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Multichannel clock buffers optimize embedded designs

Posted: 28 Jul 2008 ?? ?Print Version ?Bookmark and Share

Keywords:clock-distribution ICs? precision clock management? multimode?

STMicroelectronics has announced the first six devices in a series of clock-distribution ICs, which are the first in the market to provide per-channel output-enable controls for precision clock management in embedded and handheld applications.

The two-channel STCD1020, three-channel STCD1030 and four-channel STCD1040 save component count, board complexity and BOs costs in multimode devices such as cellular handsets and M2M (machine-to-machine) communications. By distributing a single master clock to multiple clock domains, designers can eliminate multiple individual-crystal clock sources for chipsets supporting GSM, Bluetooth, WLAN, WiMAX or other RF communications, and STBs. With fewer crystal components, these applications also benefit from greater physical ruggedness.

The individual output-enable controls combine with a fast startup time, as well as 2.6mA typical quiescent current and 1?mA standby current for the STCD1040, to minimize power consumption in battery-powered and embedded applications. From receipt of an Enable signal, the selected channel's output is stabilized within 50?s from standby. The power savings deliver advantages such as longer battery life, easier thermal management and smaller physical size. The STCD1040 draws 30 percent less current than a discrete 4-channel solution, which requires five individual emitter-follower circuits and typically occupies over 60 percent more PCB area. High channel isolation also ensures low crosstalk, which can be difficult to achieve with discrete components. In addition, low phase noise directly enhances signal quality.

Designed for transmission of a single-ended sine-wave or square-wave in the range 10MHz to 52MHz, these clock-distribution ICs also integrate an AC coupling capacitor to further minimize external components. They are capable of driving loads up to 20pF to simplify output circuitry. The standard supply voltage is 2.5V to 3.6V, while the option of 1.65V-2.75V operation allows use with low-voltage peripherals. The specified operating temperature range of -40C to 85C allows use in a wide variety of commercial and industrial applications.

The devices' small TDFN packages deliver additional space savings, with the STCD1020 offered in a 2mm x 2mm 8-lead package, the STCD1030 in a 2mm x 2.5mm 10-lead package, and the STCD1040 in a 2mm x 3mm 12-lead package. The STCD1040 is priced at 80 cents in quantities of 10,000 pieces.





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