AD723ARUZ Datasheet, PDF (1/20 Pages) Analog Devices – 2.7 V to 5.5 V RGB-to-NTSC/PAL Encoder with Load Detect and Input Termination Switch

a 2.7 V to 5.5 V RGB-to-NTSC/PAL Encoder with
Load Detect and Input Termination Switch
AD723
FEATURES
Low Cost, Fully Integrated Solution for NTSC/PAL
Composite and Y/C (S-Video) Outputs
Current Output Drives 75 ⍀ Loads
DC-Coupled: Supports TV Load Detect
No Large AC-Coupling Capacitors at Output
Self-Power-Down of Unloaded Output Drivers
Triple Switch to Enable RGB Termination
Integrated Delay Line and Auto-Tuned Filters
Y-Trap to Eliminate Cross Color Artifacts
3 V Supply Operation: Low Power
< 100 mW: Composite Active (Typical)
< 150 mW: S-Video Active (Typical)
<1 ␮A: Power-Down Current
APPLICATIONS
TV Out for Personal Computers/Laptops
Digital Cameras
Set-Top Boxes
Video Games
Internet Appliances
PRODUCT DESCRIPTION
The AD723 is a low cost RGB-to-NTSC/PAL encoder that
converts analog red, green, and blue color component signals
into their corresponding luminance and chrominance signals for
display on an NTSC or PAL television. Luminance (Y) and
Chrominance (C) signals are available individually for S-video,
or combined for composite video (CV). All outputs are avail-
able separately and optimized for driving 75 Ω loads. Active
termination is used for lower power consumption.
A smart load detect feature powers down unused outputs and
can be used to monitor the continuing presence or absence of
an external TV. This enables plug-and-play operation. In addition,
a logic controlled triple switch at the input solves the applica-
tions problem of differing load conditions when an RGB monitor
is disconnected. When an RGB monitor is not present, the R,
G, and B terminations are enabled by the user. This solution
ensures no loss of video bandwidth when the RGB monitor is
in operation.
In PC applications, flicker filter support is provided by the
graphics controller, which has direct access to memory. Under-
scan compensation, necessary for uses other than video or
DVD, is supported through choice of RGB output clocks and
sync intervals.
An optional luminance trap (YTRAP) provides a means of
reducing cross color artifacts due to subcarrier frequency infor-
mation in the Y signal.
The AD723 is available in a 28-lead TSSOP package and is
capable of operation from supplies of 2.7 V to 5.5 V.
TRIPLE INPUT
TERMINATION
RIN
RT
GND
DC
CLAMP
GIN
GT
GND
DC
CLAMP
BIN
BT
GND
TERM
4FSC
HSYNC
VSYNC
DC
CLAMP
FUNCTIONAL BLOCK DIAGRAM
Y _4-POLE
LPF
RGB-TO-YUV
ENCODING
MATRIX
CSYNC
U _4-POLE
LPF
BURST
V _4-POLE
LPF
BURST
SIN
QUADRATURE
DECODER
SYNC
SEPARATOR
FSC
BURST
CSYNC
8FSC CLK
LUMA
DELAY LINE
BALANCED
MODULATORS
CURRENT OUTPUT DRIVERS
WITH SMART LOAD DETECT
4-POLE
LPF
LUMA
TRAP
LUMINANCE
Y
Y TRAP
COMPOSITE
CV
4-POLE
LPF
CHROMINANCE
C
COS
AD723
GAIN SET
RESISTORS
YSET
CSET
CVSET
STND
CE
TV DETECT
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
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© Analog Devices, Inc., 2000