Specifications

Intel
®
810E2 Chipset Platform
R
Design Guide
169
7.2.11. System Management
Checklist
Items
Recommendations
SMBDATA
SMBCLK
Requires external pull-up resistors. See SMBus Architecture and Design Consideration section
to determine the appropriate power well to use to tie the pull-up resistors. (Core well, suspend
well, or a combination.)
Value of pull-up resistors determined by line load. Typical value used is 8.2 k
Ω.
SMBALERT#/
GPIO[11]
See GPIO section if SMBALERT# not implemented
SMLINK[1:0] Requires external pull-up resistors. See SMBus Architecture and Design Consideration section
to determine the appropriate power well to use to tie the pull-up resistors. (Core well, suspend
well, or a combination.)
Value of pull-up resistors determined by line load. Typical value used is 8.2 k
Ω.
INTRUDER# Pull signal to VCCRTC (VBAT), if not needed.
7.2.12. ISA Bridge Checklist
Checklist
Items
Recommendations
ICH2 GPO[21] /
MISA NOGO
input
Connect ICH2 GPO[21] to MISA NOGO input.
If GPO[21] is not available on the ICH2, any other GPO that defaults High in the system can
be used. GPO[21] is the only ICH2 GPO that defaults high.
ICH2 AD22 /
MISA IDSEL
input
Connect ICH2 AD22 to the MISA IDSEL input.
7.2.13. RTC
Checklist
Items
Recommendations
VBIAS The VBIAS pin of the ICH2 is connected to a .047 µF cap. See Figure 86
RTCX1
RTCX2
Connect a 32.768 kHz Crystal Oscillator across these pins with a 10 MΩ resistor and use 18
pF decoupling caps (assuming crystal with CLOAD=12.5 pF) at each signal.
The ICH2 implements a new internal oscillator circuit as compared with the PIIX4 to reduce
power consumption. The external circuitry shown in Figure 86 will be required to maintain the
accuracy of the RTC.
The circuitry is required since the new RTC oscillator is sensitive to step voltage changes in
VCCRTC and VBIAS. A negative step on power supply of more than 100 mV will temporarily
shut off the oscillator for hundreds of milliseconds.
RTCX1 may optionally be driven by an external oscillator instead of a crystal. These signals
are 1.8V only, and must not be driven by a 3.3V source.
RTCRST# Ensure 10 ms-20 ms RC delay (8.2 K & 2.2 µF) See Figure 43. RTCRST External Circuit for
Intel
®
ICH2 RTC
SUSCLK To assist in RTC circuit debug, route SUSCLK to a test point if it is unused.