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DRV8262: Can this driver drive 36V BDC from 48V supply?

John11513
Expert 5560 points
Part Number: DRV8262

Tool/software:

Hi Experts,

You know each BDC motor has a rated voltage, while motor driver device such as DRV8262 always drives motor in regulated current mode. If that means we do not need matching the supply voltage with the rated voltage of motor? For example, if the motor is rated at 36V, while supply voltage is 48V, should we step down the 48V input to 36V and then power DRV8262? Or, we can power DRV8262 from 48V input directly and set the driving current withing rated current of motor?

Thank you!

John

  • 0
    TI__Mastermind 29415 points

    Hello John,

    Thank you for posting in this forum.

    John11513 said:
    For example, if the motor is rated at 36V, while supply voltage is 48V, should we step down the 48V input to 36V and then power DRV8262?

    Generally the rate operating voltage specification of a BDC motor is meant for a direct drive from a power source with no additional current regulation. At this rated voltage the motor current would be self regulating to a steady state value at the rated velocity of the motor due to its back EMF (BEMF). There would be another specification known as insulation voltage which is usually a much higher voltage than the operating voltage specification.

    John11513 said:
    Or, we can power DRV8262 from 48V input directly and set the driving current withing rated current of motor?

    Yes, as long as you ensure the motor current does not go higher than its rated current and insulation voltage. Obviously you cannot drive the 36 V motor with a 48 V supply and DRV8262 driving at 100 % PWM duty cycle. You can set the PWM drive input duty cycle to 75 %. This will take care of the steady state velocity motor current. For the inrush startup you must use the on-chip current regulation feature and the set the VREF voltage and IPROPIx resistor to the desired value. You can also avoid current regulation and control inrush current by implementing a PWM ramp up from 0 to 75 % for a soft start of the motor. Some applications may not desire soft start, hence my suggestion for on-chip current regulation for limiting the inrush current. I hope this helps. Thanks.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    TI__Expert 5560 points

    Hi Murugavel,

    Thank you for detailed explain. I understand now. We can control the motor voltage through PWM duty cycle, and control startup inrush current through on-chip current regulation. This is PWM interface mode. What about PH/EN mode? My understanding is with PH/EN interface mode, the control input is high or low level logic input. How should control the motor voltage and current?

    Regards,

    John

  • +1 in reply to John11513
    TI__Mastermind 29415 points

    Hi John,

    PWM control can be used in both PH/EN mode and PWM mode. 

    PH/EN mode benefit is PWM input needs to be on one pin only the EN (IN1) enable pin. The PH (IN2) phase pin will control the direction of operation - see Table 6-3. Dual H-Bridge with PH/EN Interface. When the EN pin is logic high the drive is 100%, when EN pin is PWM with 50 % duty the output also would be 50 % duty and when 0 the bridge will be in high-side slow decay or brake.

    To achieve similar control with PWM mode - see Table 6-4. Dual H-Bridge with PWM Interface. In this mode both IN1 and IN2 must be logic high for high-side slow decay or brake i.e. motor in 0 % duty cycle or stopped. To drive motor in one direction IN1 = 1 and IN2 = PWM with variable duty cycle. When IN2 = 0 the output will be 100 % duty. For the opposite direction IN2 = 1 and IN1 = PWM with variable duty cycle. 

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    TI__Expert 5560 points

    Thank you Murugavel.