TDA8922C
NXP Semiconductors
2 × 75 W class-D power amplifier
Equation 5 defines the relationship between maximum power dissipation before activation
of TFB and total thermal resistance from junction to ambient.
(5)
T j – Tamb
Rth
=
-----------------------
(j–a)
P
Power dissipation (P) is determined by the efficiency of the TDA8922C. 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.
mbl469
30
P
(W)
(1)
20
(2)
10
(3)
(4)
(5)
0
0
20
40
60
80
T
100
(°C)
amb
(1) Rth(j-a) = 5 K/W.
(2) Rth(j-a) = 10 K/W.
(3) Rth(j-a) = 15 K/W.
(4) Rth(j-a) = 20 K/W.
(5) Rth(j-a) = 35 K/W.
Fig 9. Derating curves for power dissipation as a function of maximum ambient
temperature
TDA8922C_1
© NXP B.V. 2009. All rights reserved.
Product data sheet
Rev. 01 — 7 September 2009
19 of 40
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