Power Supply Requirements for Medical Devices

June 25, 2024
Standard

Medical device manufacturers need to understand and meet many different requirements before bringing their products to market. Not only that, all of their components, including power supplies, need to meet the requirements as well. We’ll talk about some of the power supply requirements manufacturers need to consider when deciding which PSU to include in their end product.

Hi-Pot Testing

High-potential testing (hi-pot) is done to ensure insulation is sufficient enough that medical devices remain safe for operators and patients during voltage spikes and surges. IEC 60601-1 (also known as EN 60601-1) is the main international standard concerned with hi-pot testing, which depends on the patient protection features and applied part for the device.

Medical power supply standards include requirements for hi-pot potentials based on the insulation used and maximum line voltage.

Electromagnetic compatibility (EMC)

Electromagnetic disturbances can negatively impact the performance or safety of medical electrical equipment, and IEC 60601-1-2 addresses both emissions (disturbances put out by medical devices) as well as exterior disturbances. Power supplies used in medical devices also need to meet these standards, which are currently on IEC 60601-1-2 Version 4.

Leakage Current

Shock hazards most frequently stem from leakage currents, and keeping leakage levels low is one of the critical differences between medical-grade power supplies and commercial-grade power supplies.

As Class I devices, PC-based power supplies need to abide by 60601-1 standards for sufficient insulation and protective earth grounding to guard against electrical shock. Leakage current allowances also depend on how the device comes in contact with the patient or operator.

While power supplies shouldn’t ever be in direct contact with the patient, accessories that are connected to devices that are connected to patients are required to meet the same leakage current standards. Did you know that commercial-grade power supplies allow up to 20 times the leakage current compared to medical-grade?

Many other standards are outlined in IEC 60601-1, which was revised to Version 3.2 in December 2023. Any medical electrical equipment and systems that are used to monitor, diagnose, or treat a patient, or compensate or alleviate the impact of a disease, illness, or disability fall under the IEC 60601 standards. This includes all components that make up the device.

Isolation

Isolation transformers must be used in medical-grade power supplies to isolate the input power from the output power. This can protect patients and operators should voltage spikes or line transients occur.

MOOP / MOPP

Isolation is one part of a bigger set of requirements for medical devices called means of protection, which consists of means of operator protection (MOOP) and means of patient protection (MOPP).

Based on the type of device and how it is being applied to the patient’s body, manufacturers need to understand and fulfill requirements for grounding, insulation, isolation, overcurrent protection, warning labels, residual current devices (RCDs), personal protective equipment (PPE), and non-conducting floors.

EMI/RFI Suppression

In addition to leakage current controls, medical devices should have built-in filters to suppress radio frequency interference (RFI) and electromagnetic interference (EMI).

Output Voltage and Current

Dependability is paramount. Medical-grade power supplies need to provide a stable output voltage and meet the specific needs of the medical equipment they are powering.

The level of output voltage required depends on the size of the device and its computing power, but this post has information on our power supplies and their output voltages.

Quality Management

While not required, ISO 13485 is an international standard that provides guidelines for organizations to create and maintain a quality management system (QMS) process. Applying the best practices outlined in this standard with all components can help manufacturers meet FDA and MDR requirements and get their products to market faster.

Environmental Conditions

Another variable medical devices have to account for are the environmental conditions where they will be operating. Hospitals, home care settings, and clinics all have different environmental conditions, such as vibration, moisture, and dust, that devices will need to withstand.

Reliability

Reliability is also expressed in mean time between failures (MTBF), the average amount of time between repairable product failures. Product failures can happen due to environmental conditions or failures in specific system parts.

Physical Requirements

Your device will also come with specific physical requirements a power supply needs to fulfil. The power supply manufacturer you choose should be able to accommodate the output cables you need, allowing you to have some level of customization over your PSU without having to build one from scratch.

Understand what standard cables a manufacturer offers, as well as the customizations they can provide. For example, RAM Technologies has seven standard output cables in different lengths:

4-Pin ATX + 12V
12 + 4-Pin PCle 12VHPWR Cable
Dual SATA Connectors Cable
20 + 4-Pin ATX Main Power Cable
6 + 2-Pin PCle Power Cable
Dual 4-Pin Connectors Peripheral Cable
8-Pin EPS 12V Power Cable

You’ll also likely have size requirements for your power supply. You want a small form factor PSU for a small device, for example, but the most important thing to consider is how your build size and the amount of power your need will determine the size of your PSU. Also, chances are good that your wattage requirements aren’t as high as you think.

While this isn’t an exhaustive list of power supply requirements, these are some basic factors medical device manufacturers need to understand and analyze when choosing the PSU that will work best for their product. Our PC-based medical-grade power supply units can meet these requirements and more, making the road to approval that much easier for our customers. If you have questions about specific power supply requirements we may not have covered here, or want to know more about our options and customizations, contact us today.

RAM Technologies’ power supplies are 60601-1 3.2 certified. When you’re designing your medical device and need help with a PSU, contact us for details.