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XV-Cl
ou
BRIGHT (pin No. 43)
Used to receive DC voltage for brightness
adjustment.
GAMMA 1, GAMMA 2 (pin Nos. 44 and 45)
Used to receive DC voltage to set a
gamma-correction
DC voltage
gain
switching
point.
(See the figure at
right.) The Gamma 2 terminal is pre-
set inside the IC.
PEAK
LIMITER
output
PEAK LIMITER (pin No. 46)
Used to receive DC voltage to set the
white peak limiter level for primary-
color output.
Input
SUB CONTRAST
B (pin No. 47)
Used to receive DC voltage for fine adjustment of the B signal's contrast.
This terminal is preset inside the IC.
SUB CONTRAST
R (pin No. 48)
Used to receive DC voltage for fine adjustment of the R signal's contrast.
This terminal is pre$et inside the IC.
ii) Circuit behavior
ACC detector, ACC amplifier
They form an ACC loop and serve to detect the peak of the burst signal amplitude.
VCO, APC detector
The VCO local oscillation
circuit is of Pierce crystal oscillator type and functions as a crystal unit. The APC
detector phase-detects
the burst signal and the VCO oscillation output signal. The resulting detection voltage
is used to control the VCO's oscillation frequency and to form a phased-locked
loop. By doing so, no readjust-
ment is needed.
Killer detector
The detector is used to phase-detect
the burst signal and the VCO's oscillation
output signal.
Picture adjustment
circuit
The value "Q" of the luminance
signal delay line is changed in order to adjust the frequency
characteristic.
AGC circuit
Various AGC characteristics
can be achieved
depending
on the luminance
signal's APL.
The luminance
signal is fed to the filter at pin (17) to get rid of the high-frequency
components.
The resulting signal goes to
the AGC detector to detect the peak.
Filter adjustment
The resistance between pin (12) and GND can be regulated to adjust the filter's frequency characteristic.
External input switch
The INT and EXT signals can be switched over by the control signal coming to pin (1). The switch is of high-
speed type.
38
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