STA533WF

Heatsink requirements

Doc ID 17658 Rev 2

11/15

4

Heatsink requirements

Using the STA533WF mounted on a double-layer PCB having 2 copper ground areas of

24 °C/W in natural air convection.

Figure 8.

Double-layer PCB with copper ground areas and 16 via holes

With the dissipated power within the device depending primarily on the supply voltage, the

load impedance and the output modulation level, the maximum estimated dissipated power,

Pdmax, for the STA533WF is:

4 W for 2 x 20 W into 8

Ω at 18 V

< 5 W for 2 x 10 W into 8

Ω + 1 x 20 W into 4 Ω at 18 V.

The figure below shows the power derating curve for the PowerSSO36 EPD package on

Figure 9.

Power derating curves for PCB used as heatsink

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

TDA7491P

PSSO36

Copper Area 3x3 cm

and via holes

STA533WF

PowerSSO36