ir3082pbf International Rectifier Corp., ir3082pbf Datasheet - Page 20

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

VDAC Slew Rate Programming Capacitor C
The slew rate of VDAC down-slope SR
Equation (7), where I
compensate VDAC circuit and is determined by Equation (8). The slew rate of VDAC up-slope SR
to that of VDAC down-slope and is given by Equation (9), where I
shown in Figure15.
Over Current Setting Resistor R
The inductor DC resistance is utilized to sense the inductor current. The copper wire of inductor has a constant
temperature coefficient of 3850 PPM, and therefore the maximum inductor DCR can be calculated from Equation
(10), where R
T_
The current sense amplifier gain of IR3086A decreases with temperature at the rate of 1470 PPM, which
compensates part of the inductor DCR increase. The phase IC die temperature is only a couple of degrees Celsius
higher than the PCB temperature due to the low thermal impedance of MLPQ package. The minimum current sense
amplifier gain at the maximum phase IC temperature T
The total input offset voltage (V
(V
sense resistors R
The over current limit is set by the external resistor R
over current limit. I
and is determined by the curve in Figure 14. K
phase and is calculated from Equation (14).
CS_OFST)
ROOM
Page 20 of 33
respectively.
of the amplifier itself and that created by the amplifier input bias currents flowing through the current
L_MAX
V
t
C
SR
G
R
R
R
K
SSDEL
CS+
VDAC
CS
VDAC
L
CS
OCSET
P
UP
_
OCSET,
_
_
MAX
=
TOFST
and R
MIN
and R
SINK
=
=
=
(
=
V
=
C
0
I
=
=
I
C
SR
[
SOURCE
5 .
SS
−
=
I
VDAC
R
G
I
is the sink current of VDAC pin as shown in Figure 15. The resistor R
the bias current of OCSET pin, changes with switching frequency setting resistor R
SINK
/
+
LIMIT
V
DOWN
L_ROOM
V
L
CS
CS-
DEL
n
_
O
CS
3
ROOM
_
)
2 .
C
ROOM
.
_
⋅
⋅
VDAC
⋅
V
OFST
1 (
⋅
R
10
O
I
3 .
OCSET
CS_TOFST
L
O
⋅
/(
I
−
1 [
⋅
_
2
−
are the inductor DCR at maximum temperature T
CHG
15
1 [
+
/
MAX
L
n
+
R
I
−
⋅
V
SS
CSIN
3850
1470
⋅
I
/
DOWN
1 (
DEL
⋅
+
+
f
⋅
⋅
) of current sense amplifier in phase ICs is the sum of input offset
SW
⋅
⋅
R
10
K
10
I
CS
CHG
P
⋅
VDAC
−
−
) 2
can be programmed by the external capacitor C
+
)
6
6
P
+
⋅
−
)
⋅
(
(
is the ratio of inductor peak current over average current in each
V
T
=
T
I
CS
CSIN
L
IC
and Resistor R
C
_
_
_
MAX
OCSET
SS
TOFST
MAX
IC_MAX
−
/
⋅
DEL
R
−
−
CS
]
T
T
⋅
⋅
ROOM
−
as defined in Equation (13), where I
1 (
G
ROOM
is calculated from Equation (11).
3 .
CS
66
−
_
)]
)]
MIN
R
⋅
10
SS
VDAC
/
SOURCE
−
/
DEL
6
I
OCSET
⋅
66
⋅
10
is the source current of VDAC pin as
−
6
)
L_MAX
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
IR3082PbF
and room temperature
LIMIT
VDAC
01/31/05
UP
VDAC
is proportional
is the required
as defined in
is used to
OSC