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About the voltage and components of the lumen lamp

We need a special lamp, but the official lamp currently does not meet our needs, so we made a piece and a program based on the schematic diagram provided by the community. We found that the actual performance of the A6211 driver in the circuit diagram is very interesting. In the forced lighting mode, when we input a voltage of 7V, the voltage at both ends of the LED is about 6V, when the input voltage is 12V, the voltage at both ends of the LED is about 10.64V, when the input voltage is 14V, the voltage at both ends of the LED is about 6V. It is about 12.87V, and when the input voltage is 25V, the voltage at both ends of the LED is 23.6V. According to experiments, it is found that the voltage output from A6211 to the LED is always 1.4V lower than the input power voltage.
I also noticed that CREE’s MKRAWT-00-0000-0B00H4051 was used in the community’s lumen lamp. I learned from the data sheet that the lamp bead is powered by 6V. What makes me wonder is that the official power supply voltage is 7-48V. According to the experimental results, when the 48V power supply voltage is input, the output voltage of A6211 will reach 46.6V, and the rated voltage of the lamp bead is 6V, so theoretically speaking, when the 48V voltage is input, the output voltage of the A6211 drive is much higher than 6V. I feel that exceeding so much will destroy the lamp beads, so we did not install the lamp beads.
Our work has stalled because of this problem. Has anyone noticed this problem? How to solve this problem? In other words, this is a normal phenomenon. Will the system work normally when we connect the lamp beads to the circuit?

Are you measuring the voltage output of the A6211 with an LED installed or with no LED installed?

The A6211 is a constant current controller, it will adjust it’s voltage output to the LED to achieve the desired current. This is why it’s safe to apply 48V to the lumen device, the A6211 will limit the current to the LED to protect it.

Hi Jacob,
I also found this problem yesterday. I read the manual carefully and found that the A6211 chip uses current to control the LED lighting. Can I think that the chip will output an appropriate voltage to the LED by itself? I only need to adjust the output current through a small resistance. I noticed that the official lamp bead is 6v 2500ma, and this kind of lamp bead is not convenient to buy in our country. On the contrary, the 12v 1250ma version is very convenient to buy here, so we changed the lamp bead to 12v, but we connected After the system, it was found that the LED can reach the maximum brightness when the system input voltage reaches 14v. I just found out that I had forgotten to adjust the control resistance, so I calculated the resistance value according to the formula in the manual, and finally bought a 0.16Ω resistor, which is much larger than the official 0.082Ω. Is it useful for me to do this? Can the 12v LED be used normally after changing the resistance?

The voltage does not matter as each LED has a specified Current it can cope with. e.g. most standard white HighPower LED can handle 700 mA. But others may work with 350 mA or even several A. A BUCK LED Driver can handle a wide range of input voltage but constantly provides the neccesary mA oder A for the LED with a Voltage drop of 1 to 1,x V between input and output. This will only impact you if you like to run multiple LED’s in series as you input voltage must be e.g. 1,5 V above the total of the LED’s required Voltage.

Hi,Thomas
Thank you for your answer. The control resistor I bought has just arrived and I am trying to adjust the current of the entire system. I connected the 6v LED to the system and it works well, I am trying to use 12v LED by adjusting the resistance