Skip to main content
Electrical Engineering

Return to Question

deleted 1 character in body; edited title
Source Link
JRE
JRE
  • 73.5k
  • 10
  • 112
  • 194

LED Lamplamp - connecting LEDs in parallel

I have a question about LED lamp:

enter image description here Quantum Board

It has 16 strings of LEDs connected in parallel. Each string consist of 18 LEDs connected in serialseries. It's supplied with constant current source (with max current 2800mA, what is much more than safe current for single LED/led string).) I know that connecting LEDs in parallel is not the best solution because of imperfection of LEDs while manufacturing and as a result inequality of currents through every string. But I see that is quite common solution for such lamps. I have several assumption how it is possible:

  • using LEDs with very similar parameters (Vf), using LEDs with same binning. But actually, according to datasheet Samsung LM301B leds have 1V of Vf variation even inside every binning group. Possible in practice this variation is much lower.
  • very good thermal dissipation due to metal-core PCB

Could anyone explain how does it workworks? Are my suggestions the keys for the answer? Is putting seriala series current limiting resistor for every string and using CV source isa more robust solution and why not to do it in this way?

LED Lamp - connecting LEDs in parallel

I have a question about LED lamp:

enter image description here Quantum Board

It has 16 strings of LEDs connected in parallel. Each string consist of 18 LEDs connected in serial. It's supplied with constant current source (with max current 2800mA, what is much more than safe current for single LED/led string). I know that connecting LEDs in parallel is not the best solution because of imperfection of LEDs while manufacturing and as a result inequality of currents through every string. But I see that is quite common solution for such lamps. I have several assumption how it is possible:

  • using LEDs with very similar parameters (Vf), using LEDs with same binning. But actually, according to datasheet Samsung LM301B leds have 1V of Vf variation even inside every binning group. Possible in practice this variation is much lower.
  • very good thermal dissipation due to metal-core PCB

Could anyone explain how does it work? Are my suggestions the keys for the answer? Is putting serial current limiting resistor for every string and using CV source is more robust solution and why not to do it in this way?

LED lamp - connecting LEDs in parallel

I have a question about LED lamp:

enter image description here Quantum Board

It has 16 strings of LEDs connected in parallel. Each string consist of 18 LEDs connected in series. It's supplied with constant current source (with max current 2800mA, what is much more than safe current for single LED/led string.) I know that connecting LEDs in parallel is not the best solution because of imperfection of LEDs while manufacturing and as a result inequality of currents through every string. But I see that is quite common solution for such lamps. I have several assumption how it is possible:

  • using LEDs with very similar parameters (Vf), using LEDs with same binning. But actually, according to datasheet Samsung LM301B leds have 1V of Vf variation even inside every binning group. Possible in practice this variation is much lower.
  • very good thermal dissipation due to metal-core PCB

Could anyone explain how does it works? Are my suggestions the keys for the answer? Is putting a series current limiting resistor for every string and using CV source a more robust solution and why not do it in this way?

Source Link
plumbum_by
plumbum_by
  • 109
  • 2
  • 9

LED Lamp - connecting LEDs in parallel

I have a question about LED lamp:

enter image description here Quantum Board

It has 16 strings of LEDs connected in parallel. Each string consist of 18 LEDs connected in serial. It's supplied with constant current source (with max current 2800mA, what is much more than safe current for single LED/led string). I know that connecting LEDs in parallel is not the best solution because of imperfection of LEDs while manufacturing and as a result inequality of currents through every string. But I see that is quite common solution for such lamps. I have several assumption how it is possible:

  • using LEDs with very similar parameters (Vf), using LEDs with same binning. But actually, according to datasheet Samsung LM301B leds have 1V of Vf variation even inside every binning group. Possible in practice this variation is much lower.
  • very good thermal dissipation due to metal-core PCB

Could anyone explain how does it work? Are my suggestions the keys for the answer? Is putting serial current limiting resistor for every string and using CV source is more robust solution and why not to do it in this way?