Table 54. Bus Capacitance Reference Chart; Table 55. Bus Capacitance/Pull-Up Resistor Relationship - Intel 855PM Design Manual

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Table 54. Bus Capacitance Reference Chart

Device
ICH4-M
CK408
SO-
DIMMS
PCI
Slots
Bus
Trace
Length
in inches

Table 55. Bus Capacitance/Pull-Up Resistor Relationship

Physical Bus Segment Capacitance
®
Intel 855PM Chipset Platform Design Guide
# of Devices/ Capacitance Includes
Trace Length
1 Pin Capacitance
1 Pin Capacitance
2 Pin Capacitance (10 pF) + 1 inch worth of trace capacitance (2 pF/inch)
per SO-DIMM and 2 pF connector capacitance per SO-DIMM
3
2 Each PCI add-in card is allowed up to 40 pF + 3 pF per each connector
3
4
5
6
≥24 2 pF per inch of trace length
≥36
≥48
0 to 100 pF
100 to 200 pF
200 to 300 pF
300 to 400 pF
I/O Subsystem
Pull-Up Range (For Vcc = 3.3 V
8.2 k to 1.2 k
4.7 k to 1.2 k
3.3 k to 1.2 k
2.2 k to 1.2 k
Cap (pF)
12
10
28
42
86
129
172
215
258
48
72
96
203