la7975 Sanyo Semiconductor Corporation, la7975 Datasheet - Page 4

• Manufacturer Part Number: la7975
• Description: Pal Multi-system Sif Converter
• Manufacturer: Sanyo Semiconductor Corporation

From video
output section
(Pin 4 oscillation waveform)
Unit (resistance:
Figure 1
Figure 2
Figure 4
Figure 5
Figure 6
Unit (resistance:
Unit (resistance:
, capacitance: F)
LA7975
)
)
.
.
Pin 1 is the SIF input pin.
The filter in Figure 2 can be connected to the input section
to improve the buzz characteristic.
Figure 3 shows the characteristics for the filter in Figure 2.
If C1 is too small, the buzz characteristic improves for
normal input, but the filter cuts into the sound carrier and the
buzz characteristic deteriorates for the P/S (picture/sound
carrier) ratio.
Use C1 6 20 pF to 47 pF.
Pin 4 is the ceramic oscillator pin.
To make the oscillation waveform approach a sine wave,the
oscillation level is controlled internally.
Oscillation levels of 15 to 80 mVp-p at Pin 4 give the
waveform shown in Figure 5.
To stop oscillation, attach an external resistor as in Figure 6
and switch S1 on.
Here are the conditions for handling multiple systems.
Input frequency
5.5 MHz
6.0 MHz
6.5 MHz
4.5 MHz
Figure 8 shows a proposed multi-system
Filter characteristic
Oscillation stop
Frequency – Hz
Figure 3
Figure 7
Figure 8
Oscillator
500 kHz
500 kHz
1.5 MHz
Unit (resistance:
(Multi-system implementation)
Unit (resistance:
, capacitance: F)
(pass through)
Pin 5 output
6 MHz
6 MHz
6 MHz
6 MHz
No.3994-4/6
)