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Testing

A Tall Tale: What’s Luck Got to Do With It?

Rising above the tidal marshes of Southern New Jersey stands a red and white antenna tower shadowing a World War II era radio shack. The marsh was a simple mosquito nursery in the 40s when the first modest building—a cinder block foundation and stick-framed walls— was erected as part of a string of radio stations that formed a wartime network on the East Coast. German subs prowled the waters just off the shore of Cape May which hosted just a few houses and one general store with peeling gray paint and sway-back roofline.

Navigating the New World of ENERGY STAR

ENERGY STAR has created a completely new system of requirements and procedures for qualifying energy-efficient products. Navigating the new routes to qualification can be a challenge, given the multiplicity of newly defined requirements for testing, certification and verification. What are Recognized Laboratories, Certification Bodies and Accreditation Bodies? What roles do they play in the process? Can manufacturers still perform their own product testing for qualification? This article will chart the landscape and describe how to choose the fastest and most economical route through EPA’s Enhanced Testing and Verification Program.

Narrowband and Broadband Discrimination with a Spectrum Analyzer or EMI Receiver

Spectrum analyzers and scanning receivers are widely used in EMI laboratories today. Their use for measuring both narrowband and broadband signals requires specific understanding of certain instrument and signal characteristics in order to correctly interpret the displayed results. This article explains methods for the discrimination between narrowband and broadband signals and provides guidance for the proper operation of test instrumentation.

Use of Third Party EMC or Radio Test Laboratories

There are numerous reasons for the use of an external test laboratory by organizations developing, manufacturing or marketing electric or electronic products. These reasons may include lack of or limited testing capability, scheduling conflicts within the organization, etc. Whatever the case may be, the proper selection of an external third party test laboratory is critical since the test results may be used to demonstrate product compliance or to verify changes to a product design.

Decreased CDM Ratings for ESD-Sensitive Devices in Printed Circuit Boards

Many sources recently have reported that electrical failures to components previously classified as EOS (Electrical Overstress) are instead the result of ESD (Electrostatic Discharge) failures due to charged-board events (CBE) [1,2]. A charged printed circuit board assembly stores substantially more charge than a discrete device as its capacitance is larger. A subsequent discharge of the board assembly results in increased current for that event - versus that of the discrete component. Consequently, a device’s CDM (charged device model) rating is lowered when mounted in a printed circuit board (PCB). In an attempt to get a feel for just how much it is lowered, we conducted CDM stress tests on components in discrete form, and again after insertion into larger and larger sized pc boards. We found that the CDM ratings are lowered dramatically!

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Discovering EMC’s Role in Functional Safety

Electromagnetic disturbances can greatly influence the performance of equipment and the functional safety of systems. Consider the current problems we hear in the news with unintended acceleration in some vehicles. While this complication’s true cause may never be determined, analysts have theorized that electromagnetic disturbances could play a large role. Due to the amount of electronics and ever changing technologies found in today’s automobiles, unintended acceleration is only one of many examples of unwanted anomalies that could occur due to an EMC issue. Automakers are faced everyday with the risk and associated liability that could come with a problem such as this once the vehicle is on the street with the consumer. That risk is why the automakers over time have had to develop specific test standards that relate to the EMC concerns of their vehicles and enforce their suppliers to meet them by way of specific test plans. The automotive industry is just one example of how EMC can relate to the functional safety of a product as guided by IEC TS 61000-1-2: 2008.

Simulating Small Device CDM Using Spice

In earlier articles in this publication we have discussed the charged device model (CDM) testing of small devices. In the first article we demonstrated that the peak current for small devices does not become vanishingly small.1 The commonly held belief of vanishing current for small devices was shown to be an artifact of measuring the current with the 1 GHz oscilloscope2 specified in the JEDEC CDM standard.6 The second article explained various ways to make CDM testing of small devices more reliable with the use of small surrogate packages, or the use of templates to hold the device during testing.3 In this article we will show how insight can be gained into the CDM testing of small devices using a simple three capacitor circuit model.4, 5

Testing for Immunity to EMP

The 21st century as we know it, truly reflects the age of technology. Every aspect of life today is encompassed by the use of some sort of microprocessor based electronics intended to simplify tasks, to improve processes, and improve efficiency. Electronics are used to communicate with loved ones, manage finances, fly aircraft, even save lives. As greater advances in technology are achieved, electronics are found controlling more important safety critical functions at an exponential rate. Although electronics have provided us with obvious benefits, the increasing reliability on electronics has elevated our vulnerability to the effects electromagnetic pulses.

Necessity But Insufficiency of Interoperability Measures to Assure Smooth Operation of the Wireless Networks

Wireless alliances like Wi-Fi and ZigBee certify wireless devices for interoperability which to the end user provide a confidence level of smooth operation between these devices from different manufacturers. For instance this level of interoperability is necessary (but not sufficient) to ensure communications on WLAN Wi-Fi segments containing an Access Point (AP) and a number of wireless client cards. The same concept applies to ZigBee networks where interoperability gives a confidence level for ensuring operation of devices such as a light bulb and a switch, an RF4CE remote control and paired TV, DVD player or set top box, but also insufficient to assure seamless operation of the network over time and under variable environmental conditions especially in demand-response time critical scenarios.

CDM Testing of Small Integrated Circuits

Integrated circuits are classified for ESD robustness using a variety of tests. The most popular tests are Human Body Model (HBM) and Charged Device Model (CDM). These two ESD classifications are intended to indicate how well a circuit will survive ESD stresses in manufacturing environments which include basic ESD controls. HBM is the oldest of the ESD tests, but factory ESD control experts generally agree that CDM is the more important test in modern, highly automated, assembly operations. The amount of stress for CDM scales with the size of the device. For that reason “conventional wisdom” on CDM has often stated that you don’t need to test very small integrated circuits because the peak currents get vanishingly small. In last month’s article for IN Compliance [1] we presented an article showing that the peak current for very small devices does not become vanishingly small as often thought. Measurements with a high speed oscilloscope demonstrated that peak currents remain surprisingly high even for very small devices although the width of the pulse gets very narrow. In the past these high peak currents were missed due to the use of 1 GHz oscilloscopes as called for in the standard for the field induced CDM test [2], the most popular form of CDM testing.

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