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LMK00804B-Q1: Power Supply Filter

FRANK1
Expert 7835 points
Part Number: LMK00804B-Q1
Other Parts Discussed in Thread: LMK00804B

Hi Team,

As the TI website maintance today, I can not get more information from Web.

A customer have the inquiry below, can you clarify it?

The data sheet for the part LMK00804BQWRGTTQ1 is missing information on power supply filtering in section 10.1.1.

A filter circuit is provided in Figure 15 of section 10.1.1 but no value for the ferrite bead is given.

In addition, no information on the frequency range that needs to be attenuated is given too.

I can't design a proper power supply filter without additional information.

Can you supply the frequency range that needs to be attenuated for the device and/or the value for the ferrite bead in the recommended filter circuit of section 10.1.1?

  • 0
    TI__Mastermind 28980 points

    Hi FRANK1,

    Recommended ferrite value should aim for at least 100Ω impedance at the buffer frequency of interest. For example, if the LMK00804B is buffering a 100MHz signal, an adequate ferrite bead would ramp to at least 100Ω at 100MHz, with a comparable or higher impedance range up to at least a decade higher frequency to reject higher order harmonics.

    In general, a ferrite bead is not as helpful for omitting noise below ~30MHz, and the larger local decoupling capacitors are usually sufficient in this range.

    Regards,

  • 0 in reply to Derek Payne
    TI__Expert 7835 points

    Hi Derek ,

    Thanks a lot.

    very helpful.