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LP8860-Q1: Open/Short LED detection

Valeri Pruman
Prodigy 80 points
Part Number: LP8860-Q1

Hello

In our application we use this driver with all 4 outputs connected together. What is not clear for me - is how the IC can detect an Open or Short LED in such configuration?

Thanks

Valeri

  • 0
    TI__Intellectual 1235 points
    Hi Valeri,

    In display mode for short fault to be detected you would need to have at least one functional string (at least one output should be within the headroom window).

    Kind Regards,

    David
  • 0 in reply to David Diaz Quintana1
    Prodigy 80 points

    Hi

    I didn't understand your answer.

    We have one string of 10 LEDs per driver (all 4 outputs are shorted together in order to achieve high current). Now, for example, if one LED is shorted, how driver determines this failure?

    Thanks

    Valeri

  • 0 in reply to Valeri Pruman
    TI__Intellectual 1235 points
    Hi Valerie,

    In other words, what I'm trying to say is that you would need at least one good string to be able to detect short faults with LP8860. Thus, the short event cannot be detected with single string applications (all the outputs connected together) because you wouldn’t have any functional string (without short) operating within the headroom window (requirement to detect short events). The purpose behind this specific fault/detection scheme for shorts was mainly intended to mitigate thermal constrains when a high number of individual strings was used. Notice that the same wouldn't apply for open detection (open fault is can be detected with single string configuration). Also, there are other devices in our portfolio that provides higher flexibility for your application (from the short fault detection view point) such as LP8863. Please contact our local sale office for more information.

    Kind Regards,

    David
  • 0 in reply to David Diaz Quintana1
    Prodigy 80 points

    Hi

    Now it is clear.

    Thank You

    Valeri