TDA7407 STMicroelectronics, TDA7407 Datasheet - Page 28

• Manufacturer Part Number: TDA7407
• Description: IC PROCESSOR CAR SIGNAL 44TQFP
• Manufacturer: STMicroelectronics
• Type: Car Signal Processorr

Specifications of TDA7407

• Applications: Automotive Audio
• Mounting Type: Surface Mount
• Package / Case: 44-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3979

Multipath detector
5.2.4
5.2.5
5.2.6
28/46
De-emphasis and Highcut.
The lowpass filter for the de-emphasis allows to choose between a time constant of 50μs
and 75μs (bit D7, stereo decoder byte).
The highcut control range will be in both cases τ
range (between VHCH and VHCL) the LEVEL signal is converted into a 5 bit word which
controls the lowpass time constant between τ
remain always 5 bits independently of the absolute voltage range between the VHCH and
VHCL values.
The highcut function can be switched off by I
PLL and pilot tone detector
The PLL has the task to lock on the 19kHz pilotone during a stereo transmission to allow a
correct demodulation. The included detector enables the demodulation if the pilot tone
reaches the selected pilot tone threshold V
detector output (signal STEREO, see block diagram) can be checked by reading the status
byte of the TDA7407 via I
Field strength control
The fieldstrength input is used to control the high cut and the stereoblend function. In
addition the signal can be also used to control the noiseblanker thresholds and as input for
the multipath detector.
Figure 21. Relation between internal and external LEVEL voltage and setup of
Figure 22. High cut characteristics
VOLTAGES
INTERNAL
REF 5V
VSBL
stereoblend
VMO
SETUP OF VST
TIME CONSTANT
LOWPASS
VST
3
τ
•
2
Deemp
τ
C bus.
Deemp
LEVEL
FIELDSTRENGHT VOLTAGE
t
LEVEL INTERN
VHCL
PTHST
D97AU640
2
VSBL
Deemp
C bus (bit D7, fieldstrength byte set to "0").
VOLTAGES
INTERNAL
. Two different thresholds are available. The
REF 5V
HC
58%
50%
42%
33%
D97AU639
...3 · τ
= 2 · τ
VHCH
Deemp
Deemp
FIELDSTRENGHT
SETUP OF VMO
VMO
. There by the resolution will
. Inside the highcut control
VST
LEVEL INTERN
FIELDSTRENGHT VOLTAGE
t
TDA7407