Philips TDA2611A - Heatsink Example and Power Derating

November 1982 4
Philips Semiconductors Product specification
5 W audio power amplifier TDA2611A
Fig.2 Power derating curves.
HEATSINK EXAMPLE
Assume V
P
= 18 V; R
L
= 8 Ω; T
amb
= 60 °C maximum; T
j
= 150 °C (max. for a 4 W application into an 8 Ω load, the
maximum dissipation is about 2,2 W).
The thermal resistance from junction to ambient can be expressed as:
Since R
th j-tab
= 11 K/W and R
th tab-h
= 1 K/W, R
th h-a
= 41 − (11 + 1) = 29 K/W.
R
th j-a
R
th j-tab
R
th tab-h
R
th h-a
150 60–
22,
----------------------
41 K/W.==++=