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DRV8818: DRV8818 Suitability

Genius 5355 points
Part Number: DRV8818
Other Parts Discussed in Thread: , DRV8711

Hi Support,

Application
Motor application: to drive stepper motor moving a 5kg load in a vertical or horizontal movement (vertically up and down, horizontally front and back)

Requirement
Power supply: 24V
Motor speed Requirement: 1125rpm (18.75 rev/sec)
Motor Acceleration/Deceleration requirement: Prefer 50 rev/sec and above
Microstepping operation requirement: 1/8
Load: 5kg

Stepper Motor used
Motor MPN: ML23HS8P4220
Motor MFG: MOONS

Please advise whether DRV8818 is a suitable motor driver for above application.

In addition... on DRV8818EVM:
1. Does this Eval Kit support (hardware IC level and software UI level) to drive a stepper up to my required speed (1175rpm) with 1/8 microstepping method?
2. Does this Eval Kit (and Motor Driver IC itself) capable of driving up to my required acceleration?

Thanks.

  • Hi ikon,

    1. Does this Eval Kit support (hardware IC level and software UI level) to drive a stepper up to my required speed (1175rpm) with 1/8 microstepping method?

    Yes, the EVM does support this.

    2. Does this Eval Kit (and Motor Driver IC itself) capable of driving up to my required acceleration?

    Assuming 50 rev/sec means at the end of the first second, the motor is spinning 50RPM faster, it is capable of meeting your required acceleration.

    Please note the motor torque curve at 24Vdc. If you need more torque, the DRV8711 can operate at higher voltages with external FETs.
  • Hi Rick,

    Found the Accel Rate (PPSPS) is capped at 12500 pps2 maximum.

    This EVM would not help us to test our stepper motor at our acceleration requirement ( 50rev/sec2 and above) (equivalent to 80000 pulse/sec2 in 1/8-microstepping operation). Do you have any solution to this?

    Or, fundamentally, is this IC DRV8818 capable of driving up to my required acceleration? (from hardware perspective, as I don’t seem to find any supporting info in DRV8818 datasheet).

    Thanks.

  • Hi ikon,

    The DRV8818 can operate at these frequencies, but the motor may not follow if the acceleration rate is too fast.

    If you want faster acceleration than 12500 PPSPS, the EVM can be modified to do this.

    R101 through R109 can be removed to allow any mcu or pattern generator to create the signals.
  • Hi Rick,

    #1. On using the MCU to create the signals... Do you have any SW code examples?

    #2. Which pin can be used to check the motor acceleration?

    Thanks.

  • Hi ikon,

    #1. On using the MCU to create the signals... Do you have any SW code examples?

    The code is available in the Hardware files of the DRV8818EVM tool folder. www.ti.com/.../slvc588

    #2. Which pin can be used to check the motor acceleration?

    There is no pin that can be used directly to check the motor acceleration.
    The HOMEn pin provides some indication. The HOMEn pin asserts once every 360 electrical degrees.
    The STEP pin also provides similar information, but may be more difficult to interpret.
  • Hi Rick,
    I’d also like to top up another question:
    What is the rationale behind TI setting the acceleration limit on the Software GUI of DRV8818EVM?
    Thanks.
  • Hi ikon,

    The firmware was written to handle the majority of stepper motor speeds and acceleration profiles.

    There are always exceptions.