TDA2030
SHORT CIRCUIT PROTECTION
The TDA2030 has an original circuit which limits the
current of the output transistors. Fig. 18 shows that
the maximum output current is a function of the
collector emitter voltage; hence the output transis-
tors work within their safe operating area (Fig. 2).
This function can therefore be considered as being
peak power limiting rather than simple current lim-
iting.
It reduces the possibility that the device gets dam-
aged during an accidental short circuit from AC
output to ground.
F i gu r e 1 8. Ma ximum
o u tpu t c urr en t v s .
voltage [V
CEsat
] across
each output transistor
Figure 19. Safe operating area and
collector characteristics of the
protected power transistor
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 abovelimit ambient temperaturecan
be easily supported since the T
j
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 damage due to
high junction temperature.If for any reason, the
junction temperature increases up to 150°C, the
thermal shut-down simply reduces the power
dissipation at the current consumption.
The maximum allowable power dissipation de-
pends upon the size of the external heatsink (i.e. its
thermal resistance); fig. 22 shows this dissipable
power as a function of ambient temperature for
different thermal resistance.
8/11
STMICROELECTRONICS [ STMICROELECTRONICS ]
