tda4474-msd ATMEL Corporation, tda4474-msd Datasheet - Page 5

• Manufacturer Part Number: tda4474-msd
• Description: Multistandard Video-if And Quasi Parallel Sound Processing
• Manufacturer: ATMEL Corporation

Rev. A2, 04-Dec-98
AM Demodulator
The alignment-free AM demodulator is realized by a
synchronous detector. The modulated SIF signal from the
SIF amplifier output is multiplied in phase with the
limited SIF signal (AM is removed). The AF signal of the
demodulator output is fed to the output amplifier and to
the SIF-AGC. For all TV standards with negative video
modulation (e.g., B/G standard) the AF output signal
(Pin 27) is switched off by the standard switch.
Quasi-Parallel-Sound (QPS) Mixer
The QPS mixer is realized by a multiplier. The SIF signal
(FM or NICAM carrier) is converted to the intercarrier
frequency by the regenerated picture carrier (quadrature
signal) which is provided from the VCO. The intercarrier
signal is fed via an output amplifier to Pin 26.
Standard Switch
To have equal polarity of the video output signal the
polarity can be switched in the demodulation stage in
accordance with the TV standard. Additional a standard
dependent dc level shift in the video amplifier delievers
the same sync. level. Parallel the correct VIF-AGC is
selected for positive or negative modulated VIF signals.
In case of negative modulation (e.g., B/G standard) the
AM output signal is switched off. If the standard for
positive modulation (L standard) is selected the AM
demodulator and QPS mixer is active. This condition
allows a parallel operation of the AM sound signal and the
NICAM-L stereo sound.
Absolute Maximum Ratings
Reference point Pin 4 (9, 18), unless otherwise specified
*) Equivalent to discharging a 200 pF capacitor through a 0
Supply voltage
Supply current
Power dissipation, V
Output currents
External voltages
Junction temperature
Storage temperature
Electrostatic handling *)
Pins 1, 2, 5–8, 10–12, 14, 16, 19, 20, 26–30
s
= + 9 V
Parameters
Pin 25
Pin 25
Pin 14, 26, 27
Pins 17, 22, 23
Pin 13
Pins 3, 15, 21, 24
all pins
W
L’ Switch and VIF Input Selection
For positive modulated signals (L/L’ standard) Pin 16
works as L’ switch. With a control voltage the VCO
frequency can be switched for setting to the required
L’ value (L’ standard). Also a fine adjustment of the
L’-VCO center frequency is possible by a potentiometer.
The L’ switch is only active for positive modulated video
IF signals (standard switch in L mode). In this mode the
video IF input 2 (VIF2) is forced by the standard switch.
The possibility to select VIF1 input is given by
connecting VIF2 input (Pin 10 or 11) via 10 k
to ground.
If negative modulation (B/G mode) is selected Pin 16
operates as an input selection switch for the two VIF
inputs.
AFC Switch
The AFC output signal at Pin 24 can be controlled by a
switching voltage at Pin 21. It is possible to select an AFC
output signal with rising- or falling AFC curve and to
switch off the AFC.
Internal Voltage Stabilizer
The internal bandgap reference ensures constant
performance independant of supply voltage and
temperature.
resistor
Symbol
V
V
T
I
V
T
ESD
I
out
P
ext
stg
s
s
j
–25 to +125
+ 13.5
"
Value
+ 4.5
+ 3.5
+125
840
9.0
93
V
5
300
s
TDA4474
W
Unit
mW
mA
mA
V
V
V
V
V
V
C
C
resistor
5 (16)