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National Semi adds analog voltage monitor

Posted: 23 May 2005 ?? ?Print Version ?Bookmark and Share

Keywords:boundary scan? analog? voltage monitor? jtag?

National Semiconductor Corp. announced the addition of an analog voltage monitor to its industry-leading portfolio of communication interface boundary scan products. The low-power SCANSTA476 analog voltage monitor is controlled via the IEEE 1149.1 (JTAG) bus, and is capable of accurate measurement or sampling of up to eight analog or mixed-signal input channels for verification of power supply and critical reference voltages on printed circuit boards.

Until now, the pervasive and versatile JTAG bus has been a strictly digital tool, commonly employed at the printed circuit board and system level for structural test, FPGA configuration, flash memory programming and emulation. The SCANSTA476 expands the JTAG capability into the analog realm by simplifying measurement of mixed-signal or analog voltages.

"System test, FPGAs, flash memories and system monitoring have made the JTAG bus pervasive in a broad range of applications," said Jeff Waters, product line director for the Communications Interface division at National. "National's SCANSTA476 extends the utility of this existing infrastructure to the analog world, greatly facilitating the implementation and use of analog voltage monitoring by system designers."

Analog voltage monitors are valuable during all phases of the electronic equipment life cycle, including hardware development, environmental test, production and health monitoring in fielded systems. In advanced electronic systems with online system self-monitoring features, the SCANSTA476 expands the reach of the monitoring capability to mixed signal voltages for live system health checks or embedded fault observation and prediction.

System designers who utilize JTAG techniques to debug prototype boards will now benefit from having access to analog nodes. This benefit also extends to those performing production tests in the factory and to hardware in the field. For high-availability systems that require continuous monitoring, designers can now use the existing JTAG bus for embedded analog measurement.

Technical Features of the SCANSTA476 Analog Voltage Monitor

The SCANSTA476 is a low-power, analog voltage monitor used for sampling or monitoring up to eight analog and mixed-signal input channels over a range of 0V to +5.5V. It provides 2mV of typical measurement accuracy at the full scale range of +5.5V.

By adding this component to the board, multiple point voltages can be accessed even when extensive EMI (electromagnetic interference) shielding is used or there is no physical access to the board. In production test, physical access has become more difficult for traditional probing techniques, such as in-circuit or flying probe testers, yet board complexity and semiconductor packaging density continue to increase.

The SCANSTA476 enables voltage monitoring to be embedded into the electronic system, supplementing existing JTAG test techniques and permitting more advanced monitoring functions. It also extends the lifecycle of the electronic system by reducing field service and maintenance costs, while improving system availability with innovative health monitoring features.

Available now in a very small LLP-16 package, the SCANSTA476 analog voltage monitor is priced at $3.50 each in 1,000-unit quantities.

For more information on National's SCANSTA476 analog voltage monitor, visit For more information on National's communication interface products, visit

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