Wireless charging has shifted from being a purely accessory oriented market to being embedded directly in high end devices, such as mobile phones, phablets, tablets. The motto of standard promotion groups such as the Wireless Power Consortium is very clear: now is the time to cut the power cable, and act in favour of global mobility.
Let’s take a look at what’s happening at STMicroelectronics for Wireless Charging TX products, with Christain Beia, Product Marketing Manager. Micropross asked him a few questions about his wireless charging team testing requirements and how Micropross test equipement could accelerate their time to market, while still making no compromise on the quality of their products.
Micropross: What was your main challenge regarding your wireless charging product ?
Christian Beia : 'It was obtainning the certification quickly, with an uncompromised quality. For the market launch of STWBC-EP, our new 15W TX, the WPC certification of our STEVAL-ISB044V1 reference design was a must. This allows to prove to our customers that embedding our IC, they can easily obtain certification from the WPC on their own design and put the Qi logo on it. This certification process leverages a network of authorised test laboratories, scattered in various places in the world, mostly in Asia.
MP: What are you expecting from your test tool ?
CB: We were looking to offer our customers the best in class products, and this is achieved by submitting our designs to extensive test campaigns, which go well beyond the requirements of the WPC certification programme. We therefore need our test tools to offer a high level of flexibility, customise physical parameters, generate packets with errors, in order to precisely characterise the performance of our design, its robustness, and their ability to act in case something unexpected occurs during the power transfer (unfortunately uncertified wireless chargers can be found on the market, which offers no guarantee on their respect of the Qi specification).
MP: Was automation part of your requirements ?
CB: Yes, in order to accelerate our time to market and make the best possible use of our engineering hours. The concept of 'tool automation' applies to different aspects of the user experience. First, during pre-conformance testing, it is very interesting to use an automated test tool because, obviously, this allows to get test results faster.
Then, the validation engineer can be sure that the test procedure is totally repeatable. And finally, using an automated test tool avoids any internal disputes around test specification interpretation. The tool would give a verdict, based on proven result analysis routines, which represent what the verdict would be when going for official device certification testing.
MP: Is automation valuable also during the Validation & Verification (V&V) phase?
CB: Sure! Working with an automated test tool offers numerous benefits. The possibility to play test sequences on the design in an automated manner allows the test operator to get test data faster, to get a deep understanding of the performance of the device under test, and be able to identify issues and correct them before we identify them.
Micropross’ answser to those requirements was a fully automated test bench, combining automation and flexibility.
Stephane Czeck, Micropross Marketing Director will help us undestand Micropross Qi solution offer.
Micropross : What Micropross did to satisfy Mr Beia’s team requirement?
Stephane Czeck: We proposed a fully automated Qi test solution. Sold as a turnkey solution (hardware, software, accessories), the Micropross tool allows to perform all test cases defined inside the Qi specification in an automated manner.
Physical condition generation, timing measurement, and test verdict generation happen without human intervention. All necessary measurement instrumentation is integrated inside the hardware, which makes it useless to use, for example, an oscilloscope to measure timings.
At the end of a test session, it is possible to automatically generate test reports, which can be shared with colleagues, partners, suppliers to exchange information in the most convenient way possible.
Traditionally, a full conformance campaign on the Qi power transmitter would last two days. The Micropross solution makes it possible in just a few hours.
MP: What kind of software Micropross provided with its hadrware?
SC: We deliver a very intuitive graphical user interface called MPManager. It is used not only for the pre-conformance testing as described previously, but also for custom test scripts edition. All physical and protocol parameters can be tweaked, in order to submit the device under test to difficult conditions, see its reaction, and take the appropriate counter measures if needed.
MP: What are the advantages of this User Interface?
SC: MPManager offers a graphical viewer, which offers more than what any oscilloscope could ever provide: the display, during a complete test procedure, of all packets (including their full analysis), timings, voltage and current on the measurement points described by the Qi test specification. And this, even if the test procedure duration exceeds several minutes. It considerably reduce the V&V cycle duration, by using flexible tools, proposing means for the customer to obtain and analyse their test results with an unmatched convenience.
Micropross: What made the Micropross test tool convenient to use ?
Christian Beia: We could add wireless charging feature to our internal test sequencer by using the API that enabled us to take control of the test tool from any programming language that accepts Dll. We have developed dozens of proprietary test cases, allowing to stress our component in all configurations possible.
MP: Did the Micropross test tool allow you to solve challenges that traditionnal instrumentation can not address ?
CB: We managed to leverage the flexibility of the Micropross Qi test tool to measure the overall power efficiency of our component, in transforming into wireless power. To achieve this, we used the API of the Micropross tool, and synchronized it with other general purpose measurement instruments.
MP: What make the difference to work with Micropross?
CB: The relationship between my team and Micropross became a real partnership. If we needed some extra features to get our job done, Micropross included those in the tool development schedule.