OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

TDA7567PDTR

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30
TDA7567PD Diagnostics functional description
Doc ID 16903 Rev 2 13/30
Figure 7. 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 16 dB gain setting. They are as follows:
Figure 8. Short circuit detection thresholds
Concerning short across the speaker / open speaker, the threshold varies from 26 dB to
16 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 9. Load detection thresholds - high gain setting 26 dB
If the line driver mode (G
v
= 16 dB and line driver mode diagnostic = 1) is selected, the
same thresholds will change as follows:
Figure 10. Load detection thresholds - low gain setting 16 dB
D01AU1253
S.C. to GND x S.C. to Vs
0V 1.8V V
S
-1.8V V
S
xNormal Operation
1.2V V
S
-1.2V
S.C. across Load x Open Load
0V 1.5Ω
45Ω
Infinite
xNormal Operation
0.5Ω
85Ω
AC00060
S.C. across Load x Open Load
0Ω 7Ω 180Ω infinite
xNormal Operation
1.5Ω 330Ω
Diagnostics functional description TDA7567PD
14/30 Doc ID 16903 Rev 2
3.2 Permanent diagnostics
Detectable conventional faults are:
– Short to GND
–Short to Vs
– Short across the speaker
The following additional features are provided:
– Output offset detection
The TDA7567PD has 2 operating status:
1. RESTART mode. The diagnostic is not enabled. Each audio channel operates
independently from each other. If any of the a.m. faults occurs, only the channel(s)
interested is shut down. A check of the output status is made every 1 ms (Figure 11).
Restart takes place when the overload is removed.
2. DIAGNOSTIC mode. It is enabled via I
2
C bus and self activates if an output overload
(such to cause the intervention of the short-circuit protection) occurs to the speakers
outputs. Once activated, the diagnostics procedure develops as follows (Figure 12):
– To avoid momentary re-circulation spikes from giving erroneous diagnostics, a
check of the output status is made after 1ms: if normal situation (no overloads) is
detected, the diagnostic is not performed and the channel returns back active.
– Instead, if an overload is detected during the check after 1 ms, then a diagnostic
cycle having a duration of about 100 ms is started.
– After a diagnostic cycle, the audio channel interested by the fault is switched to
RESTART mode. The relevant data are stored inside the device and can be read
by the microprocessor. When one cycle has terminated, the next one is activated
by an I
2
C reading. This is to ensure continuous diagnostics throughout the car-
radio operating time.
– To check the status of the device a sampling system is needed. The timing is
chosen at microprocessor level (over half a second is recommended).
Figure 11. Restart timing without diagnostic enable (permanent) - Each 1ms time, a
sampling of the fault is done
Figure 12. Restart timing with diagnostic enable (permanent)
t
1-2mS
1mS 1mS 1mS
1mS
Overcurrent and short
circuit protection intervention
(i.e. short circuit to GND)
Short circuit removed
Out
t
Overcurrent and short
circuit protection intervention
(i.e. short circuit to GND)
Short circuit removed
1-2mS 100/200mS 1mS1mS
TDA7567PD Diagnostics functional description
Doc ID 16903 Rev 2 15/30
3.3 Output DC offset detection
Any DC output offset exceeding ±2 V are signalled out. This inconvenient might occur as a
consequence of initially defective or aged and worn-out input capacitors feeding a DC
component to the inputs, so putting the speakers at risk of overheating.
This diagnostic has to be performed with low-level output AC signal (or V
in
= 0).
The test is run with selectable time duration by microprocessor (from a "start" to a "stop"
command):
– START = Last reading operation or setting IB1 - D5 - (OFFSET enable) to 1
– STOP = Actual reading operation
Excess offset is signalled out if persistent throughout the assigned testing time. This feature
is disabled if any overloads leading to activation of the short-circuit protection occurs in the
process.
3.4 AC diagnostic
It is targeted at detecting accidental disconnection of tweeters in 2-way speaker and, more
in general, presence of capacitively (AC) coupled loads.
This diagnostic is based on the notion that the overall speaker's impedance (woofer +
parallel tweeter) will tend to increase towards high frequencies if the tweeter gets
disconnected, because the remaining speaker (woofer) would be out of its operating range
(high impedance). The diagnostic decision is made according to peak output current
thresholds, and it is enabled by setting (IB2-D2) = 1.
Two different detection levels are available:
● High current threshold IB2 (D7) = 0
– Iout > 500 mApk = NORMAL STATUS
– Iout < 300 mApk = OPEN TWEETER
● Low current threshold IB2 (D7) = 1
– Iout > 250 mApk = NORMAL STATUS
– Iout < 125 mApk = 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 500 mApk with IB2(D7)=0 (higher than 250 mApk with IB2(D7)=1) in normal
conditions and lower than 250 mApk with IB2(D7)=0 (lower than 125 mApk with IB2(D7)=1)
should the parallel tweeter be missing.
The test has to last for a minimum number of 3 sine cycles starting from the activation of the
AC diagnostic function IB2<D2>) up to the I
2
C reading of the results (measuring period). To
confirm presence of tweeter, it is necessary to find at least 3 current pulses over the above
thresholds 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.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30

TDA7567PDTR

Mfr. #:
Buy TDA7567PDTR
Manufacturer:
STMicroelectronics
Description:
Audio Amplifiers 4 x 50W Multi Quad Built-in Diagnostic
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet