LA1787M Datasheet, PDF (17/54 Pages) Sanyo Semicon Device – Single-Chip Tuner IC for Car Radios

Continued from preceding page.
Pin No.
Function
53
IF amplifier output
56
IF amplifier input
54
Mixer output: 130 µA
49
Mixer input
LA1787M
Description
• Input and output pin or the first
IF amplifier
• Inverting amplifier
V56 = 2 V
Input impedance: R_IN = 330 Ω
V53 = 5.3 V
Output impedance
R_OUT = 330 Ω
IF OUT 53
Equivalent circuit
VCC
2.75V
300Ω
IF IN 56
The mixer coil connected to the
pin 54 mixer output must be
wired to V_CC (pin 40).
The pin 49 mixer input
impedance is 330 Ω
Pin 40 VCC
Pin 40 VCC
54
49
330Ω
300Ω
A13590
OSC
55
W-AGC IN
AM SD ADJ
58
N-AGC IN
Muting attenuation
adjustment pin
Pins 55 and 58 include built-in
DC cut capacitors.
The AGC on level is determined
by the values of the capacitors
C1 and C2.
Pin 55 functions as the SD
sensitivity adjustment pin in
AM mode.
The output current I55 is 50 µA,
and V55 varies depending on the
value of the external resistor.
The SD function operates by
comparing V55 with the S-meter
voltage.
62 pin
VCC
W-AGC
A13591
N-AGC
55
C1
30pF
50pF
MIX ₅₈
IN
C2
MIX
OUT
50µA
AM SD
Signal meter
A13592
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