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An LED Driver General Requirements

By: DeRun   Views:6322  

The arrangement of the LED and the LED light source specification determines the basic drive requirements. The main function of the LED driver is in the range of operating conditions restrict flow through the LED current, regardless of the input and output voltage changes. The most common is the use of transformers for electrical isolation. This paper discusses the factors to consider LED lighting design.

An LED driver General requirements

Drive LED faces a number of challenges, such as the forward voltage changes with the change of temperature, current, there will be differences in the different individuals, different batches of different suppliers of LED forward voltage; addition, LED’s color “will drift with the current, and temperature changes.

In addition, the application typically uses multiple LEDs, which relates to the problem of multiple LED arrangement. A variety of arrangement, the preferred single-string LED driver series, because in this way, regardless of forward voltage changes, the output voltage (Vout) how to “drift”, provides excellent current matching performance.

Of course, users can also parallel and series – parallel combination and cross-connect other arrangement for the LED forward voltage applications need to match each other, and get other benefits. In the cross-connect, if one LED open circuit due to a fault, only one LED drive current in the circuit will double, so as to minimize the impact on the entire circuit.

It is worth mentioning that the AC-DC power converter with constant current driver, LED lighting design, these two parts of the circuit can be used in different configurations:

1) Integral (Integral) configuration, that is, the two together, are located within the lighting, the advantage of this configuration include optimizing energy efficiency and simplify installation;

2) distributed (distributed) configuration, that is, they stand alone, this configuration to simplify security reasons, and increase flexibility.

LED driver depending on the application requirements, constant voltage (CV) output, output voltage clamp certain current range; constant current (CC) output can also be used, the design of the output strictly limited current; may adopt constant current constant voltage (CCCV) output, which provides a constant output power, as the forward voltage of the LED load to determine its current.

Overall, LED lighting design needs to consider the following factors:

Output Power: LED forward voltage range, current and LED arrangement involved.

Power Supply: AC-DC power supply, DC-DC power supplies, AC power drive .

Functional requirements: the requirements of the dimming, dimming mode (analog, digital, or multi-stage), lighting control.

Other requirements: energy efficiency, power factor, size, cost, fault handling (protection features), to follow the standard and reliability .

More considerations: mechanical connection, installation, repair / replacement, life cycle, logistics .