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TMAG5110: What is the relationship between propagation delay tPD and sampling interval?

Part Number: TMAG5110

Hi team, 

I found that "7.5 Electrical Characteristics" says tPD typical value is 12.5us. Could you tell me your comment for lower questions?

a) "8.3.4 Propagation Delay" says "The first graph shows the typical case. The magnetic field goes above the BOP value at the moment where the output is updated. The part will then only need one cycle of tPD to update the output.". Does it mean its actual propagation delay is tPD=12.5us?

b) "8.3.4 Propagation Delay" says "The second graph shows a magnetic field going above the BOP value just right before half of the sampling period. This is the best case possible where the output will be updated in just half of the sampling period". Does it show its actual propagation delay is 0.5*tPD=6.25us? In addition, why the best case is before "half" of the sampling period? Does it mean the least sampling time to update update is 0.5*tPD? 

b) "8.3.4 Propagation Delay" says "Finally, the third graph shows the worst possible case where the magnetic field goes above the BOP value just after half of the sampling period. At the next output update, the value will still see a value under the threshold and will need a whole new period to update the output." Does it indicate its actual propagation delay is 1.5*tPD=18.25us?

Regards,
Ochi

  • Ochi-san,

    Thank you for reaching out with your question. The total conversion time for each input sample is approximately 12.5 us. The device will integrate over this conversion time and will effectively calculate the average value of the field during that period. Assuming that the changes in any magnetic field input are mostly linear, then when the input crosses a threshold  with at least 1/2 the total integration time remaining the end result will produce an output transition.  Conversely, if the input transition occurs with less than half the integration time remaining, then the sensor will register a field just below the threshold at the end of that conversion, and the output will not change until the next sample.

    Thank you,

    Scott

  • Hi Scott, 

    I understood total conversion time is approximately 12.5us. It uses average value in this conversion time. Ii the case magnetic field is linear and cross its threshold within one conversion duration, the output is really depending on how much detected magnetic field is above/below its threshold because it affect its averaged value.

    Thank you, it is clear.

    Regards,
    Ochi