Are DC switching regulators (buck regulators) suitable for fast response, high current applications?

Discussion in 'The Projects Forum' started by jellytot, Jun 10, 2016.

  1. jellytot

    Thread Starter Member

    May 20, 2014
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    I'm thinking of switching my voltage regulator in my project from a linear regulator to a switching regulator. But I don't know if a switching regulator would work in my situation. I have a solenoid (draws 2 amps), that at intervals, fires and releases very quickly (approx 15 milliseconds on then off). I have a diode and reverse zener diode to make sure the solenoid releases quickly. The timing is very important; the solenoid needs to energize very quickly, and shortly afterwards release quickly.

    Now as I understand it, the way a switching regulator works is that it "pulses" power to reduce the voltage. But does it give a stable current? Could it be used in the situation I have above? Would it help if I put a big capacitor between the regulator output and the solenoid?

    Also, I have transistor controlled relays in the project that also must react quickly (like the solenoid). Could a switching regulator affect these as well?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Regulated power supply switching periods are typically only a few microseconds, whereas the response times of relays and solenoids is much slower (e.g. milliseconds), so no problem. A switching regulator already has an output filtering capacitor.
     
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  3. crutschow

    Expert

    Mar 14, 2008
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    A standard switching regulator is efficient but has a much slower response to current transients as compared to a linear regulator (mS vs μS), due to the feedback loop response of the switcher that is limited to compensate for the LC output resonance.
    This means you may need a large capacitor at the output to handle the surge current from the solenoid.

    One exception to this is a hysteretic switching regulator which does require a slow compensation loop for stability, so can react very rapidly to current changes (feedback goes directly to the PWM comparator input).
    There disadvantage is that they tend to have more ripple in the output voltage, but that's not a problem in your application, since solenoids and relays are immune to relatively high values of ripple.
     
    Last edited: Jun 10, 2016
  4. jellytot

    Thread Starter Member

    May 20, 2014
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    Thank you.

    Thank you. Ah, OK I'll put a large capacitor between the solenoid and the output. Regarding the hysterectic regulator, in the project I have an MCU (which I had reset issues in the past) and sensors in the project. Can I expect issues? If so, then I'll go with a standard switching regulator with a large capacitor.
     
  5. crutschow

    Expert

    Mar 14, 2008
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    What type of sensors?
    What is their output voltage range and what resolution do you need?
     
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