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DRV8873-Q1: PWM Frequency and Motor Driven Specs

Denis Christodoulopoulos
Prodigy 20 points
Part Number: DRV8873-Q1

Hello every one.

I want to simulate a coil driver circuit using a microcontroller and a motor driver. I have studied the DataSheet of DRV8873-Q1 and it is perfect. But there are some questions.

1) What is range of PWM input frequency that this IC can work properly? In the datasheet just the maximum PWM frequency has mentioned. What is the minimum PWM acceptable PWM frequency?

2) Are motor or coil specs are important? Does DRV8873-Q1 have some limitations for running loads with low/high inductances? What are the range of Resistance and Inductance of motor/coil loads that this IC can drive reliably?

I'm looking to hearing from you.

Thank you so much

  • 0
    TI__Genius 13505 points

    Hi Denis,

    I notice this is your first post - welcome :)

    For your first question, DRV8873-Q1 PWM was designed to handle a PWM frequency range from DC to 100KHz.

    As for limitations on resistance/ inductance of the load, the key limiting factor will be power dissipation in the driver itself.  Do you have some motor specs I can look at to see if there are any concerns?

    Regards,
    Mike 

  • 0 in reply to Michael Erdahl
    Prodigy 20 points

    Michael Erdahl said:

    Hi Denis,

    I notice this is your first post - welcome :)

    For your first question, DRV8873-Q1 PWM was designed to handle a PWM frequency range from DC to 100KHz.

    As for limitations on resistance/ inductance of the load, the key limiting factor will be power dissipation in the driver itself.  Do you have some motor specs I can look at to see if there are any concerns?

    Regards,
    Mike 

    Dear Mike,
    Thank you for your response.
    For my 2nd question, if the resistance of motor is Rm and the rms current through FETs and the motor is I,rms, do you mean the maximum allowable motor resistance (Rm,max) is calculated from the following relation?
    PD,max = (Rm,max+2RDS,max(on)) * I,rms,max ^ 2
    If yes, what is the maximum allowable values for I,rms and PD,max? I couldn't find them from the datasheet.
    If no, please clarify it.
    Imagine that the motor inductance and resistance are 1H and 40 ohm, respectively. Is it possible for DRV8873-Q1 to drive such a load?
    Thank you so much
    Best regards.

  • 0 in reply to Denis Christodoulopoulos
    TI__Genius 13505 points

    Hi Denis,

    The key limiting factors will be the driver's over current protection (OCP) and thermal protection mechanisms.  OCP will establish the minimum series resistance of the load, and obviously thermal protection will come into play over time.  High inductance will smooth out current peaks, and actually help with OCP.

    These app notes might be helpful:

    https://www.ti.com/lit/an/slva505/slva505.pdf

    https://www.ti.com/lit/an/slva504/slva504.pdf

    Regards,
    Mike