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Voltage monitor expands JTAG capability into analog realm

Santa Clara, Calif. — National Semiconductor Corp.'s analog voltage monitor is a low-power device that enables embedded voltage monitoring in servers and computing, telecommunications and industrial applications.

The monitor is controlled via the IEEE 1149.1 Joint Test Action Group (JTAG) bus, and is capable of accurate measurement or sampling of up to eight analog or mixed-signal input channels over a range of 0 V to +5.5 V for verification of power supply and critical reference voltages on printed-circuit boards. It provides 2 mV of typical measurement accuracy at the full scale range of +5.5 V.

Until now, the 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 monitor expands the JTAG capability into the analog realm by simplifying measurement of mixed-signal or analog voltages, said Jeff Waters, product line director for the Communications Interface division at National.

Prototype debug using JTAG will now benefit from having access to analog nodes using simple JTAG techniques, Waters said. This benefit also extends to factory production test and into the field. For high-availability systems that require continuous monitoring, designers can now use the existing JTAG bus for embedded analog measurement, he added.

By adding this component to the board, multiple point voltages can be accessed even when extensive electromagnetic interference (EMI) 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 continues to increase, Waters said.

A key feature of the SCANSTA476 is that it enables voltage monitoring to be embedded into the electronic system, supplementing existing JTAG test techniques and permitting more advanced monitoring functions.


Available now in a LLP-16 package, the SCANSTA476 analog voltage monitor is priced at $3.50 each in 1,000-unit quantities.Click here for the SCANSTA476 data sheet.

National Semiconductor , 1-800-272-9959, www.National.com.

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