AD723:  2.7 V to 5.5 V RGB-to-NTSC/PAL Encoder with Load Detect and Input Termination Switch

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 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.