Datasheet
DocID022446 Rev 8 23/44
L7985 Application information
44
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: 2ESR C
OUT
> 1 / BW), this zero
helps stabilize the loop. Electrolytic capacitors show non-negligible ESR (> 30 mΩ), so with
this kind of output capacitor the type II network combined with the zero of the ESR allows
the stabilization of 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
2 R
4
C
4
------------------------------= f
P0
0= f
P1
1
2 R
4
C
4
C
5
C
4
C
5
+
--------------------
------------------------------------------- -=