Intel i7-950 AT80601002112AA User Manual

Product codes

AT80601002112AA

Datasheet

Electrical Specifications

2.1

Intel

QPI Differential Signaling

The processor provides an Intel QPI port for high speed serial transfer between other
Intel QPI-enabled components. The Intel QPI port consists of two unidirectional links
(for transmit and receive). Intel QPI uses a differential signalling scheme where pairs of
opposite-polarity (D_P, D_N) signals are used.

On-die termination (ODT) is provided on the processor silicon and termination is to V

Intel chipsets also provide ODT; thus, eliminating the need to terminate the Intel QPI
links on the system board.

Intel strongly recommends performing analog simulations of the Intel

QPI interface.

Figure 2-1

illustrates the active ODT. Signal listings are included in

Table 2-3

and

Table 2-4

. See

Chapter 5

for the pin signal definitions. All Intel QPI signals are in the

differential signal group.

2.2

Power and Ground Lands

For clean on-chip processor core power distribution, the processor has 210 VCC pads
and 119 VSS pads associated with V

; 8 VTTA pads and 5 VSS pads associated with

TTA

; 28 VTTD pads and 17 VSS pads associated with V

TTD

, 28 VDDQ pads and 17 VSS

pads associated with V

DDQ

; and 3 VCCPLL pads. All VCCP, VTTA, VTTD, VDDQ and

VCCPLL lands must be connected to their respective processor power planes, while all
VSS lands must be connected to the system ground plane. The processor VCC lands
must be supplied with the voltage determined by the processor Voltage IDentification
(VID) signals.

Table 2-1

specifies the voltage level for the various VIDs.

2.3

Decoupling Guidelines

Due to its large number of transistors and high internal clock speeds, the processor is
capable of generating large current swings between low and full power states. This may
cause voltages on power planes to sag below their minimum values if bulk decoupling is
not adequate. Larger bulk storage (C

BULK

), such as electrolytic capacitors, supply

current during longer lasting changes in current demand; such as, coming out of an idle
condition. Similarly, capacitors act as a storage well for current when entering an idle
condition from a running condition. Care must be taken in the baseboard design to

Figure 2-1. Active ODT for a Differential Link Example

Signal