I want to create a relatively simple voltage controlled current source with a 3.3V micro controller. I have found THIS circuit and it seems to be what I need. The problem is it is designed for 0 to 5V.
So here are my questions and my research so far:
Question 1) Do you think a simpler solution exists (fewer parts, updated parts, etc.)?
Research 1) I can go with a single chip solution, something like LT3092 But, is that chip can be controlled by a microcontroller?
Question 2) What should I change in the schematic to make it 3.3V?
Research 2) In original circuit, 0V gives 0A and 5V give 100mA, so if I do not change anything in this schematic, 3.3V will give around 66mA. I guess it has to do with the pulldown resistor at the first input which forms a voltage divider?
Question 3) What should be changed if required maximum current is 200mA?
Research 3) It will be probably the internal resistance of the PFET at the output that limits the current, right? then, will I need more voltage at its input or I should change it with another PFET?
I am asking these questions to learn how the original circuit works, e.g.:
- What is the role of those 100pF capacitors?
- Why are the feedback resistors 10k?