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DRV8251: Running at low RPM with a BDC

Jennifer Jordan
Intellectual 1076 points
Part Number: DRV8251

Hello MD, 

Our Nextgen MX will use this pump: Boxer 5211.901.  This has a small 12V brushed DC motor (4W max.).  However, there are cases where we drive it at only 2V (to lower the flow rate). Currently, no PWM or anything fancy, just a lower DC voltage of 2V.

 

We're concerned that this is not the best means to run at low RPM (e.g. the motor may be on the verge of stalling).  Further, we may need to go even slower,  Can you and your motor team make a recommendation?  For example, might an H-bridge part like the DRV8251 offer some advantages?

  • 0
    TI__Mastermind 31825 points

    Hi, 

    Thank you for your questions. Our expert will review your questions and feedback to you in a day or two.

    regards

    Shinya Morita

  • +1 in reply to Shinya Morita
    TI__Mastermind 22240 points

    Hey Jennifer,

    The DRV8251 operating voltage only goes down to 4.5V, so you would have to test whether 5V + PWM (maybe 55% PWM) could achieve the slow speeds.  The DRV8251A  gives current sense feedback via IPROPI, you could use that to implement some anti-stall logic.   

    I suggest looking into the DRV8213 - It has a minimum voltage of 1.65V, so you could run all the way to 2V even with PWM if needed.  It has integrated stall detection and adjustable op amp gain for high-accuracy current sensing down to 10 mA.  However it's maximum voltage is only 11V, not 12V.  I recommend ordering an Evaluation Board - DRV8213EVM and testing it with your motor.  

    Regards,

    Jacob