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TPS2661: Power supply protection with TPS26612

Cameron Jones
Prodigy 10 points
Part Number: TPS2661
Other Parts Discussed in Thread: TVS3301

Hi, I have a number of questions about using TPS26612 in the circuit below as depicted in the datasheet (page 31):

  • Is a TVS3301 recommended to be placed across the loop I/O pins AND/OR or between each pin and GND? This was specified in some of the other applications circuit diagrams for the TPS2661x, but omitted in this one. I would like some clarity on that choice.

  • In this arrangement, should both EN pins be toggled to disable the loop, or is just one of them acceptable? Are there any differences with using one over the other?

  • Which SGOOD should be polled? Are either okay? Is an OR necessary?

  • In short circuit fault-case where the TPS is current-limiting, are both ICs sharing the heat dissipation or will only one of the devices be limiting? If it will be a single device, which one?

  • Does +Vs have to be from the same 24V supply given that the overvoltage condition is (+Vs) + 1.50 [V]?

  • Is the only purpose of the signal diode to prevent damage from the 24V input being wired in reverse, or is there a more intricate reason?

Thank you very much!

  • 0
    TI__Guru* 79181 points

    Hi Cameron,

    Please see my response inline:

    • Is a TVS3301 recommended to be placed across the loop I/O pins AND/OR or between each pin and GND? This was specified in some of the other applications circuit diagrams for the TPS2661x, but omitted in this one. I would like some clarity on that choice.

      TVS can be placed at the input side of eFuse between VIN and GND. 

    • In this arrangement, should both EN pins be toggled to disable the loop, or is just one of them acceptable? Are there any differences with using one over the other?

      I think disabling any one eFuse should break the loop. Disabling the upper one will disconnect supply so might help in some power saving in battery based applications.

    • Which SGOOD should be polled? Are either okay? Is an OR necessary? I will recommend doing an OR. 

    • In short circuit fault-case where the TPS is current-limiting, are both ICs sharing the heat dissipation or will only one of the devices be limiting? If it will be a single device, which one?

      Theoretically, If short is happening at ADC side then the eFuse before it should be limiting because other eFuse should not detect the high current.

    • Does +Vs have to be from the same 24V supply given that the overvoltage condition is (+Vs) + 1.50 [V]? We can use other supply from +VS different from VIN supply.

    • Is the only purpose of the signal diode to prevent damage from the 24V input being wired in reverse, or is there a more intricate reason? It is damage prevention only from 24V reverse connection.

    Thank you very much!

    Regards

    Kunal Goel

  • 0
    Prodigy 10 points

    Hi Kunal,

    Kunal Goel said:
    TVS can be placed at the input side of eFuse between VIN and GND

    What about the OUT side of the TPS26612 on the top? Does this need a TVS3301 between it and GND? Why not one across the 2 wire transmitter pins like in the other application circuits?

    Kunal Goel said:
    Theoretically, If short is happening at ADC side then the eFuse before it should be limiting because other eFuse should not detect the high current.

    What about a short across the 2-wire transmitter?

    Kunal Goel said:
    We can use other supply from +VS different from VIN supply.

    How is this possible? Wouldn't over-voltage protection trip if IN > +Vs + 1.5?

    Thanks,

    Cameron

  • 0 in reply to Kunal Goel
    Prodigy 10 points

    Hi, is it possible to get a response to my questions below?

  • 0 in reply to Cameron Jones
    TI__Guru* 79181 points

    Hi Cameron,

    Sorry for delay.

    Kunal Goel said:
    TVS can be placed at the input side of eFuse between VIN and GND

    What about the OUT side of the TPS26612 on the top? Does this need a TVS3301 between it and GND? Why not one across the 2 wire transmitter pins like in the other application circuits? Since output side is not a port where someone can apply external supply or cause miswiring so TVS across device or from OUT to GND can be skipped. 

    Kunal Goel said:
    Theoretically, If short is happening at ADC side then the eFuse before it should be limiting because other eFuse should not detect the high current.

    What about a short across the 2-wire transmitter? Here top eFuse should detect first. 

    Kunal Goel said:
    We can use other supply from +VS different from VIN supply.

    How is this possible? Wouldn't over-voltage protection trip if IN > +Vs + 1.5? Overvoltage protection is there but that does not mean we can not use separate supplies.

    Regards

    Kunal Goel