Micro Linear Corp. announced the industry's first integrated driver chip that filters and processes digital video for display. The new chip improves the quality of images coming from personal computers, DVD players, set-top boxes and game boxes. The ML6427 is used to filter and process digital video after it has been converted to analog by a digital-to-analog (DAC) converter. The chip accepts and outputs standard video formats including composite video, S-Video and RGB. The new device replaces four integrated circuits and thirty five discrete components.

The chip is an ideal choice as a driver for existing personal computer connectors such as VGA, or as a driver for the new EVC (Enhanced Video Connector) interface that will soon appear on personal computers, DVDs and set-top boxes. The new 35-pin EVC connector is expected to replace the standard VGA interface as a way to connect to video monitors, flat-panel displays and LCD screens. The ML6427 is also the ideal driver for the SCART connectors used on the outputs of set-top boxes in Europe.

According to Tony Ochoa, Product Marketing Manager, "We have packed into one device all the filtering and processing circuits needed between a digital video output and the standard display devices such as monitors, flat panel displays and LCD screens, and TV modulators. Furthermore, we made our chip easy to use by designing it as a high-level system building block with the industry standard interfaces including composite video, S-Video and RGB."

Key Functions

The ML6427 contains all the key functions needed for the complex process of preparing digital video for display. These function include four video filters, five video amplifiers, five multiplexers, a sync stripper and DC restoration clamp. The new chip guarantees a low differential gain (0.4 percent) and low differential phase (0.4 degrees) from the input of the filters to the output of the line drivers.

Typical Application

A typical example of preparing digital video for display begins with the ones and zeros of the video being converted to analog video via a DAC.

Then, the signal is fed into the ML6427 in either composite video, S-Video or RGB formats. The chip can simultaneously accept and process two (e.g., composite video, S-Video or RGB) video standards. The ML6427 automatically strips out the sync signal and routes it out of the chip so engineers can use it to synchronize signals on video connectors.

The sync signal is also routed back into the chip to control the DC clamp circuit which restores the DC level that determines which video signals are white.

The device is continuously filtering the two video inputs through a set of 4th-order Butterworth lowpass reconstruction filters with a cutoff frequency of 6.7Mhz. The chip also outputs the analog video through amplifiers that boost the signal with a gain of 2 and provide the current drive for 75ohm cables. This allows the chip to drive cables up to 300 feet. The ML6427 can simultaneously output two (e.g., composite video, S-Video or RGB) video formats.