I’m a newbie to circuit simulation and KiCAD 8. I would appreciate it if anyone can give me a hand solving this problem. I’m trying to level down a 3.6V and 37mA to 3.3V with almost the same current level, so it can be fed to other ICs further down the circuit. I was told that I need to use a op-amp and NPN transistor instead of just using a simple voltage regulator in SMD form which would do the same job in reality.
I’d run the simulation for many times, but the current and voltage are not what’s expected to be.
So, please tell me if this configuration will fulfil the purpose of leveling down voltage, if yes, why the results in simulation is not given? if no, where do you think is the issue on the circuit?
One reason is the Base to emitter voltage drop of an NPN transistor. You would need 3.9V on the base to get 3.3V on the emitter.
Another reason is the output range of the opamp. I guess an LM358 needs about 1.5V “headroom” on the top end of the power supply, I.e. with a 3.6V power supply it’s output will never go above 2.1V I have not checked whether an LM358 will even work at all on a 3.6V power supply.
I assume this is for powering a microcontroller from a Li-Ion battery. Both those batteries and 3.3V logic are very common and I guess there are specialized IC’s that can do this. Another option is to use a microcontroller (or logic) that can work with a 5V power supply. Nearly all 5V microcontrollers have a wide operating range. For example from 5.5V (sometimes 6V) down to 2.5V or less.
And it’s also off topic, as ML9104 already mentioned. This forum is for questions around how KiCad work, and not for how electronics work. For that there are other forums.
