SDA9220-5 Datasheet, PDF (3/42 Pages) Siemens Semiconductor Group – Memory Sync Controller III

SDA 9220-5
Detailed Circuit Description
Picture Formats
The MSC forms part of a digital television system with line-locked scanning frequency. The nominal
word rate is 13.5 MHz for luminance and 3.375 MHz for each of the U and V color components. The
active region of a TV line is identified by the high time interval of BLN. It comprises 720 pixels for
luminance and 180 pixels each for U and V and is stored in its entirety. In the 50-Hz standard a field
consists of 287.5 lines and in the 60-Hz standard of 243.5 lines.
288 lines are stored in the 50-Hz standard (lines 23-310 of the first field, lines 336-623 of the second
field) and 243 lines in the 60-Hz standard (lines 17-259 of the first field, lines 280-522 of the second
field), (figure 1). In the 9-image mode a field without a frame consists of 208 pixels per line for
luminance and 2 x 52 pixels per line for chrominance, with four pixels being lost for luminance and
2 x 1 for chrominance with memory or display frames. The number of lines without a frame is 84 for
the 50-Hz standard and 71 for the 60-Hz standard. Two lines less are displayed with a frame
(figures 2 and 3).
In the picture-in-still (PIS) and still-in-picture (SIP) modes a field without a frame or having a display
frame is of the same size as a 9-image window. With the memory frame, however, eight pixels are
lost for luminance and 2 x 2 for chrominance (figure 4).
For generating the windows in the modes 9-image display, PIS and SIP the picture data are filtered
horizontally and vertically in the picture processor and reduced by a factor of three.
In the zoom mode a segment of the stored picture is enlarged by a factor of two by displaying each
pixel twice as long and each line twice. The position of this picture segment is selectable.
Eight vertical and twelve horizontal positions can be set by the I²C Bus (figure 5).
Random Interlace
The phase of VS relative to HS and the active picture content is measured at the input. At the output
VS2 is generated in the same phase relation to HS2 and the picture content. Despite the random
interlacing this means that standard picture conversion is possible without any visible interference.
Display Raster
There are three ways of displaying the field sequence: one is without interlace and two are with
interlace, i.e. with a 50-Hz or 60-Hz interlace frequency or a 100-Hz or 120-Hz interlace frequency
respectively. In what follows these are referred to symbolically as αααα, ααββ or βαβα. They are
produced by a suitable sequence of the vertical sync pulses VS2 for the standard-converted video
signal. The symbols α_n, β_n denote the vertical sync phases of the pulses (VS, VS2) referred to the
horizontal blanking signals (BLN, BLN2), i.e. αn when the positive vertical sync edge falls within one
blanking half cycle and β_n when it falls within the complementary blanking half cycle.
Normally the input signal will be as follows: (α_n–1, β_n–1) (α_n, β_n) (α_n+1, β_n+1) with α_n and β_n virtually
constant. Figures 15, 16, 17, 18 and 19 show the sequence obtained for output signal VS2 when
using one of the three operating modes.
Semiconductor Group
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