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DRV8876: Question about the IPROPI pin voltage of PSPICE model

Zhengquan Lu
Intellectual 1035 points
Part Number: DRV8876

Hi team,

My customer would like to use DRV8876 device in new project. They used the PSPICE model for simulation and found the IPROPI pin (RIPROPI = 2.5k) voltage no any change whatever the load current. The schematic is similar like below.

The simulation behavior seems to be different with datasheet, I don’t know the issue is PSPICE model or other. Could you please give me suggestion for this topic? Thanks a lot!

Best Regards

Zhengquan Lu

  • 0
    TI__Mastermind 37683 points

    Hi Zhengquan,

    Thank you for posting to the motor drivers forum.

    Let me research this and I will get back to you with a reply by Monday 9/21 (US time) or earlier.

  • 0 in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Zhengquan,

    What exactly is the customer not seeing similar to the datasheet? I ran a couple of simulations and everything looks okay to me. 

  • 0 in reply to Pablo Armet
    TI__Intellectual 1035 points

    Hi Pablo,

    Customer used the PSPICE model for simulation and found the IPROPI pin (RIPROPI = 2.5k) voltage no any change whatever the load current. Do you see this issue? If possible, could you please share your simulation file? Thanks a lot!

    Best Regards

    Zhengquan Lu

  • 0 in reply to Zhengquan Lu
    TI__Mastermind 37683 points

    Hi Zhengquan,

    When I ran the simulations I kept the load current constant that’s why I overlooked the IPROPI voltage. Running the simulations again exactly how like the customer’s schematic, I see the issue now. However, the IPROPI voltage is changing as the current is changing when the schematic is in the configuration shown below. I adjusted the current by changing the value of ROUT1 and ROUT2. For example, when I changed the ROUT1 to {24/0.8} and ROUT2 to {24/0.5}, the IPROPI voltage had two values depending on the direction of current. You can see that during the time when EN/IN1 and PH/IN2 (current travels from OUT1 to OUT2) are both 3.3V, V_IPROPI = 1.98V which is the expected value for the current of 0.8A (24/(24/0.8)). On the other hand, when the current direction is reversed, the current through the load will be equal to 0.5A (24/(24/0.5)) and the corresponding V_IPROPI will drop to 1.24V which is expected because of the lower current.

    My guess is that this the expected behavior of this model. What I suggest is to connect their desired load similar to what I have below but have the same load in both outputs so that the current will be identical no matter of the current direction.