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DRV8452: Measures to avoid motor out-of-step

Conor
Guru 12165 points
Part Number: DRV8452

Tool/software:

Hi,

The design condition was 160,000pps, but due to the constraints of the evaluation board, it was confirmed at 65,536pps or less. The pulses/second is assumed to be 160,000pps, but the maximum ƒSTEP is stated as 100kHz in 6.3 Recommended Operating Conditions of the DRV8452/62 data sheet.

Q1. Is 160,000pps pulses/second an operation that exceeds the recommended operation? Should it be kept within the 100kHz recommended in the data sheet?

Q2. Data sheet 6.3 states "STEP input can operate up to 500 kHz, but system bandwidth is limited by the motor load". What does this mean?

Q3. If there is anything I should check to prevent loss of synchronism, I would appreciate your advice.

Q4. From what I can see from the data sheet, it seems that when using the silent step function, loss of synchronism detection cannot be used. Is it possible to use the silent step function and loss of synchronism detection at the same time? I would like to control the motor to suppress the driving noise while avoiding step-out.

Q5. From what I can see from the data sheet, it seems that the overcurrent threshold cannot be adjusted. Can the overcurrent threshold be set by the user?

Finally, I would like to send you the motor test environment (which includes internal company information), so could you please approve my private message?

Thanks,

Conor

  • 0
    TI__Mastermind 44925 points

    Hi Conor,

    Please see below answers to your questions in the same order.

    Q1: We recommend to follow datasheet recommendations. It would be a good idea to stay within the MAX operating limit specified in the datasheet. 

    Q2: This means the STEP input and internal indexer itself can operate up to 500 kHz however the closed loop current regulation bandwidth will be limited by the stepper motor parameters L and R as well as its operating conditions which would result with far less maximum STEP rate that can be used for a specific stepper motor. 

    Q3: Usually a coil current waveform with minimum distortion would be a good indicator of the torque output of the stepper motor while running under the application's operating conditions. Stepper motors are specified with speed vs. torque plots for a specific operating voltage and full-scale current in their datasheets. If your applications operating range is outside these limits the motor may not generate enough torque to sustain operation.

    Q4: I assume you were referring to the steppe motor stall detection feature of the device which detects a stall condition of the stepper motor in an application, for example while reaching an end of travel mechanically in an application. In general, this feature will not detect occasional loss of steps in an applications. In silent step mode stall detection is not supported. Stall detection will not work in this mode of operation, cannot be use simultaneously. 

    Q5: You are correct. The overcurrent threshold is a fixed value for this product and it cannot be programmed by the user. 

    Could you please get in touch with us via TI sales contact for you in Japan? Thank you.

    Regards, Murugavel