The following introduces three different connection methods and the form of the suitable driving circuit.

1. LED series connection

The biggest advantage of using this connection method is to ensure that the current on each LED lamp is the same, so that the brightness of each lamp can be kept highly consistent, but when the number of lamps is relatively large, this connection method will require a high output from the driver. voltage.

For the series connection mode, if a constant voltage drive is used, when a certain LED lamp is short-circuited, the voltage on other LED lamps will increase, resulting in a large current change, and a large change in brightness, even Excessive current will burn out the LED light. If a constant current driving method is adopted, this defect will be overcome. Of course, regardless of the constant voltage or constant current driving mode, once a certain LED light is open-circuited, the entire LED light string cannot work normally.

2. Parallel connection of LEDs

When the output voltage of the driver is relatively low, it is suitable for parallel connection, but at the same time, this method requires the driver to be able to provide a relatively large driving current. The advantage of this driving method is that when one of the LEDs is opened, it will not affect other normal operation of the LEDs.

The biggest disadvantage of this connection method is that the current consistency between each channel is very poor, resulting in the inconsistency of the brightness of each LED, which is caused by the mismatch of the forward voltage drop of each LED lamp. This connection method should choose LED lights with high consistency.

In addition, this connection method is suitable for constant voltage drive, but not for constant current drive, because if the constant current drive method is used, when one of the paths is open, the excess current will flow through other LEDs, causing other LEDs. Changes in LED brightness can even cause LED lights to burn out due to excessive current.

3. Hybrid (series-parallel) mode

The above two connection methods are only suitable for the case where there are few LED lights, but many electronic products today, such as large-size monitors, LCD TVs, etc., require a lot of LED lights for backlighting. If you simply use series or parallel at this time. The connection method requires a high output voltage or a large driving current of the drive circuit, which will undoubtedly increase the design difficulty and design cost.

In this case, considering the respective characteristics of the two connection methods, a hybrid connection method can be adopted, that is, a constant current drive is performed for each channel, and the total current output terminal above adopts a constant voltage structure. This connection method can Overcome the disadvantages of ordinary mixed connection.