LED driver 4 connection methods

Nowadays, many LED products use constant current driving method to drive LEDs. Different LED connection methods are also designed according to actual circuit needs. Generally, there are four forms: series, parallel, hybrid and array.

1. Series connection method

This series connection method has a relatively simple circuit. The ends are connected together. The current flowing through the LEDs when working is very consistent. Since LEDs are current-type devices, the luminous intensity of each LED can basically be guaranteed to be consistent. The circuit using this LED connection method is simple and easy to connect. But there is also a fatal shortcoming, that is, when one of the LEDs has an open circuit fault, it will cause the entire LED light string to go out, affecting the reliability of use. This requires ensuring that the quality of each LED is excellent, so that the reliability will be improved accordingly.

It is worth noting that if an LED constant voltage drive power is used to drive the LED, then when an LED is short-circuited, the circuit current will increase. When it reaches a certain value, the LED will be damaged, causing all subsequent LEDs to be damaged. However, if an LED constant current drive power is used to drive the LED, when an LED is short-circuited, the current will remain basically unchanged and will have no impact on the subsequent LEDs. No matter which way it is driven, once an LED is open-circuited, the entire circuit will not be lit.

2. Parallel connection mode

The characteristic of the parallel connection mode is that the LEDs are connected in parallel at the beginning and the end. When working, the voltage endured by each LED is equal. However, the current is not necessarily equal, even for LEDs of the same model and specification batch. This is due to reasons such as production and manufacturing processes. Therefore, the uneven current distribution of each LED may cause the life of the LED with excessive current to be reduced compared to other LEDs, and it is easy to burn out over time. The circuit of this parallel connection method is relatively simple, but the reliability is not high, especially when the number of LEDs is large, the possibility of failure is higher.

It is worth noting that the voltage required for parallel connection is lower, but because the forward voltage drop of each LED is different, 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 broken, if a 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 connection

Hybrid connection is a mixture of series and parallel connections. First connect several LEDs in series, and then connect them in parallel to both ends of the LED driving power supply. When the LEDs are basically consistent, this connection method makes the voltages of all branches basically equal, and the current flowing through each branch is basically the same.

It is worth noting that the hybrid connection method is mainly used when the number of LEDs is large, because this method ensures that the LED failure in each branch will only affect the normal lighting of this branch at most, which improves reliability compared with simple series and parallel connections. At present, many high-power LED lamps generally adopt this method to achieve very practical effects.

4. Array mode

The main form of the array mode is: the branch is composed of 3 LEDs as a group, which are respectively connected to the Ua, Ub and Uc output terminals of the driver output. When the three LEDs in a branch are all normal, the three LEDs will light up at the same time; once one or two LEDs fail and open circuit, at least one LED can be guaranteed to work normally. 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 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.