General Description
The RT8237E 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 RT8237E 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 pre-set frequency selections
minimize design effort required for new designs. The
RT8237E is intended for CPU core, chipset, DRAM, or
other low voltage supplies as low as 0.7V. The RT8237E
is available in the WDFN-10L 3x3 package.

Features
 Wide Input Voltage Range : 2.7V 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 Setting
 Soft-Start Control
 Drives Large Synchronous-Rectifier FETs
 Integrated Boot Switch
 Built-In OVP/OCP/UVP
 Thermal Shutdown
 Power Good Indicator
 RoHS Compliant and Halogen Free

Applications
 Notebook Computers
 CPU Core Supply
 Chipset/RAM Supply as Low as 0.7V
 Generic DC-DC Power Regulator