LA1781M_09 Datasheet, PDF (5/48 Pages) Sanyo Semicon Device – For Car Radios Single-Chip Tuner IC

LA1781M
Operating Characteristics and Symbols Used in the Test Circuit Diagrams
(1) Switches (SW)
Switch on = 1, SW off = 0
There are two switches that use signal transfer.
1) SW2 : switches between the mixer input and the IF input.
2) SW4 : switches between noise canceler input and IF output + noise canceler input.
(2) Types of SG used
PG1 (AC1) Used for noise canceler testing. A pulse generator and an AF oscillator are required.
AC2
Used for FM front end testing. Outputs an 83MHz signal.
AC3
Used for FM IF, noise canceler, and MPX testing. Outputs a 10.7MHz signal. Stereo modulation must be possible.
AC4
Used for AM testing. Outputs 1 MHz and 1.4MHz signals.
AC5
Used with the MRC. Can also be used for AF and OSC.
(3) Power supply
VCC
VCC1
VCC2
VCC3
8V
5V
0.1V/0.7V/2V/4V
0.1V/0.6V/2V
These levels must be
variable.
SD, stereo, seek/stop
Keyed AGC, Mute ATT
HCC, SNC, SASC (MRC)
(4) (a) Switches
Parameter
ON
OFF
SW1
SW2
AM/FM switching. The FE VCC is supplied to pin 62.
FM IF switching. Pin 51/FE output
FM
FE IF OUT (A)
AM
AC3 (B)
SW3 For conversion gain testing
Conversion gain measurement (A)
Other/purposes
SW4
SW5
For switching between noise canceler input and IF output + noise
canceler.
High-speed SD
AC1 (A)
High-speed SD
Other/purposes
Other/purposes
SW6 SEEK/STOP (IF BUFF ON/OFF)
STOP
Seek (IF buffer output)
SW7 MUTE ATT 200kΩ
MUTE 200kΩ
OFF
SW8 MUTE ATT 30kΩ
MUTE 30kΩ
OFF
SW9 For pilot cancellation testing
When pilot cancellation is used When pilot cancellation is not used
SW10 Mute off (pin 33)
MUTE OFF
MUTE ON
(b) Trimmers (variable resistors)
VR1 Separation adjustment
VR2 Pilot cancellation adjustment
(5) Test Points
(a) DC voltages
VD1 FM RF AGC voltage
VD2 AM/FM SD, AM Tweet, FM stereo indicator
VD3 AM/FM S-meter
VD4 MRC output
VD5 Mute drive output
VD6 AM antenna damping voltage
VD7 N.C. Gate time
Pin 2
Pin 26
Pin 24
Pin 27
Pin 33
Pin 46
Pin 8
(b) AC voltages
VA1 AM/FM OSC Buff
VA2 First IF output
VA3 IF counter buffer
VA4 MPX OUT Left ch
VA5 MPX OUT Right ch
Pin 4
Pin 53 → CF → pin 51 load level (10.7MHz)
Pin 23 (10.7MHz/450kHz)
Pin 15 (AF)
Pin 16 (AF)
No.6038-5/48