Hello,
I am trying out a circuit for a constant current load for discharging Lithium batteries using mosfet and op-amp.
I am using LM358 for op-amp and IRFZ44N for the mosfet from a 5v (500mA max) power supply.
First I tried a circuit like this (file : circuit_1):
Here, I got the output of the op-amp as around 3.7v which is not enough to switch the mosfet completely. Moreover, as you can see, I was using the same power source for powering mosfet as well as to connect the mosfet drain. I observed that very little current was flowing and mosfet became very hot.
I have a few questions here:
Can I use a single transistor to drive the mosfet? Most of the circuits I encountered had the mosfet gate connected to the collector of the BJT where the logic will be reversed (mosfet OFF when op-amp is ON).
Is it possible to connect the mosfet to the low-side (emitter) of the BJT and switch it ON?
Thanks.