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LM5145: Reference design or AppNote for adding programable current controll for LM5145 or similar buck controller?

k.kral
Prodigy 180 points
Part Number: LM5145
Other Parts Discussed in Thread: LM5117,

Hello,

do you have some sample solution or app no that you would like to deal with adding programable current control for LM514 or any similar non isolated DC-DC controller?

  • 0
    TI__Mastermind 28640 points
    Hello,

    Please refer to a blog that discusses current control using the LM5117. I am referring you to this as its implements a simple method of current control using the LM5117. it also touches on a high level circuit that can be used to implement current control on a controller that does not have a CM pin.

    e2e.ti.com/.../how-to-design-a-simple-constant-current-constant-voltage-buck-converter

    Hope this helps?
  • 0 in reply to David Baba
    Prodigy 180 points

    Thanks you for information.

    I'm going back to the LM5145

    It is worth trying this or it will be very unstable

    Big red 1 is standard CV control loop with internal error amplifier

    Big red 2 . Measure current on low side shunt amplifi this voltahe on curr. Amplifier and this voltage compare with Vref for required max current in CC mode.  Output of this fast comparator is for example  0V or 3V. This voltage goes over diode and Rc to CV FB.

    If output current is under set current is on output CC comp 0V and all works in CV mode. if output current exceeds set max current is on output CC comp 3V which are dividers on resistor divider  Rc/Rfb2 on voltage higher than 800mV. Because on FB is overvoltage LM5145 redice votage and thereby reduce current.

    Does it have a chance to work or will it be a very unstable solution?

     

  • 0 in reply to k.kral
    TI__Mastermind 28640 points

    I am very sorry, I edited my initial response because I misunderstood the app note you were referring to.  I believe the basic implementation will work, you will need to make sure the current loop is slower than the voltage loop.

    Hope this helps?

    David.