What happens when a high power LED shorts in a LED series string?

In summary, the person is learning about high power LED's and wants to design a high power LED driver for a DIY project. They plan on using an LED driver to provide constant current and dimming control through PWM, using 3W high power LED's in a series configuration. They have a question about what would happen if an LED were to short and are considering using a LM3404 for the constant current driver. They also mention the importance of sensing the lower high-side voltage and reporting LED failures for product design.
  • #1
aiq25
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Hello. I'm learning about high power LED's. I would like to design a high power LED driver for a DIY project I'm working on. I'm planning on using an LED driver to provide constant current and have dimming control through PWM. I'm going to be using 3W high power LED's in a series configuration. I will have about 12 LED's in series. From what I understand the LED driver will adjust its output voltage to keep the constant current. The question I have is what would happen if an LED was to short? I'm assuming that the output voltage of the driver would be lowered to get that constant current but I'm not 100% sure, so I thought I would ask.

I think I might use a LM3404 to create the constant current driver but I'm not sure.
 
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  • #2
aiq25 said:
Hello. I'm learning about high power LED's. I would like to design a high power LED driver for a DIY project I'm working on. I'm planning on using an LED driver to provide constant current and have dimming control through PWM. I'm going to be using 3W high power LED's in a series configuration. I will have about 12 LED's in series. From what I understand the LED driver will adjust its output voltage to keep the constant current. The question I have is what would happen if an LED was to short? I'm assuming that the output voltage of the driver would be lowered to get that constant current but I'm not 100% sure, so I thought I would ask.

I think I might use a LM3404 to create the constant current driver but I'm not sure.

Yes, if you are using low-side current sensing and PWM, the measured output voltage at the top of the LED string would just drop a bit if one of the LEDs shorted. BTW, a good product design would sense this lower high-side voltage, and the uC in the module would report the LED failure up the network management chain to request a replacement... :smile:
 

1. What causes a high power LED to short in a LED series string?

A high power LED can short in a LED series string due to various reasons such as manufacturing defects, excessive heat, overvoltage, or excessive current. It can also happen if the LED is damaged during installation or if there is a faulty connection.

2. What are the potential consequences of a high power LED shorting in a LED series string?

If a high power LED shorts in a LED series string, it can cause the entire string to fail. This can result in a loss of light output, reduced efficiency, and potential damage to the other LEDs in the string. It can also pose a safety hazard if the short causes overheating or electrical issues.

3. Can a high power LED short in a LED series string be fixed?

In most cases, a high power LED short in a LED series string cannot be fixed. Once the LED has shorted, it will need to be replaced. However, it is important to identify and address the underlying cause of the short to prevent it from happening again in the future.

4. How can I prevent a high power LED from shorting in a LED series string?

To prevent a high power LED from shorting in a LED series string, it is important to use high-quality LEDs and properly install them according to manufacturer guidelines. It is also important to ensure that the voltage and current levels are within the recommended range for the LEDs. Regular maintenance and monitoring can also help to identify and address any potential issues before they cause a short.

5. What steps should I take if a high power LED shorts in a LED series string?

If a high power LED shorts in a LED series string, the first step is to disconnect the power source and identify the faulty LED. It should be replaced with a new LED of the same type and specifications. It is also important to check for any other potential issues that may have caused the short and address them accordingly. Additionally, the entire LED series string may need to be checked and possibly replaced if any other LEDs have been affected by the short.

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