THERMAL SHUTDOWN

The presence of a thermal limiting circuit offers

the following advantages:

1)An overload on the output (even if it is perma-

nent), or an above limit ambient temperature

can be easily tolerated since the Tj cannot be

higher than 150

°C.

2)The heatsink can have a smaller factor of

safety compared with that of a conventional

circuit. There is no possibility of device dam-

age due to high junction temperature.

If for any reason, the junction temperature in-

crease up to 150

°C, the thermal shutdown

simply reduces the power dissipation and the

current consumption.

The maximum allowable power dissipation de-

pends upon the junction-ambient thermal resis-

tance. Fig. 21 shows this dissipable power as a

function of ambient temperature for different ther-

mal resistance.

Figure 21: Maximum Allowable Power

Dissipation vs. Ambient Temperature

Figure 22: Example of Heatsink using PC Board

Copper (l = 65mm)

MOUNTING INSTRUCTIONS

The TDA7245 is assembled in the POWERDIP, in

which 9 pins (from 10 to 18) are attached to the

frame and remove the heat produced by the chip.

Figure 22 shows a PC Board copper area used

as a Heatsink (l = 65mm). The Thermal Resis-

tance Junction-Ambient is 35

°C.

TDA7245

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