TDA7564 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TDA7564 Datasheet PDF : 20 Pages
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TDA7564
current thresholds, as follows:
Iout > 500mApk = NORMAL STATUS
Iout < 250mApk = OPEN TWEETER
To correctly implement this feature, it is necessary to briefly provide a signal tone (with the amplifier in "play")
whose frequency and magnitude are such to determine an output current higher than 500mApk in normal con-
ditions and lower than 250mApk should the parallel tweeter be missing. The test has to last for a minimum num-
ber of 3 sine cycles starting from the activation of the AC diagnostic function IB2<D2>) up to the I2C reading of
the results (measuring period). To confirm presence of tweeter, it is necessary to find at least 3 current pulses
over 500mA over all the measuring period, else an "open tweeter" message will be issued.
The frequency / magnitude setting of the test tone depends on the impedance characteristics of each specific
speaker being used, with or without the tweeter connected (to be calculated case by case). High-frequency
tones (> 10 KHz) or even ultrasonic signals are recommended for their negligible acoustic impact and also to
maximize the impedance module's ratio between with tweeter-on and tweeter-off.
Fig. 21 shows the Load Impedance as a function of the peak output voltage and the relevant diagnostic fields.
This feature is disabled if any overloads leading to activation of the short-circuit protection occurs in the process.
Figure 21. Current detection: Load impedance magnitude |Z| vs. output peak voltage of the sinus
Load |z| (Ohm)
50
Low current detection area
30
(Open load)
20
D5 = 1 of the DBx byres
Iout (peak) <250mA
Iout (peak) >500mA
10
High current detection area
5
(Normal load)
D5 = 0 of the DBx bytes
3
2
1
1
2
3
4
5
6
7
8
Vout (Peak)
MULTIPLE FAULTS
When more misconnections are simultaneously in place at the audio outputs, it is guaranteed that at least one
of them is initially read out. The others are notified after successive cycles of I2C reading and faults removal,
provided that the diagnostic is enabled. This is true for both kinds of diagnostic (Turn on and Permanent).
The table below shows all the couples of double-fault possible. It should be taken into account that a short circuit
with the 4 ohm speaker unconnected is considered as double fault.
Double fault table for Turn On Diagnostic
S. GND (so)
S. GND (sk)
S. GND (so)
S. GND
S. GND
S. GND (sk)
/
S. GND
S. Vs
/
/
S. Across L.
/
/
Open L.
/
/
S. Vs
S. Vs + S. GND
S. Vs
S. Vs
/
/
S. Across L.
S. GND
S. GND
S. Vs
S. Across L.
/
Open L.
S. GND
Open L. (*)
S. Vs
N.A.
Open L. (*)
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