Controlling LED drivers with an Uno R3

Hello all,

I am designing a circuit that would need to power a group (3-6 LEDs) of SMD2835s. Each LED requires about 60ma and runs at about 3v. I know that I won’t be able to power the LEDs directly through the board but I was thinking that I could control them by adjusting the PWM of the LED through an external LED Driver. Has anyone ever tried this? Any suggestions for LED drivers?

Hi, more info please. Is this an rgb led strip? 60mA per led sounds high, unless that is 20mA each for r, g & b elements within the rgb leds.

If this is an led strip with 6 rgb leds, it will need a 12V supply and draw about 40mA each for the r, g & b channels. The led voltage is irrelavent because the strip will have the appropriate series resistors built-in. An ordinary npn transistor for each channel (eg. Bc337) will be fine. Drive the bases with pwm ouputs via 330R resistors.

Paul

I won’t be using a light strip and the SMDs I will be using are your basic white LEDs. SMDs generally run at higher currents than your typical 5mm LEDs but can’t be run at the currents used by high powr LEDs. They are considered mid-power LEDs.

jshields:
I won't be using a light strip and the SMDs I will be using are your basic white LEDs. SMDs generally run at higher currents than your typical 5mm LEDs but can't be run at the currents used by high powr LEDs. They are considered mid-power LEDs.

Not familliar with these. All the 2835 leds i have encountered have max current of around 20mA. Do you have a link to the data sheet? Do these medium-power leds need constant current drivers?

2835 SMD LEDs are slightly bigger than normal SMD LEDs , and run indeed on 60mA (max).
I have about 1000 of them in the ceiling lights in my house.
3-6 of them (360mA) could be powered from e.g. an Uno's 5volt supply (if the voltage on the DC jack is right).
Six current limiting resistors and a logic mosfet could PWM-dim them.
You could also use several small transistors for one or two LEDs, and several PWM outputs.
Leo..