M35061 Datasheet, PDF (30/40 Pages) Mitsubishi Electric Semiconductor – SCREEN CHARACTER and PATTERN DISPLAY CONTROLLERS

MITSUBISHI MICROCOMPUTERS
M35061-XXXSP/FP
SCREEN CHARACTER and PATTERN DISPLAY CONTROLLERS
10. Notes on fsc signal input
(1) This IC amplifies the subcarrier frequency (fsc) signal (NTSC sys-
tem: 3.580 MHz, PAL system: 4.434 MHz, M-PAL system: 3.576
MHz) input to the OSCIN pin and generates the composite video
signal internally.
The amplified fsc signal can be destabilized in the following cases.
(a) When the fsc signal is outside of recommended operating
conditions
(b) When the waveform of the fsc signal is distorted
(c) When DC level in the fsc waveform fluctuates
When the amplified signal is unstable, the composite video signal
generated inside the IC is also unstable in terms of synchroniza-
tion with the subcarrier and phase.
Consequently, this results in color flicker and lost synchroniza-
tion when the composite video signal is generated. Make note of
the fact that this may prevent a stable blue background from be-
ing formed.
(2) When switching to internal synchronization from external syn-
chronization (fsc signal is OFF), start fsc signal input 20 m sec or
more before the internal oscillator circuit stabilizes.
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