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US3018

5 BIT PROGRAMMABLE SYNCHRONOUS BUCK PLUS LDO CONTROLLER AND 200mA LDO ON BOARD

Unisem 

US3018

5 BIT PROGRAMMABLE SYNCHRONOUS BUCK PLUS

FEATURES

LDO CONTROLLER AND 200mA LDO ON BOARD

PRELIMINARY DATASHEET

DESCRIPTION

Provides Single Chip Solution for Vcore, GTL+

& Clock Supply

200 mA On board LDO regulator

Designed to meet the latest Intel specification

for Pentium II™

On board DAC programs the output voltage

from 1.3V to 3.5V

Linear regulator controller on board for 1.5V

GTL+ supply

Loss less Short Circuit Protection with HICCUP

Synchronous operation allows maximum effi-

ciency

Patented architecture allows fixed frequency

operation as well as 100% duty cycle during

dynamic load

Soft Start

High current totem pole driver for direct driv-

ing of the external Power MOSFET

Power Good function Monitors all Outputs

OVP Circuitry Protects the Switcher Output and

generates a Fault signal

Thermal Shutdown

Logic Level Enable Input

APPLICATIONS

The US3018 controller IC is specifically designed to meet

Intel specification for Pentium II™ microprocessor ap-

plications as well as the next generation of P6 family

processors. The US3018 provides a single chip con-

troller IC for the Vcore , LDO controller for GTL+

and an internal 200mA regulator for clock supply

which are required for the Pentium II applications.

These devices feature a patented topology that in com-

bination with a few external components as shown in

the typical application circuit ,will provide in excess of

18A of output current for an on- board DC/DC converter

while automatically providing the right output voltage via

the 5 bit internal DAC. The US3018 also features, loss

less current sensing for both switchers by using the

Rds-on of the high side Power MOSFET as the sens-

ing resistor, internal current limiting for the clock

supply, 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. Other fea-

tures of the device are ; Undervoltage lockout for both

5V and 12V supplies, an external programmable soft

start function , programming the oscillator frequency via

an external resistor, OVP circuitry for both switcher out-

puts and an internal thermal shutdown.

Total Power Soloution for Pentium II processor

application

TYPICAL APPLICATION

5V

3.3V

Vout3

US3018 SWITCHER1

CONTROL

LINEAR

LINEAR

CONTROL REGULATOR

Vout1

3018app3-1.1

Vout2

Notes: Pentium II is trade mark of Intel Corp.

PACKAGE ORDER INFORMATION

Ta (°C)

0 TO 70

Device

US3018CW

Rev. 1.4

12/8/00

Package

24 pin Plastic SOIC WB

4-1

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