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1/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 1. 9 a fixed frequency white led driver ? general description the AX2012 is a step - up conver ter designed for driving up to 8 series white leds for backlighting application . the AX2012 uses current mode, 1.2mh z fixed frequency architecture to regulate the led current, which is set through an external current sense resistor. its low 300 mv feedback voltage reduces power loss and improves efficiency. the ov pin monitors the output voltage and turns off the converter if an over - voltage condition is present due to a n open circuit condition. the AX2012 includes under - voltage lockout, current limiting and thermal shutdown protection preventing damage in the event of an output overload. the driver is available in small 6 - pin tsot - 23 and 8 - pin tdfn (2mm x 2mm) packages. ? f eatures - 2. 5 v to 5.5 v operating input voltage range - drives up to 8 series white leds - 1. 2m hz fixed switching frequency - wide range for pwm dimming (200hz to 200khz) - i nternal 1. 9 a switching current limit - over voltage protection (ovp) - internal soft - start func tion - c urrent limit and thermal shutdown protect ion - under voltage lockout - available in the 6 -pin tsot- 23 and 8 - pin tdfn package s v?mw`r?y?b? www.gofotech.com
2/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? b lock d iagram ? pin assignment the package s of AX2012 are tsot23 - 6l and tdfn - 8 l ; the pin assignme nt is given by : name description gnd ground p in vcc power i nput p in ov ovp s ense p in en enable with d imming p in ; i nternal p ull - l ow ; l ogic h igh a ctive fb feedback p in ; p ut a r esistor to gnd to s etting the c urrent nc no c onnect p in sw sw itch o utput p in v cc lx control and driver logic en reference 1 . 238 v soft start current sense slope compensation oscillator 1 . 2 mhz fb error amplifier summing comparator thermal shutdown enable logic gnd n - mos 10 ms 300 mv shutdown ovp ov uvlo tdfn - 8 l ( 2 * 2 ) 1 2 3 4 5 6 7 8 gnd sw ( gnd ) nc fb gnd vcc ov en ( t o p v i e w ) t s o t - 2 3 - 6 l 3 2 6 4 1 g n d v c c s w o v 5 f b e n v?mw`r?y?b? www.gofotech.com
3/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? order/marking information order information top marking ( tsot - 23 - 6l ) top marking ( tdfn - 8l ) ? absolute maximum ratings (at t a =25c) characteristics symbol rating unit v cc pin voltage v cc gnd - 0.3 to gnd + 6 v en , f b , ov pin voltage gnd - 0.3 to v cc + 0.3 v sw , ov pin voltage v sw 30 v power dissipation pd ( t j - t a ) / ja mw storage temperature range t st - 65 to +150 c operating junction temperature range t op - 40 to + 125 c thermal resistance from junction to case tsot - 23 - 6l jc 180 c /w tdfn - 8 l 25 thermal resistance from junction to ambient tsot - 23 - 6l ja 250 c / w tdfn - 8 l 120 note: ja is measured with the pcb copper area of approximately 1 in 2 (multi - layer). a x 2 0 1 2 x x x p a c k a g e t y p e p a c k i n g b l a n k : b a g a : t a p i n g c t : t s o t - 2 3 - 6 l z 8 : t d f n - 8 l ( 2 * 2 ) j a x 2 0 1 2 w e e k : 0 1 ~ 2 6 ( a ~ z ) 2 7 ~ 5 2 ( a ~ z ) y e a r : a = 2 0 1 0 1 = 2 0 1 1 i d c o d e : i n t e r n a l a y w x a x 2 0 1 2 y e a r : a = 2 0 1 0 1 = 2 0 1 1 w e e k : 0 1 ~ 2 6 ( a ~ z ) 2 7 ~ 5 2 ( a ~ z ) i d c o d e : i n t e r n a l y w x j a v?mw`r?y?b? www.gofotech.com
4/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? electrical characterustics ( v cc =5 v, i out = 20ma , t a = 25c , unless otherwise noted) characteristics symbol conditions min typ max units input voltag e r ange v cc 2. 5 - 5.5 v step - up voltage range v out 3 - 27 v ov sense voltage v ov 27.5 29 30.5 v under voltage lockout u vlo rising - 2.25 2.4 5 v uvlo hysteresis - 1 00 - m v feedback voltage v fb 285 300 315 mv en threshold logic - high voltage v ih 1.4 - - v logic - low voltage v il - - 0.4 v en hysteresis - 2 00 - m v operating q uiescent c urrent i ccq i o ut = 0ma, v fb = 0 .5v - 170 - a shutdown c urrent i sd v en =0v , t en > 20ms - - 1 a n - c hannel mosfet c urrent l imit (note1) i lim duty=50% - 1.9 - a mosfet o n - r esistance (note1) r ds(on) v cc =3v, i sw =1a - 0.6 - v cc =5v, i sw =1a - 0.45 - maximum duty cycle d max 85 90 - % line regula tion v cc = 3 v to 5v - 1 - % switching f requency f osc 0.9 1 . 2 1 . 5 m hz dimming clock rate f dim 0.2 - 200 khz fb input leakage current i fb - lkg v fb = 0.5v - 0 .01 100 n a sw leakage current i swl v s w = 27v, v fb =0.5v - - 1 a en i nput l eakage c urrent i en - lkg 1 v en = v cc - 1.5 3 a i en - lkg 2 v en = gnd - 0.01 0.1 a shutdown delay t shdn - 10 - ms thermal shutdown t sd - 150 - c thermal shutdown hysteresis t sh - 30 - note1: guaranteed by design. v?mw`r?y?b? www.gofotech.com
