Holger Schierenbeck, Arrow Electronics
Choosing the power supply for a project can be a challenging process. Prototypes cannot be developed without a supply of power, but the exact power requirements may change as the project progresses. It can be wise not to commit to power supply decisions too early.
On the other hand, an off-the-shelf PSU that meets all the requirements such as output voltages and power ratings, as they are understood at the beginning of the project, may not be easy to find. A need for one or more non-standard voltages can also complicate power supply selection. Other features such as logic enable control, manual on/off control, demand for special modes such as constant-current operation or paralleling of outputs, status indicators, protection features, and any applicable regulatory approvals also need to be taken into account.
A time-consuming task
The prospect of searching for a suitable standard power supply can be time-consuming and labor-intensive. An obvious alternative could be to go for a custom power supply, but this, too, can present problems. Bringing up a power supply from scratch is complex and challenging, particularly if aiming for a tight market window. Moreover, custom projects always contain a risk of complications that could delay delivery of the end product. Also, depending on the target market, the intended production volumes may not be enough to justify the associated engineering costs.
One of the key attractions of an off-the-shelf power supply is that it has already been designed, tested and certified, and can be procured when needed, in the right numbers, at a known price. However, when a standard unit cannot meet all the engineering requirements, and a custom design is simply not an option, another solution has to be found.
When to consider configurable
It is sometimes said, in business, that the worst decision is no decision. When it comes to power design, the best decision could be one that can be speedily adapted to meet special requirements or re-optimized as the project develops. Configurable power supplies, backed up by technical support and OEM-grade assembly and test facilities, can provide a solution that offers the desired flexibility.
Arrow offers several families of configurable power supplies from leading specialist Artesyn, which are designed to be cost-effectively tailored to meet individual customer needs. The PSU chassis contains an AC/DC front end with power-factor correction (PFC), and provides slots for the customer’s choice of DC/DC output modules (see Figure 1). These modules are selected from the wide range of options offered for each chassis type. The available chassis types are defined according to height and depth, and are capable of housing various numbers of output modules as indicated in Table 1.
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Figure 1. The chassis houses the AC/DC front-end and the customer’s choice of DC/DC output modules.
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Table 1. Overview of configurable PSU chassis and options.
The iMP family incorporates a PMBus (Power-Management Bus) connection, which allows parameters such as start-up time, ramp slope, sequencing and others to be set via a graphical user interface (GUI). Overall, Cost per Watt is highly competitive, especially given the individualisation offered as well, and the units are compact and offer a variety of options such as choice of airflow and logic-controlled enable/disable.
By offering a choice of AC/DC PFC front-end modules covering the applicable power ranges, and a large selection of single-slot and multi-slot DC/DC output modules with various standard and non-standard output voltages, the full configurable range from Artesyn presents a choice of over two million PSU configurations. Artesyn is a respected leader in power supply technology, with a broad product portfolio, many power patents in force and applied for, and global reach and size to support customers and technical partners anywhere in the world.
OEM-grade design/build service
System designers can often benefit from guidance when specifying an optimal combination of chassis, front-end, and output modules. Arrow Electronics is Artesyn’s largest distribution partner globally and effectively operates as Artesyn’s sales force in Europe. Arrow has also created European configuration facilities that mirror Artesyn’s manufacturing capabilities in Asia, using the same software and test procedures.
Recently, significant investment has been made in technical capabilities for configurable power, as well as stockholding of chassis, modules and supporting components for configurable power supplies. This positions Arrow ideally to support customers seeking individualized power on a quick-turn basis, offering uncompromising performance, quality and reliability.
In addition, Arrow has invested in extensive equipment and facilities including an environmental chamber capable of running tests at temperatures from -70°C to +100˚C, as well as surge testing and EMI testing capabilities.
Configurable power project possibilities
Two recent projects supported with Artesyn’s configurable power solutions are a computed-tomography (CT) scanner and a mass spectrometer. The challenges of both projects were addressed by specially configuring PSUs using modules from the iMP family.
The power demands of the CT scanner project (see Figure 2) correspond closely with several key strengths of a configurable solution. Production volumes, of course, are low, and the customer development team needed a sample to be delivered on a fast turnaround basis. In addition, they needed flexibility to change the output voltages as the project progressed, up until the point where the final product design was frozen and all the power requirements could subsequently be determined.
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Figure 2. Artesyn’s configurable power supply range delivered a cost-effective solution in low unit volumes, tailored to the needs of a CT scanner application.
The resulting specification imposed complex demands best satisfied by taking the configurable approach as opposed to searching for an off-the-shelf unit. The resulting iMP PSU created by the design team, supported by Artesyn technical staff, provides three outputs of 12V, 24V and 48V, each with an adjustment range of 10%, and is extremely mechanically robust and capable of withstanding high g-forces as the assembly is rotated to perform 360-degree scans.
The power challenges of the mass-spectrometer were also solved by leveraging the flexible configuration options of Artesyn PSU modules. Again, the project engineers needed the flexibility to finalize output voltages at a later stage in development, after important design decisions had been made. In addition, several non-standard voltages were needed: this is a requirement that can be addressed more quickly and easily using configurable units than, for example, full custom PSUs. The final spectrometer design needed a total of eight output voltages between 5V and 60V, including 28V, 36V, and a ±15V dual supply. Other technical requirements were similar to those of the CT-scanner, calling for a wide adjustment range of 10%.
In a further project, to configure a power supply for an industrial laser application, Artesyn’s µMP family was identified as the optimum configurable-power platform (see Figure 3). The requirements for the laser power supply included four isolated outputs at voltages of 24V and 48V, with a broad adjustment range of 50% to 100% of maximum voltage on the higher-voltage outputs. Further special requirements included inhibiting of selected outputs under certain operating conditions, such as at power-on, to ensure the various subsystems are energized in the correct sequence. The low production volume, special technical requirements, and need for flexibility during the project made an Artesyn configurable PSU a perfect solution.
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Figure 3. µMP family was identified as the optimum configurable-power platform
Engaging with the service
Arrow’s facility has built and tested over 15,000 configurable PSUs to date, using these proven procedures and equipment. Designing a suitable power supply begins with capturing the complete set of requirements. Arrow’s power team leverages its close links with Artesyn when reviewing the technical requirements for new projects. This helps to ensure that the modules selected are compatible with the overall system needs.
The power supplies are built using Arrow’s dedicated manufacturing facilities, which are equivalent to Artesyn’s own manufacturing plants in Asia and use identical software. All units are tested at Arrow according to Artesyn’s established test procedures and parameters.