Datasheet
STA333ML Package thermal characteristics
Doc ID 13177 Rev 6 17/21
6 Package thermal characteristics
Using a double layer PCB the thermal resistance junction to ambient with 2 copper ground
areas of 3 x 3 cm
2
and with 16 via holes (see Figure 13) is 24 °C/W in natural air convection.
The dissipated power within the device depends primarily on the supply voltage, load
impedance and output modulation level.
The max estimated dissipated power for the is:
Figure 13. Double layer PCB with 2 copper ground areas and 16 via holes
Figure 14 shows the power derating curve for the PowerSSO-36 package on a board with
two copper areas of 2 x 2 cm
2
and 3 x 3 cm
2
.
Figure 14. PowerSSO-36 power derating curve
2 x 20 W into 8 Ω, at 18 V Pd max is approximately 4 W
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Pd (W)
Tamb ( °C)
Copper Area 2x2 cm
and via holes
STA333BW
PSSO36
Copper Area 3x3 cm
and via holes
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Pd (W)
Tamb ( °C)
Copper Area 2x2 cm
and via holes
STA333ML
PSSO36
Copper Area 3x3 cm
and via holes
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Pd (W)
Tamb ( °C)
Copper Area 2x2 cm
and via holes
STA333BW
PSSO36
Copper Area 3x3 cm
and via holes
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
20 40 60 80 100 120 140 160
Pd (W)
Tamb ( °C)
Copper Area 2x2 cm
and via holes
STA333BW
PSSO36
Copper Area 3x3 cm
and via holes
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Pd (W)
Tamb ( °C)
Copper Area 2x2 cm
and via holes
STA333ML
PSSO36
Copper Area 3x3 cm
and via holes
STA333ML
PowerSSO-36