LA1787M Datasheet, PDF (42/54 Pages) Sanyo Semicon Device – Single-Chip Tuner IC for Car Radios

LA1787M
5. 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.
20 kΩ
To the
VO
matrix
(dB)
41
C
Fig. 45
A12090
1
f_C = —2_π—_×—C—_× —20—k_Ω— [Hz]
1
2πC × 20 kΩ
Fig. 46
f
(Hz)
A12091
Frequency Characteristics Fig.47
10
Changes in the pin 41 capacitor capacitance (for a 100% high cut ratio)
0
0.001 µF
–10
0 _µF
0.0022 µF
–20
0.0047 µF
–30
–40
–50 ^{VCC = 8.0 V}
f = 98 MHz 100%mod
80 dBµ IN
–60
3 5 7 ₁₀₀
23
5 7 _1k
2 3 5 7 _10k 2 3
Frequency, f — Hz
• Pilot canceler adjustment (pins 17 and 18)
Noise
canceler
30
input
–
To the
multiplexer
Gate
Pilot
cancel
11
12 17
18
6800 pF 3.9 kΩ 0.01 µF 50 kΩ
A12092
Fig. 48
The pilot canceler signal waveform (pin 19) is a 19 kHz 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. 6655-42/54