ap2008 pwm buck controller this datasheet contains new product information. anachip corp. reserves the rights to modify the product specification without notice. no liability is assumed as a result of the use of this product. no rights under any patent accompany the sale of the product. rev. 0.3 feb 10, 2004 1/8 features - pwm buck control circuitry - operating voltage can be up to 20v - under voltage lockout (uvlo) protection - short circuit protection (scp) - soft-start circuit - variable oscillator frequency -- 300khz max - 0.77v voltage reference output - 8-pin pdip and sop packages applications - backlight inverter - lcd monitor - xdrom, xdsl product - dc/dc converters in computers, etc. general description the ap2008 integrates pulse-width-modulation (pwm) control circuit into a single chip, mainly designs for power-supply regulator. all the functions included an on-chip 0.77v reference output, an error amplifier, an adjusted oscillator, a soft-start, uvlo, scp circuitry, and a push-pull output circuit. switching frequency can be adjustable by trimming ct. during low vcc situation, the uvlo makes sure that the outputs are off until the internal circuit is operational normally. pin assignment 1 2 3 8 7 6 5 4 out gnd scp ss fb vcc ct comp ( top view ) pdip/sop pin descriptions name description ct timing capacitor fb voltage feedback ss soft-start. comp feedback loop compensation out pwm output gnd ground vcc supply voltage scp short circuit protection ordering information ap2008 x x x package packing s: sop-8l blank : tube a : taping lead free blank : normal l : lead free package n: pdip-8l
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 2/8 block diagram bandgap reference out pwm amplifier fb vcc scp ct error amplifier comp uvlo gnd 0.7v 1.5v + - 2.5v internal use 0.77v iss + - vcc oscillator 10k-300khz / ct value ss + + - absolute maximum ratings symbol parameter rating unit v cc supply voltage 22 v v i amplifier input voltage 20 v v o collector output voltage v cc -1.0v v i source source current 200 ma i sink sink current 200 ma t op operating temperature range -20 to +85 o c t st storage temperature range -65 to +150 o c t lead lead temperature 1.6 mm(1/16 inch) from case for 10 seconds 260 o c
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 3/8 recommended operating conditions symbol parameter min. max. unit v cc supply voltage 3.6 20 v v i amplifier input volt age 1.05 1.45 v v o collector output voltage vcc-1.5 v i fb current into feedback terminal 45 a r f feedback resistor 100 k ? c t timing capacitor 100 6800 pf f osc oscillator frequency 10 300 khz t op operating free-air temperature -20 85 oc electrical characteristics (t a =25oc, v cc =6v, f=200 khz) reference (ref) symbol parameter conditions min. typ. max. unit comp connect to fb 0.755 0.770 0.785 v t a = -20oc ~ 25oc -0.1 1 % v ref output voltage change with temperature t a = 25oc ~ 85oc -0.2 1 % under voltage lockout (uvlo) symbol parameter conditions min. typ. max. unit v ut upper threshold voltage (v cc ) 2.9 v v lw t lower threshold voltage (v cc ) 2.4 v v ht hysteresis (v cc ) i o(ref) = 0.1ma t a = 25oc 500 mv short-circuit protection (scp) control symbol parameter conditions min. typ. max. unit v it input threshold voltage t a = 25oc 0.60 0.67 0.75 v v stb standby voltage no pull up 100 130 160 mv v lt latched input voltage no pull up 50 100 mv i scp input (source) current v i = 0.7v, t a = 25oc -10 -15 -20 a v ct comparator threshold voltage (comp) 1.5 v oscillator (osc) symbol parameter conditions min. typ. max. unit f osc frequency c t =270 pf 200 khz standard deviation of frequency c t =270 pf 10 ? f osc frequency change with voltage v cc =3.6v ~ 20v 1 %
