
DAC 1
DAC 2
Video
encoder
TVOUT
buffer
TVOUT
buffer
TV DETECT
VREF
10
10
DAC stage with amplifier
cvideo1_vfb
cvideo1_rset
Device
TVDET
GPIO2
TVINT
vdda_dac
vssa_dac
cvideo1_out
dss-082
cvideo2_vfb
cvideo2_out
Public Version
www.ti.com
Display Subsystem Functional Description
Figure 7-109. Video DAC Stage Architecture
The display subsystem provides the necessary control signals to interface the memory frame buffer
directly to external displays (TV sets). Two (one per channel) 10-bit current steering AVDACs are used to
generate the video analog signal:
•
AVDAC1: Carries either the CVBS (composite) or S-Video Luma (Y) analog TV outputs; it provides
also the TV detection/disconnection and power-down mode features.
•
AVDAC2 : Carries only the S-Video Chroma (C) analog TV output.
The device system control module provides two dedicated AVDAC registers,
CONTROL.CONTROL_AVDAC1 and CONTROL.CONTROL_AVDAC2, to configure the respective
channels through the following bit field:
•
CONTROL.CONTROL_AVDACx
[20:16]
AVDACx_COMP_EN:
Allows
direct
control
over
the
configuration of the analog TV output. See
, Video Encoder Basic
Programming Model, and
, System Control Module.
Table 7-45. Analog TV Output Control
Register CONTROL.CONTROL_AVDACx [x=1, 2] Description
[19] AVDACx_COMP_EN
Single or dual channel operation
0: Single channel (default)
1: Dual channel
[18] AVDACx_COMP_EN
Channel role
0: Luma video channel (dual-channel configuration) or Composite video
channel (single-channel configuration) (default)
1:Chroma video channel (dual-channel configuration)
1697
SWPU177N – December 2009 – Revised November 2010
Display Subsystem
Copyright © 2009–2010, Texas Instruments Incorporated