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TIDA-060029: k value of 4/π

Part Number: TIDA-060029

Thank you for helping.

On page 12 of ``Design Guide: TIDA-060029'', it says ``Where k is equal to 4/π.'' I don't understand why it is ``4/π''.
Actually, I think that "2/π" is correct.

Also, on page 11, it says "Zx'=(Zo-Zx)/(Zo*Zx)", but "Zx'=(Zo*Zx)/(Zo-Zx)" is not correct. I think.

• Hello Kondou-san,

1. I believe Figure 2-10 is k = 2/π, but Figure 2-11 is k = 4/π due to signal's area decreases by half.

2. You are correct it should be Zx'=(Zo*Zx)/(Zo-Zx). We are currently working on the revision of the reference design. Thank you for pointing out this error to us!

Thank you,

Sima

I don't quite understand the "1. I believe Figure 2-10 is k = 2/π, but Figure 2-11 is k = 4/π due to signal's area decreases by half. " part, so could you explain in detail?

Thank you very much.

• Hello Kondou-san,

It might actually be just 1/π when looking into the full derivation by treating the resultant signal as a cosine from 0 to π/2 . I will look into this and get back to you.

Thank you,
Sima

• I'll wait.

thank you.

• Hello Kondou-san,

I apologize for the long delay. For figure 2-10 and figure 2-11, the derivations are within the attached pdf or word doc. If we took the full cycle of Figure 2-11, then the average value of the signal will be 0, therefore for average value, half cycles are taken. The figure scaling looks to be a bit off as well in the reference design from pre and post modulation.

LCR_TI.pdf

Thank you for your patience and let me know if there are further questions,

Sima

• The part that says "Where k is equal to 4/π." is wrong, but is the correct one "Where k is equal to 1/π."?

• Hello Kondou-san,

That is correct; k equal to 4/π is wrong. Figure 2-10 is k is equal to 2/π and Figure 2-11 is k = 1/π.

Thank you,

Sima