Selection of SCR for low duty cycle narrow pulse applications

Abstract

The paper describes the optimum selection of low frequency phase control type SCR for low duty cycle narrow pulse current applications. Four different design criteria have been reviewed and examples are illustrated with a particular type of SCR. It is shown that the design on the basis of information from the specification sheet gives lowest magnitude of peak currents. On the other hand, experimentally screening samples on the basis of low energy dissipation per pulse and consideration of thermal impedance on the basis of uniform chip dissipation gives the most optimistic result. For some critical applications, where coat and size of SCRs are to be minimum without, of course, the sacrifice of reliability, the experimental screening technique is recommended. Modern automated test procedure using microprocessor can be conveniently employed for this purpose.