I'm planning to use a circuit as a laser diode driver shown in this datasheet. It is not for production, just for lab test purposes, but I would like to obtain fair accuracy and be sure the circuit won't exceed its max. limits.
The laser diode specs are follows (link is not kept alive by the vendor so I share the screenshots):
Above, D1 and D2 are there to mimic the laser diode.
I want to control the laser current between 0 to 500 mA by the 10 kΩ Rpot. I will set the laser current and leave it, so I don't any switching or modulation.
My question are:
Can the transistor (BD139) handle a continuous current of 500 mA?
LTspice simulation shows the following plot for 0 < Rpot < 10 kΩ:
For a larger input the current goes beyond 1A. How can I guarantee that the laser diode would not get damaged? Should I limit the voltage across it or just be sure the current does not exceed 500 mA?
The diode metal case is tied to the anode so as an alternative circuit: