LA1837M Просмотр технического описания (PDF) - ON Semiconductor
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LA1837M Datasheet PDF : 9 Pages
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Continued from preceding page.
Pin No.
Pin
10
AM narrow band
ceramic filter
connection
Pin
voltage
1.3V
11
FM S-meter
0V
output
LA1837M
Equivalent circuit
Pin function
Recommended narrow band ceramic filter
BFU450C4N (Murata Mfg. Co., Ltd.)
When the narrow band SD function is not used, bypass this circuit
by connecting a 50Ω resistor and a 0.047µF capacitor in series.
RL = 8kΩ
12
AM S-meter
0V (AM)
output,
AM SD
sensitivity
adjustment
13
AM/FM IF buffer 0V
output,
Output control
switch (muting
switch)
14
Phase
comparator
VCC-1.4
(FM)
low-pass filter 0V (AM)
(FM/AM
switching)
15
Pilot detector
VCC-1.0
low-pass filter
(Forced
monaural)
(VCO stop)
16
Post amplifier
Verg
17
I/O
Verg
18
19
20
Multiplex output 3.5V
21
3.5V
22
Multiplex input 2.9V
The AM SD sensitivity can be adjusted with an external resistor
between this pin and ground.
V13 ≤ 0.5V: Reception state
1.4V ≤ V13 ≤ 2.2V: IF buffer output on
V13 ≥ 3.5V: IF buffer output and muting on
The IC switches to AM mode when this pin is connected to ground
through a resistor.
Resistor value limits: 2.7kΩ (when VCC = 7V)
3.9kΩ (8V) 5.1kΩ (9V)
6.2kΩ (10V) 7.5kΩ (11V)
When a current of over 50µA is sourced by this pin, the IC
switches to forced monaural mode.
The VCO is stopped if this pin is connected to ground.
The resistor value limits are the same as for pin 14.
Output impedance ro = 200Ω
Pin 16: right output, pin 17: left output
Inverting input pins
Pin 18: right input, pin 19: left input
RNF = 33kΩ
Output impedance ro = 3.3kΩ
Pin 20: Right channel deemphasis
Pin 21: Left channel deemphasis
Input impedance ri = 20kΩ
23
FM
2.8V (FM)
demodulated
2.8V (AM)
output
Output impedance ro = 3.0kΩ
The separation can be adjusted with an external capacitor
connected between this pin and ground.
The VOsub/VOmain ratio is set to be approximately 0dB.
Continued on next page.
No.8271-5/9
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