UNISEM US3027CW Datasheet

5 BIT PROGRAMMABLE SYNCHRONOUS BUCK

FEATURESFEATURES

Designed to meet VRM 9.0 specification for
next generation micrprocessors
On board 5 bit DAC programs the output
voltage from 1.075V to 1.850V in 25mV steps
Linear regulator controller on board for 1.8V
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 1.5V
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

APPLICATIONSAPPLICATIONS

Total Power Soloution for Next Generation Intel
Processor application
AMD K7 Low Cost Solution

US3027

PLUS TRIPPLE LDO CONTROLLER

PRELIMINARY DATASHEET

DESCRIPTIONDESCRIPTION

The US3027 controller IC is specifically designed to meet
VRM 9.0 specification for next generation microproces­sor applications requiring multiple on board regulators .

The US3027 provides a single chip controller IC for
the Vcore , 3LDO controllers, one with the auto­matic select pin that connects to the TYPE DETECT
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 US3027 is designed to use either Bipolar
transistors for Vout3(1.5V) and Vout4(1.8V) or if Vaux
pin is connected to 12V, then MOSFETs can also be
used as external pass elements. No external resis­tor divider is necessary 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 application circuit ,will provide well in ex­cess of 20A of output current for an on- board DC/DC
converter while automatically providing the right output
voltage via the 5 bit internal DAC .The US3027 also fea­tures, loss less current sensing for both switcher by

using the Rds-on of the high side Power MOSFET
as the sensing resistor, an output under voltage
shutdown that detects short circuit condition for the
linear outputs and latches the system off, and a

Power Good window comparator that switches its open
collector output low when any one of the outputs is out­side of a pre programmed window.

TYPICAL APPLICATIONTYPICAL APPLICATION

5V

3.3V

Vout2

Vout3

LINEAR

CONTROL

US3027

LINEAR

CONTROL

PACKAGE ORDER INFORMATIONPACKAGE ORDER INFORMATION

Ta (°C) Device Package

0 TO 70 US3027CW 28 pin Plastic SOIC WB

Rev. 1.3
12/8/00

SWITCHER

CONTROL

LINEAR

CONTROL

3027app3-1.0

Vout1

Vout4

4-1

US3027

ABSOLUTE MAXIMUM RATINGSABSOLUTE MAXIMUM RATINGS

V5 supply Voltage ........................................... 7V

V12 Supply Voltage ............................................ 20V

Storage Temperature Range ................................. -65 TO 150°C

Operating Junction Temperature Range .......... 0 TO 125°C

PACKAGE INFORMATIONPACKAGE INFORMATION

28 PIN WIDE BODY PLASTIC SOIC (W)

TOP VIEW

1

Drive2

2

Fix

3

VID4

4

VID3

5

VID2

6

VID1

7

VID0

8 21

PGood

9 20

SD

10 19

Vsen2

11 18

Select

12 17

SS

13 16

Fault / Rt

14

Vsen4 Drive4

28
27
26
25
24
23
22

15

V12
UGate
Phase
LGate
PGnd
OCSet
Vsen1
Fb
V5
Vsen3
Drive3
Gnd
NC

θJA =80°C/W

ELECTRICAL SPECIFICATIONSELECTRICAL SPECIFICATIONS

Unless otherwise specified ,these specifications apply over ,V12 = 12V, V5 = 5V and Ta=0 to 70°C. Typical values
refer to Ta =25°C. Low duty cycle pulse testing are used which keeps junction and case temperatures equal to the
ambient temperature.

PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS
Supply UVLO Section

UVLO Threshold-12V Supply ramping up 10 V
UVLO Hysterises-12V 0.6 V
UVLO Threshold-5V Supply ramping up 4.4 V
UVLO Hysterises-5V 0.3 V

Supply Current

Operating Supply Current

V12 6 mA

V5 30

Switching Controllers; Vcore (Vsen 1) and AGP (Vsen 2)
VID Section (Vcore only)

DAC output voltage (note 1) 0.99Vs Vs 1.01Vs V
DAC Output Line Regulation 0.1 %
DAC Output Temp Variation 0.5 %
VID Input LO 0.8 V
VID Input HI 2 V
VID input internal pull-up
resistor to V5 27 kΩ
Vsen2 Voltage Select<0.8V 1.5 V

Select>2V 3.3 V

4-2

Rev. 1.3

12/8/00

US3027

Error Comparator Section

Input bias current 2 uA
Input Offset Voltage -2 +2 mV
Delay to Output Vdiff=10mV 100 nS

Current Limit Section

C.S Threshold Set Current 200 uA
C.S Comp Offset Voltage -5 +5 mV
Hiccup Duty Cycle Css=0.1 uF 10 %

Output Drivers Section

Rise Time CL=3000pF 70 nS
Fall Time CL=3000pF 70 nS
Dead band Time Between
High side and Synch Drive
(Vcore Switcher Only) CL=3000pF 200 nS

Oscillator Section (internal)

Osc Frequency Rt=Open 217 Khz

1.8V Regulator (Vsen 4)

Vsense Voltage Vo4 Ta=25, Drive4 = Vsen4 1.800 V
Vsense Voltage 1.800 V
Input bias current 2 uA
Output Drive Current Vaux-Vdrive>0.6V 50 mA

1.5V Regulator (Vsen 3)

Vsense Voltage Vo3 Ta=25, Drive3 = Vsen3 1.500 V
Vsense Voltage 1.500 V
Input bias current 2 uA
Output Drive Current Vaux-Vdrive>0.6V 50 mA

Power Good Section

Vsen1 UV lower trip point Vsen1 ramping down 0.90Vs V
Vsen1 UV upper trip point Vsen1 ramping up 0.92Vs V
Vsen1 UV Hysterises .02Vs V
Vsen1 HV upper trip point Vsen1 ramping up 1.10Vs V
Vsen1 HV lower trip point Vsen1 ramping down 1.08Vs V
Vsen1 HV Hysterises .02Vs V
Vsen2 trip point Select<0.8V 1.100 V

Select>2V 2.560 V

Vsen4 trip point Fix=GND 0.920 V

Fix=Open 1.320 V

Vsen3 trip point Fix=GND 0.920 V

Fix=Open 1.140 V
Power Good Output LO RL=3mA 0.4 V
Power Good Output HI RL=5K pull up to 5V 4.8 V

Fault (Overvoltage) Section

Core O.V. upper trip point Vsen1 ramping up 1.17Vs V
Core O.V. lower trip point Vsen1 ramping down 1.15Vs V
FAULT Output HI Io=3mA 10 V

Soft Start Section

Soft Start Current OCset=0V , Phase=5V 20 uA

Rev. 1.3
12/8/00

4-3