Transistors

mstechca

New Member
When I buy BJT transistors from the store, the price label contains the following: amps, voltage, and polarity (NPN or PNP).

The transistors I buy are marked 100ma and 500ma.

Does this mean that the marked amp value is the minimum value required to turn it on?
 
No, that is the maximum current that it can handle. In other words, it is the maximum value of collector current for which the transistor operates safely. Beyond that it will go into "thermal run-away".
 
kinjalgp said:
No, that is the maximum current that it can handle. In other words, it is the maximum value of collector current for which the transistor operates safely. Beyond that it will go into "thermal run-away".

Just to be clear, this is not necessarily so. Thermal runaway is a power dissipation related problem. I can find an operating point such that the collector current is less than the maximum rated and still cause thermal runaway.
 
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