SDA9401 Datasheet, PDF (33/69 Pages) List of Unclassifed Manufacturers – Scan Rate Converter using Embedded DRAM Technology Units

SDA 9401
mode. The figure below shows the two cases. If RMODE=1, then for each incoming V-sync signal
VIN an outgoing V-sync signal VOUT has to be generated (50 Hz interlaced to 50 Hz progressive
scan rate conversion). If RMODE=0, then during one incoming V-Sync signal, two VOUT pulses
have to be generated (50 Hz interlaced to 100 Hz interlaced scan rate conversion).
Examples for VOUT generation depending on parameter RMODE
VIN
VOUT
RMODE=1
VOUT
RMODE=0
The VOUT signal has a delay of two CLKOUT clocks to the HOUT signal or in case of interlaced a
delay of a half line plus two CLKOUT clocks.
Output write parameter
Parameter
VOUTFR
1: freerun
0: locked
mode
RMODE
1: progressive
0: interlaced
Subaddress
14h
14h
Description
VOUT generator mode select
Raster mode
Switching from H-and-V-freerunning to H-and-V-locked mode
In H-and-V-freerunning mode, generally, the phase of the generated synchronization raster has no
correlation to the input raster. A hard switch from the H-and-V-freerunning mode to the H-and-V-
locked mode therefore would cause visible synchronization artefacts. To avoid these problems the
SDA 9400 enlarges the line and the field lengths of the output sync signals HOUT and VOUT in a
defined procedure to enable an unvisible synchronization of the freerunning output to the input.
For vertical synchronization the maximum synchronization time is 260 ms for interlaced and 520 ms
for progressive display modes. Horizontal synchronization is performed in a maximum time of 50
ms. To get the best performance it is recommended to change at first the vertical and after the
mentioned delay times the horizontal mode from free running to locked.
Micronas
33
Preliminary Data Sheet