Philips TDA8950 - Heatsink requirements

TDA8950_2 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 02 — 11 June 2009 19 of 39
NXP Semiconductors
TDA8950
2 × 150 W class-D power amplifier
13.5 Heatsink requirements
An external heatsink must be connected to the TDA8950.
Equation 5 defines the relationship between maximum power dissipation before activation
of TFB and total thermal resistance from junction to ambient.
(5)
Power dissipation (P) is determined by the efficiency of the TDA8950. Efficiency
measured as a function of output power is given in Figure 20. Power dissipation can be
derived as a function of output power as shown in Figure 19.
(1) R
th(j-a)
= 5 K/W.
(2) R
th(j-a)
= 10 K/W.
(3) R
th(j-a)
= 15 K/W.
(4) R
th(j-a)
= 20 K/W.
(5) R
th(j-a)
= 35 K/W.
Fig 9. Derating curves for power dissipation as a function of maximum ambient
temperature
R
th
ja–()
T
j
T
amb
–
P
------------------------
=
P
(W)
30
20
10
0
T
amb
(°C)
(1)
(2)
(3)
(4)
(5)
0 20 10040 60 80
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