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Original question:

DRV5055: Spec of "Sensitivity"

DRV5055: Sensitivity linearity error

Shota Mago
Expert 8130 points
Part Number: DRV5055
Other Parts Discussed in Thread: DRV5057

Hi team,

My customer is asking about definition of "Sensitivity Linearity Error".

The datasheet states SLE: Sensitivity linearity error is ±1%(typ).

Does it mean ±1%*VCC error need to be considered?

e.g. In case of DRV5055A2 w/ VCC=3.3V, its sensitivity(typ) is 30mV/mT.

If applied magnetic flux density is 10mT, output voltage will be 1.65+0.03*10=1.95V (not considered temperature sensitivity here) ideally.

But when taking linearity error into account,  output voltage will be 1.95V±33mV=1.917V~1.983V.

Is this understanding correct?

Definition of linearity error in datasheet  sounds like gain error rather than linearity error.

Would it be possible to explain definition of SLE in more detailed?

Best regards,

Shota Mgao

  • 0
    TI__Mastermind 21240 points

    Sensitivity operates very similar to how you might consider Gain in an amplifier.  The overall sensitivity specification relates to the output change relative to any input change.

    However, for any amplifier there is also a specification for Gain linearity, which describes the maximum deviation from this expected ideal gain.  The method for measuring this on DRV5055 is noted in the datasheet.

    While sensitivity would typically be calculated using outputs using as much of the linear output range of the device, linearity errors are looking for the deviations of the output from the best fit line from the sensitivity calculation.  Typically any deviations are symmetrical in nature, and so there is a specification to describe the maximum error with positive and negative value inputs which is SSE. SLE is a specification to describe error between any two points that are either both positive or both negative, where no symmetry is expected.  This error may vary across operating conditions, such as supply voltage

  • 0 in reply to Scott Bryson
    TI__Expert 8130 points

    Hi Scott,

    Thanks for your informative reply!

    So how can we consider the SLE to calculate total error?

    DRV5055 datasheet states ±1%(typ) SLE.

    In case of DRV5055A2(30mV/mT), sensitivity might takes 27V/mT~33mV/mT when taking SLE into account.

    Is this understanding correct?

    If it's wrong, please let me know correct calculation.

    While, DRV5057 also shows SLE in its datasheet but there is no description about its definition.

    Is definition of DRV5055's SLE applicable for DRV5057 as well?

    Best regards,

    Shota Mago

    Best regards,

    Shota Mago 

  • 0 in reply to Shota Mago
    TI__Mastermind 21240 points

    The SLE typical 1% specification refers to the sensitivity and not to the Full scale output.  This linearity error is compounded on top of the overall sensitivity error.  So assuming the observed sensitivity using large scale values is 31 mV/mT.  The resulting possible range when factoring in SLE would then be from 30.69 mV/mT to 31.31 mV/mT.  This is representative of the worst case deviation from the best fit Sensitivity slope across the full linear output region.

    This concept would apply similarly to DRV5057, however, the output of this device is formatted to PWM rather than an analog voltage.

  • 0 in reply to Scott Bryson
    TI__Expert 8130 points

    Hi Scott,

    Noted.

    Thanks for your detailed explanation!

    Best regards,

    Shota Mago