US3033

4-1

Rev. 1.5

1/14/99

PWM SWITCHER & LINEAR

CONTROLLER IC

TYPICAL APPLICATION

TYPICAL APPLICATION

Typical application of US3033 in a flexible mother board designed for Intel P55

™,P54™

AMD K5,K6

™ as well as Cyrix M1™ and M2™ applications.

TA (°C)

8 PIN PLASTIC

SOIC (S)

0 TO 70

US3033CS

Notes: P54C,P55C,Pentium II are trade marks of Intel Corp. K5 & K6 are trade marks of AMD corp. Cyrix 6X86L,M1,M2 are trade marks

of Cyrix Corp. Power PC is trade mark of IBM Corp.

DESCRIPTION

DESCRIPTION

The US3033 IC combines a switching controller and

a linear regulator controller all in a compact 8 pin

surface mount package, providing a total solution for

dual supply processor applications such as an Intel

P55C

™, AMD K6™, as well as Cyrix 6X86L™ and

the M2

™processors. Typically in these applications a

dual supply regulator converts 5V to 3.3V for I/O supply

and a jumper programmable supply of 1.25V to 3.5V for

CORE supply .The linear regulator controller portion in

the US3033 is a programmable controller allowing flex-

ibility for the I/O regulator and has a minimum of 50mA

drive current capability designed to provide ample cur-

rent for an external pass transistor. The IC uses an inter-

nal regulator generated from the 12V supply to power

the controller as well as the 12V supply to drive the power

MOSFET, allowing a low cost N channel MOSFET

switch to be used. The IC also includes an error com-

parator for fast transient response, a precise voltage ref-

erence for setting the output voltage as well as a direct

drive of the MOSFET for the minimum part count.

FEATURES

FEATURES

LDO Controller allows the use of a low cost

pass transistor for the I/O supply

8 pin SOIC combines switching and linear

controller

Internal Pre-regulator Eliminates Cross talk

between Switching & Linear regulators

Automatic shut down of the linear regulator

when connected to the Vcc2 Det pin

On board MOSFET driver

Fastest transient response of any controller

method. ( 0 to 100% Duty Cycle in 100 nS )

1% internal voltage reference

Internal Under Voltage Lockout protects

MOSFET during start-up

APPLICATIONS

APPLICATIONS

Dual supply low voltage processor applications,

such as: P55C

™,CYRIX M2™, POWER PC™ and

AMD K6

™

Simple 5V to 3.3V switcher for Pentium with AGP

or Pentium II

™ applications

PACKAGE ORDER INFORMATION

PACKAGE ORDER INFORMATION

3033app1-1.1

CPU

I / O

Vcc2 Det

Core

5V

5V

12V

Q1

C1

L1

C3

Q2

D1

C2

L2

R4

R5

C7

R6

R7

C6

R8

R3

C5

1

2

3

4

5

6

7

8

Drv1V12swVfb1 Vhyst

Gnd

Vfb2

Drv2

V12

US3033

D2

R10

C8

R9