Efficient SiC MOSFET gate protection with asymmetric TVS diodes

With the SMFA series of asymmetrical TVS diodes from Littelfuse, Rutronik presents an innovative solution for greater resilience of SiC MOSFET gate driver circuits. The diodes have been specially designed to protect the sensitive gate structures from negative and positive overvoltages and can, therefore, replace two separate TVS diodes. This allows designs that are cost-effective and space-saving while minimising parasitic effects. They are particularly suited to fast-switching SiC applications that demand a power supply for AI/data centres, semiconductor/industrial equipment, or e-mobility infrastructure. They are available in tape and reel standard packaging in various versions.

SiC MOSFETs typically have a particularly lower negative than positive gate voltage. Therefore, asymmetric protection with two separate TVS diodes was previously needed, which took up more space in the design. The company offers the integrated asymmetric, bidirectional TVS diode Type SMFA to meet this challenge.

The components impress with low inductance and exceptional clamping capability. They fulfil the requirements of IEC 61000-4-2 at 30kV air and 30kV contact discharge and those of flammability class UL94 V-0. The whisker test is carried out based on JEDEC JESD201A in accordance with Table 4a of Classes 1 and 2.

Various types with positive breakdown voltages (VBR) between 17.6V and 23.4V are offered depending on the required maximum gate voltage. The negative breakdown voltage is 7.15V in each case.