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Original question:

[FAQ] How do I ask a technical question on E2E™︎ support forums?

LM61460-Q1: LM61460-Q1

Edward Chang
Intellectual 1630 points
Part Number: LM61460-Q1

Hi,

I wonder know what is the following 150MHz & 50MHz meaning?Is it represent the switching frequency or what?

With RBOOT short circuited to CBOOT, rise time is rapid. SW node harmonics will not roll off until above 150

MHz. If CBOOT and RBOOT are connected through 700 , slew time due to high side turn on is limited to no

more than 13 ns, 10 ns typical when converting 13.5 V to 5 V. This slow rise time allows energy in SW node

harmonics to roll off near 50 MHz under most conditions

Very appreciate for answering!

Best regards,

Edward Chang

  • 0
    TI__Mastermind 35210 points

    Edward, 

    LM61460-Q1 can switch as fast as 2.5MHz to avoid emissions in AM band, while ensuring sufficiently low harmonic energy in the FM band.

    LM61460-Q1 can pass CISPR-25 Class 5 with a small, differential EMI filter BOM with proper layout. No common mode choke will be needed.

  • 0 in reply to Marshall_Beck
    TI__Expert 6245 points

    Hello Edward,

    If the spectrum of the SW node waveform is plotted, there is a frequency at which power starts to roll of at 40 dB / decade rather than 20 dB / decade. I am attaching a slide from training.ti.com that shows this pattern.

     

     

    It is the frequency that the change in slope of the power density vs. frequency curves that is being referred to.

    Regards, Robert