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0-4A adjustable PWM/TTL Laser Driver

This is a laser driver based on Agastar’s original design usingSTMicroelectronics’ LED2001PHR high power LED driver. My design changes includes the use of more low-cost components, adds a optocoupler isolation for the PWM signal and the option to manually control the output current with a potentiometer.

Use it to drive LEDs or lasers. The driver also features a PWM input. A square wave on this input through a CNC driver or an Arduino controls the current available to the load. Current scaling is proportional to the duty cycle of the square wave. For e.g. a 25% duty cycle will allow only 25% of the full current to be available to the connected load.

If you wish to build this yourself, all the schematics, bill of materials and gerbers are available for download here. If OSHpark is your go-to destination for getting PCBs then here is the project link.

Download Gerber files here.

Setting the current limit

Current adjustment is easy. First connect a multimeter set to measure resistance across the POT terminals. Turn the trimmer all the way to its highest limit (around 1K). Now, connect the PWM input to a fixed 5V supply or the VIN pin (also available as the Fan+ output).

Connect a multimeter in series with the LED+ or the laser+ (best to set the current with an LED than a laser. Burning LEDs is way cheaper than a laser). Start turning the trimmer down till you see the current you want. I used 5 parallel strips of two 1W LEDs in series.

You can also use this LTSpice simulation to calculate the exact trimmer values for your output current.

Board layout and connect guide

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