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avoidance of IC sockets, and simplify- ing the process flow.


Improved Stress Testing Boundary-scan tools can signifi-


cantly improve the effectiveness of environmental stress testing, such as HASS or HALT stress testing. Because the boundary-scan interface to the target is implemented over a thin cable which is highly impervious to interference, the test setup is straightforward. Furthermore, boundary-scan


test ing can be set to run continuous- ly so that environmentally induced failures will be detected and fault data collected and time-stamped for later diagnosis. Intermittent faults which might occur only at elevated temperatures,


for example, are


recorded, avoiding “no-trouble- found” situations and preventing the escape of products to the functional test step or, worse, to the field and the customer. Integrating boundary-scan and


Rapid resolution of vital aspects like time-to-


market, repair turnaround times, product quality and reliability translate into improved bottom lines.


functional-testing methods within one platform can provide major bene- fits to a manufacturing enterprise. Savings result from reduced product handling; fewer test stations, less floor space, a reduction in training requirements, and use of a familiar, unified graphical user interface


www.us- tech.com Boundary-Scan Testing


(GUI) to the operator. Boundary-scan technology can


also be considered for system-level application for both test and in-sys- tem programming. This can be per- formed with either an external tester or embedded boundary-scan archi- tecture. In both cases, control of the system-level applications can be con- ducted remotely.


problems in analyzing test results. Furthermore, because boundary- scan requires almost no custom test setups, the repair department can rapidly switch between target types and versions in high-mix situations. In short, if a product has been well planned, including DFT, a manufac- turer can greatly benefit from the use of boundary-scan methods. Transi - tions of responsibility from one organization to the next are stream- lined, interdepartmental communi-


March, 2015


are manifested at operating range limits, user-generated errors, etc. These are the types of faults antici- pated in actual use of a product. Boundary-scan and functional


testing can be combined with great effectiveness using a number of test system control interfaces, such as PCI, USB, Ethernet, LXI, or PXI(e) architectures. Recently, an alterna- tive approach, known as JTAG Functional Test (JFT), provides JTAG/boundary-scan access to digi- tal and mixed-signal circuit elements by means of a Python code program. The use of JFT enables a “boundary- scan only” solution to testing devices such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), or complex logic clusters that rely on conditional branching decisions. Scripts can also be further enhanced by adding (processor) core emulation test capabilities with CoreCommander functions. In this scenario, boundary-scan


Adding the JTAG ICs become a simple part of the assembly operation.


Commercial ICs and software


are available that enable such boundary-scan control to be designed into a target system, which can then execute applications without need for external control. This integrated architecture approach can be employed to advantage in maintain- ing test and programming access to in-service systems. Boundary-scan test methods


can be effective in repair operations. Centralized as well as distributed repair facilities can use the same boundary-scan-based tests as the fac- tory, helping to avoid correlation


cation is enhanced, and correlation problems are avoided by the use of a common test methodology.


Functional Testing Integrating boundary-scan me -


th ods with functional test methods can enhance a product life cycle. Both test methods fulfill the necessary quality assurance steps for the antici- pated fault spectrum. Boun dary-scan testing is well suited for identifying manufacturing faults,


typically


caused by soldering problems, while functional testing is suitable for at- speed problems, such as faults that


vectors for testing, JFT scripts and ISP of PLDs and flash memory device, developed for use in the prior prototyping phase, are ported to the production environment and are driven to the circuit board by means of the chosen boundary-scan instru- ment in the functional test chassis. Boundary-scan operations can


be integrated into many functional test environments, such as custom GUIs or industry-standard test soft- ware tools (TestStand, LabVIEW, and others). The controller drives the vectors to the target and collects the results. If failures have been detect- ed, they are analyzed with the same diagnostic routines available to the designer. JTAG/boundary-scan ISP applications can then be executed to “breathe life” into the target prior to the next test phase.


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