US3034

4-1

Rev. 1.8

1/13/99

8 PIN PWM SWITCHER

CONTROLLER IC

TYPICAL APPLICATION

TYPICAL APPLICATION

Typical application of US3034

TA (°C)

8 PIN PLASTIC

SOIC (S)

0 TO 70

US3034CS

Notes: 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 US3034 IC provides an 8 pin low cost switching

controller with true short circuit protection all in a

compact 8 pin surface mount package, providing a

low cost switching solution for dual supply processor

applications that require switching regulator for the 3.3V

supply such as the applications with AGP on board.

Typically in these applications a dual supply regulator

converts 5V to 3.3V for I/O supply and a jumper pro-

grammable supply of 1.25V to 3.5V for CORE supply .

The IC uses an internal 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 chan-

nel MOSFET to be used. The IC also includes an error

comparator for fast transient response, a precise volt-

age reference for setting the output voltage as well as a

direct drive of the MOSFET for the minimum part count.

FEATURES

FEATURES

8 pin SOIC Switching Controller with

HICCUP Current Limiting Reduces Diode

Power Dissipation to Less than 1% of Normal

Operation

Soft Start Capacitor allows for smooth Output

Voltage ramp up

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

PRELIMINARY DATASHEET

3034app1-1.0

Vout

5V

C1

L1

C3

Q2

C2

L2

R4

C7

D1

R2

C4

R5

R1

12V

R3

C5

C8

1

2

3

4

5

6

7

8

Drv

V12

Vfb Vhyst

Gnd

CS-

CS+

SS

US3034

R8

R6

C6

R7