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LM5146: Constant Current Control Scheme Consult

Stanley Dai
Expert 5810 points
Part Number: LM5146

Hi Team,

Do we have constant current control scheme based on LM5146 to recommend? Customer is consulting about it. Thanks.

Best,

Stanley

  • 0
    TI__Mastermind 22299 points

    Hi Stanley,

    See appnote below on implementing an CC/CV converter.

    https://www.ti.com/lit/an/snva829/snva829.pdf

    You will have to use a circuit like figure 1 with an external current sense amplifier that injects onto FB node.

    The design equations are also in the figure.

    Hope this helps,

    -Orlando

  • 0 in reply to Orlando Murray
    TI__Expert 5810 points

    Hi Orlando,

    Thanks for help. What if customer want to control the COMP pin of LM5146 to achieve CC(pull-up or pull-down during 0~5V range), what's the risks they may encounter? Do you recommend to do that?

    BTW, do you have more detailed schematic based on figure 1 of snva829 here? Customer has no experiences in it.

    Best,

    Stanley

  • +1 in reply to Stanley Dai
    TI__Mastermind 22299 points

    Hi Stanley,

    Why do they want to inject into COMP instead of FB?

    I don't recommend actively controlling COMP voltage, COMP is powered internally by the error amplifier and also has internal clamps that could be susceptible to damage.

    Also COMP dynamically responds to load transients in the CV condition, I wouldnt recommend messing with the COMP response.

    We suggest you inject into the loop at a high-impedance node like FB. 

    Hope this helps,

    -Orlando