PWM comparator

AN1518

14/30

Where K is equal to 0.076. Therefore the PWM gain is also equal to:

Equation 14

This means that even if the input voltage changes, the error amplifier does not change its

value to keep the loop in regulation, thus ensuring a better line regulation and line transient

response.

In summary, the Open Loop Gain can be expressed as:

Equation 15

Example:

The gain and phase bode diagrams are plotted respectively in Figure 11 and Figure 12.

Figure 11.

Module plot

G

()

1

K

----

const

==

Gs

()

G

()

R

2

R

1

R

2

+

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

•

A

()

•

A

LC

•

s

()

=