IR3087

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 (35), and determine the component values based on Equations (36) to

(40),

)]

5

.

1

180

(

4

tan[

+

∗

=

C

K

θ

π

(35)

K

V

V

f

C

L

R

R

O

PWMRMP

C

E

E

FB

CP

∗

∗

∗

∗

∗

∗

=

2

)

2

(

π

(36)

CP

C

CP

R

f

K

C

∗

∗

=

π

2

(37)

CP

C

CP

R

K

f

C

∗

∗

∗

=

π

2

1

1

(38)

FB

C

FB

R

f

K

C

∗

∗

=

π

2

(39)

FB

C

FB

C

K

f

R

∗

∗

∗

=

π

2

1

1

(40)

CURRENT SHARE LOOP COMPENSATION

The crossover frequency of the current share loop should be at least one decade lower than that of the voltage loop

in order to eliminate the interaction between the two loops. A capacitor from SCOMP to ground is usually enough

6

_

10

*

05

.

1

*

2

*

)]

(

*

*

*

2

1

[

*

*

*

*

*

*

65

.

0

CI

O

MI

O

O

E

CI

LE

ROOM

CS

O

I

PWMRMP

SCOMP

f

V

F

I

V

C

f

R

G

I

V

R

C

∗

∗

+

=

π

π

(41)

)

(

*

)

(

*

*

*

DAC

I

DAC

PWMRMP

I

PWMRMP

SW

PWMRMP

PWMRMP

MI

V

V

V

V

V

V

f

C

R

F

−

−

−

=

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