HDTV-Compliant DACs Generate Tri-Level Sync Pulses

The path to HDTV set-top boxes and other video/graphics products has been made considerably smoother with the introduction of two new D/A converters. Said to be the first such devices to comply with HDTV video standards as defined by EIA 770-3 and SMPTE-274 and -296, THS8133 and THS8134 ICs each house three DACs, an internal voltage reference, and a current output capable of driving loads down to 37.5 ohms. In addition, the devices also have configuration control logic that can generate either a traditional bi-level synchronization signal or the tri-level sync signal needed for handling the component video signaling of HDTV. By automatically generating the tri-level signals, the DACs are said to significantly simplify the design and reduce the cost of HDTV systems. The devices can handle various input modes in conformance with several professional standards, such as ITU.BT-656 and -601, with the 10-bit THS8133 suited for use in professional video systems, while the 8-bit THS8134 is optimized for the cost-sensitive consumer mart. The DACs are specified for 5V analog and 3V and 5V digital supplies, dissipate only 515 mW (typ.), and are housed in a 48-pin TQFP PowerPADTM package.