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DRV8832 mcu interface

Doane Arnold
Intellectual 335 points
Other Parts Discussed in Thread: DRV8832, DRV8832EVM

I'm designing an MCU interface between a PIC18F67J11 (3.3v) and a DRV8832. My motor is a 6V DC brushed motor. I want to use the iSense capability to limit current to 400 or 500mA. I do not need variable speed control. The system requires forward/reverse and braking. Do I need to plan for cycling the power to the DRV8832 in the event of an OCP fault or does the iSense limit prevent them from happening?

I have ordered the DRV8832EVM, but I don't understand the use of Vset and Vref. I would like to run the motor with logic levels applied to IN1 and IN2 only. Is this possible?

Doane

  • 0
    TI__Mastermind 20985 points

    Hi Doane,

    Setting IN1 and IN2 both low clears a fault, as Page 7 on the datasheet states.  The intended way to use VSET and VREF is to connect a resistor divider from VREF to GND and connect VSET in the middle.  The resistor ratio controls the VSET voltage, which controls the voltage/current regulation.  You can see Page 8 for more info on this.

    Best regards,
    RE

  • 0
    Intellectual 335 points

    I forgot to add that the DRV8832 would be powered by a 5VDC source and that Vset and Vref would be connected.

  • 0 in reply to Doane Arnold
    Intellectual 335 points

    On page 9, the datasheet states:

    Overcurrent Protection (OCP)

    An analog current limit circuit on each FET limits the current through the FET by removing the gate drive. If this

    analog current limit persists for longer than the OCP time, all FETs in the H-bridge will be disabled, and the

    FAULTn signal will be driven low. The device will remain disabled until VCC is removed and re-applied.

    Can this occur if I limit current using the iSense feature? Otherwise, it looks like I would need to cycle power to clear the fault.

    Thanks,

    Doane

  • 0 in reply to Doane Arnold
    TI__Mastermind 20985 points

    Yes, good point that clearing OCP requires cycling device power.

    ISENSE should normally be effective at limiting current without tripping OCP.  If a high current persists though, or if OUT1 or OUT2 is shorted to GND, then OCP would trip.

    Best regards,
    RE