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DRV8323R: Isolator in between MCU and DRV8323R for INHx and INLx

Mitesh Vishwakarma
Prodigy 30 points
Part Number: DRV8323R
Other Parts Discussed in Thread: DRV8323

Hi

I am using Isolator to DRV8323 6X PWM Input INHx and INLx pins for isolate driver part with different power domain. I observed that there is 8ns delay between input and output pins and rise/fall time same as controller output.

The motor without isolator is running perfectly , with iso there are distortion in motor commutation, cause of that FETs are taking high amount of current to rotate the motor. there is no fault flag i can read from fault registers.

What could be the reason to not following the same commutation to the output ?  

Isolator Specification  :

Output Rise/Fall Time - tR/tF 2.5 ns

Typical SWITCHING SPECIFICATIONS -

            Pulse Width PW 6.6 ns

            Data Rate 150 Mbps Max

            Propagation Delay tPHL, tPLH  8.7 ns

Sourcing Current - 4.4 mA @ 1 Mbps

  • 0
    TI__Genius 15126 points

    Hey Mitesh,

    Thank you for the question. I will consult the team and aim to provide feedback by middle of next week.

    Best Regards,

    Akshay

  • 0
    TI__Mastermind 18916 points

    Hi Mitesh, 

    Just porting in the system-level resolution here in case we need to refer back to it in the future. Answer was discussed over email 

    Confirmed resolution: increase dead-time between HS/LS driver, as isolator delay was causing high current from rise & fall mismatch. Also, tweaked the filter of sense resistor at the ground side. .

    Please help mark the thread resolved if possible. Thanks! 

    Best Regards, 
    Andrew