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LM3429 Desgign issue

None_feiyu
Expert 1320 points
Other Parts Discussed in Thread: LM3429

Hi All,

    Now i use LM3429 in my design.there is some spec about:

    1、Input voltage:5V；

    2、Output Voltage:18V；

    3、Output Current:3A；

    When I Use WEBENCH Design tool , it shows the current exceeds limit. My Question is :

    Q1: I don't understan the parameter about Iout/Isw,there is something wrong about the data.

    Q2: From LM3429 Datasheet ILIM=245mV/RLIM ,So if the RLIM smller the ILIM bigger,Output Current is up to 5A.

   So it seem like these current will not limit my design. Can someone tell me these why?

  • 0
    TI__Mastermind 25500 points
    Webench generally sets some sort of bounds, but that does not mean you cannot get higher than 10A switch currents. But the boundary is likely there because it could be hard depending on the switching frequency and the FET gate charge since the VCC current used to drive the FET is limited. But you can do more. Just use webench to get a design as close as you can and if you choose the FET and switching frequency correctly you can increase the maximum output current in the actual design.