Enhancing Medical Equipment Safety: Advancing Endoscopy Technology with AC/DC Power Supplies and DC/DC Converters

Endoscopy technology faces a range of technical and safety challenges. As invasive devices, endoscopes must meet strict electrical safety standards, including leakage current regulations, while supplying power for various components such as lighting, motors, and cameras. To meet these demands, P-DUKE offers a comprehensive portfolio of DC/DC converters specifically designed to comply with Type CF standards, ensuring leakage current remains below 10µA.

Ensuring Electrical Safety in Medical Devices

The safety of medical electrical equipment is governed by two primary protection mechanisms:

1. Isolation: A protective barrier between high-voltage AC or DC power and low-voltage electronic systems connected to the patient. This principle is discussed in our case study of patient monitoring equipment.
2. Limiting Leakage Current: The leakage current that can potentially pass through a patient’s body must be strictly controlled. In industrial and household settings, leakage currents up to 30mA are permissible, but medical applications have much more stringent limits. The medical standards define three classes:
   • Type B (Body): Equipment with no patient connection.
   • Type BF (Body Floating): Equipment connected to the patient.
   • Type CF (Cardiac Floating): Equipment connected to the patient, suitable for cardiac use.

Under normal operation, the leakage current must not exceed the following limits:

The primary source of leakage current comes from the EMI filter used in AC/DC power supplies. To meet the 100µA leakage current requirement for Type BF applications, P-DUKE offers AC/DC power supplies with built-in Class B EMI filters (see Figure 1). However, meeting the more stringent 10µA leakage current limit for Type CF applications with just AC/DC power supplies would require large, cumbersome filters.

Combining AC/DC Power Supplies and DC/DC Converters

To address this challenge, P-DUKE integrates AC/DC power supplies with downstream DC/DC converters, providing an effective solution for Type CF applications. Let’s take a closer look at a real-world example.

Modern medical endoscopes are used not only for diagnostic purposes but also for minimally invasive surgeries. These devices combine advanced optics, motors, soft robotics, and high-precision mechanics. They are used inside the human body, often close to the heart and in contact with blood. As such, they must comply with the 10µA leakage current requirement for Type CF applications.

A customer sought to design a compact video endoscope featuring an LED light source, a built-in camera in the endoscope head, and small motors that control the head’s movement.

How P-DUKE’s Power Solutions Support Efficient Endoscopy Power Systems

The system consists of a central processing unit (CPU) with a microprocessor, an interface to an external video processing unit, a hospital information system, and optional external storage devices. The total power consumption is about 26W.

The endoscope requires a 5V/20W power supply to support the LED and camera, as well as a 12V/5W power supply for the small motor that moves the head through a Bowden cable.

With an overall system power consumption of around 44W, P-DUKE’s extensive range of power converters enables the creation of a highly flexible solution (see Figure 2).

P-DUKE’s Medical Power Solutions: A Key to Advancing Endoscopy Technology

The 65W MAD65 medical-grade AC/DC power supply generates a 12V bus voltage from AC power. It is an easy-to-integrate solution with a built-in Class B EMI filter, meeting the stringent requirements of 4000VAC reinforced isolation and 2xMOPP for medical devices.

P-DUKE’s extensive AC/DC power supply range, from 15W to 450W, includes products that comply with the 2xMOPP standard and have been updated to the latest medical safety certification EN60601-1 ED3.2.

P-DUKE’s downstream medical DC/DC converters generate various power supply voltages for electronic devices. With leakage currents significantly below the 10µA limit, all converters meet Type CF standards.

The 5V/20W module is used to power the microprocessor, while additional 5W/10W DC/DC converters provide isolation for all interfaces. The same 5V/20W module powers the LED and camera in the endoscope, while a 12V/5W converter drives the motor. If a 3.3V power supply is required, a small auxiliary converter can be easily incorporated.

P-DUKE’s medical power converter series simplifies the design of highly flexible solutions that meet all necessary safety standards.

Considerations for Redesign

The customer is now considering replacing the MAD65 AC/DC power supply with the new MAD50 50W series. The MAD50 occupies 25% less space (3” x 1.5”) compared to the MAD65 (3” x 2”), thereby providing additional space for other components.

P-DUKE’s advanced medical power solutions offer flexible, high-performance designs that meet the most demanding safety and power requirements for medical devices like endoscopes. With these solutions, manufacturers can continue to innovate while ensuring the safety and reliability of their devices in critical medical environments.