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Original question:

DRV8881: DRV8881E and DRV8881P - Key differences

DRV8881: Setting up current limiter

Alexander Zidek
Prodigy 20 points
Part Number: DRV8881

Tool/software:

Hello everyone,

I've checked the DRV8881 documentation regarding the integrated current limiter. Is it correct that a Ref.voltage of 1.625V with 200mR sense resistor should result in a 1.23A current limit, when TRQ0/1=0 ?

Thank a lot for the support.

  • 0
    TI__Mastermind 36115 points

    Hello Alexander,

    From the datasheet formula - see below; While TRQ0/1 = 0 Torque DAC will be 100%. So ITRIP will be 1.65/ (6.6 * 0.2) for VREF 1.65V and Rsense 0.2 ohms. This calculates to 1.25A. Thanks.

    Regards, Murugavel

  • 0
    Prodigy 20 points

    Thanks a lot, at least someone could confirm this first. I've noticed that instead I have a current limit value at around 590mA. I'm also using a 32kHz PWM-signal to manage motor speeds and I also noticed that the current limit value is depending on the duty cycle. 

    Thanks a lot in advance for any ideas.

  • 0 in reply to Alexander Zidek
    TI__Mastermind 36115 points

    Hi Alexander,

    I suspect the target current was not reached during the on time due to the BEMF voltage at the target speed opposing the VM supply as well as the L and R characteristics of the motor. What is the type of motor used for driving? Could you please share the current waveform through the motor? Thanks.

    Regards, Murugavel