L7986 datasheet(24/43 Pages) STMICROELECTRONICS

Part #	L7986

Description	3 A step-down switching regulator

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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Application information

L7986

24/43

DocID022450 Rev 6

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: 2

ESR COUT > 1 / BW), this zero

helps stabilize the loop. Electrolytic capacitors show non-negligible ESR (> 30 m

), 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

fZ1

 R

4 C4



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

fP0 0

fP1

 R

C4 C5



C4 C5

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



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



L7986 Datasheet(PDF) 24 Page - STMicroelectronics