SANYO LA3370 Datasheet
LA3370
Ordering number : EN619H
PLL FM Multiplex Stereo Demodulator
for Car Stereo
Monolithic Linear IC
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
63097HA (KOTO) / 8288YT/3018TA/5205MW, TS No.619-1/11
Overview
The LA3370 is a multiplex IC for FM car stereo, and it has
the following 2 functions through its utilization of the IF
meter output voltage, etc.
1. Stereo noise control (SNC) under which the noise
particular to the FM stereo unit in the weak electric
field is reduced smoothly.
2. High-cut control (HCC) under which the high
frequency is smoothly attenuated. In additioin, the
LA3370 can be, due to its low distortion factor, an IC
for multiplex stereo demodulator which is appropriate
for the car component stereo unit.
Functions
• Stereo noise control (SNC terminal)
Through controlling the quality of sound from stereo mode to monaural mode with the voltage applied to the control
pin, the FM stereo noise in the weak electric field is reduced by this function.
• High-cut control function (HCC terminal)
The FM noise in the weak electric field is reduced through the attenuation of high frequency thereof.
Such attenuation can be changed smoothly from "Normal" to "High Cut" by controlling the voltage applied to the
control pin. The volume of "High Cut" can be selected by using an external capacitor.
• Stereo-monaural automatic select
This selection has priority over the stereo noise control. Pilot input prioritized.
• Stoppage of VCO oscillation
When a voltage of 7.5V or higher is applied to the HCC terminal, the oscillation of VCO can be discontinued. In this
case, the stereo lamp does not malfunction.
• With separation control terminal.
Features
• Low distortion factor. (0.05% typ. 300mV input, mono)
• The ripple of power source can effectively be rejected. (35dB typ.)
• The range of voltage to be used is wide. (VCC=6.5 to 14V)
• The space factor is advantageous because of the single-end package.
• The printed circuit board can easily be prepared as 3mm pitch is used between the pins.
Package Dimensions
unit: mm
3020A-SIP16
[LA3370]
SANYO: SIP16
LA3370
No.619-2/11
Specifications
Maximum Ratings
at Ta=25°C
Parameter Symbol Conditions Ratings Unit
Maximum supply voltage VCCmax 16 V
Lamp driving current I
L
40 mA
Allowable power dissipation Pd max Ta≤45°C 520 mW
Operating temperature Topr –20 to +70 °C
Storage temperature Tstg –40 to +125 °C
Recommended Operating Conditions at Ta=25°C
Parameter Symbol Conditions Ratings Unit
Recommended supply voltage V
CC
6.5 to 14 V
Input signal voltage V
IN
200 to 300 mV
Operation Characteristics at Ta=25°C, V
CC
=10V, VIN=300mV, f=1kHz, L+R=90%, pilot=10%
See specified Test Circuit.
Parameter Symbol Conditions
Ratings
min typ max
Unit
Quiescent current Icco 21 27 mA
Channel separation Sep 40 50 dB
Monaural distortion mono THD Mono=300mV 0.05 0.2 %
Stereo distortion ST THD Main 0.05 0.2 %
Lamp turning-on level V
L
L+R=90%, pilot=10% 60 85 120 mV
Hysteresis hy 3 6 dB
Capture range CR Pilot=30mV ±3 %
Output signal level V
O
Sub 140 200 280 mV
S/N ratio S/N 70 78 dB
Input resistance r
i
20 kΩ
SCA rejection SCArej 80 dB
Allowable input voltage V
IN
THD=1% 700 800 mV
SNC output attenuation AttSNC V8=0.6V, L–R=90%, pilot=10% –8.5 –3.0 –0.3 dB
SNC output voltage VOsub V8=0.1V, L–R=90%, pilot=10% 5 mV
HCC output attenuation AttHCC 1 V7=0.6V, L+R=90%, pilot=10% –15.0 –6.0 –0.5 dB
AttHCC 2 V7=1V, L+R=90%, pilot=10% –2.0 0 dB
Power ripple rejection Rr 35 dB
VCO stopping voltage VCOstop 6.8 V
Channel balance CH Ba 0.5 1.5 dB
Test Circuit
LA3370
No.619-3/11
SNC (stereo noise control) and HCC (high-cut control)
The LA3370 has SNC and HCC terminals for improved S/N ratios when operating in weak radio fields. By adjusting
the SNC terminal, noises unique to stereo FM in weak fields can be reduced. The HCC terminals permits further
improvement of effective S/N ratios by lowering treble levels of FM noises in weak fields. (See Fig.2)
STEREO deteriorates approximately 21.7dB (compared to MONO) in weak radio fields (Fig.2). Generally, when
S/N ratios deteriorate below 30 to 40dB, noises become quite noticeable. Section (1) shows ways to set SNC and
HCC when radio field strengths are divided into 3 regions, A, B, and C (Fig.2). SNC is expected to function in region
A, and HCC in region B. In region C, shallow muting is effected in the IF stage.
