# Calculating the needed power and compatible driver specifics?

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G

#### Gone

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how to calculate the needed power to light up 6 cool white and 6 white HPL chip like this ?
what is the compatible driver specifics to light up 6 cool white and 6 white HPL chip like this ?

#### Lucien Nunes

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Esteemed
Arms
You have to decide whether you want a constant-current system with all the LEDs in series, or a constant-voltage system with them in parallel with ballast resistors. Constant current is more efficient but constant voltage more flexible e.g. if you want to switch them separately.

Assuming a constant current system, the two types have different current needs so you need two drivers. The LED current is the same as the driver current. The voltage compliance of the driver has to include the range of voltage stated on the LED multiplied by the number in series (in this case 6x the stated voltage)

The white LEDs need a constant current driver with an output current in the range of 350-580mA according to the brightness you want, and a voltage compliance of at least 18-21V (so an 18-32V unit would suit). The cool white LEDs need one with 600-1200mA output and 18-22V range minimum.

#### dogbob

DIY
If you want to power all 12 at once, you might as well put them all in series and drive them from a current-limited power supply. 5 watts at 3.5V is 1.4 amps, so you will be running the total string at somewhere around 1.4 amps for full brightness, less current for less brightness.

3.5V * 12 LEDs is 42V, so you will need a power supply capable of 42V at 1.4 amps, with adjustable current limit. Unfortunately, that's not a common voltage. Surplus printer power supplies put out roughly 32V and laptop power supplies put out roughly 20V. But if you look around, you'll find something that will work.

As an alternative, you could connect them as two strings of 6 LEDs and power them from a surplus laptop power supply with series resistors for current limiting. I would try putting 2 ohms in series with each string of 6 LEDs. 2 ohms * 1.4 amps = 2.8V drop. If that's too dim, you might lower it to 1 ohm but don't go any lower.

42V is considered relatively safe, so as long as you are reasonably careful, you can wire this yourself. Anything above 48V is considered high voltage and needs special precautions.

Even though they are LEDs, they will still waste some energy, and that will be heat in the aluminum baseplate. The common solution is to attach them to a piece of aluminum which will dissipate the heat. If you don't do that, they will get very hot and fail.

OP
G

#### Gone

i wanted to light up 12 all of them with series circuit board without burning the HPL chips
i want to know what is the suitable driver specification to light 12 all of them
Also is 42V at 1.4 amps the maximum power to light 12 all of them?
down below is my circuit board for the HPL LED chip

Is this driver too much to light 12 all of them?
By the way i ever tried to lighten 12 all of them with this driver but the HPL LED chip starts flickering and won't light up after the second time

also what kind of driver do i need to light up 12 HPL LED chip safely without failing?

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#### Lucien Nunes

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Read carefully my post #2! It tells the correct drivers to use. The driver in your picture seems to be 42V maximum which is barely enough for all 12 LEDs so I would not be surprised if it was unstable. You need more like 48V for all 12. This, combined with the different current ratings of the two different types, is why I suggested two different drivers.

OP
G

#### Gone

so i my driver is underpowered to light up the 12 HPL LED chip ?

so what is the best power rating to light up 12 all of them at once?

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