Isolated vs Non-Isolated DC-DC Converters: Which Do You Need?

A DC-DC converter changes one DC voltage into another. The first decision is whether you need an isolated or a non-isolated part — and it is worth getting right, because it touches safety, noise and price.

Non-isolated

Input and output share a common ground; the converter simply steps the voltage up or down (a buck, boost or buck-boost). They are smaller, cheaper and very efficient, and they are the right choice when everything sits on the same ground rail — for example dropping 24 V down to 5 V for logic on the same board.

Isolated

A transformer separates input and output, so there is no direct electrical connection between them. Choose isolated when you need to:

• Break ground loops — stop noise travelling between sections of a system.
• Meet a safety requirement — isolation barriers are often specified in industrial, medical and instrumentation designs.
• Float a rail — create an output that sits at a different potential from the input, or a negative rail from a positive one.

Isolation is quoted as a test voltage (for example 1.5 kVDC or 3 kVDC) — check it meets your standard.

A quick rule of thumb

Same ground, just need a different voltage, want it small and cheap? Non-isolated. Need a safety barrier, a floating or negative rail, or to kill a ground loop? Isolated.

Browse the DC-DC range — isolated and non-isolated, board-mount through chassis — or tell us the rails you need and we will narrow it down.