Four connection methods for LED drivers

Nowadays, many LED products use constant current driving to drive the LED, and the LED connection methods are designed according to the actual circuit needs, generally including series, parallel, hybrid, and array forms.

1、 Series connection method

This series connection method has a relatively simple circuit, with the ends connected together. The current flowing through the LED during operation is consistent and good. As LEDs are current type devices, it can basically ensure that the luminous intensity of each LED is consistent. The circuit using this LED connection method is simple and easy to connect. But there is also a fatal drawback, which is that when one of the LEDs experiences an open circuit fault, it will cause the entire LED string to go out, affecting the reliability of use. This requires ensuring that the quality of each LED is excellent, so that the reliability is correspondingly improved.

It is worth noting that if an LED constant voltage driving power supply is used to drive the LED, when one LED short circuits, it will cause an increase in circuit current. When a certain value is reached, the LED will be damaged, resulting in the damage of all subsequent LEDs. However, if an LED constant current driving power supply is used to drive the LED, when one LED short circuits, the current remains basically unchanged and has no effect on the subsequent LEDs. Regardless of the driving method, once an LED opens, the entire circuit will not be lit up.

2、 Parallel connection method

The characteristic of parallel connection is that the LEDs are connected in parallel at the beginning and end, and the voltage borne by each LED is equal during operation. However, the current may not be equal, even for LEDs of the same model and specification batch, due to factors such as production and manufacturing processes. Therefore, uneven current distribution among each LED may lead to a decrease in the lifespan of LEDs with excessive current compared to other LEDs, which can easily burn out over time. This parallel connection method has a relatively simple circuit, but its reliability is not high, especially when there are a large number of LEDs, the possibility of failure is higher.

It is worth noting that the parallel connection method requires a lower voltage, but due to the different forward voltage drops of each LED, the brightness of each LED is different. In addition, if one LED is short circuited, the entire circuit will be short circuited, and the other LEDs will not work properly. If a certain LED is disconnected, using constant current drive will increase the current allocated to the remaining LEDs, which may cause damage to the remaining LEDs. However, using constant voltage drive will not affect the normal operation of the entire LED circuit.

3、 Hybrid mode

Hybrid connection refers to the use of a combination of series and parallel connections. First, several LEDs are connected in series, and then parallel connected together at both ends of the LED driving power supply. With the basic consistency of the LEDs, this connection method ensures that the voltage of all branches is basically equal, and the current flowing through each branch is also basically the same.

It is worth noting that the use of hybrid connection is mainly applied in situations where there are a large number of LEDs, because this method ensures that LED failures in each branch only affect the normal light emission of the branch at most, which improves reliability compared to simple series or parallel connection. Currently, many high-power LED lighting fixtures commonly use this method to achieve practical results.

4、 Array method

The main form of array configuration is: branches are composed of three LEDs as a group, which are respectively connected to the Ua, Ub, Uc output terminals of the driver. When all three LEDs in a branch are functioning properly, all three LEDs are emitting light simultaneously; Once one or two of the LEDs fail and open circuit, it can be ensured that at least one LED is functioning properly. In this way, the reliability of each group of LEDs emitting light can be greatly improved, and the overall reliability of the entire LED emitting light can also be improved. This method requires multiple sets of input power supplies in order to improve the reliability of LED operation and reduce the overall circuit failure rate.