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I'm designing a PCB with 8MHz crystal for DSPIC33EP512MU810-E/BG (https://www.digikey.com/product-detail/en/microchip-technology/DSPIC33EP512MU810-E-BG/DSPIC33EP512MU810-E-BG-ND/2765491)

On the datasheet, recommendations say that my traces should not exceed 12mm but this is the best I can do since my PCB board is defined and can't be changed.The crystal is side by side with the uC.

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I have a ground plane below the crystal and the GND polygon pour around the crystal is 7mil.

enter image description here.

Do you guys see any issue with this Crystal layout ?

Thanks,

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  • \$\begingroup\$ Mount the package underneath. \$\endgroup\$
    – Andy aka
    Commented Aug 15, 2020 at 14:33
  • \$\begingroup\$ Datasheet recommend not to. \$\endgroup\$
    – Amen0
    Commented Aug 15, 2020 at 14:39
  • \$\begingroup\$ What data sheet was that? \$\endgroup\$
    – Andy aka
    Commented Aug 15, 2020 at 14:42
  • \$\begingroup\$ ww1.microchip.com/downloads/en/DeviceDoc/70616g.pdf - p33 \$\endgroup\$
    – Amen0
    Commented Aug 15, 2020 at 14:43
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    \$\begingroup\$ Rotate the MCU 90 degrees? \$\endgroup\$
    – Justme
    Commented Aug 15, 2020 at 14:53

2 Answers 2

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I strongly suggest you use an XO to get an accurate reliable clock that does not have those issues.cheap.

https://www.digikey.com/products/en/crystals-oscillators-resonators/oscillators/172?k=&pkeyword=&sv=0&pv1989=0&pv2150=u8MHz&sf=1&FV=-8%7C172&quantity=&ColumnSort=0&page=1&stock=1&pageSize=300

If you use lots they also have programmable XO’s any tolerance

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Ah, it's probably okay, trace length is not that much greater than the recommendation.

Of course you're on your own even more than usual if it doesn't work under some conditions.

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