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DRV110: High speed solenoid operation

azimmer
Prodigy 50 points
Part Number: DRV110

I am designing a circuit to drive a small solenoid at a very high frequency: ideally >100Hz. The solenoid I am evaluating is a Ledex 195201-234: 50% duty, 8.8V/13.1Ohm= 672mA. I only need to drive it a small fraction of the possible stroke (about 0.5mm, that's roughly 20% of possible stroke). There is a return spring.

Is the DRV110 the right driver for this application? I like the idea of being able to use different voltages, and the solenoid manufacturer recommended a constant current drive to get high speeds. I need a sawtooth waveform of stroke/time, so should I just set the keep time to zero? The solenoid manufacturer also suggests a coil suppression circuit (below).

Obviously for PWM I will need a fast recovery diode. Does the rest of the coil suppression circuit make sense, used with the DRV110? They recommended a ceramic 0.1uF cap. Thanks!

  • 0
    TI__Intellectual 1965 points

    Hi azimmer,

    The DRV110 is ideal for driving a solenoid to fully open and close. If you are trying to vary the position of the actuator in a controlled way, then the DRV110 may not be the right part for the job. The DRV110 regulates the current through a solenoid at two levels: a high level to ensure opening of the solenoid, and a low level to keep the solenoid open while reducing power. Each of these levels is controllable with an external resistor, thus it may not be possible to get a sawtooth waveform of stroke over time.

    As for the coil suppression circuit, the capacitor will lead to instability in the feedback loop for current regulation; I would not recommend using a capacitor in this context with the DRV110. I would also recommend the Zener diode voltage to be less than the supply voltage, again for stability reasons. The Zener diode is not necessary for using the DRV110, but if it improves performance in your application, then go ahead and use it.

    Let me know if you have any further questions.

    Best,

    Grant

  • 0 in reply to Grant Falkenburg
    Prodigy 50 points
    Hi Grant,

    Thanks for your response! Is there another driver you would recommend, or just a MOSFET?

    All best,
    Alex
  • 0 in reply to azimmer
    TI__Intellectual 1965 points

    Hi Alex,

    I do not know of another driver that offers on-the-fly programmable current regulation.

    One potential workaround is to use a digital potentiometer in parallel with the R_SENSE resistor, and connect the center terminal to the SENSE pin on the DRV110. This would allow the current to be readily programmable using I2C or SPI. In this configuration, I would recommend adding a 100pF capacitor at the SENSE pin to suppress any glitches that the digital potentiometer may have. Here is a schematic showing this:

    Here is a page with TI's digital potentiometers. Any of them should work in this application.

    www.ti.com/.../products.html

    Hopefully this is a viable solution for you. Feel free to ask any questions you have about this configuration.

    Best,

    Grant