US3012/3012A
5 BIT PROGRAMMABLE SYNCHRONOUS BUCK
CONTROLLER IC
PRELIMINARY DATASHEET
FEATURES
Dual Layout Compatible with RC5051
Designed to meet Intel specification of VRM8.2
& VRM8.3 for Pentium II™
On board DAC programs the output voltage
from 1.3V to 3.5V (US3010) & 1.8V to 3.5V for
US3010A
Loss less Short Circuit Protection
Synchronous operation allows maximum
efficiency
Patented architecture allows fixed frequency
operation as well as 100% duty cycle during
dynamic load
Soft Start
High current totem pole driver for direct
driving of the external Power MOSFET
Power Good function
DESCRIPTION
The US3012 family of controller ICs are specifically de-
signed to meet Intel specification for Pentium II™ and
Pentium Pro™ microprocessor applications as well as
the next generation P6 family processors. These prod-
ucts feature a patented topology that in combination
with a few external components as shown in the typical
application circuit below ,will provide in excess of 16A
of output current for an on- board DC/DC converter while
automatically providing the right output voltage via the 5
bit internal DAC .These devices also feature,
loss less
current sensing by using the Rds-on of the high side
Power MOSFET as the sensing resistor,
a Power Good
window comparator that switches its open collector out-
put low when the output is outside of a
±10%
window .
Other features of the device are ; Undervoltage lockout
for both 5V and 12V supplies as well as an external
programmable soft start function as well as program-
ming the oscillator frequency by using an external ca-
pacitor.
APPLICATIONS
Pentium II & Pentium Pro™ processor DC to DC
converter application
Low cost Pentium with AGP
TYPICAL APPLICATION
L1
L2
Q1
C5
C1
C3
R3
R5
Q2
R6
R2
R4
C7
C11
R7
R8
R9
5V
C4
C6
R10
R1
D1
R11
14
Vfb/
GndD
En 2
R12
R13
12V
13
V12
7 NC/Vccp
6
V5
4
CS+
12
HDrv
5
CS-
9
LDrv
10
Gnd
OutEn
Power Good
C9
C10
US3012
16 SS/Vref
C2
D4
8
D3
17
D2
18
D1
19
D0
20
NC/
GndP
11
NC/
GndA
15
PGd 3
Ct
1
C8
VID4
VID3
VID2
VID1
3012app1-1.1
VID0
Notes: Pentium II and Pentium Pro are
trade marks of Intel Corp.
PACKAGE ORDER INFORMATION
Ta (°C)
0 TO 70
0 TO 70
Rev. 1.0
5/6/98
Device
US3012CW
US3012ACW
Package
20 pin Plastic SOIC WB
20 pin Plastic SOIC WB
VID Voltage Range
1.3V to 3.5V
1.8V to 3.5V
4-1
UNISEM [ UNISEM ]
