THERMAL SHUT-DOWN

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

higher than 150

°C.

2) The heatskink can have a smaller factor of

safety compared with that of a conventional

Figure 29. Output power and

d r ai n

c u rr e n t

vs .

c ase

temperature

Figure 30. Output power and

d ra i n

c u rr e nt

vs .

cas e

temperature

Figure31. Maximumallow able

power dissipation vs. ambient

temperature

MOUNTING INSTRUCTIONS

The power dissipated in the circuit must be re-

moved by adding an external heatsink.

Thanks to the Multiwatt

® package attaching the

heatsink is very simple, a screw or a compression

12/14

circuit. There is no possibility of device damage

due to high junction temperature.

If for any reason, the junction temperature in-

creases up to 150

°C, the thermal shut-down

simply reduces the power dissipation and the

current consumption.

The maximum allowable power dissipation de-

pends upon the size of the external heatsink (i.e. its

thermal resistance); fig. 31 shows this dissipable

power as a function of ambient temperature for

different thermal resistance.

spring (clip) being sufficient. Between the heatsink

and the package it is betterto insert a layer of silicon

grease, to optimize the thermal contact; no electri-

cal isolation is needed between the two surfaces.

TDA1910