RT7275/76 TM 3A, 18V, 700kHz ACOT Synchronous Step-Down Converter General Description Features zz z zz Fast Transient Response The RT7275/76 are high-performance 700kHz 3A step- zz z zz Steady 700kHz Switching Frequency down regulators with internal power switches and At all Load Currents (RT7275) synchronous rectifiers. They feature quick transient Discontinuous Operating Mode at Light Load response using their Advanced Constant On-Time TM (RT7276) (ACOT ) control architecture that provides stable zz z zz 3A Output Current operation with small ceramic output capacitors and without TM zz z zz Advanced Constant On-Time (ACOT ) Control complicated external compensation, among other benefits. zz z zz Optimized for Ceramic Output Capacitors The input voltage range is from 4.5V to 18V and the output zz z zz 4.5V to 18V Input Voltage Range is adjustable from 0.765V to 8V. zz z zz Internal 90m Switch and 60m Synchronous TM The proprietary ACOT control improves upon other fast- Rectifier response constant on-time architectures, achieving nearly zz z zz 0.765V to 8V Adjustable Output Voltage constant switching frequency over line, load, and output zz z zz Externally-adjustable, Pre-biased Compatible Soft- voltage ranges. Since there is no internal clock, response Start to transients is nearly instantaneous and inductor current zz z zz Cycle-by-Cycle Current Limit can ramp quickly to maintain output regulation without zz z zz Optional Output Discharge Function (PTSSOP-14 large bulk output capacitance. The RT7275/76 are stable Only) with and optimized for ceramic output capacitors. zz z zz Output Over- and Under-voltage Shut-down With internal 90m switches and 60m synchronous rectifiers, the RT7275/76 display excellent efficiency and Applications good behavior across a range of applications, especially z Industrial and Commercial Low Power Systems for low output voltages and low duty cycles. Cycle-by- z Computer Peripherals cycle current limit, input under-voltage lock-out, z LCD Monitors and TVs externally-adjustable soft-start, output under- and over- z Green Electronics/Appliances voltage protection, and thermal shutdown provide safe and z Point of Load Regulation for High-Performance DSPs, smooth operation in all operating conditions. FPGAs, and ASICs The RT7275 and RT7276 are each available in WDFN-10L z Not Recommended for Sink/Source Applications 3x3 and PTSSOP-14 packages, with exposed thermal pads. Fast-Transient Response RT7275 Simplified Application Circuit V OUT (20mV/Div) RT7275/76 V IN VIN SW V OUT VINR BOOT Input Signal FB EN Power Good PGOOD VOUT I PVCC OUT SS (2A/Div) PGND GND VIN = 12V, VOUT = 1.05V, IOUT = 0 to 3A Time (100s/Div) Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS7275/76-00 January 2013 www.richtek.com 1RT7275/76 Ordering Information Pin Configurations RT7275/76 (TOP VIEW) Package Type VOUT 14 VINR CP : TSSOP-14 (Exposed Pad) 2 13 FB VIN QW : WDFN-10L 3x3 (W-Type) 3 12 PVCC BOOT 4 11 PGND SW SS Lead Plating System 5 10 GND SW G : Green (Halogen Free and Pb Free) 6 9 PGND PGOOD 15 7 8 EN PGND Operating Mode 75 : Continuous Switching Mode TSSOP-14 (Exposed Pad) 76 : Discontinuous Operating Mode at Light Load EN 1 10 VIN Note : 9 2 VIN FB 8 PVCC 3 BOOT Richtek products are : 4 7 SS SW 11 5 PGOOD SW RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. WDFN-10L 3x3 Suitable for use in SnPb or Pb-free soldering processes. Marking Information RT7276GCP RT7275GCP RT7276GCP : Product Number RT7275GCP : Product Number RT7276 YMDNN : Date Code RT7275 YMDNN : Date Code GCPYMDNN GCPYMDNN RT7276GQW RT7275GQW 2C= : Product Code 4C= : Product Code YMDNN : Date Code YMDNN : Date Code 2C=YM 4C=YM DNN DNN Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS7275/76-00 January 2013 2 PGND 9