MIC4681 Micrel MIC4681 2A-Peak SuperSwitcher SOP-8 Buck Regulator General Description Features The MIC4681 SuperSwitcher is an easy-to-use step-down SO-8 package with over 1A continuous output current (buck) voltage-mode switching regulator. The 200kHz Capable of 2A pulse charging for GSM applications MIC4681 achieves over 1A of continuous output current over All surface mount solution a 4V to 30V input range in an 8-lead SOPpackage . The Only 4 external components required MIC4681 features a high 2.1A minimum current limit, making Fixed 200kHz operation the device ideal for pulsed current applications such as GSM Output adjustable down to 1.25V and TDMA cell phone battery chargers and power supplies. Internally compensated with fast transient response The MIC4681 sustains an output of 4.2V/2A within a typical Wide 4V to 30V operating input voltage range GSM charging environment. Less than 6 A typical shutdown-mode current Up to 90% efficiency The MIC4681 has an input voltage range of 4V to 30V, with Thermal shutdown excellent line, load, and transient response. The regulator Overcurrent protection performs cycle-by-cycle current limiting and thermal shut- down for protection under fault conditions. In shutdown mode, the regulator draws less than 6 A of standby current. Applications The MIC4681 SuperSwitcher regulator requires a mini- Cellular phone battery charger mum number of external components and can operate using Cellular phone power supply a standard series of inductors and capacitors. Frequency Simple 1A continuous high-efficiency step-down (buck) compensation is provided internally for fast transient re- regulator sponse and ease of use. Replacement of a TO-220 and TO-263 designs The MIC4681 is available in the 8-lead SOP with a Positive-to-negative converter (inverting buck-boost) 40C to +125C junction temperature range. Negative boost converter Higher output current regulator using external FET Typical Applications MIC4681BM L1 +5V to +30V 2.5V/1A 2 3 IN SW C1 68 H R1 22 F C2 3.01k 35V 220 F SHUTDOWN 1 4 SHDN FB ENABLE 10V D1 R2 GND B340A or Power 2.94k 58 SS36 SOP-8 Adjustable Regulator Circuit SuperSwitcher is a trademark of Micrel, Inc. Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC4681 Micrel Ordering Information Part Number Standard Lead-Free Voltage Frequency Junction Temp. Range Package MIC4681BM MIC4681YM Adjustable 400kHz 40C to +125C 8-lead SOP Pin Configuration SHDN 1 8 GND VIN 2 7 GND SW 3 6 GND FB 4 5 GND SOP-8 (M) Pin Description Pin Number Pin Name Pin Function 1 SHDN Shutdown (Input): Logic low enables regulator. Logic high (>2V) shuts down regulator. 2 VIN Supply Voltage (Input): Unregulated +4V to +30V supply voltage. 3 SW Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Shottky diode. 4 FB Feedback (Input): Connect to 1.23V-tap of voltage-divider network 58 GND Ground MIC4681 2 April 2005