Competence Library - Driver & Power Supplies

Direct parallel wiring on one constant current output is critical because current does not automatically divide evenly between LED branches. Small differences in forward voltage, temperature or cable

Drivers in suspended ceilings need air circulation, secure mounting, strain relief and service access. They must not be placed inside insulation or directly next to heat sources without verification. The tc point should re

CC/CV mix ups can be recognized by symptoms such as failure to start, immediate protection mode, flicker, uneven brightness, overheating or damaged LEDs. The first diagnostic question is: does the LED load require fixed current or fixed voltage? The datasheet, driver la

Voltage drop in LED strips is reduced by shorter cables, larger conductor sizes, multiple feed points or feeding from both ends. Especially with 24V strips with high wattage per metre, voltage drop can quickly cause visible brig

COB LEDs usually require a constant current driver with suitable current, the right voltage window and a sound thermal design. Because COBs can reach high power density, the LED module, heat sink, driver current and luminaire housing mus

Linear LED modules may require constant current or constant voltage depending on their design. Module technology, length, wiring, feed in, dimming method and mechanical installation space should therefore be checked together. For light lines,

Commissioning Casambi controlled drivers starts with electrical verification: supply, load, interface and wiring must be correct. Casambi devices are then added in the app, named, grouped and assigned to scenes or control logic. If DALI bridges are used, bu

Programmable drivers are configured, depending on the series, via NFC, DALI, software, DIP switches or a separate programming device. On site, the LED load, required output current and permitted voltage window should be clarified first. Dimming curve,

Driver lifetime depends on temperature, load, component quality, switching frequency and operating profile. It is not automatically the same as LED module lifetime. Electrolytic capacitors and thermally stresse

Efficiency describes how much of the input power is delivered as usable output power. High efficiency reduces heat losses and operating costs. Standby consumption becomes especially important when many connected d

Human centric lighting requires multi channel drivers or controllers that can change colour temperature and brightness throughout the day in a stable and repeatable way. Warm white and cool white channels must be mixed cleanly without visible step

When reading the voltage window of a constant current driver, the combined LED forward voltage at the selected current must fall within the permitted range. In a series circuit, the module voltages add up. Temperature and manufacturing tolerances change the real fo

The correct output current is derived from the LED module datasheet and checked against the required light output, thermal concept and lifetime target. A module can often be operated at several currents, but efficiency, temperature and brightness will change.

Mains voltage, SELV outputs and control wiring must be separated or suitably insulated according to protection class, datasheet and installation rules. This is not only a safety issue but also affects EMC and ser

To size a 24V power supply, the strip wattage per metre is first multiplied by the installed length. Reserve, controller losses, feed points, cable length and voltage drop are then considered. A larger power supply will not fix brightness loss at the end of

In a series circuit, the same current flows through all LED modules while the forward voltages add up. The driver must provide the required current and cover the total voltage demand within its output window. Tolerances, temperature behaviou

Zhaga Book 18 defines a standardized mechanical and electrical interface for sensor and communication modules on outdoor luminaires. D4i provides the DALI based data, diagnostics and power supply cont

Casambi controls LED drivers wirelessly but still requires a suitable electrical interface to the luminaire. Depending on the device, integration may use DALI, 0?10 V, PWM, phase cut or other variants. Casambi therefore does not automatically replace the driver, it adds or translates the control

In practice, DALI devices receive short addresses, are assigned to groups and are then linked to scenes or parameters. Before that, the bus line must work electrically: bus voltage, power supply and device count must be correct. Typical proble

The driver influences light quality through current stability, ripple, flicker, dimming curve, low end behaviour, soft start and channel consistency. Even a high quality LED module can perform poorly if the driver regulates unevenly or steps at low di

Ambient temperature affects driver lifetime, protection behaviour and available output power. A device that works without problems on a test bench may become thermally critical in an insulated ceiling or closed luminaire housing. In addition to the ta value and tc

A 0?10 V driver requires mains supply, LED output and two analogue control wires. For these control wires, polarity, current sink or current source logic and the permitted signal range are decisive. Some systems do not truly switch off at 0 V and require an additional relay

A DALI driver is connected to the DALI bus line in addition to mains supply and LED output. The DALI line is generally polarity free, but terminals, insulation, cable length, bus power and device count must fit the system. Before power up, LED load, output cur

A DALI line requires a defined bus power supply. Several bus supplies must not simply be operated in parallel unless the system explicitly allows it. Especially with D4i drivers, sensors, gateways and Casambi DALI components, it must be clear which devices prov

A suitable power reserve protects against tolerances, temperature stress and minor extensions without operating the driver too far outside its optimal working range. Designs are often intentionally not plann

