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WEBENCH® Tools/LM5116: LM5116 const current Source

Jonas Frey42
Prodigy 30 points
Part Number: LM5116
Other Parts Discussed in Thread: LM5117

Tool/software: WEBENCH® Design Tools

Hello,

I was wondering if it is possible to set up a const current source with the LM5116. I already used WEB Bench tool to simulate the circuit but I am not sure how to realize n current control correctly. The Input of the buck converter is fixed to 60V. The output should supply between 4-5A const current and should stop by 56V as a maximal output voltage. I would really appreciate your advice on this topic.

 

Greetings from Germany,

Jonas Frey

Research Assistant at the Karlsruhe Institute of Technology

  • 0
    TI__Guru 73602 points
    Hi Jonas,

    You can use an output shunt and an op-amp to adjust the FB node voltage to acheive CC/CV operation.

    Regards,
    Tim
  • 0 in reply to Timothy Hegarty
    Prodigy 30 points
    Hi Tim,

    thanks for your fast response.
    Are there any reverence designs for this circuit? What problems will occur when I just use the current sense resistor described in 8.2.2.4 in the datasheet as a current limiter. Will I not be able to get a "smooth" constant current source because the LM5116 will constantly pull itself in over current protection and just shut down and restart, or might I be able to get a smooth constant current source this way. The Error Amplifier Compensation is very clearly explained in 8.2.2.15 for CV mode. Is there a similar information for an CV/CC mode compensation?

    Greeting Jonas
  • 0 in reply to Timothy Hegarty
    Prodigy 30 points
    Hi
    we still got the same problem. We measured to output current via a shunt and an op-amp. We set the feedback voltage to reache 1,215V if the current is arround 5A. and just got ride of the voltage output divider because cv is not necassary for our application. The FB gets internal pulled to ground and the current feedback is not working.
    Can someone explain why the fb pin always stay low ?
    The op-amp should be able to drive the 3.7nF C_HF. If we add a series 51 ohm resistor between the opamp output and the fb pin the fb pin stays low and the opamp output goes to 1,3V (Maximum current for the connected load)

    I appreciate any adive.

    Greetings Jonas