FAQ: Frequently Asked Questions About DC/DC Converters

Yes, thanks to the CC/CV charging characteristic our converters work as fully-fledged chargers for batteries and supercapacitors. They charge with constant current up to the end-of-charge voltage and then hold it constant. Conversely, our buck-boost converters make optimal use of the energy stored in batteries and supercaps: even as the storage voltage drops significantly, they keep delivering a stable output voltage.

Yes, our converters are permanently no-load and short-circuit proof. Under overload or short circuit they limit the output current to a safe value (CC behavior) instead of shutting down or being damaged. A thermal shutdown additionally protects the device: if the case temperature exceeds the shutdown threshold (e.g. +90 °C), the converter deactivates and restarts automatically once the temperature has dropped.

Yes, our DC/DC converters are REACH and RoHS compliant. The corresponding declarations are available for download on the "Standards and Certifications" page. If you have questions about individual substances or need customer-specific declarations of conformity, our team is happy to help.

For series products from stock: no. For build-to-order (BTO) and custom converters, initial manufacturing costs as well as development and project costs may apply – depending on the device and the scope of changes. From an order quantity of 25 pieces these are reduced to a minimum. We always list one-time costs transparently and separately in the quotation, so you have full cost control.

Of course 🙂 You too?

Yes. Many of our converters drive practically unlimited capacitive loads (datasheet: "infinite") and are suitable for active loads and parallel connection of multiple units. An integrated soft start ramps up the output voltage in a controlled way and reduces inrush currents – upstream fuses will not trip. Models with an internal decoupling diode (suffix "E") can be connected directly in parallel or in redundant configurations.

Yes. We supply series products from stock without a minimum order quantity, and we even develop and deliver custom converters from quantity one. Only project-specific build-to-order devices carry a minimum order quantity (MOQ), because small batches cause increased production costs – from 25 pieces, initial costs are reduced to a minimum. We gladly accept prototypes and sample orders on request.

Yes, we implement railway certifications flexibly on customer request – including EN 50155 (railway applications), EN 45545 (railway fire protection), EN 61373 (shock and vibration) and EN 50121-3-2 (railway EMC). Our fully potted, vibration-proof converters with wide-range input are structurally suited for rail-based transport systems, cableways and mountain railways.

Yes, we develop power electronics beyond DC/DC converters – from circuit design through prototyping to series production. On request we deliver as white label without Demke branding, so you can market the solution under your own brand. Our services also include power electronics forensics: analyzing failures and weaknesses of existing electronics.

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.

Yes, custom DC/DC converters are one of our core competencies – starting from quantity one. We realize 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 special requests for connectors, cables, housings and mounting. Send us your specifications via the inquiry form.

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.

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.

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.

Fastest directly from us: via the inquiry form on the product page, by e-mail to info@demke-electronic.com or by phone at +41 71 511 34 00 (Mon–Thu 8:30–16:00, Fri 8:30–12:00 CET). Tell us the item number or your requirements, quantity and target date – you will receive a quotation promptly. We ship worldwide to professional equipment manufacturers and industrial customers.

Four key questions lead to the right converter: (1) Input voltage range – which source, how much does it fluctuate? (2) Output voltage and maximum output current or power? (3) Isolation required or not? (4) Environment – temperature, humidity, vibration, protection class? With these parameters you can find the right device via our product filters, or use the configuration form and we will propose the optimal solution.

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

With a rugged 19 V DC/DC converter connected directly to the forklift battery. Ordinary laptop power supplies fail due to fluctuating battery voltages and vibration. Our 19 V converter (e.g. DC-Converter 145-19-SD) covers 24 V, 36 V, 48 V and 80 V forklift batteries and powers mobile IT equipment reliably – even during voltage dips when lifting or accelerating.

Depending on the DC/DC converter, different control inputs are available for externally switching the converter on or off or for selecting a different output voltage.

SD – Shutdown: The converter is enabled when the SD pin is open or High. Pulling the SD pin Low or connecting it to the negative input potential switches the converter off.

ON – Enable: The converter is disabled when the ON pin is open or Low. To switch it on, the ON pin must be pulled High or connected to the positive input potential.

SH – Switch High: On appropriately equipped products, the SH pin is used to select a product-specific output voltage setting. Its exact function depends on the individual converter.

Switch High example:

On the 757-27-SDB4, the output voltage is 29 V when the SH pin is Low. When the SH pin is open or High, the output voltage is 27 V. 

In three steps: (1) Contact us in writing before shipping and request an RMA number – returns without prior approval may be sent back unexamined. (2) Include a precise fault description. (3) Pack the device securely for transport and ship it with sufficient postage. After inspection we will inform you about repair, replacement or credit. Please report visible defects within 7 days of receiving the goods.

Depending on model and operating point, our DC/DC converters achieve efficiencies of up to 99%. Efficiency is the ratio of output power to input power, measured directly at the converter terminals. In practice, high efficiency means less waste heat, smaller enclosures, longer battery runtime in mobile systems and longer electronics lifetime. Values at full load, 50% load and 10% load are listed in every datasheet.

Series products from stock (labeled MTS – Make to Stock in the product filter) are available at short notice, usually within 6 weeks. Build-to-order devices (BTO) and custom converters are planned with you on a project basis; we state the binding delivery date in the quotation. For ongoing series demand, framework agreements with call-off quantities secure your supply.

