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OVP for an Altera MAX10 FPGA power supply (3.3V)

Tim Davis
Prodigy 225 points

Does TI recommend an Over Voltage Protection Network 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__Guru** 105361 points
    Hi Tim,

    Thanks for reaching out!
    Do you want to protect 3.3V bus against over voltages? what could be load on 3.3V bus?

    Thanks
    Rakesh
  • 0
    TI__Guru**** 150760 points
    Here is a reference design for the MAX10 that we just released: www.ti.com/.../TIDA-01366

    But it seems that you want to operate the MAX10 in its lower performance, single supply mode?

    For your OVP protection, I agree with Rakesh: we need to understand where the 3.3V on your board comes (another DC/DC, wall wart, etc.) from and why it might have an OV event.
  • 0 in reply to Chris Glaser
    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 supply rail 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__Guru** 105361 points
    Hi Tim,

    Thanks for the detailed information. We have TPS25940A device which provides overvoltage protection and cuts-off the power path in 2us (typ). It has several other functions such as voltage monitor, overcurrent and short circuit protection, fault indictor etc.
    Please go through the datasheet and I will be happy to clarify if you have any questions

    Thanks
    Rakesh
  • 0 in reply to Rakesh
    Prodigy 225 points

    Thanks for the reply.  I have quickly reviewed the datasheet.  Several questions.

    1.  Is 2usec response time fast enough during an overvoltage fault with a very supply sensitive FPGA involved?  I reviewed Fig 36 and section 9.3.2  TVS and other protection type diodes respond very quickly.

    The Ilim feature would be useful.  It appears to have a minimum setting of 0.6A.

    2.  Are there other parts available that would have a lower setting?

    Thanks,

    Tim

  • 0 in reply to Tim Davis
    TI__Guru** 105361 points
    Hi Tim,

    Currently we do not have device which can support lower current limit with OVP at 3.3V level.
    Yes, for lower voltage rail having less voltage margin to handle, 2us may not be fast enough.

    Thanks,
    Rakesh