6 Thermal Information

STA543SA

20/23

CD00061065

6

Thermal Information

dimensioning.

The parameters that influence the dimensioning are:

●

●

●

Max. Ambient temperature Tamb. Max

There is also an additional term that depends on the Iq (quiescent current).

6.1

Example (A): 2 channels Single Ended + 1Ch (BTL)

Pout = 2 x 7W + 1 x 24W

°C/W

NOTE: The values found gives an heatsinker that is dimensioned to sustain the max. dissipated

power, but as explained in the Application Note (AN1965) the heatsinker can be smaller when

we consider the real application where a musical program is used.

If we consider the so called "Average Listening Dissipated Power" concept we obtain a value

that is about 40% less respect the Pdmax (see AN1965 for reference).

So in the examples (A) and we will obtain the value for the Average Listening Dissipated Power

that is respectively:

In

Figure 15. is shown the Power Derating curve for the device

Figure 15. Power Derating Curve

P

dm ax

2

Vcc

2

2

π

2

R1

------------------

2Vcc

2

π

2

R1

-----------------

+

⋅

22.62

10.5

+

⋅

15.76W

==

=

150

T

am bmax

–

P

dm ax

----------------------------------------

R

TH j

c

–

–

150

50

–

15.76

----------------------

2

–

4.3

==

0

5

10

15

20

25

30

0

20

40

60

80

100

120

140

160

1) Infinite

2) 3.5°C/W

3) 5C/W

4) 7C/W

5) 10C/W

4

1

3

2

Pd(W)

Tamb (°C)

5