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AN628 APPLICATION NOTE

Figure 2.

3) RMS switch current

4) Average diode current

5) RMS diode current

6) Total RMS capacitor (CO) current

7) RMS twice line frequency capacitor current

8) RMS high frequency capacitor current

in the diagram (dotted line). This last plot gives an idea on the heavy increase of the inductor size operating

with large input voltage range.

Obviously, in real application the efficiency is less than 100% (

η < 1). The output voltage ripple, related to the

L

D

D94IN119

Q

CONTROLLER

LOAD

~

~

I

Qrms

P

O

V

lpk

-----------

2

16 V

lpk

⋅

3

π V

O

⋅⋅

-----------------------

–

⋅

=

I

Drms

P

O

V

lpk

-----------

16 V

lpk

⋅

3

π V

O

⋅⋅

-----------------------

⋅

=

I

C

I

O

16 V

O

⋅

3

π V

Ipk

⋅⋅

---------------------------

1

–

=

I

C2f

()rms

I

O

2

-------

=

I

Chf

()rms

I

O

16 V

O

⋅

3

π V

lpk

⋅⋅

--------------------------

1.5

–

=