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DRV5056: Consideration of magnet temperature drift

na na78
Guru 16770 points
Part Number: DRV5056
Other Parts Discussed in Thread: DRV5032

Hi

I want to confirm if my understanding is correct.
Could you please answer the following questions?

1.
Regarding to DRV5056 of which linear output, compensation by S_TC can be offered and Vout after compensated can be calculated with equation (1) from datasheet.
So we don't have to consider the magnet temperature drift.

Is it correct?

2.
Generally, should we have a temperature sensor as an accompanying deivce to get Ta?

3.
A switch type like DRV5032 does not offer consideration about temperature drift in datasheet.
If DRV5032 is used, it is not required to care about magnet temperature drift, isn't it?

BestRegards

  • 0
    TI__Expert 5705 points

    Hello,

    Thank you for your interest in the DRV5056.

    1) Temp coefficients for magnets are relatively constant over a wide temperature range. NdFeB magnets (which are most common) have a value of about -0.12%/'C and the DRV5056 sensitivity is compensated for it with an opposite slope, i.e. STC = 0.12%/'C.

    2) Equation 1 is a worst-case calculation and assumes a magnetic source that does not drift over temperature. In most cases where the device is used with a permanent magnet the equation reduces to VOUT = VQ + B x S owing to the built-in temperature compensation of sensitivity.

    3) The temperature drift characteristics of BOP and BRP are shown in the section 7 of the datasheet, so it is possible to estimate the new thresholds at high or low operating temperatures if necessary. Also, if the operating temperature constantly changes by large values in your application then it may be a good idea to consider using a temp sensor for re-calibrating the thresholds.

    I hope this helps.

    Best Regards,

    Harsha

  • 0 in reply to Harsha Munikoti
    Guru 16770 points

    Hi Harsha

    Thank you for your reply.

    I understood DRV5056 can adjust output analog voltage automatically depending on ambient temperature and the magnetic temperature drift can be defeated.  Is my understanding correct?

    One more question.

    The figure of magnetic threshold vs temperature from DRV5032 shows to getting decreased threshold point as temperature increases.

    Does it mean the sensitivity of DRV5032 is increased with increasing temperature?

    Is the result of temperature compensation inside device?

    BestRegards

  • 0 in reply to na na78
    TI__Expert 5705 points
    Hello again,

    Yes, your understanding of the part's behavior is correct.

    A decrease in threshold values means that less field is required to change the output state, which translates to higher sensitivity. So you are correct. Also, if you estimate the slope, you will notice that the drift in BOP (and BRP) is about 0.12%/'C (relative to nominal value in mT), which counteracts the magnet drift.

    Best Regards,
    Harsha