AN011 Datasheet, PDF(1/5 Page) Analog Intergrations Corporation

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AN011 Datasheet, PDF (1/5 Pages) Analog Intergrations Corporation – cost-effective technique

AN011

A novel, cost-effective technique for converting

VRM8.X VID to VRM9.0 compatible VID

Abstract

Since AIC1569A has been designed to meet the

Pentium II Processor, the equipped voltage level

range is from 3.5V to 1.3V. As the trend of new

generation CPU core voltage decreasing goes on, the

only and also major problem of VID setting is the

mismatch with (the VID setting canât meet) the

requirement of the (these) new processors. However,

(Somehow,) this problem can be solved by adding a

simple circuit externally. Due to the overlap voltage

range between Socket A CPU and that provided by

AIC1569A, this method provides a cost-effective

solution for Socket A CPU.

VID Configuration

VID pins are used to set the voltage reference for CPU

core voltage. This is accomplished by a build-in

Digital-to-Analog converter in AIC1569A. There are 5

VID pins named from VID0 to VID4 comprising 32

selections of voltage level. On the other hand, VID

definition of Socket A CPU (AMD ThunderBird) also is

configured with 5 pins, named VIDx (x=0~4), to define

the voltage range from 1.85V to 1.1V. The following

table shows both the AIC1569A and ThunderBird CPU

voltage levels versus VID setting.

VID[3:0]

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

1011

1100

1101

1110

1111

VCORE (VID4=0)

Socket A AIC1569A keep

1.850

2.05

2.050

1.825

2.00

2.000

1.800

1.95

1.950

1.775

1.90

1.900

1.750

1.85

1.850

1.725

1.80

1.800

1.700

1.75

1.750

1.675

1.70

1.700

1.650

1.65

1.650

1.625

1.60

1.600

1.55

1.550

1.575

1.50

1.500

1.550

1.45

1.450

1.525

1.40

1.400

1.500

1.35

1.350

1.475

1.30

1.300

VCORE (VID4=1)

Socket A AIC1569A redefine

1.450

3.5

2.075

1.425

3.4

2.025

1.400

3.3

1.975

1.375

3.2

1.925

1.350

3.1

1.875

1.325

3.0

1.825

1.300

2.9

1.775

1.275

2.8

1.725

1.250

2.7

1.675

1.225

2.6

1.625

1.200

2.5

1.575

1.175

2.4

1.525

1.150

2.3

1.475

1.125

2.2

1.425

1.100

2.1

1.375

No CPU

1.325

By comparing the voltage values in the table, 2

problems are found in the VID mismatch condition.

July 2000

First, voltage range of AIC1569A can not cover the

range of Socket A CPU, as mentioned above. Second,

▷