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DRV10975: Speed pin connection

Mason Noh
Expert 2490 points
Part Number: DRV10975

Hi TI,

I would like to know internal connection between speed pin and VCC.

Because speed pin is measured 7.7V when only VCC pin is connected and GND pin is removed.

Speed pin is connected 8.2k pull-down resistor from control board.

Please refer to the below test connecting the DRV10975EVM.

  • 0
    TI__Expert 6065 points
    Speed pin is connected through esd cell to V3P3, which is powered to Vreg, which is powered through Vcc.
    There is also an internal pull down resistor on the speed pin of minimum 55kOhms.
    When you measure voltage, what ground reference do you use, the gnd of the DRV10975 or the supply ground.
  • 0 in reply to Sanmesh Udhayakumar
    Expert 2490 points
    Hi Sanmesh,
    I used the supply ground. So this condition may cause damage to the control board.
  • 0 in reply to Mason Noh
    TI__Expert 6065 points
    1) Measure the speed pin with ground reference on the device ground to really see what voltage is output from speed pin. If you use the supply gnd pin, the speed pin voltage wont really tell you what voltage is output from speed pin since the grounds aren't connected.
    2) It is not recommended to have the GND disconnected while the power supply is connected. May I ask why are you doing so?
    3) You may not need an external pulldown resistor, since the device has an internal pull down