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Over Voltage Protection for a 3.3V Altera MAX10 FPGA

Tim Davis
Prodigy 225 points

Other Parts Discussed in Thread: TPD1E1B04

Does TI recommend an Over Voltage Protection Networks or a line of its ICs that can be used to protect a 3.3V Altera MAX10 FPGA?  A complex PCB I am currently working on went through an overvoltage fault and the only digital IC that was damaged was the Altera FPGA.

Experiences, thoughts, part numbers, all invited.

Thanks,

Tim

  • 0
    TI__Expert 3500 points

    Tim-

    We do have a variety of OVP devices that we can use to protect your FPGA, but I'll need a bit more information to help you specifically. What rail did you have an OVP failure on, and what is the voltage/current/signal characteristic of that rail?


    Thanks,

    Alec

  • 0 in reply to Alec Forbes
    Prodigy 225 points

    I hope I am answering your questions.

    We have a linear regulator powering the 3.3V digital supply and analog supply on the MAX10 (no other low voltage rails, values - which is nice).  The digital load current is in the 100mA to 300mA range based on mode of operation.

    There is a 12V power rail supply for the 3.3V regulator.

    The overvoltage came in through the 12V supply and went past the regulator into the 3.3V supply.  It was an open power cable, inductive type of kick (similar to load dump on cars - when open battery/alternator cable occurs).

    We are already heading the TVS route for the 12V supplies.  What is available for a 3.3V rail that is typically used.

    Tim

  • 0 in reply to Tim Davis
    TI__Expert 3500 points
    Tim-

    Is the 3.3V rail powered solely from your 12V supply? If so, then if you have a surge TVS diode on the 12V supply it should be enough without also protecting the 3.3V rail separately, as any power surges on the rail will be clamped before even reaching the regulator.

    One device you might consider on the 12V rail for protection is the TPD1S514-3. It's a protection IC for a 12V rail that provides 15kV ESD, 100V surge protection, as well as overvoltage protection. This would be the best way to completely protect your system from anything occurring on that rail.

    Let me know if you have any clarification on your application or follow up questions!

    Thanks,
    Alec
  • 0 in reply to Alec Forbes
    Prodigy 225 points
    Hi Alec:

    Thanks for the reply.

    Yes, this is helping answer the original question.
    We are looking for multiple locations for the protection - starting with the 12VDC as you point out. Catch it at the front door - so to speak.
    Can you also recommend a protection network for the +3.3VDC output of this supply - across the FPGA? I have been looking for one.

    Tim
  • 0 in reply to Tim Davis
    TI__Expert 3500 points
    Tim-

    I understand, never bad to have redundant solutions! Unfortunately at this time, TI doesn't actually offer any low breakdown voltage TVS surge diodes. This is something that is on our roadmap to develop in the middle of this year. Despite this, while I understand wanting redundancy, a diode on the 12V rail should be enough to protect your system.

    One thing to consider would be to include an ESD diode instead, many of which we offer to protect the 3.3 V rail. While these can't handle a power kick >1uS long, they would help to protect your system against the much shorter (~100nS) and much higher voltage pulses that can't be protected by the external TVS diode and would also destroy your FPGA. Let me know if you'd be interested in this and if so I can help recommend an appropriate device.

    Thanks,
    Alec
  • 0 in reply to Alec Forbes
    Prodigy 225 points
    Yes, I am interested in this and always take recommendations on any technical question. Please recommend an appropriate device.

    Tim
  • 0 in reply to Tim Davis
    TI__Expert 3500 points
    Tim-

    Your best bet is probably the TPD1E1B04. Since this is on a power rail, the important thing is having a low clamping voltage, and the TPD1E1B04 has one of the lowest clamping with protection up to 30kV which is extremely high. In addition, while the device isn't a dedicated surge protection TVS, it does offer 6A protection which will protect against some events. Placing this device onto your rail would be helpful redundancy towards making sure you won't have any failures on the bus line.

    Thanks,
    Alec
  • 0 in reply to Alec Forbes
    Prodigy 225 points
    Hi Alec:

    Thanks for the TI part suggestion. From a TI distributor, I have the clamping parts on order as well as the dev kit used to test their performance. I do understand it isn't a TVS diode.

    Tim