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TPS7A26: Lightning protection for TPS7A26

Manoj Turpati
Intellectual 270 points
Part Number: TPS7A26
Other Parts Discussed in Thread: TPS73801, TL1963A-Q1

Hello TI,

I am using TPS7A26 to generate 5V outptut voltage with 2% tolerance from 8.5V input voltage and the load current required is 100mA. I would like to protect output of this LDO from Lightning strikes in the order of 125V/25A and 250V/10A without compromising the output voltage tolerance. I have a bidirectional TVS diode with 6.5V breakdown voltage but LDO output doesnt support negative voltages. I thought of using TPS255x power-distribution switch to protect the output of LDO but even it doesnt work for negative voltages. Does TI have any power distribution switch/load switch which meets my requirement ? or do you have any alternate soultion ?

Best Regards,

Manoj.

  • 0
    TI__Mastermind 37005 points

    Hi Manoj,

    Can you use one of these regulators instead?  These will allow your inputs to go negative (well beyond -6.5V) without exceeding the abs max ratings of the device.

    TPS73801
    TL1963A-Q1

    Here are some additional options from TI.com (hopefully that link works correctly; you should see 7 LDO's total). Some of these are older devices and you'll need a higher ESR output capacitor than what is offered in ceramic packages (or just place a series resistor with the ceramic capacitor to emulate the higher ESR requirement).  If you have any questions just reply back and ask, we are here to help.

    https://www.ti.com/power-management/linear-regulators-ldo/products.html#32=1&182=Adjustable%20Output%3BFixed%20Output&2192=Reverse%20voltage%20protection&451max=0.1%3B7.5&

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    Intellectual 270 points

    Hello Stephen,

    Thanks for the response ! 

    I would like to understand how the current limit function works for this device TPS73801. In datasheet it is not quite clear, its been mentioned like the it will be limited to 1.6A. Will the device goes to shutdown mode once it enters to current limit region ? what will happen when the power dissipation increases and the junction temperature reaches 125C ? will it go to thermal shutdown and Enable again once it cools down ? This ON/OFF behavior is not recommended for my application. kindly let me know these details.

    Best Regards,

    Manoj.

  • 0 in reply to Manoj Turpati
    TI__Mastermind 37005 points

    Hi Manoj,

    I think it is brick wall current limit but please give me some time to investigate and get back to you.  I hope to have something within 3 business days.

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    Intellectual 270 points

    Hello Stephen, 

    Sure, please let me know if you have some information.

    Also, I have few other questions about output voltage accuracy of  TPS73801. In TI website it says its 3%. I believe this accuracy would cover entire  temperatue range and full load current of 1.5A. But my requirement is, I need to maintain 2% tolernance for an 5V output at 100mA load current for full operating range of -40 to +125C. Would it be possible to achieve with both the TPS73801 &TL1963A-Q1 ICs ? do you have some data which can support this?

    I have a similar question regarding Load regulation as well. I believe the data given in the datasheet is for 1.5A load current ? do you know whats the load regulation at 100mA load current for 5V output ?

    Are there any parameters that i need to consider while estimating the output voltage accuracy of this LDO along with Line and Load regulation ? All i need to know whether this LDO can meet my requirement of 5V at 100mA load current for full operating range of -40C to +125C.

    Best Regards,

    Manoj.

  • 0 in reply to Manoj Turpati
    TI__Mastermind 37005 points

    Hi Manoj,

    I would expect your load regulation to improve if your load is just 100mA for these higher current devices, however we do not have any test data published in the datasheet to help guide us on what improvements we would see.  The parameters you should consider in your DC tolerance assessment are: load regulation, line regulation, reference voltage tolerance, and feedback resistor tolerance.

    Thanks,

    Stephen