This article details our potential mistakes. Many users are not even aware that their light source is driven by a current generator, and if it fails, they tend to treat it as if it were a voltage-regulated power supply. Without knowing that a current-driven LED has much more limited options when it comes to replacing the power supply. Therefore, the issue is not that the user is unaware of the current-driven nature of their light source, but that in case of failure, they treat it as if it were a fixed voltage power supply.
For them, I have compiled the possible scenarios when they might want to deviate from the factory-designed drive parameters, to understand the consequences in advance.
The most important requirements:
- If a light source is designed for current-driven operation, it cannot be operated with a voltage-regulated power supply.
- The fundamental element of a current-driven power supply is the output current strength, e.g., 950 milliamps. This is similar to saying a voltage-regulated power supply is 12 Volts. In the former, the current does not change, while in the latter, the voltage does not change (under normal operating conditions).
- The second key element of a current-driven power supply is its voltage range, e.g., 36-50 Volts. This is similar to saying that a voltage-regulated power supply has a maximum output current of 5 Amps. So this represents a range from 0-5 Amps.
- You may have noticed that while the maximum current is specified for a voltage-regulated power supply because the minimum value is close to 0, the lower voltage value is also specified for current-driven power supplies because it is never 0 Volts. Therefore, the usability range of a current-driven power supply is almost always significantly smaller than that of a fixed voltage power supply. Moreover, while there are common voltage values for voltage-regulated power supplies (5 Volts, 12 Volts, 24 Volts, etc.), the variation is much greater for current-driven power supplies because there are no more common current values. Even LED panels of the same appearance and performance are rated for different currents by different manufacturers. Values can range from 350mA to 1150mA in 50mA steps in LED lighting technology, and none can be said to be a more general value.
- You can only drive your LED lamp, which requires current-driven operation, with the current strength for which it was designed. And the operating voltage specified by the manufacturer must be within the voltage range indicated on the power supply.
But let’s see what can happen if you break these requirements:
1. If a current-driven LED panel is powered by a power supply that is correct in terms of current but the LED panel’s voltage requirement is lower than the power supply’s operating voltage range, several scenarios are possible:
1. The LED panel will not work:
- This is the most likely scenario. Current-driven LED panels are designed for a specific voltage. If the power supply provides too high a voltage, the LEDs will not turn on.
- In some cases, the LEDs may flicker or dimly light before failing.
2. The LED panel overheats and fails:
- If the power supply provides a slightly higher voltage than the LED panel’s requirement, the LEDs may receive too much power, leading to overheating.
- Overheating shortens the lifespan of the LEDs and can cause permanent failure.
3. The LED panel might work, but its brightness may be reduced:
- This scenario is less likely. In some cases, LEDs can operate within a certain voltage range with a reduced brightness.
- If the power supply provides a not too high voltage, the LEDs may function, but their brightness will be lower than normal.
It may seem strange to conclude that if the LED panel receives a slightly higher voltage than necessary, the brightness will decrease instead of increasing.
- Generally, increasing the voltage increases power and brightness. However, this is not always the case with LEDs. The reason is that LEDs have a non-linear voltage-current characteristic.
- The voltage-current characteristic of LEDs shows that the current through the LED does not increase proportionally with the voltage. At low voltage, the current increases exponentially with voltage. However, as the voltage increases, the current increase slows down and eventually reaches saturation.
- If the power supply provides too high a voltage to the LED panel, the current through the LEDs will not continue to increase. Instead, the LEDs will receive too much power, leading to overheating. Overheating can reduce the brightness of the LEDs and shorten their lifespan.
- Additionally, current-driven LED panels have a built-in current limiter. This current limiter prevents excessive current from flowing through the LEDs, which could damage them. If the power supply provides too high a voltage to the LED panel, the current limiter will activate and reduce the current. This results in a decrease in brightness.
- Overall, due to the voltage-current characteristic of LED panels and the current limiter, too high a voltage does not increase brightness but can reduce it and damage the LEDs.
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2. If a current-driven LED panel is powered by a power supply that is correct in terms of current but the LED panel requires a higher voltage than the power supply’s operating voltage range, several scenarios are possible:
1. The LED panel will not work:
- This is the most likely scenario. Current-driven LED panels are designed for a specific voltage. If the power supply provides too low a voltage, the LEDs will not turn on.
