TDA7437N datasheet(25/34 Pages) STMICROELECTRONICS

25 / 34 page

TDA7437N

Mute and pause features

25/34

The type (stereo/mono) of received broadcasting signal is easily checked and displayed by

using the ST bit.

The P bit check is useful in tuning jumps without signal muting.

The SM soft mute status becomes active immediately, when bit D0 is set to 1 (soft mute ON,

MUTE byte) and not when the signal level has reached the 60 dB final attenuation.

5.8

TDA7437N I2C bus protocol

The protocol is standard I2C, using subaddress byte plus data bytes (as shown within

Chapter 4).

The optional autoincrement mode allows to refresh all the bytes registers with transmission

of a single subaddress, reducing drastically the total transmission time.

Without autoincrement, subaddress bit I = 0, to refresh all the bytes registers (10), it is

necessary to transmit 10 times the chip address, the subaddress and the data byte.

Working with a 100Kb/s clock speed the total time would be :

[(9*3+2)*10]bits*10us=2.9ms

Instead using autoincrement mode, subaddress bit I=1, the total time will be:

(9*12+2)*10us=1.1ms.

The autoincrement mode is useful also to refresh partially the data. For example to refresh

the 4 speakers attenuators it is possible to program the subaddress Spkr LF (code

XX010100), followed by the data byte of SPKR LF, LR, RF, RR in sequence.

Note: that the autoincrement mode has a module 16 counter, whereas the total used

It is not correct to refresh all the 10 bytes starting from a subaddress different than

XX010000.

For example; using subaddress XX010010 (volume), the registers from Volume to Mute (see

Table 5) are correctly updated, but the next two transmitted bytes, refer instead to the

wanted Input selector, and Loudness are discharged. (the solution in this case is to send

two separate patterns in autoincrement mode, the first composed by address, subaddress

XX010010, 8 data bytes, and the second composed by address, subaddress XX010000, 2

data bytes).

With autoincrement disabled, the protocol allows the transmission in sequence of N data

bytes of a specific register, without the necessity to resend the address and subaddress

bytes, each time.

This feature can be implemented, for example, if a gradual volume change has to be

performed (the MCU does not send the STOP condition, but keeps the TDA7437N

communication active).

Warning:

The TDA7437N always needs to receive a STOP condition,

before beginning a new START condition. The device doesn't

recognize a START condition if a previously active

communication was not ended by a STOP condition.

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