LA1136N Datasheet, PDF (17/28 Pages) Sanyo Semicon Device – AM Tuners for Car Radios and Home Stereos

LA1136N, 1136NM, 1137N, 1137NM
10. Application Circuit using the IF count method
The LA1136N and LA1137N can be configured for tuning using either the stop detector or the IF count method. The application
circuits are examples of tuners using the IF count method. The stop detector can be used in any of the application circuits by
making the circuit modifications shown below.
Ω
The other pins are the same as those shown in the application circuits.
11. Improving Fidelity
Distortion for low-frequency(fm % 100 Hz), high-modulation signals can be reduced by increasing the capacitance connected to
RF AGC of pins 1 and 2 (LA1136N, LA1137N). However, increasing this capacitance (C₂) by a large amount can increase the
AGC response time to an unacceptable level.
12. Loop Antenna Specifications
The recommended loop antennae for the LA1136N and LA1137N are the Korin 42579719100 (LA-1500) and 4257976000
(LA-100A). Note that these are the same antennae previously recommended for the LA1135.
13. AGC ON Level Frequency Characteristics
The frequency at which the sensitivity decreases by –3 dB from the point when f = 1 MHz is as shown below.
LA1136N, LA1137N
LA1135
Normal
37 MHz
20 MHz
Wideband
24 MHz
7 MHz
In other words, in AGC for the main signal, the point at which the AGC sensitivity drops 3 dB is 37 MHz, as shown in the
diagram below. The AGC ON level –3 dB frequencies for narrowband and wideband AGC have been extended from those of the
LA1135 to cover the entire SW3 shortwave band. As a result, the wideband AGC sensitivity is significantly increased and
susceptibility to shortwave interference, reduced. This has been achieved without any increase in dispersion or distortion.
Narrowband AGC ON level
AGC ON level variation ± 1 dB up to 30 MHz
Wideband AGC ON level
fr = 1 MHz
LA1136 RF AGC ON mixer input frequency – Hz
Pin 3 input – dBµ
Unit (resistance: Ω, capacitance: F)
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