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DRV5055: Behavior of quiescent voltage

Christian Funke
Prodigy 20 points
Part Number: DRV5055

Hello,

I want to use the DRV5055, in a combination with a microcontroller, as a magnetic field zero-cross detector. That's why I'm interested in the behavior of the quiescent output voltage. The datasheet shows a range from 2.43V to 2.57V (5V supply voltage) and that's my first question: Is it possible to measure the quiescent voltage during production line and store this as an offset, or will the offset be different after every restart of the sensor? Maybe you can sketch the internal structure to get a better understanding of how the quiescent voltage will be generated or the reason for this massive offset range.

Another point is the temperature related drift of the quiescent voltage, this is specified with +/-1% of VCC, which means +/-50mV for 5V operation. Is it right to add both differences to get the maximum output error? Than the worst  case would be +/-70mV as initial error and +/-50mV as temperature related error, so overall +/-120mV?

Regards

Christian

  • 0
    TI__Mastermind 26025 points
    Hello Christian,

    Thank you for using the TI forum. I will be looking into this question, and will get back to you within a day.
  • 0
    TI__Mastermind 26025 points
    Hello Christian,

    The initial quiescent voltage (2.43V to 2.57V at 5V supply) is consistent per each device, and can therefore be calibrated out at production. The spec that affects the individual device over time is "Quiescent voltage lifetime drift" which is how much the individual device quiescent voltage can change over the whole device lifetime. This value is spec'd at <0.5%. so at a 5 V supply, this would be a maximum of ±25mV.

    As for your second question, for the worst case drift, this would be the sum of the other drifts. So, if you calibrated out the initial offset, then the temperature drift combined with the maximum lifetime drift would have a total error of up to ±75mV.

    If you are mostly concerned about the voltage range, then you could use a 3.3V supply. After calibrating the initial offset, the then the combined temperature drift (33mV) and lifetime drift (16.5mV) would be ±49.5mV.
  • 0 in reply to Mitch M
    Prodigy 20 points

    Hello,

    Thank you for your reply and for the explanation, my questions are answered.

    Regards

    Christian