Hi,
I was wondering if someone could help. I am building a programmable negative constant current source. The idea is as follows:
DAC controlled from a microcontroller fed into the non inverting input of an opamp. The opamp has split supplies +/-5V. The out put of the opamp drives the gare of a n channel MOSFET. The drain is at 0V and the source is connected to a 100K resistor then to the load. The resistor at the source is fed back into the inverting feedback pin of the opamp. The idea being that whatever the DAC input is will be seen at the feedback pin, so I equals DAC/R.
Will this circuit work. I have the drain more positive than the source (which I think will be negative) or do I need to use a p channel MOSFET?
Any help will be appreciated.
Thanks,
Rajinder
I was wondering if someone could help. I am building a programmable negative constant current source. The idea is as follows:
DAC controlled from a microcontroller fed into the non inverting input of an opamp. The opamp has split supplies +/-5V. The out put of the opamp drives the gare of a n channel MOSFET. The drain is at 0V and the source is connected to a 100K resistor then to the load. The resistor at the source is fed back into the inverting feedback pin of the opamp. The idea being that whatever the DAC input is will be seen at the feedback pin, so I equals DAC/R.
Will this circuit work. I have the drain more positive than the source (which I think will be negative) or do I need to use a p channel MOSFET?
Any help will be appreciated.
Thanks,
Rajinder