MIC4576WU-TR Microchip

MIC4576 Micrel, Inc. MIC4576 200kHz Simple 3A Buck Regulator General Description Features The MIC4576 is a series of easy to use xed and adjustable Fixed 200kHz operation BiCMOS step-down (buck) switch-mode voltage regulators. 3.3V, 5V, and adjustable output versions The 200kHz MIC4576 duplicates the pinout and function of Voltage over specied line and load conditions: the 52kHz LM2576. The higher switching frequency may Fixed version: 3% max. output voltage allow up to a 2:1 reduction in output lter inductor size. Adjustable version: 2% max. feedback voltage Guaranteed 3A switch current The MIC4576 is available in 3.3V, and 5V xed output ver- Wide 4V to 36V input voltage range sions or a 1.23V to 33V adjustable output version. Both Wide 1.23V to 33V output voltage range versions are capable of driving a 3A load with excellent line Requires minimum external components and load regulation. < 200A typical shutdown mode The feedback voltage is guaranteed to 2% tolerance for 75% efciency (adjustable version > 75% typical) adjustable versions, and the output voltage is guaranteed to Standard inductors are 25% of typical LM2576 values 3% for xed versions, within specied voltages and load con- Thermal shutdown ditions. The oscillator frequency is guaranteed to 10%. Overcurrent protection In shutdown mode, the regulator draws less than 200A 100% electrical thermal limit burn-in standby current. The regulator performs cycle-by-cycle Applications current limiting and thermal shutdown for protection under fault conditions. Simple high-efciency step-down (buck) regulator Efcient preregulator for linear regulators This series of simple switch-mode regulators requires a mini- On-card switching regulators mum number of external components and can operate using Positive-to-negative converter (inverting buck-boost) a standard series of inductors. Frequency compensation is Battery Charger provided internally. Negative boost converter The MIC4576 is available in TO-220 (T) and TO-263 (U) Step-down to 3.3V for Intel Pentium packages for the industrial temperature range. and similar microprocessors Typical Applications L1 5V/3A 5 2 Shutdown SHDN SW Enable 33H MIC4576-5.0WT 8V to 36V 1 4 C2 V FB IN 1000F C1 GND 16V D1 470F 3 MBR360 63V Fixed Regulator L1 12V/3A 5 2 Shutdown SHDN SW Enable 68H R2 MIC4576WT 13.0k 16V to 36V 4 1 C2 1% V FB IN 1000F C1 GND R1 16V 470F MBR360 1.50k 3 63V 1% Adjustable Regulator Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC4576 Micrel, Inc. Ordering Information Standard RoHS Compliant Part Number Part Number* Voltage Temperature Range Package MIC4576-3.3BT MIC4576-3.3WT 3.3V 40C to +85C TO-220-5 MIC4576-5.0BT MIC4576-5.0WT 5.0V 40C to +85C TO-220-5 MIC4576BT MIC4576WT ADJ. 40C to +85C TO-220-5 MIC4576-3.3BU MIC4576-3.3WU 3.3V 40C to +85C TO-263-5 MIC4576-5.0BU MIC4576-5.0WU 5.0V 40C to +85C TO-263-5 MIC4576BU MIC4576WU ADJ. 40C to +85C TO-263-5 * RoHS compliant withhigh-melting solde exemption. Pin Conguration 5 SHDN 4 FB 3 GND 2 SW 1 V IN 5-Pin TO-220 (T) 5 SHDN 4 FB 3 GND 2 SW 1 V IN 5-Pin TO-263 (U) Pin Description Pin Number Pin Name Pin Function 1 V Supply Voltage (Input): Unregulated +4V to +36V supply voltage. IN 2 SW Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Shottky diode. 3, TAB GND Ground 4 FB Feedback (Input): Output voltage feedback to regulator. Connect to output of supply for xed versions. Connect to 1.23V tap of resistive divider for adjustable versions. 5 SHDN Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts down regulator. MIC4576 2 March 2006 TAB TAB