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National unrolls 'smallest' multirate video relocker

Posted: 12 Sep 2006 ?? ?Print Version ?Bookmark and Share

Keywords:National? LMH0056? multirate video relocker?

National's multirate LMH0056 SDI video relocker

National Semiconductor Corp. has introduced a multirate video reclocker that supports both standard-definition and high-definition (SD/HD) serial digital interface (SDI) data transmission. National said its LMH0056 SDI reclocker is the industry's smallest and lowest power multirate reclocker with a 4:1 input mux.

The new device complements the company's previously released LMH0044, an adaptive cable equalizer, and LMH0002, a cable driver, to form a complete chipset for SMPTE- 292M and SMPTE-259M serial routing and distribution applications such as video routers, switches, distribution amplifiers, processing, editing and conversion equipment. It also fully supports the DVB-ASI digital television distribution standard at 270Mbps.

In a 48-pin LLP package that is said to be 40 percent smaller than competitors' solutions, the LMH0056 automatically recovers the data and clock signals from incoming SDI streams. It removes high-frequency jitter components from the signal to produce ultraclean data and clock outputs. Typical power consumption from a single 3.3V supply is 350mW, about half that of competitive solutions, the company said.

Technical Features
SDI reclockers typically receive the output from a digital crosspoint switch in video router and switcher applications. The reclocker removes the jitter from the signal prior to processing or driving serially over coaxial cable. The LMH0056 integrates a 4:1 input mux for dynamic selection of incoming signals. For systems that require an independent, dedicated reclocker for each SDI channel, designers may use the LMH0046 HD/SD reclocker with no input mux.

According to the company, the LMH0056 supports the most critical data rates for SD SDI and HD SDI serial routing and distribution, including 143Mbps, 270Mbps, 1.4835Gbps and 1.485Gbps. By narrowing the range of supported data rates, National said designers of this device optimized the architecture of the internal VCO to maximize performance at selected data rates. The result is superior jitter tolerance and lower output jitter, for a cleaner, lower noise signal on the output, said the company.

The two differential outputs of the LMH0056 easily interface with differential inputs on National's LMH0202 dual HD/SD cable driver for applications that require multiple SDI outputs with efficient return loss and limited board area.

A minimum of 0.6 unit intervals (UI) of jitter tolerance allows the LMH0056 to successfully recover signals with greater than 60 percent of the eye pattern closed, or collapsed due to accumulated jitter, and still produce ultraclean, low-jitter data and clock outputs, National said. Output jitter of 0.02 UI at SD rates of 270Mbps and 0.05 UI at HD rates of 1.485Gbps is said to be the lowest in the industry. Dual-differential reclocked outputs and an optional low-jitter data-rate clock maximize designer flexibility. A single 27MHz reference frequency provides designers the choice of either a widely available 27MHz system clock or low-cost 27MHz external crystal.

Additional features include lock detect, manual rate select, LVPECL serial inputs and outputs, auto/manual bypass and an output mute function for data and clock.

The LMH0056 costs $33 each in quantities of 100 and samples will be available in Q4 2006.

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Related Datasheets
Part Number Description Category
? LMH0056 HD/SD SDI Reclocker with 4:1 Input Multiplexer EDA - Embedded Systems Design



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