Different Power Supply Sizes and Why They Matter

Why Different Power Supply Sizes Matter for Different Medical Devices 

When it comes to medical devices, different power supply sizes will work for different purposes. The sizes of power supplies can affect the performance, stability, and portability of a medical device. For example, smaller medical devices that need to be more portable would also benefit from smaller power supply units. However, PSUs also need to be considered alongside performance concerns. The power supply unit needs to be large enough to support graphics processing and other performance requirements of the given medical device. We’ll talk about the most common sizes of power supply units for medical devices, what they’re used for, and what to consider when choosing the size of your power supply unit. 

ATX Power Supply Size 

ATX stands for “Advanced Technology eXtended.” This PSU started with Intel in 1995. The dimensions for an ATX power supply unit are fairly standard across the board, but can vary slightly depending on the manufacturer: 

  • 150 mm wide x 86 mm tall x 140 mm deep 
  • 5.9  in wide x 3.4 in tall x 5.5 in deep 

This is the most common power supply form factor, used mostly by larger medical devices and those that have high graphics demands. The ATX power supply size tends to have higher power outputs compared to other PSUs. For example, RAM’s ATX power supplies output up to 800 watts of power

SFX Power Supply Size

This smaller form factor power supply unit is designed for smaller medical devices. They’re more lightweight and also have smaller dimensions: 

  • 125 mm wide x 63.5 mm tall x 100 mm deep 
  • 4.9 in wide x 2.5 in tall x 3.9 in deep 

The SFX power supply form factor can also be more efficient and quieter than ATX power supplies, but it also tends to be less powerful. RAM’s maximum for an SFX power supply is 650 watts. 

Still, at this size and wattage, these PSUs can still support embedded applications in systems that are graphics-intensive. 

AT Power Supply Size 

AT power supplies were mainly popular in the 1990s and 2000s. In general, they provide between 250 and 500 watts of power. These are not used for new devices anymore, but they can be found in legacy devices. 

1U Power Supply Size 

1U PSUs are small and compact, making them good for smaller medical devices. Dimensions for a 1U PSU can vary, but common dimensions are as follows: 

  • 100 mm wide x 40.5 mm tall x 235 mm deep 
  • 3.9 in wide x 1.6 in tall x 9.2 in deep 

They are designed based on the rackmount server size and are usually used when manufacturers need to keep a medical device thin. Because of their slim profile, 1U PSUs have lower power compared to ATX and SFX power supplies. 

What to consider when choosing a power supply size 

When choosing a power supply size for your medical device, you’ll want to consider several factors. The biggest driver of power supply size is the graphics card or cards being used by the device. Each graphics card will use 100-250W of power, so the PSU needs to be powerful enough to support them. The size of the device and other power and computing needs of the device, besides graphic demands, will also play a significant role in choosing the right power supply size. 

You may also want to consider the customizability of the cables and accessories that come with the PSU when choosing both the size and the specific manufacturer for the size you need. RAM Technologies offers customization for cables and other modifications for medical device manufacturers. 

Finally, compliance needs to play a role in the power supply you choose. Even if you find a PSU at the right size, if it doesn’t meet compliance standards for medical electrical equipment, it won’t be a good fit for your device. RAM Technologies’ PC-based medical power supply units are designed with medical devices in mind, meeting all necessary compliance standards.

If you need help selecting the right size for your needs, contact us today


RAM Technologies’ power supplies are 60601-1 3.2 certified and meet 60601-1-2 EMC standards.


More Resources:

We Answer Your Power Supply Questions

5 Questions to Ask Before Buying a Medical Power Supply

How to Choose the Right Power Supply for Your Medical Device


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