DC/DC-Converters
Answers about DC/DC converters

FAQ: Frequently Asked Questions About DC/DC Converters

Whether it is input voltage, galvanic isolation, efficiency, CC/CV or the right design for your application: here we answer common technical questions about DC/DC converters, how to choose them and how they are used. The information is intended for engineers, designers, technical buyers and anyone who needs a reliable power supply for vehicles, machines and demanding electrical systems.

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From the basics to specific applications: here you will find answers to frequently asked questions about the selection, function and use of our DC/DC converters.

What Is a DC/DC Converter?

A DC/DC converter is an electronic device that converts a DC voltage into another, higher or lower DC voltage – for example, 80 V from a forklift battery into a stable 24 V for the onboard power supply. A complete DC/DC converter from Demke Electronic includes not only the power stage, but also control circuitry, power switches and EMI filters. This ensures a stable, low-noise and standards-compliant output voltage.

A step-down converter (buck) generates a lower output voltage, while a step-up converter (boost) generates a higher output voltage than the input voltage. A buck-boost converter can do both: it provides a stable output voltage regardless of whether the input voltage is above or below it. This is particularly important in battery applications, as the battery voltage can vary significantly depending on the state of charge – for example, a 24 V output from a 24 V battery whose voltage varies between 18 V and 30 V.

Galvanic isolation means that the input and output circuits are electrically isolated from each other – power is transferred via a transformer. This protects sensitive electronics from interference, prevents ground loops and enhances safety. Our isolated converters offer isolation ratings of, for example, 2100 VDC between the primary and secondary sides. Non-isolated converters (“without isolation”) are more compact and cost-effective, but share a common reference potential.

You need an isolated converter when the input and output circuits must have separate potentials – for example, to protect sensitive sensors, prevent ground loops, in safety-critical applications or when required by standards, such as in railway applications. A non-isolated converter is sufficient when both circuits can share the same ground potential, for example when supplying control systems and terminals from the same vehicle onboard power system. If in doubt, we will be happy to advise you.

CC/CV stands for Constant Current / Constant Voltage. During normal operation, the converter regulates the output voltage (CV). In the event of an overload, it limits the current to a defined value (CC). This characteristic makes our DC/DC converters fully capable battery charging converters: a discharged battery is initially charged with constant current until the defined end-of-charge voltage is reached – without the converter shutting down or triggering a fuse.

A wide input range allows a DC/DC converter to operate reliably over a very large input voltage range. Demke converters offer ranges of up to 1:10, for example from 12 V lead-acid to 120 V lithium systems. One converter can therefore cover 24 V, 48 V and 80 V vehicle platforms. This significantly reduces the number of variants, storage costs and effort in development and purchasing. Example: the 755-24-SD DC Converter operates from 18 to 110 VDC.

No derating means that the converter delivers its full rated power across the entire specified temperature range from −40 °C to +85 °C – without reducing its output under high or low temperatures. Many standard converters have to be derated from around 50–60 °C ambient temperature, meaning they need to be oversized. Demke converters deliver up to 1200 W even under extreme conditions, eliminating the need for oversizing.

Depending on the model and operating point, our DC/DC converters achieve efficiencies of up to 99%. Efficiency describes the ratio of output power to input power, measured directly at the connection terminals. High efficiency means, in practice: less waste heat, smaller housings, longer battery runtime in mobile systems and longer service life of the electronics. The values at full load, partial load (50%) and light load (10%) can be found in each datasheet.

IP69K is the highest protection class according to ISO 20653. It provides protection against dust as well as high-pressure and high-temperature water jets. Demke converters achieve this through an aluminium housing with full PU potting and sealed cable connections. This makes them resistant to water, dirt, vibration and pressure – ideal for mobile machines, construction equipment, agricultural machinery, railway applications and food industry environments with high-pressure cleaning.

MTBF (Mean Time Between Failures) is the statistical average operating time between two failures. MTTF (Mean Time To Failure) is the average time until a device fails. Demke converters achieve MTBF values of up to 1.5 million hours, made possible by a consistently high-quality component selection. In addition, every device is 100% tested before delivery. In the field, our converters have demonstrated an operating reliability of over 99.5%.

Yes, our converters are permanently protected against no-load operation and short circuits. In the event of an overload or short circuit, they limit the output current to a safe level (CC behaviour) instead of shutting down or sustaining damage. In addition, thermal shutdown protects the device: if the housing temperature exceeds the shutdown threshold (e.g. +90 °C), the converter switches off and automatically restarts once the temperature has dropped.

The shutdown pin allows the DC/DC converter to be switched on and off externally without disconnecting the input voltage. For normal operation, the pin remains open; when activated, the converter enters standby mode and draws only a minimal quiescent current (e.g. 2.5 mA for the 755-24-SD). This is useful for energy management, ignition-switched logic or remotely switching off individual loads.

