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DRV8837 spice model VM pin does not work

Gregory Charvat
Prodigy 20 points
Other Parts Discussed in Thread: DRV8837

Hi,

I am working with the spice model for the DRV8837, half H-bridge driver:

It seems that the motor voltage pin VM is tied to VCC inside the model.

Whatever is connected to VM has no bearing on what voltage is being fed out of the 8837.  

Whatever is connected to VM is not sinking any current into and through the 8837.  

The output voltage from OUT1 is exactly the voltage across VCC.  In addition to this, current is shown being sunk from VCC to OUT1.

Do you have an updated spice model?

Greg

  • 0
    TI__Mastermind 40295 points

    Gergory,

    Would you please upload  the circuit you are using?
    If that isn't possible, would you pleas provide a schematic?

    Regards,
    John

  • 0
    Prodigy 120 points

    Hi,

    I have extacly the same problem.

    It seems that in the netlist the VM pin is not connected to the H-Bridge part, but when you change VCC to VM at the PVDD pin of the H-Bridge, the opposite thing happens :

    No current from VCC, and all the current comes from VM.

    Moreover, there is a 60mA current offset coming from the supply that doesn't go to the output, it seems quite high for a supply current of the IC.

    Guillaume

  • 0 in reply to John Miller - Sensing
    Prodigy 20 points

    John,

    Below you will find the netlist and an output .png for my test circuit.  As you can see, the output voltage on VLOAD is identical to VCC (5V) not VM (24V).

    V1 VCC 0 5 Rser=0
    R6 0 VLOAD 50
    XU1 CTRL 0 VCC VM 0 VLOAD NC_01 DRV8837
    V3 CTRL 0 PULSE(0 3.3 0.1u 0.001n 0.001n 0.2u 1 1)
    V2 VM 0 24 Rser=0
    .tran 0 .5u 0u 0.01u
    .lib "/Users/xyz/spice and other simulations/DRV8837_PSPICE_AIO/drv8837.lib"
    .lib /Users/xyz/spice and other simulations/DRV8837_PSPICE_AIO/drv8837.lib
    .backanno
    .end

    What do you think is the problem?

    Greg

  • 0 in reply to Guillaume LEVANT
    Prodigy 20 points
    Hello,

    I wanted do some simulations with the DRV8837 and was faced with this problem too.

    Is there any solution for this yet?

    I tried to modify the netlist but without success.
    I think the current offset is generated by the high side and low side resistors RAH, RAL, RBH and RBL (see netlist), which are 100R.

    An updated Spice model would be great.

    Vincent
  • 0 in reply to Vincent Jonas
    TI__Mastermind 40295 points
    All,
    An updated DRV8837 Pspice model will appear in the device product folder tomorrow morning.
    Apologies for the long delay.
    Regards,
    John