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11.8.8
VBIAS DC Voltage and Noise Measurements
• All RTC OSC signals (RTCX1, RTCX2, VBIAS) should all be routed with trace lengths less
than 1 inch. The shorter, the better.
• Steady-state VBIAS is a DC voltage of about 0.38 V ± .06 V.
• When the battery is inserted, VBIAS will be "kicked" to about 0.7–1.0 V, but it will return to
its DC value within a few ms.
• Noise on VBIAS must be kept to a minimum (200 mV or less).
• VBIAS is very sensitive and cannot be directly probed, but it can be probed through a .01 µF
capacitor.
• Excessive noise on VBIAS can cause the ICH2 internal oscillator to misbehave or even stop
completely.
• To minimize VBIAS noise, it is necessary to implement the routing guidelines described
previously as well as the required external RTC circuitry, as described in the Intel
I/O Controller Hub (ICH2) and Intel
11.9
LAN Layout Guidelines
The ICH2 provides several options for integrated LAN capability. The platform supports several
components, depending on the target market. These guidelines use the 82562ET to refer to both
the 82562ET and 82562EM. The 82562EM is specified in those cases where there is a difference.
Table 26. LAN Connect
LAN Connect Component
Intel 82562EM
Intel 82562ET
Intel 82562EH
Intel developed a dual footprint for 82562ET and 82562EH, to minimize the required number of
board builds. A single layout with the specified dual footprint allows the OEM to install the
appropriate LAN connect component to satisfy market demand. Design guidelines are provided for
each required interface and connection. Refer Figure 80 and table for the corresponding section of
the design guide.
®
Intel
815EG Chipset Platform Design Guide
®
82801BAM I/O Controller Hub (ICH2-M) Datasheet.
Connection
Advanced 10/100 Ethernet
10/100 Ethernet
1 Mb HomePNA* LAN
I/O Subsystem
®
82801BA
Features
AOL* & Ethernet 10/100 connection
Ethernet 10/100 connection
1 Mb HomePNA connection
131
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