Intelligent LED Driver Solutions

Featured LED Solution

Digital LED Lighting Development Kit with DMX512 Standard

Generating PWM Control Signals

Charge Pump Driver
Smart Buck Driver
Boost Driver
High Efficiency 12V Boost Controllers
Smart Buck Boost Driver
High Speed PWM Controllers
SEPIC Driver

Digital vs. Analog Control
Low Cost Digital Control
High Performance Digital Control
Offline Flyback Converter Design

The Digital LED Lighting Development kit which incorporates DMX512 Standard allows developers to create a 100% digitally controlled ballast function, while including advanced features such as dimming and color hue control.

LED Partners

LEDs are no longer used just for providing the pretty red and green indicator lights on electronic equipment. Advances in the technology have allowed LEDs to be used as practical sources of illumination.

The primary benefits of LEDs are:

Long life, when driven properly, a power LED can last tens of thousands of hours with minimal degradation of the light output.

Durability, since the LED is a solid-state device, it can withstand shock and vibration that would damage most other light sources.

Energy efficiency, the typical efficacy of a power LED, is currently (2008) in the range of 60 to 100 lumens per watt [lm/W]. This is several times greater than that of incandescent light sources and is only exceeded by high-intensity discharge lamps (HID) and some fluorescent light sources.

Cree Inc.

(courtesy of CREE Inc)

LED Applications

The benefits of LED lighting can be appreciated in many types of lighting applications:

Efficient LED Control

LEDs must be driven with a source of constant current. Most LEDs have a specified current level that will achieve the maximum brightness for that LED without premature failures. LEDs could be driven with a linear voltage regulator configured as a constant current source. However, this approach is not practical for higher power LEDs due to power dissipation in the regulator circuit.

A switch-mode power supply (SMPS) provides a much more efficient solution to drive the LED. An LED will have a forward voltage drop across its terminals for a given current drive level. The input supply voltage and the LED forward voltage characteristics determine the SMPS topology that is required.

Multiple LEDs can be connected in series to increase the forward voltage drop at the chosen drive current level. The SMPS circuit topologies adopted to regulate current in LED lighting applications are the same used to control voltage in a power supply application. Each type of SMPS topology has its advantages and disadvantages as presented in the table below.

Fundamental SMPS Topologies

Topology

Vin – Vout
Relationship

Complexity

Component Count

Comments

Charge Pump

Vout < Vin < Vout

Low

Medium

Limited Iout range
No inductors

Buck

Vin > Vout

Medium

Medium

Chopped Iin
High side drive

Boost

Vin < Vout

Medium

Medium

Extra parts needed to isolate output from input

SEPIC

Vout < Vin < Vout

Medium

High

Smooth Iin
Multiple Outputs
Two Inductors

Buck-Boost

Vout < Vin < Vout

High

High

Single Inductor
Up to four switches

Flyback

Depends on transformer design

Low

Low

Provides isolation
Less efficient