IR3088A

2

2

)

*

*

*

2

(

1

*

)

2

(

C

C

O

PWMRMP

FB

E

E

C

CP

R

C

f

V

V

R

C

L

f

R

π

π

+

∗

∗

∗

∗

∗

=

(27)

CP

E

E

CP

R

C

L

C

∗

∗

=

10

(28)

ceramic capacitor between 10pF and 220pF is usually enough.

Type III Compensation for AVP Applications

Determine the compensation at no load, the worst case condition. Assume the time constant of the resistor and

capacitor across the output inductors matches that of the inductor, the crossover frequency and phase margin of the

LE

FB

CS

E

DRP

C

R

R

G

C

R

f

∗

∗

=

*

*

2

1

π

(29)

π

θ

180

)

5

.

0

tan(

90

1

∗

−

=

A

C

(30)

Choose the desired crossover frequency fc around fc1 estimated by Equation (29) or choose fc between 1/10 and

1/5 of the switching frequency per phase, and select the components to ensure the slope of close loop gain is -20dB

FB

FB

R

R

2

1

to

FB

FB

R

R

3

2

(31)

1

4

1

FB

C

FB

R

f

C

∗

∗

=

π

(32)

DRP

FB

FB

FB

DRP

R

C

R

R

C

∗

+

=

)

(

1

(33)

O

PWMRMP

FB

E

E

C

CP

V

V

R

C

L

f

R

∗

∗

∗

∗

∗

=

2

)

2

(

π

(34)

CP

E

E

CP

R

C

L

C

∗

∗

=

10

(35)

ceramic capacitor between 10pF and 220pF is usually enough.

Type III Compensation for Non-AVP Applications

the crossover frequency fc between 1/10 and 1/5 of the switching frequency per phase and select the desired phase

margin θc. Calculate K factor from Equation (36), and determine the component values based on Equations (37) to

(41),

)]

5

.

1

180

(

4

tan[

+

∗

=

C

K

θ

π

(36)

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