Video: isolated gate drivers & noise immunity
In power electronics, isolated gate drivers are used to drive IGBT and Power MOSFETs. With the emergence of SiC and GaN, power electronics are operating at higher frequencies to increase system efficiency and reduce system size and costs. The increase in frequency results in higher switching noise or commonly known as common mode transient, dv/dt.
This noise can be coupled to the input and cause wrong output at the power semiconductors. One important specification of the gate driver is its ability to reject high common mode transient. This specification is normally termed as CMTI, Common Mode Transient Immunity. To meet high frequency applications when using SiC or GaN MOSFET, it is recommended to have a CMTI of at least 100kV/µs. As the frequency increases, the CMTI is expected to double to 200 kV/µs.
Two isolated gate drivers that are recommended for SiC and GaN and have a CMTI of over 100 kV/µs. They are the isolated driver Si827x series from Silicon Labs, and optocoupler ACPL-P349 from Broadcom. The Si827x series uses RF to transmit signal across isolation barriers, while the ACPL-P349 uses optical isolation. To find out more about both of these isolation drivers, watch the video below.