RT8035A Dual 800mA, 1.25MHz Synchronous Step-Down Converter General Description Features z z z z z 2.5V to 6V Input Range The RT8035A is a high-efficiency Pulse-Width-Modulated z z z z z 800mA Output Current (PWM) dual step-down DC/DC converter. Capable of z z z z z 1.25MHz Fixed Frequency PWM Operation delivering up to 800mA output current over a wide input z z z z z 95% Efficiency voltage range from 2.5V to 6V, the RT8035A is ideally z z z z z No Schottky Diode Required suited for portable electronic devices that are powered z z z z z 0.6V Reference Allows Low Output Voltage from 1-cell Li-ion battery or from other power sources such z z z z z Low Dropout Operation : 100% Duty Cycle as cellular phones, PDAs, PC WLAN card and hand-held z z z z z Small 10-Lead WDFN Package devices. z z z z z RoHS Compliant and Halogen Free Three operating modes are available including : PWM mode, Low-Dropout Mode and shut-down mode. The Applications Internal synchronous rectifier with low R dramatically DS(ON) z Portable Instruments reduces conduction loss at PWM mode. No external z Microprocessors and DSP Core Supplies Schottky diode is required in practical application. The z Cellular Phones RT8035A enters Low-Dropout mode when normal PWM z Wireless and DSL Modems cannot provide regulated output voltage by continuously z PC Cards turning on the upper P-MOSFET. The RT8035A enters shut-down mode and consumes less than 0.1A when Pin Configurations the EN pin is pulled low. (TOP VIEW) The switching ripple is easily smoothed-out by small package filtering elements due to the fixed operating 1 10 EN1 LX1 2 9 FB1 GND frequency of 1.25MHz. The RT8035A is available in the 3 8 VIN2 VIN1 4 7 GND FB2 11 WDFN-10L 3x3 package. 5 LX2 EN2 WDFN-10L 3x3 Ordering Information RT8035A Marking Information Package Type 2A= : Product Code QW : WDFN-10L 3x3 (W-Type) YMDNN : Date Code Lead Plating System 2A=YM G : Green (Halogen Free and Pb Free) DNN Note : Richtek products are : RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8035A-02 November 2013 www.richtek.com 1 GND 9RT8035A Typical Application Circuit L1 2.2H RT8035A 10 8 LX1 V OUT1 V IN1 VIN1 C R1 IN1 C FF1 4.7F 110k 2 C OUT1 FB1 3 10F V IN2 VIN2 R2 C 110k IN2 4.7F L2 2.2H 5 Chip Enable 1 V LX2 EN1 OUT2 6 R3 EN2 C FF2 110k 7 C OUT2 4, 9 FB2 GND 10F 11 (Exposed Pad) R4 110k Function Block Diagram EN1/EN2 VIN1/VIN2 RS1 OSC & Current Shutdown Limit Control Detector Slope Compensation Current Sense Control Driver LX1/LX2 Error Logic Amplifier PWM FB1/FB2 Comparator RC UVLO & RS2 COMP Power Good Detector GND V REF Functional Pin Description Pin No. Pin Name Pin Function 1 EN1 Chip Enable of Channel 1 (Active High). 2 FB1 Feedback Input of Channel 1. 3 VIN2 Power Supply Input of Channel 2. 5 LX2 Switching Node of Channel 2. 6 EN2 Chip Enable of Channel 2 (Active High). 7 FB2 Feedback Input of Channel 2. 8 VIN1 Power Supply Input of Channel 1. 10 LX1 Switching Node of Channel 1. GND Ground. The exposed pad must be soldered to a large PCB and connected to 4, 9, 11 (Exposed Pad) GND for maximum power dissipation. Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS8035A-02 November 2013 2