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TPS61165: Open LED protection

Kengo.Y
Guru 10735 points
Part Number: TPS61165

Hi team,

I'd like to know about Open LED protection.
The datasheet shows detection at 38V output(Fig 7).
I think that there is a diode on the output so, does the SW pin exceed the absolute maximum rating?

I measured the SW pin that is above 40V.
So I am concerned about the possibility of breakage.

Sincerely.
Kengo.

  • 0
    TI__Mastermind 29070 points

    Hi Kengo-san,

    To trigger LED open protection, both of the following conditions have to persist for 8 switching clock cycles: (1) the SW voltage exceeds the VOVP threshold, and (2) the FB voltage is less than half of regulation voltage. So only with SW over OVP threshold won't trigger this protection. 

    The recommended Vout is from Vin to 38V.

    BR

    Patrick

  • 0 in reply to Patrick Yao
    Guru 10735 points

    Hi Patrick-san,

    Thank you for your reply.
    Yes, I know the condition for LED Open protection.

    I believe that the SW pin will not exceed 40V.
    Why does the SW pin exceed 40V?

    Is the SW pin up to 38V as measured in the datasheet?

    Sincerely.
    Kengo.

  • 0 in reply to Kengo.Y
    TI__Mastermind 29070 points

    Hi Kengo-san,

    May I have a look at your schematic? You could send me by message if there is confidential concern.

    And how many LEDs in series of your LED string? Because the IC will try to regulate the FB pin voltage to 200mV during operation, so if there are too many LEDs in one string, the Vout and SW might over 40V.

    BR

    Patrick

  • 0 in reply to Patrick Yao
    Guru 10735 points

    Hi Patrick-san,

    Thank you for your comment.
    I'll request to get a schematic for my customer.
    If I get it, I'll send you by private message.

    And, at this time no LED, because We check open LED protection.

    Sincerely.
    Kengo.