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LA1137N Schematic ( PDF Datasheet ) - Sanyo Semicon Device

Teilenummer LA1137N
Beschreibung AM Tuners for Car Radios and Home Stereos
Hersteller Sanyo Semicon Device
Logo Sanyo Semicon Device Logo 




Gesamt 28 Seiten
LA1137N Datasheet, Funktion
Ordering number: EN 3507
Monolithic Linear IC
LA1136N, 1136NM, 1137N, 1137NM
AM Tuners for Car Radios and Home Stereos
Overview
The LA1136N/NM and LA1137N/NM are high-performance
AM electronic tuner ICs offering sophisticated functions. They
are especially suited for use in car radio and home stereo
(antenna: loop) applications.
Functions
. MIX
. OSC (with ALC)
. IF amplifier
. Detector
. AGC (normal)
. RF wide-band AGC
. Auto search stop signal (Signal meter output)
. Local oscillation buffer output
. IF band switching circuit (for LA1136N only)
. IF count buffer
. Stop detector output (can be set independently)
. Tweet prevention circuit
. AGC (RF, IF) time constant switching circuit
. IF AGC circuit
. Pin-diode driver
. AM stereo decoder IF output (for LA1136N only)
. Circuit preventing incorrect seek operation
Features
. Excellent cross modulation characteristic: Meets the
requirements for preventing not only adjacent-channel
interference but also interference caused by all channels
. within broadcast band.
Narrow-band signal meter output: Usable as auto search stop
. signal. Has linearity up to 100 dBµ.
Local oscillation buffer output: Facilitates designing of
. electronic tuner system, frequency display, etc.
OSC (with ALC): Improves tracking error because
oscillation output is stabilized at a low level (350 mVrms:
. LA1137N) for varactor diode.
MIX: Double-balanced differential MIX meeting the
requirements for preventing spurious interference, IF
. interference.
Good characteristic at high input: 130 dBµ input
fm = 400 Hz 80%mod THD = 0.5% typ.
. High S/N: Good S/N at medium input (55 dB typ).
. Usable sensitivity: (S/N = 20 dB input): 25 dBµ
. (when using 2SK715 )
VCC variation compensation: Less variation in gain,
distortion: 8 to 12 V
AM stereo capability (LA1136N only)
. IF band switching circuit on chip; controlled by
. microcontroller
Oscillating circuit for AM stereo; SUB S/N improved to
6 dB
. IF output for AM stereo decoder
. Improved tweet characteristics: 10 dB increase, controlled by
. microcontroller
Improved cross modulation characteristics, especially
sensitivity suppression characteristics: 15 dB improvement,
wide-band AGC operation even for SW band interference
. Improved low-frequency modulation distortion
. Improved temperature characteristics: S-meter, SD sensitivity
. Faster RF AGC response: RF: 1/3; IF: 1/8 (compared to
. predecessors)
Improved capability for driving external RF AGC transistors:
IB max = 200 µA
. Measures to prevent incorrect seek operation
. IF count buffer on chip; controlled by microcontroller
. Time constant switching circuit on chip for RF and IF
AGC
. IF AGC clear circuit on chip
. Measures that prevent stopping one station too soon
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
93097HA(II)/4281TS(US) No.3507-1/28






LA1137N Datasheet, Funktion
LA1136N, 1136NM, 1137N, 1137NM
LA1137N, LA1137NM Test Circuit
No. 3507-6/28

6 Page









LA1137N pdf, datenblatt
LA1136N, 1136NM, 1137N, 1137NM
LA1136N, LA1137N Usage Notes
1. Do not connect the antenna alignment circuit and local oscillation circuit.
2. The coils should be specified to obtain an output level of –25 dBm (43.6 mVrms) for the given input levels shown below,
and under the conditions fm = 400 Hz, 30% modulation and fOSC = 1.45 MHz.
Antenna input
Mixer input
IF input
Detector input
20.0 dBµ (Note)
30.5 dBµ
38.0 dBµ
106.0 dBµ
Input connections
Antenna input
Mixer input
IF input
Detector input
V12 = 0 for LA1136N
Unit (resistance: , capacitance: F)
Note : The antenna input can be adjusted by changing the number of turns in the primary winding of the alignment coil in
accordance with the AGC figure-of-merit.
3. Coil Design Notes
(1) RF alignment coil
. Gain adjustment: The gain is adjusted by varying the primary turns ratio of the primary coil.
. Coupling: The design of this coil is geared towards critical coupling.
The coupling is dependent on the turns ratio of the primary coil and the secondary coil:
Tight coupling: High turns ratio
. Loose coupling: Low turns ratio
With tight coupling, the selectivity characteristic develops a double hump; when making a tracking adjustment, it must
. be noted that misadjustment can occur, leading to a deterioration of the dual signal characteristics.
With loose coupling, selectivity increases, but the sensitivity error within the band of the RF alignment itself also
increases.
During design, be certain to confirm data such as that for coil specifications. Furthermore, it is also necessary to note that
although the turns ratio of the primary and secondary coils have the greatest bearing on coupling, the shape of the coil core
and the manner in which the coil is wound also have an impact.
No. 3507-12/28

12 Page





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