L6738A

Application details

Doc ID 18134 Rev 2

23/32

Figure 10.

Example of type III compensation.

●

Open loop converter singularities:

a)

b)

●

Compensation Network singularities frequencies:

a)

b)

c)

d)

To place the poles and zeros of the compensation network, the following suggestions may

be followed:

Gain

[dB]

Log (Freq)

0dB

open loop

EA gain

closed

loop gain

compensation

gain

open loop

converter gain

F

LC

F

ESR

F

F

P1

F

P2

20log (R

20log (V

F

0dB

F

LC

1

2

π LC

OUT

⋅

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

=

F

ESR

1

2

π C

OUT

ESR

⋅⋅

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

=

F

Z1

1

2

π R

F

C

F

⋅⋅

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

=

F

Z2

1

2

π

R

FB

R

S

+

() C

S

⋅⋅

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

=

F

P1

1

2

π R

F

C

F

C

P

⋅

C

F

C

P

+

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

⎝⎠

⎛⎞

⋅⋅

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

=

F

P2

1

2

π R

S

C

S

⋅⋅

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

=