MIC2177 2.5A Synchronous Buck Regulator General Description Features The Micrel MIC2177 is a 200kHz synchronous buck (step- 4.5V to 16.5V input voltage range down) switching regulator designed for high-efficiency, Dual-mode operation for high efficiency (up to 96%) battery-powered applications. PWM mode for > 200mA load current The MIC2177 operates from a 4.5V to 16.5V input and Skip mode for < 200mA load current features internal power MOSFETs that can supply up to 2.5A 100m internal power MOSFETs at 12V input output current. It can operate with a maximum duty cycle of 200kHz preset switching frequency 100% for use in low-dropout conditions. It also features a Low quiescent current shutdown mode that reduces quiescent current to less than 1.0mA in PWM mode 5A. 500A in skip mode The MIC2177 achieves high efficiency over a wide output < 5A in shutdown mode current range by switching between PWM and skip mode. Operating mode is automatically selected according to output 100% duty cycle for low dropout operation conditions. Switching frequency is preset to 200kHz and can Current-mode control be synchronized to an external clock signal of up to 300kHz. Simplified loop compensation The MIC2177 uses current-mode control with internal current Superior line regulation sensing. Current-mode control provides superior line Current limit regulation and makes the regulator control loop easy to Thermal shutdown compensate. The output is protected with pulse-by-pulse Undervoltage lockout current limiting and thermal shutdown. Undervoltage lockout turns the output off when the input voltage is less than 4.5V. The MIC2177 is packaged in a 20-pin wide power SO Applications package with an operating temperature range of 40C to High-efficiency, battery-powered supplies +85C. Buck (step-down) dc-to-dc converters See the MIC2178 for externally selected PWM or skip-mode Cellular telephones operation. Laptop computers Data sheets and support documentation can be found on Hand-held instruments Micrels web site at: www.micrel.com. Battery Charger Typical Application V IN 5V Output 5.4V to 18V Efficiency 100 C1 22F U1 1,2,9 35V 95 VIN 10 ENABLE OUT 20 L1, 50H EN 90 V =6V 3,8 V OUT IN SHUTDOWN SW 18 MIC 5V/1A SYNC D1 2177-5.0 47 C2 MBRS130L 85 PGND 11 100F AUTO 12 10V FB 80 COMP SGND BIAS 2.2 13 1417 19 nF R1 75 SKIP 10k C3 R1 PWM C C 0.01F 10k 70 6.8nF 10 100 1000 2500 OUTPUT CURRENT (mA) Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC2177 Ordering Information Output Switching Part Number Temperature Range Package Lead Finish Voltage Frequency MIC2177-3.3BWM 3.3V 200kHz 40C to +85C 20-Pin Wide SOIC Standard MIC2177-5.0BWM 5.0V 200kHz 40C to +85C 20-Pin Wide SOIC Standard MIC2177BWM Adj. 200kHz 40C to +85C 20-Pin Wide SOIC Standard MIC2177-3.3YWM 3.3V 200kHz 40C to +85C 20-Pin Wide SOIC Pb-Free Pin Configuration VIN 1 20 EN VIN 2 19 BIAS SW 3 18 SYNC PGND 4 17 SGND PGND 5 16 SGND PGND 6 15 SGND PGND 7 14 SGND SW 8 13 COMP VIN 9 12 FB AUTO OUT 10 11 20-Pin Wide SOIC (WM) M9999-042108 April 2008 2