Hi,
The calculations are based on formula used in AN-32. Please take a look at the AN-32 http://www.powerint.com/sites/default/files/product-docs/an32.pdf. In your formula I don't see output power for calculating the Lp.

rgds

I have reviewed the AN-32 and the result is the same. The AN-32
use the next formula for CCM
1000000 * Po Z * (1-ƞ) + ƞ
Lp = --------------------------------- * -----------------
Ip^2 * KP * (1-Kp/2) * fs min ƞ

If you introduce the AN-47 inputs and outputs

1000000 * 35W 0.5 * (1-0.8) + 0.8
Lp = --------------------------------------- * --------------------- =
1.16^2 * 0.5 * (1-0.5/2) * 119000 Hz 0.8

Lp = 582,87*1.125=655,72µH --> The same

Please reavise if I have introduced some input and output wrong in the formula.

Thanks.

Now you can see better the formula

Lp = ((1000000 * Po)/(Ip^2 * KP * (1-Kp/2) * fs min))*((Z * (1-ƞ) + ƞ)/ƞ)

If you introduce the AN-47 inputs and outputs

Lp = ((1000000 * 35W)/(1.16^2 * 0.5 * (1-0.5/2) * 119000 Hz))

*((0.5 *(1-0.8))/0.8))=

Lp = 582,87*1.125=655,72µH --> The same

Please reavise if I have introduced some input and output wrong in the formula.

Thanks.

Hi
Your calculations are correct. The AN-47 "Lp" value is based on Half frequency (Fsmin=59.4KHZ). Even though app note says "F" for full frequency it never got registered in calculations or may be just a typo by the author.

If you use Half frequency and add 10% to the calculated value you get 1445uH.

Good catch and thanks for pointing this out.

rgds