TDA8512 datasheet(8/24 Pages) PHILIPS

8 / 24 page

2001 Nov 16

Philips Semiconductors

Preliminary speciﬁcation

26 W BTL and 2

× 13 W SE or

× 13 W SE power ampliﬁer

TDA8512J

11 THERMAL CHARACTERISTICS

In accordance with IEC 60747-1.

The measured thermal resistance of the IC-package (Rth(j-c)) is maximum 1.3 K/W if all four channels are driven. For a

maximum ambient temperature of 60

°C and VP = 15 V, the following calculation for the heatsink can be made:

For the application two SE outputs with 2

Ω load, the measured worst-case sine-wave dissipation is 2 × 7W

For the application BTL output with 4

Ω load, the worst-case sine-wave dissipation is 12.5 W.

So the total power dissipation is Pd(tot) =2 × 7 + 12.5 W = 26.5 W.

At Tj(max) = 150 °C the temperature increase, caused by the power dissipation, is: ∆T = 150 °C − 60 °C=90 °C.

So Pd(tot) × Rth(tot) = ∆T = 90 K. As a result:

which means:

Rth(hs) =Rth(tot) − Rth(j-c) = 3.4 − 1.3 = 2.1 K/W.

The above calculation is for application at worst-case (stereo) sine-wave output signals. In practice, music signals will be

applied. In that case the maximum power dissipation will be about the half the sine-wave power dissipation, which allows

the use of a smaller heatsink.

So Pd(tot) × Rth(tot) = ∆T = 90 K. As a result:

which means:

Rth(hs) =Rth(tot) − Rth(j-c) = 6.8 − 1.3 = 5.5 K/W.

SYMBOL

PARAMETER

CONDITIONS

VALUE

UNIT

Rth(j-a)

thermal resistance from junction to ambient

in free air

40.0

K/W

Rth(j-c)

thermal resistance from junction to case

see Fig.5

1.3

K/W

th tot

()

26.5

-----------

3.4 K/W

th tot

()

13.25

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

6.8 K/W

handbook, halfpage

3.0 K/W

0.7 K/W

3.0 K/W

virtual junction

output 1

output 2

case

3.0 K/W

0.7 K/W

3.0 K/W

output 3

output 4

MEA860 - 2

0.2 K/W

Fig.5 Equivalent thermal resistance network.

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