ap2008 pwm buck controller ap2008 rev. 2 1 of 8 february 2009 www.diodes.com ? diodes incorporated lead-free ? 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 sop package ? sop-8l: available in ?green? molding compound (no br, sb) ? lead free finish/ rohs compliant (note 1) the ap2008 integrates pulse-width-modulation (pwm) control circuit into a single chip, mainly designs for power-supply regulator. all the functions include an on-chip 0.77v reference output, an error amplifier, an adjustable oscillator, a soft-start, uvlo, scp circuitry, and a push-pull output circuit. switching frequency is adjustable by trimming ct. during low vcc situation, the uvlo makes sure that the outputs are off until the internal circuit is operational normally. applications ? backlight inverter ? lcd monitor ? xdrom, xdsl product ? dc/dc converters in computers, etc. ordering information ap 2008 s x - 13 package packing lead free 13 : tape & reel g : green s : sop-8l l : lead free device package code packaging (note 2) 13? tape and reel quantity part number suffix ap2008sl-13 s sop-8l 2500/tape & reel -13 ap2008sg-13 s sop-8l 2500/tape & reel -13 notes: 1. eu directive 2002/95/ec (rohs). all applicable rohs exemptions applied. please visit our website at http://www.diodes.com/products/lead_free.html . 2. pad layout as shown on diodes inc. suggested pad layout document ap02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf . features general description
ap2008 pwm buck controller ap2008 rev. 2 2 of 8 february 2009 www.diodes.com ? diodes incorporated pin assignments 1 2 3 4 8 7 6 5 out ss comp scp vcc gnd ct fb ( top view ) sop-8l pin descriptions pin name description out pwm output vcc supply voltage comp feedback loop compensation fb voltage feedback scp short circuit protection ss soft-start. ct timing capacitor gnd ground
ap2008 pwm buck controller ap2008 rev. 2 3 of 8 february 2009 www.diodes.com ? diodes incorporated 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 maxi mum 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 recommended oper ating conditions symbol parameter min max unit v cc supply voltage 3.6 20 v v i amplifier input voltage 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
ap2008 pwm buck controller ap2008 rev. 2 4 of 8 february 2009 www.diodes.com ? diodes incorporated electrical characteristics (t a =25oc, v cc =6v, f=200 khz) reference (ref) symbol parameter conditions min typ. max unit v ref comp connect to fb 0.755 0.770 0.785 v output voltage change with temperature t a = -20oc ~ 25oc -0.1 1 % 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 ) i o(ref) = 0.1ma t a = 25oc 2.9 v v lwt lower threshold voltage (v cc ) 2.4 v v ht hysteresis (v cc ) 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 f osc standard deviation of frequency c t =270 pf 10 % frequency change with voltage v cc =3.6v ~ 20v 1 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
ap2008 pwm buck controller ap2008 rev. 2 5 of 8 february 2009 www.diodes.com ? diodes incorporated electrical characteristics (continued) (t a =25oc, v cc =6v, f=200 khz) output section symbol parameter conditions min typ. max unit i leak leakage current v o = 20v 10 a i drv sink current v in = 12v 200 ma 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 input threshold voltage at f = 10 khz (comp) ct=6800pf 0.6 0.7 v v t100 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 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
ap2008 pwm buck controller ap2008 rev. 2 6 of 8 february 2009 www.diodes.com ? diodes incorporated typical characteristics reference output voltage vs. power-supply voltage 0.755 0.76 0.765 0.77 0.775 0.78 0.785 4 6 8 101214161820 vcc-power supply voltage (v) vref- reference output voltage (v) a verage supply current vs. power-supply voltage 0 1 2 3 4 5 048121620 vcc - power-supply voltgae (v) icc-average supply current (ma) average supply current vs. ambient temperature 2 3 4 5 6 7 -50 -25 0 25 50 75 100 t a - ambient temperature ( ) i cc - average supply current (ma) v ct vs. 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) oscillator frequency vs. 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 vs. 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)
ap2008 pwm buck controller ap2008 rev. 2 7 of 8 february 2009 www.diodes.com ? diodes incorporated typical characteristics (continued) soft-start time (ts) vs. soft-start capacitor (css) 0 5 10 15 20 25 30 25 50 75 100 125 150 175 200 css (nf) ts (ms) (1) sop-8l ( top view ) ap2008 yy ww x x logo part number 5 8 4 1 ww : week : 01~52; 52 yy : year : 08, 09,10~ g : green x : internal code represents 52 and 53 week l : lead free marking information
ap2008 pwm buck controller ap2008 rev. 2 8 of 8 february 2009 www.diodes.com ? diodes incorporated package information (all dimensions in mm) (1) package type: sop- 8l 1.27typ 0.3/0.5 7~9 4.85/4.95 3.85/3.95 5.90/6.10 0.15/0.25 7~9 0.62/0.82 0.10/0.20 gauge plane 0.254 seating plane 0.35max. 45 detail "a" detail "a" 1.30/1.50 1.75max. land pattern recommendation (unit: mm) 6x-1.27 8x-1.55 8x-0.60 5.4 0/8 important notice life support diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or ot her changes without further notice to any product herein. diodes incorporated does not assume any liability arising out of the application or use of any pr oduct described herein; neither does it convey any license under its patent rights, nor the rights of others. the user of products in such applications shall assume all risks of such use and will agree to hold diodes incorporated and all the companies whose products are represented on our website, harmless against all dam ages. diodes incorporated products are not authorized for use as critical components in life support devices or systems without the e xpressed written approval of the president of diodes incorporated.
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