"Convergence" Gains New Meaning with Chips from Texas Instruments

If there's no computer in your entertainment system—or no entertainment in your computer—there probably will be soon. Texas Instruments has announced two new digital-to-analog converters (DACs) that accept and output all available video and PC graphics formats—including HDTV signals. The new chips may make "all-formats video" economically viable for many manufacturers.

On May 9, the Dallas-based technology giant introduced the new THS8135, a 10-bit video DAC, and the THS8136, an 8-bit DAC. The devices are said to be the first that can be "software-configured to generate standard 700mV component video output from either ITU-R.BT601 (SDTV) or SMPTE274M/296M (HDTV) YCbCr sampled signals, as well as from RGB sampled (VESA) PC graphics signals." Both chips have higher sampling speeds and lower power consumption than any others on the market, and will allow consumer electronics manufacturers to include high-resolution PC graphics output—in addition to component and composite video outputs—at no additional cost in the next generation of infotainment products. Among the products to benefit are "DVD players, digital TV and HDTV receivers, multimedia PC cards, video game consoles, Web- enabled TVs, and professional broadcast and video post-production equipment."

The THS8135 and THS8136 support both color systems (YCbCr and RGB) and "include an optional scaling/clipping function on the digital input to support either full-range sampled or reduced-range (ITU-R.BT601) sampled signals," according to a company press release. "The clipping function reduces filtering artifacts in the resulting analog signal, and the input code scaling guarantees compliant analog output ranges for both PC graphics and SDTV/HDTV component video, with no need for any board hardware changes when switching between PC and video modes," the announcement explained.

Versatility is the name of the game with TI's new chips. A "generic DAC mode" allows either chip to work with an external composite (NTSC/PAL/SECAM) video encoder outputing digital composite video, for final D/A conversion of the signal. Software switches the output from a 700mVpp component DAC mode to a 1.3Vpp-compliant DAC mode, as required for composite video. TI claims that the DACs offer "excellent channel matching specifications, resulting in greater accuracy of video color and white-balance control." A high sampling speed of 240 megahertz supports PC display formats up to UXGA (1600 x 1200) resolution, and also has the required speed for all 18 ATSC formats for DTV, including the highest HDTV production format of 1920 x 1440 pixels at 60Hz.

"TI's new THS8135/36 DACs address the convergence of consumer video and PC graphics, offering versatility, improved quality, and low power consumption for a new generation of multifunctional video applications," said Bart DeCanne, digital video marketing manager for TI. "The new solutions are the next step in TI's continuing strategy of supplying flexible solutions that enable our customers to convert a wide range of video formats from digital into a real-world analog signal."