Electronics > Projects, Designs, and Technical Stuff
14.4V ground reference for ADC
Arjunan M R:
--- Quote from: Simon on May 20, 2019, 03:34:00 pm ---I was refering to your current limits. This is usually done in analogue so reacts instantly. There are smart mosfets that will cut out in 1µs if overloaded. if the current limit does not react fast enough it can still damage stuff.
PWM DAC is easy. the output voltage will be the averaged PWM value, you use a low pass filter that has a cut off frequency 10-100 times lower than the PWM, simple matter of physics.
--- End quote ---
Yes when i simulated the circuit in lt spice i saw a big current spike eventhough i set the constant current.
It was lower than 1ms so i thought it doesn't matter.
Now i think it does matter.
Arjunan M R:
--- Quote from: Simon on May 20, 2019, 03:34:00 pm ---I was refering to your current limits. This is usually done in analogue so reacts instantly. There are smart mosfets that will cut out in 1µs if overloaded. if the current limit does not react fast enough it can still damage stuff.
PWM DAC is easy. the output voltage will be the averaged PWM value, you use a low pass filter that has a cut off frequency 10-100 times lower than the PWM, simple matter of physics.
--- End quote ---
Does adding an inductor before the current shunt help??
Arjunan M R:
--- Quote from: Simon on May 20, 2019, 03:34:00 pm ---I was refering to your current limits. This is usually done in analogue so reacts instantly. There are smart mosfets that will cut out in 1µs if overloaded. if the current limit does not react fast enough it can still damage stuff.
PWM DAC is easy. the output voltage will be the averaged PWM value, you use a low pass filter that has a cut off frequency 10-100 times lower than the PWM, simple matter of physics.
--- End quote ---
What can i do about it. I still need to use the DAC.
Simon:
--- Quote from: Arjunan M R on May 20, 2019, 03:51:00 pm ---
--- Quote from: Simon on May 20, 2019, 03:34:00 pm ---I was refering to your current limits. This is usually done in analogue so reacts instantly. There are smart mosfets that will cut out in 1µs if overloaded. if the current limit does not react fast enough it can still damage stuff.
PWM DAC is easy. the output voltage will be the averaged PWM value, you use a low pass filter that has a cut off frequency 10-100 times lower than the PWM, simple matter of physics.
--- End quote ---
Does adding an inductor before the current shunt help??
--- End quote ---
NO!
Simon:
--- Quote from: Arjunan M R on May 20, 2019, 03:52:47 pm ---
--- Quote from: Simon on May 20, 2019, 03:34:00 pm ---I was refering to your current limits. This is usually done in analogue so reacts instantly. There are smart mosfets that will cut out in 1µs if overloaded. if the current limit does not react fast enough it can still damage stuff.
PWM DAC is easy. the output voltage will be the averaged PWM value, you use a low pass filter that has a cut off frequency 10-100 times lower than the PWM, simple matter of physics.
--- End quote ---
What can i do about it. I still need to use the DAC.
--- End quote ---
You could learn what you are doing before making stuff up. You have done nothing but emphasize the cost has to be low yet you have thrown parts at this like there is no tomorrow. Why not do the simpler design first that you talked about.
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