LA7510 View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LA7510 Datasheet PDF : 5 Pages
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Continued from preceding page.
Pin No.
6
LA7510
Internal Circuit
Unit (resistance : Ω)
Description
Detector output.
The output stage is an emitter-follower. The external
resistance R is required to match impedances with the
following 4.5MHz ceramic band-pass filter. Note that the
LA7510 has an internal 330Ω resister on the output pin.
9
Transistor detector filter pin.
The filter capacitor should be selected for optimum audio
signal-to-noise. Its value should be less than 85pF, since the
4.5MHz signal drops as the capacitance increases,
increasing the picture/sound carrier level ratio and degrading
audio S/N performance.
Functional Description
1.IF Amplifier
As shown in figure 1, the IF amplifier is a 3-stage balanced circuit. The AGC detector output controls the gain of
all three stages.
Figure 1
2.AGC Detector
The AGC detector , shown in figure 2, is a peak-detection type circuit. Pin 3 is the peak-detection filter capacitor
connection.
Figure 2
3.Transistor Detector and Video Amplifier
The detector circuit is shown in figure 3. The balanced IF signals from the IF amplifier and applied separately to
the bases of the differential pair.
The detector output is taken from the emitters of the differential pair, smoothed by the filter on pin 9, and ampli-
fied by the video amplifier. The video signal (≈0.85/Vp-p) and sound IF signal are output on pin 6 via a 330Ω
resistor.
No.2866–3/5
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