New solid-state isolators enable superior pulse-current robustness in Si MOSFETs

Abstract:
Solid-state relays (SSR) that use silicon (Si) MOSFETs as switching elements have an extremely slow turn-on. Due to this, the MOSFETs require derating which is expensive. The cost factor lowers the scope of silicon MOSFET-based SSRs in applications with low current loads. High in-rush currents can still occur, for example, with resistive-capacitive loads while the steady-state current is low. In combination with slow gate charging, this is a threat for solid-state relay applications that can create high in-rush currents. This paper investigates the capability of the recently launched solid-state isolator (SSI) by Infineon Technologies that improves the gate-drive capability in combination with tailored MOSFETs. The relevant functions of the SSI including their effect on the turn-on performance is also covered in this paper. The methodology and results of the tests conducted using a high-current stress test circuit with resistive load under stress conditions far beyond the rated current are also discussed.