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TPS745-Q1: rise time

Shinji Tsuji
Genius 14269 points
Part Number: TPS745-Q1


Hi team,

Could you please advise the minimum rise time value (0V to 3.3V) at start up? 

I would like to know the rise time excluding start up delay (EN to start rinsing delay) to check it has >150us requirement in system.

Start up time is specified as min 200us, but it includes EN to start rising delay. 

regards,

  • 0
    TI__Expert 5231 points

    Hello,

    Have you looked at this graph for an idea of startup time regarding your application? 

    With the graph below, you can notice immediate startup and vout is naturally rising. I hope this helps clarify your question. I see around 300 us. 

    Thank you,

    Josh Nachassi

  • 0 in reply to Josh Nachassi
    TI__Genius 14269 points

    Hi Josh-san,

    Yes, I had checked it and also confirmed it on EVM.

    I would like to know the characterization data of the minimum rise time(0V to 3.3V) to make sure it doesn't violate my MCU requirement. 

    Since startup time is specified as 200us minimum in the datasheet, I wonder if rise time can meet minimum 150us. 

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Expert 5231 points

    Hi Shinji-san,

    I wouldn't expect the device to have a rise time that is smaller than what is listed on the data sheet and was described in the graph. The data is taken across the range of temperature so you can see the 200 us is at a bound of the temperature range

    Hope this helps, please let me know if you have further questions. 

    Thank you,

    Josh Nachassi

  • 0 in reply to Josh Nachassi
    TI__Genius 14269 points

    Hi Josh-san,

    The rise time is not specified in the datasheet. 

    Datasheet specifies Startup time = startup delay + rise time.

    It seems start up delay is 200us typical from the graph.

    So I wonder if rise time = Startup time - startup delay can meet >150us.

    Is there characterization data or design target available for rise time?

    regards,

  • 0 in reply to Shinji Tsuji
    TI__Expert 5231 points

    Hi Shinji-san,

    I understand your question. If we look at the graph and do not take into account, the delay that Vout has after the rise of EN it is about 300 us. This 300 us excludes the delay it has from EN, it is just the time Vout takes to rise. 

    I am going to look to see if there is more characterization regarding this part.

    Please let me know if you have any questions in the meantime.

    Thank you,

    Josh Nachassi