XO1.5 1.2V power sequencing ECO: Difference between revisions
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=Procedure= |
=Procedure= |
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# Remove R234 |
# Remove R234 (right next to RTC crystal). |
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# Lift PU7, pin 6 (near PL6) and tie it to PRE_MAIN_ON. |
# Lift PU7, pin 6 (near PL6) and tie it to PRE_MAIN_ON (pad of R234 closest to VX855). |
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# Tie the MAIN_ON (U3, pin 1) signal to +1.2V_GD (D12, cathode). |
# Tie the MAIN_ON (U3, pin 1) signal to +1.2V_GD (D12, cathode). |
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# Remove PR67 (This is a quick fix. Ideally, pin 2 of PQ20 should be lifted and tied to an inverted, high voltage version of PRE_MAIN_ON). |
# Remove PR67 (This is a quick fix. Ideally, pin 2 of PQ20 should be lifted and tied to an inverted, high voltage version of PRE_MAIN_ON). |
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Revision as of 00:28, 22 June 2009
Scope
This describes a change to early prototypes of the XO-1.5 motherboard. It fixes a problem with the sequencing of power supply turn-on to the VX855 chip.
This only applies to XO-1.5 A-phase (both A1 and A2) motherboards.
Procedure
- Remove R234 (right next to RTC crystal).
- Lift PU7, pin 6 (near PL6) and tie it to PRE_MAIN_ON (pad of R234 closest to VX855).
- Tie the MAIN_ON (U3, pin 1) signal to +1.2V_GD (D12, cathode).
- Remove PR67 (This is a quick fix. Ideally, pin 2 of PQ20 should be lifted and tied to an inverted, high voltage version of PRE_MAIN_ON).
Results
This page is still a scratchpad testing a hypothesis.
Done to: