Analog Devices AD723 Datasheet

2.7 V to 5.5 V RGB-to-NTSC/PAL Encoder with

a

Load Detect and Input Termination Switch

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,

AD723

or combined for composite video (CV). All outputs are avail­able 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 applica­tions 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. Under­scan 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 infor­mation 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.

FUNCTIONAL BLOCK DIAGRAM

TRIPLE INPUT
TERMINATION

RIN

RT

GIN

GT

BIN

BT

TERM

4FSC

HSYNC

VSYNC

GND

GND

GND

DC

CLAMP

DC

CLAMP

DC

CLAMP

RGB-TO-YUV

ENCODING

MATRIX

Y

U

V

QUADRATURE

DECODER

SYNC

SEPARATOR

4-POLE

LPF

CSYNC

4-POLE

LPF

BURST

4-POLE

LPF

BURST

FSC

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.

CURRENT OUTPUT DRIVERS

8FSC CLK

4-POLE

LPF

4-POLE

LPF

BALANCED

MODULATORS

SIN COS

LUMA

DELAY LINE

AD723

BURST

CSYNC

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 2000

STND

WITH SMART LOAD DETECT

LUMINANCE

LUMA

TRAP

TV DETECTCE

COMPOSITE

CHROMINANCE

GAIN SET

RESISTORS

Y TRAP

CVSET

Y

CV

C

YSET

CSET

AD723–SPECIFICATIONS

(VS = 3, TA = 25ⴗC, using 4FSC synchronous clock unless otherwise noted. Signal

inputs terminated with 75 ⍀. Outputs configured in active termination mode, 75 ⍀ external load.)

Parameter Conditions Min Typ Max Unit

SIGNAL INPUTS (RIN, GIN, BIN)

Input Amplitude Full-Scale 714 mV p-p
Clamp Level 400 mV
Input Resistance RIN, GIN, BIN 1 MΩ
Input Capacitance 5pF

TERMINATION SWITCH CHARACTERISTICS
(RT, GT, BT)

Input Capacitance VIN = 0 V 6 pF
Switch On Resistance VIN = 0 V 5.2 Ω

LOGIC INPUTS
(STND, SA, CE, TERM, SYNC, 4FSC)

Logic LO Input Voltage 1V
Logic HI Input Voltage 2 V
Logic LO Input Current (DC) 0.015 0.70 µA
Logic HI Input Current (DC) 0.020 0.70 µA

VIDEO OUTPUTS

Luminance (Y)

–3 dB Bandwidth, NTSC Mode NTSC 4.7 MHz

PAL 6.1 MHz

Gain Error Direct Input Termination –6.25 –2.5 +1.5 %

Switch Input Termination –0.7 %
Gain Nonlinearity 0.3 %
Sync Amplitude NTSC 218 262 362 mV

PAL 230 277 385 mV
DC Black Level NTSC 450 mV

PAL 450 mV

Chrominance (C)

Burst Amplitude NTSC 185 250 315 mV p-p

Chroma Level Error
Chroma Phase Error

1

2

PAL 190 251 320 mV p-p

Switch Input Termination 4 %

± 3 Degree

Color Burst Width NTSC 2.51 µs

PAL 2.26 µs
Chroma/Luma Time Alignment 19 ns
Chroma Feedthrough RGB = 0 10.5 40 mV p-p
DC Black Level NTSC 661 mV

PAL 608 mV

Composite (CV)

Gain Error Direct Input Termination –6.8 –2.4 +2.5 %

Switch Input Termination –0.75 %
Gain Error wrt LUMA Direct Input Termination 0.14 %
Differential Gain Error wrt CRMA 0.9 %
Differential Phase Error wrt CRMA 0.95 Degree
DC Black Level NTSC 456 mV

PAL 440 mV

Luminance Trap (YTRAP) Output Resistance 1.4 kΩ

LOGIC OUTPUT (TVDET)

LO Output Voltage 0.02 V
HI Output Voltage 2.98 V

POWER SUPPLIES

Operating Voltage Range Single Supply 2.7 5.5 V
Current Consumption

Quiescent No External Loads Present 16 19 mA
Composite Output Connected

S-Video Output Connected

3

3

75 Ω Load, Active Termination, 30 39 mA

S-Video Inactive

75 Ω Load, Active Termination, 41 49 mA

Composite Output Inactive

Power-Down Current 0.09 0.7 µA

NOTES

1

Difference between ideal and actual color-bar subcarrier amplitudes.

