STCS1A Application information
13/19
– LEDs current: 500 mA;
– Package: DFN8 3x3 mm;
–T
A
= 50°C;
In this case V
DRAIN
= 12 - 3 x 3.6 = 1.2 V
P
D
= (1.2 - 0.1) x 0.5 + 12 x 0.5 x 10
-3
= 0.55 + 6 x 10
-3
= 556 mW
The junction temperature will be:
T
J
= 37.6 x 0.556 + 50 = 70.9 °C
The following pictures show the maximum power dissipation according to the ambient
temperature for both packages:
Figure 16. Maximum power dissipation vs T
A
for DFN8 3x3 mm
Figure 17. Maximum power dissipation vs T
A
for PowerSO-8
R
thJA
= 38 [°C/W]
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
25 35 45 55 65 75 85 95 105 115 125
[°C]
P
DMAX
[W]
P
DMAX
= (T
JMAX
-T
A
)/R
thJA
R
thJA
= 38 [°C/W]
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
25 35 45 55 65 75 85 95 105 115 125
[°C]
P
DMAX
[W]
P
DMAX
= (T
JMAX
-T
A
)/R
thJA
0.00
0.50
1.00
1.50
2.00
2.50
3.00
25 35 45 55 65 75 85 95 105 115 125
[°C]
P
DMAX
= (T
JMAX
-T
A
)/R
thJA
R
thJA
= 45 [°C/W]
P
DMAX
[W]
0.00
0.50
1.00
1.50
2.00
2.50
3.00
25 35 45 55 65 75 85 95 105 115 125
[°C]
P
DMAX
= (T
JMAX
-T
A
)/R
thJA
R
thJA
= 45 [°C/W]
P
DMAX
[W]
