|
|
PDF LA1235 Data sheet ( Hoja de datos )
| Número de pieza | LA1235 | |
| Descripción | FM IF System Applications | |
| Fabricantes | Sanyo Semicon Device | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LA1235 (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
Ordering number : EN873F
Monolithic Linear IC
LA1235
FM IF System Applications
Overview
Package Dimensions
The LA1235 is a high integrated IC developed for use in unit: mm
high S/N, low distortion FM IF system applications. This 3006B-DIP16
IC features S/N=88dB, distortion factor=0.015% and has
almost all functions required for FM tuner IF stage.
[LA1235]
The IF amplifier and limiter stage consist of 6 stages of
double ended differential amplifier having an excellent
AMR, and this stage is followd by the signal meter driver
which consists of 4 stages of level detector, thereby
creating extended linearity up to strong input. The FM
detector stage consists of a double balanced quadrature
detector to which a low frequency preamplifire and a
muting controller are attached. The muting drive stage
consists of an OR circuit for weak signal muting drive
SANYO: DIP16
output which detects signal intensity and detuning muting Functions
drive output which detects S curve DC output and enables
the prevention of noise at the time of weak signal and
detuning. Further, the weak signal muting drive output
circuit contains a Schmitt circuit having hysteresis and
enables the prevention of muting malfunction due to
amplitude component at the time of weak signal. The AFC
output and tuning meter drive stage is of current drive type
which makes it possible to adjust AFC sensitivity and
muting band width by means of an external resistor, and
the built-in tuning meter null (short) circuit foreces the
tuning meter to be [0] when th IF amplifier stops working.
• IF amplifier, Limiter.
• Quadrature detection.
• AF preamplifier.
• Signal intesity muting drive output.
• Detuning muting drive output.
• AF signal muting circuit.
• Signal meter drive output.
• AFC, tuning meter drive output.
• IF amplifier stop circuit.
• Tunig meter null circuit.
The IF amplifier stop circuit, being a circuit to stop the FM
IF amlifier at the time of AM reception, makes it possible
to decrease shock noise due to FM-AM receiving mode
switchover.
Features
• High S/N (88dB typ.).
• Low distortion (0.015% typ.).
• Weak signal muting dirve output having hysteresis.
• Tuning mete null (short) circuit.
• Signal meter dirve output having wide dynamic range.
• High limiting sensitivity.
• Built-in constant-voltage regulated circuit (Operating
voltage : 10 to 14V).
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
O2097HA (KT)/63095HA (KOTO) /O076AT/8044KI, TS/4241KI/3091KI No.873-1/12
1 page  
LA1235
• Setting of muting circuit constnats
Drive current to be output at muting drive output pin 12 is 0.75mA typ., but
approximately 0.4mA may be caused by variations in characteristic or
changes in temperature (smaller at higher temperatures). It is desirable to
design the circuit so that the total current to be output from pin 12 at the time
of muting ON does not exceed 0.35mA. When driving the muting circuit of
the LA1235, the muting drive current (input current at pin 5) must be
considered besides this total output current. The muting drive current of the
LA1235 is 0.2mA max.
Thus, the muting constants are obrained as follows. If the muting drive
current is IR207≥0.2mA, R207≤14kΩ occurs and the total current It is shown
by the following expression.
Muting Circuit
It=IR206+IR207=
6.2V
R206
+
4.8V
R206+10kΩ
(10kΩ : Input resistance at pin 5, Refer to the above figure.)
If R207=10kΩ is taken with the variation s in voltage V12 at pin 12 and input resistance 10kΩ at pin 5 considered,
R206≈56.4kΩ is obtained, and then R206=68kΩ and R207=10kΩ are obtained.
• Setting of C112 (Capacitance between pin 12 and ground)
C112 influences S/N and muting attenuation. S/N is improved 0.5 to 2.0dB by changing C112 from 1µF to 100µF.
Muting attenuation becomes as shown in Mute (att) – fm (next page) characteristic. This phenomenon occurs
because the output at pin 7 appears at pin 6 through pin 10 and capacitance C110 between pin 7 and ground also exerts
influence. The relation between muting attenuation andC110 is such that if C110=2.2µF and C112=220µF, attenuation
at modulation frequency 100Hz becomes –80dB.
AF Output Circuit
No.873-5/12
5 Page 
LA1235
Cain distribution of application circuit
If IC anone is operated without front end, the tuning meter deflects toward plus side at the time of no input. This
phenomenon is caused by the fact that the noise component to be applied to the quadrature multiplication circuit is not
syummetric with respect to 10.7MHz but is shifted toward lower frequency side because the frequency characteristic of
IF amplifier attenuates at high frequencies and the phase shift circuit is of low-pass type. If the formt end is attached and
the noise which passes through the narrowband filter of IF stage and spreads symmetrically with respect to 10.7MHz is
stronger than the noise generated inside the IC, the tuning meter reads 0.As the gain of the front end is decreased, input
limiting sensitivity and usable sensitivity worsen abruptly. This phenomenon is caused by the fact that since the tuning
meter is set to 0 at the time of no input the tuning point of the quadrature circuit must be shifted toward lower frequency
side than 10.7MHz and the demodulation output waveform is deformed asymmetrically at an input in the vicinity of
usable sensitivity. However, if the gain of the front end is too increased, the signal meter poiter does not return to zero
point at the time of no signal.
Sample Application Circuit
Unit (resistance : Ω, capacitance : F)
No.873-11/12
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LA1235.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LA1230 | FM IF System |  Sanyo Semiconductor |
| LA1230 | FM IF |  Sanyo |
| LA1231 | FM IF System | Sanyo Semicon Device |
| LA1231N | FM IF System | Sanyo Semicon Device |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |