Samsung Wingo S-2450, Service Manual

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Samsung Electronics 10-13
IC Internal Diagram
10-5 LA1837 ; TIC1
Overview
The LA1837 is a single-chip AM/FM IF and MPX IC that
supports electronic tuning and was developed for use in
home stereo systems. It is optimal for use in automatic
station selection systems that use the SD and IF counting
techniques.
Functions
AM: RF amplifier, mixer, oscillator, IF amplifier,
detector AGC, oscillator buffer, S-meter, narrow-
band SD, IF buffer
FM IF: IF amplifier, quadrature detector, S-meter, S-
curve detector, IF buffer output
MPX: PLL stereo decoder, stereo display, forced mono,
VCO stop, post amplifier, audio muting, adjacent
channel interference rejection function
Features
• On-chip MPX VCO (no external components required)
• Adjacent channel interference rejection function
(third and fifth order)
• Supports both the SD and the IF counting techniques.
• The AM and FM SD sensitivities can be set independently.
• The AM and FM output levels can be set independently.
• Improved AM practical sensitivity and high-input
distortion characteristics
Package Dimensions
unit: mm
3061-DIP30S
Monolithic Linear IC
Ordering number : EN5688
SANYO: DIP30S
[LA1837]
Single-Chip Home Stereo IC with
Electronic Tuning Support
LA1837
Parameter Symbol Conditions Ratings Unit
Maximum supply voltage V
CC
max 12 V
Allowable power dissipation Pd max Ta
≤
70°C 550 mW
Operating temperature Topr –20 to + 70 °C
Storage temperature Tstg –40 to +125 °C
Specifications
Maximum Ratings at Ta = 25°C
Parameter Symbol Conditions Ratings Unit
Recommended supply voltage V
CC
9 V
Operating voltage range V
CC
op 7 to 11 V
Operating Conditions at Ta = 25°C