Preliminary
RT9224E
VRM 8.5 Synchronous PWM Buck Converter
Controller and Output Voltage Monitor
General Description
The RT9224E is a high speed switching controller designed
for use in Synchronous DC/DC buck converter for modern
CPUs. The regulated output voltage is digitally
programmable from 1.05V to 1.825V by a 5-bit DAC which
provides initial accuracy of ±1%. The RT9224E drives two
external N-Channel MOSFETs, providing high efficiency
and eliminating the need for high cost P-Channel devices.
It senses the output current across the on-resistance of
the N-channel MOSFET and provides an adjustable current
limit without external sense resistor.
RT9224E monitors the output voltage and provides the
output signal for power-good and over-voltage protections.
The switching frequency is 200kHz. The high switching
frequency cooperating with a high speed error amplifier
maintains a fast response to the dynamic load of modern
CPUs.
Ordering Information
RT9224E
Package Type
S : SOP-20
Operating Temperature Range
C : Commercial Standard
P : Pb Free with Commercial Standard
Features
Simple Voltage-Mode PWM Control with Buck
Rectification
±1% DAC Output Voltage Accuracy
5-Bit Digital-to-Analog Output Voltage Range from
1.05V to 1.825V
Fast Transient Response and Excellent Output
Voltage Regulation
Fault Protection for Over-Voltage and Over-Current
Power-Good Output Voltage Monitor
Applications
Power Supply for VRM 8.5 Microprocessors
Low-voltage Distributed Power Supplies
High Power 5V to 1.05V to 1.85V Switching Regulator
Pin Configurations
(TOP VIEW)
VSEN
OCSET
SS
VID25
VID0
VID1
VID2
VID3
NC
FB
2
3
4
5
6
7
8
9
10
20 NC
19 OVP
18 VCC
17 LGATE
16 PGND
15 BOOT
14 UGATE
13 PHASE
12 PGOOD
11 GND
SOP-20
DS9224E-02 March 2004
www.richtek.com
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