# Transistor collector current less than base current

What happens if the collector-emitter current is less than the base-emitter current? Do I need to increase the base resistor to lower the base current or is it okay to keep the transitor operating in this state?

The background is that I did connect a LED with a 2KOhm resistor to the collector side (5V) and I am using a 1kOhm resistor at the base side (3.3V, Arduino). Originally I used a 220Ohm resistor for the LED, but I just needed to reduce the LED brightness. I am not sure if I actually need to increase the base resistor value, just to keep the base current always lower than the collector-emitter current.

• It isn't a good practice to force too much base current in comparison with collector current. Usually it does nothing like in simple driving Leds but sometimes...it causes an ugly spikes.
– user208862
Nov 20, 2021 at 2:36
• You should not forget that under saturation condtions the current into the base is NOT identical with the base-emitter current. The B-C junction is forward biased and a remarkable portion of the base current goes into the collector.
– LvW
Nov 20, 2021 at 8:34
• @LvW: I dont understand this. Do you mean the current flows in the opposite direction, from base to collector? Nov 21, 2021 at 2:02
• When both pn junctions are forward biased there are two currents going through the base node: Ib=Ibe+Ibc. Does it not sound logical? That is the reason Kevin White wrote: The collector current can even be zero: Ic=Ice - Ibc (opposite directions).
– LvW
Nov 21, 2021 at 9:51