from 0.5v to 1.5v turns the regulator on. however when v out is short (v fb <0.4v), the auto restart function can be started th at restart the regulator cycle by cycle. the 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. the charge - current is 30ua and discharge - current i s 1.3ua. 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. ) 4 r 3 r + 1 ( 23 . 1 = vout ) ovp ( v en / ct time t 1 t 2 time iin ( a ) 0 . 5 v 1 . 5 v 0 current limit ( ) .) ( . sec sec 1.3u 1 c6 = t2 30u 1 c6 = t1 v?mw`r?y?b? w w w . g o f o t e c h . c o m
6/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 ? application 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: v out = 1.08v (1+ ) table 1 resistor select for output voltage setting v out r2 r1 5.0v 7.5k 30k 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 driver can be turned off until the drop is small than 90 mv. the current limit set according to the following equation: the maximum output current table is shown as below; please refer the table to design. rsense () c urrent limit (a) 100m 1. 5 150m 0. 77 inductor selection for most designs, the different frequency can be reducing the inductor value; the AX3016 is suggested 100h to 120h for 50k frequencies. please refer the below table to design. l1 recommend valu e (v in =10 ~30 v ,v out = 5 v, i out = 1 a) version AX3016 l1 value (h) 100u~120u where is inductor ripple current. large value inductors lower ripple current and small value inductors result in high ripple currents. choose inductor ripple current approximately 2 0% of the maximum load current 1.2a, i l =0.24a. 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 (1.2a+0.12a). 2 r 1 r sense r 2 m ) 50 - 140 ( + m 140 = ) a ( it currentlim v?mw`r?y?b? w w w . g o f o t e c h . c o m
7/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 line compensation the function is designed i n order to compensate the output line loss, especially in heavy load. the AX3016/bs load regulation is positive; the v out voltage can be raised by output current. for example, v out =5v in i out =0a, when i out increase to 1a , the v out can be rise to about 5.2 5 v typically . 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 470f 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. the 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 i s the most important parameter. the esr can be calculated from the following formula. = 0.24a x 80m= 19.2mv 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 voltage ratings may be needed to provide the low esr values required for low output ripple voltage. system stability is depending on output capacitors esr, correct to choose output capacitors esr is very important. it is recommended to using a 220~470f, the esr values range is 40~130m . thermal considerations the sop - 8 l - ep package needs a heat sink under most conditions. the heat sink connect exposed pad of AX3016 to obtain best effect. the size of the heat sink depends on the input voltage, the output voltage , the load current and the ambient temperature. esr i v l ripple ? ? ? v?mw`r?y?b? w w w . g o f o t e c h . c o m
8/8 axelite confidential materials, do not copy or distribute without written consent . rev.1.0 dec.02, 2010 ax 3016 ? 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 v?mw`r?y?b? w w w . g o f o t e c h . c o m
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