LED Power Supplies for Streetlight Applications

For LED street lighting, the power supply is the most critical factor of the complete light. LED power supplies for street lighting must have special design and technical features and use high quality components to ensure the lifetime of the power supply matches that of the streetlight, more than 20 years.

RECOM Lighting LED drivers are used by many global street lighting manufacturers, and the installed base is growing day by day! Alongside the traditional IP67 sealed power supplies on the market today, RECOM Lighting undertook a very interesting solution for a major street lighting manufacturer by designing a new generation of product, using a two-stage topology. 

The advantage of this topology is, that the AC/DC power supply with the temperature critical electrolytic capacitor (this is one of the lifetime limiting factors) is housed in the pole of the streetlight, the natural airflow helps to extend the lifetime by cooling the AC/DC power supply. This pole mounted power supply then drives a low voltage LED driver in the lamp head. This power supply will not increase the temperature of the lamp head (i.e. at 90W and an efficiency of 90% about 9W will be converted into heat) which has advantages for the form factor and lifetime of the lamp head.

As the AC/DC power supply is most critical maintenance is easy as it is located at ground level, therefore no roads need closing for overhead working.

The LED segments with the drivers are located in the lamp head. The DC/DC (RCD-48) driver, which is built only in using ceramic capacitors, is able to operate up to temperatures of 85°C, the maximum power is 70 watt. It has an efficiency of >96% - less energy is converted into heat, offering excellent in-service life. The LED-lamp modules can be used at full power or as an option controlled by a microcontroller using the PWM input to the RCD-48 driver, which enables dimming or remote switching.

Another advantage of this application is scalability, the streetlight itself is configurable for location and purpose, using different modules and optics for different light output and light distribution curves.