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DRV8701: heavy loaded Motor is stalling when the PWM is on low state

Nimantha Mandula
Prodigy 40 points
Part Number: DRV8701

I am using DRV8701E motor controller for my Controller circuit. also, I am using PIC18f87k22  microcontroller to a controller the commands and PWM (Oscillator: 64Mhz Internal , PWM frequency 30000 ). Everything is working fine but when the motor is driven with a heavy load, It is more likely to stall, specially when I set up Low PWM like 50 ( using Mikro C compiler ) the motor is stalling if it is heavily loaded but without a load, it's driven normally.  Is there anyway to fix this issue ? thanks 

  • 0
    TI__Genius 14487 points
    Hello Nimantha,

    Can you please clarify when you see the motor stall and when you see the motor operate correctly?

    Just to confirm, you are sending a 30 kHz PWM signal to the EN pin, correct? What is the state of the PH pin?
  • 0 in reply to James Lockridge19
    Prodigy 40 points

    The motor is only stalling when the pwm duty is low and the motor is heavily loaded. If PWM duty is maximum , the motor is working fine also, the motor without a load is working fine even the PWM duty is low. Only the motor is stalling when the motor got heavy load and running with low speed ( Low PWM ).

    Yes Im sending PWM signal to EN pin and PH pin is used for giving the direction to the motor , like  logic 1 for Forward and Logic 0 for Backward. 

  • 0 in reply to Nimantha Mandula
    TI__Genius 14487 points
    Nimantha,

    If you only have an issue at a large load, then it sounds like there is not enough current to drive the load. The amount of current in a motor determines the motor torque. If the current regulation of the device is regulating the current, then you can changes VREF, Av, or RSENSE to regulate at a higher current. If the current regulation is not regulating the current, then you may need a higher supply voltage.