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DRV5053 quiescent output spec

Peter Verheij
Prodigy 140 points

The only spec to be found about the Vq Quiescent output voltage is here downbelow.

This could mean literaly anything.

It could mean the devices are thermally stable but differ from device to device ,but it could also mean that any kind of temperature variation could cause the Vq to move between given boundaries.It could even mean that rising the temperature with 1 degree causes the output voltage to jump from 0.9 to 1.15V.

Long term stability data also lacks.

Can I get more specific data ?

  • 0
    TI__Mastermind 21320 points

    Hi Peter,

    I've notified the expert for this device. They should reply shortly.

  • 0
    TI__Mastermind 20985 points
    Peter, you make a valid point, but check out Figure 5, which shows how voltage and temperature affect VQ.

    Best regards,
    RE
  • 0 in reply to RE
    Prodigy 140 points

    Mhm, yes indeed. This shows roughly a ±1.5%  variation over the whole temperature span.

    Yet the Vq spec allows for a ±12% variation.

    Does this mean that if we measure the Vq in a test system,store this value in EEPROM of our MCU and compensate for it, we will only have to deal with the ±1.5% variation that can be taken from the graph in figure 5 ?

  • 0 in reply to Peter Verheij
    TI__Mastermind 20985 points
    Great question. Most of the spec range is to accommodate process variation, so you can do a 1-time measurement and store that in EEPROM. It won't shift over the device lifetime. However, the one thing to be aware of is that if you subject the device to a very strong magnetic field (0.5T), you can cause small residual magnetism on the device leadframe, which is on the order of ±20mV for the DRV5053RA -45mV/mT device.

    Best regards,
    RE
  • 0 in reply to RE
    Prodigy 150 points

    Hi Peter,

    I am trying to use a DRV5053VA to design an overcurrent protection. I would like it to activate at about 10A, which causes about 0.1V shift from the quiescent voltage. I have only digital inputs availiable on my processor, so I use two comparators to detect the low and high current limits (0.92 and 1.12V - I made a loop in the bottom layer of the pcb, which is sort of U shaped to maximise the flux through the device). If this design goes into production and we get a device with quiescent voltage of 0.9V or 1.15V, the overcurrent trip will be constantly activated. Any advice?

    Reards,

    Nandor

  • 0 in reply to Nandor Bodo
    TI__Mastermind 20985 points

    Nandor, maybe you could add a high-pass filter so that a sudden change of 0.1V is required to trip the comparator.  And during power-up, maybe the firmware could ignore the comparator for the first few milliseconds if needed.

    Best regards,
    RE

  • 0 in reply to RE
    Prodigy 150 points

    Yes, thats worth considering.

    But how many of the devices will have a quiescent voltage different from 1.02V? And by how much? What does the min and max value refer to in the datasheet? Is there a digital Hall sensor that triggers on below 1mT? Or perhaps another low cost solution to trigger on currents of about 10A and still being isolated?

    Regards,

    Nandor

  • 0 in reply to Nandor Bodo
    TI__Mastermind 20985 points
    Hi Nandor, have you considered using a shunt resistor matched with an INA series amplifier? These are widely used for sensing current <10A.

    The VQ distribution is quite Gaussian with a standard deviation of 0.02V. Per the datasheet, the spec range applies to the full temperature and Vcc range.

    Best regards,
    RE
  • 0 in reply to RE
    Prodigy 70 points
    Hi,

    how would the offset voltage of the DRV5053VA (-90 mV/mT) be affected by a strong magnetic field?
    And would this small residual magnetism you mentioned be permanent or could the device even be damaged by it?
    I am using the DRV5053VA in an array where it is important, that the offset voltages of the sensors don't change much.

    Best regards
  • 0 in reply to Robert Mencke
    TI__Mastermind 20985 points
    Robert, to clarify, -90 mV/mT is the Sensitivity, not offset (VQ). Like I mentioned, if you apply a very strong field (e.g. 500mT), that can cause residual magnetism and a change of VQ. There's no "damage" to the device.

    Best regards,
    RE
  • 0 in reply to RE
    Prodigy 70 points

    So there shouldn't be a change of VQ with a field that is slightly stronger than the measurement range of +/-9mT of the DRV5053VA?

    Thanks and best regards,

    Robert

  • 0 in reply to Robert Mencke
    TI__Mastermind 20985 points

    Yes, Robert, that is true.

    Best regards,
    RE