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Pin No.
22
23
24
25
26
Sound Quadrature Coil (FM)
MOTOROLA ANALOG IC DEVICE DATA
Downloaded from
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PIN FUNCTION DESCRIPTION (continued)
Equivalent Internal Circuit
22
Gnd
From Ceramic Sound
IF Filter at Pin 28
Sound Input (AM)
23
V CC
V CC
5.5 k
V CC
200
V CC
Audio Output
(Constant)
24
1.0 mA
5.0 V
330
0.01
V CC
25
V CC
C25
R28
L3
26
V CC
V CC
V CC
Reactance Stage
Representation
MC44302A
Gnd
This pin is the internal circuit ground. Care must be taken with the
printed circuit board layout to provide a continuous sea of copper
around the IC.
Sound Input (AM)
This pin is the input of the AM IF. The intercarrier sound output at
Pin 28 connects to this input through a ceramic bandpass filter.
The AM detector is active in SECAM and NTSC modes. Refer to
Table 2.
Audio Output (Constant)
This is the constant audio output. The audio source is controlled
by the mode selection of Pin 3. Refer to the description of Pin 3,
and to Tables 1 and 2.
V CC
This pin is the positive supply of the video/sound IF IC. The IC is
functional over a minimum range of 4.75 V to 5.5 V and requires
100 mA. Operation from higher input voltages is possible with a
preregulator. For optimum performance, it is recommended that
circuit board layout contains dual power supply bypass capacitors
with short leads connected directly to the V CC pin and ground.
Sound Quadrature Coil (FM)
The sound quadrature tank components connect from this pin to
V CC . The internal circuitry is designed to eliminate the time
consuming alignment procedure by self tuning to the sound
intercarrier frequency. This allows the use of economical fixed
value components for a specific frequency or for a range of
frequencies. The internal tuning capacitance that is placed across
the tank ranges from 0.25 pF to 19 pF. Refer to Figures 9, 10, and
Table 3 to select the proper component values for C25, R28, and L3.
Description
23
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