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DRV8701: Schematic for driving with buttons not a Microcontroller

Daniel Pollard1
Prodigy 10 points
Part Number: DRV8701

I'm looking to build a motor controller that can be driven with push buttons, rather than needing a Microcontroller. I'd like to have push buttons that can be pressed to drive the Enable, Sleep and IN pins appropriately.

My question is, I need to have the Sleep pin high to turn the 8701 on, but I can't pull the logic level from the regulated supply from the 8701 unless the chip is not sleeping. So I guess that means that I need to take the VM supply and bring it down to a logic level that can be used to drive the sleep pin.

I put together a prototype circuit and used a 5v regulator to feed this 5v into the 8701 sleep pin and use this to send the IN1 high via a push button. I found that the 5v regulator was drawing too much current and cutting out. It could be that I made an error with this design, or perhaps I'm overlooking something. I feel like the need for another regulator is redundant given the 8701 can supply a nice output.

Does anyone have any advice on how I could design a standalone motor driver using the 8701.

Thanks and apologies if I've not understood some aspect of this design.

  • 0
    TI__Guru 56650 points

    Daniel,

    The datasheet "Functional Block Diagram" and "Typical Application Schematic" are good reference to start your design.

    Yes. You need to take the VM supply and bring it down to a logic level that can be used to drive the sleep pin. The nSLEEP pin and INx pin input current should be very small.

    Even the EVM used a MCU to control the DRV8701. But, it reserved several zero ohm resistors between MCU and DRV8701. You can remove the zero ohm resistor to disconnect the MCU control and add your input signal to the test points to realize to have push buttons that can be pressed to drive the Enable, Sleep and IN pins appropriately.