TC90A13F

The TC90A13F separates luminance (Y) and chrominance (C) signals from an NTSC composite video signal. It employs the Toshiba original logical comb filter to realize high performance Y/C separation at low cost.

Features of the TC90A13F are:(1)NTSC system; (2)PLL 4X multiplication circuit; (3)sync. tip clampping circuit; (4)8bit A/D converter; (5)8bit D/A converters (2ch); (6)2H line memory; (7)dynamic comb filter; (8)1 line dot correction circuit; (9)vertical enhancer; (10)color killer mode (Y/C separation OFF); (11)chrominance wide band output mode; (12)SDIP28/SOP28 package; (13)5V single power supply.This block enhances the uncorrelated components among the three lines of the luminance signal following coring. There are three enhancement level selections of HIGH (1.9dB), MID (1.OdB) and LOW 0.5dB).The luminance signal, obtained by subtracting the chrominance signal from the composite video signal, is added to the vertical edge enhancement component and output through the D/A converter. However, this output signal is limited to the pedestal level (fixed internally) by the pedestal clipping circuit (except for the sync tip level).

The absolute maximum ratings of the TC90A13F can be summarized as:(1)power supply voltage:Vss to Vss+6.0 V;(2)input voltage:-0.3 to Vdd+0.3V;(3)storage temperature:-55 to 125;(4)power dissipation:600mW.In this block, with fsc as the center frequency of the BPF, the chrominance signal is extracted from the OH, 1 H and 2H delayed composite video signal. Since the BPF for the chrominance signal output can be controlled (ON or OFF), the chrominance output can therefore be switched between a narrow band width and a wide band width.This block comprises a band-pass filter that extracts the vertical component of the chrominance signal. Using Toshiba original logic, a correlation of the three lines is sought for. The absence of correlation is taken as an indication of a luminance signal, at which time chrominance signal output is suppressed.Previously, a 1-line-only chrominance signal was processed as a luminance signal resulting in dot crawl. This circuit prevents this problem by extracting the 1-line dot component and adding it to the dynamic comb filter output. This circuit block can be set ON or OFF.