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Platform Design Checklist
R
Intel
®
855PM Chipset Platform Design Guide
323
14.8.15. ICH4-M Power Signals & Decoupling Recommendations
ICH4-M – Power Signals & Decoupling Recommendations
1,2
Pin Name
System
Pull up/Pull down
Notes
9
VCC1.5[15:0]
Tie to Vcc1_5
Two 0.1 µF capacitors (place near balls: K23 and C23)
are required for decoupling.
VCC3.3[15:0]
Tie to Vcc3_3
Six 0.1 µF capacitors (place near ball : A1, A4, H1, T1,
AC10, and AC18) are required for decoupling.
VCCSUS1.5[7:0]
Tie to V1_5ALWAYS
Two 0.1 µF capacitors (place near balls: A16 and AC1)
are required for decoupling.
VCCSUS3.3[9:0]
Tie to V3ALWAYS
Two 0.1 µF capacitors (place near ball: A22 and AC5)
are required for decoupling.
VCCLAN1.5[1:0]
Tie to VccSus1_5
Two 0.1 µF capacitors (place near ball: F6 and F7) are
required for decoupling.
VCCLAN3.3[1:0]
Tie to VccSus3_3
Two 0.1 µF capacitors (place near ball: E9 and F9) are
required for decoupling.
VCC5REF[2:1]
Tie to Vcc5
1 k
One 0.1 µF capacitor (place near ball: E7) is required
for decoupling.
VCC5REFSUS1 See
Notes
One 0.1 µF capacitor (place near ball: A16) is required
for decoupling.
If Wake on USB from S3 and self-powered USB
devices are supported:
Tie to V5ALWAYS
If Wake on USB from S3 and self-powered USB
devices are NOT supported:
Tie to a combination of V3ALWAYS and Vcc5 or
VccSus5. See Section 11.4.1.3 for more details.
VCC_CPU_IO[2:0]
Tie to VCCP
One 0.1 µF capacitor (place near ball: AA23) is
required for decoupling.
VCCPLL
Tie to Vcc1_5
One 0.1 µF and one 0.01 uF capacitors (place near ball
C22) are required for decoupling.
VCCRTC
Tie to Vcc_RTC
One 0.1 µF capacitor (place near ball: AB5) is required
for decoupling.
VCCHI[3:0]
Tie to Vcc1_8
Two 0.1 µF capacitors (place near balls: T23 and N23)
are required for decoupling.
NOTES:
1.
All decoupling guidelines are recommendations based on our reference board design. Customers will need to take their layout,
and PCB board design into consideration when deciding on their overall decoupling solution
2.
Capacitors should be place less than 100 mils from the package