LA1837_09 Datasheet, PDF (5/9 Pages) Sanyo Semicon Device – For Home Stereo IC with Electronic Tuning Support Single-Chip IC

Continued from preceding page.
Pin No.
Pin function
11
FM-S-meter output
LA1837
Pin voltage (V)
0V
RL = 8kΩ
Pin description
12
AM S-meter output
AM SD sensitivity
adjustment
0V (AM)
The AM SD sensitivity is adjusted with the value of
the external resistor connected between this pin and
ground.
Equivalent circuit
11
12
28
13
AM and FM IF buffer
output,
output control switch
(mute switch)
0V
V13 ≤ 0.5 V : Reception state
1.4 V ≤ V13 ≤ 2.2 V : IF buffer output turned on
V13 ≥ 3.5 V : IF buffer output and muting are turned
on
14
Phase comparator
low-pass filter
VCC-1.4 (FM) Connecting this pin to ground through a resistor sets
0V (AM)
the IC to AM mode.
(FM/AM switching)
Resistor value limits :
2.7kΩ (when VCC = 7V)
3.9kΩ (8V) 5.1kΩ (9V)
6.2kΩ (10V) 7.5kΩ (11V)
15
Pilot detector
low-pass filter
(forced mono)
(VCO stop)
VCC-1.0
If a current of 50μA or greater flows from this pin, the
system is forced to mono.
Connecting this pin to ground stops the VCO.
The resistor limit values are the same as for pin 14.
16
Post amplifier input
17
and output
Vreg
Vreg
Output impedance ro = 200Ω
Pin 16 : right output, pin 17 : left output
18
Inverting inputs
18
19
Pin 18 : right input, pin 19 : left input
19
RNF = 33kΩ
20
MOX output
21
3.5V
3.5V
Output impedance ro = 3.3kΩ
Pin 20 : right de-emphasis
Pin 21 : left de-emphasis
22
MPX input
2.9V
Input impedance ri = 20kΩ
22
13
14
15
16
17
20
21
23
FM demodulator
output
24
AM detector output
25
AM AGC
2.8V (FM)
2.8V (AM)
0V (FM)
0.5V (AM)
0V (FM)
0.5V (AM)
Output impedance ro = 3.0kΩ
The separation can be modified by inserting a
capacitor between this pin and ground.
Set VO sub/VO main to be about 0 dB.
Output impedance ro = 3.3kΩ
The AM frequency characteristics can be modified
by adjusting the time constants of the circuits
between this pin and pin 22, and between this pin
and ground.
The built-in load resistor R = 11kΩ.
23
24
25
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No.5688-5/9