MIC4685 3A SPAK SuperSwitcher Buck Regulator General Description Features The MIC4685 is a high-efficiency 200kHz stepdown (buck) Low 2mm prole SPAK package switching regulator. Power conversion efficiency of above 3A continuous output current 85% is easily obtainable for a wide variety of applications. Wide 4V to 30V input voltage range (34V transient) The MIC4685 achieves 3A of continuous current in the Fixed 200kHz PWM operation 7-pin SPAK package. Over 85% efciency The thermal performance of the SPAK allows it to replace 2 TO-220s and TO-263s (D PAKs) in many applications. Output voltage adjustable to 1.235V The SPAK saves board space with a 36% smaller footprint All surface mount solution than TO-263. Internally compensated with fast transient response High-efciency is maintained over a wide output current Over-current protection range by utilizing a boost capacitor to increase the voltage Frequency foldback short-circuit protection available to saturate the internal power switch. As a result Thermal shutdown of this high-efciency, only the ground plane of the PCB is needed for a heat sink. The MIC4685 allows for a high degree of safety. It has a Applications wide input voltage range of 4V to 30V (34V transient), Point-of-load power supplies allowing it to be used in applications where input voltage transients may be present. Built-in safety features include Simple high-efciency step-down regulators over-current protection, frequency-foldback short-circuit 5V to 3.3V/2A conversion protection, and thermal shutdown. 12V to 5V/3.3V/2.5V/1.8V 3A conversion The MIC4685 is available in a 7-pin SPAK package with a Dual-output 5V conversion junction temperature range of 40C to +125C. Base stations Data sheets and support documentation can be found on LCD power supplies Micrels web site at www.micrel.com. Battery chargers Typical Application V IN MIC4685 R C BS 8V to 30V 2 1 0.33F/50V IN BS V OUT L1 1.8V/3A 5 6 EN SW R1 39mH C IN 3 3.01k C FB OUT 33F 330F D1 R2 35V GND 6.3V 3A 6.49k 4, Tab 40V 1.8V Output Converter SuperSwitcher is a trademark of Micrel, Inc Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC4685 Ordering Information Part Number Junction Voltage Package Temp. Range Standard RoHS Compliant* MIC4685BR MIC4685WR Adj. 40 to +125C 7-Pin SPAK MIC4685WR EV Adj. Evaluation Board * RoHS compliant with high-melting solder exemption. Pin Configuration 7NC 6SW 5EN 4GND 3FB 2IN 1BS 7-Pin SPAK (R) Pin Description Pin Number Pin Name Pin Function 1 BS Bootstrap Voltage Node (External Component): Connect to external boost capacitor. 2 IN Supply (Input): Unregulated +4V to 30V supply voltage (34V transient) 3 FB Feedback (Input): Outback voltage feedback to regulator. Connect to 1.235V tap of resistive divider. 4, Tab GND Ground 5 EN Enable (Input): Logic high = enable logic low = shutdown 6 SW Switch (Output): Emitter of NPN output switch. Connect to external storage inductor and Schottky diode. 7 NC No Connect. Tie this pin-to-ground. M9999-012610 January 2010 2