Data Sheet No. PD94146
IRU3027
5-BIT PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER IC
WITH TRIPLE LDO CONTROLLER
FEATURES
DESCRIPTION
Designed to meet VRM 9.0 specification for next
generation microprocessors
On-Board 5-Bit DAC programs the output voltage
from 1.075V to 1.850V in 25mV steps
Linear Regulator Controller On-Board for 1.8V
Provides single chip solution for Vcore, GTL+,
AGP bus, and 1.8V
Automatic Voltage Selection for AGP Slot V
DDQ
Supply
Linear Regulator Controller On-Board for 1.5V
GTL+ Supply
Loss-less Short Circuit Protection for all Outputs
Synchronous operation allows maximum effi-
ciency
Patented architecture allows fixed frequency
operation as well as 100% duty cycle during
dynamic load
Minimum Part Count
Soft-Start
High current totem pole driver for direct driving of
the external power MOSFET
Power Good function monitors all outputs
Over-Voltage Protection Circuitry protects the
switcher output and generates a fault output
The IRU3027 controller IC is specifically designed to meet
VRM 9.0 specification for next generation microproces-
sor applications requiring multiple on-board regulators.
The IRU3027 provides a single chip controller IC for the
Vcore, three LDO controllers, one with an automatic se-
lect pin that connects to the Type Detect pin of the AGP
slot for the AGP V
DDQ
supply, one for GTL+ and the other
for the 1.8V chip set regulator as required for the next
generation PC applications. The IRU3027 is designed to
use either bipolar transistors for V
OUT
3(1.5V) and
V
OUT
4(1.8V). No external resistor divider is necessary
for any of the regulators. The switching regulator fea-
tures a patented topology that in combination with a few
external components as shown in the typical applica-
tion circuit, will provide well in excess of 20A of output
current for an on-board DC-DC converter while automati-
cally providing the right output voltage via the 5-bit inter-
nal DAC. The IRU3027 also features loss-less current
sensing for both switchers by using the R
DS(ON)
of the
high side power MOSFET as the sensing resistor, an
output under-voltage shutdown that detects short circuit
condition for the linear outputs and latches the system
off, and a Power Good window comparator that switches
its open collector output low when any one of the out-
puts is outside of a pre-programmed window.
APPLICATIONS
Total power solution for next generation Intel
processor application
AMD K7 Low Cost Solution
TYPICAL APPLICATION
5V
3.3V
LINEAR
CONTROL
SWITCHER
CONTROL
V
OUT
1
V
OUT
2
IRU3027
LINEAR
CONTROL
V
OUT
3
LINEAR
CONTROL
V
OUT
4
Figure 1 - Typical application of IRU3027.
PACKAGE ORDER INFORMATION
T
A
(8C)
0 To 70
Rev. 1.5
07/17/02
DEVICE
IRU3027CW
www.irf.com
PACKAGE
28-Pin Plastic SOIC WB
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