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Step Down Converter, UC2845AQ or LM5576, 60V to 15V

Other Parts Discussed in Thread: LM5576, UC2845AQ, UC2845, UC2843

Hi Sir/Madam,

Previously I have designed step down converter circuit, 60V to 15V, with LM5576 and found out that there is another option to design with UC2845AQ. May I know what is the difference to design with UC2845AQ and LM5576?

Please recommend device that realize 15V isolated output for step down.

Thank you very much.

  • Hong,

    LM5576 is an integrated Simple Switcher buck converter - it includes the power FET and bootstrap internally, so externally you only need to provide the free-wheel diode and output L-C filter, so it's usually very easy to use.

    UC2845 is a general-purpose single-ended peak-current-mode PWM controller. It can be used to control any single-ended power stage, including buck, boost, flyback, forward etc. It would require an external power stage, since it is only the controller, it does not include any internal power FET.

    The UC2845 is limited to 50% Dmax - there are other versions in the family such as UC2843 that have 100% Dmax, as well as various options for VCC UV on/off levels.

    There are also many more modern CMOS versions with lower supply current, such as UCC28C4x, UCC281x, etc.

    Note that the UC2845AQ is an automotive-qualified version (signified by Q at the end of the part number), unless you need automotive grade for your application, it would be better to use non-Q versions.


    There are many possible TI power designs available. You can search all TI-Designs using the parametric search available here:
    www.ti.com/.../refdesignsearchresults.tsp

    You can refine the search by specifying your input voltage, output voltage and current, isolated/non-isolated, etc.


    I hope this helps answer your question.

    Thanks,
    Bernard
  • Hi Bernard,

    Thanks for your useful and detail reply. Appreciated.