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TDA7575B

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
Software specifications TDA7575B
22/32 Doc ID 14103 Rev 3
6.1 Examples of bytes sequence
1 - Turn-on diagnostic - Write operation
L
2 - Turn-on diagnostic - Read operation
The delay from 1 to 2 can be selected by software, starting from T.B.D. ms
3a - Turn-on of the power amplifier with mute on, diagnostic defeat.
3b - Turn-off of the power amplifier
4 - Offset detection procedure enable
5 - Offset detection procedure stop and reading operation (the results are valid only for the
offset detection bits (D2 of the bytes DB1, DB2, DB3, DB4).
● The purpose of this test is to check if a D.C. offset (2 V typ.) is present on the outputs,
produced by input capacitor with anomalous leakage current or humidity between pins.
● The delay from 4 to 5 can be selected by software, starting from T.B.D. ms
Start Address byte with D0 = 0 ACK IB1 with D6 = 1 ACK IB2 ACK STOP
Start Address byte with D0 = 1 ACK DB1 ACK DB2 ACK STOP
Start Address byte with D0 = 0 ACK IB1 ACK IB2 ACK STOP
X000XXXX XXX1XX1X
Start Address byte with D0 = 0 ACK IB1 ACK IB2 ACK STOP
X0XXXXXX XXX0XXXX
Start Address byte with D0 = 0 ACK IB1 ACK IB2 ACK STOP
XX1XX1XX XXX1XXXX
Start Address byte with D0 = 1 ACK DB1 ACK DB2 ACK STOP
TDA7575B Diagnostics functional description
Doc ID 14103 Rev 3 23/32
7 Diagnostics functional description
7.1 Turn-on diagnostic
It is activated at the turn-on (stand-by out) under I
2
C bus 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 (Figure 29) is internally 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 I
2
C 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 29. Turn-on diagnostic: working principle
Fig. Figure 30 and Figure 31 show SVR and OUTPUT waveforms at the turn-on (stand-by
out) with and without Turn-on diagnostic.
Figure 30. SVR and output behavior - case 1: without turn-on diagnostic
CH-
CH+
Isource
Vs~5V
Isink
t (ms)
I (mA)
Isink
Isource
~100mS
Measure time
Bias (power amp turn-on)
t
Diagnostic Enable
(Permanent)
Permanent diagnostic
acquisition time (100mS Typ)
Permanent Diagnostics data (output)
permitted time
I2CB DATA
Vsvr
Out
FAULT
event
Read Data
Diagnostics functional description TDA7575B
24/32 Doc ID 14103 Rev 3
Figure 31. SVR and output pin behavior - case 2: with turn-on diagnostic
The information related to the outputs status is read and memorized at the end of the
current pulse top. The acquisition time is 100 ms (typ.). No audible noise is generated in the
process. As for short to GND / Vs the fault-detection thresholds remain unchanged from 26
dB to 12 dB gain setting. They are as follows:
Figure 32. Short circuit detection thresholds
Concerning short across the speaker / open speaker, the threshold varies from 26 dB to 12
dB gain setting, since different loads are expected (either normal speaker's impedance or
high impedance). The values in case of 26 dB gain are as follows:
Figure 33. Load detection thresholds - high gain setting
If the line-driver mode (Gv= 12 dB and line driver mode diagnostic = 1) is selected, the same
thresholds will change as follows:
Figure 34. Load detection thresholds - high gain setting
Bias (power amp turn-on)
permitted time
Turn-on diagnostic
acquisition time (100mS Typ)
t
Read Data
Permanent diagnostic
acquisition time (100mS Typ)
Permanent Diagnostics data (output)
permitted time
Diagnostic Enable
(Turn-on)
Turn-on Diagnostics data (output)
permitted time
I2CB DATA
Vsvr
Out
Diagnostic Enable
(Permanent)
FAULT
event
D02AU1341
S.C. to GND x S.C. to Vs
0V 1.8V V
S
-1.5V V
S
xNormal Operation
1.2V V
S
-0.9V
S.C. across Load x Open Load
0V 1.5Ω
70Ω
Infinite
xNormal Operation
0.5Ω
130Ω
D01AU1254
D01AU1252
S.C. across Load x Open Load
0Ω 4.5Ω 200Ω infinite
xNormal Operation
1.5Ω 400Ω
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32

TDA7575B

Mfr. #:
Buy TDA7575B
Manufacturer:
STMicroelectronics
Description:
Audio Amplifiers 2 x 75W Multifunct Dual-Bridge Pwr Amp
Lifecycle:
New from this manufacturer.
Delivery:
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