Clock devices target mission critical applications

Fremont, Calif. — Exar Corp. has expanded its clock and timing portfolio with two intelligent dynamic clock switch (IDCS) products that offer high performance, integrated redundancy and minimized clock skew.

Clocks produce a timing reference and repeat impulses for synchronizing the overall system. The IDCS devices (XRK79993 and XRK79892) deliver the increased system reliability needed for mission-critical next-generation applications including wireless basestations, network switches, routers, and storage among others.

With these latest devices, Exar has extended its analog, phase-locked-loop (PLL) capabilities and is now targeting the low power, low output skew and fail-over scheme requirements found in high reliability systems, said Bahram Ghaderi, vice president and general manager, Network and Transmission Products Division.

The XRK79993 and XRK79892 are cost-effective, low-skew 400-MHz clock generators for applications with redundant clock tree requirements that are capable of generating five LVPECL outputs from two LVPECL inputs. Two of the output pairs regenerate the input signal frequency and phase, while the other three pairs generate 2x (for XRK79993) and 4x (for XRK79892), phase aligned clock outputs. Whenever the built-in IDCS detects a failure on one of the two clock inputs, it automatically switches the PLL reference clock to the other input while minimizing the output phase transient. Additionally, the external PLL feedback can be used to provide zero delay buffer performance.

The XRK7993 and XRK79892 dynamic clock switch (DCS) circuit continuously monitors both input clock signals. If the primary clock fails, the DCS will switch to a secondary clock completing phase and frequency alignment with minimum output phase disturbance. This process eliminates the typical phase bump caused by a failed clock signal.

“Our programmable skew clocks solved board-level trace issues, and the IDCS devices have innovative features including a dynamic switch, alarm, manual override and others that enable our customers to easily develop applications that increase over all system reliability.” said Sergis Mushell, senior strategic marketing manager, clock and timing products.

For commercial temperatures the XRK79993 is priced at $8.75 and the XRK79892 is $8.75 in 1,000-piece quantities. Samples of the XRK79993 and XRK79892 are available now in 32-pin, LQFP packages.

Data sheet for the XRK79892.

Data sheet for the XRK79993.

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