1997-02-27 , E/IC-462/530

Although the price of 15-inch and 17-inch computer monitors has fallen dramatically, their performance continues to increase, with digital controls and on-screen displays rapidly becoming standard features. Philips Semiconductors has introduced a unique I²C-bus video controller that increases the design FLEXibility and reduces the manufacturing costs of these colour monitors.

The TDA4885 Video Controller IC provides full I²C-bus control of brightness, contrast, white point, black level and on-screen display contrast, with automatic grey-scale tracking maintaining the correct colour balance when brightness or contrast settings are changed. Its pixel rate of 150 MHz and output rise time of 2.7 ns provide the ultra-sharp picture quality required for high-resolution graphics modes. In addition to being used in 15- and 17-inch monitors, the TDA4885 is also suitable for use in many 21-inch monitors and a wide range of TV sets.

This high-performance video controller not only provides I²C-bus control of the RGB channel gains for white-point adjustment, it also features a separate gain control input for each channel so that scan-dependent gain modulation can be applied. This allows picture enhancing features such as 'brightness uniformity' to be implemented. Its OSD insertion capabilities, with independent control of picture and OSD contrast, suit it for multi-media applications.

"The TDA4885's comprehensive I²C-bus control features not only give monitors sophisticated user controls", said Product Marketing Manager Alois Kliner, "they also mean that most of the circuit alignment required during manufacture of the monitors can be fully automated."

The TDA4885's RGB inputs accept 0.7 V video signals and include all the necessary blanking, clamping and clipping circuits. Its outputs provide feedback paths for both DC coupled and AC coupled CRT cathodes, and allow I²C-bus control of black-level or pedestal (ultra-black level) clamping. The device can therefore be used with a wide range of CRT drive circuits. It works particularly well when combined with one of the deflection controllers from Philips' TDA485x family of deflection controllers, or in TV sets with the company's recently introduced TDA9152 programmable deflection controller.

Packaged in a 32-pin SDIP, the TDA4885 sells for around US$ 1.60 in high volume. Production quantities can be delivered 5 weeks after receipt of order.