The RECOM Three Year Warranty – A Guide to the Essentials

Part of the answer lies in past experience with similar product families that use the same type of construction and share common components. For instance, we know that the RMA (Return Merchandise Authorization) rate for some series is very low. The R1S series, for example, has less than one RMA per million pieces sold. When RECOM released a similar 1W product (R1SX) sharing the same topology and QC procedures, but with an improved automated manufacturing process, the demonstrated reliability of the original 1W design could justify the same warranty period for the new lower-profile 1W series.

Another way to predict product reliability is by calculating the MTBF (Mean Time Between Failures). This statistical analysis sums the reliabilities of all individual components in a converter and applies acceleration factors that could influence overall reliability, such as Environmental Stress (temperature extremes, shock and vibration, high humidity), Functional Stress (component interactions, poor tolerances, on/off switching cycles), and Maturity (well-known and tested design versus a new approach). One reference method is the US Army’s Military Handbook – Reliability Prediction of Electronic Equipment, known as MIL-HDBK-217F, which provides historically demonstrated reliability figures for various component types. The calculated MTBF can reach a million hours or higher.

An MTBF of a million hours does not mean the converter will survive 114 years. MTBF is a statistical measure of how reliable a product is over its lifetime, which is governed by wear-out mechanisms. The correct way to interpret an MTBF figure is to work backwards from the desired failure rate. If it is acceptable for 1% of converters to fail after three years of constant use, the required MTBF level is:


For example, the R1SX product has an MTBF of over 21 million hours at room temperature, giving a statistical failure rate of 0.125% over three years of continuous operation, or an annual failure rate of one converter out of approximately 2,400 pieces.

A lower MTBF does not automatically mean that 1% of converters will fail annually. Most converters operate below 100% load during normal use. If the static load is 50%-70% of maximum rated load, stress is reduced, MTBF increases, and fewer parts fail each year. Operating the converter only during the workday further reduces total hours and annual failures. Conversely, “24/7 always-on” operation stabilizes internal temperatures and eliminates stress from power cycling, also enhancing reliability. The calculated MTBF reflects worst-case, full-load continuous operation. Therefore, RECOM offers its standard three-year warranty even for product series with calculated MTBF figures below one million hours, based on additional testing and evaluation (see next chapter).

The three-year warranty can be justified by decades of manufacturing experience and understanding of how converters are used. But how can we be confident about a completely new product with no equivalent production FMEA data, no market feedback, and a novel production process? Four techniques address this: DVT, PVT, HASS, and HALT testing.

Design Verification Testing (DVT) checks that every component operates within datasheet limits under actual conditions. For example, if a resistor or diode has a maximum rated temperature of 125°C, design rules keep it below 115-120°C in worst-case operation (full load at maximum ambient temperature) to maintain safety margins. Capacitor lifetime depends on voltage and ripple current, ideally not exceeding 70% of maximum rating. Electrolytic capacitors are often the weakest link, but derating (effectively over-designing) can achieve calculated lifetimes over 20 years with high product reliability. Similar rules apply to active components and transformer core temperatures under full load. DVT ensures that safety margins are maintained under extremes of temperature, voltage, and current.

Production Verification Testing (PVT) takes production samples to verify performance against DVT design limits. RECOM typically tests at least 50pcs of each new converter to ensure measurement accuracy, generating average and maximum deviation figures for efficiency, regulation, and output accuracy for the datasheet. This pre-qualification is repeated for different input/output combinations to analyze the product series realistically. Thousands of test conditions are automated by RECOM’s Test and Evaluation Laboratory, accelerating data collection and graph generation.

In addition to electrical testing, climate chambers perform Highly Accelerated Stress Screening (HASS). Long-term tests at extreme temperatures, temperature cycling, or combined high heat and humidity under varying operating stresses (maximum/minimum input voltage, full load, power cycling) accelerate aging effects and simulate years of continuous operation within 1,000 hours.


RECOM also uses an in-house HALT (Highly Accelerated Life-Time) chamber. This subjects devices under test (DUTs) to extreme temperatures and rapid temperature changes (liquid nitrogen can rapidly cool DUTs) while simultaneously shaking parts on a random vibration table. HALT identifies design weaknesses that could reduce product lifetime or reliability by testing to failure under combined stress, exceeding datasheet limits, unlike HASS, which remains within operating limits.


Acceleration stress factors include vibration, thermal cycling, high humidity, over-voltage/over-current, and other applied stresses. Combined stress environments, such as vibration under temperature cycling, compress time-to-failure. Studies show around 70% of failures can be detected with mechanical stress (all-axis vibration) combined with temperature stress, calculated as:

Where D is accumulated fatigue damage, n is the number of stress cycles, and σα is mechanical stress with an exponential factor depending on vibration severity. RECOM also uses two shaker tables delivering programmable sinusoidal vibration profiles with displacement and g²/Hz accelerations for products up to 130kg.


Mechanical stress testing exposes weaknesses in new designs, and combined with HASS and PVT results, supports justification of a three-year warranty for existing products.

RECOM designs efficient, cost-effective, and reliable AC/DC and DC/DC electronic converters, whether off-board or board-mounted. While all manufacturers claim reliability, RECOM supports this with a minimum three-year warranty on all products. Extensive verification testing, production QC, and accelerated stress screening ensure high product reliability, long operational lifetimes, and datasheet accuracy based on documented test protocols.