AN7259 データシートの表示（PDF） - Panasonic Corporation
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AN7259 Datasheet PDF : 5 Pages
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AN7259S
ICs for FM/AM Tuner
s Application Circuit
FROM
F.E.
330Ω
IF COUNTER
OUT
SSC REF
200kΩ
+
200kΩ
820Ω
15pF
1.2kΩ
20
19
18
17
16
15
14
13
12
11
AN7259S
1
2
3
4
5
6
7
8
9
10
+
10kB
100kΩ
+
30kB
0.22µF
VCONT.
OUT
SEARCH
7.5kΩ
+
AF OUT
1000pF
VCC
0.022µF
s Pin Descriptions
• Control Signal Output Block
The AN7259S has linear level meter output (control voltage on Pin2)
whose dynamic range is about 60dB wider for change of the input. This
control voltage is adjustable by the resistor R4 of Pin1. The adjustable range
at R4= 0.8kΩ ~ 10kΩ is more than 30dB in conversion of the input.
The polarity of the output voltage from Pin3 is reverse to that of the voltage
to be output from Pin2. This output from Pin3 requires insertion of a
capacitor (C5 = 4.7µF) since it is used for soft muting. The search output
(right sketch) to be used for channel selection is obtainable on Pin4. The
band width of this search output is adjustable. (Refer to Detection Block.)
The search stop sensitivity is externally adjustable because the L level
value varies with the input signal level.
• Soft Mute
Pin7 is the AF output pin, and the emitter follower output of≈300Ω in
output impedance is obtainable on this pin.
Pin6 is the soft mute adjusting pin to adjust the attenuation at the non-input
mode.
Soft mute here denotes muting by the level signal output from Pin3, and
the soft mute response varies with the time constant of this voltage output.
The r2 and C12 are related to the weak input S/N and the soft mute ON time,
and with increase of the C12 value, the weak input S/N is proportionately
improved, but the speed of response accordingly becomes lower. The r1, on
the other hand, is related to the soft mute OFF time. Each value specified in
the right sketch denotes a recommended value.
200Ω 200Ω
10kΩ
1
R4
10kB
~ 20kB
23
R5
C4
C5
0.022µF
4.7 1.8
µF kΩ
4
Search output
C6
0.22 20kΩ
µF R6
Control voltage output
Control voltage
Search output
Increase of R4
30dB
Input
Frequency
VCC
200Ω
2kΩ r2 36kΩ
r1
3
5
+ C12
4.7µF
GND
67 8
VREF
VR
AF
R13 OUT
To VCC
C13
Soft mute
adj.
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