1-800-634-3654 2.5v to 12v output MD1322F company name type no. lot no. 28 15 tab2 tab1 14 1 8.8 + 0.1 12.23 + 0.3 shindengen MD1322F 5 0 3 0 n pin assignment description the MD1322F is a high-efficiency step down dc-dc converter power integrated circuit with main mosfet switch and schottky barrier diode. the MD1322F can deliver 7.5 watts maximum (5v, 3.0a) with high efficiency over a wide input voltage range. this device has output voltage digitally selectable from 2.5v to 12v. with the MD1322F you can construct a complete dc-dc converter using only a few external components. featuring an hsop 28-pin surface mount package, the MD1322F allows you to incorporate a very small and thin power supply on your circuit board. vref 26 5 vcc vboot vb vg 6 23 22 tab2 tab1 vout 8-11 4.24 28 ocl- start up start=7.2v stop=6.7v boot reference vref=6.5v driver vref=vout+5.8v reference vref=5v5% tsd main switch mos off driver 100 ? c error amp pwm comp - - - + + + osc f=250khz 3v 1v clm vth= 0.1~0.2v v dd p. g n d gnd ocl+ s/s ampout amp- 27 3 1 2 2.45v 150 ? c r s q pin# symbol function description 1 2 3 4 5 6 7 8 ~ 11 12 ~ 21 22 23 24 25 26 27 28 tab1 tab2 s/s ocl- ocl+ gnd vcc vboot n/c p.gnd n/c vg vb gnd vts vref ampout amp- vout vdd capacitor for softstart overcurrent protection (ocl) (-) overcurrent protection (ocl) (+) signal gnd input voltage high side drive supply for main mos non-connection power gnd non-connection gate terminal of main mos bootstrap capacitor between vb and vout signal gnd output voltage selectable terminal internal voltage reference error amp out error amp (-) input power stage output drain of main mos switch vout:tab1 s/s: 1 ocl-: 2 ocl+: 3 gnd: 4 vcc: 5 vboot: 6 n/c: 7 tab2:v dd p.gnd: 8 p.gnd: 9 p.gnd: 10 p.gnd: 11 n/c: 12 n/c: 13 n/c: 14 28: amp- 27: ampout 26: vref: 25: vts 24: gnd 23: vb 22: vg 21: n/c 20: n/c 19: n/c 18: n/c 17: n/c 16: n/c 15: n/c vref - temperature compensated internal voltage. you can pull 1ma maximum for external circuit. osc - uses internal oscillator without external component. frequency (saw tooth wave form) is trimmed to 250khz on chip. error amp - error amp detects output voltage of dc-dc converter and controls pwm signal. you can adjust the loop gain when you connect feedback resistor and capacitor between ampout and amp (-). it will provide stable phase compensation. overcurrent protection - uses pulse-by-pulse current protection. current will be sensed voltage drop of external current sensing resistor. threshold of ocl is 0.19v. block diagram features high efficiency wide input voltage load range 8vdc to 30vdc up to 3adc output voltage selectable function 2.5v to 12v internal switching power device main mosfet for switch sbd for rectification fixed 250khz pwm frequency without external resistor and capacitor overcurrent protection thermal shutdown function free datasheet http:///
1-800-634-3654 2.5v-12v output MD1322F absolute maximum ratings (ta=25?) line voltage output mos input voltage output current (ave) output current (peak) ocl-,ocl+terminal voltage storage temperature junction temperature v in v dd i out ave i out peak v ocl tstg tj 32 32 3 4 5.5 -40 ~ 150 150 v v a a v ? ? electrical characteristics (ta=25?) parameter symbol conditions min typ max uni ts high side mos d - s voltage high side mos drain interruption current high side mos drain-source on resistance high side mos source-drain di forward voltage low side sbd peak reverse voltage low side sbd forward voltage low side sbd reverse current start voltage stop voltage stop-start voltage hysteresis current consumption boot terminal voltage internal reference voltage initial oscillation frequency overcurrent threshold voltage softstart terminal current error amplifier reference voltage overcurrent protection operating temperature vdss idss ron v sd v rm v f i r vcc_start vcc_stop vcc_hys icc vboot vref fosc vth_ocl i s / s vamp t_tsd 32 - - - 40 - - 6.5 6.0 - - 5.4 4.75 212.5 0.162 -20 2.4 - - - 140 - - - - 7.2 6.7 0.5 8 6.5 5 250 0.19 -12.5 2.45 150 - 10 250 1.5 - 0.55 2 7.9 7.4 - 10 7.6 5.25 287.5 0.218 -5 2.5 - v ua m ? v v v ma v v v ma v v khz v ua v ? i d =1ma, v gs =0v v ds =30v, v gs =0v i d =1.2a, v gs =4v i s =1.2a, v ds =0v - i f =1.2a v r =v rm - - - vcc=8v ~ 30v vcc=8v ~ 30v vcc=8v ~ 30v vcc=24v vcc=24v vcc=24v vcc=8v ~30v - parameter symbol rating units recommended operation conditions parameter recommendation units input voltage output voltage setting range operation temperature 8 ~ 30 2.5 ~ 12 -10 ~ 80 v v ? output current derating for 5.3v or higher output output setting voltage output current 2.5v ~5.3v 6v 8v 12v 3a 2.5v 2a 1.5a < = < = < = free datasheet http:///
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