Roles and Characteristics of Gates in MOSFETs

A MOSFET has three terminals: gate, drain, and source. Gate voltage is the voltage applied between the gate and the source, denoted as Vgs in the datasheet.
By applying a voltage between the gate and source of the MOSFET, the drain and source become conductive. However, the gate has a capacitance component, and the gate voltage rises while charging the capacitance. Therefore, the circuit that drives the gate must have the ability to supply or withdraw charge from the capacitor.

* Here, N-channel, normally-off MOSFET is assumed.

Differences between SiC MOSFETs and Si MOSFETs

SiC MOSFETs have different characteristics from Si.
For example, if you compare the Si and SiC datasheets of 1200V MOSFETs, you will notice that the maximum rating of the gate-to-source voltage, Vgs, is different.

Microchip's Si MOSFET APT12057LLG has a maximum Vgs rating of +/-30V, while the same SiC-MOSFET MSC025SMA120B has a maximum rating of +23V/-10V. The voltage applied to the gate in actual use should not exceed this range, including surges.
You may have noticed that SiC has a lower rating on the negative side than Si, but this is a feature of SiC devices themselves, and I hope that you will become familiar with it.

What about SiC from Microchip?

The Vgs rating of the SiC-MOSFET MSC025SMA120B is "+23V/-10V". If you flip through the data sheet, there is a column called Test Conditions next to each characteristic value, and some numerical values are listed. For example, in the on-resistance column, it says "Vgs=+20V, ID=40A". This indicates that the stated on-resistance is the value at Vgs=+20V and ID=40A. If you actually want to use it near this on-resistance, you need a Vgs of +20V.
Microchip's application note states that "20V is recommended, and on-resistance increases at 18V or less", so please refer to it.

Micronote 1826: Microsemi SiC MOSFETs Design Recommendations

Although the gate drive of SiC-MOSFET is slightly different from that of silicon MOSFET, the basic concept of driving the MOS gate remains the same.

Microchip's SiC device products are developed for 700V, 1200V, and 1700V, and in addition to discrete SiC MOSFETs and Schottky Diodes, we have a large lineup of products especially for SiC power modules, and we also offer gate driver boards for modules. doing.
I would like to introduce SiC power module products in the future.

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