• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 266 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS54540: TPS54540 and TPS84529

Ray Vincent Aranzaso
Genius 15175 points
Part Number: TPS54540
Other Parts Discussed in Thread: TPS84259, TPS54040A, TPS54060A, TPS5430, TPS5450

Hi,

Good Day. I have a customer who is working with TPS54540 and TPS84529. Please see below his query for your reference. Thank you very much.

I am looking for an equivalent product to TPS54540 4.5-V to 42-V Input, 5 A, Step Down DC-DC Converter but for négative output voltage. The TPS84259 4.5-V to 40-V Input, 15-W, looks the same but his case is different.

I am fine since I found these 2 products. These two products have characteristics that perfectly match my needs but I would like to have to use the same case for these 2 products: Does it possible?

I just went to know if is possible to have two identical cases for these 2 products. The output voltage for positive output will be 5 V for the second one - 5V and the current for each output will be 2 A.

I speak out the TPS54540 4.5-V to 42-V Input, 5 A, Step Down DC-DC Converter but for négative output voltage and the TPS84259 4.5-V to 40-V Input, 15-W.

Best Regards,

Ray Vincent

  • 0
    TI__Expert 3766 points

    Hi Ray Vincent,

    I believe with some additional components and careful checks on voltage stress we can use the same TPS54540 to generate a negative output with an Inverting buck boost (IBB) topology. See the following technical article by my coworker Frank below. The first questions I'd have would be on the max VIN, since the buck converter in an IBB topology will experience a greater voltage at the VIN pin composed of max VIN + negative VOUT.

    https://www.ti.com/lit/pdf/snva856

    Regards,

    Henry

  • 0 in reply to Henry Kou
    TI__Genius 15175 points

    Hi Henry,

    Good Day. Please see below the response of our customer to your reply. Thank you very much.

    I clearly noted that “ we can use the same TPS54540 to generate a negative output with an Inverting buck-boost (IBB) topology".
    The problem is that in this negative ourput voltage configuration it cannot deliver 3A only 0,9 A for a 5V output voltage:

     
    Do you confirm this data ? 
    I remind you that I need a current of 3A for a 5V output voltage.

    I just noticed that this note SLVA 317 B concerns the TPS54060A and note the TPS54040A, then I hope to have a higher output current.

    I just noticed that this note concerns.

    I found an interesting example with the TPS5430.

    There is no reason that the component  TPS54540 doesn’t work in this inverting mode: Does it true?

    The last point: I want to understand why the D parameter comes in. Finally what current will be available at a 5V output voltage (taking into account the case of the optimal input voltage)? 

     

    Best Regards,

    Ray Vincent

  • 0 in reply to Ray Vincent Aranzaso
    TI__Expert 3766 points

    Hi Ray Vincent,

    Is the output current 2A or 3A for each rail?

    I've calculated the max IOUT for you for the TPS5450 with your max and min VIN cases that maintains your output current of 3A. These were using equations 4, and 5 in the app note you found: https://www.ti.com/lit/an/slva317b/slva317b

    For max VIN of 37V, IOUT_max is 4.86A, which satisfies 3A.

    For min VIN of 6V, IOUT_max is 3A, which satisfies as well.

    Therefore, it seems that as long as your min and max VIN remains between 6V and 37V, you should be able to maintain 3A IOUT for your TPS54540 in IBB configuration.

    Regards,

    Henry