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LM2574: Comments on LM2574

Mike Thornhill
Intellectual 795 points
Part Number: LM2574
Other Parts Discussed in Thread: LM2674

All,

In my application I am trying to generate a fixed 15VDC output from an input of 18-32VDC. I initially was looking over some linear regulators but it seems the power dissipation will be to large.  I am now exploring a switching based step-down converter such as the LM2574.

Vin(max) = 32V

Vout = 15V

Iout = 200 mA

The LM2574 looks to come in a fixed 15V version, only 4 external components required, has and Vin up to 40V and has an output current of 0.500A. This seems to be a perfect fit.

1.) I was just curious if someone had any thoughts if this was the best TI part to use for my application or any any other suggestions based on the above parameters.

2.) The case where my Vin = 32V and I am bucking down to 15V at the output with 200 mA I was wondering what would be the thermal implications of this. Will I need a heatsink, etc.?

Thanks for your comments!

-Mike

  • 0
    TI__Guru 65515 points

    It think that the LM2574 is OK for you application.

    We do have more "modern" devices, but this one provides for a fixed 15Vout, that will save

    you the feed-back divider.

    The LM2674 would also work.  You could use a smaller inductor with that device, but need a feed-back divider.

    The heatsink for these devices is the copper ground plane.

    The Webench design tool should help with your design.

    One word of caution is the size of the inductor and its resistance.  

    Webench will select a rather large inductor.  For this application I would use something like a 470uH and maybe 0.5Ohms or less.