This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8323R: Replace INA240 with DRV8323 integrated CSA

Part Number: DRV8323R
Other Parts Discussed in Thread: DRV8320, INA240, , DRV8323

Hi !

In our current design for 3 phase motor control design we are using DRV8320 with INA240 CSA and 0.001 Ohm shunt resistor (BOURNS CST0612-FC-R001E)

Due to a space constrains, We am considering to use DRV8323R internal current sense amplifiers instead of INA240, with same shunt resistor. Maximum motor current is 15A and motor supply is 16V.

For INA240 we can find error calculation in "Calculating Total Error" paragraph. There we see that how calcation is made based on CMRRGain errorNonlinearity errorInitial input offset voltage  etc etc

We can't find similar parameters and calculation for DRV8323R CSA?

How we can estimate total error for DRV8323R internal CSA based on electrical characteristics from page 15 in datasheet, please? Is there additional documentation for calculation CSA error for DRV8323R?

With regards,

Mladen Bruck

Stryker

  • Hello Mladen,

    The DRV8323R CSA is not an in-line current sense amplifier and can only be used as a low-side CSA.

    Gain error is reflected under the specification for "Amplifier gain" and the offset voltage is found under "Input offset error"

    You will note that the DRV8323R CSA does not have as tight of specs as the INA240. For example the DRV8323R has a gain error of around +/-3% while the INA240 has a gain error of around +/-0.2% maximum

    Thanks,

    Matt

  • Hello Matt,

    Thank you for answer.

    Why there is no CMRR parameter in specifications?

    Thanks,

    Mladen

  • Hello Mladen,

    The DRV8323R CSA is not intended to operate with a significant common mode voltage. You can see on the bottom of page 15 that the common mode input range is only -0.15 V to 0.15 V.

    I can ask the design team nonetheless if we have an estimate on CMRR.

    Thanks,

    Matt 

  • Hi Matt,

    Thank you for answer.  I am sorry 'm getting a bit pushy...

    I followed "2.1 Getting Started with Current Sense Amplifiers: Understanding error types", tutorial where is described output error due to offset voltage...
    For DRV8323 is that "Voff Input offset error"?  (from -4mV to 4mV)

    Thanks,

    Mladen

  • Hello Mladen,

    The design team is looking into the previous question on CMRR. I'm hoping they can get back to me before the end of the day today.

    Voff Input offset error is the input-referred error caused by the amplifier offset. So Voff is the error at the input. If you want to calculate the output error, multiply the Voff by the gain setting (GCSA).

    The video you are referring to is also describing offset voltage in terms of input-referred offset, and so it is the same as Voff Input offset error.

    Thanks,

    Matt