IR3081 International Rectifier Corp., IR3081 Datasheet - Page 30

• Manufacturer Part Number: IR3081
• Description: Xphasetm Vr 10 Control Ic
• Manufacturer: International Rectifier Corp.

VDAC Slew Rate Programming Capacitor C
From Figure 15, the sink current of VDAC pin corresponding to 800kHz (R
VDAC down-slope slew-rate programming capacitor from the required down-slope slew rate.
Calculate the programming resistor.
From Figure 15, the source current of VDAC pin is 250uA. The VDAC up-slope slew rate is
Over Current Setting Resistor R
The room temperature is 25ºC and the target PCB temperature is 100 ºC. The phase IC die temperature is about 1
ºC higher than that of phase IC, and the inductor temperature is close to PCB temperature.
Calculate Inductor DC resistance at 100 ºC,
The current sense amplifier gain is 34 at 25ºC, and its gain at 101ºC is calculated as,
Set the over current limit at 135A. From Figure 14, the bias current of OCSET pin (I
R
the current sense amplifier input resistor mismatch.
Calculate constant K
No Load Output Voltage Setting Resistor R
From Figure 14, the bias current of FB pin is 90uA with R
C
G
R
SR
R
K
R
=
R
R
L
OSC
OCSET
VDAC
VDAC
FB
DRP
CS
P
(
UP
_
135
MAX
=
Page 30 of 39
_
6
=
MIN
=13.3kΩ. The total current sense amplifier input offset voltage is 0.55mV, which includes the offset created by
=
=
(
V
R
=
=
∗
=
=
I
R
I
L
. 0
0
C
SR
SOURCE
−
[
_
FB
=
R
5 .
VDAC
64
R
I
MAX
V
L
G
SINK
DOWN
LIMIT
∗
+
O
_
n
*
CS
R
ROOM
)
3
10
∗
∗
L
2 .
C
_
V
V
_
I
n
=
ROOM
−
VDAC
∗
O
*
O
MAX
LIMIT
3
=
∗
∗
R
10
250
_
/(
∗
68
R
1 [
L
I
NLOFST
2
. 1
L
FB
−
O
_
5 .
P,
∗
2
+
*
15
∗
32
∗
/
MAX
170
*
G
10
*
3850
∗
V
10
the ratio of inductor peak current over average current in each phase,
n
1 [
CS
10
=
I
R
+
−
−
−
∗
*
L
9
∗
0
. 0
−
_
−
6
1470
_
10
5 .
*
MIN
3
f
1 (
V
55
MAX
SW
10
=
/
CS
+
+
−
10
3
6
−
*
∗
K
_
(
7 .
6
*
=
10
−
3
68
TOFST
∗
10
) 2
P
6
mV
2 .
162
(
)
−
T
*
OCSET
=
−
*
+
3
=
L
10
6
* )
10
V
68
_
/
∗
∗
(
6
∗
MAX
12
CS
uS
−
. 0
∗
(
30
−
nF
n
9
T
15
64
_
. 0
)
−
∗
IC
2 .
2
TOFST
−
91
. 1
R
*
_
T
=
/(
O
28
10
MAX
*
ROOM
90
1
10
=
)
2 .
−
]
FB
3
VDAC
∗
∗
*
. 0
Ω
−
*
. 1
−
10
G
3
)]
64
30
and Adaptive Voltage Positioning Resistor R
T
28
CS
=
−
ROOM
*
2 .
6
0
/(
_
and Resistor R
10
)
5 .
100
MIN
=
=
−
*
135
576
3
)]
. 6
10
*
∗
/
OSC
34
=
10
I
−
20
6 /
Ω
3
OCSET
34
90
k
∗
−
*
Ω
9
=13.3kΩ.
1 [
10
∗
*
∗
+
10
1 [
12
−
3850
3
−
−
∗
−
6
1470
800
*
. 0
VDAC
*
. 0
55
10
64
*
*
*
−
10
10
6
10
*
∗
10
3
−
(
−
∗
6
100
3
−
) 2
∗
∗
3
OSC
(
6
101
−
=
∗
25
. 0
=13.3kΩ) is 170uA. Calculate the
. 0
−
)]
32
91
25
=
*
. 0
)]
10
64
=
−
3
m
30
Ω
=
2 .
162
OCSET
Ω
DRP
10/01
) is 90uA with
IR3081
/04