--- title: "PWM Dimming (CV)" description: "Constant-voltage PWM dimming of 12/24 V LED strips, RGB and tunable white lights on LED/OC modules: PWM frequency up to 25 kHz, dimming curves, mixing." url: "https://taphome.com/en/docs/functional-areas/lighting/dimming-cv/" language: en lastmod: 2026-10-08 generator: hugo ai: topics: ["pwm-dimming","led-dimming","rgb-lighting","tunable-white","constant-voltage","dimming-curves"] questions: ["What is the recommended PWM frequency for LED strip dimming?","How do I configure tunable white (dual white) lighting in TapHome?","What is the difference between Balanced and Max mixing type for dual white lights?","What does the Relative luminance (CIE 1931) setting do for LED dimmers?","Why are PWM frequencies below 400 Hz not recommended for LED dimming?","How do I set the PWM frequency on an LED/OC module?","What is the default dimmer step time value?","How do I wire and set up an RGBW LED strip through a LED/OC (LEDOC) module in TapHome?","Can I use a common (shared) ground for two different lights on a 12 LED OC module?","How do I connect a CCT panel on a 12 LED OC module to mix warm and cool white?","Can I control a 12V RGB LED strip with a 6UI/6OC or UO6 device?","What is the difference between a LED Dimmer and a PWM output on the LED/OC module?"] --- # PWM Dimming (CV) Control of LED, RGB and dual white lighting using PWM dimming with constant voltage. Supports professional frequencies and advanced color settings. Last updated: 2026-10-08 PWM (Pulse Width Modulation) dimming with constant voltage is used to control LED strips, RGB lights and tunable white fixtures connected to a 12 V or 24 V power supply. ## PWM frequency setting LED dimming modules (LED/OC) support professional frequencies up to **25,000 Hz**. In practice, due to cabling properties and the fixtures themselves, a suitable frequency may need to be found: - **Values below 400 Hz** can be disruptive (stroboscopic effect) - **At some frequencies** audible whining may occur - **At very high frequencies** the signal may blend between cycles and dimming will not be linear - **Recommended value:** a safe value is, for example, 587 Hz > [!NOTE] > Individual modules share PWM frequencies across multiple channels. For example, a 12-channel LED/OC module has two output groups, each with its own adjustable frequency. ## Output types on the module LED dimming modules (LED/OC) have outputs configurable as: ### **Universal outputs** One output = one device: - **Digital output** - on/off without dimming - **LED Dimmer** - adjustable frequency 1 - 25,000 Hz, suitable for constant-voltage dimming of LED strips - **Pulse-width modulation** - slow PWM with a period of 0.5 s - 7,200 s, used for example for gradual opening of 24 V thermostatic valves ### **RGB / RGBW Lights** Multichannel devices using 3–4 outputs: - **RGB** - 3 outputs (Red, Green, Blue) - **RGBW** - 4 outputs (Red, Green, Blue, White) Each output is assigned to one channel of the module. ### **Tunable white light** Uses 2 outputs to mix color temperature: - **Output 1** - one of the module's channels (usually warm white) - **Output 2** - one of the module's channels (usually cool white) ### **Blinds, roller shutters, mix valves** > [!NOTE] > On LED modules, this functionality is rarely used and is included only for completeness. They use 2 outputs for 1 device: - One output for opening (**Up**) - The second output for closing (**Down**) Both outputs must be on the same module, at any positions within the module. ## **Service settings** devices ### **LED Dimmer** values - **Min value** - default: 0 % - **Max value** - default: 100 % - **Use other value when output is turned off** - default: off - **Negate output** - default: off - **E.g. value 80% sets physical device to 20%.** #### Dimming curves - **Relative luminance** - default: enabled - **Based on CIE 1931 standard. Increase of light power leads to smaller increase of perceived luminance. If this setting is turned on, change of brightness e.g. between 50% - 100% will be more visible.** - **AC dimming** - default: off - The set brightness level is considered as a flat area under the sine curve - Power linearization, most noticeable for values close to 0% and 100% > [!WARNING] > This setting makes sense mainly for 230 V dimmable bulbs. For constant-voltage PWM dimming of LED strips it does not make sense. #### Additional settings - **Dimmer step time** - 0 - 2,000 ms (default: 200 ms) - Defines how the module should gradually change output values to make transitions smooth - For longer dimming actions (defined in actions) the controller will divide the dimming into shorter segments - Gradual dimming reduces inrush currents #### PWM - **PWM frequencies for the output group** - 1 - 25,000 Hz ### **Tunable white light** The module blends the color temperature within the range defined by outputs 1 and 2. #### Output 1 - **Output** - one of the module's channels - **Color temperature** - K (Kelvin, e.g. 2700 K for warm white) - **Intensity** - lm (lumens) #### Output 2 - **Output** - one of the module's channels - **Color temperature** - K (Kelvin, e.g. 6500 K for cool white) - **Intensity** - lm (lumens) #### Mixing type - **Balanced** - **The total light output does not change depending on the color temperature. For example: at 100% power and average color temperature, both channels (warm and cold) are running at 50% light output.** - **Max** - **For each color temperature, the system calculates the maximum possible output for each channel. For example, at 100% power and average color temperature, both the warm and cool channels go to 100% power.** #### Values - **Min value** - default: 0 % - **Max value** - default: 100 % - **Use other value when output is turned off** - default: off (0) ### **RGB / RGBW Lights** #### **Output Red** - **Output** - module channel - **Intensity** - lm (lumens) #### **Output Green** - **Output** - module channel - **Intensity** - lm (lumens) #### **Output Blue** - **Output** - module channel - **Intensity** - lm (lumens) #### **Output White** > [!NOTE] > Displayed only for the RGBW version. - **Output** - module channel - **Intensity** - lm (lumens) - **Color temperature** - K (Kelvin) #### Mixing type **This setting makes sense only if the individual color components have a different intensity in lumens.** Colors have different intensities in lumens. - **Min** - **Prioritizes color accuracy. Channels with higher light output may not be used at 100%** - **Max** (default) - **Prioritizes maximum performance, at the expense of color accuracy. This setting is practical when the power of the white channel of RGBW light is significantly higher than the power of the R, G and B channels.** #### Values - **Min value** - default: 0 % - **Max value** - default: 100 % - **Use other value when output is turned off** - default: off (0) **See also** — [Dimming 0 / 1V - 10V](https://taphome.com/en/docs/functional-areas/lighting/dimming-0-10v/), [Light Controller](https://taphome.com/en/docs/smart-rules/lighting-controller/).