IR3094M International Rectifier Corp., IR3094M Datasheet - Page 21

• Manufacturer Part Number: IR3094M
• Description: 3 Phase Pwm Controller For Point Of Load
• Manufacturer: International Rectifier Corp.

Type II Compensation for Voltage Droop Applications
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, and determine R
the equivalent inductance of output inductors and the equivalent capacitance of output capacitors respectively.
C
ceramic capacitor between 10pF and 220pF is usually enough.
Type III Compensation for Voltage Droop 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 (18) and (19), where R
Choose the desired crossover frequency fc around fc1 estimated by (18) 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 /Dec
around the crossover frequency. Choose resistor R
and (22).
CP1
is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise. A
VO+
VDRP
Page 21 of 29
RFB
RDRP
(
a) Type II compensation
R
VREF
T
VDAC
f
CP
C
C
FB
FB
C
RCP
1
1
CP
Figure 9. Voltage loop compensation networks
2 (
90
V
2
+
-
CCP1
S
I
S
10
 A
*
*
EAOUT
C
f
1
E
tan(
C
CCP

R
)
L
2
2 (
CP
G
E
R
. 0
S
CS
DRP
L
) 5
*
C
E
*
EAOUT
f
E
R
C
180
FB1
C
FB
S
*
E
C
LE
according to (20), and determine C
*
R
R
R
is the equivalent resistance of inductor DCR.
LE
FB
VO+
VDRP
C
RFB1
)
CP
2
5
(b) Type III compensation
and C
RFB
RDRP
CFB
CDRP
CP
from (16) and (17), where L
VDAC
VREF
FB
RCP
(18)
(19)
+
-
CCP1
(16)
(17)
EAOUT
CCP
FB
IR3094PBF
and C
09/26/05
EAOUT
DRP
E
and C
from (21)
E
are