Hi all, I have designed a simple circuit. It consists of a normal voltage regulator parallel with a PNP bipolar to provide high output current.

The problem is that the bipolar is very hot.

I tried to measure the voltage across the emitter-base junction, it is only about 0.3V. The VEC is 7V. The input current Ie is about 0.5A.

My questions:

1). Since the Veb is only 0.3V, is the Bipolar turned on or not?

2). what is the operating region?

3). is the overheating assocated with the Vbe=0.3??

thanks a million

 

The data sheet on the transistor will answer the operating condition questions. Can you post up a schematic so we can see what the circuit looks like?