STPC ATLAS
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Issue 1.1 - March 23, 2004
6.3.9. VGA INTERFACE
The STPC integrates a voltage reference and
video buffers. The amount of external devices is
then limited to the minimum as described in the
All the resistors and capacitors have to be as
close as possible to the STPC while the circuit
protector DALC112S1 must be close to the VGA
connector.
The DDC[1:0] lines, not represented here, have
also to be protected when they are used on the
VGA connector.
COL_SEL can be used when implementing the
Picture-In-Picture function outside the STPC, for
example when multiplexing an analog video
source. In that case, the CRTC of the STPC has to
be genlocked to this analog source.
DCLK is usually used by the TFT display which
has RGB inputs in order to synchronise the picture
at the level of the pixel.
When the VGA interface is not needed, the signals
R, G, B, HSYNC, VSYNC, COMP, RSET can be
left unconnected, VSS_DAC and VDD_DAC must
then be connected to GND.
Figure 6-15. Typical VGA implementation
143
VDD_DAC
COMP
VREF_DAC
RSET
VSS_DAC
2.5V
10nF
100nF 47uF
AGND
COL_SEL
DCLK
HSYNC
VSYNC
R
G
B
75 1%
DALC112S1
AGND
3.3V
100nF
1%