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AN487 APPLICATION NOTE

APPLICATION EXAMPLE

Figure 17. Block diagram used in stability calculation.

Consider the block diagram of fig.17, representing the internal control loop section, with the application

values:

Fswitch = 200KHz, L = 100

µH, C =1000µF, Po=50W, Vo =5.1V,

Figure 18. Frequency behavior of the circuit of fig 17.

The system requires that DC gain is maximum to achieve good accuracy and line rejection. Beyond this

a bandwidth of some KHz is usually required for a good load transient response. The error amplifier trans-

fer function must guarantee the above constraints. A compensation network that could be used is shown

in fig.19.

Figure 19. Compensation network.

As

()

1sR

+

() 1sR

+

()

sR

C

1

G

M

--------

+







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

=