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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ICs for FM/AM Tuner
AN7259S
• Detection Block
Pin11 and Pin12 constitutes a phase-shifting circuit of the QUAD detector
by external circuit.The R7 is a coil damp resistor, and it exerts influences on
the noise, THD, and output level.
Its recommended value is 1.2kΩ ~ 1.8kΩ.
Pin9 is the AFC voltage output pin,and according to the value of R10, the
band width of the Pin4 search output can be adjusted.
Pin13 is the center frequency adjusting pin of the Pin4 search output, and
makes it possible to adjust the center frequency of the search output
independently of the coil.
R10
R9
VCC
43kΩ
VCC
9 10
C7 0.2µA C8
VCC
11 12 13 14
C9
15pF VR
R7
1.2
R8 200kΩ
820Ω
kΩ
R10
30kΩ
VREF
C11
*An Example of Coil Adjusting Method
In case of channel selection by IF counter output
Adjust the coil so that the V (9, 14) at Vin= 0dBµbecomes
equal to V (9, 14) at Vin= 100dBµ.
In case of channel selection by search output
Same as above. Thereafter,adjust the center frequency of
the search output by the Pin13 VR.
V (9, 14) ··· DC voltage between Pin9 and Pin14
Vin ··· Level of IF input Pin20
• Reference Voltage (VREF)
The reference voltage (3.9V) is output from Pin14. Remember to bypass
it by an external capacitor since this line is used as the power supply line to
the limiter.
• IF Counter Output SSC
Pin16 is the IF counter output pin, and the output of about 300mVP– P is
obtainable on this pin. Because of its high gain, the IF counter output line is
separated on the pattern from the Pin20 (IF input) line in order to avoid
oscillation trouble.
Pin15 is the SSC pin to stop the IF counter, and according to the
VSSC level, the IF counter operation changes as shown in the table be-
low. The H level must be 4.2V or higher, and the L level must be 1V
or lower. SSC is used for prevention of the bad influences of the IF
counter output on the other blocks in the receiving mode.
VSSC
H
IF counter
ON
L
STOP
VREF
Limiter
8
14
19
VREF
20kΩ
15
200kΩ R2
200kΩ R3
16
C3
200pF
IF counter output
SSC IN (from microcomputer)
• IF Input Block
Pin20 is the IF input pin, and the input impedance is set between this pin
and Pin17 by R1. Usually a resistor of 330Ω is used as R1 to secure
optimum matching with CF.
Pin17 and Pin18 are the internal DC feedback pins, and the high
frequency components are bypassed through C1 and C2.
Pin19 is the GND pin dedicated to the limiter, and each GND of CF, C2 and C1
must be set close to Pin19. Externally short the GND of Pin19 with the GND
of Pin8.
30kΩ 30kΩ
17 18 19 20
CF
R1
IF in
C2
C1
330Ω
0.022µF 0.022µF
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