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LM5177: LM5177DCPR ‑ 18V-60V to 25.00V @ 4A

JOSE LOPEZ BERNAL
Prodigy 10 points
Part Number: LM5177

Tool/software:

By using WEBENCH and for requirements (18V-60V to 25.00V @ 4A)  I get the next message:

"With the design conditions, either the IC or the selected FET junction temperature is exceeded above the maximum rating.
Hence, this design is created using an ideal FET. Please note that the resulting FET parameters are ideal,
so the efficiency/loss opvals have been disabled. Also, the schematic/PCB export and Thermal simulations will not work with the ideal FET."

1. Could it be any issue with WEBENCH and LM5177? It seems to me strange

2. Must I change LM5177 for an other one?

3. By using the excel calculator it appears very different values for the INductor (2uH againts 15uH).

   - Which tool must I trust in? Excel or WEBENCH?

thank you very much

  • 0
    TI__Guru 58631 points

    Hi Jose,

    Webench is more strict and tries to gives you out of the box solution.

    While the Excel tool gives you much more freedom where you can

    - judge the cooling capabilities,

    - use MOSFETs in parallel

    - define load profiles and decide which is more important.

    The LM5177 (but recommend to use the newer device LM51770 = pin compatible) can be use for that but you need to ensure that you can handle the thermal requirements of the external circuit.

    Best regards,

     Stefan