UPC1830GT NEC, UPC1830GT Datasheet - Page 15

• Manufacturer Part Number: UPC1830GT
• Description: FILTER-CONTAINING VIDEO CHROMA/ SYNCHRONIZING SIGNAL PROCESSING LSI COMPATIBLE WITH NTSC/PAL SYSTEM
• Manufacturer: NEC

(5) Subcolor control circuit
(6) Chroma APC (Auto Phase Control) circuit
(7) Killer detection circuit
(8) IDENT detection circuit
(9) 3.58 MHz/4.43 MHz VCXO, PAL SW circuit
(10) R-Y, B-Y demodulation circuit
According to the voltage of the subcolor control pin (pin 37), controls the amplitude of the chroma signal output from
the ACC amplification circuit after separating the burst signal from it, and adjusts the amplitude of the color difference
signal output from the R-Y output pin (pin 13) and B-Y output pin (pin 14). This controls color density on the screen.
The control characteristic is shown in Figure 5-2.
Detects the phase difference between the burst signal extracted from the chroma signal and the signal from f
and smoothes the chroma APC filter pin (pin 30) using a capacitor. This smoothed voltage is used to control the
f
Detects the amplitude of the burst signal and executes a mute on the subcolor control circuit when there is no burst
signal, preventing it from outputting a chroma signal to avoid color noise. In this case, the output of the color killer
output pin (pin 8) is driven high.
The color killer sensitivity is determined by the time constant of a resistor and capacitor connected to the color killer
filter pin (pin 26).
Performs IDENT detection. With IDENT detection, if an NTSC signal (PAL signal in NTSC mode) is input in PAL mode,
the color killer turns on and no chroma signal is output.
Switches the f
of the f
oscillation at 3.58 MHz or 4.43 MHz. VCXO is controlled by the voltage of the chroma APC filter pin (pin 30) smoothed
by the chroma APC circuit and its phase is synchronized with the input burst signal.
The PAL SW circuit inverts the phase of a signal on the R-Y demodulation axis every 1H by IDENT detection.
SC
Performs demodulation using the chroma signal output from the ACC circuit, an R-Y demodulation axis signal and
a B-Y demodulation axis signal output from f
VCXO oscillation frequency.
3
2
1
0
SC
Color bar (composite, burst: 300 mV
switching pin (pin 41) (2.8 V or higher: 3.58 MHz mode, 2.2 V or below: 4.43 MHz mode) to perform f
SC
(a) NTSC mode
1
Subcolor control pin voltage (V)
VCO input pin between pin 28 (for 3.58 MHz) and pin 29 (for 4.43 MHz) by controlling the voltage
2
Figure 5-2. Subcolor Control Characteristic
3
V
4
CC
p-p
) input
= 5 V
SC
VCXO, and multiplies R-Y by 1.4 and B-Y by 2.03.
5
3
2
1
0
Color bar (composite, burst: 300 mV
1
Subcolor control pin voltage (V)
(b) PAL mode
2
3
V
4
CC
PC1830
p-p
) input
= 5 V
SC
VCXO
5
15
SC