A New Class of Solid State Isolators Enhances the Reliability of Solid State Relays

Abstract:
Solid state isolators (SSIs) transmit signal and energy over an isolation barrier for driving the gates of power transistors. This is very convenient as it makes the external output-side voltage supply obsolete. However, the vast majority of SSIs today use optical isolation and only a tiny amount of energy can be transferred. It allows neither the fast turn-on of transistors nor provides added integrated circuits for the protection of power transistors. This paper introduces a new generation of SSIs that can turn power transistors on and off much faster and provide protection against thermal and current overloads. The new SSIs target much higher levels of reliability in solid state relays (SSRs). This paper also explains dynamic Miller clamping, fast turn-on and turn-off, overcurrent and overtemperature protection, and provides measurements to prove the performance of the new SSIs.