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Original question:

WEBENCH® Tools/LM25117-Q1: To high Duty Cycle allowed in WEBENCH

WEBENCH® Tools/LM25141-Q1: To high Duty Cycle allowed in WEBENCH

Kim Sivebaek1
Prodigy 40 points
Part Number: LM25141-Q1

Tool/software: WEBENCH® Design Tools

Does the LM25141-Q1 suffer the same error (as LM25117-Q1) or does it just have a much higher 'Max duty cycle'? Not quite as clear in datasheet (as with LM25117-Q1).

WEBENCH setup:

LM25141QRGERQ1
Switching Frequency: 348kHz
Input: 5.3V to 38V
Output: 5.05V@4.5A
Duty Cycle: 97.66% at Vin = 5.3V

The efficiency of 97.5% seems to good to be true? (at V_in = 12V, I_out = 1.5A) Can you somehow verify?

  • 0
    Genius 4910 points

    Hi Kim,

    For the above condition the design is hitting minimum off time due to which it is failing.Please note that minimum toff for the device is 100ns as per the datasheet.

    Minimum toff = (1-Dmax)/fsw.

    Thanks and Regards,

    Atul.