The transistor behavior in a circuit with a shorted load

If a transistor is working in a circuit with a shorted load, two different cases have to be distinguished. Case 1 is when a transistor is switched on in a circuit with a shorted load. This case was treated in the past. A second case that has to be considered is when a short occurs during the on state of the transistor. The results of one-dimensional simulations for case 2 show that collector-emitter voltage at the transistor depends strongly on the current density, with the maximum field occurring at the n/sup -/n/sup +/ junction of the collector. During the first critical time interval, the metallurgical p-n junction has no influence. The high current densities occurring during the short can produce electric fields higher than 10/sup 5/ V/cm. These current-induced high electric fields result in a current runaway causing, finally, a thermal destruction of the transistor, even at voltages much lower than the specified stationary values. The current rise has to be limited by a small inductance allowing the transistor to consume voltage without exceeding critical field values.<
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