• State
  • Replies 4 replies
  • Subscribers 4 subscribers
  • Views 132 views
  • Users 0 members are here
Support feedback
Options
Options
Related

LM5156H-Q1: Constant Current Flyback using LM5156

Ashok Anand
Prodigy 10 points
Part Number: LM5156H-Q1
Other Parts Discussed in Thread: INA199, LM5156, PMP10081

Tool/software:

Hi, I am working on a concept to make a constant current flyback converter.

My idea:

Use INA199 to sense the current from an Rsense connected in series with the output secondary winding and connect the output of INA to the FB pin of LM5156. Rsense is calculated based on gain of INA(50V/V) and the current that i want to control.

Problem:

Somehow the converter is not working based on current feedback. The circuit is always working on OCP protection now. FB value stays at 700mV approx.

Questions:

Does this concept makes sense?

Can INA199 source current to the PWM controller?

Any valuable suggestions are highly appreciated

  • 0
    TI__Intellectual 880 points

    Hi Ashok,

    Thanks for using E2E! Please give us some time to look into this, thank you.

  • 0 in reply to Alicia Hao
    TI__Mastermind 29640 points

    Hi Ashok,

    This concept does make sense.
    There are existing reference designs using the same concept idea to create a CC loop.
    An example would be this PMP10081 design. It is a SEPIC circuit, but the concept should also apply for Flyback.
    https://www.ti.com/tool/PMP10081

    Right now I cannot explain why your simulation is not working properly.
    It seems like this is just a discrete model of LM5156. Have you taken all parameters from the datasheet, or is this build coming from one of our PSPICE simulation models available?

    Thanks and best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    Prodigy 10 points

    Hello Niklas,

    Thanks for the message. The discrete model i made from the datasheet block diagram. The model works with standard voltage feedback. i could not find a model that works well with Ltspice, so had to do the simulation with discrete model.

    I will go through the link that you mentioned and get back

    Thanks,

    Ashok

  • 0 in reply to Ashok Anand
    TI__Mastermind 29640 points

    Hi Ashok,

    Thanks for the feedback.
    We only have model files available for PSpice. It might be possible to transfer the PSpice model into LTSpice. (Unfortunately, I do not have a guide for this though)

    Please let me know if you have any questions on the reference design.

    Best regards,
    Niklas

**Attention** This is a public forum