IR3521MTRPBF International Rectifier, IR3521MTRPBF Datasheet - Page 35

• Manufacturer Part Number: IR3521MTRPBF
• Description: IC CTRL XPHASE3 SVID 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3521MTRPBF

• Applications: Processor
• Current - Supply: 10mA
• Voltage - Supply: 4.75 V ~ 7.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: *
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Type III Compensation for AVP Applications
Determine the compensation at no load, the worst case condition. Assume the RC, resistor and capacitor across
the output inductors, and L/DCR time constant matches, the crossover frequency and phase margin of the voltage
loop can be estimated by (22) and (23), where R
Choose the desired crossover frequency fc around fc1, estimated by (22), or choose fc between 1/10 and 1/5 of
the switching frequency per phase. The components should be selected to ensure the close loop gain slope is
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 (29), and
determine the component values based on (30) to (34),
-20dB /Dec around the crossover frequency. Choose resistor R
DRP
CP
CP1
and C
is optional and may be needed in some applications to reduce the jitter caused by the high frequency noise.
from (25) and (26).
DRP
CP
and capacitor C
have limited effect on the crossover frequency, and are used only to fine tune the crossover

C
C
C
C
C
R
R
K
R
f
C
C
CP
CP
CP
CP
FB
FB
CP
DRP
1
1

1
1




tan[





90
2

R
2 (
4
10
2

2
1
2


FB
(



4

*
R
R




C


A
FB

FB
f
f
R
(
E
2 (
K
f
tan(
C
f
C
1
L
180
C
C

DRP
CP



E


)
C

R
1
G
R
2
R
R
R

. 0

K
DRP
CS

FB

DRP
FB
CP
C
) 5
are not needed. Choose the crossover frequency fc between 1/10 and 1/5 of
L
1

to
1
1
V
E
L
*
E
5 .
)

R
I
E
R
V


)]
CP
180

FB
I

C
C
C

E
FB

E
K
R

R

FB
R
LE
FB
f
1
C

)
LE

2
5
2
3

is the equivalent resistance of inductor DCR.
5
R
CP
Page 35
FB
and C
CP
from (27) and (28).
FB1
according to (24), and determine C
(22)
(23)
(24)
(25)
(26)
(27)
(28)
(29)
(30)
(31)
(32)
IR3521
V3.03
FB
and