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TPS55340: Flyback Controller Recommendation for 24V input and 30W output

Manjesh Gowda Ramegowda
Prodigy 70 points
Part Number: TPS55340
Other Parts Discussed in Thread: LM5158, LM5157, LM5156, LM5185

Tool/software:

Hi Team,

I have been looking for the Flyback controller which supports my application but could not get the suitable fit so far. 

Specifications

Vin= 22V to 26V (24V Nominal)
Vout= 18V
Pout= 30W max

Preference -> Integrated Mosfet

I have tried with different controllers in calculator tools and webench designer but did not work out. Could you please help me finalize the controller for my application? would appreciate to have couple of the controllers to know before proceeding.  I am also fine using external FET if necessary.

Thanks alot
Manjesh

  • 0
    TI__Mastermind 22810 points

    Hi Manjesh,

    I think you should start with LM5158 considering the voltage stress and peak current.

    You may start with SNVR508 — LM515x Quickstart Calculator for Flyback Regulator Design.

    Best Regards,

    Feng

  • 0 in reply to Feng Ji
    Prodigy 70 points

    Hi Feng Ji,

    Unfortunately, the LM5157 series (LM515x) doesn’t seem suitable for my application. These devices are unable to handle the required peak primary current. They only work in cases where the secondary turns are kept below 2, which is not practical in my design.

    I’ve attached a screenshot for your reference. Could you please have a look and let me know if I’ve made any mistake in my analysis? or could you suggest for any other solution for my application?

  • 0 in reply to Manjesh Gowda Ramegowda
    TI__Mastermind 22810 points

    Hi Manjesh,

    You need to reduce the turn ratio to reduce the primary peak current. Another note is to start from 100-400kHz.

    However, we have around 20% peak current margin here.

    You may consider LM5156 (with external FET) if you want to have more margin in peak current.

    Best Regards,
    Feng

  • 0 in reply to Feng Ji
    Prodigy 70 points

    Hi Feng,

    thank you for your honest answer. However, I have looked for the external FET options and I feel LM5185 also suits my application and I am thinking to finalize this controller for my Flyback. 

    For my application I would need tight output regulation (below 3%) i think it would be possible with LM5185 with PSR.

    Please let me know if you think LM5156 has edge over LM5185.

    Thank you and Regards,
    Manjesh

  • 0 in reply to Manjesh Gowda Ramegowda
    TI__Mastermind 22810 points

    Hi Manjesh,

    You are right. LM5185 is a better option compared to LM5156 here.

    Best Regards,

    Feng