Obsolete

Product(s)

- Obsolete

Product(s)

TDA8139, TDA8139/D

Power dissipation and layout indications

9/14

5

Power dissipation and layout indications

The power is mainly dissipated by the two device buffers. It can be calculated by the

equation:

P = (VIN1-VO1) x IOUT1 + (VIN2-VO2) x IO2

The following table lists the different RthJA values of these packages with or without a

heatsink and the corresponding maximum power dissipation assuming:

Maximum ambient temperature = 70 °C

Maximum junction temperature = 140 °C

Figure 8.

Thermal resistance (junction-to-ambient) of DIP16 package without heatsink

Figure 9.

Metal plate mounted near the TDA8139A for heatsinking

Table 5.

RthJA values with or without heatsinks

Device

Heatsink

RthJA in

°C/W

PMAX in W

TDA8139

No

50

1.4

Yes

20

3.5

TDA8139/D

No

56 to 40

1.25 to 1.75

Yes

32

2.2

Copper area (cm²) (35 µm plus solder) board is face-down

To optimize the thermal conductivity of the

copper layer and the exchanges with the air, the

solder must cover the maximum amount of this

area.

60

40

50

10

12

0

55

45

24

8

6

Test Board with

“On Board” square heat sink area.

Bottom view

Top view