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TDC7201: System clock specification

Paul Yeh
Genius 16125 points
Part Number: TDC7201

Hi Team,

My customer design TDC7201 and their clock value is limited.
From specification, The System clock of TDC7201 is 8 Mhz by default, and the maximum support is 16 MHz.
 
Now if customer only can provide the System clock is 14.286 Mhz (714.286 = 100/7 ), so question is 
(1) Does TDC7201 support 14.286 Mhz?
(2) When the FW is used under the system clock synchronization setting of 14.286 Mhz, will it affect the accuracy?
(3) Besides clock value, is there any other specification customer need to pay attention?
Thanks
  • 0
    TI__Mastermind 23045 points

    Hello Paul,

    1) I am not able to test at 14.286 MHz since I do not have a way to produce over 10MHz, I tested at various external clock frequencies 8.5MHz, 9.248MHz, 9.5MHz and produced good results even though my external source does not produce the best signal past 8MHz. But  as long as it is below the 16MHz it should be fine, keep in mind the clock is used as a reference clock to calibrate the internal clock.

    2) Figure 20 of the data sheet 7indicates that as the reference clock frequency is increased the standard deviation between measurements reduces, so higher frequencies give you a better and optimal performance. So the customer would be increasing accuracy instead of decreasing it.

    3) Yes, since the clock is being used as a reference clock to calibrate the internal one it needs to be extremely accurate in order to have the provide the best performance. Another thing that needs to be considered for the clock is low RMS jitter so something around < 1ps should work fine. You can read more about this in section 8.3 under "Clock Recommendations" which specifically talks in depth about these methods in order to increase accuracy.

    Best,

    Isaac