IRU3027

Rev. 1.5

07/17/02

www.irf.com

TYPICAL APPLICATION

DESCRIPTION

The IRU3027 controller IC is specifically designed to meet

VRM 9.0 specification for next generation microproces-

sor applications requiring multiple on-board regulators.

The IRU3027 provides a single chip controller IC for the

Vcore, three LDO controllers, one with an automatic se-

lect pin that connects to the Type Detect pin of the AGP

slot for the AGP V

DDQ

supply, one for GTL+ and the other

for the 1.8V chip set regulator as required for the next

generation PC applications. The IRU3027 is designed to

use either bipolar transistors for V

OUT

3(1.5V) and

OUT

4(1.8V). No external resistor divider is necessary

for any of the regulators. The switching regulator fea-

tures a patented topology that in combination with a few

external components as shown in the typical applica-

tion circuit, will provide well in excess of 20A of output

current for an on-board DC-DC converter while automati-

cally providing the right output voltage via the 5-bit inter-

nal DAC. The IRU3027 also features loss-less current

sensing for both switchers by using the R

DS(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 out-

puts is outside of a pre-programmed window.

Designed to meet VRM 9.0 specification for next

generation microprocessors

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 V

DDQ

Supply

Linear Regulator Controller On-Board for 1.5V

GTL+ Supply

Loss-less Short Circuit Protection for all Outputs

Synchronous operation allows maximum effi-

ciency

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

Over-Voltage Protection Circuitry protects the

switcher output and generates a fault output

PACKAGE ORDER INFORMATION

FEATURES

5-BIT PROGRAMMABLE SYNCHRONOUS BUCK CONTROLLER IC

WITH TRIPLE LDO CONTROLLER

APPLICATIONS

Total power solution for next generation Intel

processor application

AMD K7 Low Cost Solution

(

C) DEVICE PACKAGE

0 To 70 IRU3027CW 28-Pin Plastic SOIC WB

Data Sheet No. PD94146

Figure 1 - Typical application of IRU3027.

LINEAR

CONTROL

LINEAR

CONTROL

SWITCHER

CONTROL

IRU3027

OUT

LINEAR

CONTROL

OUT

3.3V

Rev. 1.5

07/17/02

IRU3027

www.irf.com

ELECTRICAL SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

V5 Supply Voltage .................................................... 7V

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

Storage Temperature Range ...................................... -65 To 150癈

Operating Junction Temperature Range ..................... 0 To 125癈

PACKAGE INFORMATION

28 PIN WIDE BODY PLASTIC SOIC (W)

Unless otherwise specified, these specifications apply over V12=12V, V5=5V and T

=0 to 70癈. Typical values refer

to T

=25癈. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient

temperature.

=80

C/W

Drive2

Fix

VID4
VID3
VID2

VID1
VID0

PGood

SEN

Select

Fault / Rt

SEN

Drive4

Gnd

Drive3

SEN

OCSet

PGnd

LGate

Phase

UGate

V12

TOP VIEW

Supply UVLO Section
UVLO Threshold-12V
UVLO Hysteresis-12V
UVLO Threshold-5V
UVLO Hysteresis-5V
Supply Current
Operating Supply Current

VID Section (Vcore only)
DAC Output Voltage (Note 1)
DAC Output Line Regulation
DAC Output Temp Variation
VID Input LO
VID Input HI
VID Input Internal Pull-Up
Resistor to V5
V

SEN

2 Voltage

PARAMETER SYM TEST CONDITION MIN TYP MAX UNITS

Switching Controllers; Vcore (V

SEN

1) and AGP (V

SEN

Supply Ramping Up

V12
V5

Select <0.8V
Select >2V

0.99Vs

0.6
4.4
0.3

0.1
0.5

1.5
3.3

1.01Vs

0.8

V
V
V
V

%
%

V
V

IRU3027

Rev. 1.5

07/17/02

www.irf.com

Note 1: Vs refers to the set point voltage given in Table 1.

