XO1.5 1.2V power sequencing ECO: Difference between revisions
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(New page: =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-...) |
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This page is still a scratchpad testing a hypothesis. |
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Revision as of 03:31, 20 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. Use one pad to provide PRE_MAIN_ON.
- Lift PU7, pin 6 (near PL6) and tie it to PRE_MAIN_ON.
- Tie the MAIN_ON signal to +1.2V_GD.
- 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: