Gmch Agtl+ I/O Buffer Compensation; Figure 143. Gmch Havref Reference Voltage Generation Circuit; Figure 144. Gmch Hccvref Reference Voltage Generation Circuit; Figure 145. Gmch Hxrcomp And Hyrcomp Resistive Compensation - Intel 855GM Design Manual

Intel 855GM/GME Chipset Based System Power Delivery Guidelines

Figure 143. GMCH HAVREF Reference Voltage Generation Circuit

R1
49.9
1%
R2
100
1%

Figure 144. GMCH HCCVREF Reference Voltage Generation Circuit

R1
49.9
1%
R2
100
1%
13.5.3.2.

GMCH AGTL+ I/O Buffer Compensation

The HXRCOMP and HYRCOMP pins of the GMCH should each be pulled-down to ground with a 27.4
Ω ± 1% resistor. See Figure 145. The maximum trace length from pin to resistor should be less than 0.5
inches and should be 18-mil wide to achieve the Zo = 27.4 Ω target. Also, the routing for HRCOMP
should be at least 25 mils away from any switching signal.

Figure 145. GMCH HXRCOMP and HYRCOMP Resistive Compensation

270
+VCCP
GMCH_HAVREF
C1
1uF
+VCCP
GMCH_HCCVREF
C3
C1
1uF
0.1uF
HXRCOMP
27.4 Ω +/- 1%
GMCH
Y22
HAVREF
C3
0.1uF
GMCH
Y28
HCCVREF
27.4 Ω +/- 1%
®
Intel 855GM/855GME Chipset Platform Design Guide
HYRCOMP
R