Closing the loop

ST1S14

18/46

DocID17977 Rev 2

Equation 7

6.2

Error amplifier compensation network

The ST1S14 embeds the error amplifier (see Figure 10) and a pre-defined compensation

network which is effective in stabilizing the system in most of the application conditions.

Figure 10. Transconductance embedded error amplifier

system stability but it is useful to reduce the noise at the output of the error amplifier.

The transfer function of the error amplifier and its compensation network is:

Equation 8

Equation 9

Q

P

1

π

m

C

1D

–

() 0.5

–

⋅

[]

⋅

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

=

A

()

A

V0

1s

+

R

c

C

c

⋅⋅

()

⋅

s

2

R

0

C

0

C

p

+

() R

c

C

c

sR

0

C

c

⋅

R

0

C

0

C

p

+

() R

c

C

c

⋅

+

⋅

+

() 1

+

⋅

+

⋅⋅

⋅

⋅

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

=

f

P LF

1

2

π R

0

C

c

⋅⋅

⋅

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

=