IR3084AMPBF International Rectifier, IR3084AMPBF Datasheet - Page 39

• Manufacturer Part Number: IR3084AMPBF
• Description: IC XPHASE CONTROL 28-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase™r

Specifications of IR3084AMPBF

• Applications: Processor
• Current - Supply: 14mA
• Voltage - Supply: 9.5 V ~ 16 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 28-MLPQ
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Phase Delay Timing Resistors RPHASEx1 to RPHASEx2 (x=1,2,…,7)
The phase delay resistor ratios for phases 1 to 7 at 400kHz are (from the X−Phase Excel based design
spreadsheet); RAPHASE1=0.580, RAPHASE2=0.397, RAPHASE3=0.215, RAPHASE4=0.206,
RAPHASE5=0.353 RAPHASE6=0.5 and RAPHASE7=0.647.
Pre−select RPHASE11=RPHASE21=RPHASE31=RPHASE41=RPHASE51=RPHASE61=RPHASE71=20kΩ,
Calculating the other resistors from the same formula results in; R
R
Phase ICs 1−3 should have the RMPOUT voltage from the 3084A controller connected to their RMPIN− pin so
they will trigger on the negative slope of the RMPOUT waveform. Phase ICs 4−7 should have the RMPOUT
voltage from the 3084A controller connected to their RMPIN+ pin so they will trigger on the positive slope of the
RMPOUT waveform.
Bootstrap Capacitor C
Choose C
Decoupling Capacitors for Phase IC and Power Stage
Choose C
VOLTAGE LOOP COMPENSATION
AL−Polymer output capacitors are used in the design, for instructional purposes Type III compensation as shown
in Figure 18(b) will be demonstrated here. First, choose the desired crossover frequency as 1/10 of the switching
frequency, f
PHASE42
Choose C
C
C
R
R
CP
CP
FB
FB
Page 39 of 45
1
R



=5.2kΩ, P

BST
VCC
PHASE
2 (
10
C
4

1
2


=40 kHz, and determine Rcp and C
=0.1uF.
=0.1uF, C
CP1
. 2
*
*
12
*
*
R
49
R
f
f
=100pF to reduce high frequency noise.

FB
L
C
C
1
K
CP
PHASE52
E
1
)
*


2

*
RA
R
*
C
1
2
RA
VCCL
BST
FB
L
PHASE
E
*
E
1
PHASE
324
*
=10.9kΩ, R


V
=0.1uF
C
1
10
o
4
E


1
*
*

162
*
R
R
40
FB
(
PHASE
220

*
*
PHASE62
1
10
V
11
*
PWMRMP
3
10

*
. 2
162

1
9
=20kΩ, R
49

. 0
CP
/
Choose R

) 7
. 0
58
*

2 (
using Equations (30) and (31):
58
10
( *
12

3
560
3 .

*
PHASE72
20
nF
40
FB1
*
*
*
10
=162Ω
10
10

3
6
3
=36.6kΩ.
PHASE22
)
*

2
10
( *
27
. 1
)
30
220
6 .

Choose C
k
=13.2kΩ, R


53
*
. 0
10
nF
015

9
,
/

) 7
FB
130
PHASE32
( *
=10nF
560
*
Choose C
* 1
*
10
=5.48kΩ,
10
IR3084A

3/3/2009
3

6
*
CP
10
=56nF
* )
324
*
0
8 .