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TDC7201: Can the TDC7201 be configured to measure the frequency of a 1MHz clock?

Part Number: TDC7201

I have an application where I want to continuously measure the frequency of a 1MHz clock and record small changes in the frequency.  The clock operates on a 1.8V rail.  It would seem that the TDC7201 could measure that at min VDD.  Would it be possible to monitor this continuously for up to a minute at a time?

  • Hello Jonathan,

    Thanks for considering to use Texas Instruments. Continuously monitoring individual periods of a 1MHz clock signal without missing any clock pulses for a minute is likely not possible with a single TDC7201.  Yet periodic monitoring is definitely possible.

    You can either use the device’s internal clock or use an external clock reference to set the internal clock.  Ideally you would want the TDC7201 to use a frequency a few orders of magnitude higher than 1MHz, which is feasible as it can accept a reference as high as 16MHz.  Either clock source the TDC7201 will likely have its own contribution of uncertainty from jitter.  After setting an appropriate clock frequency, you could detect up to 5 rising edges on a given stop pin.  Due to the speed of the communication protocol speed you will not be able to read data and write a subsequent start command without missing a clock pulse or two during the data transfer, regardless of whether you read back only from one register or all registers.  Another issue you will need to address is how you will provide the start pulse.  You could toggle is arbitrarily, but you might miss the first pulse if it is a few picoseconds later.  You could also have it trigger with your clock, but you may want to add some circuitry to prevent the start pin from seeing another pulse before you have read back the data.