July 1994 5
Philips Semiconductors Product specification
2 x 6 W hi-fi audio power amplifier TDA1521ATHERMAL RESISTANCE
HEATSINK DESIGN EXAMPLE
With derating of 6 K/W, the value of heatsink thermal resistance is calculated as follows:
given RL = 8Ωand VP=±12 V, the measured maximum dissipation is 7,8 W; then, for a maximum ambient temperature
of 60 °C, the required thermal resistance of the heatsink is
Note: The metal tab (heatsink) has the same potential as pin 5 ( − VP).
From junction to case Rth j-c = 6 K/W
Fig.2 Power derating curve.
Rthh-a 150 60–
78,
---------------------- 6 5,5 K/W=–=