LA1781M_09 Datasheet, PDF (38/48 Pages) Sanyo Semicon Device – For Car Radios Single-Chip Tuner IC

LA1781M
8. Multiplexer Block
• HCC (high cut control) frequency characteristics (pin 41)
When the HCC function operates, the frequency characteristics of the output signal are determined by the capacitance
of the external capacitor connected to pin 41.
20kΩ
To The
VO
Matrix
(dB)
41
C
Fig. 45
fC =
1
2π × C × 20kΩ
[Hz]
Frequency Characteristics Fig. 47
10
Changes in the pin 41 capacitor capacitance (for a 100% high cut ratio)
0
0.001μF
--10
0_μF
0.0022μF
--20
0.0047μF
--30
--40
--50 VCC = 8.0V
f = 98MHz 100%mod
--60 ^{80dBμ IN}
3 5 7 ₁₀₀ 2 3 5 7 _1k 2 3 5 7 _10k 2 3
Frequency, f -- Hz
• Pilot canceler adjustment (pins 17 and 18)
1
2πC × 20kΩ
f
(Hz)
Fig. 46
NCoise
canceler
30
input
--
To the
multiplexer
Gate
Pilot
cancel
11
12 17
18
6800pF 3.9kΩ 0.01μF 50kΩ
Fig. 48
The pilot canceler signal waveform (pin 19) is a 19kHz signal that contains no third harmonic as shown in figure 48.
Since this signal has the same phase as the pilot signal, no capacitor is required between pin 18 and ground.
Since it has no third harmonic component, excellent pilot cancellation can be acquired in both the left and right
channels by adjusting with a variable resistor.
No.6038-38/48