TDA7437N_03 查看數據表（PDF） - STMicroelectronics

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TDA7437N_03

DIGITALLY CONTROLLED AUDIO PROCESSOR

STMicroelectronics 

TDA7437N

vice doesn't recognize a START condition if a previously active communication was not ended by a STOP con-

dition.

I2C BUS READ MODE

The TDA7437N 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, followed by acknowledge bit.

The TDA7437N recognizes the request. At the following master generated clocks bits, the TDA7437N 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 TDA7437N.

- no acknowledge, stopping the read mode communication.

LOUDNESS STAGE

The previous SGS-THOMSON audioprocessors were implementing a fixed loudness response, only ON/OFF

sw programmable.

No possibility to change the loud boost rate at a certain volume level. The TDA7437N implements a fully pro-

grammable loudness control in 20 steps of 1dB.

It allows a customized loudness response for each application. The external network connected to the loudness

pins LOUD_L and LOUD_R fixes the type of loudness response

1)Simple CapacitorThe loudness effect is only a boost of low frequencies. (see Fig. 16)

2)Second order Loudness (boost of low and high frequencies).

3)Second order decreased type Loudness (lower boost of low and high frequencies).

4)Second order modified type Loudness (higher boost of low and high frequencies).

BASS & MID FILTERS

Several bass filter types can be implemented. Normally it is used the basic T-type Bandpass Filter.Starting from

the filter component values (R1 internal and R2, C1, C2 external), the centre frequency Fc, the gain Av at max

bass boost and the filter Q factor are computed as follows

Fc

=

--------------------------------1----------------------------------

2 ⋅ Π ⋅ R1 ⋅ R2 ⋅ C1 ⋅ C2

Av

=

R-----2-----⋅---C-----2-----+-----R----2-----⋅---C-----1-----+-----R-----1----⋅---C-----1--

R2 ⋅ C1 + R2 ⋅ C2

Q = -----(--R-----1-----⋅---R----2-----⋅---C-----1-----⋅---C-----2----)

R2 ⋅ C1 + R2 ⋅ C2

Viceversa fixed Fc, Av, and R1 (internal typ.±30%), the external component values are

C1 = ---------A-----v----–----1-----------

2 ⋅ Π ⋅ R1 ⋅ Q

C2 = -----Q------⋅---Q------⋅---C-----1-------

Av – 1 – Q ⋅ Q

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