3A Constant Current Driver for DPSSL+SHG experiment

This CC driver is designed for DPSSL+SHG experiment


This is a very simple current source, I just use it to safely drive a common high power C-mount laser diode. Do not use this driver to drive any expensive diode because there isn’t any protection circuit in this schematic. And do not expect great drift and noise performance of this circuit. If you are looking for some precision choice, you may keep a look at my design specified for precision lasers.

The left part buffers the output from TL431A (a very cheap voltage standard), to give a stable voltage about 0.041V.

The center part charge a large capacitor through 10K resistor to form a RC circuit, providing soft start function to the driver.

The right part is a simple PI controlled constant current circuit, receive voltage signal from the potentiometer which set the current we want, get the feedback from 5 parallel current sensing resistors, drive a MOSFET to control the current.

In order to reduce the heat dissipate on the MOSFET, I use a DC-DC module to provide power a little bit higher than the Vf of the diode. This  method is not practical in precision driver because the DC-DC module will bring in terrible noise to the system.

Here are photos of the driver under test and the final PCB version.






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