ir3086mtr International Rectifier Corp., ir3086mtr Datasheet - Page 15

• Manufacturer Part Number: ir3086mtr
• Description: Xphasetm Phase Ic With Ovp, Fault And Overtemp Detect
• Manufacturer: International Rectifier Corp.

SR
of VDAC pin as shown in Figure15 of IR3081 Data Sheet.
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/°C, and therefore the maximum inductor DCR can be calculated from Equation
(10), where R
T_
The current sense amplifier gain of IR3086 decreases with temperature at the rate of 1470 ppm/°C, 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 of IR3081 Data Sheet. K
average current in each phase and is calculated from Equation (14).
No Load Output Voltage Setting Resistor R
A resistor between FB pin and the converter output is used to create output voltage offset V
difference between V
lowers the converter voltage by R
R
also affected by the adaptive voltage positioning resistor R
amplifiers. R
FB
CS_OFST)
ROOM
UP
is not only determined by I
is proportional to that of VDAC down-slope and is given by Equation (9), where I
Page 15 of 34
respectively.
of the amplifier itself and that created by the amplifier input bias currents flowing through the current
FB
L_MAX
and R
CS+
OCSET,
V
G
R
R
K
C
R
SR
and R
CS
OCSET
L
CS
DRP
and R
P
VDAC
VDAC
DAC
_
UP
_
=
MAX
_
TOFST
MIN
(
=
V
are determined by (15) and (16) respectively.
=
=
the bias current of OCSET pin, changes with switching frequency setting resistor R
=
voltage and output voltage at no load condition. Adaptive voltage positioning further
L_ROOM
I
CS-
I
=
0
C
=
[
−
SR
SOURCE
5 .
I
R
=
V
VDAC
I
G
LIMIT
.
FB
SINK
L
O
DOWN
V
+
n
CS
_
CS
)
, the current flowing out of FB pin as shown in Figure 14 of IR3081 Data Sheet, but
O
3
ROOM
∗
CS_TOFST
OCSET
_
2 .
*I
C
_
V
ROOM
are the inductor DCR at maximum temperature T
∗
OFST
O
VDAC
O,
∗
R
I
O
10
/(
L
where R
∗
L
_
/
−
1 [
+
2
∗
MAX
n
∗
15
1 [
I
V
+
CSIN
) of current sense amplifier in phase ICs is the sum of input offset
I
−
3850
∗
∗
1470
FB
1 (
+
f
O
SW
+
∗
and Adaptive Voltage Positioning Resistor R
*
is the required output impedance of the converter.
R
K
∗
*
10
CS
P
10
) 2
)
−
+
OCSET
6
+
−
IC_MAX
−
6
∗
V
I
∗
CS
(
CSIN
T
(
T
L
_
_
IC
TOFST
as defined in Equation (13), where I
−
MAX
_
is calculated from Equation (11).
∗
DRP
MAX
R
CS
]
−
∗
−
T
−
G
and total input offset voltage of current sense
ROOM
T
CS
ROOM
_
P
MIN
)]
is the ratio of inductor peak current over
)]
/
I
OCSET
L_MAX
SOURCE
(10)
(11)
(12)
(13)
(14)
and room temperature
(7)
(8)
(9)
O_NLOFST,
is the source current
LIMIT
DRP
9/30
IR3086
is the required
/04
which is the
OSC