Design Guide

Platform Design Checklist
R
Intel
®
855GM/855GME Chipset Platform Design Guide 311
16.7.15. ICH4-M Decoupling Recommendations
Pin Name Configuration Value Q Notes
9
VCC1.5 Connect to Vcc1_5 0.1 µF 2 Low frequency decoupling is dependent on layout and
power supply design. CRB uses one 22 µF and one 100
µF.
VCC3.3 Connect to Vcc3_3 0.1 µF 6 Low frequency decoupling is dependent on layout and
power supply design. CRB uses two 22 µF.
VCCSUS1.5 Connect to
V1_5ALWAYS
0.1 µF 2 Low frequency decoupling is dependent on layout and
power supply design. CRB uses one 10 µF.
VCCSUS3.3 Connect to
V3ALWAYS
0.1 µF 2 Low frequency decoupling is dependent on layout and
power supply design. CRB uses one 22 µF.
VCCLAN1.5 Connect to
VccSus1_5
0.1 µF 2 Low frequency decoupling is dependent on layout and
power supply design. CRB uses one 22 µF.
VCCLAN3.3 Connect to
VccSus3_3
0.1 µF
4.7 µF
2
1
Low frequency decoupling is dependent on layout and
power supply design. CRB uses one 22 µF.
VCC5REF Connect to Vcc5
through 1 k
Ω
0.1 µF
1 µF
1
1
Caps from VCC5REF to ground. Also connect diode from
VCC5REF to Vcc3_3.
VCC5REFSUS Connect to
V5ALWAYS through
1 k
Ω
0.1 µF
1 µF
1
1
Caps from VCC5REFSUS to ground. Also connect diode
from VCC5REFSUS to V3ALWAYS.
VCC_CPU_IO Connect to VCCP 0.1 µF
1 µF
1
1
VCCPLL Connect to Vcc1_5 0.1 µF
0.01 µF
1
1
VCCRTC Connect to VccRTC 0.1 µF 1
VCCHI Connect to Vcc1_5 0.1 µF 2 Low frequency decoupling is dependent on layout and
power supply design. CRB uses one 22 µF.
NOTE: All decoupling guidelines are recommendations based on our reference board design. Customers will need to take their
layout, & PCB board design into consideration when deciding on their overall decoupling solution. Capacitors should be
place less than 100 mils from the package
16.8. USB Power Checklist
16.8.1. Downstream Power Connection
Pin Name Notes
9
USB_VCC[E:A] One 220 µF and two 470 pF are recommended for every two power lines. Either a
thermister or a power distribution switch (with short circuit and thermal protection) is
required.
See Figure 158.