Separate Gmch And Ich4-M Voltage Generation / Separate Divider Circuits For Vref And Vswing; Hub Interface Decoupling Guidelines; Figure 91. Individual Hivref And Hi_Vswing Voltage Reference Divider Circuits For Ich4-M And Gmch; Table 84. Recommended Resistor Values For Hivref And Hi_Vswing Divider Circuits For Ich4-M - Intel 855GM Design Manual

R
10.3.4. Separate GMCH and ICH4-M Voltage Generation / Separate
Divider Circuits for VREF and VSWING
This option allows for tuning the voltage references HIVREF and HI_VSWING individually, for both
ICH4-M and GMCH. The reference voltage for both HIVREF and HI_VSWING must meet the voltage
specification in Table 81. Normal care needs to be taken to minimize crosstalk to other signals (< 10-15
mV). Note that resistor values used for 855GM chipset GMCH and 855GME chipset GMCH are
different since Vcc GMCH is different.
Figure 91. Individual HIVREF and HI_VSWING Voltage Reference Divider Circuits for ICH4-M and
GMCH

Table 84. Recommended Resistor Values for HIVREF and HI_VSWING Divider Circuits for ICH4-M

Chipset
Component
ICH4-M
855GM
855GME
10.4.

Hub Interface Decoupling Guidelines

See Section 13.5.5 for more details.
®
Intel 855GM/855GME Chipset Platform Design Guide
V GMCH
CC
R8
PSWING
HLVREF
GMCH
R9
C6
C5
Signal Recommended Resistor
Values
R4 = 487 Ω ± 1%
HIVREF
(350mV)
R5 = 150 Ω ± 1%,
R6 = 130 Ω ± 1%
HI_VSWING
(800mV)
R7 = 150 Ω ± 1%,
R8 = 243 Ω ± 1%
HLVREF
(350mV)
R9 = 100 Ω ± 1%
R10 = 49.9 Ω ± 1%
PSWING
(800mV)
R11 = 100 Ω ± 1%
R8 = 287 Ω ± 1%
HLVREF
(350mV)
R9 = 100 Ω ± 1%
R10 = 68.1 Ω ± 1%
PSWING
(800mV)
R11 = 100 Ω ± 1%
R10
HI_VSWING
HIVREF
ICH4-M
R11
C3 C1
VCCHI
VCCHI=1.5 V
VCCHI=1.5 V
VCCGMCH=1.2 V
VCCGMCH=1.2 V
VCCGMCH=1.35 V
VCCGMCH=1.35 V
Hub Interface
V HI
CC
R6
R4
R7
R5
C2
C4 C3 C1
Capacitor value
C3 = 0.1 µF (near divider)
C2 = 0.01 µF (near component)
C1 = 0.1 µF (near divider)
C4 = 0.01 µF (near component)
C3 = 0.1 µF (near divider)
C6 = 0.01 µF (near component)
C1 = 0.1 µF (near divider)
C5 = 0.01 µF (near component)
C3 = 0.1 µF (near divider)
C6 = 0.01 µF (near component)
C1 = 0.1 µF (near divider)
C5 = 0.01 µF (near component)
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