VOLTAGE TRANSIENT PROTECTION CIRCUIT

摘要

A three terminal integrated low-resistant series switch circuit which buffers load electronics from extreme input voltage conditions. The circuit comprises a series pass transistor the conductivity of which is controlled by control circuitry in cooperation with feedback control. In response to the input exceeding a predetermined operating potential the series pass transistor is driven toward saturation and is maintained in this state by feedback whereby only that load current required by the load electronics is supplied for increased efficiency. The control circuitry is responsive to the signal at the input thereof exceeding a predetermined level for rendering the series pass transistor nonconducting to protect the load electronics from extreme voltage excursions. A feature of the circuit is that the epitaxial layer within which the control circuit is formed is operated at a lower voltage than that of the substrate.