E-TDA7476013TR Datasheet E-TDA7476, TDA7476, TDA7476013TR | P10-P12

TDA7476

10/19

■ The minimum voltage of the AUX IN pins to sense the open load condition is 2V.

■ The minimum voltage of the AUX IN pin to detect the short circuit to GND by sensing drop on the resistor

is 4.5V. If this voltage is below 2V, the AUX line is considered short circuited to GND. From 2V to 4.5V

the sensing circuit can detect a short circuit in both ways (by sensing across the resistor or through the

voltage between the AUX IN pin and GND).

C BUS INTERFACE

Data transmission from microprocessor to the TDA7476 and viceversa takes place through the 2 wires I

C BUS

interface, consisting of the two lines SDA and SCL (pull-up resistors to positive supply voltage must be connected).

Data Validity

As shown by fig. 2, the data on the SDA line must be stable during the high period of the clock. The HIGH and

LOW state of the data line can only change when the clock signal on the SCL line is LOW.

Start and Stop Conditions

As shown by fig. 3 a start condition is a HIGH to LOW transition of the SDA line while SCL is HIGH. The stop

condition is a LOW to HIGH transition of the SDA line while SCL is HIGH.

Byte Format

Every byte transferred to the SDA line must contain 8 bits. Each byte must be followed by an acknowledge bit.

The MSB is transferred first.

Acknowledge

The transmitter* puts a resistive HIGH level on the SDA line during the acknowledge clock pulse (see fig.4). The

receiver** the acknowledges has to pull-down (LOW) the SDA line during the acknowledge clock pulse, so that

the SDAline is stable LOW during this clock pulse.

* Transmitter

= master (

P) when it writes an address to the TDA7476

= slave (TDA7476) when the

P reads a data byte from TDA7476

** Receiver

= slave (TDA7476) when the

P writes an address to the TDA7476

= master (

P) when it reads a data byte from TDA7476

Figure 2. Data Validity on the I

CBUS

SDA

SCL

DATA LINE

STABLE, DATA

VALID

CHANGE

DATA

ALLOWED

D99AU1031

11/19

TDA7476

Figure 3. Timing Diagram on the I

CBUS

Figure 4. Acknowledge on the I

CBUS

SOFTWARE SPECIFICATIONS

The TDA7476 is activated by turning-on the ST-BY pin (CMOS compatible). In this condition it waits for the

I2CBus addressing byte

ADD1

(WRITE to TDA7476)

This sequence (where the bit 0 of ADD1 is at 0 level) enables the acquisition routine and starts the single pulse

(containing infrasonic harmonics) for the test. During this period the data regarding all the outputs are memo-

rized.After a period Twait1 that depends on the value of the timing capacitor (see

Timing

) the

P redirects the

TDA7476 by the byte

ADD2

The byte ADD2 contains the bit 0 at 1 level. This enables the reading mode, TDA7476's. The 3 bytes with the

diagnostic information

BYTE1, BYTE2, BYTE3

(READ FROM TDA7476) are now transmitted to the

The address of TDA7476 is selected using pin ADD (pin 4) .

If ADD is connected to ground, then A = 0 and the TDA7476 address is 0100010X.

If ADD is connected to 5V, than A = 1 and the TDA7476 address is 0100011X

■ The TDA7476 provides two types of diagnostic information:

A) TURN-ON DIAGNOSTIC

- The first time that the TDA7476 is addressed by I

CBus, the more complete set

of diagnostic information is activated:

- CH1, CH2, CH3, CH4, CH5

Short Circuit to GND

Short Circuit to Vs

Open Load (*)

Short Circuit across the load (*)

(*) Detected if the power amplifiers are in ST-BY condition.

- AUX1, AUX2

Short Circuit to GND (*)

Open Load (*)

(*) Detected if the high side drivers attached to the Aux outputs are ON.

Here following the turn-on diagnostic output bytes

ADD1

S 010001A 0 ACK STOP

ADD1

S 010001A 0 ACK BYTE1 ACK BYTE2 ACK BYTE3 ACK STOP

SCL

SDA

START

CBUS

STOP

D99AU1032

SCL

MSB

23789

SDA

START

ACKNOWLEDGMENT

FROM RECEIVER

D99AU1033

TDA7476

12/19

READ BYTE 1

READ BYTE 2

READ BYTE 3

When the

P reads correctly all the 3 bytes containing the mentioned information and gives the last acknowl-

edge, the TDA7476 switches to the "permanent diagnostic operation"

B) PERMANENT DIAGNOSTIC

It can sense the following diagnostic information:

CH1, CH2, CH3, CH4, CH5

- Short Circuit to GND

- Short Circuit to Vs

Aux1, Aux2

- Short Circuit to GND (*)

- Open Load (*)

(*) Detected if the high side drivers attached to the Aux outputs are ON.

In this case the above conditions are not detected while the single infrasonic current pulse is present but be-

fore. The fault condition must be present for more than 2sec. (typ) and must be also true during the pulse,

where the data are memorized and then transmitted.The bytes from/to

P and TDA7476 are the same as

those in case of turn-on diagnostic (see above).

Here following is the permanent diagnostic output Data Bytes. The bits D7 and D6 of the first byte both stand at

0 level. This condition, although not possible during the turn-on diagnostic, can be useful to confirm that the

bytes are referred to the permanent diagnostic.

MSB LSB

STATUS

D7 D6 D5 D4 D3 D2 D1 D0

X X X X 1 1 X 0 CH1 short circuit to Vs

X X X X 1 1 0 X CH1 short circuit to GND

X X X X 1 0 1 1 CH1 open load

X X X X 0 1 1 1 CH1 short circuit across the load

1 1 X 0 X X X X CH2 short circuit to Vs

1 1 0 X X X X X CH2 short circuit to GND

1 0 1 1 X X X X CH2 open load

0 1 1 1 X X X X CH2 short circuit across the load

X X X X 1 1 X 0 CH3 short circuit to Vs

X X X X 1 1 0 X CH3 short circuit to GND

X X X X 1 0 1 1 CH3 open load

X X X X 0 1 1 1 CH3 short circuit across the load

1 1 X 0 X X X X CH4 short circuit to Vs

1 1 0 X X X X X CH4 short circuit to GND

1 0 1 1 X X X X CH4 open load

0 1 1 1 X X X X CH4 short circuit across the load

X X X X X X 1 0 AUX1 short circuit to GND

X X X X X X 0 1 AUX1 open load

X X X X 1 0 X X AUX2 short circuit to GND

X X X X 0 1 X X AUX2 open load

1 1 X 0 X X X X CH5 short circuit to Vs

1 1 0 X X X X X CH5 short circuit to GND

1 0 1 1 X X X X CH5 open load

0 1 1 1 X X X X CH5 short circuit across the load

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P19

E-TDA7476013TR

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Audio DSPs CAR RADIO DIAG PROCESSOR

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E-TDA7476013TR

E-TDA7476013TR

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