Power: the heart of medical electronics

Medical power supply solutions are integral to all types of medical instrumentation, from diagnostic, imaging, and monitoring equipment to home medical devices and wearables. With each equipment category presenting specific power supply requirements, the designer must make informed technology choices early in the development cycle.

• Safety considerations take priority - since medical equipment can be physically close to, in contact with, or even inserted into patients. Additionally, many medical devices are used in the patient’s home and operated by untrained users in uncontrolled environments. Designs must therefore meet the strict safety and performance standards set by the relevant regulatory agencies, such as the FDA and IEC.
• Patient safety and equipment reliability - is enhanced by features such as backup power systems, surge protection, and isolation. Reliability will also dictate design aspects such as AC-to-DC and DC-to-DC conversion topologies — multiple stages increase reliability but must be balanced against complexity and cost constraints.
• Speed-to-market demands - compress development cycles and influence the choice between discrete components and modules. MOSFETs and IGBTs are the stalwarts of electrical power engineering but the vast choice of devices can seem bewildering. Factors such as voltage levels, switching speeds, and operating temperatures will determine the behaviour of a given component and simulations may sometimes be necessary to guarantee safe and reliable performance. Special care must be taken when designing gate driver circuits for MOSFETs, and integrated gate-driver solutions are now available. Solutions such as DC-DC converters and AC-DC power supply modules can simplify system design, reduce development time, and improve overall system performance.
• Increasing miniaturisation trends in devices such as wearables and certain surgical instruments - drive a requirement for faster switching speeds and efficiencies. Newer technologies such as Silicon Carbide (SiC) are replacing silicon for applications that need higher switching frequencies and efficiencies to shrink overall form factors.

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