Error Comparator Section
Input Bias Current
Input Offset Voltage
Delay to Outout
Current Limit Section
CS Threshold Set Current
CS Comp Offset Voltage
Hiccup Duty Cycle
Output Drivers Section
Rise Time
Fall Time
Dead Band Time Between
High Side and Synch Drive
(Vcore Switcher Only)
Oscillator Section (Internal)
Osc Frequency
1.8V Regulator (V

SEN

SEN

Voltage

SEN

Voltage

Input Bias Current
Output Drive Current
1.5V Regulator (V

SEN

SEN

Voltage

SEN

Voltage

Input Bias Current
Output Drive Current
Power Good Section
V

SEN

1 UV Lower Trip Point

SEN

1 UV Upper Trip Point

SEN

1 UV Hysterises

SEN

1 HV Upper Trip Point

SEN

1 HV Lower Trip Point

SEN

1 HV Hysterises

SEN

2 Trip Point

SEN

3 Trip Point

SEN

4 Trip Point

Power Good Output LO
Power Good Output HI
Fault (Overvoltage) Section
Core OV Upper Trip Point
Core OV Lower Trip Point
Fault Output HI
Soft-Start Section
Pull-Up Resistor to 5V

PARAMETER

SYM TEST CONDITION MIN TYP MAX UNITS

-2

-5

ns
ns
ns

KHz

V
V

V
V
V
V
V
V
V

V
V

V
V
V

100

200

70
70

200

217

1.800
1.800

1.500
1.500

0.90Vs
0.92Vs
0.02Vs
1.10Vs
1.08Vs
0.02Vs

1.100
2.560
0.920
1.320
0.920
1.140

0.4
4.8

1.17Vs
1.15Vs

DIFF

=10mV

Css=0.1

=3000pF

Rt=Open

=25

C, Drive4=V

SEN

=25

C, Drive3=V

SEN

1 Ramping Down

SEN

1 Ramping Up

SEN

1 Ramping Up

SEN

1 Ramping Down

Select <0.8V
Select >2V
Fix=Gnd
Fix=Open
Fix=Gnd
Fix=Open
R

=3mA

=5K, Pull-Up to 5V

SEN

1 Ramping Up

SEN

1 Ramping Down

Io=3mA

OCSet=0V, Phase=5V

Rev. 1.5

07/17/02

IRU3027

www.irf.com

This pin controls the gate of an external MOSFET for the AGP linear regulator.

Leaving this pin open provides fixed output voltages of the 1.5V and 1.8V for the #3 and

#4 linear regulators. When this pin is grounded the reference to the linear regulators are

set to 1.26V and therefore the output of the regulators can be programmed to any volt-

ages above the 1.26V using: V

OUT

= 1.26

(1 + R

TOP

BOT

)

Where:

TOP

=Top resistor connected from the output to the V

SENSE

BOT

=Bottom resistor connected from the V

SENSE

pin to ground.

This pin selects a range of output voltages for the DAC. When in the LOW state the

range is 1.3V to 2.05V and when it switches to HI state the range is 2V to 3.5V. This pin

is TTL compatible that realizes a logic "1" as either HI or Open. When left open, this pin

is pulled up internally by a 27K

resistor to 5V supply.

MSB input to the DAC that programs the output voltage. This pin is TTL compatible that

realizes a logic "1" as either HI or Open. When left open, this pin is pulled up internally by

a 27K

resistor to 5V supply.

Input to the DAC that programs the output voltage. This pin is TTL compatible that real-

izes a logic "1" as either HI or Open. When left open, this pin is pulled up internally by a

27K

resistor to 5V supply.

Input to the DAC that programs the output voltage. This pin is TTL compatible that real-

izes a logic "1" as either HI or Open. When left open, this pin is pulled up internally by a

27K

resistor to 5V supply.

LSB input to the DAC that programs the output voltage. This pin is TTL compatible that

realizes a logic "1" as either HI or Open. When left open, this pin is pulled up internally by

a 27K

resistor to 5V supply.

This pin is an open collector output that switches LO when any of the outputs are outside

of the specified under-voltage trip point. It also switches low when V

SEN

1 pin is more than

10% above the DAC voltage setting.

