LED Driver Noise Reduction: 3 Proven Fixes for PWM EMI

How to Reduce Noise in LED Drivers: 3 Expert Solutions

Introduction

Electromagnetic noise causes 72% of LED driver certification failures (IEEE EMC Society). This guide addresses the causes of noise in LED power supplies and delivers actionable LED driver noise reduction techniques. Learn how to eliminate audible buzzing and EMI issues while meeting EN 55015 standards.

Problem: Why LED Drivers Generate Noise

Three primary noise sources plague LED designs:

Common-mode noise (70-90% of issues):
- Caused by PWM switching currents flowing through parasitic capacitances
- Frequency range: 100kHz-10MHz
Differential-mode noise:
- Results from high di/dt loops in buck/boost converters
Magnetic coupling:
- Poor component placement induces Transformer whine

Solution 1: Optimize PCB Layout for Noise Suppression

Fix the root causes before adding components

Critical layout rules:

Keep high dv/dt traces ≤15mm long - MOSFET drains to transformer pins
Place input capacitors ≤5mm from connector
Use solid ground plane under control IC
Separate analog/digital grounds with 2mm slot

Solution 2: Select the Right Filter Components

Common-Mode Choke Selection Guide

Based on UT2024 series specifications:

Parameter	Requirement for 30W LED Driver	UT2024-222Y Performance
Inductance	1-3mH	2.2mH (min)
Rated Current	≥1.2× operating current	1.3A (50Hz)
RDC	<0.2Ω	0.165Ω
Attenuation	>40dB @ 500kHz	58dB (CM, 1MHz)

Pro tip: For high-density designs:

Use UT1609 series (9.5mm height) when space <15mm³
UT1711A series when needing >10mH inductance

Solution 3: Implement FERRTX Common Mode Chokes

Why UT2024 Series Excels for LED Drivers

Closed-core design :
- Reduces leakage inductance to <1%
- Prevents magnetic coupling to nearby components
2-section winding:
- Maintains high impedance up to 30MHz
Temperature resilience:
- Stable performance from -25°C to +125°C

Installation best practices:

Mount perpendicular to transformer (minimize coupling)
Use thermal relief pads for heatsinking
Verify creepage distance ≥3mm (critical for 250VAC designs)

Measured Results with FERRTX Components

After implementing UT2024-222Y in 50W high-bay lighting:

•500kHz noise: 52dBμV → 31dBμV
•Temperature rise: +48℃ → +29℃ • Certification: Failed → Passed EN55015 Class B

Top models for LED drivers:   • UT2024-222Y (2.2mH/1.3A) - Best for 20-50W • UT1609-681Y (0.68mH/0.85A) - Compact designs • UT1711A-232Y (2.3mH/1.7A) - High-current apps

August 09, 2025