Analog Devices AD721JP, AD720JP Datasheet

a

SYNC

DECODER

BURST

C-SYNC

4FSC

ENCD

RED

GREEN

BLUE

QUADRATURE

DECODER

DELAYED C-SYNC

SC 90

°

SC 0

°

CLOCK

AT 8FSC

DC

RESTORE

AND C-SYNC

INSERTION

5MHz

2-POLE

LP POST-

FILTER

COMPOSITE OUTPUT*

–0.572V TO 2V NTSC
–0.6V TO 2V PAL

LUMINANCE OUTPUT*

–0.572V TO 1.43V NTSC
–0.6V TO 1.4V PAL

CHROMINANCE OUTPUT*

572mVp-p NTSC
600mVp-p PAL

NTSC/PAL

C-SYNC

DELAY

±180

°

(PAL ONLY)

RGB-TO-YUV

ENCODING

MATRIX

BURST

Y

U

V

SC 90

°

/270

°

5MHz

4-POLE LP

PRE-FILTER

1.2MHz
4-POLE

LPF

1.2MHz
4-POLE

LPF

SAMPLED-

DATA

DELAY LINE

∑

3.6MHz (NTSC)

4.4MHz (PAL)
3-POLE LPF

∑

X2

X2

X2

POWER AND GROUNDS

+5V

AGND
DGND

LOGIC

ANALOG
ANALOG ONLY
ANALOG

LOGIC

+5V
–5V

*NOTE:
THE LUMINANCE, COMPOSITE, AND CHROMINANCE
OUTPUTS ARE AT TWICE NORMAL LEVELS FOR
DRIVING 75Ω REVERSE-TERMINATED LINES.

ASNC

NTSC/PAL

BALANCED

MODULATORS

NTSC/

PAL

X2

X2

X2

ROUT

1.5Vp-p

GOUT

1.5Vp-p

BOUT

1.5Vp-p

AD721

(ONLY)

NTSC/PAL

RGB to NTSC/PAL Encoders

AD720/AD721

FEATURES
Composite Video Output
Chrominance and Luminance (S-Video) Outputs
No External Filters or Delay Lines Required
Drives 75 Ω Reverse-Terminated Loads
Compact 28-Pin PLCC
Logic Selectable NTSC or PAL Encoding Modes
Automatically Selects Proper Chrominance Filter

Cutoff Frequency for Encoding Standard

Logic Selectable Encode or Power-Down Mode (AD720

Only)
Logic Selectable Encode or Bypass Mode (AD721 Only)
Low Power: 200 mW typical

APPLICATIONS
RGB to NTSC or PAL Encoding

Drive RGB Signals into 75 Ω Load (AD721 Only)

PRODUCT DESCRIPTION

The AD720 and AD721 RGB to NTSC/PAL Encoders convert
red, green and blue color component signals into their corre­sponding luminance (baseband amplitude) and chrominance

FUNCTIONAL BLOCK DIAGRAM

(subcarrier amplitude and phase) signals in accordance with
either NTSC or PAL standards. These two outputs are also
combined to provide a composite video output. All three out­puts are available separately at voltages of twice the standard
signal levels as required for driving 75 Ω reverse terminated
cables. The AD721 also features a bypass mode, in which the
RGB inputs may bypass the encoder section of the IC via three
gain-of-two amplifiers suitable for driving 75Ω reverse termi­nated cables.

The AD720 and AD721 provide a complete, fully calibrated
function, requiring only termination resistors, bypass capacitors,
a clock input at four times the subcarrier frequency, and a com­posite sync pulse. There are two control inputs: one input
selects the TV standard (NTSC/PAL) and the other (ENCD)
powers down most sections of the chip when the encoding func­tion is not in use (AD720) or activates the triple bypass buffer to
drive the RGB signals when RGB encoding is not required
(AD721). All logical inputs are CMOS compatible. The chip
operates from ± 5 V supplies.

