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3-Gbps SDI equalizer yields low jitter across cable lengths

Las Vegas—A PowerWise 3-Gbps (3G) serial digital interface (SDI) cable equalizer (EQ) from National Semiconductor Corp. is aimed at simplifying the design of broadcast video routers, production switchers, distribution amplifiers, editing and conversion equipment.

According to National, the LMH0384 offers the industry's lowest output alignment jitter across cable lengths, allowing hardware designers more headroom for designing within system jitter budgets.

The LMH0384 EQ guarantees less than 0.3 unit intervals (UI) of output jitter from zero to 110m of Belden 1694A coaxial cable at 2.97-Gbps. It equalizes up to 140m of cable at 3G rates, 200m at high-definition (HD) rates and 400m at standard-definition (SD) rates. The device adaptively adjusts equalization levels based on cable length to receive incoming signals and provide low-jitter transmission of 1080p high-definition (HD) broadcast video at up to 60 frames per second over a single coaxial cable. National will demonstrate the LMH0384 at the NAB show in Las Vegas from April 20-24 at Booth SU2804.

National's LMH0384 supports two modes of operation: pin mode and register mode. In pin mode, the EQ is fully backward-compatible with National's other SDI equalizers. Register mode opens up a suite of advanced features—accessible via serial peripheral interface (SPI) bus—that enable flexibility to change and diagnose product parameters without requiring a board re-spin. These include automatic power down (auto-sleep), cable length indicator, LVDS drivers with programmable offset and amplitude, and programmable input launch amplitude to facilitate operation with external splitters. The LMH0384's 1.05V to 1.85V adjustable output common-mode voltage eliminates the need for level-translation buffers by facilitating direct coupling to most FPGAs and signal conditioning devices.

The EQ offers active sensing features to minimize power consumption and reduce cooling requirements in customer systems. For example, in the event of cable detachment or loss of signal, the LMH0384 enters a power-saving auto sleep mode to reduce power consumption by 85 percent. In active mode, the EQ automatically shifts equalization stages at shorter cable lengths (less than 140m) to reduce power consumption by 20 percent. The EQ typically consumes 230 mW of power from a single 3.3V supply.

Pricing: Offered in a 16-LLP package, the LMH0384 is priced at $21 each in 100-unit quantities.
Availability: Sampling now, with production quantities scheduled for May 2009.
Datasheet: click here.

National Semiconductor, www.national.com

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