I'm using an N-channel mosfet to supply power to a servo. The problem is that even with the gate set at low, I'm still getting some amount of voltage (~0.9V in a 5V system) coming through. Do I need a pull-down in case the pin is floating?
Here's the current schematic:
Answer
Yes, if you just tristate after pulling it high, then the gate will stay floating high. You either need a resistor to pull it down to ground or you need the input signal to drive it low.
The resistor can/should be relatively high valued compared to your input resistor to prevent excessive voltage drop when you have it set as a high input. You only have to drain the inherent capacitance on the MOSFET gate when you're pulling it low so even at a high resistance to ground the RC time constant is usually relatively short.
No comments:
Post a Comment