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TDC7201: about TDC7201 calibration and testing

Vera Mao
Expert 5065 points
Part Number: TDC7201

hi dear supporting team,

customer is  using our TDC7201, and want to get confirmation on below questions, thank you very much!

  1. They use it test cycling signal with 1start and 5 stop,  the cycle of start is 1s,  and they need continuous test the gap, and report the value every 1s, so btw each test , should they do “start new measurement setting”?   from d/s, it seems needed, while when test the EVK ,we can see the GUI can continuous reporting the result without need additional clicking the panel. 

  2. How to set the calibration2_periods to make LSB smaller？ From my understanding, the bigger the better, while from fig22,  when test higher then 200ns, the error will be bigger than 60ps,  is it result with calibrationed or not?  so it seems conflict.

3. If customer set these regs to max value, is there any consequence? 

  1. TDCx_COARSE_CNTR_OVF、TDCx_CLOCK_CNTR_OVF和TDCx_CLOCK_CNTR_STOP_MASK

  • 0
    TI__Mastermind 31655 points
    Hi Vera,

    1. The GUI is set up to continuously trigger. It does this by setting the Start New Measurement bit each time after a measurement has been completed. The customer will need to set the Start New Measurement bit each time a new measurement is needed. There are many ways this can be done, but the result registers must be read before starting a new measurement or they will be overwritten.

    2. The LSB size does not depend on the number of calibration periods, only on the environmental conditions. The calibration only accounts for the error introduced by the environmental conditions, and increasing the number of calibration periods only increases the accuracy of the calibration. The chart that you show is the inherent error when using Mode 1, and can not be calibrated out. The reason the error increases so much above 500ns is because the internal ring oscillator is only useful for shorter time measurements. For measurements greater than 500ns, please use measurement mode 2.

    3. The first two registers are the overflow registers. They can be set to the max value, and this will give the TDC7201 the maximum time to take measurements before stopping due to overflow. The TDCx_CLOCK_CNTR_STOP_MASK must be set to a value lower than the overflow registers. Any stops that occur before the STOP_MASK value is reached will be ignored. If the STOP_MASK is set to max, then no stops will ever be measured.

    Regards,