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Which MOSFET is always on?
Mosfet is always on without gate connected.
At what voltage does the MOSFET turn on?
1) a Vgs between 3-5V will turn on the MOSFET. 2) Vgs must be greater than 5V, since that is the minimum voltage required to turn on the MOSFET.
What is the condition of saturation?
The condition for saturation is Vds = Vgs – Vt, since at this point IR drop in the channel equals the effective gate to channel voltage at the drain.
How do you turn off a MOSFET circuit?
Before any charge is injected into the gate, it is fully turned off, with no current able to flow from the drain to the source. As charge is injected into the gate, more and more current is able to flow from drain to source, until the gate capacitance is fully charged. All charge must then be removed from the gate to turn the MOSFET off.
How is the switching speed of a MOSFET determined?
As charge is injected into the gate, more and more current is able to flow from drain to source, until the gate capacitance is fully charged. All charge must then be removed from the gate to turn the MOSFET off. Determining the time it takes to charge and discharge the gate helps to determine the maximum switching speed of a MOSFET circuit.
What are the resistors in a MOSFET circuit?
R1 is the gate resistor, limiting the amount of current and preventing any ringing on the gate. R2 is a 10K pulldown resistor, ensuring the MOSFET is always in a known state. Q1 is a logic-level MOSFET, an appropriate choice for controlling an indicator LED at 10s of milliamps.
What’s the difference between normal and logic level MOSFET?
A “standard” or “normal” MOSFET will require around 10V to ensure it is fully “on”. At 10V the Rds will typically be at its minimum value for the entire voltage range. A “logic-level” MOSFET is a relatively new MOSFET idea. Instead of requiring 10V to turn on, they may only require 5V or even less.