Typical application

AN938

22/33

Doc ID 5410 Rev 10

Figure 30.

Block diagram compensation loop

Figure 31.

LC output filter

Figure 32.

Error amplifier equivalent circuit

3.7

Error amplifier and compensation blocks

The open loop gain is:

Equation 13

where Cout is the parallel between the output and the external capacitance of the error

3.8

LC filter

Equation 14

AM03512v1

A(s)

Vc/Vct

LC

α

+-

AM03513v1

Cout

Resr

AM03514v1

Ro

gm

Cc

Rc

Co

As

()

gm

R

O

1s R

c

C

c

⋅⋅

+

()

⋅

s

2

R

o

C

o

R

c

C

c

sR

o

C

c

R

o

C

o

R

c

C

c

⋅

+

⋅

+

⋅

() 1

+

⋅

+

⋅⋅⋅

⋅

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

⋅

=

A

os

()

1R

esr

C

out

s

⋅⋅

+

LC

out

s

2

R

esr

s1

+

⋅

+

⋅⋅

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

=