Switching power supplies – find manufacturers and suppliers

Switching power supplies are electronic power supplies that convert and regulate electrical energy not linearly, but by quickly switching semiconductor switches (usually transistors) on and off.

In contrast to linear power supply units, the power loss is greatly reduced as the power semiconductors are predominantly operated either conducting (on) or blocked (off). Today, switched-mode power supplies are the standard in almost all areas of electronics - from chargers to industrial systems and servers.

Below you will find the functionality and types of switching power supplies, their use and areas of application as well as their advantages and disadvantages and challenges to be aware of:

How switching power supplies work:

The operation of switching power supplies can be divided into several successive steps:

1. Input rectification:
   Alternating voltage e.g. 230 V AC is rectified.
   The result is a pulsating direct voltage.
2. Intermediate circuit:
   Smoothing of the DC voltage using capacitors.
   In power supply units with power factor correction (PFC), the current flow is already optimized here.
3. High-frequency switching:
   A transistor, MOSFET or IGBT, switches the DC voltage with frequencies between approx. 20 kHz and several 100 kHz.
   This produces a high-frequency alternating voltage.
4. Energy transfer and voltage adjustment:
   the voltage is stepped up or down via inductors or transformers.
   High frequency allows small, lightweight components.
5. Secondary rectification and filtering:
   The high-frequency alternating voltage is rectified again.
   Filters smooth the output voltage.
6. Regulation:
   A feedback loop measures the output voltage.
   The pulse width or switching frequency is adjusted to provide a constant voltage or current.

Important types of switching power supplies:

Non-isolated topologies:
These power supplies have no electrical isolation between input and output.

1. Buck converter:
   Reduces a DC voltage to a lower level.
2. Boost converter:
   Increases a direct voltage.
3. Step-up and step-down converters (buck-boost, SEPIC, Ćuk):
   Can both increase and decrease the voltage.

Typical applications are battery devices, DC/DC converters and internal power supplies.

Galvanically isolated topologies:
Here the energy is transmitted via a transformer, increasing safety and flexibility.

1. Flyback converters:
   Simple design, ideal for low to medium power. Frequently used in chargers and plug-in power supplies.
2. Forward converter:
   Better efficiency than flyback, but more complex. Used in industrial electronics.
3. Push-pull converter:
   Two switches drive the transformer alternately. Suitable for medium power levels.
4. Half-bridge and full-bridge converters:
   Very high outputs, good efficiency. Typical for server power supplies, welding equipment, industrial systems.

Mains vs. DC/DC switched-mode power supply units:

1. AC/DC switching power supplies:
   Convert mains voltage into direct voltage. Examples: Laptop power supplies, LED drivers, power supplies for household appliances.
2. DC/DC switched-mode power supply units:
   Convert direct voltage into another direct voltage. Typically used in vehicles, embedded systems and telecommunications.

Areas of application for switching power supplies:

Switching power supplies are almost ubiquitous:

1. Consumer goods:
Smartphones, televisions, game consoles, chargers

2. IT and data centers:
PC power supplies, servers, UPS systems

3. Industry:
Controls, automation, robotics, frequency converters

4. Medical and measurement technology:
Efficient and safe supply of sensitive electronics

5. Renewable energies
Inverters, chargers for energy storage systems

6. Vehicles and railroads:
On-board networks, DC/DC converters, charging infrastructure

Advantages of switching power supplies:

• High efficiency: Typically 80-95 % or more. Less power loss and heat generation.
• Compact design: High switching frequencies allow small transformers and coils. Low weight, particularly relevant for mobile devices.
• Wide input voltage range: Many power supply units operate worldwide, e.g. 90-264 V AC. Ideal for global products.
• Good controllability: Precise voltage or current regulation. Fast response to load changes.
• Versatility: Easily adaptable to different voltages, currents and powers. Scalable from milliwatts to kilowatts.

Disadvantages and challenges:

Despite their advantages, switching power supplies also come with challenges:

• Electromagnetic interference (EMC): High-frequency switching generates interference signals that need to be filtered.
• Complexity: Design, layout and control are significantly more demanding than with linear power supply units.
• Costs for low power: For very low power, linear power supplies can be simpler and cheaper.

Switching power supplies are highly efficient, compact and versatile energy converters that work by rapidly switching electrical power. Their different topologies allow them to be used in almost all power and voltage ranges. Despite their greater complexity and EMC requirements, their advantages clearly outweigh their disadvantages, which is why they have become an indispensable part of modern electronics.

