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LM5161-Q1: Max frequency specification

Rohit J
Intellectual 850 points
Part Number: LM5161-Q1
Other Parts Discussed in Thread: LM5161

Hello,

Can you confirm what the maximum frequency capability of LM5161 is?

Page 1 says that it is adjustable up to 1MHz.

My design Vin = 48V and Vout = 12V. According to equations 3 and 4, I should be able to get up to 1.8Mhz (boundary condition).

Can you confirm which of the above is correct?

Thanks,

Rohit Joshi

  • 0
    TI__Mastermind 40040 points
    Hello Rohit,

    Going beyond the recommendations stated in the datasheet is not advised. I suggest you keep to the 1MHz limit specified in the Datasheet.

    Hope this helps?

    David.
  • 0 in reply to David Baba
    TI__Intellectual 850 points
    Hi David,

    Thanks for your prompt response. Can you explain what the 1MHz limit is based on? The only mention is a text line on page 1.

    As mentioned before, I came up with 1.8Mhz by using Vin, Vout and minimum Ton. I wouldn't operate on a boundary condition but what issues do you see with respect to operation by using 1.5Mhz

    Thanks,
    Rohit
  • 0 in reply to Rohit J
    TI__Mastermind 40040 points
    Hello Rohit,

    The device will not have been validated above 1MHz, so you are venturing into the unknown.
    the equations will likely be inaccurate for calculating the Ton. Also, I see issues based on the ramp generation that sets the TON time. The ramp generation to duty cycle blocks have certain propagation delays associated with it which could end up limiting operation at high frequency. Also at high Duty cycles the time to reset the Ramp generation will be much shorter to implement.

    You may get it working with one part, however over temperature and part to part variation you may run into production issues?


    Hope this helps?

    David.