Questions You Should be Asking to Avoid the Wrong Power Supply


Everyone is looking to find the perfect power supply for their project. This means it meets all required specs, fits in the budget, and works how it is supposed to. Seems simple enough. But, time and time again, we see projects failing and power supplies that do not seem to work as they should. This is usually the result of a fault made at some point in the research and design process; mainly when choosing the power supply. This white paper will take you through the top mistakes encountered when choosing a power supply, the questions to ask, and the answers that will help avoid error in the future.


1. Input Voltage Conditions
2. Load Conditions
3. Environmental Conditions
4. Installation
5. Safety
6. Conclusion

Input Voltage Conditions

Is the Input Voltage Range Correct? Is a Wider Range Needed? What is the Hold Up Time?

One of the most crucial points to consider in your power supply is your input voltage, so it is important you are choosing the correct range. The range you need will be determined by the application being used. If you choose a supply that has an input range that is not wide enough, the supply will not be able to work over the complete line voltage. Every supply has a minimum voltage that the supply is able to work at, and if the input voltage range cannot reach this minimum, the supply will shut down and fail to work.

So when should you be looking for a wide input voltage range?

High Voltage Drop: Wide input voltage ranges are typically needed in applications that have a high voltage drop in the source lines, which cause high fluctuations in the voltage at the input of the supply.

High Hold Up Time: If your supply requires a high hold up time, it means that there is a risk of it losing input power for a short amount of time during use. In order to keep the supply working properly, a wide input voltage range should be chosen, to allow the supply to continue to operate as the input voltage decreases.

When Universal Input is Needed: Different countries have different input voltage regulations. This means that if you know you will be using a certain supply in the US, Japan, and Europe, for example, you should be choosing a supply with the wide, universal input range of 90~264VAC so it will not fail during use.

Remember: Using a wider voltage range can reduce the need for two separate parts.

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