Motherboard Implementation - Intel 855GME Design Manual

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Intel 855GME Chipset and Intel
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Intel 6300ESB Design Guidelines
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All resistors in the signal path or on the voltage reference should be metal film. Carbon
resistors may be used for DC voltages and the power supply path, where the voltage
coefficient, temperature coefficient, and noise are not factors.
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Regions between analog signal traces should be filled with copper, which should be
electrically attached to the analog ground plane. Regions between digital signal traces should
be filled with copper, which should be electrically attached to the digital ground plane
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Locate the crystal or oscillator close to the codec.
9.4.2

Motherboard Implementation

The following design considerations are provided for the implementation of an 6300ESB using
AC'97. These design guidelines have been developed to ensure maximum flexibility for board
designers, while reducing the risk of board-related issues. These recommendations are not the only
implementation or a complete checklist, but they are based on the 6300ESB.
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Active Components such as FET switches, buffers or logic states should not be implemented
on the AC-link signals, except for AC_RST#. Doing so would potentially interfere with timing
margins and signal integrity.
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The 6300ESB supports wake-on-ring from S1-S5 states through the AC'97 link. The codec
asserts AC_SDIN to wake the system. To provide wake capability and/or caller ID, standby
power must be provided to the modem codec. In this case, the modem codec may be powered
by either its own or an external clock source. When no codec is attached to the link, internal
pull-downs will prevent the inputs from floating, so external resistors are not required.
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PC_BEEP should be routed through the audio codec. Care should be taken to avoid the
introduction of a pop when powering the mixer up or down.
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6300ESB ICH Embedded Platform Design Guide