RT7263B 3A, 21V 500kHz Synchronous Step-Down Converter General Description Features zz z zz Wide Input Range : 4.5V to 21V The RT7263B is a synchronous step-down regulator with zz z zz Adjustable Output from 0.603V to 15V an internal power MOSFET. It achieves 3A of continuous zz z zz 3A Output Current output current over a wide input supply range with excellent zz z zz 120m/40m Internal Power MOSFET Switch load and line regulation. Current mode operation provides zz z zz Internal Compensation Minimizes External Parts fast transient response and eases loop stabilization. zz z zz 500kHz Fixed Switching Frequency Fault condition protection includes cycle-by-cycle current zz z zz Synchronized External Clock from 300kHz to 2MHz limiting and thermal shutdown. An adjustable soft-start zz z zz Adjustable Soft-Start reduces the stress on the input source at startup. zz z zz Cycle-by-Cycle Over Current Limit The RT7263B requires a minimal number of readily zz z zz Thermal Shutdown Protection available external components, providing a compact zz z zz Small 14-Lead WDFN Package solution. zz z zz RoHS Compliant and Halogen Free Ordering Information Applications RT7263B z Distributive Power Systems Package Type z Battery Charger QW : WDFN-14L 4x3 (W-Type) z DSL Modems Lead Plating System z Pre-Regulator for Linear Regulators Z : ECO (Ecological Element with Halogen Free and Pb free) Marking Information Note : 10 : Product Code Richtek products are : YMDNN : Date Code 10 YM RoHS compliant and compatible with the current require- DNN ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit V VIN BOOT IN C BOOT RT7263B C IN L VCC SW V OUT C C R1 R T FB C OUT SYNC SYNC C SS R2 EN SS ON/OFF AGND GND Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS7263B-01 September 2012 www.richtek.com 1RT7263B Pin Configurations (TOP VIEW) VIN 1 14 AGND 2 13 SW GND SW 3 12 GND 4 11 SW VCC GND 5 10 SS SW 69 BOOT EN 15 SYNC78 FB WDFN-14L 4x3 Function Pin Description Pin No. Pin Name Pin Function Power Input. VIN supplies the power to the IC, as well as the step-down 1 VIN converter switches. Drive VIN with a 4.5V to 21V power source. Bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC. Switch Node. SW is the switching node that supplies power to the output. 2, 3, 4, 5 SW Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BOOT to power the high side switch. Bootstrap for High Side Gate Driver. Connect a 100nF or greater capacitor from 6 BOOT SW to BOOT to power the high side switch driver. External Frequency Synchronization Input. Connect an external clock on this pin 7 SYNC changes the switching frequency. Feedback Input. FB senses the output voltage via an external resistive voltage 8 FB divider. The feedback reference voltage is 0.603V typically. Enable Control Input. Floating this pin or connecting this pin to logic high will 9 EN enable the device and connecting this pin to GND will disable the device. Soft-Start Control Input. Connect a capacitor from SS to GND to set the soft-start 10 SS period. Bias Supply. Decouple with 0.1F to 0.22F capacitor between this pin and 11 VCC GND. 12, 13, Ground. The exposed pad must be soldered to a large PCB and connected to GND 15 (Exposed Pad) GND for maximum power dissipation. 14 AGND Analog Ground. Connect this pin to the system ground in PCB layout. Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS7263B-01 September 2012 2