1

TM

File Number 9041

ISL6440A

Advanced PWM and Triple Linear Power

Controller for Gateway Applications

The ISL6440A provides the power control and protection for

four output voltages required by microprocessors used in

high-performance, graphics-intensive gateway applications.

The IC integrates a voltage-mode PWM controller and three

linear controllers, as well as the monitoring and protection

functions into a 28 lead SOIC package.

The synchronous rectified buck converter includes an Intel®-

compatible, TTL five-input, digital-to-analog converter (DAC)

increments. The precision reference and voltage-mode

control provide

±1% static regulation. A TTL-compatible

signal applied to the SELECT pin dictates which method of

control is used for the AGP bus power. A low state results in

linear control of the AGP bus to 1.5V, while a high state

transitions the output through a linearly controlled soft-start

to 3.3V, followed by full enhancement of the external

MOSFET to pass the input voltage. The other two linear

regulators provide fixed output voltages of 1.5V GTL bus

power and 1.8V power for the north/south bridge core and/or

cache memory. These levels are user-adjustable by means

of an external resistor divider and pulling the FIX pin low. All

linear controllers can employ either N-Channel MOSFETs or

bipolar NPNs for the pass transistor.

The ISL6440A monitors all the output voltages. A single

power good signal is issued when the core is within

±10% of

the DAC setting and all other outputs are above their under-

voltage levels. Additional built-in overvoltage protection for

the core output uses the lower MOSFET to prevent output

voltages above 115% of the DAC setting. The PWM

controller’s overcurrent function monitors the output current

by using the voltage drop across the upper MOSFET’s

Features

• Provides four regulated voltages

- Microprocessor core, AGP bus, memory, and GTL bus

power

• Drives N-Channel MOSFETs

• Linear regulator drives compatible with both MOSFET and

bipolar series pass transistors

• Fixed or externally resistor-adjustable linear outputs

• Simple single-loop control design

- Voltage-mode PWM control

• Fast PWM converter transient response

- High-bandwidth error amplifier

- Full 0–100% duty ratio

• Excellent output voltage regulation

- Core PWM output:

±1% over temperature

- Other outputs:

±3% over temperature

• TTL-compatible 5-bit DAC core output voltage selection

- Shutdown feature removed when all inputs high

• Power-good output voltage monitor

• Overvoltage and overcurrent fault monitors

- Switching regulator does not require extra current

• Small converter size

- Constant frequency operation

- 200kHz free-running oscillator; programmable from

50kHz to over 1MHz

- Small external component count

Applications

• Power regulation for gateway processors

Pinout

ISL6440A (SOIC)

TOP VIEW

Ordering Information

PART NUMBER

TEMP.

PACKAGE

PKG.

NO.

ISL6440ACB

0 to 70

28 Ld SOIC

M28.3

DRIVE2

FIX

VID4

VID3

VSEN2

SELECT

SS

FAULT/RT

VSEN4

VCC

PGND

LGATE

PHASE

DRIVE3

COMP

GND

VAUX

DRIVE4

UGATE

PGOOD

VID2

SD

VSEN1

VSEN3

VID1

VID0

OCSET

FB

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

Data Sheet

October 2001

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 321-724-7143

Copyright © Intersil Americas Inc. 2001. All Rights Reserved

Intel® is a registered trademark of Intel Corporation.