2

Difference between ideal and actual color-bar subcarrier phase.

3

Current consumption is larger in standard termination mode. Current values shown for 50% avera ge picture level. Larger current consumption possible for other levels.

Specifications subject to change without notice.

–2–

REV. 0

AD723

WARNING!

ESD SENSITIVE DEVICE

TOP VIEW

(Not to Scale)

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

AD723

DGND

DVDD

TGND

BT

GT

RT

AGND

STND

SA

CE

TERM

BIN

GIN

RIN

HSYNC

VSYNC

4FSC

TVDET

CVSET

CV

YTRAP

AGND

YSET

Y

AVDD1

AVDD

C

CSET

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage, AVDD to AGND . . . . . . . . . . . . . . . . . . . 6 V

Supply Voltage, DVDD to DGND . . . . . . . . . . . . . . . . . . 6 V

AVDD to DVDD . . . . . . . . . . . . . . . . . . . . . –0.3 V to +0.3 V

AGND to DGND . . . . . . . . . . . . . . . . . . . . . –0.3 V to +0.3 V

Inputs . . . . . . . . . . . . . . . . . . DGND – 0.3 to DVDD + 0.3 V

Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . 800 mW

Operating Temperature Range . . . . . . . . . . . –40°C to +85°C

Storage Temperature Range . . . . . . . . . . . . –65°C to +125°C

Lead Temperature Range (Soldering 60 sec) . . . . . . . . . 300°C

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

THERMAL CHARACTERISTICS

28-lead TSSOP package: θJA = 67.7°C/W.
Thermal Resistance measured on SEMI standard 4-layer board.

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

AD723ARU –40°C to +85°C 28-Lead TSSOP RU-28
AD723ARU-REEL –40°C to +85°C 28-Lead TSSOP RU-28
AD723-EVAL Evaluation Board

PIN CONFIGURATION

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the AD723 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions
are recommended to avoid performance degradation or loss of functionality.

REV. 0

–3–

AD723

PIN FUNCTION DESCRIPTIONS

Pin Mnemonic Description Equivalent Circuit

1 STND Encoding Standard Pin. A Logic HIGH signal is used for NTSC encoding, a Logic LOW Circuit A

signal signifies PAL.

2 SA When SA is high, phase alternation accompanies NTSC bandwidths and timing for Circuit A

support of PAL (M) and “combination N” standards used in South America.

3 CE Chip Enable. A Logic HIGH input enables the encode function. A Logic LOW input Circuit A

powers down the chip when not in use. Requires active HSYNC signal to activate.
Can be raised briefly to perform power-down load check.

4 TERM Terminate. A Logic HIGH enables terminate function. RT, GT, and BT terminals are Circuit A

tied to the termination ground, TGND. A Logic Low leaves these terminals floating.
5 RIN Red Component Video Input. 0 mV to 714 mV ac-coupled. Circuit B
6 GIN Green Component Video Input. 0 mV to 714 mV ac-coupled. Circuit B
7 BIN Blue Component Video Input. 0 mV to 714 mV ac-coupled. Circuit B
8 AGND Analog Ground Connection. (Main Ground Connection.)
9 RT Input Terminal for RED Termination Switch. Can be left unconnected when switchable Circuit F

input termination option is not used.
10 GT Input Terminal for GREEN Termination Switch. Can be left unconnected when switchable Circuit F

input termination option is not used.
11 BT Input Terminal for BLUE Termination Switch. Can be left unconnected when switchable Circuit F

