Improve design with Microchip's feedback - Githubissues

yifanlu / psvsd

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Improve design with Microchip's feedback #2

Closed yifanlu closed 7 years ago

yifanlu commented 7 years ago

Microchip provided some good feedback on the design. However, in the interest of time and costs, I think the current design is "good enough" for the first run of cards. I think they will work 99.9% of the time in 99.9% of use cases. Incorporating these comments will only make it better. Lu Elec USB2244 USBCheck Review Results 6-13-2017.pdf Full Contact Via.pdf MLFApplicationNotes0908RevG[1].pdf USB 2.0 Routing Guidelines v1.0.pdf

The following will be done:

[x] Select crystal with drive level between 300uW and 500uW with 350ppm accuracy
[x] Recalculate C3 & C4, the crystal capacitors
[x] Verify C7,C8 are low ESR
[x] Improve POR circuit

yifanlu commented 7 years ago

New crystal has 6pF load capacitance. This makes C3/C4 good enough.