I have been trying to get an ATMega32 to drive a motor via PWM through a MOSFET. After some trouble, I decided to isolate the MOSFET on a separate breadboard, take the PWM and everything else out of the equation, and play around with it to see if it is the source of my frustration.
I think I must be wrong about this, but here's what I found...
If you're using a power source, lets say a 9v battery, I'll call it BatteryA, for your Drain/Source to drive something, you would connect the gate to BatteryA's +ve to get the MOSFET going, then connect the gate to BatteryA's -ve to shut the MOSFET off.
If you're using two separate power sources, lets say the same 9v from before, BatteryA, and another power source, lets say another 9v, BatteryB, things don't work the same. If BatteryA is powering your Drain/Source, you cannot use BatteryB's +ve or -ve to turn the MOSFET on and off.
Is that correct or am I going nuts? Is this a simple rule of MOSFETs that I've overlooked?
I am trying to use a separate battery pack to drive the motors, while using the uC to drive the gate. But because the uC is using a different power supply(going to the gate) than the motors, which are connected to the Drain/Source, the MOSFET is not turning on.
I think I must be wrong about this, but here's what I found...
If you're using a power source, lets say a 9v battery, I'll call it BatteryA, for your Drain/Source to drive something, you would connect the gate to BatteryA's +ve to get the MOSFET going, then connect the gate to BatteryA's -ve to shut the MOSFET off.
If you're using two separate power sources, lets say the same 9v from before, BatteryA, and another power source, lets say another 9v, BatteryB, things don't work the same. If BatteryA is powering your Drain/Source, you cannot use BatteryB's +ve or -ve to turn the MOSFET on and off.
Is that correct or am I going nuts? Is this a simple rule of MOSFETs that I've overlooked?
I am trying to use a separate battery pack to drive the motors, while using the uC to drive the gate. But because the uC is using a different power supply(going to the gate) than the motors, which are connected to the Drain/Source, the MOSFET is not turning on.