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Need theta_JC for PBSS5540Z BJT

Question asked by Carl Cygan on Apr 25, 2017
Latest reply on Apr 27, 2017 by Tomas Vaverka



I am evaluating the thermal performance of the PBSS5540Z BJT (bipolar junction transistor) and am measuring the case temperature using a Therma-Bridge (manufactured by IMS) to guarantee thermal conductivity between a J-type thermocouple and the PBSS5540Z collector case (the Therma-Bridge also guarantees electrical isolation).  I need to accurately calculate the junction temperature of this part.  Page 4 of 10 of the attached datasheet shows the junction to ambient thermal resistance (Rth_JA).  To calculate an accurate junction temperature, I need to know the junction to case thermal resistance (Rth_JC), since case temperature was measured and Rth_JA = Rth_JC + Rth_CA (thermal resistance from case ambient).


What is the thermal resistance from junction to case (Rth_JC) on this part? I have already contacted Nexperia 2 weeks ago and posted a similar technical support ticket on their website, but no one has responded yet and I need this information ASAP.


Thank you,


Carl Cygan