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Mode
AC Signal
Audio 1
External
Audio
Audio 2
External
Audio
Video 1
Video 2
NOTES: 1. Refer to Table 2 to determine the active demodulator (AM and or FM) and the associated audio output pins.
2. The Variable output audio level is controlled by Pin 1.
Television Standard
Modulation
Modulation
System
S
PAL 1
PAL 2
SECAM
NTSC
Multi–Standard Operating Modes
The MC44302A is designed to operate properly with PAL
(B, G, I,) SECAM (L), and NTSC (M) television transmission
standards. There are two multifunction inputs that are used
t o s e l e c t t h e p r o p e r c o n t r o l m e t h o d s f o r v i d e o
demodulation, sound intercarrier demodulation, and AGC.
This keeps the sense of the video signal at the outputs the
same, whether positive or negative modulation is being
received. Refer to Table 2 and the following operating
description.
The PAL, NTSC, and SECAM standard are each selected
by applying a specific dc voltage level to the Video Mode
Switch at Pin 10. With PAL 1 selected, AGC is keyed on the
sync pulse by the horizontal PLL which is locked to the
flyback or video sync pulse present at Pin 17. The FM sound
IF and detector is active with the demodulated audio
appearing at Pins 24 and 27. The PAL 2 selection is identical
to PAL 1 with the addition of sound muting when the
Acquisition Circuit is unlocked or vertical sync is absent. With
SECAM selected, the video level is established by both, a
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Table 1. Audio Input/Audio–Video Switch
Inputs
Inputs
to Pin 3
DC Level
(V
= 5.0 V)
CC
Open
or
3.4 V to 5.0 V
22 kΩ to Ground
or
1.8 V to 2.2 V
–
3.3 kΩ to Ground
or
0.6 V to 0.9 V
–
Grounded
or
0 V to 0.03 V
Table 2. Television Standard Modes
Mode Selection
Video
Pin 10
Voltage
Voltage
Polarity
(V)
Loading
Negative
4.0 to 5.0
Negative
3.2 to 4.0
Positive
1.9 to 3.0
Negative
Ground
MC44302A
1
Audio
Constant
Variable
Pin 24
Pin 27
Internal Audio
Internal Audio
(AM or FM)
(AM or FM)
Internal Audio
External Audio
(AM or FM)
Internal Audio
Internal Audio
(AM or FM)
(AM or FM)
Internal Audio
Internal Audio
(AM or FM)
(AM or FM)
AGC
Pin 16
Reference
DC
DC
and
and
Method
Open
Black Level
Sync Tip Keyed
Open
Black Level
Sync Tip Keyed
Open
Black Level
Back Porch Keyed
White Level
Peak Detected Video
Open
Black Level
Sync Tip Keyed
long time constant peak white detector, and a back porch
keyed AGC that corrects for transmitted black level errors
while maintaining fast AGC response. The AM sound
detector is active with the demodulated audio appearing at
Pins 24 and 27. With NTSC selected, AGC and sound muting
is the same as for PAL 1 mode. The FM and AM detectors are
both active with the FM output at Pin 27 and the AM output at
Pin 24. The AM output can be used to obtain the sync signal,
in suppressed sync scrambling systems, that is amplitude
modulated on the sound carrier.
Signal Acquisition and AFT
The automatic fine tuning (AFT) portion of this integrated
circuit is unconventional in form. AFT control is derived by
amplifying the phase detector error voltage and applying it to
the tuner local oscillator (LO) after phase lock is established.
This method eliminates the need for a discriminator coil along
with the associated alignment, and the potential for IF
instability due to coil radiation.
Outputs
Video
2
Negative
Pin 5
Negative Video
Negative Video
Negative Video
Positive Video
with
White Spot Inversion
IF and
Time
Modulation
Constant
Constant
Pin #
Active
Inhibited
14
FM
14
FM
14
AM
7
14
AM & FM
Positive
Pin 6
Positive Video
with
White Spot Inversion
Positive Video
with
White Spot Inversion
Positive Video
with
White Spot Inversion
Negative Video
Sound
Audio
Output
Output
Pin #
AM
24, FM
27, FM
AM
24, FM
27, FM
FM
24, AM
27, AM
–
24, AM
27, FM
13
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