DDP3300A Datasheet, PDF (14/53 Pages) Micronas – Single-Chip Display and Deflection Processor

DDP 3300 A
PRELIMINARY DATA SHEET
In each field two sets of measurements can be taken:
a) The picture tube measurement returns results for
– cutoff R
– cutoff G
– cutoff B
– white drive R or G or B (sequentially)
b) The picture measurement returns data on
– active picture maximum current
– active picture minimum current
The tube measurement is automatically started when
the cutoff blue result register is read. Cutoff control for
RGB requires one field only while a complete white-drive
control requires three fields. If the measurement mode
is set to ‘offset check’, a measurement cycle is run with
the cutoff/whitedrive signals set to zero. This allows to
compensate the MADC offset as well as input the
leakage currents. During cutoff and whitedrive measure-
ments, the average beam current limiter function (ref.
2.2.3.) is switched off and a programmable value is used
for the brightness setting. The start line of the tube mea-
surement can be programmed via I²C-bus, the first line
used for the measurement, i.e. measurement of cutoff
red, is 2 lines after the programmed start line.
tube measurement
picture meas. start
active video
field 1/ 2
picture meas. end
ÍÍÍ
small window for tube
measurement (cutoff, white drive)
ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ _{large window for active picture}
Fig. 2–12:Windows for tube and picture measure-
ments
2.2.2. SCART Output Signal
The RGB output of the DDP 3300 A can also be used to
drive a SCART output. In the case of the SCART signal,
the parameter CLMPR (clamping reference) has to be
set to 1. Then, during blanking, the RGB outputs are au-
tomatically set to 50% of the maximum brightness. The
DC offset values can be adjusted with the cutoff parame-
ters CR, CG, and CB. The amplitudes can be adjusted
with the drive parameters WDR, WDG, and WDB (lo-
cated in the VPC 3200 A).
The picture measurement must be enabled by the con-
trol microprocessor after reading the min./max. result
registers. If a ‘1’ is written into bit 2 in subaddress 25, the
measurement runs for one field. For the next measure-
ment a ‘1’ has to be written again. The measurement is
always started at the beginning of active video.
The vertical timing for the picture measurement is pro-
grammable, and may even be a single line. Also the sig-
nal bandwidth is switchable for the picture measure-
ment.
Two horizontal windows are available for the picture
measurement. The large window is active for the entire
active line. Tube measurement is always carried out with
the small window. Measurement windows for picture
and tube measurement are shown in Figure 2–12.
2.2.3. Average Beam Current Limiter
The average beam current limiter (BCL) uses the sense
input for the beam current measurement. The BCL uses
a different filter to average the beam current during the
active picture. The filter bandwidth is approx. 2 kHz. The
beam current limiter has an automatic offset adjustment
that is active two lines before the first cutoff measure-
ment line.
The beam current limiter function is located in the
VPC 32XX A. The data exchange between the VPC and
the DDP is done via a single-wire serial interface (ref.
section 2.3.5.).
The beam current limiter allows the setting of a threshold
current. If the beam current is above the threshold, the
excess current is low-pass filtered and used to attenuate
the RGB outputs by adjusting the white-drive multipliers
for the internal (digital) RGB signals, and the analog con-
trast multipliers for the analog RGB inputs, respectively.
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MICRONAS INTERMETALL