Yes. Many of our converters can drive practically unlimited capacitive loads (datasheet specification: “infinite”) and are suitable for active loads and parallel operation of multiple devices. An integrated soft start ramps up the output voltage in a controlled manner and reduces inrush currents – preventing upstream fuses from tripping. Models with an internal decoupling diode (suffix “D”) can be connected directly in parallel or used in redundant configurations.

Four key questions lead to the right converter: (1) Input voltage range – what is the source and how much does it fluctuate? (2) Output voltage and maximum output current or power? (3) Is galvanic isolation required or not? (4) Environment – temperature, humidity, vibration, protection rating? With this information, you can use our product filters to find the right device, or use the configuration form and we will suggest the optimal solution.

For forklifts and material handling vehicles, our robust converters with ultra-wide input voltage ranges are ideal, covering all common battery nominal voltages – 24 V, 36 V, 48 V and 80 V – with a single device. They provide stable 12 V and 24 V onboard power for terminals, sensors and communication systems, are fully potted, vibration-resistant and deliver full power from −40 °C to +85 °C. This means a single converter variant is sufficient for the entire vehicle fleet.

With a robust 19 V DC/DC converter connected directly to the forklift battery. Standard laptop power supplies are not designed to handle fluctuating battery voltages and vibration. Our 19 V converter (e.g. the 145-19-SD DC converter) covers 24 V, 36 V, 48 V and 80 V forklift batteries and reliably powers mobile IT equipment, even during voltage drops when lifting or accelerating.

Yes, thanks to their CC/CV charging characteristic, our converters can be used as fully capable charging converters for batteries and supercapacitors. They charge with constant current up to the end-of-charge voltage and then maintain it at a constant level. Conversely, our buck-boost converters make optimal use of the energy stored in batteries and supercapacitors: even when the storage voltage drops significantly, they provide a stable output voltage.

Yes, custom DC/DC converters are one of our core competencies – starting from a single unit. We provide unipolar output voltages from 12 V to 200 V (e.g. 13.8 V, 24 V, 27.5 V, 28 V, 29 V, 48 V, 57 V) as well as isolated converters with bipolar outputs such as ±15 V, ±24 V or ±28 V. We also implement custom requirements for connectors, cables, housings and mounting. Send us your specifications via the enquiry form.

Yes, we develop power electronics beyond DC/DC converters – from circuit design and prototyping to series production. On request, we also provide white-label solutions without Demke branding, allowing you to use the solution under your own brand. Our services also include power electronics forensics, i.e. the analysis of failures and weaknesses in existing electronics.

That is exactly what our converters are designed for: the ultra-wide input voltage range handles static deviations of ±30% or more from the nominal voltage. Buck-boost models maintain a stable output voltage even when the input voltage drops below the output voltage – for example during starting, lifting or with an aging battery. An undervoltage lockout protects the battery from deep discharge by switching off the converter below a defined threshold.

The fastest way is to contact us directly: via the enquiry form on the product page, by email at info@demke-electronic.com or by phone at +41 71 511 34 00 (Mon–Thu 8:30–16:00, Fri 8:30–12:00). Tell us the part number or requirements, quantity and desired delivery date – you will receive a quotation promptly. We supply professional equipment manufacturers and industrial customers worldwide.

MTS (Make to Stock) identifies our stock-managed standard products. These devices are manufactured regularly in series and are available at short notice, depending on current stock levels, or generally within 6 weeks. MTS products can be identified by the corresponding label in the product filter. For ongoing series requirements, we are happy to arrange framework agreements with call-off quantities.

BTO (Build to Order) means that the device is fully developed and manufactured after the order is placed. Initial production costs may apply, which are reduced to a minimum from a minimum order quantity of 25 units. Prototypes and project-specific orders are also available on request. BTO devices may still undergo changes resulting from internal validation until final approval.

MOQ is the minimum order quantity for project-specific, custom DC/DC converters. Since custom devices are manufactured exclusively for specific projects and are not kept in general stock, they have a minimum order quantity due to the higher production costs for small quantities; one-time costs may also apply. Talk to us – we can always find a solution for prototypes and pre-series production.

EOL (End of Life) identifies products that are no longer in series production or are no longer recommended for new projects. Many EOL devices already have improved successors with the same or better specifications. If you are using an EOL product, we will be happy to advise you on suitable replacements and support you with requalification.

Yes. We supply custom converters starting from a single unit and are happy to accept prototypes and project-specific orders on request. For build-to-order products, initial costs are reduced to a minimum from 25 units. For series production, we scale manufacturing through our ISO 9001-certified production partner in Germany.

