TDA7561 Datasheet, PDF (8/19 Pages) STMicroelectronics – MULTIFUNCTION QUAD POWER AMPLIFIER WITH BUILT-IN DIAGNOSTICS FEATURES

TDA7561
Figure 12. Power Dissipation vs. Average
Ouput Power (Audio Program
Simulation, 4Ω)
Ptot (W)
45
Figure 13. Power Dissipation vs. Average
Ouput Power (Audio Program
Simulation, 2Ω)
Ptot (W)
90
40
Vs = 14.4 V
35
RL = 4x4 Ohm
GAUSSIAN NOISE
30
25
20
15
10
CLIP
START
80
70 ^{Vs = 14.4 V}
RL = 4x2 Ohm
60
GAUSSIAN NOISE
50
40
30
20
10
CLIP
START
5
0
0
1
2
3
4
5
0
1
2
3
4
5
6
7
8
Po (W)
Po (W)
DIAGNOSTICS FUNCTIONAL DESCRIPTION:
a) TURN-ON DIAGNOSTIC.
It is activated at the turn-on (stand-by out) under I2Cbus request. Detectable output faults are:
- SHORT TO GND
- SHORT TO Vs
- SHORT ACROSS THE SPEAKER
- OPEN SPEAKER
To verify if any of the above misconnections are in place, a subsonic (inaudible) current pulse (fig. 14) is inter-
nally generated, sent through the speaker(s) and sunk back.The Turn On diagnostic status is internally stored
until a successive diagnostic pulse is requested (after a I²C reading).
If the "stand-by out" and "diag. enable" commands are both given through a single programming step, the pulse
takes place first (power stage still in stand-by mode, low, outputs = high impedance).
Afterwards, when the Amplifier is biased, the PERMANENT diagnostic takes place. The previous Turn On state
is kept until a short appears at the outputs.
Figure 14. Turn - On diagnostic: working principle
Vs~5V
I (mA)
Isource
Isource
CH+
CH-
Isink
Isink
~100ms
Measure time
t (ms)
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