Intel 521 Data Sheet - Page 73

Datasheet

73

Land Listing and Signal Descriptions

§

VID[5:0]

Output

VID[5:0] (Voltage ID) signals are used to support automatic selection of power

supply voltages (V

CC

). These are open drain signals that are driven by the

processor and must be pulled up on the motherboard. Refer to the

Voltage

Regulator-Down (VRD) 10.1 Design Guide for Desktop Socket 775

for more

information. The voltage supply for these signals must be valid before the VR

can supply V

CC

to the processor. Conversely, the VR output must be disabled

until the voltage supply for the VID signals becomes valid. The VID signals are

needed to support the processor voltage specification variations. See

Table 2-2

for definitions of these signals. The VR must supply the voltage that is

requested by the signals, or disable itself.

VSS

Input

VSS are the ground pins for the processor and should be connected to the

system ground plane.

VSSA

Input

VSSA is the isolated ground for internal PLLs.

VSS_SENSE

Output

VSS_SENSE is an isolated low impedance connection to processor core V

SS

. It

can be used to sense or measure ground near the silicon with little noise.

VSS_MB_

REGULATION

Output

This land is provided as a voltage regulator feedback sense point for V

SS

. It is

connected internally in the processor package to the sense point land V27 as

described in the

Voltage Regulator-Down (VRD) 10.1 Design Guide for Desktop

Socket 775

.

VTT

Miscellaneous voltage supply.

VTT_OUT_LEFT

VTT_OUT_RIGHT

Output

The VTT_OUT_LEFT and VTT_OUT_RIGHT signals are included to provide a

voltage supply for some signals that require termination to V

TT

on the

motherboard.

For future processor compatibility some signals are required to be pulled up to

VTT_OUT_LEFT or VTT_OUT_RIGHT. Refer to the following table for the

signals that should be pulled up to VTT_OUT_LEFT and VTT_OUT_RIGHT.

VTT_SEL

Output

The VTT_SEL signal is used to select the correct V

TT

voltage level for the

processor.

VTTPWRGD

Input

The processor requires this input to determine that the V

TT

voltages are stable

and within specification.

Table 4-3. Signal Description

(Sheet 8 of 8)

Name

Type

Description

Pull-up Signal

Signals to be Pulled Up

VTT_OUT_RIGHT

VTT_PWRGOOD, VID[5:0], GTLREF, TMS, TDI,

TDO, BPM[5:0], other VRD components

VTT_OUT_LEFT

RESET#, BR0#, PWRGOOD, TESTHI1, TESTHI8,

TESTHI9, TESTHI10, TESTHI11, TESTHI12

Section	Page
Contents	3
Revision History	7
Intel® Pentium® 4 Processors 570/571, 560/561, 550/551, 540/541, 530/531, and 520/521	9
1 Introduction	11
1.1 Terminology	12
1.1.1 Processor Packaging Terminology	12
1.2 References	13
2 Electrical Specifications	15
2.1 FSB and GTLREF	15
2.2 Power and Ground Lands	15
2.3 Decoupling Guidelines	15
2.3.1 VCC Decoupling	16
2.3.2 FSB GTL+ Decoupling	16
2.3.3 FSB Clock (BCLK[1:0]) and Processor Clocking	16
2.4 Voltage Identification	17
2.4.1 Phase Lock Loop (PLL) Power and Filter	19
2.5 Reserved, Unused, FC and TESTHI Signals	20
2.6 FSB Signal Groups	21
2.7 GTL+ Asynchronous Signals	22
2.8 Test Access Port (TAP) Connection	23
2.9 FSB Frequency Select Signals (BSEL[2:0])	23
2.10 Absolute Maximum and Minimum Ratings	24
2.11 Processor DC Specifications	24
2.12 VCC Overshoot Specification	33
2.12.1 Die Voltage Validation	33
2.13 GTL+ FSB Specifications	34
3 Package Mechanical Specifications	35
3.1 Package Mechanical Drawing	35
3.2 Processor Component Keep-Out Zones	39
3.3 Package Loading Specifications	39
3.4 Package Handling Guidelines	39
3.5 Package Insertion Specifications	40
3.6 Processor Mass Specification	40
3.7 Processor Materials	40
3.8 Processor Markings	40
3.9 Processor Land Coordinates	41
4 Land Listing and Signal Descriptions	43
4.1 Processor Land Assignments	43
4.2 Alphabetical Signals Reference	66
5 Thermal Specifications and Design Considerations	75
5.1 Processor Thermal Specifications	75
5.1.1 Thermal Specifications	75
5.1.2 Thermal Metrology	79
5.2 Processor Thermal Features	79
5.2.1 Thermal Monitor	79
5.2.2 Thermal Monitor 2	80
5.2.3 On-Demand Mode	81
5.2.4 PROCHOT# Signal	82
5.2.5 THERMTRIP# Signal	82
5.2.6 TCONTROL and Fan Speed Reduction	82
5.2.7 Thermal Diode	83
6 Features	85
6.1 Power-On Configuration Options	85
6.2 Clock Control and Low Power States	85
6.2.1 Normal State	86
6.2.2 HALT and Enhanced HALT Powerdown States	86
6.2.2.1 HALT Powerdown State	86
6.2.2.2 Enhanced HALT Powerdown State	86
6.2.3 Stop-Grant State	87
6.2.4 Enhanced HALT Snoop or HALT Snoop State, Grant Snoop State	88
6.2.4.1 HALT Snoop State, Grant Snoop State	88
6.2.4.2 Enhanced HALT Snoop State	88
7 Boxed Processor Specifications	89
7.1 Mechanical Specifications	90
7.1.1 Boxed Processor Cooling Solution Dimensions	90
7.1.2 Boxed Processor Fan Heatsink Weight	91
7.1.3 Boxed Processor Retention Mechanism and Heatsink Attach Clip Assembly	91
7.2 Electrical Requirements	91
7.2.1 Fan Heatsink Power Supply	91
7.3 Thermal Specifications	93
7.3.1 Boxed Processor Cooling Requirements	93

Intel 521 Data Sheet - Page 73

Table 4-3. Signal Description, Sheet 8 of 8

Page 73 highlights