A key requirement when specifying a PSU is the AC input voltage range and another consideration within the CPE industry is “universal or single range AC input?” In this article, we will be exploring the pros and cons of each approach.
Universal Range Input
A universal range input (100-240VAC) is required for use in countries that have dual input ranges, for example, Brazil. When specifying a desktop CPE PSU, a universal input can be the logical decision, especially if the product is being deployed across multiple countries with different AC voltages. A single desktop
PSU can be configured to the country’s voltage simply by changing the AC cable.
One PSU design that can be qualified for worldwide deployment which can in turn reduce the total product development / qualification costs. However, it can drive up the number of safety accreditations and certifications which are required at the power supply level.
Additional component costs are also required to support the wider ranges of both voltages and currents seen on the input of the power supply which can also add cost.
Another challenge with universal range inputs lies in meeting energy efficiency requirements across low (DOE VI, NRCan) and high (CoC V5.2) line AC input ranges. Lastly, inrush current compliance over the universal input voltage range (at a low cost) can have a significant trade-off vs standby-power dissipation.
Single Range AC Input
A single range input (either 100-120 or 200-240VAC) is compatible with the vast majority of countries that utilise a single AC input range without regional variations.
One standout benefit of a single range AC input is the fact that wall-mount PSU formats can be “keyed” to a given country / voltage range via the AC pin configuration.
It is also possible to share a single PCBA between low-line and high-line AC input models to control product development / qualification costs. However, safety certifications can be limited to the applicable countries where the product is being deployed.
The key economic benefit is the fact that single range AC input products will always have a lower unit cost than their universal counterpart. Moreover, single range AC inputs offer an ease of simultaneous compliance with inrush current and energy efficiency requirements.
Both universal and single range AC inputs offer varying benefits depending on the product application, country of deployment, economics, electrical requirements and target market. The choice of which AC input range to go with is based predominately on these factors. Typically for high volume production, NetBit recommends a single range design as being the most cost-effective solution.
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