TDA7437 STMicroelectronics, TDA7437 Datasheet - Page 16

• Manufacturer Part Number: TDA7437
• Manufacturer: STMicroelectronics

Specifications of TDA7437

• Lead Free Status / Rohs Status: Not Compliant

TDA7437
WARNING
The TDA7437 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.
I
The TDA7437 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 TDA7437 recognizes the request. At the fol-
lowing
TDA7437 issues the TRANSMITTED INFO byte
on the SDA data bus line (MSB transmitted first).
At the nineth clock bit the MCU master can:
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 TDA7437 implements a fully programmable
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 loud-
ness response
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 in-
ternal and R2, C1, C2 external), the centre fre-
quency Fc, the gain Av at max bass boost and
the filter Q factor are computed as follows:
16/23
2
C BUS READ MODE
1) Simple Capacitor
2)Second order Loudness (boost of low and
3)Second order decreased type Loudness
4)Second order modified type Loudness (higher
The loudness effect is only a boost of low fre-
quencies. (see Fig.20)
high frequencies).
(lower boost of low and high frequencies).
boost of low and high frequencies).
- acknowledge the reception, starting in this
- no acknowledge, stopping the read mode
way the transmission of another byte from
the TDA7437.
communication.
master
generated
clocks
bits,
the
Viceversa fixed Fc, Av, and R1 (internal typ.+/-
30%), the external component values are:
TREBLE STAGE
The Treble stage is a simple high pass filter which
time constant is fixed by internal resistor (50Kohm
typ) and an external capacitor connected between
pins TREB_R/TREB_L and Ground.
IN-OUT PINS
The multiplexer output is available at OUT_R and
OUT_L pins for optional connection of external
graphic equalizer (TDA7316/TDA7317), surround
chip (TDA7346) etc. The signal is fed in again at
pins IN_L and IN-R. In case of application without
external devices the pins OUT_L/OUT_R and
IN_L/IN_R can be left unconnected if bit D3 byte
input selector is forced = 0 (DC connect) instead if
bit D3 is kept = 1 an external decoupling capacitor
must be provided between OUTR/INR and
OUTL/INR necessary to avoid signal DC jumps,
generating "Clicking" output noise.
The input impedance of the next volume stage is
44Kohm typical (minimum 31Kohm). A capacitor
no lower than 1 F should be used.
INPUT SELECTOR
The multiplexer selector can choose one of the
following inputs:
- a differential CD stereo input.
- a mono input.
- four stereo input
The signal fed to the input pins must be decou-
pled via series capacitors. The minimum allowed
value depends on the correspondent input imped-
ance. For the CD diff input (Zi=10Kohm worst
case ) a Cin=4.7uF is recommended.
R2
F
A
c
v
Q
2
R2 C2
2
C2
C1
R2 C1
R2 C1
R1 R2 C1 C2
A
A
C1 F
2
v
v
Q Q C1
R1 R2 C1 C2
R2 C1
A
1
1
1
v
c
R2 C2
R1 Q
R2 C2
Q Q
Q Q
1
A
v
R1 C1
1
Q