Intel 521 Data Sheet - Page 34

34

Datasheet

Electrical Specifications

2.13

GTL+ FSB Specifications

Termination resistors are not required for most GTL+ signals, as these are integrated into the

processor silicon.Valid high and low levels are determined by the input buffers which compare a

signal’s voltage with a reference voltage called GTLREF.

Table 2-18

lists the GTLREF

specifications. The GTL+ reference voltage (GTLREF) should be generated on the system board

using high precision voltage divider circuits.

§

Table 2-18. GTL+ Bus Voltage Definitions

Symbol

Parameter

Min

Typ

Max

Units

Notes

1

NOTES:

1.

Unless otherwise noted, all specifications in this table apply to all processor frequencies.

GTLREF

Bus Reference

Voltage

(0.98 * 0.67) * V

TT

0.67 * V

TT

(1.02 * 0.67) * V

TT

V

2, 3, 4,

5

2.

The tolerances for this specification have been stated generically to enable the system designer to calculate the minimum

and maximum values across the range of V

TT

.

3.

GTLREF should be generated from V

TT

by a voltage divider of 1% resistors or 1% matched resistors.

4.

The V

TT

referred to in these specifications is the instantaneous V

TT

.

5.

The Intel

®

915G/915GV/915P and 910GL Express chipset platforms use a pull-up resistor of 100

Ω

and a pull-down resistor

of 210

Ω

. Contact your Intel representative for further details and documentation.

R

PULLUP

On die pullup for

BOOTSELECT

signal

500

—

5000

Ω

6

6.

These pull-ups are to V

TT

.

R

TT

Termination

Resistance

54

60

66

Ω

7

7.

R

TT

is the on-die termination resistance measured at V

TT

/2 of the GTL+ output driver.

COMP[1:0]

COMP Resistance

59.8

60.4

61

Ω

8

8.

COMP resistance must be provided on the system board with 1% resistors. COMP[1:0] resistors are to V

SS

.

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 34

GTL+ FSB Specifications

Page 34 highlights