Sample Application Circuit and Equivalent Circuit Block Diagram
LA3370
No.619-4/11
(1) SNC (stereo noise control)
Stereo S/N ratios deteriorate 21.7dB below monaural but can be improved by varying stereo separation. S/N
improvement becomes apparent, however, only when the separation is 20dB or worse. In that case, the relation
between separation and S/N improvement is shown in Fig.3.
SNC in the LA3370 improves S/N ratios in weak radio fields by varying separation. It varies subsignal
demodulation level and controls separation. By using the IF stage signal meter level output as the source of the
control signal, S/N ratios in region A of Fig.2 can be maintained at about 40dB or better. Ideal S/N enhancements
should provide gradual switching over from stereo to monaural to maintain constant S/N ratios, starting from a point
in region A for 40dB stereo S/N toward a point for 40dB monaural S/N. Methods to set the control level will be
described later.
Fig.4 shows voltages applied to pin 8 (SNC terminal) of LA3370 versus separation characteristics (SNC
characteristics). Pin 8 is also the base of a PNP transistor, so stereo mode is set when pin 8 is open and monaural
mode is set when it is grounded. SNC terminal control is effective only when locked with pilot signals and when
stereo indicator is lit. External circuit parameters can be chosen in large values that do not affect the IF stage meter
output circuit because SNC control currents are small. This makes designing easy. (See Fig.5)
(2) Designing external circuits for SNC characteristics (characteristic setting by drawing)
We recommend the following as a way to adjust SNC characteristics to have smooth transition of separation from
stereo monaural in region A of Fig.2.
Separation vs. S/N enhancement relation……………………… Refer to Fig.3.
SNC pin voltage vs.separation characteristics………………… Refer to Fig.4.
Antenna inputs vs. S/N improvement characteristics can be obtained from the drawing if the graph for IF stage
signal meter output vs. antenna input and the graph for stereo S/N ratio vs. antenna input are known. From desired
S/N characteristics, SNC terminal voltage characteristics can also be obtained. Sample drawings are shown in Fig.6,
where for simplicity's sake, SNC, IF meter, and stereo S/N characteristics have been approximated with straight
lines.
For instance :
To obtain stereo S/N improvement characteristics from SNC characteristics, when (a) in the second quadrant
of the chart represents bare SNC characteristics, point 1 projected to the third quadrant shows a 20dB
separation and a 1dB S/N improvement. When projected from the first to the fourth quadrant, a point
improved by 1dB in S/N over the stereo S/N line in the fourth quadrant corresponds to point 1. Similarly,
point 2 on the SNC characteristics in the second quadrant corresponds to point 2 in the fourth quadrant. Point
3 in the second quadrant corresponds to point 3 in the fourth quadrant. Stereo S/N improvement characteristics
for each point are obtainable. Similarly, (b) characteristics in the second quadrant are projected to form (b)
characteristics in the fourth quadrant, and (c) in the second quadrant to form (c) in the fourth quadrant, thus
providing a way to diagram improvement characteristics.
In the resulting drawings, ideal S/N improvement characteristics are similar to (b) in the fourth quadrant, but
corresponding SNC characteristics have to be (b) characteristics in the second quadrant which are difficult to realize.
Among realistic characteristics, something like (c) appears to be satisfactory. The (c) SNC characteristics are
obtained with a shift by two diodes together with a 1/2 bleeder.
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