REJ03D0790-0300 Rev.3.00 May 14, 2008

Page 1 of 9

R2A20101BM/NP

Monolithic Synchronous Step-Down DC/DC Converter

REJ03D0790-0300

Rev.3.00

May 14, 2008

Features

• Built-in low Ron power MOS FETs

Pch Ron = 0.30

Ω (Typ), Nch Ron = 0.14 Ω (Typ)

• High switching frequency: 2 MHz (Max)

• Output current: 650 mA (Max)

• Output ON/OFF control

• Vout control

• Power good monitor

• Current share for redundant power supply operation

• Vout = 0.5 V to (VIN – 0.5) V

Application

• POL (Point of Load) power supplies

• Power supply for microcomputer systems

MCU-Core, I/O, Memory (DDR, SRAM, FLASH, HDD, etc.), FPGA, DSP, Graphic Processor

• Battery powered equipment systems

Cellular phone (CDMA power amplifier, MCU, DSP, ASIC), PDA, Digital camera, Portable game, Handy terminal

Operating Circuit Example

R2A20101

VIN

Vout

1.8V

Iout: Up to 650mA

Vin

2.5V to 5.5V

Cin

4.7

µF

Cout

4.7

µF

L1

2.2

µH

Ccf1

47pF

VREF

(Internal Vref = 0.5V)

EAO

PWGD

Power Good

Signal Output

ON/

OFF

LX

AGND

VFB

CRFB

PGND

Error Amp. Output

(for Current Share)

Vref Input

(for Vout Control)

Rcf2

68k

Ω

Notes: 1. All ceramic capacitor

2. Rcf1 : Rcf2(recommend) = 3 : 2

3. fsw is adjustable by Ccf1, Rcf1, and Rcf2.

Rcf1

100k

Ω

Rvf1

150k

Ω

Rvf2

390k

Ω