TDA7497SA Datasheet, PDF (6/10 Pages) STMicroelectronics – 8W+8W+15W TRIPLE AMPLIFIER

TDA7497SA
3 HEAT SINK DIMENSIONING:
In order to avoid the thermal protection intervention, that is placed approximatively at T_j = 150°C, it is important
the dimensioning of the Heat Sinker R_Th (°C/W).
The parameters that influence the dimensioning are:
– Maximum dissipated power for the device (P_dmax)
– Max thermal resistance Junction to case (R_{Th j-c})
– Max. ambient temperature T_{amb max}
– Quiescent current I_q (mA)
3.1 Example:
V_CC = 28V, R_load = 8ohm (left/right), Rload = 4ohm (centre), R_{Th j-c} = 2.5°C/W , T_{amb max} = 50°C
P_dmax
=
(N°
channels)
·
----------^V----^c---^c--²-----------
2Π² ⋅ R_load
+
I_q
⋅
V_cc
P_dmax = 2 · ( 3.95 ) + 1 · ( 7.9 ) + 1.2 = 17W
(Heat Sinker)
R_{Th c-a}
=
1_----5_---0_{-----–-----}T_{---a---m-----b----m----a---x-}
P_{d max}
–
R_Th
j-c
=
1_----5_---0_{-----–----}5_----0_--
17
–
2.5
=
3.3 ° C /W
In figure 6 is shown the Power derating curve for the device.
Figure 11. Power Derating Curve
35
30
25
20
15
10
5
0
0
(a)
(c)
(b)
(d)
a) Infinite Heatsink
b) 1.5 °C/ W
c) 3.0 °C/ W
d) 5.0 °C/ W
40
80
120
160
Tamb (°C)
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