This is a 20W Power LED driver, capable to provide power and drive one or more LEDs. It is basically a current source made tiny. A lot of them are available on Hackaday or in the world, but I didn't find a ready to use board with such specifications that I wanted to have.

From pictures you can see that the revision is not the first: few attempts were made in the past to reach the actual characteristics. And now, with a newer one, you can actually see the size improvement.

So, boards are back to stock, but with a better revision. This is the second one, with a real coin size form factor, while all the other characteristics are kept unchanged. I made this change because I found it more convenient when placing more than 3 boards inside a box (like for making an RGB high power led driver), due to better organization of the cables, specially if used with a 100 mil plug connector.

I plan to use this LED driver on my other projects, as a companion board for anything I can imagine.

Product summary

• Technology: Texas Instruments LM3405 switching buck regulator
• Input voltage: 3V to 20V
• Output voltage (LED Vf): 0.3V to 20V
• Sourced current: up to 1A on request (set to default 570mA)
• Size (rev. 2): 24mm x 19mm
• Efficiency: 90%
• Operating Temperature: -40°C to 60°C

• Safety features:

  • Short circuit immune

  • Open circuit immune

  • Safe state (off) when no control is applied

• Overtemperature protected

• Control features: PWM control: voltage swing from <0.4V to >1.8V up to input voltage, max suggested PWM frequency 5kHz

Source files

Any external link is shown in the project's links.

How to use it

The driver has 3 input pins

• VIN: the input voltage
• GND: ground
• EN/PWM: the control pin

Any board handling any type of digital signal can be used to drive the EN pin. Any signal lower that 0.4V result in a full off driver; any signal higher that 1.8V fully turns on it. This means that PWM can be used, of any voltage swing up to the power supply!

The output is made by 2 pins

• LED anode
• LED cathode

Just connect the LED respecting the polarity, or the LED can fail (read the datasheet of your power LED!).

Setting the current

Assuming that the input voltage is respected, the driver can light any LED which is designed to take around 700mA. A sense resistor is used to set this current: a different sensing value can be used to adjust the output current.

I made this resistor fixed for a security reason: knowing myself, I eventually change the resistor and burn the LED, if it wasn't fixed. It can be dimmed through the EN pin! If the LED cannot take current peaks of the rated current, the sense resistor can be changed (also upon request).

With your help, buying these boards, I can work on a better versions: therefore suggestions/preferences are very very helpful!