Unsere neuesten Entwicklungen erfüllen die EMV-Normen EN 61000-6-2 (Störfestigkeit Industrie), EN 61000-4-2 bis 4-6 (ESD, HF-Felder, Burst, Surge, leitungsgeführte Störungen) sowie EN 61000-6-3/6-4 (Störaussendung Wohn- und Industriebereich). Der DC-Converter 729-57-ON besitzt die Automotive-Strassenzulassung E13-10R-05. Auf Kundenwunsch zertifizieren wir flexibel weitere Standards, z. B. UL oder ECE.

Yes, we can implement certifications for railway applications flexibly according to customer requirements – including EN 50155 (railway applications), EN 45545 (fire protection for railway applications), EN 61373 (shock and vibration) and EN 50121-3-2 (railway EMC). Our fully potted, vibration-resistant converters with wide input voltage ranges are already designed for rail transport systems, cable cars and mountain railways.

Yes, our DC/DC converters are REACH and RoHS compliant. The relevant declarations are available for download on the “Standards and Certifications” page. If you have questions about individual substances or customer-specific declarations of conformity, our team will be happy to assist you.

Development takes place in Switzerland. Demke Electronic GmbH is based in Wil, Switzerland, and has specialized in DC/DC converters since 2008. Production is carried out according to ISO 9001:2015 by our long-term manufacturing partner ELOTEC Fischer Elektronik GmbH in Germany – Designed in Switzerland, Made in Germany. Every device is 100% tested before delivery.

In three steps: (1) Contact us in writing before returning the device and request an RMA number – returns without prior coordination may be sent back without inspection. (2) Include a detailed description of the fault. (3) Pack the device securely for transport and ship it with sufficient postage. After inspection, we will inform you whether the device will be repaired, replaced or credited. Please report any apparent defects within 7 days of receiving the goods.

The complete technical datasheet is available as a PDF download on every product page. It contains all electrical specifications (input, output, control), thermal characteristics, EMC compliance, mechanical dimensions and pin assignment. If any information is missing or you need 3D data, derating curves or application notes, contact us directly.

Directly and without a ticketing system: by phone at +41 71 511 34 00 (Mon–Thu 8:30–16:00, Fri 8:30–12:00) or by email at info@demke-electronic.com. At Demke, you speak directly with the engineers behind your power supply – from product selection and EMC questions to field failure analysis. For project discussions, you can also book an appointment directly.

The octopus is our guiding principle: it adapts rapidly to any environment – just like our DC/DC converters, which adapt to a wide range of voltage platforms thanks to their wide input voltage ranges. Its three hearts represent our three principles: responsibility and discretion, research and development, and lean structures. Strong and flexible like an octopus – power converters with heart.

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We supply our customers worldwide directly. International deliveries are generally shipped from our production site in Germany. Customers in Switzerland are supplied directly from our Swiss warehouse.

In selected regions, we also work with carefully chosen sales partners. However, contacting Demke directly remains the easiest way to make enquiries, select products and place orders.

Yes. For regularly required DC/DC converters, we offer individual framework agreements with agreed quantities, prices, contract terms and call-off orders.

For recurring orders, we strongly recommend entering into a framework agreement. Especially for electronic components, supply shortages can lead to longer procurement and production times. By planning requirements in advance, we can schedule materials and production capacities proactively and significantly increase supply security.

The terms depend on the product, annual demand, call-off quantity and desired delivery time.

Our DC/DC converters are manufactured by our ISO 9001:2015-certified production partner. This ensures defined and documented quality processes throughout manufacturing.

Technical design, custom adaptation and project coordination are carried out in close collaboration with us. Depending on the product, the devices are tested, potted and documented in accordance with the agreed technical requirements.

We deliver within Switzerland, Germany, the European Union and, in principle, worldwide. Swiss customers are supplied directly from our warehouse in Switzerland; international deliveries are generally shipped from our production site in Germany.

Dabei beachten wir alle geltenden Exportkontroll-, Embargo- und Sanktionsvorschriften. Je nach Bestimmungsland, Produkt, Empfänger und Verwendungszweck können zusätzliche Prüfungen oder Genehmigungen erforderlich sein.

Each DC/DC converter is fully automatically tested multiple times during manufacturing. This allows electrical deviations to be detected at an early stage, before the device is fully potted and shipped to the customer.

specially with fully PU-potted assemblies, complete testing is essential because later repairs are only possible to a limited extent. Devices outside the defined tolerances are therefore removed during the production process. This helps us maintain consistent quality while reducing scrap, material use and unnecessary transport.

In principle, we supply according to the following Incoterms:

  • Within Switzerland and Germany: EXW, DAP
  • Within the EU: DAP
  • Third countries: DAP, FCA


We are happy to review alternative Incoterms individually, depending on the destination country and the requirements of the respective project.

Any further questions?

No problem. Check out our glossary or get in touch with us.

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