iP2003
Calculating SOA Temperature:
(Fig. 3)
(Fig. 4)
(Fig. 5)
(Fig. 6)
SOA Temperature Adjustment for input voltage ≈ -0.5°C
SOA Temperature Adjustment for output voltage ≈ 3.3°C
SOA Temperature Adjustment for frequency ≈ -1.2°C
SOA Temperature Adjustment for inductor value ≈ 0.25°C
TX axis intercept temp adjustment = - 0.5°C + 3.3°C - 1.2°C + 0.25°C ≈ 1.85°C
Assuming TCASE = 110°C & TPCB = 100°C:
The following example shows how the SOA current is adjusted for a TX increase of 1.85°C.
0
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
0
Case Temperature (°C)
10
20
30
40
50
60
70
80
90
100
110
120
TX
VIN = 12V
VOUT = 1.3V
fSW = 1MHz
L=0.3uH
Safe
Operating
Area
10
20
30
40
50
60
70
80
90
100
110
120
PCB Temperature (ºC)
PIN = VIN Average x IIN Average
PDD = VDD Average x IDD Average
POUT = VOUT Average x IOUT Average
PLOSS = (PIN + PDD) - POUT
Average
VDD
Current
(IDD)
A
Average
VDD
V DC
Voltage
(VDD)
PRDY
ENABLE
PWM
VDD
VIN
VSW
PGND
iP2003
Average
Input
Current
(IIN)
A
DC
Average
V
Input
Voltage
(VIN)
Average Output
Current (IOUT)
A
Averaging
Circuit
Average
V
Output
Voltage
(VOUT)
Fig. 8: Power Loss Test Circuit
6
90%
PWM
10%
90%
VSW
10%
td(on)
td(off)
Fig. 9: Timing Diagram
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