TDA7340G datasheet(21/27 Pages) STMICROELECTRONICS

21 / 27 page

filter, the bass cut response becomes a low pass

filter, while the response in bass boost condition

is unchanged.

The feature is useful for human ear equalization

in noisy enviroments like cars etc.

See examples in Fig. 18 (symmetrical response)

and Fig. 19 (unsymmetrical response).

TRANSMITTED DATA (SEND MODE)

The TDA7340G allows the reading of four info

bits.

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 immedi-

ately, 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.

TDA7340G I

2C BUS PROTOCOL

The protocol is standard I

2C, using subaddress

byte plus data bytes (see pagg.11 to 16).

The optional Autoincrement mode allows to re-

fresh 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 subad-

dress 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 se-

quence.

Note:

that the autoincrement mode has a module 16

counter, whereas the total used register bytes are

10.

It is not correct to refresh all the 10 bytes starting

from a subaddress different than XX010000.

For example using subaddress XX010010 (vol-

ume) the registers

from Volume to Stereode-

coder (see pag.11) are correctly updated but the

next two transmitted bytes instead to refer to the

wanted Input selector and Loudness are dis-

charged. (the solution in this case is to send two

separated pattern in autoinc mode, the first com-

posed 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 necessity to resend each

time the address and subaddress bytes.

This feature can be implemented, for example, if

a gradual Volume change has to be performed (

the MCU has not to send the STOP condition,

keeping active the TDA7340G communication).

WARNING

The TDA7340G always needs to receive a STOP

condition, before beginning a new START condi-

tion. The device doesn’t recognize a START con-

dition if a previously active communication was

not ended by a STOP condition.

2C BUS READ MODE

The TDA7340G gives to the master a 1 byte

”TRANSMITTED INFO” via I2C bus in read

mode. The read mode is Master activated by

sending the chip address with LSB set to 1, fol-

lowed by acknowledge bit.

The TDA7340G recognizes the request. At the

following master generated clocks bits, the

TDA7340G

issues the TRANSMITTED INFO

byte on the SDA data bus line (MSB transmitted

first).

At the nineth clock bit the MCU master can:

- acknowledge the reception, starting in this

way the transmission of another byte from

the TDA7340G.

- no acknowledge, stopping the read mode

communication.

LOUDNESS STAGE

The previous STMicroelectronics audioprocessors

were implementing a fixed loudness response,

only ON/OFF sw programmable.

bit P= 0

Pause active

bit P= 1

No pause detected

bit ZM = 1

Zero cross mute ON

bit ZM = 0

Zero cross mute OFF

bit SM = 1

Soft mute ON

bit SM = 0

Soft mute OFF

bit ST = 1

Stereo signal detected (input MPX)

bit ST = 0

Mono signal detected (input MPX)

TDA7340G

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