aic1401 p wm step-down switching controller w ith shutdown analog integrations corporation 4f, 9, industry e. 9th rd, science based industrial park, hsinchu taiwan, roc www.analog.com.tw ds-1 401 - 00 may 24, 01 tel: 886-3-5772500 fax: 886-3-57 72510 1 n features l operation voltage up to 15v l voltage-mode operation l fast transient response l built in accurate 1.3v voltage reference l adjustable over current protection using r ds ( on ) no external current sense resi s tor required l low shutdown current l 200khz free-running oscillator l built in soft start. n applications l notebook pc l advanced pc mboards l information pc s l servers and workstations l pc add-on cards n description the aic1401 is a high efficiency, pwm step- down, voltage-mode, switching controller. it is suitable for ia, notebook, lcd pc and lcd monitor main power applications. the built-in high voltage cmos driver drives an external n-channel mosfet for replacing the higher cost p-channel mosfet in a standard buck topology. the 200khz switching frequency allows using smaller external components while maintaining high conversion efficiency. the 11mhz bandwidth and 6v/us slew rate of the error amplifier ensures the higher converter bandwidth and the fast transient response. the aic1401 also features over current protection. it provides adjustable over current trigger point and short-circuit protections by sensing the output current across the on resistance of the external n-channel mosfet rather then an expensive external low value sense resistor. n ordering information order number AIC1401CS (sop8) pin configuration top view lx 1 3 4 2 vcc /sh d n comp fb ug gnd 8 6 5 7 ocset package type s: small outline temperature range c: 0 c ~+70 c aic1401- x x
aic1401 2 n typical application circuit aic1401 *c1 1 m f c5 33p c6 1000p c2 1000p + c4 330 m fx3 + c3 470 m f r4 13k r3 2k r6 5k r2 90.9k r5 10 r1 2.2k l2 7 m h l1 1.5 m h d1 sra1620 m1 ir3303 1.5v/5a *c1 must be very close to vcc pin v out 5v 12v ocset /shdn comp fb vcc ug lx gnd dc/dc converter n absolute maximum ratings supply voltage, v cc ....?...???............................????......................................... 15v input, output, or i/o voltage ...............??????....??......... gnd - 0.3v to vcc+0.3v esd classification .............................????.....??..............??......................... class 2 recommended operating conditions supply voltage, v cc ....?......................????.......???.................................. 12v 10% ambient temperature range .?................................????.???.................. 0 c~70 c junction temperature range ....?............???.........?..??......................... 0 c~ 100 c thermal information thermal resistance, q ja (typical, note 1) soic package ...............................?????????..?????........?. 100 c/w soic package (with 3 in 2 of copper) ??????????????......?.. 90 c/w maximum junction temperature (plastic package) ???.??..???................... 150 c maximum storage temperature range ????..????......??.?......... ?65 c~150 c maximum lead temperature (soldering 10 sec) ???????...??......?......... 300 c note 1: q ja is measured with the component mounted on an evaluation pc board in free air. n test circuit refer to typical application circuit.
aic1401 3 n electrical characteristics (vcc= 12v, ta=25 c, unless otherwise specified.) parameter test conditions symbol min. typ. max. unit vcc supply current nominal supply ugate open i vcc 2 ma power-on reset v cc threshold v ocset =4.5v 9.5 v oscillator frequency 200 khz duty cycle 88 % internal reference voltage reference voltage 1.27 1.3 0 1.33 v error amplifier dc gain 76 db gain-bandwidth product gbw 11 mhz slew rate sr 6 v/ m s gate driver upper gate source r ugate 7 w upper gate sink r ugate 5 w protection ocset current source v ocset =4.5vdc i ocset 200 m a ss current i ss 10 m a shutdown shutdown low input v in l 0.35 v shutdown high input v in h 2 v shutdown mode current 1 m a
aic1401 4 n pin descriptions pin 1: ocset - current limit sense pin. connect a resistor r ocset from this pin to the drain of the external mosfet. r ocset , an internal 200 m a current source (i ocset ), and the external mosfet on- resistance ( r ds( on) ) jointly set the overcurrent trip point according to the following equation: i i r r peak ocset ocset ds( on = ) if fb pin voltage is sensed to be below 50% of the internal voltage reference, the overcurrent comparator cycles the soft-start function. pin 2: /shdn - shutdown pin. connect this pin to ground for shutdown. pin 3: comp - external compensation pin. this pin is connected to error amplifier output and pwm comparator. a rc network is connected to fb pin to compensate the voltage-control feedback loop of the converter. pin 4: fb - the error amplifier inverting input pin. the fb pin and comp pin are used to compensate the voltage-control feedback loop. pin 5: gnd - ground pin. pin 6: lx - overcurrent detection pin. connect the lx pin to source of the external n-mosfet. this pin detects the voltage drop across the mosfet r ds( on) for overcurrent protection. pin 7: ug - external mosfet gate drive pin. connect this pin to gate of the external mosfet. pin 8: vcc - the chip power supply pin. recommended supply voltage is 12v. n application circuit refer to typical application circuit
aic1401 5 ?? physical dimensions l 8 lead plastic so (unit: mm) symbol min max a 1.35 1.75 a1 0.10 0.25 b 0.33 0.51 c 0.19 0.25 d 4.80 5.00 e 3.80 4.00 e 1.27(typ) h 5.80 6.20 l 0.40 1.27 d h e a b a1 c e l
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