Here you will find an overview of the most important points to consider when purchasing switching power supplies:

Purchasing switching power supplies is much more than just selecting a suitable output voltage and power. Switch-mode power supplies are safety-relevant, service life-determining and often also standard-critical components of an overall system. Wrong decisions in the procurement process can lead to reliability problems, EMC faults, approval obstacles or high follow-up costs in the field.
A well-founded evaluation therefore takes electrical, mechanical, thermal, normative and economic aspects into account in equal measure.

• The first thing to check is the voltage range in which the power supply unit is to be operated. Not only the rated voltage is important, but also the:
• Permissible voltage range. E.G. 90-264 V AC.
• Mains frequency.
• Tolerance to voltage dips, overvoltages and mains failures.
• Behavior with unstable grids or generator operation.
• Robust input ranges are particularly important in industrial environments or in emerging countries.
• The specified output power should not be permanently exhausted. Professionally considered:
• Maximum continuous power.
• Recommended derating curves.
• Short-term peak load capacity.
• Inrush current limitation and behavior during load jumps.
• A power reserve of around 20-30 % significantly increases reliability and service life.
• The quality of the output voltage is decisive for many applications:
• Residual ripple (ripple and noise).
• Control accuracy.
• Load and mains regulation.
• Transient behavior.
• Particularly sensitive electronics, sensors or communication systems react sensitively to voltage fluctuations or high-frequency noise.
• A professional switched-mode power supply should offer comprehensive protection functions, including
• overcurrent protection.
• Short-circuit protection.
• overvoltage protection.
• over-temperature protection.
• Undervoltage detection.
• The decisive factor is not only the presence, but also the behavior in the event of a fault, e.g. auto-restart, latch-off.
• The required insulation class depends on the application. The following must be tested:
• Insulation voltage.
• Creepage and clearance distances.
• Protection class (I, II or III).
• In medical, industrial and building technology, clean electrical isolation is absolutely essential.
• Depending on the area of application, different standards must be met, for example
• IEC / EN 62368 (audio, IT, communication)
• IEC / EN 60601 (medical technology)
• IEC / EN 61558 (transformers and power supply units)
• A professional purchasing department checks whether the certificates are up to date and valid for the target market.
• Switch-mode power supplies are a frequent source of electromagnetic interference. The following are relevant:
• Compliance with EMC limit values.
• Conducted and radiated emissions.
• Harmonics and power factor.
• An integrated PFC (Power Factor Correction) is often mandatory for higher outputs and also improves network compatibility.
• For international use, country-specific requirements must be met, such as
• CE, UL / cUL, UKCA, CCC. as well as other regional test marks.
• Missing approvals can considerably delay market launches.
• The power supply unit must fit the system mechanically:
• Open circuit board, closed housing or top-hat rail mounting.
• Dimensions and weight.
• Mounting type and position.
• Connectors, terminals and strain relief.
• Ease of installation is an important cost factor, especially in series devices.
• The thermal design is decisive for the service life:
• Permissible ambient temperature range.
• Derating at higher temperatures.
• Natural or active cooling.
• Air flow requirements.
• A power supply unit that is permanently operated close to the maximum temperature will age significantly faster.
• The quality of critical components is crucial:
• Electrolytic capacitors (temperature and lifetime class).
• Power semiconductors.
• Transformers and chokes.
• Although high-quality components increase the purchase price, they significantly reduce failure costs in the field.
• Manufacturer information on the mean time between failure (MTBF) should be realistic and comprehensible. Also important:
• Reference projects.
• Long-term availability.
• Known failure modes.
• A proven product is often more valuable than a technically impressive but new design.
• Manufacturer, supply chain and service. To be evaluated:
• Technical support.
• Documentation and application notes.
• Response times for queries.
• Willingness to make customer-specific adaptations.
• A competent manufacturer is a strategic partner, not just a supplier.
• Long-term availability is crucial, especially for series products.
• The purchase price alone is rarely the most important criterion. Consideration should be given to
• Energy efficiency.
• Downtime costs.
• Service costs.
• Certification and integration costs.
• A slightly more expensive power supply unit can be significantly cheaper over the product life cycle.
• For product families, it is advantageous to choose power supply units that:
• Cover multiple voltages.
• Can be switched in parallel.
• Offer optional functions.
• This simplifies warehousing and product maintenance.

Professional purchasing of switching power supplies requires a holistic approach that goes beyond technical data sheets. In addition to electrical parameters, conformity to standards, protective functions, thermal design, service life, manufacturer expertise and long-term economic consequences are decisive factors.
A systematically selected switching power supply increases the reliability of the overall system, reduces development and failure costs and contributes significantly to the market success of a product. A structured and forward-looking approach to purchasing avoids compromises later on - and expensive surprises in the field.

Switching power supplies can be purchased from various suppliers. Comprehensive information about manufacturers and suppliers of Switching power supplies from all over the world can be found on Exportpages.