Power
Figure 2: Telecommunications systems can benefit from the use of isolated DC-DC converters. Source: photostockatinat/
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The non-isolated advantage While isolation is critical in certain scenarios, it is often an unnecessary and costly addition. In some applications, a non-isolated converter is the superior choice, offering significant advantages in performance, size, weight, power, and cost (SWaP-C). In many systems, the isolation decision is made at the architectural level. A popular approach is the distributed power architecture (DPA). In a DPA, a single, centralised AC-DC or high-power DC- DC converter provides the main safety isolation from the AC mains and generates a regulated intermediate DC bus voltage (e.g., 24 V or 48 V). Because this front- end converter has already provided the necessary safety isolation for the entire system, downstream converters usually do not need to be further isolated. This allows designers to use small, highly efficient, and low-cost non-isolated converters placed physically close to the components they are powering, leveraging the strengths of both converter types.
For applications where SWaP-C is the primary design driver, non-isolated converters are the clear choice. The main reason for their advantage is the elimination of components, such as the isolation transformer. Electrical spacings required by various safety standards increase with the maximum voltage present in the design. Often, circuits that can accept a non- isolated power topology operate at lower maximum voltages, resulting in smaller electrical spacings and a more compact design overall. This makes non-isolated converters the default solution for battery-
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powered mobile devices, commercial drones, autonomous mobile robots, and commercial aerospace applications where every gram and cubic centimetre counts. Non-isolated converters also offer superior conversion efficiencies. By removing the transformer and its associated losses, efficiencies can reach 97 per cent or 98 per cent. High efficiency means less energy is converted to heat within the power system, simplifying thermal management and improving system reliability. These higher efficiencies also extend battery life in battery-powered applications.
From a design standpoint, non-isolated topologies offer a powerful toolkit. Common topologies in this class are the buck (step- down) and boost (step-up) converters. For ultimate flexibility, particularly in battery- powered systems where the input voltage varies widely, the four-switch buck-boost converter can operate as a buck or boost converter as needed, ensuring a stable output voltage across the entire battery discharge cycle.
Many non-isolated converters are designed with very wide input and adjustable output voltage ranges. This allows a single part number to be used across multiple products or to generate various output rails, simplifying the bill-of- materials (BOM), streamlining procurement, and accelerating development. In any system where the input source and the load already share a common ground, the added cost and complexity of an isolated converter provide little to no benefit, making a non-isolated topology the logical and most efficient choice.
Figure 3: A swollen smartphone battery highlights the importance of efficient power conversion to minimise heat in compact battery-powered devices. Source: cabuscaa/
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A framework for decision-making There is no single “best” solution between isolated and non-isolated DC-DC converters; the optimal choice depends entirely on the specific needs of the application. A logical framework for this decision is as follows: ● Is safety isolation mandated? If the system is powered from a hazardous voltage or must comply with standards such as IEC 60601-1, then galvanic isolation is required.
● If isolation is required, where is it best placed? For systems with multiple output rails, a DPA is often the superior choice. A single, centralized isolated converter can provide the primary safety barrier, allowing the use of smaller, more efficient non-isolated converters for the final voltage conversion steps.
● Are there functional needs for isolation? If the system does not require
safety isolation, consider whether it is necessary to break a ground loop or generate an inverted voltage rail. If so, an isolated converter may be a better choice.
● If no to all of the above, default to non- isolated. If there are no mandatory safety or specific functional requirements for isolation, a non-isolated converter should be the default choice due to its advantages in efficiency, power density, size, weight, and cost.
Ultimately, power system design means correctly identifying and prioritising the most critical performance parameters for the end application. That makes the isolation decision a strategic rather than a purely technical choice.
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Components in Electronics September 2026 37
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