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DRV8312-69M-KIT: Current Sensing using Opamp

Shammas Mohyaddin
Prodigy 20 points
Part Number: DRV8312-69M-KIT


I am using the DRV8312-69M-KIT with F28069 microcontroller. There seems to be an issue with the current sensing opamp. According to the reference materials I should get 1.65 V for 0 Ampere current (according to the following equation) 

Opamp Output Voltage  = 1.65 V + 19.1 (Rsense * Current(in Ampere))

But i am getting around 0.9 V opamp output , when i pass 0A current. 

Is it a hardware problem?

Please suggest a suitable solution.

Thanks in advance.

  • 0
    TI__Guru** 116290 points
    Don't connect motor, and power on the EVM kit, use multimeter to meaure the voltage on Ia/Ib/Ic-FB test point. What voltage do you measure? The voltage is near 1.65V, if not, follow evm guide to check the switchs on board.
  • 0 in reply to Yanming Luo
    Prodigy 20 points

    I disconnected the motors, used an oscilloscope to measure the voltage at the Ia/Ib/Ic/Itotal-FB test point. Still getting around 900 mV output when no current flow is there.

    I then used a rheostat as a load and the test point voltage seems to follow the relation given below :

    Test Point Voltage(Ia/Ib/Ic/Itotal-FB test point) = 0.9 + 19.1(I * Rsense)

    Could you guide me further?