Intel 521 Data Sheet - Page 17

Datasheet

17

Electrical Specifications

2.4

Voltage Identification

The VID specification for the Pentium 4 processor in the 775-land package is supported by the

Voltage Regulator Down (VRD) 10.1 Design Guide For Desktop LGA775 Socket

. The voltage set

by the VID signals is the reference VR output voltage to be delivered to the processor V

CC

pins. A

minimum voltage is provided in

Table 2-8

and changes with frequency. This allows processors

running at a higher frequency to have a relaxed minimum voltage specification. The specifications

have been set such that one voltage regulator can work with all supported frequencies.

Individual processor VID values may be calibrated during manufacturing such that two devices at

the same speed may have different VID settings.

The Pentium 4 processor in the 775-land package uses six voltage identification signals, VID[5:0],

to support automatic selection of power supply voltages.

Table 2-2

specifies the voltage level

corresponding to the state of VID[5:0]. A ‘1’ in this table refers to a high voltage level and a ‘0’

refers to low voltage level. If the processor socket is empty (VID[5:0] = x11111), or the voltage

regulation circuit cannot supply the voltage that is requested, it must disable itself. See the

Voltage

Regulator Down (VRD) 10.1 Design Guide For Desktop LGA775 Socket

for more details

.

Power source characteristics must be guaranteed to be stable when the supply to the voltage

regulator is stable.

The LL_ID[1:0] lands are used by the platform to configure the proper loadline slope for the

processor. LL_ID[1:0] = 00 for the Pentium 4 processor in the 775-land package.

The VTT_SEL land is used by the platform to configure the proper V

TT

voltage level for the

processor. VTT_SEL = 1 for the Pentium 4 processor in the 775-land package.

The GTLREF_SEL signal is used by the platform to select the appropriate chipset GTLREF level.

GTLREF_SEL = 0 for the Pentium 4 processor in the 775-land package.

LL_ID[1:0] and VTT_SEL are signals that are implemented on the processor package. That is,

they are either connected directly to V

SS

or are open lands.

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 17

Voltage Identification

Page 17 highlights