General Description

The RT8249A/B/C is a dual-channel step-down, controller

generating supply voltages for battery-powered systems.

It includes two Pulse-Width Modulation (PWM) controllers

adjustable from 2V to 5.5V, and two fixed 5V/3.3V linear

regulators. Each linear regulator provides up to 100mA

output current and 3.3V linear regulator provides 1

accuracy under 35mA. The RT8249A/B has an oscillator

output to driver the external charge pump application. The

RT8249C provides a mode selection pin, SKIPSEL, to

select Diode-Emulation Mode (DEM) or Audio Skipping

Mode (ASM). Other features include on-board power-up

sequencing, a power-good output, internal soft-start, and

soft-discharge output that prevents negative voltage during

shutdown.

A constant current ripple PWM control scheme operates

without sense resistors and provides 100ns response to

load transient. For maximizing power efficiency, the

RT8249A/B/C automatically switches to the diodeemulation

mode in light load applications. The RT8249A/

B/C is available in the WQFN-20L 3x3 package.

特性 Features

? Support Connected Standby Mode for Ultrabook

? CCRCOT Control with 100ns Load Step Response

? PWM Maximum Duty Ratio > 98

? 5V to 25V Input Voltage Range

? 2V to 5.5V Output Voltage Range

? 5V/3.3V LDOs with 100mA Output Current

? 1 Accuracy on 3.3V LDO Output

? Oscillator Driving Output for Charge Pump

Application

? Internal Frequency Setting

? RT8249A/B : 400kHz/475kHz (CH1/CH2)

? RT8249C : 500kHz/600kHz (CH1/CH2)

? Internal Soft-Start and Soft-Discharge

? 4700ppm/°C RDS(ON) Current Sensing

? Independent Switcher Enable Control

? Built in OVP/UVP/OCP/OTP

? Non-latch UVLO

? Power Good Indicator

? 20-Lead WQFN Package

? RoHS Compliant and Halogen Free