Every so often we get asked if we offer a small (fanless, industrial, rugged etc) PC with an integrated AC power supply.
We get it – lugging around a AC-DC adapter is annoying and in a way it’s another point of failure. Desktops seem much cleaner – there is just one plug for the AC cord that goes to the wall. So why can’t smaller industrial PCs have that?
Well, there is a good reason for this apparent injustice.
Motherboards and CPU architecture is built on DC, typically 12 or 19V. So at the end of the day, your PC can’t run on AC anyway, it needs the alternating current from the mains to be converted to direct current.
A desktop has enough space inside the chassis to enclose an integrated power supply, whereas an industrial fanless unit may not.
But a desktop isn’t built to just be able to have an integrated AC supply, it also needs a different kind of power supply – typically when running desktop processors and GPUs, these require far more power than the industrial embedded systems. An external AC adapter is limited by the DC connector’s current-carrying capabilities so when a system gets above around 300 Watts, you need more 12V rails to deliver that kind of current.
Now, on top of the fact that embedded rugged systems typically don’t need the amount of current an integrated psu can deliver, there are other good reasons to use an external adapter for these:
🔧 Reliability in Harsh Environments: Internal AC power supplies are more vulnerable to failure from heat, vibration, moisture, and dust which are common in industrial settings
📏 Compact, Sealed Designs: Fanless and IP67-rated enclosures require minimal internal components and no ventilation - bulky AC PSUs and their heat output don’t fit this design philosophy
🔋 Direct Integration with DC Power Systems: Many industrial environments - like vehicles, solar-powered sites, and factory automation - already run on DC. A DC input simplifies integration
🔥 Reduced Heat Generation: Eliminating an internal AC-DC converter cuts down on internal heat, supporting thermal efficiency and long-term reliability in sealed systems
⚡ Flexible Voltage Input: Industrial PCs often support wide-range DC input (e.g., 9-48V), enabling use in varied power environments without converters
🛡️ EMI and Safety Compliance: External AC adapters can more easily be shielded or certified for EMI/EMC, whereas internal AC PSUs complicate rugged compliance with standards like MIL-STD-810 and IP67
🧰 Simplified Maintenance & Customization: External power supplies are easier to replace or upgrade, supporting field serviceability and customer-specific configurations
So TL;DR: desktop systems have an integrated AC psu because:
- They have the space for it
- They require more power that an adapter can’t always provide
Embedded systems use an external AC-DC adapter because:
- They need less power
- There is less space inside for an integrated psu
- It makes it easier to cool them, make them fanless, and comply with rugged certifications