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[ DRV425 ] Current Sensing for BLDC Motor Current

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: DRV425

[ DRV425 ] Current Sensing for BLDC Motor Current

Hi,

My customer has been looking for alternative solutions of isolated current sensor from Allegro for their BLDC motor current sensing.

ACS723: High Accuracy, Galvanically Isolated Current Sensor IC
www.allegromicro.com/.../ACS723.aspx

As far as I check the solution from TI, DRV425 could be one of suggestion for my customer.
However, it's sill not clear for my that the advantage/disadvantage over ACS723.

On top of that, I don't think my customer can use "drilled busbar" which is described in the datasheet, because they use standard PCB and wire harness between board and motor.

Can you help me to understand your solution more precisely?
Thank you for your help in advance.

Regards,
Ken

  • 0
    TI__Mastermind 32260 points

    Hello Ken,

    The DRV425 is a magnetic sensor with the range of 2mT.  This can be used to measure currents.  The benefits of this device is the Gain error is 0.04% and linearity is 0.1% along with that its drift is 7ppm/°C.  The device works from 3.0 to 5.5V.  The device measures magnetic fields so external magnetic fields that do not come from the measurement of interest must be taken into account.  The bus bar solution does a good job of eliminating some of the external fields but orientations matters.  The DRV425 has accuracy benefits but system design needs to account for distance, orientation, external fields that can impact the measurement.  The system design will also determine the isolation as the magnetic sensor will not be in contact with the current source.  With some more details I can help with a solution.

    Regards,

    Javier Contreras

  • 0 in reply to Javier Contreras4
    Mastermind 9165 points

    Hi Javier,

    Thank you for your comment. It's helpful for me!

    As my understanding, DRV425 which sense external magnetic field with internal sensor, that means it could be impacted by "external" field. So precise system design will be required.

    On the other hand, on Allegro's solution , the target current go through the inside of package, this means less sensitive from external field, may be.

    Thanks,
    Ken