RT8057GQW(2) Richtek

RT8057 2.25MHz 1A Synchronous Step-Down Converter General Description Features zz z zz 2.7V to 5.5V Wide Input Operation Range The RT8057 is a high efficiency Pulse-Width-Modulated zz z zz 2.25MHz Fixed-Frequency PWM Operation (PWM) step-down DC/DC converter, capable of delivering zz z zz Up to 1A Output Current 1A output current over a wide input voltage range from 2.7V zz z zz Up to 90% Efficiency to 5.5V. The RT8057 is ideally suited for portable electronic zz z zz 0.6V Reference Allows Low Output Voltage devices that are powered from 1-cell Li-ion battery or from zz z zz Internal Soft-Start other power sources such as cellular phones, PDAs, hand- zz z zz No Schottky Diode Required held devices, game console and related accessories. zz z zz Internal Compensation to Reduce External The internal synchronous rectifier with low R DS(ON) Components dramatically reduces conduction loss at PWM mode. zz z zz Low Dropout Operation : 100% Duty Cycle No external Schottky diode is required in practical zz z zz RoHS Compliant and Halogen Free applications. The RT8057 enters Low Dropout Mode when normal Pulse -Width Mode cannot provide regulated output Applications voltage by continuously turning on the upper P-MOSFET. z Portable Instruments The RT8057 enters shut-down mode and consumes less z Game Console and Accessories than 1A when the EN pin is pulled low. The switching z Microprocessors and DSP Core Supplies ripple is easily smoothed-out by small package filtering z Cellular Phones elements due to a fixed operating frequency of 2.25MHz. z Wireless and DSL Modems The RT8057 is available in a small WDFN-6SL 2x2 package. z PC Cards Ordering Information Pin Configurations RT8057 (2) (TOP VIEW) Taping Type ( Pin1 at Q2) LX 1 6 GND Package Type NC 2 5 VIN QW : WDFN-6SL 2x2 (W-Type) 3 7 4 FB EN Lead Plating System WDFN-6SL 2x2 G : Green (Halogen Free and Pb Free) Note : Marking Information Richtek products are : J7 : Product Code RoHS compliant and compatible with the current require- W : Date Code J7W ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. DS8057-03 November 2011 www.richtek.com 1 GNDRT8057 Typical Application Circuit L1 RT8057 2.2H 1 V 5 OUT V LX IN VIN 2.3V C IN C OUT 4 C1 R1 EN 4.7F 10F 10pF 680k 3 FB 6, 7 (Exposed Pad) R2 GND 240k Function Pin Description Pin No. Pin Name Pin Function 1 LX Switch Node. Connect to the external inductor. 2 NC No Internal Connection. Connect to GND. 3 FB Feedback Pin. Connect to the external resistor divider. 4 EN Chip Enable (Active High). 5 VIN Power Input. Connect to the input capacitor. 6, Power GND. The Exposed Pad must be soldered to a large PCB and connected GND 7 (Exposed Pad) to GND for maximum power dissipation. Function Block Diagram EN VIN R S1 OSC & Current Shutdown Limit Control Detector Slope Compensation Current Sense Error Control Driver Amplifier LX Logic FB PWM Comparator R C R S2 COMP UVLO & GND Power Good Detector V REF www.richtek.com DS8057-03 November 2011 2