General Description

The RT8237L 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 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 RT8237L 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 to 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 pre-set frequency

selections minimize the effort required for new designs.

The RT8237L is intended for CPU core, chipset, DRAM,

or other low voltage supplies down to 0.7V. The

RT8237L is available in the VQFN-16L 3x3 package.

Features

⚫ Wide Input Voltage Range: 4.5V to 26V

⚫ Output Voltage Range: 0.7V to 3.3V

⚫ Built-in 0.5% 0.7V Reference Voltage

⚫ Quick Load-Step Response within 100ns

⚫ 4700ppm/C Current Source for Current Limit

RDS(ON)

⚫ Adjustable Current Limit with Low-side MOSFET

⚫ 4 Selectable Frequency Settings

⚫ Soft-Start Control

⚫ Drives Large Synchronous-Rectifier FETs

⚫ Integrated Boot Switch

⚫ Built-in OCP/UVP

⚫ Thermal Shutdown

⚫ Power Good Indicator

Applications

⚫ Notebook Computers

⚫ CPU Core Supply

⚫ Chipset/RAM Supply Down to 0.7V

⚫ Generic DC-DC Power Regulator

The recommended junction temperature range is −40C

to 125C and ambient temperature range is −40C to

85C.