ir3500a International Rectifier Corp., ir3500a Datasheet - Page 34

• Manufacturer Part Number: ir3500a
• Description: Xphase3 Vr11.0 & Amd Pvid Control Ic
• Manufacturer: International Rectifier Corp.

C
A 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 voltage loop can be estimated by (28) and (29), where R
Choose the desired crossover frequency fc around fc1 estimated by (28) 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
per decade around the crossover frequency. Choose resistor R
C
R
frequency and transient load response. Determine R
C
A ceramic capacitor between 10pF and 220pF is usually enough.
Type III Compensation for Non-AVP Applications
Resistor R
the switching frequency per phase and select the desired phase margin θc. Calculate K factor from (35), and
determine the component values based on (36) to (40),
CP1
DRP
CP
CP1
and C
is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise.
is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise.
from (31) and (32).
Page 34 of 47
DRP
CP
and capacitor C
have limited effect on the crossover frequency, and are used only to fine tune the crossover
θ
C
C
C
C
R
R
R
K
f
C
CP
C
CP
CP
FB
FB
CP
DRP
1
=
1
1
=
=
=
=
tan[
=
=
=
=
2
=
2 (
2 (
10
90
4
10
V
π
1
2
π
(
I
π
π
π
4
*
R
R
*
∗
∗
∗
−
∗
C
∗
FB
∗
FB
f
R
E
R
(
A
C
f
1
f
L
1
L
180
θ
C
C
DRP
CP
+
CP
∗
+
E
∗
E
)
tan(
)
C
R
G
2
R
2
2 (
R
R
∗
∗
DRP
∗
CS
∗
FB
+
DRP
FB
π
C
C
are not needed. Choose the crossover frequency fc between 1/10 and 1/5 of
L
L
1
to
. 0
1
E
1
V
E
*
*
E
E
5 .
)
I
R
) 5
∗
∗
∗
f
)]
C
FB
C
C
C
*
∗
E
E
FB
∗
C
180
∗
R
∗
R
π
*
R
FB
R
LE
R
FB
FB
1
C
=
)
∗
∗
2
5
5
2
3
R
CP
FB
and C
LE
CP
is the equivalent resistance of inductor DCR.
from (33) and (34).
FB1
according to (30), and determine C
(26)
(27)
(28)
(29)
(30)
(31)
(32)
(33)
(34)
(35)
July 3, 2008
IR3500A
FB
and