Table of Contents
What is primary breakdown in BJT?
BV is the collector base breakdown voltage when the emitter is open circuited. The primary breakdown shown takes place because of avalanche breakdown of collector base junction. Large power dissipation normally leads to primary breakdown. The second breakdown shown is due to localized thermal runaway.
What is the second breakdown in power BJT how is it avoided?
Once current filaments are formed localized “thermal runaway” quickly takes the junction temperature beyond the safe limit & the device is destroyed. Secondary breakdown can be avoided by using power transistor in safe operating area.
What is breakdown voltage in BJT?
The breakdown voltage at room temperature in the EB junction of the n-p-n BJT is around 6.3 V, both the breakdown mechanisms contribute to the EB breakdown characteristics.
What is Fbsoa of power BJT?
5 Safe Operating Area of a BJT. There are two such areas: the first is the forward bias safe operating area (FBSOA), which is shown in Fig. 10.10(a) and the second is the reverse bias safe operating area (RBSOA), which is in Fig. 10.10(b).
What is secondary breakdown and where it occurs?
Secondary breakdown is a failure mode in bipolar transistors in which negative resistance (current concentration) occurs under high-voltage and high-current conditions. Current concentration causes local heating, resulting in a small hotspot.
Why secondary breakdown does not take place in the IGBT?
Why secondary breakdown does not take place in the IGBT? The resistance temperature co – efficient of the IGBT is flat therefore it has no effect of temperature variation. The resistance of the IGBT remains constant and secondary breakdown does not take place due to above reason.
What is secondary breakdown?
How do you calculate breakdown voltage of a transistor?
Measuring breakdown voltage is done by applying an increasing reverse voltage to the device until a certain test current is reached that indicates that the device is in breakdown.
What is the second breakdown?
Secondary breakdown is a failure mode in bipolar power transistors. In a power transistor with a large junction area, under certain conditions of current and voltage, the current concentrates in a small spot of the base-emitter junction. This causes local heating, progressing into a short between collector and emitter.
What is SOA of IGBT?
The safe operating area (SOA) is defined as the current and voltage conditions over which an IGBT can be expected to operate without self-damage or degradation. In practice, it is necessary not only to use an IGBT within the safe operating area but also to derate its area for temperature.