Overvoltage protection of 1.5V line

Discussion in 'General Electronics Chat' started by alexandicity, Jun 28, 2013.

  1. alexandicity

    Thread Starter New Member

    Jun 28, 2013
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    Hi all!

    Long time lurker, first time poster :)

    I have a circuit with a 1.5V supply line. This is susceptible to short transients in the voltage which my load doesn't like. I would like to create some overvoltage protection.

    If it were a 5V or 3.3V line, I would simply whack a Zener and a resistance in there and shunt away any voltages spikes above 5.2V or 4.6V or something. But, zener diodes with a 1.6V reverse breakdown voltage don't seem to exist. The lowest I can get my hands on looks like 2.somethingV. I'm guessing the semiconductor physics prevents value much lower than that.

    First question: are there Zeners available at, say, 1.6V or less?

    Second question: is there another/better when to shunt spikes/manage overvoltage on a low-voltage line such as this? Preferably passive!

    Thanks!
    Alexandicity
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. alexandicity

    Thread Starter New Member

    Jun 28, 2013
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    Hi Bertus,

    Thanks for your answer. It's true, with voltages theis low, I could find two regular diodes and use their forward drops addred together. Or maybe even a single one with the right forward drop, like the SCS206AGC perhaps. However - are the forward voltages of diodes constant? I will need to read about these a little; I have never previously depended on a particular value for this, and they seem to usually be specified as "max Vf"...
     
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
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    A 1.5 volt supply line?

    What is the source of your supply?

    Have you considered an inductor-capacitor pi filter?

    Such diode protection will consume a (probably) significant amount of current.
    The I-V curve for a forward biased diode is highly non linear and you would need to get several milliamps through for stable operation.
     
    Last edited: Jun 28, 2013
  5. crutschow

    Expert

    Mar 14, 2008
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    What is the maximum voltage you can tolerate?
     
  6. alexandicity

    Thread Starter New Member

    Jun 28, 2013
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    Studiot: hmm, thanks for the warning about diodes forward current. I may be able to tolerate that; I will need to think about it! A PI controller - I'm not familiar with how those work for regulation - I will go look it up now!

    The supply is some special power supply module. I don't know the part number. I was hoping to prevent any over voltages above 1.6V, so it is quite a tight margin!

    Thanks for the thoughts so far!
     
  7. studiot

    AAC Fanatic!

    Nov 9, 2007
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    What's special about your power supply module, what current can it safely supply and how long can it maintain this supply?
    The module number is really irrelevant.

    You need to give current particular and careful thought since you do not have much voltage to play with.

    What is the load current?

    A ∏ filter is a passive network that presents a high series impedance to fast transients, but a low impedance to earth for them, thus shunting them past the load. It is not a regulator.
     
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