PIN DESCRIPTIONS

1.075

1.100

1.125

1.150

1.175

1.200

1.225

1.250

1.275

1.300

1.325

1.350

1.375

1.400

1.425

1.450

1.475

1.500

1.525

1.550

1.575

1.600

1.625

1.650

1.675

1.700

1.725

1.750

1.775

1.800

1.825

1.850

Table 1 - Set point voltage vs. VID codes.

PIN# PIN SYMBOL PIN DESCRIPTION

Drive2

Fix

VID4

VID3

VID2

VID1

VID0

PGood

IRU3027

Rev. 1.5

07/17/02

www.irf.com

This pin provides shutdown for all the regulators. A TTL compatible, logic level high applied

to this pin disables all the outputs and discharges the soft-start capacitor. The SD signal

turns off the synchronous allowing the body diode to conduct and discharge the output

capacitor.

This pin provides the feedback for the AGP linear regulator. The Select pin when con-

nected to the "Type Detect" pin of the AGP slot automatically selects the right voltage for

the AGP V

DDQ

This pin provides automatic voltage selection for the AGP switching regulator. When it is

pulled LO, the voltage is 1.5V and when left open or pulled to HI, the voltage is 3.3V.

This pin provides the soft-start for all the regulators. An internal current source charges an

external capacitor that is connected from this pin to ground which ramps up the outputs of

the regulators, preventing the outputs from overshooting as well as limiting the input cur-

rent. The second function of the Soft-Start cap is to provide long off time (HICCUP) for the

synchronous MOSFET during current limiting.

This pin has dual function. It acts as an output of the over-voltage protection circuitry or it

can be used to program the frequency using an external resistor . When used as a fault

detector, if any of the switcher outputs exceed the OVP trip point, the Fault pin switches

to 12V and the soft-start cap is discharged. If the Fault pin is to be connected to any

external circuitry, it needs to be buffered.

This pin provides the feedback for the linear regulator that its output drive is Drive4.

This pin controls the gate of an external MOSFET for the 1.8V chip set linear regulator.

This pin has no connection.

This pin serves as the ground pin and must be connected directly to the ground plane.

This pin controls the gate of an external transistor for the 1.5V GTL+ linear regulator.

This pin provides the feedback for the linear regulator that its output drive is Drive3.

5V supply voltage. A high frequency capacitor (0.1 to 1

F) must be placed close to this

pin and connected from this pin to the ground plane for noise free operation.

This pin provides the feedback for the synchronous switching regulator. Typically this pin

can be connected directly to the output of the switching regulator. However, a resistor

divider is recommended to be connected from this pin to V

OUT

1 and ground to adjust the

output voltage for any drop in the output voltage that is caused by the trace resistance.

The value of the resistor connected from V

OUT

1 to Fb1 must be less than 1000

This pin is internally connected to the under-voltage and over-voltage comparators sens-

ing the Vcore status. It must be connected directly to the Vcore supply.

This pin is connected to the Drain of the power MOSFET of the Core supply and it provides

the positive sensing for the internal current sensing circuitry. An external resistor pro-

grams the current sense threshold depending on the R

of the power MOSFET. An

external capacitor is placed in parallel with the programming resistor to provide high fre-

quency noise filtering.

This pin serves as the Power ground pin and must be connected directly to the ground

plane close to the source of the synchronous MOSFET. A high frequency capacitor (typi-

cally 1

F) must be connected from V12 pin to this pin for noise free operation.

Output driver for the synchronous power MOSFET for the Core supply.

This pin is connected to the Source of the power MOSFET for the Core supply and it

provides the negative sensing for the internal current sensing circuitry.

Output driver for the high side power MOSFET for the Core supply.

This pin is connected to the 12V supply and serves as the power Vcc pin for the output

drivers. A high frequency capacitor (typically 1

F) must be placed close to this pin and

PGnd pin and be connected directly from this pin to the ground plane for the noise free

operation.

PIN# PIN SYMBOL PIN DESCRIPTION

SEN

Select

Fault / Rt

SEN

Drive4

Gnd

Drive3

SEN

OCSet

PGnd

LGate

Phase

UGate

V12

协谢械泻褌褉芯薪薪褘泄 泻芯屑锌芯薪械薪褌: IRU3027

协谢械泻褌褉芯薪薪褘泄泻芯屑锌芯薪械薪褌: IRU3027