Current source and current sink describe which side of the 0?10 V interface provides or loads the control signal. A current source supplies the control voltage, while a current sink pulls it down in a defined way. If two devices with the wrong

CE conformity is a manufacturer declaration that applicable EU requirements are fulfilled. It is not an independent quality mark and says little on its own about dimming quality, flicker, lifetime or project compatibility. Depending on

D4i is an extension within the DALI 2 world for intelligent luminaires. It combines DALI communication with standardized data, diagnostics and power supply functions inside the luminaire. D4i is especially relevant for outdoor luminaires, Zhaga interfaces, sensor in

Dim to warm means that colour temperature becomes warmer as the light is dimmed, creating a halogen like atmosphere. A standard single channel driver is usually not enough, suitable LED channels, an appropriate driver or controller and a coordinated dimming curve are required. It is important to know wh

The dimming curve describes how a control value is translated into perceived brightness. A linear electrical curve does not always feel linear to the human eye, because perception is not proportional to power. Logarithmic or project specific curves can therefore appear more natural. If different driver series a

EMC means electromagnetic compatibility. A driver should not disturb other devices beyond permitted limits and should itself be sufficiently immune to external interference. In addition to the device, cable routing, earthing, housing, output cable lengths, dimming and ins

Low end dimming describes how a driver behaves at very low light levels, for example below 10 percent or down to 1 percent. This is where differences between basic and high performance drivers become especially visible. Stable regulation, a smooth dimming curve, no stepping, no flicker and repeatable values across multi

Output current is the electrical current supplied by a constant current driver to the LED load. It influences luminous flux, efficiency, temperature, colour stability and LED module lifetime. A higher current does not automatically produce a better result, because thermal stress and efficiency losses can

For constant current drivers, output voltage is not a fixed project value, it results from the forward voltage of the connected LED load. The driver must be able to provide this voltage at the selected current within its permitted voltage window. With constant voltage power supplies, the output voltage is the fixed system value, s

Protection class describes the electrical safety concept of a driver or luminaire. Class I uses protective earth, while Class II relies on double or reinforced insulation. Protection class affects housing design, earthing, wiring, terminal compartments

Ripple is residual variation in output current or output voltage. It can lead to visible flicker, subtle visual discomfort or banding in camera recordings. How critical ripple is depends on the LED load, dim level, driver technology and application. In museums, retail, hospitality, studio

SELV stands for Safety Extra Low Voltage. Whether an LED output is SELV depends on the specific driver, its insulation, output voltage and marking. SELV affects luminaire construction, cable routing, protection against electric shock and separation

Standalone DALI with Casambi describes small DALI environments that can be controlled through a Casambi device without a traditional central DALI controller. This can be useful for individual rooms, retrofit solutions or

The output window describes the combinations of current and voltage within which an LED driver can operate reliably. With a programmable constant current driver, for example, a current may be selected while the resulting LED forward voltage must still remain with

The wattage rating describes the maximum output power of a driver or power supply, but it does not automatically prove suitability for an LED load. Selection must also consider current, voltage, output window, minimum load, temperature range and dimming method. A moderate power

Project management needs clear driver information so that design, purchasing, installation, commissioning and service work from the same basis. This includes manufacturer, series, output type, current,

Architectural lighting often requires invisible integration, smooth dimming, low noise and suitable interfaces. Depending on the project, DALI, Casambi, DMX, tunable white or RGBW may be used. The driver must no

Hospitality projects place high demands on calm, warm and comfortable light. Drivers should dim smoothly, avoid disturbing noise, hold low dim levels stably and recall scenes reliably. Dim to warm, DALI, Casambi or phase cut can be sui

Museum lighting requires stable, precise and gentle light control. Drivers must hold low dim levels cleanly, minimize temporal artefacts and work with changing exhibition scenes. Conservation

An LED driver is the control gear between the mains supply and the LED load. It provides the required current or voltage and, depending on the device, protects the LED against short circuit, overload or overtemperature. In professional luminaires, the driver affects not only basic operation but also dimming quality, flicker, lifetime and serviceability. It should therefore be sele

DALI bus current supplies communication and certain DALI components on the bus line. If too much current is consumed or several components supply bus voltage without coordination, communication faults can occur. Wit

Derating means that a driver may not be operated at full rated power under certain conditions. Typical triggers are high ambient temperature, poor heat dissipation, tight installation spaces or unfavourable mounting positions. The decisive value is n

Flicker describes time based fluctuations in light output. These variations may be visible, only indirectly perceived by people or noticed only in camera footage. Causes often lie in the interaction between driver, dimming method, mains quality, PWM frequency, LED load and control system. A proper assessment

