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TPS74801: Possibility to test Tranzorb lightning protection on Vout

Alain Staiquly
Prodigy 10 points
Part Number: TPS74801

Hello

I use TPS74801 to power active antenna in 3V3 and a tranzorb SMLVT3V3 on output of the regulator is cabled to protect regulator from Lightning.

We need to test the value of Tranzorb in production and I would suggest to inject 1mA under 4V2 on the tranzorb to check the clamping at 4V1 according to the datasheet (TPS74801 Regulator is not powered). My questions are the following :

1/ Is the regulator able to support 4V1 on output without Input power?

2/ Are there any risk to the reliability?

3/ If not possible, can you recommend a solution? 

Best Regards

  • 0
    TI__Guru 50090 points

    Hi Alain,

    In general, as long as the absolute maximum ratings of the device are not violated, it will be fine. To answer your questions specifically:

    1/ Is the regulator able to support 4V1 on output without Input power? 

    The key here is that the output voltage should not exceed by more than 0.3V or reverse current can flow from VOUT to VIN. A common way to mitigate this is to put a Schotty diode in parallel with the regulator. 

    2/ Are there any risk to the reliability? Only if the absolute maximum ratings are violated. If VOUT is somehow pulled above the target regulation voltage, the LDO simple stops trying to regulate (i.e. the pass element is open).

    3/ If not possible, can you recommend a solution?  In question, #1 I suggested added a parallel Schottky diode to help mitigate any reverse current.

    I hope this helps.