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Crystals not working on CC2640 custom PCB

Yoo Hsiu Yeh
Intellectual 425 points

Other Parts Discussed in Thread: CC2640, CC2590

Hi all,

I have laid out a board with the CC2640 based on the reference design 

The main difference is that I have added a CC2590 gain amplifier chip between the CC2640 and the antenna.

My problem right now is that neither of the crystals (24MHz or 32.768kHz) are responding.  I have checked the pinouts, checked that none of the DNM components were accidentally placed, and DCOUPL is at 1.27V and VDDR is at 1.67V.  This is true on all the boards I have.

I don't think the gain amplifier should affect the crystals on the CC2640.  The circuit for the CC2590 I based off the schematic.  Between the CC2640 and CC2590 I have the footprint for an 0402 inductor that is not placed on the board.

Please let me know if you have any suggestions!

  • 0
    TI__Guru** 106705 points
    Hi Yoo,

    Are the crystals within the CC2640 requirements (as stated in the datasheets)? How do you verify that the crystals are not running (remember to not probe directly on the 24 MHz crystal)? Can you post your schematic and layout? What SW are you running?

    Cheers,
    Fredrik,
  • 0 in reply to Fredrik K
    Intellectual 425 points
    Hi Fredrik,

    Thanks for your reply. I was not running any software, which was the problem! I thought the chip would by default automatically power the crystals, but apparently it doesn't: e2e.ti.com/.../1588704

    Thanks for replying, I am sure you could have told me the same answer too. Thanks!
    I have flashed the SimpleBLEPeripheral code onto the chip for testing.

    thanks,
    Yoo Hsiu