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DRV8870: Driving a single brushless DC motor from two DRV8870 in parallel

Chris Jones21
Prodigy 170 points
Part Number: DRV8870
Other Parts Discussed in Thread: DRV8873, DRV8256, DRV8874

We are using the DRV8870 driver in our design. We are running into the thermal limit and are looking for a lower RDS(on) option. One of our engineers mentioned that maybe we could just add an additional motor driver in parallel and cut our resistance that way. I can think of a few cases where this could cause some issues but I wanted to run it by TI just to see what they recommended. Can you tell me if you recommend using 2 DRV8870 in parallel or recommend another similar part with lower resistance.

thanks,

Chris

  • 0
    TI__Guru 56650 points

    Chris,

    The propagation delay of two DRV8870 cannot be exactly matched. So, one device's high side FET could be shorted by another device's low side FET.

    What is the maximum input voltage of you application? Would you check DRV8873/4 or DRV8256 (new device, not release yet)?

  • 0 in reply to Wang5577
    Prodigy 170 points

    Hello,

    Thank you for your response,

    Our design has a maximum input voltage of about 10 V. I will look into the DRV8874. It is quite a bit more expensive than the DRV8870 but might be the only option. I couldn't find any information on the DRV8256 on TI.com.

  • 0 in reply to Chris Jones21
    TI__Guru 56650 points

    Chris,

    DRV8874 has integrated current sensing circuit. So, customers could save the layout space and spending on the current sense power resistor. Also, it saves the current sense resistor power loss.

    DRV8256 should be available on ti.com soon. Maybe next month.