TMDXIDK5718：U23 (CDCE913) crystal unit load capacitor

kosuke AYAORI

Part Number: TMDXIDK5718
Other Parts Discussed in Thread: CDCE913,

hello

I have a question about the TMDXIDK5718 evaluation board.

18pF is mounted on the load capacitors C172 and C173 of the crystal unit of U23 (CDCE913).

Is this 18pF because the register value (Crystal load capacitor selection) of CDCE913 is changed from the default value? Please answer.

over 1 year ago

0 Robert Eschler over 1 year ago

TI__Mastermind 39300 points

I don't have the background information on the how the loading was computed for the CDCE913. Recommendation is to follow the CDCE913 datasheet for crystal loading. Note the TMDXIDK5718 EVM is tested and functional, but has not been validation over temperature/processes.

0 kosuke AYAORI over 1 year ago in reply to Robert Eschler

Prodigy 80 points

Hello

Thank you for your reply.

I want to refer to the capacitor constant in crystal matching on a custom board, so
TMDXIDK5718 I would like to know if the register value (selection of crystal load capacitor) of CDCE913 in the evaluation board has been changed from the default value.

+1 Robert Eschler over 1 year ago in reply to kosuke AYAORI

TI__Mastermind 39300 points

I don't have access to a TMDXIDK5718 EVM, but it is likely the XCSEL value is unchanged (default of 0xA). Again, I want to restate the EVM was not tested and/or optimized - thus improvements are possible in fine tuning the CDCE913 circuit.

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TMDXIDK5718：U23 (CDCE913) crystal unit load capacitor