LED Dimming & Driver Guide

A Practical Explanation for Designers, Consultants & Clients

Modern lighting is not just about choosing the fixture the driver and dimming method define performance, comfort, and reliability.

This guide explains LED drivers and dimming types in a simple, practical way.

1. What Is an LED Driver?

An LED driver converts mains power (220–240V AC) into a controlled output suitable for LEDs.

It also controls brightness, stability, flicker, and lifespan.

There are two main types of LED drivers:

• Constant Current (CC)
  
• Constant Voltage (CV)
  

Choosing the wrong type can lead to flicker, poor dimming, or LED failure.

2. Constant Current (CC) Drivers

What Is a Constant Current Driver?

A CC driver supplies a fixed current while automatically adjusting voltage based on the LED load.

Typical Applications

• COB downlights
  
• Spotlights & track lights
  
• Wall washers
  
• High-power linear architectural lights
  
• Façade & outdoor luminaires
  

Key Specifications (CC Drivers)

• Output Current:Common values: 350mA, 500mA, 700mA, 900mA, 1050mA
  

• Output Voltage Range: Example: 25–42V DC
  

• Power Rating: Example: 30W, 40W, 60W
  

• Dimming Support: DALI / 0–10V / Phase dimming / PWM (model dependent)
  

• Protection: Short-circuit, overload, thermal protection
  

Advantages

• Precise light output
  
• Excellent dimming stability
  
• Longer LED lifespan
  
• Ideal for professional & architectural lighting
  

Important:
The driver current must match the LED exactly. Over-current will damage the LED.

3. Constant Voltage (CV) Drivers

What Is a Constant Voltage Driver?

A CV driver delivers a fixed voltage (typically 12V or 24V), and the LED load controls the current.

Typical Applications

• LED strip lights
  
• Cove lighting
  
• Flexible linear lighting
  
• RGB / RGBW tape lighting
  

Key Specifications (CV Drivers)

• Output Voltage: 12V DC or 24V DC
  

• Maximum Power: Example: 100W, 200W, 300W
  

• Connection Type: Parallel wiring
  

• Dimming Support: 0–10V / DALI / PWM / Phase dimming
  

• IP Rating: IP20 (indoor), IP65 / IP67 (outdoor)
  

Advantages

• Simple installation
  
• Flexible layout
  
• Ideal for decorative lighting
  

Important:
Never mix 12V LEDs with 24V drivers (or vice versa).

4. LED Dimming Methods Explained

Phase Dimming (TRIAC)

Leading Edge (Forward Phase)

• Cuts the front part of the AC waveform
  
• Older technology
  

Pros

• Widely available
  
• Low cost
  

Cons

• Flicker at low levels
  
• Audible buzzing
  
• Limited LED compatibility
  

Trailing Edge (Reverse Phase)

• Cuts the end part of the AC waveform
  
• Designed for LEDs
  

Pros

• Smooth dimming
  
• Quiet operation
  
• Better low-level control
  

Cons

• Requires compatible driver
  
• Slightly higher cost
  

0–10V Dimming

A separate low-voltage control signal controls brightness.

• 10V = 100% brightness
  
• 0V = minimum level or OFF
  

Key Points

• Requires two additional control wires
  
• Analog control system
  

Pros

• Flicker-free
  
• Reliable and stable
  
• Common in commercial projects
  

Cons

• No individual addressing
  
• Limited automation features
  

DALI (Digital Addressable Lighting Interface)

A digital lighting control system designed for professional projects.

Key Features

• Each driver has a unique address
  
• Grouping, scenes, scheduling
  
• Two-wire, polarity-free control bus
  
• Feedback & monitoring
  

Pros

• Highly flexible
  
• Ideal for offices, hotels, malls, villas
  
• Scalable and future-proof
  

Cons

• Higher initial cost
  
• Requires programming & commissioning
  

PWM (Pulse Width Modulation)

Controls brightness by rapidly switching LEDs ON and OFF.

Commonly Used In

• CV LED strips
  
• RGB / RGBW controllers
  
• DMX lighting systems
  

Pros

• Excellent low-level dimming
  
• No color shift
  

Cons

• Poor-quality PWM can cause flicker
  
• Frequency must be properly designed
  

5. CC vs CV – Quick Comparison