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


Application

RGB to NTSC or PAL Encoding
Drive RGB Signals into 75 Ω Load (AD721 Only)


Pinout




Specifications

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 60 sec  . . . . . . . . . . . . . . +300°C


Description

The AD720 and AD721 RGB to NTSC/PAL Encoders convert red, green and blue color component signals into their corre- sponding luminance (baseband amplitude) and chrominance (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 75 Ω 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.