What is a Logic Level MOSFET?

Ryan_2724 · October 15, 2024, 10:31pm

What is a Logic Level MOSFET?

Some of DigiKey’s FETs, MOSFETs have a “Logic Level Gate”.

Logic Level Gate MOSFET Drive Voltages

What are these and what are they used for?

A Logic Level MOSFET indicates the device can be driven with “logic level” voltage, which typically was referred to as TTL (Transistor-Transistor Logic). “Logic level” voltages have become smaller over the years due to the use of advanced MOSFETS instead of the use of true TTL. You will notice each will have their own specified logic level voltage listed, or their “Drive”.

These are best used for high-speed switching since these are known to have low input capacitance or a low gate-charge, yet minimizing the on-state resistance (RDS(ON)) to maintain superior switching performance making them ideal for high-efficiency power management applications. Sometimes referred to as “gate drivers” since they are designed to accept logic-level control signals, such as from an Arduino, and provide what is effectively an amplified form more suitable for driving a higher voltage load, or large, high-voltage FETs. The advanced MOSFET technology commonly use Enhancement-Mode, or Trench technology.

Driving Parameters

Although the drive voltage is the nominal rating to “drive” or turn-on the device, there is some tolerance. For example, the “Absolute Maximum Gate-Source Voltage” will be listed in the datasheet, which is the absolute maximum voltage that can be applied to the gate in reference to the source, commonly of some magnitude higher.

There is also what is called the “Gate Threshold Voltage” expressed as “Vth”, which is the voltage applied between gate and source that causes the drain current (ID) to be specified under a certain value. Then, for normal switching operation, VGS(ON) must be higher than Vth, and VGS(OFF) must be lower than Vth. This relationship can be expressed as:
VGS(OFF) < Vth < VGS(ON)

Take this into consideration when using the device and refer to item specific datasheet for its exact driving parameters and other specifications.

Related Topics

Guide to Selecting and Controlling a MOSFET for 3.3 VDC Logic Applications

Applicable Part Numbers

2156-NDS356AP-NB8L005A-488-ND	NDS356AP-NB8L005A
2156-NDS356AP-NB8L005A-600039-ND	NDS356AP-NB8L005A
2832-FDS6690A-NBNP006TR-ND	FDS6690A-NBNP006
2156-FDS6690A-NBNP006-600039-ND	FDS6690A-NBNP006
2156-RFP30N6LER4541-ND	RFP30N6LER4541
2156-HUFA76419D3ST-ND	HUFA76419D3ST
2156-RF1S17N06LSM-ND	RF1S17N06LSM
448-ISZ0901NLSATMA1TR-ND,448-ISZ0901NLSATMA1CT-ND,448-ISZ0901NLSATMA1DKR-ND,2156-ISZ0901NLSATMA1-ND	ISZ0901NLSATMA1
2156-BUK964R2-55B/C-ND	BUK964R2-55B/C
448-BSC0403NSATMA1TR-ND,448-BSC0403NSATMA1CT-ND	BSC0403NSATMA1
2156-BUK7618-55/C,118-ND	BUK7618-55/C,118
2832-FDS6685-NBCM003ATR-ND	FDS6685-NBCM003A
2156-RF1S15N08L-ND	RF1S15N08L
448-ISZ0501NLSATMA1TR-ND,448-ISZ0501NLSATMA1CT-ND,448-ISZ0501NLSATMA1DKR-ND	ISZ0501NLSATMA1

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What is a Logic Level MOSFET?