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DRV8214: What are the advanges of a more integrated BDC driver?

Jennifer Jordan
Intellectual 1076 points
Part Number: DRV8214
Other Parts Discussed in Thread: DRV8234

Hello! 

I am working on new design and want to eliminate external sensors and have a couple questions about the benefits. 

  • Would I pay more for DRV8214 or DRV8234 with integrated speed/voltage control and position control? 
  • How does this save me money or board space? I don’t want to spend money if I’m not gaining anything. 
  • +1
    TI__Mastermind 23421 points

    Hey Jennifer,

    Our new drivers with sensorless speed/voltage/position control can save you a lot of board space and mechanical space.  Typical brushed DC motor systems have some form of position feedback from the motor such as from a Hall-effect switch or latch and some magnets, or they'll have an optical or magnetic encoder on the back of the motor.  All of these solutions take up space, and have to be precisely assembled in specific positions around the motor.  This typically requires more wires to the motor area which increases assembly cost and complexity.  

    Our drivers remove the need for any sensors on the motor.  With just the two motor wires the device can get position feedback from the motor and use that to run the motor at a desired speed or voltage, or spin the number a desired number of counts.  You can basically use these drivers to replace an incremental encoder or a speed sensor.  These devices use a small ripple in the waveform of any brushed DC motor to detect the position.  The drivers have many settings to help you tune the driver to work with almost any brushed DC motor from 50mA up to 3.7A

    The image above illustrates a typical BDC motor with an encoder on the back of it, and the 6 wires going from the motor to the controller board.  The lower image shows that all you need is a DRV8214 or DRV8234 and the +/- motor wires to achieve the same thing.  

    Feel free to order a DRV8214EVM or DRV8234EVM to evaluate this in your system.

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 30 points

    In order to further reduce user side costs, the integrated ADC device of DRV8214 can output a digital current quantity to users. Users can use this digital quantity to achieve functions such as motor monitoring, motor protection, and locked rotor judgment. This is a very promising chip, which is recommended to be widely promoted and used in other motor drive chips.

  • 0 in reply to Ryunosuke Akutagawa
    TI__Mastermind 23421 points

    Thanks Ryunosuke, 

    Yes, that is correct.  The IMTR register outputs the current flowing through the motor. Thus removing the need for an ADC pin on the customer's MCU.  Do note that IMTR is only a 8-bit value (0-255) so the resolution of IMTR vs using an ADC is much less, since most ADCs are 10-bit (0-1023) or higher. Thank you for your kind comments.

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 30 points

    Although the accuracy of IMTR is limited, I would like to know what is the dynamic response time of the current represented by the IMTR register? Dynamic response time is important for user side functions such as current monitoring. Thank you.

  • 0 in reply to Ryunosuke Akutagawa
    TI__Mastermind 23421 points

    Hey Ryunosuke,

    The internal ADC is updated at 80kHz.  So I believe you will be limited by I2C speeds for response time.  

    Best,

    Jacob