Datasheet

STA559BW Package thermal characteristics
Doc ID 18190 Rev 1 63/67
8 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 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.
Thus, the maximum estimated dissipated power for the STA559BW is:
Figure 20 shows the power derating curve for the PowerSSO-36 package on PCBs with
copper areas of 2 x 2 cm
2
and 3 x 3 cm
2
.
Figure 20. PowerSSO-36 power derating curve
2 x 20 W @ 8 Ω, 18 V Pd max is approximately 4 W
2 x 9 W + 1 x 20 W @ 4 Ω, 8 Ω, 18 V Pd max is approximately 5 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
STA339BW
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
STA339BW
PSSO36
Copper Area 3x3 cm
and via holes
STA559BW
PowerSSO-36