TDA8954 NXP Semiconductors, TDA8954 Datasheet - Page 25

• Manufacturer Part Number: TDA8954
• Description: The TDA8954 is a stereo or mono high–efficiency Class D audio power amplifier in asingle IC featuring low power dissipation
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8954_1
Product data sheet
Power dissipation (P) is determined by the efficiency of the TDA8954.
In the following example, a heatsink calculation is made for an 4 Ω SE application with a
±30 V supply:
When the maximum expected ambient temperature is 50 °C, the total R
R
So the thermal resistance between heatsink and ambient temperature is:
(
-------------------------
R
148 50
Fig 12. Derating curves for power dissipation as a function of maximum ambient
th(j-a)
The audio signal has a crest factor of 10 (the ratio between peak power and average
power (20 dB); this means that the average output power is
Thus, the peak RMS output power level is the 0.5 % THD level, i.e. 92.5 W per channel.
The average power is then
The dissipated power at an output power of 9.25 W is approximately 9.5 W.
R
R
mounting)
th j a
(
9.5
th(j-c)
th(c-h)
–
–
(1) R
(2) R
(3) R
(4) R
(5) R
= R
)
=
(thermal resistance from junction to case) = 0.9 K/W
(thermal resistance from case to heatsink) = 0.5 K/W to 1 K/W (dependent on
)
temperature
th(j-c)
th(j-a)
th(j-a)
th(j-a)
th(j-a)
th(j-a)
T
----------------------
=
j
–
10.3 K/W
P
= 5 K/W.
= 10 K/W.
= 15 K/W.
= 20 K/W.
= 35 K/W.
T
+ R
amb
th(c-h)
Rev. 01 — 24 December 2009
(W)
P
30
20
10
+ R
0
0
th(h-a)
1
⁄
10
20
× 92.5 W = 9.25 W per channel.
(1)
(2)
(3)
(4)
(5)
40
60
2 × 210 W class-D power amplifier
80
T
amb
mbl469
(°C)
100
1
⁄
10
of the peak power.
TDA8954
© NXP B.V. 2009. All rights reserved.
th(j-a)
becomes
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