TDA2052 ST Microelectronics, TDA2052 Datasheet - Page 9

• Manufacturer Part Number: TDA2052
• Description: 60W Hi-Fi AUDIO POWER AMPLIFIER WITH MUTE / STAND-BY
• Manufacturer: ST Microelectronics

SHORT-CIRCUIT PROTECTION
The TDA 2052 has an original circuit which pro-
tects the device during accidental short-circuit be-
tween output and GND / -Vs / +Vs, taking it in
STAND-BY mode, so limiting also dangerous DC
current flowing throught the loudspeaker.
If a short-circuit or an overload dangerous for the
final transistors are detected, the concerned SOA
circuit sends out a signal to the latching circuit
(with a 10 s delay time that prevents fast random
spikes from inadvertently shutting the amplifier
off) which makes Q
Diagram). Q
the A point turning the final stage off while Q
short-circuits to ground the external capacitor
driving the pin 3 (Mute/Stand-by) towards zero
potential.
Only when the pin 3 voltage becomes lower than
1V, the latching circuit is allowed to reset itself
and restart the amplifier, provided that the short-
circuit condition has been removed. In fact, a win-
dow comparator is present at the output and it is
aimed at preventing the amplifier from restarting if
the output voltage is lower than 0.35 Total Supply
Voltage or higher than 0.65 Total Supply Voltage.
If the output voltage lies between these two
thresholds, one may reasonably suppose the
short-circuit has been removed and the amplifier
may start operating again.
The PLAY/MUTE/STAND-BY function pin (pin 3)
is both ground- and positive supply-compatible
and can be interfaced by means of the R
either to a TTL or CMOS output ( -Processor) or
to a specific application circuit.
The R
ing this pin directly to a low output impedance
driver such as TTL gate would prevent the correct
operation during a short-circuit. Actually a final
stage overload turns on the protection latching
circuit that makes Q
under 0.8 V. Since the maximum current this pin
can stand is 3 mA, one must make sure the fol-
lowing condition is met:
that yields: R
In order to prevent pop-on and -off transients, it is
advisable to calculate the C
way that the STAND-BY/MUTE and MUTE/PLAY
threshold crossing slope (positive at the turn-on
and vice-versa) is less than 100 V/sec.
5
, C
3
net is fundamental, because connect-
1
immediately short-circuits to ground
5, min
R
5
= 1.5 K
1
2
and Q
try to drive the pin 3 voltage
V
A
3mA
0.7V
2
3
with V
saturate (see Block
, R
5
A
net in such a
=5V.
5
, C
3
net
2
THERMAL PROTECTION
The thermal protection operates on the 125 A
current generator, linearly decreasing its value
from 90 C on. By doing this, the A voltage slowly
decreases thus switching the amplifier first to
MUTE (at 145 C) and then to STAND-BY
(155 C).
Figure 16: Thermal Protection Block Diagram
The maximum allowable power dissipation de-
pends on the size of the external heatsink (ther-
mal resistance case-ambient); figure 17 shows
the dissipable power as a function of ambient
temperature for different thermal resistance.
Figure 17: Maximum Allowable Power Dissipa-
tion vs. Ambient Temperature.
TDA2052
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