Datasheet

Application information L7986
24/45 DocID022450 Rev 7
6.4.2 Type II compensation network
If the equivalent series resistance (ESR) of the output capacitor introduces a zero with
a frequency lower than the desired bandwidth (that is: 2π ∗ ESR ∗ C
OUT
> 1 / BW), this zero
helps stabilize the loop. Electrolytic capacitors show non-negligible ESR (> 30 m
Ω ), so with
this kind of output capacitor the type II network combined with the zero of the ESR allows to
stabilize the loop.
In Figure 13 the type II network is shown.
Figure 13. Type II compensation network
The singularities of the network are:
Equation 28
f
Z1
1
2π R
4
C
4
⋅⋅
------------------------------= f
P0
0= f
P1
1
2π R
4
C
4
C
5
⋅
C
4
C
5
+
--------------------⋅⋅
--------------------------------------------=,,