National Semiconductor has designed the industry’s first configurable I/O chip for serial digital interface (SDI) broadcast video equipment. It should simplify designers’ tasks by providing the flexibility to program their bayonet fitting interface connectors (BNC) as either inputs (equalizer) or outputs (cable driver).
The new device, designated the PowerWise LMH0387, targets 3G/HD/SD video capture and editing cards that have a limited number of coax BNC connectors. It also suits the processing and distribution equipment that is compatible with a variety of I/O configurations.
This is important because in the past, SDI ports were fixed as inputs or outputs, and designers had to build one card per I/O configuration. Equipment manufacturers, then, had to budget for research and development and for the inventory holding costs of supporting multiple design configurations.
The LMH0387 cuts the number of individual I/O configurations and associated costs. Also, the universal BNC interface allows manufacturers to program their equipment I/O configurations post-delivery during studio installation. For example, a compact router frame with 64 BNCs may be configured as a 32-by-32 matrix, a 1-to-63 distribution amplifier, or any other combination of inputs and outputs to meet the application’s particular demand.
Further, the LMH0387 is the first solution to integrate the complex return loss network. This not only eliminates the time-consuming and costly process of tweaking passive component values to achieve spec compliance, it also ensures compliance with the Society of Motion Picture and Television Engineers (SMPTE) 424M return loss specification time code.
Time codes, which are added to video and audio material, have been adapted to synchronize music. They provide a time reference for editing, synchronization, and identification. With the SMPTE 424M and the related SMPTE425M, two streams of data can be managed in one cable.
The LMH0387 uses the same I/O pin for both input and output functions. It operates over a wide range of data rates from 125 Mbits/s to 2.97 Gbits/s, which means it not only supports SMPTE 424M but also SMPTE 292M, SMPTE 344M, and SMPTE 259M specifications. It equalizes up to 120 m of Belden 1694A coaxial cable at 3G rates, 200 m at high-definition rates, and 400 m at standard-definition rates.
In the input mode, the device offers a power-saving sleep option, programmable output common-mode voltage and swing, cable length indication, launch amplitude optimization, input signal detection, and an SPI-compatible serial interface.