Junction Temperature

The average chip-junction temperature, TJ, in °C can be obtained from the following:

  1. 1.TJ = TA + (PD x θJA)
  2. 2.TJ = TA + (PD x (θHEATSINK + θJC))


From the first equation, the user can derive the estimated lifetime of the chip and decide if a cooling device is necessary or not. If a cooling device is to be fitted on the chip, the second equation should be used to compute the resulting average chip-junction temperature TJ in °C.