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