MIC4574YN Microchip

MIC4574 Micrel, Inc. MIC4574 200kHz Simple 0.5A Buck Regulator General Description Features The MIC4574 is a series of easy to use fixed and adjustable Fixed 200kHz operation BiCMOS step-down (buck) switch-mode voltage regulators. 3.3V, 5V, and adjustable output versions The 200kHz MIC4574 duplicates the pinout and function of Voltage over specified line and load conditions: the 52kHz LM2574. The higher switching frequency may Fixed version: 3% max. output voltage allow up to a 2:1 reduction in output filter inductor size. Adjustable version: 2% max. feedback voltage Guaranteed 0.5A switch current The MIC4574 is available in 3.3V, and 5V fixed output Wide 4V to 24V input voltage range versions or a 1.23V to 20V adjustable output version. Both Wide 1.23V to 20V output voltage range versions are capable of driving a 0.5A 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% efficiency (adjustable version > 75% typ.) adjustable versions, and the output voltage is guaranteed to Standard inductors and capacitors are 3% for fixed versions, within specified voltages and load 25% of typical LM2574 values conditions. The oscillator frequency is guaranteed to 10%. Thermal shutdown In shutdown mode, the regulator draws less than 200A Overcurrent protection standby current. The regulator performs cycle-by-cycle cur- 100% electrical thermal limit burn-in rent limiting and thermal shutdown for protection under fault Applications conditions. Simple high-efficiency step-down (buck) regulator This series of simple switch-mode regulators requires a Efficient preregulator for linear regulators minimum number of external components and can operate On-card switching regulators using a standard series of inductors. Frequency compensa- Positive-to-negative converter (inverting buck-boost) tion is provided internally. Isolated flyback converter using minimum external The MIC4574 is available in the DIP (N) package and is rated components over the industrial temperature range. Negative boost converter Data sheets and support documentation can be found on Micrels web site at www.micrel.com. Typical Application L1 5.0V/0.5A Shutdown 3 7 SHDN SW Enable 100H MIC4574-5.0BN 8V to 24V 5 1 C2 V FB IN 220F C1 SGND PGND 16V D1 47F 24 1N5819 35V Fixed Regulator Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC4574 Micrel, Inc. Ordering Information Part Number Temperature Standard Pb-Free Voltage Range Package MIC4574-3.3BN MIC4574-3.3YN 3.3V 40C to +85C 8-pin DIP MIC4574-5.0BN MIC4574-5.0YN 5.0V 40C to +85C 8-pin DIP MIC4574BN MIC4574YN Adjustable 40C to +85C 8-pin DIP Pin Configuration FB 1 8 NC SGND 2 7 SW SHDN 3 6 NC PGND 4 5 V IN 8-Pin DIP (N) Pin Description Pin Number Pin Name Pin Function 1FB Feedback (Input): Output voltage feedback to regulator. Connect to output of supply for fixed versions. Connect to 1.23V tap of resistive divider for adjustable versions. 2 SGND Signal Ground. 3 SHDN Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts down regulator. 4 PGND Power Ground. 5 VIN Supply Voltage (Input): Unregulated +4V to +24V supply voltage. 7SW Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Shottky diode. 6, 8 NC Not internally connected. Solder to printed circuit for maximum heat transfer. M9999-062105 2 June 2005