LA3430 View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LA3430 Datasheet PDF : 12 Pages
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LA3430
Cautions when employing sample application circuits
· Adjust separation by 10kΩ potentiometer in low pass filter.
· Adjust RS for noise detection sensitivity under strong to medium radio fields. Set at adequate value.
· Adjust noise AGC by CY and RY to enhance noise suppression in medium to weak radio fields.
· Adjust pilot cancellation by 50kΩ potentiometer connected to pin 15 of LA2110.
· Reponse speeds of pilot cancellation to follow levels can be varied by adjusting capacitance value of 1µF capacitor
connected across pins 11 and 12 of LA3430. Distortion factors deteriorate with reduction in value.
· Adjusting pilot cancellation.
For example consider the sample application circuit 2. Assume the input signal consists only of pilot signals. First
connect an oscilloscope and a valve voltmeter to pin 2 of LA2110. Set their ranges for V : 200mV/div. AC, H : 20µs/
div.
Then, adjust pilot cancel control to minimize indications of valve voltmeter.
When the LA3430 alone is used (sample application circuit 1), adjust cancel control through a 19kHz B.P.F. to
minimize carrier leakage level at output pins (pins 5 and 6).
1. Pilot cancelling circuit
A level-following type has been used. Once set, it can easily accommodate varying pilot modulation depths among
stations. Cancelling signal is a sawtooth wave obtained by integrating a square wave that is proportionate in ampli-
tude to pilot level with C and R.
2. Separation adjustments
The LA3430 has separation parameters that have been set to provide maximum separation when used in conjunction
with the LA2110, a noise-canceler IC, or the equivalent. The LA3430 by itself exhibits separation only in a 25 to 30
dB range. If a phase correction circuit is provided in the LA3430 input circuit, it can exhibit intrinsic separation
charactersitics, typically 50 dB.
3. SNC (stereo noise control) and HCC (high-cut control)
The LA3430 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 21.7 dB (compared to MONO) in weak radio feilds (Fig. 2). Generally, when
S/N ratios deteriorate below 30 to 40 dB, noises become quite noticeable. Section (1) shows ways to set SNC and
HCC when radio field strenghs 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.
No.1408–5/12
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