XO1.5 1.2VSUS 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, which preve...) |
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=Procedure= |
=Procedure= |
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# Cut trace between PU5, pin 3 and |
# Cut trace between PU5, pin 3 and +1.8VSUS near C355 (keeping PC54 connected to pin 3). |
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# Run wire from PU5, pin 3 to 3VPCU |
# Run wire from PU5, pin 3 to 3VPCU (anode of D19, next to Q22) |
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# Cut trace at top of PR70, and tie to |
# Cut trace at top of PR70, and tie to 3VPCU (at PU5, pin 3 or PC54). |
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# Lift Q22, pin 1 emitter, removing it from the VR_ON net. Tie Q22, pin 1 to +1.2VSUS_GD (PU5, pin 1 or PR70). |
# Lift Q22, pin 1 emitter, removing it from the VR_ON net. Tie Q22, pin 1 to +1.2VSUS_GD (PU5, pin 1 or PR70). |
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# Replace PR6 with a 56.2K resistor |
# Replace PR6 ("top" side) with a 56.2K resistor |
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# Add a 0.1 uF capacitor from |
# Add a 0.1 uF capacitor from PR6 (thick trace) to ground (one side of PR7) |
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=Results= |
=Results= |
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Revision as of 03:25, 17 July 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, which prevents power up. Boards having this problem will occasionally fail to turn on, indicated by the EC flashing the red battery charge LED.
These power issues are not exacerbated by suspend/resume testing.
This only applies to XO-1.5 A-phase (both A1 and A2) motherboards.
Problem Description
Procedure
- Cut trace between PU5, pin 3 and +1.8VSUS near C355 (keeping PC54 connected to pin 3).
- Run wire from PU5, pin 3 to 3VPCU (anode of D19, next to Q22)
- Cut trace at top of PR70, and tie to 3VPCU (at PU5, pin 3 or PC54).
- Lift Q22, pin 1 emitter, removing it from the VR_ON net. Tie Q22, pin 1 to +1.2VSUS_GD (PU5, pin 1 or PR70).
- Replace PR6 ("top" side) with a 56.2K resistor
- Add a 0.1 uF capacitor from PR6 (thick trace) to ground (one side of PR7)