Figure 1: The isolation transformer breaks the current path from neutral to Earth, so the current will not flow through the user even if the user’s device or system is accidentally connected to the exposed case. Image source: Quora
Improvements in battery technology along with advances in low-power circuitry have made portable, battery-powered systems a viable option for many designs, but in applications such as medical and home healthcare, battery-only, untethered operation is not feasible, practical, or even desirable. Instead, the equipment must operate directly from an AC line or have access to an AC outlet to ensure reliable operation when the batteries are low. For these cases, the AC/DC supply must provide the usual power supply performance with respect to
voltage and current output, static and dynamic regulation, as well as fault and other protection features. In addition, basic power supply performance is not the only concern for medical systems designers. Various regulatory standards exist – and have recently been upgraded – which add additional mandates for less-obvious performance issues such as galvanic isolation voltage, leakage current, and two means of patient protection (2×MOPP). These are in place to ensure that the equipment which the supply
is powering does not put the operator or patient at risk even if there is a failure in the supply or the equipment. The combination of performance, reliability, and standards requirements, as well as cost and time to market pressures, make designing a power supply from scratch a challenging proposition. Instead, designers need to sift carefully through an array of ready- made options for the optimum solution. This article looks at applications for AC/DC supplies in medical- instrument environments, reviewing the critical regulatory standards for these supplies. It then introduces example supplies from CUI Inc. and discusses their respective characteristics and how they can help solve the medical system power supply challenge.
Select the right AC/ DC power supply to meet unique medical requirements
Various regulatory standards exist – and have recently been upgraded – which add additional mandates for less-obvious performance issues such as galvanic isolation voltage, leakage current, and two means of patient protection (2×MOPP).
Written by Bill Schweber
we get technical
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