input termination option is not used.
12 TGND Termination Switch Ground Connection.
13 DVDD Digital Positive Supply Connection.
14 DGND Digital Ground Connection.
15 HSYNC Horizontal Sync Signal (or CSYNC signal). Circuit A
16 VSYNC Vertical Sync Signal. Circuit A
17 4FSC 4FSC Clock Input. For NTSC: 14.318 180 MHz, for PAL: 17.734 475 MHz. Circuit A
18 TVDET Output Flag for TV Presence Detection. LOW signal signifies no TV present. Circuit E
19 CVSET Composite Video Gain Setting Resistor. Circuit C
20 CV Composite Video Output. Circuit C
21 YTRAP Luminance Trap Filter Tap. Attach L-C resonant network to reduce cross-color artifacts. Circuit D
22 AVDD Analog Positive Supply Connection.
23 C Chrominance Output. Circuit C
24 CSET Chrominance Gain Setting Resistor. Circuit C
25 AVDD1 Analog Positive Supply Connection.
26 Y Luminance Output (with CSYNC). Circuit C
27 YSET Luminance Gain Setting Resistor. Circuit C
28 AGND Analog Ground Connection.

APOS

POS

1
2
3

4
15
16
17

Circuit A Circuit B Circuit C Circuit D

POS

DPOS

5
6
7

DGND

DPOS

1k⍀

DPOS

DGNDDGND

18

9
10
11

APOS

AGND

TGND

19
20
23
24
26
27

APOS

1k⍀

Circuit E Circuit F

Figure 1. Equivalent Circuits

–4–

APOS

21

AGNDAGND

REV. 0

FSC

(3.579545MHz

OR

4.433618MHz)
OSCILLATOR

TEKTRONIX

TG2000
SIGNAL

GENERATION

PLATFORM

GENLOCK

Typical Performance Characteristics–

3V

COMPOSITE

FSC

RGB

SYNC

3

HP3314A

ⴛ 4 PLL

75⍀

AD723

RGB-TO­NTSC/PAL
ENCODER

TPC 1. Evaluation Setup

4FSC

COMPOSITE

VIDEO

SONY

MONITOR

MODEL

PVM-1354Q

75⍀

TEKTRONIX

VM700A

WAVEFORM

MONITOR

AD723

1.0

0.5

VOLTS

0.0

APL = 51.2%
525 LINE NTSC NO FILTERING

SLOW CLAMP TO 0.0V @ 6.63␮s

–0.5

06010 20 30 40 50

TPC 2. 100% Color Bars, NTSC

NOISE REDUCTION: 15.05dB
APL = 50.7%

1.0

100

0.5

50

IRE

0

–50

µs

VOLTS

0.0

APL = 51.2%
625 LINE PAL NO FILTERING

SLOW CLAMP TO 0.00V @ 6.72␮s

–0.5

06010 20 30 40 50

␮s

TPC 4. 100% Color Bars, PAL

SYSTEM LINE L147 F1
ANGLE (DEG) 0.0
GAIN ⴛ 0.750 –2.499dB
525 LINE NTSC
BURST FROM SOURCE

NOISE REDUCTION: 15.05dB
APL = 51.0%

SYSTEM LINE L29
ANGLE (DEG) 0.0
GAIN ⴛ 0.750 –2.499dB
625 LINE PAL
BURST FROM SOURCE
DISPLAY +V AND –V

SETUP 7.5%

TPC 3. 100% Color Bars on Vector Scope, NTSC

REV. 0

SOUND IN SYNC OFF

TPC 5. 100% Color Bars on Vector Scope, PAL

–5–

AD723

1.0
APL = 46.6%

525 LINE NTSC NO FILTERING
SLOW CLAMP TO 0.00V @ 6.63␮s

0.5

VOLTS

0.0

–0.5

06010 20 30 40 50

␮s

TPC 6. Modulated Pulse and Bar, NTSC

100

50

0

–50

IRE

VOLTS

–0.5

1.0
APL = 34.8%

625 LINE PAL NO FILTERING
SLOW CLAMP TO 0.00V @ 6.72 ␮s

0.5

0.0

06010 20 30 40 50

␮s

TPC 8. Modulated Pulse and Bar, PAL

200mV 1␮s

TPC 7. Zoom on Modulated Pulse, NTSC

200mV 1␮s

TPC 9. Zoom on Modulated Pulse, PAL

–6–

REV. 0