Analog vs TTL/PWM laser power

I just noticed that the Ruida controller manages the laser PSU via the TTL/PWM input. Both the controller and PSU have an Analog control. Has anybody used analog instead of PWM? Any difference in behavior?


PWM is frequently used to produce an analog voltage. It just needs to be filtered (resistance + capacitor).

You can chech here to understand.

R should be as small as possible compared to input impedance (If input impedance is 100K, 4.7K is 1/20 of input impedance, that’s ok !), and C computed accordingly to needs.

With 1uf 4.7K, cut frequencey will be F = 1/ (2PiRC) = 33Hz

The output analog voltage will be same amplitude (ie : 0 > 5V) as the ttl value. It TTL output is 3.3V, analog voltage will be from 0 > 3.3V.

If Ruida analog input is alredy filtered (integrated R+C), then you can use a PWM. The most important thing will be to produce a PWM frequency adapted to the filter. You can also add a filter with a simple R+C calculated by you own.


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