ir3088a International Rectifier Corp., ir3088a Datasheet - Page 27

• Manufacturer Part Number: ir3088a
• Description: Xphase Ic With Fault And Overtemp Detect
• Manufacturer: International Rectifier Corp.

IR3088A EXTERNAL COMPONENTS
PWM Ramp Resistor R
Set PWM ramp magnitude V
resistor R
Inductor Current Sensing Capacitor C
Choose 47nF for capacitor C
The bias currents of CSIN+ and CSIN- are 0.25uA and 0.4uA respectively. Calculate resistor R
Combined Over Temperature and Phase Delay Setting Resistors R
The over temperature setting resistor divider is combined with the phase delay resistor divider. Set the temperature
threshold at 115 ºC, which corresponds to the IC die temperature of 116 ºC, and calculate the HOTSET threshold
voltage corresponding to the temperature thresholds.
The phase delay resistor ratios for phases 1 to 6 at 800kHz of switching frequencies are RA
RA
slope.
The over temperature setting voltage of phases 1, 2, 5, and 6 is lower than the phase delay setting voltage,
VBIAS*RA
R
R
R
The over temperature setting voltage of Phases 3 and 4 is higher than the phase delay setting voltage,
VBIAS*RA
V
R
R
R
R
R
R
R
CS
HOTSET
PHASE21
PHASE51
PHASE61
PWMRMP
PHASEx
PHASEx
PHASE
CS
PHASE
PHASE2
+
−
Page 27 of 33
=
=
33
32
3
2
L
C
R
=
=
=
=
CS
CS
=
=
=
12
PWMRMP
R
=10kΩ, R
=10kΩ, R
=10kΩ, R
=0.432, RA
. 4
PHASEx.
V
PHASEx.
(
L
+
+
V
RA
(
RA
V
V
∗
BIAS
73
IN
=
=
HOTSET
800
HOTSET
PHASE
PHASEx
*
*
. 4
100
10
*
V
22
f
*
1 (
SW
BIAS
10
,
−
*
k
3
Pre-select R
V
Pre-select R
3
−
PHASE22
PHASE52
PHASE62
10
Ω
∗
∗
*
BIAS
−
3
∗
∗
47
RA
R
V
C
−
V
∗
T
PHASE3
RA
−
V
PHASEx
BIAS
9
V
PWMRMP
100
BIAS
J
*
PHASEx
BIAS
∗
/(
HOTSET
PWMRMP
10
PHASE
+
1 (
0
. 1
*
*
5 .
−
−
−
=2.94kΩ, R
=2.32kΩ, R
=8.25kΩ, R
10
9
−
R
1
241
V
*
CS+,
=0.198, RA
RA
)
PHASE
PWMRMP
V
3
10
HOTSET
−
*
=
HOTSET
∗
PHASEX1
PHASE11
[ln(
12
PHASEx
=
−
V
. 1
6
3
and Capacitor C
BIAS
and calculate R
. 4
)
8 .
31
∗
79
V
. 1
[ln(
=
73
*
IN
* )
=
28
∗
. 4
1 (
)
)
=0.75V. Choose 100pF for PWM ramp capacitor C
*
12
−
12
R
∗
. 0
22
10
−
PHASE23
PHASE53
PHASE63
=10kΩ,
=10kΩ,
V
PHASEx
V
R
198
.
PHASE4
CS+
. 0
* 1
O
DAC
−
k
PHASE
−
Ω
3
665
. 1
6
10
∗
∗
) 3
8 .
)
and Resistors R
116
6
1
3
−
)
−
31
8 .
−
=
ln(
=
=4.64kΩ
=4.42kΩ
=6.49kΩ
=0.206, RA
. 1
ln(
∗
+
(
=
. 7
79
CS+,
10
V
. 0
12
. 1
87
. 1 (
PWMRMP
IN
665
*
241
−
k
79
10
−
Ω
1
6
V
∗
3
3 .
8 .
=
−
DAC
6
=
. 0
. 1
−
8 .
∗
. 2
. 0
1 (
198
79
PHASE5
6
−
−
8 .
67
75
. 1
−
V
V
CS+
−
. 0
PWMRMP
79
∗
)]
k
. 1
Ω
. 6
665
)
=
79
) 8
∗
=0.401 and RA
and R
18
10
)
∗
.
10
k 2
)]
*
10
*
PHASEx1,
Ω
10
CS-
3
=
3
12
=
1 .
887
k
R
Ω
PHASE6
Ω
PHASEx2
=0.597 starting from down-
PWMRMP
and R
CS-
IR3088A
PHASEx3
, and calculate the
,
1/15
PHASE1
/05
=0.665,