VISUAL SOLUTIONS

LED Driver Improves Performance of LED Lighting at Low Cost

The use of LEDs in illumination has expanded dramatically over the last few years. As LED performance has improved and price declined, the cost of the LED driver electronics has become an important consideration for system designers. The BCR4xxx series of linear LED drivers are low cost alternatives to the resistor biasing approach commonly used.



One common and inexpensive way of supplying current to LEDs is via a simple resistor circuit. While this may initially appear to represent the lowest cost solution, the penalty may be performance issues such as colour and intensity variation and thermal degradation.

Some of these effects can be reduced by matching resistors to LED bins and specifying more expensive, more tightly controlled supplies. However, such solutions inevitably increase the overall solution cost.

The BCR40x series of low cost, linear LED drivers from Infineon Technologies provides a low cost alternative for such applications. The devices eliminate the production and supply complexity associated with resistor matching, reduce power supply limitations and provide protection against thermal degradation.

The drivers are extremely small (down to 2mm x 2mm) with few external interconnections. They include an adjustable constant-current output, PWM input and thermal compensation that reduces the current variation with temperature.

A second common biasing technique uses a switch mode current source. These offer high efficiency and high current drive capability but are relatively costly; they also present ElectroMagnetic Interference (EMI) radiation concerns and are complex, since they require many external components. The electrolytic capacitor, one of the externally required components in such a solution, can reduce the lifetime of the LED system far below the 50,000h lifetime of the LED as the capacitor dries out over time.

Infineon’s BCR450 driver, when combined with an external transistor, provides a constant-current alternative to the switch mode solution for high power LEDs at 40% to 50% lower cost. The entire system requires just five components, occupies little board space and presents no EMI problems.

Features

• Linear-mode LED driver
• 0mA to 85mA drive capability
• Cost-effective solution
• 27V maximum operating voltage, 40V maximum rating
• High-precision current control: ±1.5% at +25°C
• Overcurrent and overvoltage protection
• Thermal shutdown protection for LEDs
• Logic-level enable input
• Direct PWM dimmable
• Compact SC74 package

Applications

• Channel letters
• Architectural and landscape lighting
• Interior and exterior building illumination
• EMI-sensitive lighting applications, such as medical lighting
• Aircraft and public transportation lighting
• General purpose lighting

For more information about Infineon LED Drivers, including the BCR4xx LED Driver Sample Kit Brochure, please click here