Topic: Switching power supplies (SMPS) — high efficiency, custom form factor

Every SMPS datasheet claims high efficiency. Very few tell you the number at the load point you actually run at.

We supply switching power supplies into continuous-operation industrial equipment, and this is the most common gap between what buyers assume and what they get.

Efficiency is a curve, not a number

A supply that's 92% efficient at 80% load may be considerably worse at 20% load. For equipment that idles most of the day and peaks briefly, the operating-point efficiency is what actually determines heat, enclosure temperature and long-term reliability.

Ask for the efficiency curve, not the peak figure. A supplier who can't produce one is telling you they haven't characterised the product.

Continuous operation is a different requirement from peak operation

"Industrial" equipment often runs 24/7 for years. That changes the design priorities:

- Component derating must be conservative — running a capacitor near its rating is fine in a lab and fatal in year three.

- Thermal design must assume worst-case ambient, not 25°C.

- Protection must include over-voltage, over-current and thermal shutdown with defined behaviour on recovery.

A supply that performs well in a demo and fails in continuous service is not a bargain at any price.

The enclosure is part of the product

In industrial settings, the SMPS is often the component that must survive dust, vibration, temperature swings and, occasionally, misuse. Form factor — open frame, enclosed, DIN-rail, potted — determines where it can be used at all. Custom form factor is frequently the difference between a supply that fits the machine and one that forces a redesign.

Compliance follows the market

CE, UL, FCC, RCM and others apply depending on where the equipment ships and what it connects to. For equipment sold into multiple markets, specifying a compliance set early prevents an expensive re-test later — and sometimes prevents a design change that could have been avoided.

Two details trip people up routinely. First, a supply certified for one market is not automatically acceptable in another, even when the electrical design is identical — the test regime and the documentation differ. Second, the compliance obligations often attach to the end equipment, not the power supply alone, which means the supply's characteristics (leakage current, emissions, isolation) feed directly into the equipment's approval. Getting this sequence wrong can invalidate an otherwise complete certification.

What "high efficiency" should actually mean to a buyer

A buyer should care about efficiency for three concrete reasons, none of which is the marketing number:

- Heat: every percent of loss becomes heat inside your enclosure, which shortens the life of everything around it, not just the supply.

- Enclosure rating: lower loss means a smaller, cheaper or sealed enclosure becomes viable — sometimes the whole reason a product can be made smaller.

- Running cost and standby: for equipment that runs continuously, small efficiency differences compound over years of operation.

Notice that every one of those is an operating-point question, not a peak-number question. That's why the curve matters more than the headline.

The reliability question nobody asks early enough

Mean time between failures, capacitor selection, and derating philosophy are unglamorous — and they determine whether a supply survives year three of a 24/7 deployment. Electrolytic capacitors are usually the limiting component; their rated life is defined at a specific temperature, and halves for roughly every 10°C of additional heat. A supply that runs 10°C hotter than necessary has half the capacitor life, independent of anything else on the datasheet.

Conservative derating is not over-engineering. In continuous-operation industrial equipment, it's the difference between a component and a consumable.

How we approach custom SMPS specification

1. Characterise the real load profile — idle, typical and peak durations.

2. Set efficiency targets at the operating point, not the headline.

3. Define the environmental envelope — ambient, airflow, contaminants, vibration.

4. Fix the form factor, derating policy and compliance set against the target market.

5. Confirm the reliability expectations for the duty cycle the equipment actually sees.

We supply high-efficiency switching power supplies with custom form factors for continuous-operation equipment, defined together with the client against the real duty cycle. If your current supply runs hot, fails early, or doesn't fit the enclosure it needs to fit, the specification is usually where the answer is hiding.