• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 32 subscribers
  • Views 669 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TCAN4550: SPI Error during SPI Communication

TCAN4550: TCAN4550: Requirement on crystal and PCB trace

Paul Ren
Prodigy 640 points
Part Number: TCAN4550

Hi Team,

My customer is using TCAN4550. But they recently found part of the devices cannot access its registers through SPI.

They checked the crystal input and output and discovered the jitter is very high with the `bad` one.

They PCB trace connecting crystal PIN1 and PIN3 is not at the same length. One is 2.5mm longer than another.

Could you help to estimate if the trace of crystal cause such communication issue?

Is there any specific requirement on crystal of TCAN4450?

Here is customer schematic:

Here are two waveform figures of PIN1 and PIN3 on the communication issue board.

Here is waveform of crystal output with `good` communication board.

 

B.R

Paul

  • 0
    TI__Guru 70622 points

    Paul,

    Thanks for bringing this to E2E. Because the oscillator circuit is very sensitive to capacitive loading, the uneven trace lengths could be contributing to the failure by adding parasitic capacitance and inductance.

    • Is it possible to increase the load capacitors to see if this persists?
    • Does this happen at room temperature?
    • Can register 0x0008 be read on a board that is showing the jitter? The 0x000x registers should be available even if the crystal oscillator is having an issue.
    • How many boards show this vs. those that don't?
    • Can you share the part number of the crystal?

    Regards,