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LM5156-Q1: Step up IC solution

Daniel Wang (auto)
Intellectual 2640 points
Part Number: LM5156-Q1
Other Parts Discussed in Thread: LM5155, LM5156

Tool/software:

Hello team,

Good day.

Here is an IC selection requirement from customer:

  • Input Typical 12V (9-16)
  • Output 90V
  • Output Current, RMS 1.1A

I found LM5156-Q1, but not sure it is the most suitable one, can you recommend the best solution?

Thanks!

  • 0
    TI__Mastermind 25750 points

    Hi Daniel,

    Thanks for using the e2e forum.
    LM5155 and LM5156 are both suitable devices for this application.
    However, at minimum Vin of 9V, the required duty cycle to boost to 90V get very high (~90%). This is close the maximum duty cycle the device can handle.
    The datasheet lists the limits here:

    If customer runs the device at low switching frequency, the device should be able to support a Boost application.
    If they prefer higher safety margin or are at risk of even lower Vin, they can consider using a Flyback topology with the same IC and adjust the winding ratio to reduce the required duty cycle.

    They can go through some calculation with our quickstart calculators or the Power Stage Designer tool.
    https://www.ti.com/product/LM5156-Q1#design-tools-simulation

    Please let me know if they have additional questions on the device.
    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Intellectual 2640 points

    Hello Schwarz,

    Thanks for your reply.

    About Power Architecture. We need to support 90W (about 90V 1.1A) output after boost, so it is hard for SEPIC/Flyback. So, do you have recommended IC/Design Architecture?

    Thank you!

  • 0 in reply to Daniel Wang (auto)
    TI__Mastermind 25750 points

    Hi Daniel,

    Thanks for the clarification.
    As mentioned before, Boost design should be feasible here if they run at low switching frequency (e.g. 100 - 300kHz)

    I did check for some reference designs. One example could be this one, which boosts from 6V to 80V, but has lower power ratings. The adjustable output voltage circuit would not be required.
    https://www.ti.com/tool/PMP21629

    You can check for other suitable designs here:
    https://www.ti.com/reference-designs/

    Best regards,
    Niklas