General Description
The RT6542A PWM controller provides high efficiency,
excellent transient response, and high DC output accuracy
needed for stepping down high voltage batteries to
generate low voltage CPU core, I/O, and chipset RAM
supplies in notebook computers.
The RT6542A supports on chip voltage programming
function between 0.85V and 1.05V by controlling GX digital
inputs.
The constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
“instant-on” response to load transients while maintaining
a relatively constant switching frequency.
The RT6542A achieves high efficiency at a reduced cost
by eliminating the current-sense resistor found in
traditional current-mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs and enter diode emulation mode at
light load condition. The buck conversion allows this device
to directly step down high voltage batteries at the highest
possible efficiency. The RT6542A is intended for CPU core,
chipset, DRAM, or other low voltage supplies as low as
0.7V.
The RT6542A is available in a WDFN-14L 3x2 package.

Features
 Intel Cannon VR Support
 Built-in 1% Reference Voltage
 2-Bit Programmable Output Voltage with Integrated
Transition Support
 Support Intel LPM (Low-Power Mode) Feature
 4700ppm/°C Programmable Current Limit by Low-
Side RDS(ON) Sensing
 3V to 26V Battery Input Range
 Internal Voltage Ramp Soft-Start Control
 Drives Large Synchronous Rectifier FETs
 Integrated Boost Switch
 Over/Under-Voltage Protection
 Thermal Shutdown
 Power Good Indicator
 RoHS Compliant and Halogen Free
 Tiny 14-Lead WDFN Package

Applications
 Notebook Computers
 CPU/GPU Core Supply
 Chipset/RAM Supply
 Generic DC-DC Power Regulator