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
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 VDDQ 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 VOUT3(1.5V) and
VOUT4(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 RDS(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.
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 VDDQ
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
APPLICATIONS
Total power solution for next generation Intel
processor application
AMD K7 Low Cost Solution
TYPICAL APPLICATION
5V
3.3V
LINEAR
CONTROL
SWITCHER
CONTROL
VOUT1
V
OUT
2
3
IRU3027
LINEAR
CONTROL
LINEAR
CONTROL
VOUT
VOUT4
Figure 1 - Typical application of IRU3027.
PACKAGE ORDER INFORMATION
TA (8C)
DEVICE
PACKAGE
0 To 70
IRU3027CW
28-Pin Plastic SOIC WB
Rev. 1.5
07/17/02
www.irf.com
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