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Giannis, that's the signal of the totem pole, it's not the signal of the buck converter. This is the signal of the step down, I already mention LM311 and LM317 just to point the difference vs DC-DC converters.

Cyparagon, actually, LM317's output signal is an PWM signal, not an non sine signal, and I'm using a certified power supply, buy don't worry I'll be posting the results with NUMB44-V2, so we can debate with the reallity, your points.

Giannis_TDM, LM311 also turn on and off the diode, as I said, you're killing the diode.

Giannis-TDM, you're right quality and complex things are more expensive than single modules, I assume that it's better for most of the people just buy things, and don't design; as I said to you, I'll be posting images of the laser results, base on the NUMB44-V2, so we can compare reality and...

Yes CH-1 is the PWM signal, CH2 is the signal of the laser. In the following picture, CH-2 is the totem pole signal. The feed back helps to compensate that 4% lost 'cause the amplification of the BJT.

Cyparagon, an LM311 turns on and off your diode, leading your dutty cycle, that affects the quality and the life of your product (laser diode), an stepdown provide a non discontinuous signal, that's the main difference, using the totem pole you have a better fall of you PWM, STM32 resolution is...

That's the point, an step down circuit can establish a limit voltage (without taking in consideration the losses in the circuit), a laser diode is that, A DIODE, and diodes works depending the voltage that is provide for the source, in the case of the graphic you are providen 5V to the diode...

That's the signal at 60% of dutty cicle, provide from the microcontroller (in this case a STM32), the dutty cicle limits the voltage provide to the diode. I'm using a HANTEK, sorry for the resolution.

That's a good question, actually if you visite the blog you'll find that's not necessary a feedback loop for the laser control, that's optional, this is a basic circuit, but yes you are right, the 40KHz signal reduce the size of the inductor that you need, at the same time, using power simulator...

This is a DC-DC stepdown circuit for laser control (better option than a LM311), at engineering level, it's based on texas instrument documentation, for testing proves I used three 9W 1Ohm resistors in parallel, the elementrical characteristics prove to work well with the laser load. There you...