A video solution for CRT displays

National Semiconductor has introduced three new CMOS video preamplifiers with internal on screen display (OSD) for CRT monitors. The I2C compatible preamplifiers offer CRT manufacturers a portfolio of neckboard solutions for any size and resolution monitor, from 14 in. to 21in. with a choice of OSD support.

The first in the line up, LM1237, is a 150MHz, I2C compatible CMOS RGB video preamplifier with internal 254 character OSD. It contains 192 two-colour and 64 four-colour characters with an option to program up to 318 two-colour characters. The mask programmable characters are defined in a 12×18 (WxH) matrix and displayed in a 512 character page RAM. The LM1237 controls all the parameters necessary to directly setup and adjust the gain and contrast of a CRT display. Brightness and bias can be controlled through the DAC outputs, which are well matched to National’s LM2480 and LM2479 integrated bias clamp ICs.

National’s LM1247 provides the same features and bandwidth of the LM1237, but instead offers a 512 character OSD with 128 four-colour characters that can be used to extend the OSD capacity to as many as 640 two-colour characters.

National’s LM1238 is a 110MHz, I2C compatible CMOS RGB video preamplifier that introduces a new concept in OSD. Pin-to-pin compatible with the LM1237 and LM1247, the LM1238 contains an entirely language independent, icon-based OSD. This graphical OSD eliminates the majority of the development time and firmware needed to design and program OSD pages. A standard set of icons is programmed into the LM1238 ROM and the manufacturer simply addresses the relevant adjustment icon to display an OSD page. The entire sequence can be completed with just two bytes of information.

National’s LM1237 and LM1238 preamplifiers, both in 24-pin DIP, are available now. In 1,000 unit quantities, the LM1237 costs $3.50 and the LM1238 costs $1.75. The LM1247, also in a 24-pin DIP, is sampling now and will be released to production in August. The LM1247 will cost $4.00 in 1,000 unit quantity.