LED driver dimming compatibility depends on the complete controller–interface–driver–LED load path. Match the electrical interface and its capacity, then verify the required minimum light level, off behavior, startup, and transitions using the exact hardware and settings. A shared label such as “0–10 V,” “PWM,” or “DALI” is a starting point. It does not define every operating limit or prove that the installed lighting system will behave as specified.
Table of Contents
Draw the actual control path before selecting a driver
For an OEM luminaire or commercial sign, identify where brightness control happens. A driver may accept a dedicated dimming signal and regulate LED current internally. Alternatively, a downstream controller may switch a constant-voltage bus to compatible modules. A phase-cut dimmer changes the AC waveform entering a driver designed for that method.
These arrangements need different evidence. A small PWM control-input rating says nothing about the current a downstream power controller can switch. A constant-voltage supply with no documented dimming interface is not automatically a phase-cut-dimmable driver.
Concept overview
Driver control input
Driver
LED load
| Control path | Document before sampling | System behavior to verify |
|---|---|---|
| Analog controller → driver dimming input → LEDs | Source/sink roles, signal range, control current, isolation, permitted wiring | Minimum level, electronic off or separate switching, endpoint consistency |
| Digital controller → driver → LEDs | Protocol, supported device functions, product identity, configuration and bus budget | Addressing, group response, fade settings, power-on and communication-loss behavior |
| Constant-voltage supply → output PWM controller → compatible modules | Supply compatibility, controller channel current, switching limits, module approval for pulsed operation | Startup, pulse behavior, acoustic noise, low-level stability |
| Phase-cut control → compatible AC-input driver → LEDs | Leading/trailing-edge support, exact controller pairing, permitted driver count and load range | Low-end stability, switch-on behavior, noise, simultaneous startup |
First confirm the load’s constant-current or constant-voltage requirement. Dimming compatibility cannot correct an incompatible power-output mode.
Check 0–10 V and 1–10 V control-current capacity
For an analog interface, determine which side supplies control current and which side sinks it. The external application note 587 explains source/sink roles, control-current limits, and why minimum level and off behavior can differ. The allowed driver count can be limited by the control circuit even when the AC switching load appears acceptable.
Consider a hypothetical source/sink system in which each driver sources up to 0.8 mA on its control pair and the selected controller can sink 20 mA per independent output. Assume 32 identical drivers and no additional devices on that control output.
- Required sink current: 32 × 0.8 mA = 25.6 mA
- Single control-output rating: 20 mA
- Result: 25.6 mA > 20 mA, so one control output is insufficient.
Two independently rated outputs with 16 drivers each would see 12.8 mA per output under these assumptions. Check that the controller permits the total connected load and grouping; keep the two outputs independent.
Check the signal voltage at the most demanding driver location using the proposed cable and full control load. Wire resistance and the controller’s low-end capability can prevent the driver from seeing the intended endpoint. Separately check AC switching current and simultaneous driver inrush; dividing control groups does not necessarily divide the mains switching event.
Write minimum level and off as separate requirements
“Dims to 1%” needs a defined quantity. It could describe commanded level, output current, or measured light output. Those are not interchangeable, and perceived brightness is another question. State the reference, measurement method, allowed variation, and whether the requirement applies to every fixture or only a sample average.
Traditional 1–10 V control can reach the driver’s minimum light level without switching the LEDs off. Some 0–10 V combinations support electronic dim-to-off; the voltage label alone does not establish that function or its threshold. The referenced relay and electronic-off guidance distinguishes minimum-output operation from explicitly supported electronic off. Check the driver and controller together, including the signal they achieve at the end of the installed cable.
When the specified control path stops at minimum output, provide a separately rated mains switch or relay for off. Check its driver count and AC startup duty as well as its continuous rating. Electronic off leaves the driver connected to AC; use the specified physical isolation procedure for maintenance.
For a hypothetical sign project, the engineering team might require a stable nighttime level of 5% of the measured full-output illuminance at a fixed test position, plus no detectable increase over the dark background above an agreed threshold when off. The team should choose those limits from the application, rather than borrow a universal acceptable percentage.
Also specify fade duration, the transition out of off, behavior after power restoration, and any required response if the control cable or communication is lost. Record the intended response before testing so a bright fallback is not accepted simply because the lamps remain on.
For DALI-2, verify device identity and digital settings
Where DALI-2 or D4i certification is a project requirement, check the DALI Alliance product database against the specific product identity. The database explains that certification is tied to the listed brand, GTIN, and hardware and firmware versions. A similar model name or a generic DALI statement is not equivalent evidence.
Then verify the functions the project actually uses: individual addressing, groups, fade behavior, control type, and configured power-on and communication-loss levels. The lighting layout also needs a documented bus-power and device-capacity budget. Include the controller, gateways, bus power supply, and relevant software versions in the tested configuration.
Component evidence reduces uncertainty, but it does not replace checking the complete LED load and installation. Changing a driver setting or replacing a gateway can change system behavior without changing the fixture’s outer appearance.
Test the intended endpoints and the transitions between them
Use the exact controller, driver suffix, LED board or module, cable length, driver count, and programmed settings. Test the smallest and largest intended groups where they differ electrically. Repeat the relevant checks at the specified input and temperature extremes and after the system reaches a stable temperature.
| Test state | Record | Acceptance basis |
|---|---|---|
| Full and minimum output | Command, signal at driver, LED current, light reading and measurement position | Project limits for output and consistency |
| Fade down and fade up | Duration, steps, dropout, delayed pickup, visible instability | Required transition and stable operating range |
| Off and restart | Residual light, flash, delay and restored setting | Defined off threshold and startup behavior |
| Communication loss and recovery | Fallback output and response after restoration | Configured project requirement |
| Relevant camera or occupied-space use | Measurement method, operating levels and observation conditions | Specified temporal-light or camera-performance criterion |
A phone-camera image can help reproduce a complaint, but camera settings can create or hide banding. Use an appropriate measurement method when a quantitative temporal-light requirement is specified. Keep visible flicker, camera banding, and audible noise as separate observations.
Request a compatibility report for the exact fixture, driver, control device, configuration and test conditions proposed for the project. Treat that report as evidence for its stated combination and conditions, rather than a guarantee for every connected system. Repeat the relevant checks when the combination or configuration changes.
Ask for the control specification with the quotation
For the XLG-100 product reference or HLG-200 product reference, identify whether brightness control is required inside the driver or through a separate controller. Ask whether the exact model and suffix supports the required control interface. Request its interface document, then compare it with the controller specification and intended LED load. These product-identity links do not confirm a dimming function or controller compatibility.
Purchasing should retain the tested bill of materials, configuration file where applicable, interface limits, and acceptance record with the production specification. The broader OEM power-supply RFQ checklist helps carry those technical requirements into comparable quotations and change control.
Contact WEHO about LED dimming compatibility. Include the LED load, controller model or proposed control method, and required minimum/off behavior. Use the sample record to confirm the complete combination before production.
Optional project record: Download the dimming-path acceptance sheet (CSV). Use it to record your own inputs and evidence; example entries are illustrative.