- In some cases, the LEDs may flicker or dimly light before failing.
2. The LED panel overheats and fails:
- If the power supply provides a slightly lower voltage than the LED panel’s requirement, the LEDs will not receive enough power and will not function properly.
- This can lead to overheating, which shortens the lifespan of the LEDs and can cause permanent failure.
3. The LED panel might work, but its brightness may be reduced:
- This scenario is less likely. In some cases, LEDs can operate within a certain voltage range with a reduced brightness.
- If the power supply provides a not too low voltage, the LEDs may function, but their brightness will be lower than normal.
3. If a current-driven LED panel is powered by a power supply that delivers lower current than the LED panel requires, but the LED panel’s voltage requirement is correctly within the power supply’s operating voltage range, the following scenarios are possible:
1. The LED panel will operate with lower brightness:
- This is the most likely scenario. If the power supply cannot provide the LED panel’s required current, the LEDs will not light at full brightness.
- The reduction in brightness will be proportional to the decrease in current.
2. The LED panel overheats and fails:
- If the power supply delivers a significantly lower current than the LED panel requires, the LEDs may receive too much power due to the voltage, leading to overheating.
- Overheating shortens the lifespan of the LEDs and can cause permanent failure.
3. The LED panel might work, but its brightness may fluctuate:
- This scenario is less likely. In some cases, LEDs can operate within a certain current range with fluctuating brightness.
- If the power supply cannot provide a stable current, the brightness of the LEDs may fluctuate.
It is thought-provoking that “if the power supply delivers significantly lower current than the LED panel requires, the LEDs may receive too much power due to the voltage, leading to overheating.”
- This is because the voltage-current characteristic of LEDs is nonlinear. This means that the current through the LED does not increase proportionally with the voltage. Once the forward voltage is exceeded, the current increases exponentially with the voltage. However, as the voltage continues to rise, the current increase slows and eventually reaches saturation.
- If the power supply delivers significantly lower current than the LED panel requires, the LEDs will not receive sufficient current. This increases the voltage across the LEDs, as they try to maintain the current.
- However, the increase in voltage does not compensate for the decrease in current. The power (which is the product of voltage and current) will decrease. This leads to lower brightness of the LEDs.
- Furthermore, the increased voltage can cause overheating in the LEDs. This shortens the lifespan of the LEDs and can lead to permanent failure.
- However, in such cases, if the voltage increase requirement exceeds the power supply’s upper voltage limit, the LED panel will most likely not light up, thereby avoiding potential damage. If the LED panel’s increased voltage requirement remains below the power supply’s upper voltage limit, the power supply will accommodate it, increasing the likelihood of failure.
- Using an incorrect power supply can damage the LED panel even if the voltage requirement does not exceed the power supply’s upper voltage limit. This can be due to unstable voltage and current provided by the power supply. Unstable voltage and current can lead to overheating in the LEDs, which shortens their lifespan and leads to permanent failure.
- LEDs have a non-linear voltage-current characteristic. This means that the current through the LED does not increase proportionally with the voltage. At low voltage, the current increases exponentially with the voltage. However, as the voltage increases, the current increase slows down and eventually reaches saturation.
- If the power supply delivers too much current, the current through the LEDs will exceed the saturation current. This increased current leads to overheating in the LEDs. Overheating damages the structure of the LEDs, which shortens their lifespan and can lead to permanent failure.
- Additionally, excessive current can cause overloading in the power supply. This overload can shut down the power supply or damage its components.
- It is not recommended to use a power supply with a higher current rating than specified for the LED panel. Using an incorrect power supply can damage the LED panel, the power supply, shorten the lifespan of the LEDs, and be dangerous.
4. If a current-driven LED panel is powered by a power supply that delivers more current than the LED panel requires, but the LED panel’s voltage requirement is correctly within the power supply’s operating voltage range, then:
The LED panel will likely fail. This is because the excessive current leads to overheating in the LEDs, which shortens their lifespan and can lead to permanent failure.
Experimenting with current-driven power supplies should be avoided. Always use a power supply that meets the specifications of the LED panel. Using an incorrect power supply can damage the LED panel and be dangerous.