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Original question:

[FAQ] List of FAQs for TPS922055 / TPS922054 / TPS922053 / TPS922052 LED driver

TPS922055: FAULT signal start-up timing, when is it valid?

Magnus Thulesius
Prodigy 15 points
Other Parts Discussed in Thread: TPS922055

Tool/software:

What is the start-up timing for the FAULT pin?

From were in time does it have a valid state?

Could I use the FAULT function to power down the device? But then for how long do I have to mask off FAULT during start-up?

  • 0
    TI__Mastermind 23150 points

    Hi Magnus,

    Sorry, I am in all-day meeting today. I will reply to you tomorrow. Thanks for your understanding.

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    TI__Mastermind 30031 points

    Dear Magnus,

    I will take over this case and support you. Just want to clarify your question, what the start-up timing in detail you are looking for? For example, I am not sure if you are looking for a deglitch time when one of the fault behavior is triggered (the delay time between the fault behavior happen and the fault pin pulled low)? Maybe could you pls give a detailed description about how you plan to configure the fault function in your system?

    And yes, you can use the fault function to power down the device. From my understanding, you would like to use fault pin to power down the other device in your system (when fault behavior happen for TPS922055 and fault pulled low), am I correct? And when you are saying you have to mask off fault during start up, not sure if you are looking for a minimum VIN for a valid fault output?

    Thanks!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    TI__Mastermind 30031 points

    Dear Magnus,

    You can find below waveform as an example of Fault pin behavior when the status of the device is normal during start up. This waveform is tested with EVM default schematic. (You can refer to Users guide for EVM schematic.)

    Thank you!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Prodigy 15 points

    Dear Lucia,

    Thank you for the answer on start-up timing for the FAULTn pin.

    My understanding now is that the FAULTn pin is valid as long as the device is powered on.

    The FAULTn pin only goes active for a fault (which is kind of obvious) but I was afraid that the FAULTn was only valid once the device had been enabled using the PWM/EN pin, but that is not the case, or?

    This means that we can trust the state for FAULTn, being high/no faults, even if the enable pin is low, output OFF.

    Thanks!

    BRs

    Magnus