RT9238 Datasheet, PDF (1/24 Pages) List of Unclassifed Manufacturers – VRM 8.5 PWM AND TRIPLE LINEAR POWER SYSTEM CONTROLLER

Preliminary
RT9238
VRM8.5 PWM and Triple Linear Power System Controller
General Description
The RT9238 is a 4-in-one power controller optimized
for high-performance microprocessor and computer
applications. The IC integrates a PWM controller,
triple linear controller as well as monitoring and
protection functions into a 28-pin SOP package. The
PWM controller regulates the microprocessor core
voltage with a synchronous buck converter. The first
linear controller supplies the computer system’s
AGTL+ 1.2V bus power. The second linear controller
provides power for the 1.5V AGP bus and the 3rd
linear controller provides 1.8V power for the chipset
core voltage and/or cache memory circuits.
The RT9238 features an Intel VRM8.5 compatible,
TTL 5-bit programmable DAC that adjusts the core
voltage from 1.090V to 1.865V in 25mV steps. The 5-
bit DAC has a typical ±1% tolerance. The linear
regulators provide fixed output voltages of 1.2V
(V_OUT2), 1.5V (V_OUT3) and 1.8V (V_OUT4) or user-
adjustable with an internal 1.265V reference. All the
three linear regulators drive external N-MOSFET or
NPNs bipolar for the pass transistor.
The RT9238 monitors all the output voltages. A
power-good signal is issued when the core voltage is
within ±10% of the DAC setting and the other levels
are above their under-voltage levels. Additional build-
in over-voltage protection for the core output uses the
lower MOSFET to prevent output voltage above
115% of the DAC setting. The PWM over-current
function monitors the output current using the voltage
drop across the MOSFET’s R_DS(ON), which
eliminates the need for a current sensing resistor.
Applications
z Motherboard Power Regulation for Computers
Features
z 4-in-one Regulated Voltages for Microprocessor
Core, AGTL+ Bus, AGP Bus Power, and
North/South Bridge Core
z Compatible with ISL6524
z Power-good Output Voltage Monitor
Switching section
z VRM8.5 TTL-Compatible 5-bit DAC
Programmable from 1.090V to 1.865V
z ±1% DAC Accuracy
z Fast Transient Response
z VRM 8.5 Voltage Droop Tuning Uses MOSFET
R _DS(ON)
z Fixed 200KHz Switching Frequency
z Adaptive Non-overlapping Gate Driver
z Over-current Monitor Uses MOSFET R_DS(ON)
z Over-voltage Protection Uses Lower MOSFET
Linear Section
z Fixed or User-adjustable Linear Regulator
Output Voltage
z MOSFET and NPN Driving Capability
z Ultra Fast Response Speed
z Under-voltage Protection
z Internal Thermal Shutdown
Pin Configurations
Part Number
Pin Configurations
RT9238CS
(Plastic SOP-28)
DRIVE2 ¹
FIX 2
VID3 ³
VID2 4
VID1 5
VID0 6
VID25 7
PGOOD 8
VTTPG 9
FAULT/VID4 ¹⁰
VSEN2 ¹¹
SS24 ¹²
SS13 13
VSEN4 14
28 VCC
27 UGATE1
26 PHASE1
25 LGATE1
24 PGND
23 OCSET1
22 FB1
21 _VDAC
20 ICOMP
19 _VSEN3
18 DRIVE3
17 _GND
16 VAUX
15 _DRIVE4
DS9238-01 July 2001
www.richtek-ic.com.tw
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