(continued on page 5)

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.

One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: [phone] Fax: [phone]

AD720/AD721–SPECIFICATIONS

(TA = +25°C and supplies = ±5 V unless otherwise noted)

Parameter Conditions Min Typ Max Unit

SIGNAL INPUTS (RDIN, GRIN, BLIN)

Input Amplitude NTSC 714 mV

PAL 700 mV

Input Resistances

1

RDIN with Respect to AGND 2.3 kΩ
GRIN with Respect to AGND 4.2 kΩ
BLIN with Respect to AGND 4.2 kΩ

Input Capacitance 5pF

LOGIC INPUTS (C-SYNC, 4FSC, ENCD, NTSC)

Logic LO Input Voltage 1 V
Logic HI Input Voltage 4 V
Logic LO Input Current (DC) <1 µA
Logic HI Input Current (DC) <1 µA

BYPASS AMPLIFIERS (AD721 Only)

Gain Error Nominal Gain of ×2

2

–5 +5 %
Small Signal –3 dB Bandwidth 100 MHz
Output Offset Voltage (Active State) –50 +50 mV
Output Voltage (Inactive State) –50 +50 mV

VIDEO OUTPUTS3 (LUMA, CRMA, CMPS)

Luminance (LUMA) Output

Bandwidth 5 MHz
Gain Error –5 ±1 +5 %
Linearity ±0.1 %
Sync Level NTSC 252 286 320 mV

PAL 300 mV

Chrominance (CRMA) Output

Bandwidth NTSC 3.6 MHz

PAL 4.4 MHz

Color Burst Amplitude NTSC 257 286 315 mV p-p

PAL 300 mV p-p
Absolute Gain Error –15 ±5 +15 %
Absolute Phase Error ±3 Degrees

Chroma/Luma Time Alignment

4

NTSC –170 ns

Composite Output

Absolute Gain Error –5 ±1 +5 %
Differential Gain With Respect to Chroma Channel 0.1 %

Differential Phase With Respect to Chroma Channel 0.1 Degrees
Output Offset Voltage Chroma, Luma, or Composite Outputs 50 100 mV
Chroma Feedthrough Monochrome Input 20 55 mV p-p

POWER SUPPLIES (APOS, DPOS, VNEG)

Recommended Supply Range Dual Supply ±4.75 ±5.25 V
Full Output Current

5

–5 V Supply 35 mA
+5 V Supply 67 mA

Zero Signal Quiescent Current –5 V Supply 10 20 35 mA

+5 V Supply 10 20 35 mA
Bypass Mode Quiescent Current –5 V Supply 14 20 mA
(AD721 Only) +5 V Supply 14 20 mA

NOTES

1

Input scaling resistors provide best scaling accuracy when source resistance is 37.5 Ω (75 Ω reverse-terminated input).

2

Required for driving a 75 Ω double reverse terminated load.

3

All outputs are measured at a reverse-terminated load; voltages at IC pins are twice those specified here.

4

This is a predistortion (per FCC specifications) that compensates for the chroma/luma delay in the low-pass filter that separates the luminance and chrominance

signals in a television receiver.

5

CRMA, LUMA, and CMPS outputs are all connected to 75 Ω reverse-terminated loads; full-white signal for entire field.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min
and max specifications are guaranteed, although only those shown in boldface are tested on all production units.
Specifications subject to change without notice.

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REV. 0

AD720/AD721

WARNING!

ESD SENSITIVE DEVICE

ABSOLUTE MAXIMUM RATINGS*

PIN DESCRIPTIONS

Supply Voltage ±VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±6V

Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . . .600 mW

Operating Temperature Range . . . . . . . . . . . . . . 0°C to +70°C

Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C

Lead Temperature, Soldering 60sec . . . . . . . . . . . . . . +300°C

NOTE
*Stresses above those listed under “Absolute Maximum Ratings” may cause

permanent damage to the device. This is a stress rating only, and 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 rating conditions for extended periods
may affect device reliability.