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 4/8 electrical characte ristics (continued) (t a =25oc, v cc =6v, f=200 khz) error-amplifier symbol parameter conditions min. typ. max. unit v io input offset voltage v o (fb)=0.77v 6 mv i io input offset current v o (fb)=0.77v 100 na i ib input bias current v o (fb)=0.77v 160 500 na v cm common-mode input voltage range v cc =3.6v ~ 20v 1.05 1.45 v av open-loop voltage amplification r f =200 k ? 70 80 db gbw unity-gain bandwidth 1.5 mhz cmrr common-mode rejection ratio 60 80 db v oh max. output voltage v ref -0.1 v v ol min. output voltage 1 v i oi output (sink) current (comp) v id = -0.1v, v o = 0.77v 0.5 1.6 ma i oo output (source) current (comp) v id = 0.1v, v o = 0.77v -45 -70 a output section symbol parameter conditions min. typ. max. unit i leak leakage current v o = 20v 10 a sink current v in = 12v 200 ma i drv source current v in = 12v 200 ma v sat output saturation voltage i o = 10 ma 1.0 1.5 v i sc short-circuit output current v o = 6v 120 ma pwm comparator symbol parameter conditions min. typ. max. unit v t0 ct=6800pf 0.6 0.7 v v t100 input threshold voltage at f = 10 khz (comp) maximum duty cycle 1.2 1.3 v total device symbol parameter conditions min. typ. max. unit i cca average supply current c t = 270pf 6 10 ma soft start symbol parameter conditions min. typ. max. unit v ss soft-start voltage 2.3 v i ss constant charge current 20 a
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 5/8 typical application circuit l1 10uh r1 r2 c3 470uf output step-down dc/dc converter c2 10nf (optional) vcc = 12v p mos q1 1 2 3 8 7 6 5 4 out fb vcc comp gnd scp ss ct c6 220nf c5 50nf c4 270pf 1k 4k c1 470uf 5a r3 30k c4 50nf (optional) 1v/5a typical characteristics reference output voltage v.s. power-supply voltage 0.755 0.76 0.765 0.77 0.775 0.78 0.785 4 6 8 10 12 14 16 18 20 vcc-power supply voltage (v) vref- reference output voltage (v) average supply current v.s. power-supply voltage 0 1 2 3 4 5 048121620 vcc - power-supply voltgae (v) icc-average supply current (ma) average supply current v.s. ambient temperatrue 2 3 4 5 6 7 -50 -25 0 25 50 75 100 t a - ambient temperatrure( ) i cc - average supply current (ma) v ct v.s. frequency 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 100 200 300 frequency (khz) v ct (v) vct(min) vct(max)
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 6/8 typical characteristics (continued) oscillator frequency v.s. timing capacitance 0 50 100 150 200 250 300 350 100 600 1100 1600 2100 2600 3100 3600 4100 4600 5100 5600 6100 6600 ct-timing capacitor (pf) fosc - frequency (khz) scp time-out period v.s. scp capacitance 0 5 10 15 20 25 30 35 45 90 135 180 225 270 315 360 405 450 495 cscp - scp capacitance (nf) tscp-scp time- out period (ms) soft-start time (ts) v.s. soft-start capacitor (css) 0 5 10 15 20 25 30 25 50 75 100 125 150 175 200 css (nf) ts (ms) marking information (top view) pdip/sop ac ap2008 yy ww x x logo part no. id code year: "01" =2001 "02" =2002 xth week: 01~52 ~ 5 8 4 1 blank: normal l: lead free package
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 7/8 package information (1) pdip-8l (plastic dual-in-line package ) e1 d 7 (4x) a l a2 a1 b2 b1 b e s 15 (4x) e c eb pin #1 indent o0.025 deep 0.006-0.008 inch e-pin o0.118 inch dimensions in millimeters dimensions in inches symbol min. nom. max. min. nom. max. a - - 5.33 - - 0.210 a1 0.38 - - 0.015 - - a2 3.1 3.30 3.5 0.122 0.130 0.138 b 0.36 0.46 0.56 0.014 0.018 0.022 b1 1.4 1.52 1.65 0.055 0.060 0.065 b2 0.81 0.99 1.14 0.032 0.039 0.045 c 0.20 0.25 0.36 0.008 0.010 0.014 d 9.02 9.27 9.53 0.355 0.365 0.375 e 7.62 7.94 8.26 0.300 0.313 0.325 e1 6.15 6.35 6.55 0.242 0.250 0.258 e - 2.54 - - 0.100 - l 2.92 3.3 3.81 0.115 0.130 0.150 eb 8.38 8.89 9.40 0.330 0.350 0.370 s 0.71 0.84 0.97 0.028 0.033 0.038
ap2008 pwm buck controller anachip corp. www.anachip.com.tw rev. 0.3 fe b 10, 2004 8/8 package information (continued) (2) sop- 8l(jedec small outline package) view "a" l c view "a" h e a a2 a1 b e d 7 (4x) 0.015x45 7 (4x) y dimensions in millimeters dimensions in inches symbol min. nom. max. min. nom. max. a 1.40 1.60 1.75 0.055 0.063 0.069 a1 0.10 - 0.25 0.040 - 0.100 a2 1.30 1.45 1.50 0.051 0.057 0.059 b 0.33 0.41 0.51 0.013 0.016 0.020 c 0.19 0.20 0.25 0.0075 0.008 0.010 d 4.80 5.05 5.30 0.189 0.199 0.209 e 3.70 3.90 4.10 0.146 0.154 0.161 e - 1.27 - - 0.050 - h 5.79 5.99 6.20 0.228 0.236 0.244 l 0.38 0.71 1.27 0.015 0.028 0.050 y - - 0.10 - - 0.004 0 o - 8 o 0 o - 8 o
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