In a fixed bias common emitter configuration, the collector saturation current is given as:

Concept:

When the transistor is operating in saturation, the current through the transistor is the maximum possible value. This current is called collector saturation current.

It is independent of the DC current gain of the transistor.

In saturation the BJT act as a closed switch hence V_CE is very low ( ≈ 0.2 V for si).

Analysis:

From the given circuit;

Using KVL equation the collector saturation current:

\(I_{Csat} = \frac{V_{CC}-V_{CE}}{R_{C}} \approx \frac{V_{CC}}{R_{C}}\,(As \,V_{CE}\,is \,very \,low)\)