Boundary scan modules access complex boards

JTAG Technologies has a new family of digital I/O scan modules for enhanced testing of complex printed circuit boards.

JTAG Technologies has a new family of digital I/O scan modules (DIOS) for enhanced testing of complex printed circuit boards.

The JT 2128 DIMM DIOS series covers the complete range of standard and small outline DIMM connectors with pinouts from 100 up to 300 pins and supports "self-adaptive" voltage levels for a wide range of operating voltages.

What's more, the new DIOS modules contain programmable logic and a built-in 10MHz oscillator, allowing implementation of custom functionality for embedded test instruments such as counters, function generators, timers etc.

The DIOS modules enhance test coverage via parallel drive and sense test points with self-adaptive voltages to match today's low-voltage IC technologies.

Drive and sense channels are offered via a JEDEC-compatible connector interfaced with JTAG Technologies' boundary-scan test systems.

The mechanical form and pin arrangement of the DIMM DIOS modules follow the JEDEC Standard 21C allowing easy integration within a production test fixture using standard connectors or directly on a target PCB and providing access in close proximity to the test points.

The new JT 2128/168 DIMM DIOS specifically supports JTAG Technologies' existing standard fixtures such as JT2702/PCI-slot and JT 2702/DDC dual DIMM carrier.

The other modules in the range support the following socket types: 100, 168, 184, 200, 240, 278, 300, 144so (small outline), 200so and 214so.

Each DIMM DIOS has between 100 and 278 boundary-scannable I/O channels depending on the model.

Channels can be grouped to three or four to reduce chain length by bypassing groups and increase test throughput.

The JTAG TAP signals are by default routed via the DIMM edge connections, but can also be connected via an external connector.

Up to ten DIOS DIMM modules can be daisychained together in a mix of module types.

The I/O channels are individually programmable as input, output, bidirectional, or tristate signals.

The DIMM DIOS modules are available for 2.5-5 and 1.8-3.3V voltage ranges.

Within these ranges the input thresholds and output voltage levels are self-adaptive to the levels as required by the target.

By configuring logic on the DIOS module and using the onboard 10MHz oscillator, the test designer can implement a wide variety of additional functional capabilities, enabling boundary-scan to fully support a broader test strategy.

For example, a target circuit board may contain elements that cannot be accessed directly by boundary-scan such as board-edge connectors or non-boundary-scan logic clusters.

In such cases, the overall testability of the board is compromised, allowing some manufacturing faults to be undetected.

The DIOS modules overcome this problem, extending the reach of boundary-scan to include testing of circuit board edge connectors and providing extra test points internal to the PCB to improve fault coverage.

The hot-swap feature offers improved test throughput by allowing test targets to be connected/disconnected from the fixture without cycling power.

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