Long LED output cables can cause voltage drop, EMC issues, losses, uneven brightness or unstable dimming behaviour. In constant voltage systems, voltage drop increases significantly with current and length. In constant

0?10 V and 1?10 V differ mainly in the lower signal range and off behaviour. In some systems, a low control value means only minimum light level, not mains off. There are also differences between current sink and current source, which may be described differently in international produ

A constant current driver regulates a fixed output current and adjusts its output voltage within a defined range to suit the LED load. A constant voltage power supply, by c

Analogue dimming changes the LED current continuously. PWM dimming switches the LED rapidly on and off and controls brightness through the duty cycle. Both methods can work in professional installations, but they differ in

DALI is the established digital lighting control protocol, while DALI 2 extends testing and certification logic and improves interoperability between control gear, sensors, input devices and control components. In practice, this doe

The driver electrically supplies the LED load. A controller generates control commands, for example for DALI, 0?10 V, PWM, DMX or Casambi. A gateway translates between system worlds, such as from building automation to DALI

DT6 and DT8 describe different device types within DALI. DT6 is typically used for a single LED channel. DT8 can combine colour or colour temperature functions in one DALI device, such as tunable white or RGBW. In tunable white projects, DT8 can reduce addressing effort if the controller and driver

Electrical compatibility means that current, voltage, power, protection rating and load type

Tunable white usually mixes warm white and cool white LED channels to change colour temperature. The driver must control the channels separately, stably and repeatably. Depending on the system, control may be via DALI DT8, multiple DT6 addresses, Casambi, DMX or a ma

Before first power up, mains voltage, protection class, LED polarity, load type, output current, voltage window and dimming connection must be checked. With programmable drivers, the configured current and dimming parameters

With phase cut drivers, the combination of dimmer, driver and LED load must be checked. Minimum load, load range, leading edge or trailing edge method, dimming range and acoustic behaviour are decisive. Many problems appear only at low dim lev

Surge protection is especially important in outdoor, street, industrial and large building lighting. Lightning events, switching operations or mains disturbances can damage drivers or cause premature ageing.

NFC programming makes driver configuration fast and repeatable, especially in series production or installations with many identical luminaires. It does not replace electrical verification of LED load, current value, voltage window and di

PWM controllers must match the supply voltage, channel current, total power and LED load. PWM frequency, cable length, conductor cross section and feed in also influence light quality. With long 24V strips, many problems are not caused by the power

Purchasing should check not only price and delivery time but also output type, current, voltage window, power, dimming method, protection class, temperature range, approvals, configurability and replacement availability.

Industry and warehouses need reliable drivers for long operating hours, high mounting heights, temperature stress and often sensor based control. Efficiency, lifetime, inrush current, EMC, service access a

In 48V track systems, supply, adapters, luminaire electronics and control are closely connected. The driver may be located centrally in the power supply, locally in the luminaire adapter or inside the luminaire, depending on the s

Pst LM and SVM are metrics for temporal light artefacts. Pst LM describes short term flicker perception, while SVM evaluates stroboscopic effects during motion. Both values are more meaningful for professional lighting than simple percent flicker figures because the

Form factor determines whether a driver fits a luminaire or installation mechanically, thermally and from a service perspective. Length, width, height, mounting method, terminal access, strain relief, housing material and tc point position are relevant. A driver that is electrically suitable may still be unsuitable i

IP66 or IP67 is required when drivers must be protected against dust, moisture, water spray or temporary wet conditions. Typical applications include outdoor lighting, façades, industry, damp rooms and certain floor level or roof areas. T

0?10 V is sufficient when simple analogue group dimming is needed without individual addressing, feedback or complex scenes. It is robust and easy to understand but offers less system data and flexibility than DALI. For simple zones, individual rooms or cost sensi

A programmable driver is useful when different LED modules, light outputs or project requirements should be covered with fewer device variants. Depending on the series, output current, dimming curve, minimum

Casambi is useful when flexible groups, scenes and app operation are desired or when additional control wiring would be difficult to retrofit. It is especially suitable for existing buildings, retail areas, hospitality and small to medium

Constant current is used when the LED load requires a defined operating current, for example COBs, LED engines or many professional luminaire modules. Constant voltage suits systems designed for a fixed supply voltage, such as 24V LED strips or certai

DMX is used when many channels, fast changes, precise colour sequences or show like scenes are required. Typical applications include media façades, stages, entertainment, dynamic architectural lighting and effect lighting. DALI is more

DALI is flexible in topology but not unlimited. Cable length, cross section, bus current, voltage drop and terminal quality influence reliable communication. It becomes critical especially with distant devices, large installations, thin cables or poor t

