# Output voltage vs output current

1. Nov 15, 2009

### ananthu

In the output charecteristics of a transistor in CE mode, according to the eqation
VCE = VCC - IC RC it comes as when VCE increases IC
decreases and vice versa. But it is only because of the reverse collector-emitter voltage, the charge carriers are attracted to the collector side from the emitter side. Hence when the collector-emitter voltage increases collector current should also proportionally increase until it reaches the saturation value. Then why do we have a completly contradictory result in the above equation? According to this equation when collector-emitter voltage is maximum the collector current becomes zero and when the collector-emitter voltage is zero, the collector current becomes maximum! I need a logical explanation for it. My question is when the the collector-emitter voltage is zero how the collector current could become maximum as they can not reach the collector side at all as the accleration given to them by the collector-emitter voltage will also be zero?

2. Nov 15, 2009

### vk6kro

The transistor does not have zero volts across it at saturation.
It always has a small voltage between collector and emitter.

I only has minimum voltage across it at that time because there is a series load resistor that drops most of the voltage reaching the transistor.

Last edited: Nov 15, 2009