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LMK04821: How to estimate parameter of External Loop filter

Part Number: LMK04821


Dear Technical Support Team,

I'd like to estimate External Loop Filter(CPOUT)  through webench.

PLL1 is bypassed and just use PLL2 through OSCin as clock generator.

Then how do I estimate External Loop Filter?

Is it possible for Webench to use only estimating Loop filter of PLL2?

If it can't, could you show another way?

■My configuration

Input(OSCin):  100MHz

Output:  30MHz

PLL1: Disable

PLL2: Enable

Best Regards,

■My Webench Project

https://webench.ti.com/wb5/OpenPublicSharedProject.jsp?id=D92026072DDEF6C8&s=c

Webench doesn't have disable check box for each PLL

ttd

  • Hi ttd,

    I don't think webench allows simulation on PLL2 only. However, I think it is fine if we do a dual pll simulation because the PLL1 sim will not affect PLL2 sim much.
    I modified the webench a little bit. webench.ti.com/.../webench5.cgi
    In PLL2, we can set VCO = 3000MHz, VCO1 divider = 5, N Prescaler = 3 and fpd = 200MHz. This will make >200kHz loop bandwidth possible.