Compensation; Figure 55. Single Hub Interface Reference Divider Circuit; Figure 56. Locally Generated Hub Interface Reference Dividers - Intel 815EG Design Manual

R
9.1.4

Compensation

Independent hub interface compensation resistors are used by the GMCH and ICH2 to adjust
buffer characteristics to specific board characteristics. Refer to the Intel
82815G/82815EG Graphics and Memory Controller Hub (GMCH) for use with the Universal
Socket 370 Datasheet and the Intel
I/O Controller Hub (ICH2-M) Datasheet for details on compensation. The resistive Compensation
(RCOMP) guidelines are as follows:
• RCOMP: Tie the HLCOMP pin of each component to a 40 Ω, 1% or 2% pull-up resistor (to
1.8 V) via a 10 mil-wide, 0.5 inch trace (targeted at a nominal trace impedance of 40 Ω). The
GMCH and ICH2 each require its own RCOMP resistor.

Figure 55. Single Hub Interface Reference Divider Circuit

Figure 56. Locally Generated Hub Interface Reference Dividers

®
Intel 815EG Chipset Platform Design Guide
®
300
GM CH
HUBREF
0.01 µF
1.85 V
300 Ω
GM CH
HUBREF
300 Ω
82801BA I/O Controller Hub (ICH2) and Intel
1.85 V
Ω
0.01 µF
300 Ω
0.1 µF
1.85 V
0.1 µF
0.1 µF
Hub Interface
®
815 Chipset Family:
®
82801BAM
ICH2
HUBREF
hub_IF_ref_div_1_815E_B0
300 Ω
ICH2
HUBREF
300 Ω
hub_IF_ref_div_2_B0
99