ir3082pbf International Rectifier Corp., ir3082pbf Datasheet - Page 24

• Manufacturer Part Number: ir3082pbf
• Description: Xphase Amd Opterontm/athlon 64tm Control Ic
• Manufacturer: International Rectifier Corp.

Type II Compensation
Determine the compensation at no load, the worst case condition. Choose the crossover frequency fc between 1/10
and 1/5 of the switching frequency per phase. Assume the time constant of the resistor and capacitor across the
output inductors matches that of the inductor, R
where L
and may be needed in some applications to reduce the jitter caused by the high frequency noise. A ceramic
capacitor between 10pF and 220pF is usually enough.
Type III Compensation
Determine the compensation at no load, the worst case condition. Choose the crossover frequency fc between 1/10
and 1/5 of the switching frequency per phase. Assume the time constant of the resistor and capacitor across the
output inductors matches that of the inductor, R
is equivalent output capacitance.
Choose resistor R
C
ceramic capacitor between 10pF and 220pF is usually enough.
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 LGND is usually enough for
most of the applications. Choose the crossover frequency of current share loop (f
frequency of voltage loop (f
Where FMI is the PWM gain in the current share loop,
CP1
is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise. A
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and R
CE
C
C
C
C
C
R
R
R
CP
FB1
CP
CP
CP
FB
FB
SCOMP
SCOMP
are the equivalent output inductance and ESR of output capacitors respectively. C
1
=
=
=
=
=
=
according to Equation (31), and determine C
2 (
10
10
2 (
4
1
2
=
=
π
π
π
R
⋅
⋅
. 0
(
⋅
1
R
V
⋅
⋅
FB
R
R
f
65
C
PWMRMP
O
+
f
L
L
f
C
C
CP
1
CP
C
), and determine the C
1
−
E
E
2 (
)
⋅
)
⋅
V
2
⋅
⋅
R
π
2
R
C
C
⋅
PWMRMP
PWMRMP
⋅
FB
L
⋅
E
E
L
⋅
E
1
f
V
to
C
E
C
⋅
o
PWMRMP
⋅
C
⋅
C
C
E
−
⋅
E
E
V
⋅
V
⋅
I
R
⋅
V
DAC
R
R
⋅
FB
PWMRMP
I
⋅
CE
FB
O
f
)
⋅
1
SW
⋅
V
)
⋅
G
2
=
(
PWMRMP
V
V
⋅
CS
⋅
CP and
V
V
CP and
O
I
2
3
_
PWMRMP
−
o
⋅
R
ROOM
2
V
FB
SCOMP
π
DAC
⋅
C
f
C
⋅
)
CI
R
CP
CP
LE
⋅
. 1
,
can be determined by equations (27) and (28).
can be determined by equations (29) and (30), where C
⋅
05
1 [
+
⋅
10
2
π
6
⋅
FB
f
CI
from Equations (32).
⋅
C
E
⋅
(
V
O
I
O
)]
⋅
F
MI
CI
(29)
) based on the crossover
(30)
(34)
(27)
(28)
(31)
(32)
(33)
IR3082PbF
01/31/05
CP1
is optional
E