Thermal Resistance of High-Power Semiconductor Devices in the Pulsed Mode of Operation,

The article descusses the transient thermal resistance of various types of transistors and diodes acted upon by a power stage. It is found that for a realistic estimate of the p-n junction temperature of a semiconductor device operating in the pulsed mode, it is not enough to know only the thermal resistance of the device or only the thermal time constant. It is also necessary to know the transient thermal characteristic of the device vs. the pulse length and off-duty factor. The characteristics of the transient thermal resistance of the investigated transistors and diodes show that in the transient mode the power generated in the junctions may be double the permissible power.