DDP3310B datasheet(19/60 Pages) MICRONAS

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ADVANCE INFORMATION

DDP 3310B

Micronas

2.3.7. Vertical Zoom

With vertical zoom, the DDP 3310B is able to display

different aspect ratios of the source signal on tubes

with 4:3 or 16:9 aspect ratio by adapting the corre-

sponding raster.

Fig. 2–16: Vertical zoom

2.3.8. EHT Compensation

The vertical deflection waveform can be scaled

according to the average beam current. This is used to

compensate

the

effects

electric

high-tension

changes due to beam current variations. EHT compen-

sation for East/West deflection is done with an offset

corresponding to the average beam current. The time

constant of this process is freely programmable with a

resolution of 18 bit. Both corrections can be enabled

separately. The maximum scaling coefficient for verti-

cal deflection is 1

±x and the maximum offset for East/

West is y, where x, y are adjustable from 0 to 0.25. The

horizontal phase at the output HOUT can be influ-

enced according to the average beam current in a

range of

±1.5 µs.

2.3.9. Protection Circuitry

Picture tube and drive stage protection is provided

through the following measurements:

– Vertical protection input: this pin watches the verti-

cal sawtooth signal. In every field the sawtooth must

descend below the lower threshold A and ascend

above the upper threshold B. In this case the protec-

tion flag is set (sawtooth o.k.). If an error occurs the

protection flag is cleared.

After approx. 10 fields with cleared flag, the RGB

drive signals are blanked. The blanking is cancelled

if the flag is set for 40 fields (see Fig. 2–17).

– Drive shutoff during flyback: this feature can be

selected by software (EFLB)

– Safety input pin: This pin has two thresholds. The

applied signal has to meet the following conditions:

1. threshold B must not be overshot

2. threshold A has to be exceeded permanently or

at least once per line

otherwise the RGB signals are blanked . Both

thresholds have a small hysteresis.

Fig. 2–17: Protection timing

Stop

Start

Vertical

Sawtooth

East/West

Parabola

Zoom

Normal

Vert. Protection Flag

Accu

Blanking

−1

~10 fields

~40 fields

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