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AMD GeodeTM SP4SC40
System Platform
27 MHz Crystal Solutions

1.0 Scope
In silicon revision A3 (and earlier) of the AMD GeodeTM Rework Option #2: (TH oscillator):
SC1100 processor, a known issue (issue #6.7) exists Remove the 27 MHz crystal and associated components,
regarding the 27 MHz on-chip amplifier. This document dis- and add a half-size (8-pin DIP) square can oscillator.
cusses rework options for the AMD GeodeTM SP4SC40
system platform boards shipped with silicon revision A3 (or Wire pin 5 of the oscillator to pin 1 (farthest from processor)
earlier) of the SC1100 processor. This issue does not exist of Y1 (crystal footprint).
in silicon revision B1 of the SC1100 processor. Wire pins 1 and 8 of the oscillator to pin 3 of D4 (FET) for
VIO power connection.

2.0 Discussion Wire pin 4 of the oscillator to pin 2 of C122 for ground con-
nection.
The 27 MHz on-chip amplifier is too sensitive to the clock
waveform generated by the external crystal oscillator cir- No load R87, R91, C106, and C117.
cuit. Jitter of the 27 MHz clock signal can result in system Add a 0.1