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LM25119: Operation frequency

Zoe Ko
Expert 3280 points
Part Number: LM25119

Hi team,

The LM25119 max switching frequency is 750KHz as the datasheet mentioned.

But we would like to know if we always operate at around 918KHz.

The chip may have risk of the damage and could you provide some direction to us for what may result in the risk of the damage?  

Thank you!

  • 0
    TI__Mastermind 24075 points

    Hi Zoe, 

    The chip damage risk is very low. The main concern is some performance may not meet spec. 

    I would suggest to set Fsw at 750kHz. 

    If you have to set Fsw to 918kHz, can you explain a little bit?

    Thanks

    Qian 

  • 0 in reply to Qian Chen
    Prodigy 10 points

    Hi Qian ,

    I know the max switching frequency is 750KHz as the datasheet mentioned .

    But I use a wrong RT resistance value (24.9 ohm) , that make frequency at 918KHZ .

    Because I need to make a risk evaluation report .

    so I need to know , when I set Fsw to 918KHZ , the LM25119 circuit which part will be affected (Ex : MOSFET or CHOCK ... ) ? 

    Thanks you ! 

  • 0 in reply to user6224372
    TI__Mastermind 24075 points

    Hi Zoe, 

    What's Vin and Vout in your application?

    Below potential risk I can think of. 

    1. The switch loss is large and may cause thermal problem on MOSFET and Inductor. 

    2. The PWM off time is close to minimum off time (320ns typical, 430ns maximum). 

    Thanks

    Qian