Casambi CBU-PWM4 – 4-Channel Bluetooth PWM Dimmer (Discontinued)

LED strips and constant voltage LED modules are the most common load type in architectural and decorative commercial lighting. But integrating them into a Casambi wireless control system requires a different approach from 0-10V or DALI modules. CBU-PWM4 was Casambi's answer: a 4-channel Bluetooth PWM dimmer installed directly between a 12-24 VDC power supply and the LED load, supporting RGBW and Tunable White in a single compact module.

Note: CBU-PWM4 has been discontinued (End of Sale 31 January 2025) and is replaced by CBU-PWM4-LR with Bluetooth Long Range and richer functionality. This page is maintained for reference to support existing installations.

What Is the CBU-PWM4? A 4-Channel Bluetooth PWM Dimmer

CBU-PWM4 is part of the CBU (Casambi Bluetooth Unit) product line, designed to control constant voltage LED loads using PWM (Pulse Width Modulation). It installs between a 12-24 VDC LED power supply and the LED load, receives wireless commands from the Casambi mesh network, and adjusts the PWM duty cycle to dim each channel independently.

The key distinction from CBU-ASD or CBU-A2D is the load type: CBU-PWM4 is designed for constant voltage loads such as LED strips and modules, not for LED drivers with 0-10V or DALI interfaces. Selecting the wrong module type for the load will result in incorrect operation or no dimming at all.

4-Channel Architecture and 6A Current Distribution

CBU-PWM4 provides 4 independent PWM output channels, but the total output current is shared: 6A (EU) or 4A (US/Canada). This total can be freely distributed across channels to match the actual load balance of the installation.

Practical examples:

• RGBW (4 channels): 1.5A per channel (total 6A). Suitable when all four color channels carry roughly equal loads.

• Tunable White (2 channels): 3A to warm white, 3A to cool white, or asymmetric depending on the strip wattage per channel.

• Single high-power channel: All 6A directed to one channel when driving a high-wattage single-color LED strip run.

• Mixed: Any combination, provided the total does not exceed 6A (EU). Exceeding this limit triggers the overcurrent protection.

Maximum output power is 144W at 24 VDC (EU), or 72W at 12 VDC. Running a 24V supply maximizes available power and reduces resistive losses over longer strip runs.

Applications: RGBW, Tunable White, and Constant Voltage LED Strips

CBU-PWM4 is well suited for the following lighting control architectures:

• RGBW: Four channels for Red, Green, Blue, and White. Enables full color control plus dedicated white mixing for better color rendering than RGB alone.

• Tunable White: Two channels for warm and cool white mixing. Practical for offices, hotel rooms, and meeting spaces requiring color temperature variation throughout the day.

• Single or dual channel dimming: Single-color LED strip, or two independently controlled zones from one module.

• Architectural lighting: LED strips in ceiling coves, stairwells, display cases, and signage where a small form factor and wireless control are required.

Load selection note: CBU-PWM4 is compatible with constant voltage loads only (12V or 24V DC). Do not connect constant current LED strips directly without an appropriate constant current driver in between.

Circuit Protection: Overvoltage, Overcurrent, and Short Circuit

CBU-PWM4 includes three hardware protection layers:

• Overvoltage: Disconnects the circuit when input voltage exceeds safe limits, protecting both the module and the LED load.

• Overcurrent: Limits total current when the combined load exceeds 6A (EU), preventing overload of the power supply and output wiring.

• Short circuit: Immediately trips on any output channel short, with automatic recovery once the fault is cleared.

These three layers reduce failure risk in real installations, particularly when LED strips have exposed solder joints, are cut incorrectly, or moisture ingress occurs.

Installation: Wiring Between the 12-24 VDC Supply and LED Load

Basic wiring topology:

• AC mains → LED Power Supply (12 or 24 VDC) → CBU-PWM4 input → CBU-PWM4 output (per channel) → LED strip or module.

• CBU-PWM4 has no direct AC input. A separate DC LED power supply is always required upstream.

• Size the power supply at least 20% above the total connected load to avoid continuous full-load operation.

• Wire each output channel with conductor cross-section matched to the actual current on that channel. Do not share a single conductor pair across multiple channels.

• Commission the device into the Casambi BLE Mesh network via the app after powering up.

Discontinued Status and Replacement Products

CBU-PWM4 has reached end of life:

• End of Sale: 31 January 2025 — no longer available to order.

• Last Customer Ship: 31 May 2025 — final delivery date.

The official replacement products are CBU-PWM4-LR and CBU-PWM4-4-LR, which introduce Bluetooth Long Range (+8 dBm), richer control features, and better performance in metal housing luminaires or deep-recessed installations.

Existing installations running CBU-PWM4 continue to operate normally and remain fully compatible with the current Casambi app. Replacement is not required if the system is functioning correctly.

Conclusion

CBU-PWM4 was a capable 4-channel Bluetooth PWM dimmer for constant voltage LED strip applications in RGBW, Tunable White, and architectural lighting projects. It has been discontinued and replaced by CBU-PWM4-LR for new installations.

Contact KNXStore for advice on current LED strip dimming solutions with Casambi: hotline 0918.918.755 or email sales@knxstore.vn.