Don't worry: for most discontinued devices (EOL – End of Life), improved successors with equal or better specifications are already available. We advise you on suitable replacement types, support the requalification of your application and, on request, arrange a last-time buy for your remaining demand. Just contact us with the item number of your device.

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.

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 an uncompromisingly high-quality bill of materials. In addition, every single device is 100% tested before delivery; more than 99.5% operational reliability has been proven in the field.

No derating means the converter delivers its full rated power across the entire specified temperature range from −40 °C to +85 °C – with no power reduction in heat or cold. Many standard converters must be throttled above roughly 50–60 °C ambient, forcing you to oversize them. Demke converters deliver up to 1200 W even under extreme conditions, so oversizing is unnecessary.

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.

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.

Galvanic isolation means the input and output circuits are completely electrically separated – energy is transferred via a transformer. This protects sensitive electronics from interference, prevents ground loops and increases safety. Our isolated converters achieve insulation strengths of e.g. 2100 VDC between primary and secondary side. Non-isolated converters share a common reference potential but are more compact and cost-effective.

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.

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.

IP69K is the highest protection rating of ISO 20653 and stands for dust-tightness plus resistance to high-pressure and steam-jet cleaning with hot water. Demke converters achieve this through an aluminum housing with full polyurethane potting and sealed cable entries. This makes them resistant to water, dirt, vibration and pressure – ideal for mobile machinery, construction equipment, agricultural technology, railway applications and food-industry areas with steam cleaning.

That is exactly what our converters are built for: the ultra-wide-range input tolerates static deviations of ±30% and more from nominal voltage. Buck-boost models keep the output stable even when the input drops below the output voltage – during cranking, lifting or with an aging battery. An undervoltage lockout protects the battery from deep discharge by shutting the converter down below a defined threshold.

CC/CV stands for Constant Current / Constant Voltage. In normal operation the converter regulates the voltage (CV); under overload it limits the current to a defined value instead (CC). This characteristic turns our DC/DC converters into fully-fledged battery chargers: a depleted battery is first charged with constant current until the end-of-charge voltage is reached – without the converter shutting down or blowing a fuse.

A DC/DC converter is an electronic device that converts one direct (DC) voltage into another, higher or lower DC voltage – for example, 80 V from a forklift battery into a stable 24 V for the on-board network. A complete Demke Electronic DC/DC converter includes not only the power stage but also the control loop, power switches and EMI filters, so the output voltage is delivered stable, low-noise and compliant with EMC standards.

A wide-range input allows a DC/DC converter to operate stably over a very large input voltage range – at Demke up to a ratio of 1:10, e.g. from 12 V (lead-acid) to 120 V (lithium). A single converter thus covers 24 V, 48 V and 80 V vehicle platforms, dramatically reducing variant diversity, stock and effort in engineering and purchasing. Example: the DC-Converter 755-24-SD operates from 18 to 110 VDC.

A buck (step-down) converter produces a lower output voltage, a boost (step-up) converter a higher one than the input. A buck-boost converter does both: it delivers a stable output voltage regardless of whether the input voltage is above or below it. This is essential in battery applications, because battery voltage varies widely with the state of charge – for example a 24 V output from a 24 V battery that swings between 18 V and 30 V.

You need an isolated converter when input and output circuits must have separate potentials – for example to protect sensitive sensors, avoid ground loops, meet safety requirements, or comply with standards (e.g. railway). A non-isolated converter is sufficient when both circuits may share the same ground potential, such as powering controllers and terminals from the same vehicle network. If in doubt, we are happy to advise you.

Development takes place in Switzerland: Demke Electronic GmbH is based in Wil SG and has specialized in DC/DC converters since 2008. Manufacturing is carried out to ISO 9001:2015 by our long-standing production partner Elotec Fischer GmbH in Germany – Designed in Switzerland, Made in Germany. Every single device is 100% tested before delivery.

Every product page offers the complete technical datasheet as a PDF download. It contains all electrical specifications (input, output, control), thermal characteristics, EMC compliance, mechanical dimensions and the pin assignment. If you are missing a parameter or need 3D data, derating curves or application notes, contact us directly.

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.

We comply with all applicable export control, embargo and sanctions regulations. Depending on the destination country, product, recipient and intended use, additional checks or approvals may be required.

For forklifts and industrial trucks we recommend our rugged converters with ultra-wide-range input, covering all common battery voltages – 24 V, 36 V, 48 V and 80 V – with a single device. They stabilize 12 V and 24 V on-board networks for terminals, sensors and communication, are fully potted, vibration-proof and deliver full power from −40 °C to +85 °C. One converter variant serves your entire vehicle fleet.

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.

Our latest developments meet the EMC standards EN 61000-6-2 (industrial immunity), EN 61000-4-2 through 4-6 (ESD, RF fields, burst, surge, conducted disturbances) as well as EN 61000-6-3/6-4 (emission for residential and industrial environments). The DC-Converter 729-57-ON holds the automotive road approval E13-10R-05. On customer request we flexibly certify additional standards, e.g. UL or ECE.

The octopus is our guiding principle: it adapts to any environment in an instant – just like our DC/DC converters, which adapt to the most diverse voltage platforms thanks to their wide-range input. Its three hearts stand for our values: acting responsibly towards stakeholders and the environment, investing in sustainable research and development, and responding flexibly to customer needs. Strong and flexible like an octopus – power converters with heart.