DALI compatible drivers include a DALI interface and support defined functions within the IEC 62386 environment. However, DALI, DALI 2, DT6, DT8 and D4i should not be treated as interchangeable, each profile brings its own requirements for addressing, functions and data. eldoLED and Li

High quality retail lighting requires drivers with precise dimming, low temporal light modulation, reliable scene control and good colour stability. Accent light, light lines and decorative elements are often controlled d

Office lighting requires efficient, durable and controllable drivers for panels, linear systems, downlights and sensor integration. DALI or DALI 2 is often useful when daylight control, presence detecti

Outdoor and street lighting requires drivers that are robust against temperature, moisture, surge events and long operating hours. IP protection, surge immunity, efficiency and maintenance access are key criteria. In conne

RGBW requires four separately controllable channels and therefore an interface that supports the channel count, dynamics and user logic. DMX suits fast colour changes, shows, façades or many channels. DALI DT8 can be useful for building relate

Typical protection functions include short circuit, overload, open circuit, surge and overtemperature protection. How these functions react is model dependent: some drivers restart automatically, others require a m

When integrating drivers into luminaires, the driver must fit the design electrically, thermally and mechanically. This includes insulation distances, strain relief, terminal access, pr

Relevant standards for LED drivers include safety, performance, EMC and communication standards. IEC 61347 2 13 concerns safety requirements for LED control gear, IEC 62384 covers operating performance, and IEC 62386 relates to the D

Power factor and harmonics affect mains loading, especially when many drivers operate at the same time. A single small driver may appear uncritical, but large installations with many devices can influence power quality, protection

Communication problems on a DALI line are often caused by missing or low bus voltage, voltage drop, short circuit, poor terminals, old addresses or uncoordinated bus supplies. Diagnosis should com

At low dimming levels, the driver operates close to its regulation limit. Small deviations in load, minimum current, PWM resolution or dimming curve become much more visible than at full output. Unsuitable dimmers or mismatched control profiles can

Faint afterglow after switch off can be caused by leakage currents, capacitive coupling, electronic switches, long parallel cables or driver standby behaviour. 0?10 V or DALI systems may also appear optically off while the electronics rem

Different dimming behaviour within one group can result from different driver models, dimming curves, minimum dim levels, LED modules or non identical configuration. Replacement devices can also react visibly

Many 0?10 V systems do not switch fully off because the interface only defines the light level while mains power remains present. Depending on the driver, 0 V may mean minimum light, standby or dim to off, true off may require an additional relay. Wrong polarity, incorr

A DALI driver can appear offline in Casambi if bus voltage is missing, the DALI line is interrupted, the wrong profile has been selected or bus power is unclear. Too many devices or an unsupported device type can also cause problems. The app

If a DALI driver does not respond, possible causes include missing bus voltage, wrong address, bus short circuit, excessive bus load, old group assignment or an unsupported device type. If the driver responds to broadcast but not to short address, an addressing problem is l

If a driver fails after some time and works again after cooling, thermal protection is a likely cause. Common reasons include excessive load, incorrect current programming, poor heat dissipation, installation inside insulati

If an LED driver fails to start, the cause is often a load outside the output window, wrong polarity, short circuit, open load or active protection mode. With programmable drivers, an incorrectly set output current can also be involved. In DALI or 0?10 V installations, it should additi

An LED driver gets too hot when load, ambient temperature, installation space or heat dissipation do not match the design. Common causes include overload, excessively programmed current, installation inside insulation, lack of air circulation or nearby heat sources. The key check is the tc val

Buzzing often comes from magnetic components, resonance, phase cut operation, unsuitable dimmers or operation outside the recommended load range. Acoustic effects can become more noticeable at low dim levels. In hotels, museums, restaurants or quiet office zones, noise behaviour i

A colour temperature change during dimming may be intentional, as in dim to warm, or may indicate a problem. Causes include channel imbalance, incorrect tunable white configuration, voltage drop in CV systems, temperature drift or differen

Cameras can reveal temporal light modulation that the human eye barely notices. PWM, mains ripple, low dim levels and rolling shutter sensors in particular can create banding or brightness pumping in images. The result also depends on shutter speed, frame rate and camera settings.

When replacing a driver, more parameters must match than form factor and wattage. Output type, current, voltage window, dimming method, dimming curve, minimum dim level, interface and any programming are decisive. A replacement device may w

Flicker can be caused by driver selection, an unsuitable LED load, dimmer incompatibility, mains ripple, PWM frequency, voltage drop or temperature. Diagnosis should proceed step by step: first check load type and driver output, then dimming method,