Question

The total thermal resistance of a power transistor and heat sink is 20°C/W. The ambient temperature is 25°C and (TJ)MAX=200°C. If VCE=4V, find the maximum collector current that the transistor can carry without destruction.

(a) 3.67A

(b) 7.56A

(c) 2.19A

(d) 4.16A

I have been asked this question by my college professor while I was bunking the class.

Asked question is from Thermal Stability in chapter Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

Answer 1

The correct option is (c) 2.19A

The explanation: PD =(TJ-TA)/ H

=200-25/20=8.75W.

Now, VCEIC  = 8.75/4=2.19A.