Why are the MOSFET transistors simpler to drive?
The MOSFET transistors are simpler to drive because their control electrode is isolated from the current conducting silicon, therefore a continuous ON current is not required. Once the MOSFET transistors are turned-on, their drive current is practically zero.
Do you need threshold voltage to turn on MOSFET?
There needs to be a certain gate-to-source voltage, called threshold voltage, in order for the MOSFET to turn on. However the isolated gate-electrode of the MOSFET forms a capacitor, called gate capacitor, which must be charged or discharged each time the MOSFET is switched on or off respectively .
Why does a MOSFET need a drain source?
The MOSFET needs to be able to handle the peak current of the circuit keeping in mind that the current rating decreases with increasing temperature. The Drain-Source voltage of the MOSFET has to handle the maximum voltage supplied. Also this voltage rating varies with the temperature.
How big of a pulse modulated signal do you need for a MOSFET?
A 3.3V or 5V signal, which is the maximum of a pulse modulated signal delivered by a microcontroller, is often not enough for the MOSFET. Usually 8-12V is required to fully turn on the MOSFET. There is also a third issue: a switching MOSFET can cause a back-current from the gate back to the driving circuit.
Why is isolation important in a power MOSFET?
Isolation is usually a requirement of safety norms and operating conditions when the switch voltage floats with respect to ground. This paper highlights a specific characteristic of the Power MOSFET which is often neglected: the use of the gate input capacitance as an ON state memory.
When do you need an isolated power switch?
INTRODUCTION Isolated power switches are often used in motor drives, uninterruptible power supplies and AC switches. Isolation is usually a requirement of safety norms and operating conditions when the switch voltage floats with respect to ground.