US3021M
5 BIT PROGRAMMABLE SYNCHRONOUS BUCK
PLUS TRIPPLE LDO CONTROLLER
PRELIMINARY DATASHEET
FEATURES
Provides Single Chip Solution for Vcore,
GTL+ ,AGP Bus, and 1.8V
Automatic Voltage Selection for AGP slot
Vddq supply
Linear regulator controller on board for 1.8V
Designed to meet Intel Latest VRM specifica-
tion for next generation micrprocessors
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 for all
outputs
Synchronous operation allows maximum
efficiency
Patented architecture allows fixed frequency
operation as well as 100% duty cycle during
dynamic load
Minimum part count
Soft Start
High current totem pole driver for direct
driving of the external Power MOSFET
Power Good function Monitors all Outputs
OVP Circuitry Protects the Switcher Output
and generates a Fault output
DESCRIPTION
The US3021M controller IC is specifically designed to
meet Intel specification for next generation micropro-
cessor applications requiring multiple on board regula-
tors .
The US3021M provides a single chip control-
ler IC for the Vcore , 3LDO controllers, one with the
automatic select pin that connects to the TYPE DE-
TECT pin of the AGP slot for the AGP Vddq supply,
one for GTL+ and the other for the 1.8V chip set
regulator as required for the next generation PC
applications. The US3021M uses N ch MOSFET as
pass transistor for Vout2(Vddq), Vout3(1.5V) and
Vout4(1.8V). No external resistor divider is neces-
sary for any of the regulators.
The switching regulator
feature a patented topology that in combination with a
few external components as shown in the typical appli-
cation circuit ,will provide well in excess of 20A of out-
put current for an on- board DC/DC converter while auto-
matically providing the right output voltage via the 5 bit
internal DAC .The US3021M also features,
loss less cur-
rent sensing for both switcher by using the Rds-on
of the high side Power MOSFET as the sensing re-
sistor, an output under voltage shutdown that de-
tects short circuit condition for the linear outputs
and latches the system off, and
a Power Good win-
dow comparator that switches its open collector output
low when any one of the outputs is outside of a pre pro-
grammed window.
APPLICATIONS
Total Power Soloution for Next Generation Intel
Processor application
TYPICAL APPLICATION
5V
3.3V
LINEAR
CONTROL
SWITCHER
CONTROL
Vout1
Vout2
US3021M
LINEAR
CONTROL
Vout3
LINEAR
CONTROL
Vout4
3021Mapp3-1.1
PACKAGE ORDER INFORMATION
Ta (°C)
0 TO 70
Rev. 1.3
12/8/00
Device
US3021MCW
Package
28 pin Plastic SOIC WB
4-1
UNISEM [ UNISEM ]
