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DRV8353: DRV8353 Current Output

Peter Mirtschink
Prodigy 220 points
Part Number: DRV8353
Other Parts Discussed in Thread: INA240

Dear Team,

after esolve the problem with demaged ICs I now test more and more and try to get a current output from the internal amplifier. I run with a PWM of 4 kHz and 33% duty. Power supply say 2,5 Ampere curent flow into the system. But the current amplifier from DRV8353 show at osciloscope maximum output at 3,3 Volt. Gainsetting is 10 V/V. I use the 7 mOhm Shunt at the EVAL Board.

I also tested the INA240 with 3 mOhm Shunt and get also full output 3,3 Volt at 2,5 Ampere Input!

How did I measure a real current value?

Regards,

Peter

  • 0
    TI__Guru 65240 points
    Peter,

    Please work through the example in the DRV8353 datasheet at section 9.2.1.2.4. This will help you adjust for the correct settings/resistor/resolution.

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    Prodigy 220 points

    Hi Adam,

    I hove done and calculate the approx. output voltage at 2,5 Ampere. Should be with shunt of 7mOhm and Gain 10V/V = 0,175 V Output + 1,4V middlevoltage.

    But my Output at osciloscope is 3,3 Voltage at 2,5 Ampere. I don't know what to change. Attached you can see the wave at the osciloscope, sensed at ISENA at the DRV8353 Eval board,

    Regards,

    Peter

  • 0 in reply to Peter Mirtschink
    Prodigy 220 points

    Hi Adam,

    after more test I think, that I have found the problem. I have measured with INA240 in Power Supply Line and can see approx. 2,5 ampere current. So I know that measuremend is right. Then I reduce the GAIN to 5V/V at DRV8353 and I can see that now the maximum voltage is 2,5 Volt. So aprrox 28 ampere in the motor. I think, that the motor line and low side show the real current, the power supplie current is lower because at the EVAL-Board are two big capacitors. I will continue measuremend with bigger current sensor!

    Can you confirm, that this is possible?

    Regards,

    Peter

  • 0 in reply to Peter Mirtschink
    TI__Guru 65240 points
    Peter,

    Yes this is likely, the power supply current usually does not show the correct current as compared to the phase current because of the other board components, supply caps providing the bulk current, also the phases aren't only conducting one at a time in all situations.

    Regards,

    -Adam