Universal SRAM Test System Based on NI PXI Solutions

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"We gave our customer, Promtehnosert, a universal test solution intended for a wide range of SRAM memories. We took advantage of the flexibility and modularity of the NI PXI platform to build an easily expandable solution that users can configure to support a wide range of memory ICs. We used LabVIEW to develop this advanced test system, which can conduct the most popular memory tests and create custom tests."

- Arev Hambardzumyan, RAFA Solutions LLC

The Challenge:
We needed a turnkey solution for the functional test of static random access memories (SRAMs) that could support a wide range of memory models (more than 2,000). The solutions needed to be expandable, easy to use, and able to conduct a full memory test within a short amount of time.

The Solution:
We developed a solution that uses the modularity of NI PXI solutions to expand system capabilities and the flexibility of LabVIEW to build a universal software application. The system includes custom-developed hardware that works as an adapter between the PXI and device under test (DUT).

Author(s):
Arev Hambardzumyan - RAFA Solutions LLC
Rafayel Ghasabyan - RAFA Solutions LLC

About RAFA Solutions

RAFA Solutions is a systems integrator company that specializes in smart machines and data acquisition/control systems. We deliver robust and flexible advanced solutions for machinery control and automation. Established in 2012, our company is an NI Silver Alliance Partner and proficient in using NI technologies. We provide electronics design and software development services for material testing and semiconductor testing industries. Our clients are machine builders who are innovative in their technologies and build the smartest machines in their fields of application.

RAFA Solutions holds CSIA Certified status in the CSIA Best Practices and Benchmarks certification program. This is the highest level of certification available in the control systems integration industry, and we are one of the first companies to receive this recognition in the region. The company is also awarded with ISO 9001:2015 quality certification, which is the latest revision of the world’s most recognized quality management systems standard.

Problem Background

We test integrated circuits (ICs) in different stages of manufacturing and utilization. Manufacturers conduct various tests to validate the design and verify the quality of the product. Consumers, who use ICs in their products, conduct incoming control tests to ensure the use of fault-free parts in their systems. The test of memory ICs sets some specific requirements, such as duration of test, in addition to the most common requirements such as cost and reliability.

We designed a high-performance, low-cost memory test solution, which delivers high efficiency for asynchronous SRAM memory testing. The system can perform functional tests of SRAM memories, as well as measure a set of electrical parameters.

The system comprises the NI hardware platform, custom developed adapter boards, and the software. We based the system on the NI PXI platform. We used PXIe-6556 200 MHz digital waveform generator/analyzer modules, which feature a per pin parametric measurement unit. The tester has four configurations that support two, four, six, and eight PXIe-6556 modules. The largest configuration of the system provides up to 192 digital channels.

Figure 1. NI PXI System With Four PXIe-6556 Modules Connected to the Test System

The custom-developed hardware comprises the adapter boards, socket connector boards, and a set of sockets that support a wide range of IC packages. We can stack the adapter boards to create a system that supports up to eight high-speed digital I/O PXI modules. The adapter board implements functions of digital line multiplexing, which makes it possible to connect a power line or digital line to any pin of the IC. The socket adapter board supports a wide temperature range, from -55O ˚C to +80O ˚C, so we can test the memory ICs in a temperature chamber.

Figure 2. 48-Pin Connector Board (left) and Adapter Board (right)

The described functionality means we can test even custom memory ICs, in which the pinout of the memory package is not designed according to any standard. We can connect any pin of the integrated IC to the power supply, ground, or digital channel of the PXIe-6556 module. The PXI-4130 module supplies the power of the memory IC and can set any value within a wide range of supported voltage values. We can use parametric tests to measure the current consumption of the IC and output voltage levels of digital channels.

We easily achieved parametric test functionality using per-pin measurement capabilities of the high-speed digital modules. We used the digital waveform generator modules to have 1 ns resolution when creating and generating custom timing profiles for the control of the memory ICs during the test.

Figure 3. 90-Pin Connector Board With Socket and DUT

We did not develop the test system’s sophisticated software for specific models of memories, but rather to create and run tests for any memory, if a system’s hardware meets the IC requirements. We can use the software to create SRAM IC profiles, timing profiles, and custom tests using a graphical interface. A wizard-based interface does not require any programming knowledge and makes it easy to set up, create, and run tests. The solution does not require any additional software or a programming environment.

Figure 4. IC Profile Creation Screen of the Software Application

The software has separate sections where users can create IC profiles, assign functionality of each IC pin, or create custom timing profiles to validate the functionality in boundary conditions. The test creation part empowers users to configure the sequence of various stages, which include parametric test stages or functional test stages. The system includes well-known algorithms for the memory test—Checkerboard, MATS, MARCH C-, and more. Users can create their own tests, making custom data arrays that can be written and read from the memory. Users can also conduct functional tests for the whole memory, or only in the predefined sections, providing required addresses. We also automated creation of the test data arrays, so users can create checkerboard arrays, random data arrays, or set any row or column to constant value, which simulates address or data line fault conditions. The system presents test results with tables or graphs. We used the LabVIEW graphical programming environment to achieve all the flexibility of the software solution and to drastically reduce development time.

Figure 5. Timing Profile Creation Screen of the Software Application

Solution Benefits

Our turnkey solution is a low-cost test system that supports SRAM ICs in almost all available packages. It runs functional and parametric tests, and delivers comprehensive results within less than five minutes of the test duration. Users can easily expand the system by adding digital I/O modules and adapter boards and increasing the number of digital channels to support high-pin-count ICs. The software allows full configuration of test steps, algorithms, and test conditions.

Conclusion

We used the NI PXI platform and LabVIEW to build a test solution that fully meets the set requirements. We gave our customer, Promtehnosert, a universal test solution intended for a wide range of SRAM memories. We took advantage of the flexibility and modularity of the NI PXI platform to build an easily expandable solution that users can configure to support a wide range of memory ICs. We used LabVIEW to develop this advanced test system, which can conduct the most popular memory tests and create custom tests.

Author Information:
Arev Hambardzumyan
RAFA Solutions LLC
45a Mashtots Ave, #92
Yerevan 0009
Armenia
Tel: +1 (512) 782-9747
arevh@rafasolutions.com

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