TVS vs clamping diodes

Discussion in 'General Electronics Chat' started by Gibson486, May 20, 2016.

  1. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    How is a TVS diode different than just using a regular diode? For stuff that I interface with a board (not going outside of the case), I normally just put a shottky diode to VCC and a diode to GND. However, I had a co worker say that this is not effective and it is better to use a TVS diode, although he could not explain why. Thoughts?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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  3. dl324

    Distinguished Member

    Mar 30, 2015
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    It depends.

    A clamp diode to VCC can only clamp to a diode drop above VCC. It can't protect from supply over voltage which a TVS could. A TVS can't help with negative transients unless you have a negative supply.
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    I think it all depends on what you are trying to protect against. If it is ESD and noise transients most ICs already have this protection. If you want to make it more robust you can add your diodes.
    If you are trying to protect say a five volt circuit from a 12 volt short you need to add a resistor in series before the diodes. This may also protect the driver.
    If your worried about power supply transients a TVS would be the choice. In the above cases don't forget decoupling caps from Vcc to ground.
    The clamp voltage specs on TVS usually are not very good so a short to 12 volts for example will probably still blow the input diodes in the IC.
     
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