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DRV8251: Current Regulation bandwidth?

Jim
Prodigy 10 points
Part Number: DRV8251

Howdy,

I'd like to replace an analog closed-loop motor current driver with DRV8251 or similar.  Particularly interested in the internal current regulation, but require bandwidths in the 10s of kHz. Unfortunately, a couple of the scope traces in the datasheet seem to indicate pretty long settling times that would exclude this part (10s of ms).

Is there a simplified method to estimate current regulation bandwidth given some motor parameters, or is simulation the only way to go?  Alternatively, are there more suitable parts to explore (desire 3.5A+, 40V+ drive, full h bridge, internal current regulation, PWM drive).

Thanks!

  • 0
    TI__Mastermind 37683 points

    Hi Jim,

    The DRV8251A will be a better option. It comes with internal current regulation using a current mirror circuit. 

    Jim said:
    Particularly interested in the internal current regulation, but require bandwidths in the 10s of kHz. Unfortunately, a couple of the scope traces in the datasheet seem to indicate pretty long settling times that would exclude this part (10s of ms).

    Where did you find this information? What are you referring to by bandwidth here. Amplifier bandwidth?

     Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    Prodigy 10 points

    Hi Pablo,

    I'm interested in the current regulation bandwidth (response of current output to changes of the PWM input).

    The ~10's of ms estimate is coming from figures 9-7 and 9-13 of the Application Curves sections in the DRV8251A datasheet here: https://www.ti.com/lit/pdf/SLVSFU6

    If I'm incorrect and faster setpoint responses are possible (for inductive loads), I'd be very interested.

    Thanks!

  • 0 in reply to Jim
    TI__Mastermind 37683 points

    Hi Jim,

    Thank you for the clarification.

    I think what you are looking for is what we call propagation delay. The propagation delay for this driver is 0.7µs - 1µs.

    Regards,

    Pablo Armet