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National's CML devices with 25ps jitter

Posted: 17 May 2006     Print Version  Bookmark and Share

Keywords:DS25BR400  DS42BR400  DS25MB200  DS42MB200  buffer 

National Semiconductor Corp. has introduced four current-mode logic (CML) signal-conditioning buffers and multiplexers with 25ps of jitter. The products feature integrated equalizers and programmable pre-emphasis for low-jitter and error-free transmission of multigigabit traffic over PCB materials, copper cabling and fibre optics. The products' serial I/O performance, 6kV of ESD protection and added redundancy are said to enhance ASICs and FPGAs data-transmission performance.

The DS25BR400 and DS42BR400, configured as quad transceivers or eight-channel buffers, provide integration for high-speed data-transmission applications. The DS25BR400 operates up to 2.5Gbps and the DS42BR400 operates up to 4.25Gbps. The DS25MB200 and DS42MB200 are dual, signal-conditioning 2:1 multiplexers and 1:2 fan-out buffers (dual channel mux-buffers) designed for use in redundancy data paths.

National claims its buffer and multiplexer family enables error-free transmission across more than 80 inches of FR-4 backplanes. Backplane applications include XAUI and fibre channel, as well as the standards for 3G cellular base stations such as the common public radio interface (CPRI) and open base station standard architecture initiative (OBSAI). The products also work at up to 15m of PCI Express, SATA, CAT6/CAT7, DVI, HDMI and Infiniband cables.

An input equalizer that removes inter-symbol interference (ISI) jitter precedes each input buffer, compensating for up to 5dB of transmission loss, which is said to result in reducing output jitter to as low as 25ps. The outputs feature adjustable de-emphasis to reduce deterministic jitter. The products also offer edge rates of up to 80ps, channel-to-channel noise immunity, low output skew and power at less than 140mW per channel.

Signal-integrity features include: a fixed equalizer at each input stage to reduce ISI distortion; four selectable steps of de-emphasis on each output driver to compensate for transmission loss; CML drivers and receivers internally terminated with 50-ohm pull-up resistors; LVDS-compatible inputs and loop-back control in each direction to enable at-speed system testing.

Available in a 60-pin LLP package, the DS42BR400 operates as a quad transceiver or an eight-channel buffer up to 4.25Gbps or down to 250Mbps. The operating range enables use of the buffer in applications requiring both low- and high-frequency data rates. The DS25BR400 has the same features and packaging as the DS42BR400, but features 250Mbps to 2.5Gbps data rate for 4x PCI-Express, CPRI and OBSAI applications.

Available in a 48-pin LLP package, the DS42MB200 is a dual, signal-conditioning 2:1 multiplexer and 1:2 fan-out buffer designed for use in backplane redundancy applications. The DS42MB200 operates from 0.8Gbps to 4.25Gbps. The DS25MB200 has the same features and packaging as the DS42MB200, but offers 0.8Gbps to 2.5Gbps for 2x PCI-Express, CPRI and OBSAI backplanes.

The buffer/multiplexers are currently available. In 1,000-unit quantities, the DS42BR400 is priced at Rs.879.65 ($19.50), the DS25BR400 is Rs.642.82 ($14.25), the DS42MB200 is Rs.868.37 ($19.25) and the DS25MB200 is Rs.473.66 ($10.50).

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