RT8075 Dual 1A, 1.25MHz Synchronous Step-Down Converter General Description Features z z z z z 2.5V to 5.5V Input Range The RT8075 is a high efficiency Pulse-Width-Modulated z z z z z 1A 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 1A output current over a wide input voltage z z z z z 95% Efficiency range from 2.5V to 5.5V, the RT8075 is ideally suited for z z z z z No Schottky Diode Required portable electronic devices that are powered from 1-cell z z z z z 0.6V Reference Allows Low Output Voltage Li-ion battery or from other power sources such as cellular z z z z z Low Dropout Operation : 100% Duty Cycle phones, PDAs, PC WLAN card and hand-held devices. z z z z z Small 10-Lead WDFN Package Three operating modes are available including : PWM z z z z z RoHS Compliant and Halogen Free mode, Low Dropout Mode and shut-down mode. The Internal synchronous rectifier with low R dramatically DS(ON) Applications reduces conduction loss at PWM mode. No external z Portable Instruments Schottky diode is required in practical application. The z Microprocessors and DSP Core Supplies RT8075 enters Low Dropout mode when normal PWM z Cellular Phones cannot provide regulated output voltage by continuously z Wireless and DSL Modems turning on the upper P-MOSFET. The RT8075 enters shut- z PC Cards down mode and consumes less than 0.1A when the EN pin is pulled low. Ordering Information The switching ripple is easily smoothed-out by small RT8075 package filtering elements due to the fixed operating Package Type frequency of 1.25MHz. The RT8075 is available in the QW : WDFN-10L 3x3 (W-Type) WDFN-10L 3x3 package. Lead Plating System G : Green (Halogen Free and Pb Free) Pin Configurations Z : ECO (Ecological Element with Halogen Free and Pb free) (TOP VIEW) Note : 1 10 LX1 EN1 2 9 FB1 GND Richtek products are : 3 8 VIN2 VIN1 4 7 GND FB2 RoHS compliant and compatible with the current require- 11 5 LX2 EN2 ments of IPC/JEDEC J-STD-020. WDFN-10L 3x3 Suitable for use in SnPb or Pb-free soldering processes. Marking Information RT8075GQW RT8075ZQW 38= : Product Code 38 : Product Code YMDNN : Date Code YMDNN : Date Code 38=YM 38 YM DNN DNN DS8075-04 April 2011 www.richtek.com 1 GND 9RT8075 Typical Application Circuit L1 2.2H RT8075 10 LX1 V OUT1 8 V IN1 VIN1 R1 C IN1 C FF1 110k 4.7F 2 C OUT1 FB1 3 10F V IN2 VIN2 R2 C 110k IN2 L2 4.7F 2.2H 5 Chip Enable 1 LX2 V OUT2 EN1 6 R3 EN2 C FF2 110k 4, 9, 7 C OUT2 GND FB2 11 (Exposed Pad) 10F 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. Ground. The exposed pad must be soldered to a large PCB and 4, 9, 11 (Exposed Pad) GND connected to GND for maximum power dissipation. www.richtek.com DS8075-04 April 2011 2