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Four connection methods for LED drive


Nowadays, many LED products use constant current drive to drive LEDs, and LED connection methods are also designed according to actual circuit needs. There are generally four forms of connection: series, parallel, hybrid, and array.

    1、Series connection method

This series connection method has a relatively simple circuit, with the head and tail connected together. The current flowing through the LED during operation is consistent and good. As the LED is a current type device, it can basically ensure that the luminous intensity of each LED is consistent. The circuit using this LED connection method is simple and convenient to connect. However, 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, which will correspondingly improve reliability.

It is worth noting that if an LED constant voltage driving power supply is used to drive an LED, the circuit current will increase when a certain LED is short circuited. When a certain value is reached, the LED will be damaged, resulting in all subsequent LEDs being damaged. However, if an LED constant current driving power supply is used to drive an LED, the current will remain basically unchanged when a certain LED is short circuited, and it will not affect the subsequent LEDs. Regardless of which method of driving is used, once an LED opens, the entire circuit will not be lit.

  2、 Parallel connection method

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

It is worth noting that the parallel connection method requires a lower voltage, but due to the different forward voltage drop 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. For a certain LED that is open circuited, if constant current drive is used, the current distributed to the remaining LEDs will increase, 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 is a combination of series and parallel connections. First, several LEDs are connected in series and then connected in parallel to both ends of the LED driver power supply. Under the condition of basic consistency of LEDs, this connection method ensures that the voltage of all branches is basically equal, and the current flowing through each branch is also basically consistent.

It is worth noting that the use of hybrid connection is mainly applied in situations with a large number of LEDs, as this method ensures that LED faults in each branch only affect the normal lighting of the branch at most, which improves reliability compared to simple series or parallel connection. At present, many high-power LED lamps commonly use this method to achieve very practical results.

4、 Array mode

      The main composition of the array method is: the branch is composed of three LEDs, which are respectively connected to the Ua, Ub, and Uc output terminals of the driver. When all three LEDs in a branch are normal, all three LEDs light up simultaneously; Once one or both LEDs fail and open, it can be ensured that at least one LED is functioning properly. In this way, the reliability of each group of LED lighting can be greatly improved, and the overall reliability of the entire LED lighting can also be improved. Adopting 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.