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Design and application of LED and LED driver
Dec 08, 2016

LED has been widely used in lighting, decorative lighting products, in the design of the LED lamp, the need to consider the choice of what kind of LED driver, and LED as the series parallel load used, with reasonable design, in order to ensure the normal work of LED.

1, LED using all series

Requires LED drive output higher voltage. When the LED consistency difference is bigger, the distribution in different LED both ends voltage is different, through each LED the current is the same, the LED brightness is consistent.

When a LED of poor quality in short circuit, if the power driven (such as the commonly used resistance capacitance step-down mode) driver output voltage, the constant, the distribution would be increased in LED at both ends of the remaining drive voltage, the output current will increase, which is easy to damage the rest of the LED. Such as the use of constant current LED driver, when a short circuit of a LED quality, due to the drive output current remains unchanged, does not affect the rest of the normal work of all LED.

When a LED quality is poor, the LED in series will not be bright. The solution is in each LED parallel at both ends of a zener diode, Zener turn-on voltage of voltage higher than LED need to guide, otherwise LED is not bright.

2, LED uses all parallel way

The LED driver is required to output a large current, and the load voltage is low. Distribution in all LED at both ends of the voltage is the same, when the consistency of LED difference is bigger, and through each LED of the current is not consistent, LED brightness is also different. LED, which can pick and choose good consistency, is suitable for low power supply voltage products (such as solar or battery powered).

When a LED quality is poor, if the voltage regulator LED driver (such as voltage regulator switching power supply), the driver output current will be reduced, and do not affect the remaining all LED normal work. If the constant current LED driver is used, the output current is kept constant, the distribution of the remaining LED current will increase, resulting in easy damage to all LED. The solution is to disconnect a parallel LED, a LED, LED distribution in the rest of the current is small, does not affect the normal work of the remaining LED. So when the power type LED parallel load, it is not suitable to use constant current driver.

When a short circuit of a LED quality, then all the LED will not light, but if the number of parallel LED more, through the short circuit of the LED current is large enough to burn the LED short circuit breaker.