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TPS543C20A: VIN vs VOUT conditions

JH Shin
Guru 10880 points
Part Number: TPS543C20A

Hello,

My customer is considering using the TPS543C20A with the three VIN/VOUT cases below.

    CASE 1 : VIN=12V, VOUT=5V

    CASE 2 : VIN=4.5V~5.5V, VOUT=0.85V

    CASE 3 : VIN=5.7V, VOUT=4.5V

When they did the design simulations with TI webench, CASE 3 didn't run on TI webench.

Is there any condition the user must observe between VIN and VOUT of the TPS543C20A?

Is CASE3 not supported with TPS543C20A?

Thank you.

JH

  • 0
    TI__Expert 8446 points

    Hi JH,

    What switching frequency is being used in Case 3?

    There is a minimum off time of 250ns, at some switching frequencies 5.7Vin and 4.5Vout requires an off time lower than 250ns.

    Regards,

    Britton

  • 0 in reply to Britton Jones
    Guru 10880 points

    Hi Britton,

    Thanks for your reply.

    They didn't input the switching frequency separately as shown below.

    When they click 'Open design' the reference design is not created with the message below.

    Any switching frequency available on the TPS543C20A can be used.

    Is there any way they can use CASE 3?

    Thanks,

    JH

  • 0 in reply to JH Shin
    TI__Mastermind 32350 points

    Hi JH, 

    Webench is design tool that is based on equations that try to model the devices, sometimes it has limitation on covering all the use cases. Your case is one of them. As you can see below, i try even to do 6Vin, the tool does not handle it. 

    I recommend to use the calculation tool attached 

    slurb00 (5).zip

    thanks! 

    Tahar