MOSFET Gate Driver Circuit

The MOSFET gate driver is a power amplifier that is used to control the voltage between the Gate and Source (Vgs) and Gate Current. The MOSFET has a depletion region. According to the size of the depletion region, the MOSFET behaves like in its ON state or its OFF state. The size of the depletion region depends on the number of charges gathered in the Gate terminal. Therefore the MOSFET forms a capacitor which is called a Gate Capacitor.

Therefore transistor takes a certain time to switch from non-conducting mode to conducting mode. So the MOSFET subject to a considerably higher voltage and higher current.  It causes to generate heat in the transistor and  be enough to destroy the transistor (Desaturation fault)
The transition time of the MOSFET which related to the transition between conducting mode and conducting mode can be reduced by using higher Gate Current (Switching Current).
The Gate Driver can be used to control the gate current. Apart from that isolation between the high voltage side and the low voltage is also done by it.

The MOSFET gate driver is a power amplifier used to control the voltage between the gate and source  (Vgs) , as well as the gate current. The operation of a MOSFET depends on the depletion region within the device. Depending on the size of this region, the MOSFET operates either in its ON or OFF state. The size of the depletion region is influenced by the amount of charge accumulated at the gate terminal, effectively forming a capacitor known as the gate capacitance.

As a result, the MOSFET requires a certain amount of time to switch from the non-conducting state to the conducting state. During this transition period, the MOSFET can be subjected to significantly high voltages and currents, which may lead to heat generation within the device—potentially enough to damage or destroy it. This failure mode is commonly referred to as a desaturation fault.

The switching time, which refers to the duration required for the MOSFET to transition between its ON and OFF states, can be minimized by applying a higher gate current (switching current). A gate driver is used to provide this current and to control the gate voltage effectively. In addition to supplying the required gate current, the gate driver also provides electrical isolation between the high-voltage side and the low-voltage control circuitry.

The following gate driver circuit is designed by using TLP250 (datasheet) to drive IRFP250 MOSFETs (datasheet). Note that this design does not include any fault detection mechanisms.

Schematic

Components

• U1 -TLP250
• IC1-LM7815T
• B1-KBU8B (datasheet) 
• R1-120
• R2-10 1W
• R3-1k
• R4-1k
• C1-470uF 50V
• C2-Optional
• C3-0.1uF
• LED1-Red 3mm

The PCB layout of the gate driver is shown below and it's designed according to the recommended layouts.

PCB Layout

If this is used in a three-phase inverter, four separate transformers are required to power the gate drivers. The low-side MOSFETs (those connected to the negative bus bar) can be powered using a single transformer. The remaining three transformers are used individually to power each of the high-side MOSFETs.

Eagle Schematic can be downloaded here  and PCB layout can be downloaded here