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Sensitivity for DRV5053

Keiichi Kajino
Expert 2365 points
Other Parts Discussed in Thread: DRV5053

Folks,

The DRV5053 datasheet saids that there are +-10% of temperature sensitivity.

But as attached, later of spec sheets saids that sensitivity varies beyond +-10%.

I guess that this includes both initial and temperature, never goes to under/over -35/-10

in any PVT variation. Am I correct?

  

  • 0
    TI__Mastermind 20985 points

    You're exactly right.  Please see Figures 3 and 4 to see Sensitivity vs Vcc and Temp.  There's very little change.  The variance of S - Sensitivity comprehends PVT, but Process accounts for almost all of it.  This means that if your system can do a 1-time calibration, the device will be highly accurate and stable.

    Best regards,
    RE

  • 0 in reply to RE
    Intellectual 335 points
    RE,

    Thanks for the info. About the 1-time calibration, do you mean calibrating it every time the system starts. Or calibration after the production, i.e. once at all? We are also stuck with these +-10% and Sensitivity duality.
  • 0 in reply to Eray CANLI
    TI__Expert 5705 points

    Hi Eray,

    One-time calibration for gain and offset after Production will likely be sufficient, but it is always good to verify. Based on Figures 3 and 4, the gain of the device is pretty constant across temperature and supply voltage. And the offset voltage (VQ) shows <5mV variation over a 40V change in supply voltage (Figure 5) which is also quite small. In particular, for a 5V +/- 0.5V supply voltage the offset voltage (VQ) would vary <(+/- 0.5Vcc x 5mV/40Vcc) = +/-63uV.

    Best Regards,
    Harsha

  • 0 in reply to Harsha Munikoti
    Intellectual 335 points

    Hello,

    Thanks for your reply. I am still a bit confused about the parameters; if the gain is pretty constant, how should I interpret the sensitivity ranges (mv/mT) which are quite wide?

    Is it correct to say that, device output will be (gain * mag.field) + sensitivity range, in which gain is almost constant, and sensitivity range which is very wide ?

    Thanks!

  • 0 in reply to Eray CANLI
    TI__Mastermind 20985 points
    Eray,

    Sensitivity and gain are the same thing. The unit is mV/mT. The device output = VQ + Sensitivity*B. The Sensitivity tolerance for any given unit is very wide, but its drift with temperature is typically small.

    Best regards,
    RE
  • 0 in reply to RE
    Intellectual 335 points

    RE,

    Thanks for answering.

    So, DRV5053 has 6 different configurations, which are called OA, PA, RA, VA, CA and EA. These configurations have different sensitivity/gain ranges, and these ranges can overlap.

    For instance, I order a DRV5053CA, (range 10 to 35 mv/mT) and a DRV5053EA (range 20 to 70 mv/mT). These both configrations may have a same sensitivity/gain of 30 mv/mT. Is that correct?

    Thanks in advance.

  • 0 in reply to Eray CANLI
    TI__Expert 5705 points

    That is correct.

    Regards,

    Harsha

  • 0 in reply to Harsha Munikoti
    Intellectual 335 points
    Hello, thanks for clarifying.

    Now one more question arised; with the varying sensitivity/gain, does input saturation field (Bsat) changes? Or, is it limited to given value? Where is this value limited, magnetically, or electrically? Datasheet gives only Typical Value. Should we expect to change to min and max, proportionally to Sensitivity/gain ?

    Also, do you know anything about the vibration response of DRV5053 ? Should we expect the gain/sensitivity change by vibration?

    Thanks!
  • 0 in reply to Eray CANLI
    TI__Mastermind 20985 points

    The saturation point is simply when the output reaches 0.2V or 1.8V.  So it does vary with sensitivity.  Higher sensitivity will reach that point with less B-field.

    The DRV5053 characteristics won't change due to vibration, but if the distance between it and the magnet changes due to vibration then that will affect the transduced output.

    Best regards,
    RE

  • 0 in reply to RE
    Intellectual 335 points

    Thanks for the reply.

    It is clear that Voltage output is limited/saturated an 0.2 an 1.8 volts.
    The question is:
    Is the magnetic field measurement also saturated at the given level?
    Let me detail the question by an example:
    Sensor is DRV5053PA: –23 mV/mT
    The saturaton is given as 35 mT
    The sensitivity:
    • minimum -10 mV/mT
    • nominal -23  mV/mT
    • maximum -35  mV/mT
    For a magnetic field of -60 mT and a sensor with the minimum sesitivity ( -10 mV/mT)
    Case1:
    If only the output voltage is saturated:
    Output = 1000+60x10 = 1600mV or 1.6 Volt
    Case2:
    If also the magnetic field sensor is saturated at 35 mT :
    Output = 1000+35x10 = 1350 mV or 1.35 Volt
    Which calculation would be correct for this situation?
    Thanks for your answers.
  • 0 in reply to Eray CANLI
    TI__Expert 5705 points

    Eray,

    Bsat represents the input value that causes the output voltage and not the sensor to saturate. The sensor itself is linear over a much wider range of input values. 

    The linear input range is simple to calculate. Basically, the device is linear when Vout is in the range:

    0.2V < Vout < 1.8V

    As mentioned previously, Vout = VQ + B x S, where VQ and S are defined according to the datasheet. This equation can be used to solve for B as follows.

    (0.2V - VQ)/S < B < (1.8V - VQ)/S

    You can evaluate the above expression for the linear range of B for any valid combination for VQ and S.

    Regards,

    Harsha 

  • 0 in reply to Harsha Munikoti
    Intellectual 335 points
    Hello Harsha,
    This was the info I was looking for. Thanks!
    Eray CANLI