National IC eyes boundary scan testing

Electronic News, Oct 18, 1993 by Jeff Dorsch

SANTA CLARA, CALIF. -- National Semiconductor is introducing SCAN Bridge, a controller IC meant to help test entire systems using the boundary scan test standard. The device, a.k.a. the SCANPSC11OF, is available in sample quantities now and scheduled to go into volume production this month. Pricing is $12 each in 100-piece lots.

"The advantages of boundary scan are pretty much well-known," said Gary O'Donnell, National's strategic marketing manager for system test products, citing reduced test programming time; lower-cost test programs, testers and fixturing; higher-quality test programs and manufacturing quality and faster time-to-market. "It's taken about two to three years for boundary scan to go from a standard to a market."

The JTAG boundary scan standard, IEEE 1149.1, was "crafted to test a single board," Mr. O'Donnell said, but now "there's a shift from board-level to system-level test in boundary scan."

SCAN Bridge helps provide a "multi-drop" scheme to testing a series of boards with boundary scan devices in a system design, rather than resorting to cumbersome "daisy chain" or multiplexer testing architectures.

Motorola is using the IC in testing boards for its Iridium satellite program. "The SCAN Bridge device provides an elegant backplane scan bus design solution for partitioning and controlling more than 50 1149.1 boundary scan chains on the Iridium satellite," said Motorola engineer Cary Champlin.

National is working with Teradyne to link SCAN Bridge with the automatic test equipment vendor's Victory boundary scan test generation software. "Gaps between silicon vendors and test equipment companies have historically existed, and both test and design engineers' efforts have suffered as a result," said Mr. O'Donnell. "Such cooperation will bring about integrated hardware and software solutions, easing design and streamlining test on a system level."

Victory will identify SCAN Bridge ICs in a system and automatically generate the appropriate test pattern, according to National. SCAN Bridge is also supported by Fluke's Explorer boundary scan software. To widen boundary scan implementation, Teradyne licensed Victory to a number of companies. Mentor Graphics just introduced a pair of design-for-test packages for printed circuit boards and multichip modules incorporating the Teradyne technology (EN, Oct. 4) and Teradyne recently licensed Alpine Image Systems to sell Victory with its proTEST boundary scan test systems (EN, Sept. 6).

National's chief competitor in JTAG logic, Texas Instruments, last year established a second-source relationship for such devices with Integrated Device Technology (EN, Dec. 14, 1992). National has a similar sourcing relationship with Quality Semiconductor. It hasn't yet established a second source for the SCAN Bridge part, but is in discussions with Quality and other companies, Mr. O'Donnell said.

In another development, National Semiconductor unveiled a highly-integrated 5-volt quad 10-bit serial D/A converter with data readback capability aimed at digital control of analog voltages in instrumentation, test & measurement and process control applications. The DAC1054 is said to combine several discrete components and functions into a single monolithic device, including four 10-bit DECs, four outamplifiers and a Microwire-compatible serial microprocessor interface.

With the device, design engineers can separate output voltage range between 0.3V and 2.8V for each DAC. Its industrial temperature performance is in the -40 to 85 degree C range. The part is currently available in 24-pin DIP and SO packages. Pricing in 1,000-unit quantities begins at $8.91.