VDP3104B Ver la hoja de datos (PDF) - Micronas

Número de pieza

componentes Descripción

Fabricante

VDP3104B

Video Processor Family

Micronas 

VDP 31xxB

PRELIMINARY DATA SHEET

2.11.3. Vertical and East/West Deflection

The calculations of the vertical and East/West deflection

waveforms is done by the internal Fast Processor (FP).

The algorithm uses a chain of accumulators to generate

the required polynomial waveforms. To produce the

deflection waveforms, the accumulators are initialized at

the beginning of each field. The initialization values must

be computed by the TV control processor and are written

to the front-end once. The waveforms are described as

polynomials in x, where x varies from 0 to 1 for one field.

P: a + b(x–0.5) + c(x–0.5)2 + d(x–0.5)3 + e(x–0.5)4

The initialization values for the accumulators a0..a3 for

vertical deflection and a0..a4 for East/West deflection

are 12-bit values.

The vertical waveform can be scaled according the

average beam current. This is used to compensate the

effects of electric high tension changes due to beam cur-

rent variations. In order to get a faster vertical retrace

timing, the output impedance of the vertical

D/A-converter can be reduced by 50% during the re-

trace.

Fig. 2–30 shows several vertical and East/West deflec-

tion waveforms. The polynomial coefficients are also

stated.

2.11.4. Protection Circuitry

– Picture tube and drive stage protection is provided

through the following measures:

– Vertical flyback protection input: this pin searches for

a negative edge in every field, otherwise the RGB

drive signals are blanked.

– Drive shutoff during flyback: this feature can be se-

lected by software.

– Safety input pin: this input has two thresholds. Be-

tween zero and the lower threshold, normal function-

ing takes place. Between the lower and the higher

threshold, the RGB signals are blanked. Above the

higher threshold, the RGB signals are blanked and the

horizontal drive is shut off. Both thresholds have a

small hysteresis.

– The main oscillator and the horizontal drive circuitry

are run from a separate (standby) power supply and

are already active while the TV set is powering up.

Vertical:

a,b,c,d

0,1,0,0

0,1,1,0

0,1,0,1

Fig. 2–30: Vertical and East/West deflection waveforms

East/West:

a,b,c,d,e

0,0,1,0,0

0,0,0,0,1

0,0,1,1,1

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