A Si transistor has a thermal ratings, Tmax = 150°C and

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A Si transistor has a thermal ratings, T_max = 150°C and θ = 0·7°C/W. The power which this transistor could dissipate if the case could be maintained at 50°C is—

1. 143 W
2. 59 W
3. 110 W
4. 85 W

Correct Option: A

Given, T_j(max) = 150°C, Q = 0·7°C/W
T_ambient = 50°C, P0 =?

From relation, P₀ =	T_{j (max)} – T_ambient
	Q

or P₀ =	150°C – 50°C	= 142·857 W
	0·7°C/W

or P0 ≈ 143 W
Hence alternative (A) is the correct choice.