Intel 6300ESB ICH, Design Manual

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Intel
®
855GME Chipset and Intel
®
6300ESB ICH Embedded Platform Design Guide
Schematic Checklist Summary
12.4.9 System Management Checklist
12.4.10 RTC Checklist
Table 140. System Management Checklist
Checklist Items Recommendations Reason/Impact
SMBCLK, SMBDATA,
Typical value of pull-up resistors is 8.2 K
Ω
to VccSus3.3.
Value of pull-up resistors determined by
line load.
Connect SMLINK[0] to SMBCLK and
SMLINK[1] to SMBDATA
Requires external pull-up resistors.
Typical value and power well determined
by SMBus Architecture and Design
Consideration section.
Pull-up value also determined by bus
section characteristics. Additional
circuitry may be required to connect high
and low power sections.
In order to be fully compliant with the
SMBus 2.0 specification (which requires
the Host Notify cycle), the SMLink and
SMBus signals
must be tied together
externally. This recommendation
ensures proper functionality of the
SMBus 2.0/SMLink Interface for legacy
TCO and for cases when an external
ASF controller is used.
SMLINK[1:0]
Requires external 8.2 K
Ω
pull-up resistors
to VccSus3.3.
Connect SMLINK[0] to SMBCLK and
SMLINK[1] to SMBDATA
Value of pull-up resistors determined by
line load.
To be fully compliant with the
SMBus 2.0
specification (which requires the Host
Notify cycle), the SMLink and SMBus
signals
must be tied together externally.
This recommendation ensures proper
functionality of the SMBus 2.0/SMLink
Interface for legacy TCO and for cases
when an external ASF controller is used.
INTRUDER#
Pull signal to V
CC
RTC (VBAT) through a
1 M
Ω
signal.
SMBALERT#/
GPIO[11] See GPIO section when SMBALERT# not
implemented.
Table 141. RTC Checklist
Checklist Items Recommendations Reason/Impact
RTCRST#
Use a 20 K
Ω
pull-up resistor to VccRTC
and a 1.0 µF cap to ground.
Time constant due to RC filter on this line
should be 18-25 ms.
RTCX1,
RTCX2
Connect a 32.768 kHz Crystal Oscillator
across these pins with a 10 M
Ω
resistor.
See Section 9.11.2 for capacitor
guidelines.
The external circuitry shown in
Section 129 is required to maintain the
RTC’s accuracy. 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.
VBIAS
Ensure the VBIAS pin of the 6300ESB is
connected to Vbatt through a 0.047 µF
cap. (See Section 9.11.6 .)
For noise immunity on VBIAS signal.