I want to mount two transistors on one heat sink. Can some one inform me of the differences in calculation between that and one transistor.
The parameters are:
6W dissipation
no thermal resistance for the past
the heat sink thermal resistance is 2.5 deg C/W
junction temperature for either is 100 degrees C
thermal resistance for each transistor is 7 deg C/W
Ambient temperature is required
My working for one is
Ambient resistance = juc temp - (Therm res Hs+ therm res tras)* power dis
?= 100 - (7+2.5)* 8 = 24 degC

 

Is that 6W dissipation for one transistor (12W total ) or both transistors (3W each)?