ir3082pbf International Rectifier Corp., ir3082pbf Datasheet - Page 25

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

DESIGN EXAMPLE ― 5-PHASE OPTERON CONVERTER
SPECIFICATIONS
Input Voltage: V
DAC Voltage: V
No Load Output Voltage Offset: V
Maximum Output Current: I
Output Impedance: R
Soft Start Time: t
Dynamic VID Down-Slope Slew Rate: SR
Over Temperature Threshold: T
POWER STAGE
Phase Number: n=5
Switching Frequency: f
Output Inductors: L=220 nH, R
Output Capacitors: C=47uF, R
IR3082PbF EXTERNAL COMPONENTS
Oscillator Resistor Rosc
Once the switching frequency is chosen, R
frequency of 600kHz per phase, choose R
Soft Start Capacitor C
Calculate the soft start capacitor from the required soft start time.
The soft start delay time is
VDAC Slew Rate Programming Capacitor C
From Figure 15, the sink current of VDAC pin corresponding to 600kHz (R
VDAC down-slope slew-rate programming capacitor from the required down-slope slew rate.
Calculate the programming resistor.
C
t
t
C
R
VccPG
OCDEL
VDAC
VDAC
SS
/
DEL
=
=
=
=
C
0
=
SR
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C
5 .
SS
I
I
SS
SINK
DOWN
+
CHG
/
I
/
DEL
DISCHG
V
DEL
3
O
2 .
C
⋅
⋅
VDAC
t
⋅
=
DAC
⋅
(
I
SS
=12 V
. 0
10
. 3
SS
I
2
CHG
09
73
=
−
5 .
2
15
=1.3 V
= 2 mS
125
1
⋅
−
=
10
O
3 .
=
66
V
SW
=0.75 mΩ
C
SS/DEL
⋅
+
O
−
0
10
3
⋅
5 .
SS
10
(
−
=600 kHz
/
50
6
−
/
10
. 1
+
OMAX
DEL
6
⋅
−
10
6
) 3
−
(
−
3
47
⋅
6
15
2 .
C
2
⋅
−
L
=
. 0
6
=
PCB
=0.42 mΩ
= 2mΩ, Number Cn=32
⋅
⋅
)
⋅
=100 ADC
10
10
09
0
10
⋅
50
O_NLOFST
10
1 .
−
−
−
nF
=115 ºC
3
9
=
⋅
15
−
10
)
3
2
1
, Choose C
=
5 .
−
=
6
ms
. 0
2
⋅
DOWN
(
66
Ω
OSC
0988
. 3
=15mV
73
⋅
10
OSC
=18.2kΩ
VDAC
uF
−
=2.5mV/uS
−
. 1
6
335
VDAC
, choose
can be determined from the curve in Figure 13. For switching
and Resistor R
−
. 1
=47nF
) 3
=
C
. 1
SS
64
/
DEL
ms
=
VDAC
0
1 .
uF
OSC
=18.2kΩ) is 125uA. Calculate the
IR3082PbF
01/31/05