General Description

The RT6543A/B PWM controller provides high efficiency,

excellent transient response, and high DC output accuracy

for stepping down high voltage batteries to generate low

voltage CPU core, I/O, and chipset RAM.

The RT6543A/B supports on chip voltage programming

function between 0V and 1.8V by controlling VID1/VID0

inputs.

Compared with conventional current-mode PWMs, the

RT6543A/B achieves high efficiency without any current

sensing resistors. Furthermore, the RT6543A/B has ability

to drive synchronous rectifier MOSFETs and enters diode

emulation mode at light load condition that also save lots

of power consumption. Besides, the RT6543A/B equips

with UVLO, OVP, UVP, OTP and current limit protection.

All above functions are integrated in a WQFN-20L-3x3

package.

Features

A High Efficiency Step-Down DC-DC Controller

Built-in 1% Reference Voltage

2-Bit Programmable Output Voltage with Integrated

Adjustable Switching Frequency

Input Voltage Range : 3V to 24V

Internal Soft-Start to Reduce Inrush Current

Capability of Driving Large Synchronous Rectifier

MOSFETs

Power Good Indicator

Cycle-by-Cycle Current Limit

Over-/Under-Voltage Protection

Thermal Shutdown

RT6543A : Slew Down Mode as VID Change

RT6543B : Decay Down Mode as VID Change