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DRV8838EVM: Back EMF

Piyusha
Prodigy 110 points
Part Number: DRV8838EVM
Other Parts Discussed in Thread: DRV8838,

Hi,

We are using DRV8838 EVM along with a sensor. We are supplying power to the EVM board via a USB port and to the sensor via the VM pin on the EVM board.

However, we are not getting the desired output. When we use 2 separate power sources for the EVM board and the sensor instead, we get a smooth output. We are wondering if it because of the back EMF.

 We would like to power on the sensor using the VM pin. We are expecting a similar waveform as below. 

Any help is appreciated. Thank you. 

  • 0
    TI__Guru 56650 points

    Piyusha,

    VM pin is a DRV8838's input pin which is connected to the DRV8838EVM's input.

    "When we use 2 separate power sources for the EVM board and the sensor instead, we get a smooth output. "

    Since VM is the EVM input, I won't see any difference between using 2 separated power sources for the EVM board and the sensor and using one source for both the EVM and the sensor. Would you check the two board ground connection to make sure both boards on same ground? 

    Regards,

    Wang Li