LA1136N Datasheet, PDF (12/28 Pages) Sanyo Semicon Device – AM Tuners for Car Radios and Home Stereos

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 f_OSC = 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: Ω, 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