5/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? a pplication c ircuit (1) 8 series led application (2) led dimming application vin = 5 v c 1 4 . 7 uf l 1 4 . 7 uh u 1 ax 2012 4 6 5 1 vcc en ov gnd sw c 2 1 uf d 1 b 240 a i led = v fb / r 3 , v fb = 300 mv on off 2 fb r 3 3 8 - wleds vin = 5 v c 1 4 . 7 uf l 1 4 . 7 uh u 1 ax 2012 4 6 5 1 vcc en ov gnd sw c 2 1 uf d 1 b 240 a i led = v fb / r 3 , v fb = 300 mv 200 ~ 200 khz 2 fb r 3 3 8 - wleds dimming v?mw`r?y?b? www.gofotech.com
6/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? a pplication i nformation setting the i led current application circuit item shows the basic application circuit with ax 2012 adjustable output version. the external resistor sets the led output current according to the following equation: i led r 3 20ma 15 6 mw 350ma 0.857 105 mw over voltage protection ov measure the output voltage for open circuit protection. connect ov pin to the output at the top of the led string. if v out above 29v, the ovp protection is happened that stops the internal driver unti l v out below 29v. 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 ( 2.25 v-100mv). input capacitor selection the input capacitor reduces the surge current drawn from the input and switching noise from the device. the input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the inp ut. a low esr input capacitor sized for maximum rms current must be used. ceramic capacitors with x5r or x7r dielectrics are highly recommended because of their low esr and small tempe rature coefficients. a 4.7 f ceramic capacitor for most applications is sufficient. for a lower output power requirement application, this value can be decreased. output capacitor selection the output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. the output capacitor m ust have low impedance at the switching frequency. ceramic capacitors with x5r or x7r dielectrics are recommended due to their low esr and high ripple current. a 1uf ceramic capacitors works for most of the applications. higher capacitor values can be used to improve the load transient response. ) r3 300mv ( = i led v?mw`r?y?b? www.gofotech.com
7/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? typical characteristics efficiency vs. output current efficiency vs. input voltage output voltage vs. output current quiescent current vs. input voltage frequency vs. input voltage frequency vs. temperature v?mw`r?y?b? www.gofotech.com
8/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? typical characteristics (continuous) reference voltage vs. input voltage reference voltage vs. temperature led current vs. duty enable threshold vs. input voltage v?mw`r?y?b? www.gofotech.com
9/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? typical characteristics (continuous) power on from v in power on from en steady s tate operation normal operation into ovp pwm dimming from en (200hz) pwm dimming from en (20khz) v in v sw v out i out en v sw v out i out v in =5v 4wleds i out =150ma v in =5v , 4wleds , i out =150ma v sw v fb v out i out v in v sw v out i out ( v out , i out : measured by ac coupled mode ) v in =5v , 3 wleds , i out =150ma v e n v sw v out i out v e n v sw v out i out v in =5v , 4 wleds , i out =150ma v in =5v , 4 wleds , i out =150ma v in =5v 4wleds i out =150ma v?mw`r?y?b? www.gofotech.com
10/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 ? p ackage o utlines (1) tsot - 23- 6 l 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 0.14 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 jedec outline: mo-193 aa e 1 e e e 1 b d a a 1 a 2 y l 1 r l c l 2 v?mw`r?y?b? www.gofotech.com
11/ 11 axelite confidential materials, do not copy or distribute without written consent. rev.1.1 nov. 05 , 20 10 ax 2012 (2) tdfn - 8l (2*2 0.75mm) symbol dimensions i n millimeters dimensions i n inches min. nom. max. min. nom. max. a 0.70 0.75 0.80 0.028 0.030 0.031 a1 0.00 0.02 0.05 0 0.001 0.002 b 0.15 0.20 0.25 0.006 0.008 0.010 c 0.19 0.20 0.25 0.007 0.008 0.010 d 1.90 2.00 2.10 0.075 0.079 0.082 d2 1.55 1.60 1.65 0.061 0.063 0.065 e 1.90 2.00 2.10 0.075 0.079 0.082 e2 0.85 0.90 0.95 0.033 0.035 0.037 e - 0.50 - - 0.020 - l 0 .30 0.35 0.40 0.012 0.014 0.016 y 0.00 - 0.075 0 - 0.003 1 d 2 1 e 2 l b e 1 e 1 d p i n 1 i n d e n t c a 1 y v?mw`r?y?b? www.gofotech.com

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