US3034
8 PIN PWM SWITCHER
CONTROLLER IC
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
PRELIMINARY DATASHEET
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.
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
TYPICAL APPLICATION
C8
8 7 6 5
SS CS+ CS- Gnd
C6
US3034
Drv V12 Vfb Vhyst
1 2 3 4
12V
C3
R1
L1
R3
C5
L2
R8
R7
R6
Vout
C7
Q2
C1
C2
C4
R2
D1
R5
3034app1-1.0
5V
R4
Typical application of US3034
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.
PACKAGE ORDER INFORMATION
TA (°C)
0 TO 70
Rev. 1.8
1/13/99
8 PIN PLASTIC
SOIC (S)
US3034CS
4-1
UNISEM [ UNISEM ]
