march 2002 1 MIC2194 MIC2194 micrel MIC2194 400khz so-8 buck control ic final information general description micrel? MIC2194 is a high efficiency pwm buck control ic housed in the so-8 package. its 2.9v to 14v input voltage range allows it to efficiently step down voltages in 3.3v, 5v, and 12v systems as well as 1- or 2-cell li ion battery powered applications. the flexible architecture of the MIC2194 allows for it to be configured as a buck or a buck-boost converter. the MIC2194 solution saves valuable board space. the device is housed in the space-saving so-8 package, whose low pin-count minimizes external components. its 400khz pwm operation allows a small inductor and small output capacitors to be used. the MIC2194 can implement all- ceramic capacitor solutions. the MIC2194 drives a high-side p-channel mosfet. a low output driver impedance of 2 ? allows the MIC2194 to drive large external mosfets to generate a wide range of output currents. the MIC2194 can achieve maximum duty cycles of 100%, which can be useful in low headroom applications. the MIC2194 is available in an 8 pin soic package with a junction temperature range of ?0 c to +125 c. typical application v in 12v 47 f 20v ( 2) si4431a ( 2) b530 10k 3.32k 220 f 10v ( 2) 5.2 h 2k 0.012 ? 2.2nf MIC2194bm vin en/ uvlo cs outp comp vdd fb gnd v out 5v, 5a 1 f adjustable output buck converter v in +3.3v 10 f 16v si9803 b530 3.01k 1k 220 f 10v ( 2) 22 h 4.99k 0.040 ? 10nf MIC2194bm vin en/ uvlo cs outp comp vdd fb gnd v out 5v, 0.6a 1 f 10 f 16v 22nf positive-to-negative buck-boost converter features 2.9v to 14v input voltage range 400khz oscillator frequency pwm current mode control 2 ? output drivers 100% maximum duty cycle 0.5 a micro-power shutdown programmable uvlo front edge blanking cycle-by-cycle current limiting frequency foldback short circuit protection 8-lead soic package applications point of load power supplies negative voltage buck-boost power supplies distributed power systems base stations wireless modems adsl line cards servers step down conversion in 3.3v, 5v, 12v systems 1-and 2-cell li ion battery operated equipment micrel, inc. ?1849 fortune drive ?san jose, ca 95131 ?usa ?tel + 1 (408) 944-0800 ?fax + 1 (408) 944-0970 ?http://www.mic rel.com
MIC2194 micrel MIC2194 2 march 2002 pin configuration 1 comp fb en/uvlo cs 8 vin outp gnd vdd 7 6 5 2 3 4 8 lead soic (m) ordering information part number output voltage frequency junction temp. range package MIC2194bm adjustable 400khz 40 c to +125 c 8-lead sop pin description pin number pin name pin function 1 comp compensation (output): internal error amplifier output. connect to a capacitor or series rc network to compensate the regulator s control loop. 2 fb feedback (input): the circuit regulates this pin to 1.245v. 3 en/uvlo enable/undervoltage lockout (input): a low level on this pin will power down the device, reducing the quiescent current to under 0.5 a. this pin has two separate thresholds, below 1.5v the output switching is disabled, and below 0.9v the device is forced into a complete micropower shutdown. the 1.5v threshold functions as an accurate undervoltage lockout (uvlo) with hysteresis. 4 cs the ( ) input to the current limit comparator. a built-in offset of 110mv between vin and csl in conjunction with the current sense resistor sets the current limit threshold level. this is also the ( ) input to the current amplifier. 5 vdd 3v internal linear-regulator output. vdd is also the supply voltage bus for the chip. bypass to gnd with 1 f. 6 gnd ground 7 outp high current drive for the synchronous n-channel mosfet. voltage swing is from ground to vin. on-resistance is typically 3 ? @ 5v in . 8 vin input voltage to the circuit. also the high side input to the current sense amplifier supplies power to the gate drive circuit.
march 2002 3 MIC2194 MIC2194 micrel electrical characteristics v in = 5v, v out = 3.3v, t j = 25 c, unless otherwise specified. bold values indicate 40 c |