RT9231A
Advanced PWM and Triple Linear Power Controller
General Description
The RT9231A 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鈥檚
AGP 1.5V or 3.3V bus power. The second linear
controller provides power for the 1.5V GTL bus and
the 3rd linear controller provides 1.8V power for the
North/South Bridge core voltage and/or cache
memory circuits.
The RT9231A features an Intel-compatible, TTL 5-bit
programmable DAC that adjusts the core voltage
from 2.1V to 3.5V in 0.1V increments and from 1.3V
to 2.05V in 0.05V steps. The 5-bit DAC has a typical
鹵1%
tolerance. The first linear controller is user-
selectable for output level of 1.5V and 3.3V with
鹵2.5%
accuracy. The other two linear controllers
provide fixed output voltages of 1.5V
鹵3%
and 1.8V
鹵3%.
All the three linear controllers drive external N-
MOSFET or NPNs bipolar for the pass transistor.
The RT9231A monitors all the output voltages. A
power-good signal is issued when the core voltage is
within
鹵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鈥檚 R
DS(ON)
,
which
eliminates the need for a current sensing resistor.
Features
4-in-one Regulated Voltages for Microprocessor
Core, AGP Bus, North/South Bridge and/or
Cache Memory, GTL Bus Power
Compatible with HIP6021A
Power-good Output Voltage Monitor
Switching section
5-bit DAC Programmable from 1.3V to 3.5V
鹵1%
DAC Accuracy
Fast Transient Response
Full 0% to 100% Duty Cycle Driver
Fixed 200kHz Switching Frequency
Adaptive Non-overlapping Gate Driver
Over-current Monitor Uses MOSFET R
DS(ON)
Over-voltage Protection Uses Lower MOSFET
Linear Section
Fixed or User-adjustable Linear Regulator
Output Voltage
MOSFET and NPN Driving Capability
Ultra Fast Response Speed
Under-voltage Protection
Internal Thermal Shutdown
Pin Configurations
Part Number
RT9231ACS
(Plastic SOP-28)
DRIVE2
FIX
VID4
VID3
VID2
VID1
VID0
PGOOD
SD
VSEN2
SELECT
SS
FAULT
VSEN4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Pin Configurations
TOP VIEW
VCC
27
UGATE1
26
PHASE1
28
25
24
23
22
21
20
19
18
LGATE1
PGND
OCSET1
VSEN1
FB1
NC
Applications
Full Motherboard Power Regulation for Computer
Low-voltage Distributed Power Supplies
VSEN3
DRIVE3
17
GND
16
VAUX
15
DRIVE4
DS9231A-02 July 2001
www.richtek.com
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