Following parameters are given for the above circuit:
R1=8.2 kΩ, R2=5.6kΩ, RE=2.7kΩ, VEB=Uj=0.7V, Vcc=10V, β=200
The question asks the maximum load resistance RL for the transistor in active mode.
I solve the question in the following way:
The maximum load resistance RL for the transistor in active mode means to me the transistor is approaching to saturation at that point.
So for that point, I take Vce=0 and set Vy=Vx+0.7V.
Vy=Vcc*R2/(R1+R2) + 0.7V
Vy=10*(5.6/13.8) + 0.7V = 4.76V
Now since Vce=0V, and Ie=(Vcc-Vy)/Re = 1.94mA
Ic = Ie approximately so
RL = Vy/Ic = 4.76V/1.94mA = 2.45kΩ
So I calculate the maximum RL in active region as 2.45kΩ, whereas the answer is 2.1kΩ.
Is my calculation wrong?