Thermal characteristics: 28-pin plastic package: θJA = 100°C.

ORDERING GUIDE

Temperature Package

Model Range Package Option

AD720JP 0°C to +70°C 28-Pin PLCC P-28A
AD721JP 0°C to +70°C 28-Pin PLCC P-28A

PIN CONNECTIONS

28-Lead Plastic Leaded Chip Carrier (PLCC) Package

P-28A

APOS

APOS

VNEG

BOUT (NC)

261

VNEG

LUMA

25

DGND

24

SYNC

23

DPOS

22

ASNC

21

DPOS
4FSC

20
19

DGND

AGND

5

ENCD

RDIN

6
7

AGND

GRIN

8

AGND

9

10

BLIN

STND

11

NOTE:
CONNECTIONS IN ( ) PERTAIN ONLY TO AD720

RGB TO NTSC/PAL

12

13 14 15 16 17 18

AGND

GOUT (NC)

APOS (NC)

ROUT (NC)

234

AD720/AD721

ENCODER

APOS

CMPS

CRMA

28 27

Pin Mnemonic* Description*

1 (NC) GOUT (No Connection) Green Bypass Buffer
2 (NC) APOS (No Connection) Analog Positive Supply; +5V ± 5%
3 (NC) ROUT (No Connection) Red Bypass Buffer
4 AGND Analog Ground Connection
5 ENCD A Logical High Enables the NTSC/PAL Encode

Mode (A Logical Low Powers Down the Chip)
A Logical Low Enables the RGB Bypass Mode

6 RDIN Red Component Video Input

0 mV to 714 mV for NTSC

0 mV to 700 mV for PAL
7 AGND Analog Ground Connection
8 GRIN Green Component Video Input

0 mV to 714 mV for NTSC

0 mV to 700 mV for PAL
9 AGND Analog Ground Connection

10 BLIN Blue Component Video Input

0 mV to 714 mV for NTSC

0 mV to 700 mV for PAL

11 STND A Logical High Input Selects NTSC Encoding

A Logical Low Input Selects PAL Encoding

CMOS Logic Levels

12 AGND Analog Ground Connection
13 CRMA Chrominance Output; Subcarrier Only**

572 mV Peak-to-Peak for NTSC

600 mV Peak-to-Peak for PAL

14 APOS Analog Positive Supply; +5 V ± 5%
15 CMPS Composite Video Output**

–572 mV to 2 V for NTSC

–600 mV to 2 V for PAL

16 APOS Analog Positive Supply; +5 V ± 5%
17 LUMA Luminance Plus SYNC Output**

–572 mV to 1.43 V for NTSC

–600 mV to 1.4 V for PAL

18 VNEG System Negative Supply; –5V ± 5%
19 DGND Digital Ground Connection
20 4FSC Clock Input at Four Times the Subcarrier Frequency

14.318 180 MHz for NTSC

17.734 480 MHz for PAL

CMOS Logic Levels

21 DPOS Digital Positive Supply; +5V ± 5%
22 ASNC A Logical High Input Resets the Subcarrier Phase

Every Frame

A Logical Low Input Resets the Subcarrier Phase

Every Fourth Frame

CMOS Logic Levels

23 DPOS Digital Positive Supply; +5V ± 5%
24 SYNC Input for Composite Television

Synchronization Pulses

Negative Sync Pulses

CMOS Logic Levels

25 DGND Digital Ground Connections (One of Two)
26 VNEG System Negative Supply; –5V ± 5%
27 (NC) BOUT (No Connection) Blue Bypass Buffer
28 APOS Analog Positive Supply; +5 V ± 5%

*( ) pertain only to AD720.

**The luminance, chrominance, and composite outputs are at twice normal

levels for driving 75 Ω reverse-terminated lines.

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 AD720/AD721 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–