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DRV8313: Drive exception

Annie Liu
Genius 10295 points
Part Number: DRV8313

Hi Team,

The customer is experiencing below issue and needs your help.

When one of the PWM waves is given and enabled by the MCU, all three items are output. Measured by an oscilloscope, the three-phase enable terminal has irregular high-level signals, and the PWM input terminal also has abnormal high-level PWM waveforms. There is no problem in separately testing the PWM wave and EN signal given by the MCU, but the above abnormality occurs when put together.

Before this phenomenon occurred, the drive had a normal output. But after the above-mentioned abnormality, there was no normal output. 

Customer would like to know:

What is the main reason for the above phenomenon? MCU is powered by 3.3V, DRV8313 is powered by 25V, but there is no common ground between the two. Is it caused by this? Does the drive ground and MCU ground need to be connected together?

Thanks,

Annie

  • 0
    TI__Mastermind 26046 points

    Hi Annie,

    Thanks for posting to the MD forum!

    If the grounds planes are split for the DRV8313 and the MCU, you will be referencing different grounds and getting abnormal high-level voltages on the input and/or output signals. 

    Can you connect the grounds together and see if the problem is still occurring? 

    If it continues to occur, can you share scope shot of the above phenomenon occurring? Can you share a schematic of the DRV8313 device and connections to the MCU? 

  • 0 in reply to Aaron Barrera
    TI__Genius 10295 points

    Hi Aaron,

    Thank you very much for your support. After the two grounds are connected together, the driver returns to normal, and the output waveform and input are not affected.

    Customer also would like to know if the two grounds are connected together, will the power ground cause interference to the digital circuit, especially the analog part?

    Thanks,

    Annie

  • 0 in reply to Annie Liu
    TI__Mastermind 26046 points

    Hi Annie,

    Good to hear the driver is working normal now.

    When connecting two grounds (especially power ground and digital ground), it is good practice to connect them with a minimal yet thick enough area to minimize interference while ensuring the current path to turn on/off the FETs is sufficient. This can be through a wide 0-ohm resistor, net tie, thick wire, or pin (similar to DRV8353EVM GND connecting through the Launchpad pin connector).