Platform Design Checklist
R
276
Intel
®
855PM Chipset Platform Design Guide
14.2. Customer
Implementation
Fill in Schematic Name of Voltage Rails on Mark Boxes of when Rails are powered on.
Name of Rail
On S0-S1
On S3
On S4
On S5
14.3.
Design Checklist Implementation
The voltage rail designations in this design checklist were intended to be as general as possible. The
following table describes the equivalent voltage rails in the Intel CRB schematics attached in this design
guide.
Checklist Rail
Intel CRB Rail
On S0-S1
On S3
On S4
On S5
Vcc1_2[Vcc_mch] V1.2S_MCH X
Vcc1_25[DDR_Vtt]
4
V1.25S X
Vcc1_5 V1.5S,
1.5S_AGP
X
VccSus1_5 V1.5,
V1.5ALWAYS
X
X
1,3
1,3
V1_5ALWAYS See
VccSus1_5
X
X
X
X
Vcc1_8 V1-8S
X
VccSus2_5 V2.5_MCH,
V2.5DDR
X X
Vcc3_3 V3S,
V3.3S_ICH
X
VccSus3_3
V3, V3ALWAYS
X
X
1, 3
1, 3
VccSus3_3LAN V3.3_LAN X
2
2
2
V3ALWAYS See
VccSus3_3
X
X
X
X
Vcc5 V5S
X
VccSus5 V5
X
X
1
1
Vcc12 V12S
X
VccRTC VccRTC
X
X
X
X
VCCP
5
VCCP X
VCC[Vcc_Core] Vcc_core X
NOTES:
1.
A rail powered in Sx is dependent on implementation.
2.
A VccLANx rail powered on in Sx is dependent on implementation.
3.
A VxALWAYS rail can be the SUS rail depending on implementation.
4.
Vcc1_25 is the 1.25V VTT termination voltage for DDR. This power rail can be OFF during S3.
5.
VCCP is the 1.05V FSB signaling level of the CPU, MCH, and ICH4-M (legacy signal). Also used for the ITP700
FLEX debug port, if used.