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參數(shù)資料
| 型號： | LA3370 |
| 元件分類： | 接收器 |
| 英文描述： | FM, AUDIO DEMODULATOR, PZIP16 |
| 封裝： | 3 MM PITCH, SIP-16 |
| 文件頁數(shù)： | 6/11頁 |
| 文件大小： | 175K |
| 代理商： | LA3370 |
LA3370
No.619-4/11
Block Diagram and Sample Application Circuit
L OUT
20k
Ω
16
13
15
14
4
3
2
1
9
5
6
7
8
12
10
Phase
comparator
V
oltage
regulator
High
cut
control
Separation
Pilot
detector
Ramp
trigger
Driver
AND
VCO
FF
19k
FF
38k
19kHz
1000pF
C6
C5
C4
VR2
R2
R1
90
°
100k
Ω
10k
Ω
1k
Ω
12k
Ω
R3
1
μF
3.3
μF
C3
VR1
0.01
μF
C2
GND
R OUT
C1
C8
C9
C7
R4
R5
R6
10
μF
10
μF
0.015
μF
0.015
μF
1
μF
+VCC
3.3k
Ω
3.3k
Ω
1k
Ω
+VCC
Separation ad just
High-cut constant
Ripple filter
OSC constants
Buffer
Sub
demodulation
Matrix
Main
High
cut
OSC
stop
Stereo lamp
Stereo
noise
control
(SNC)
High-cut
control
(HCC)
Composite input
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.
(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)
相關(guān)PDF資料 |
PDF描述 |
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| LA3373 | FM, AUDIO DEMODULATOR, PDIP16 |
| LA3375 | SPECIALTY CONSUMER CIRCUIT, PZIP16 |
| LA3376 | SPECIALTY CONSUMER CIRCUIT, PZIP16 |
| LA3401 | AM/FM, AUDIO DEMODULATOR, PDIP22 |
| LA3410 | FM, AUDIO DEMODULATOR, PDIP16 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LA3370-E | 制造商:Sony Semiconductor Solutions Division 功能描述: |
| LA3373 | 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:PLL MULTIPLEX STEREO DEMODULATOR |
| LA3375 | 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:Pilot Cancel-Provided PLL FM MPX Demodulator for Car Stereos |
| LA3376 | 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:Pilot Cancel-Provided PLL FM MPX Demodulator for Car Stereos |
| LA3376M | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Consumer IC |
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