DDP3310B Datasheet, PDF (19/60 Pages) Micronas – Display and Deflection Processor

ADVANCE INFORMATION
DDP 3310B
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.
Vertical
Sawtooth
East/West
Parabola
Start
Stop
Normal
Fig. 2–16: Vertical zoom
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 of 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.
Vert. Protection Flag
1
Accu
−1
Blanking
Fig. 2–17: Protection timing
~10 fields
~40 fields
t
Micronas
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