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®
®
Intel
Pentium
M Processor and Intel
Schematic Checklist
®
Table 97.
Intel
ICH3-S Schematic Checklist (Sheet 7 of 8)
Checklist Items
VBIAS
RTCRST
RTCX1
RTCX2
SMBDATA
SMBCLK
SMLINK[1:0]
SMBALERT#/
GPIO[11]
INTRUDER#
258
®
E7501 Chipset Platform
Recommendations
RTC Signals
Use one 0.047 µF capacitor.
• Connect a 32.768 kHz Crystal Oscillator
across these pins with a 10 M Ω resistor.
Decouple each signal using a 18 pF
capacitor.
• RTCX1 may optionally be driven by an
external oscillator instead of a crystal.
These signals are 1.8 V only, and must not
be driven by a 3.3 V source.
System Management Signals
• Connect SMBCLK to SMLink0 and
SMBDATA to SMLink1.
• Require external pull-up resistors,
dependant upon bus capacitance and
termination power plane.
See GPIO section when SMBALERT# is not
implemented.
10 k Ω ± 5% pull-up to VCCRTC (VBAT) if not
needed.
Comments
• For noise immunity on VBIAS
signal.
• Refer to
Figure
116.
Refer to
Section
9.6.8.
• The external circuitry shown in
Figure 116
is required to
maintain the accuracy of the
RTC.
• Refer to
Section
9.6.1.
• The circuitry is required
because the new RTC oscillator
is sensitive to step voltage
changes in VCCRTC and
VBIAS. A negative step on the
power supply of more than
100 mV may temporarily shut
off the oscillator for hundreds of
milliseconds.
• Refer to
Section 9.6.3
for
decoupling requirements.
• Refer to
Section
9.5.
• Value of pull-up resistors
determined by line load, from
Section
9.5.4.
Refer to
Section
9.6.8.
Design Guide
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