Part Number:ULN2803A
For ULN2803ADW in Section 6.4 Thermal Information, RθJA Junction-to-ambient thermal resistance 66.4 °C/W is given. Other parameters are given as well.
I am confused because this Section references to Thermal Metrics, SPRA953C; which says, "Tj = Ta + RθJA*Power is often a misapplication of the RθJA thermal parameter because RθJA is a variable function of not just the package, but of many other system level characteristics such as the design and layout of the printed circuit board (PCB) on which the part is mounted.
Question, why make this complicated? Is your application based on JEDEC to give you 66.4 °C/W. If so, which one High L or Low?
How exactly did you arrive at 66.4?
In other words. Please show me step by step how to calculate worst case Tj at say 55C.