SN74LVC125A: Thermal information

Hello Daniel,
The thermal values of this device are:
Maximum virtual operating junction temperature: T_j(max) = 150C (equal to Tstg(max), page 4 of the datasheet)
Ambient operating temperature range: T_A = -40°C to 125°C (pp. 1, 5, 6 of the datasheet)
Junction-to-Ambient thermal resistance (updated value): R_θJA = 128.8 °C/W
Junction-to-Case thermal resistance: R_θJC = 57.2 °C/W
Junction-to-Board thermal resistance: R_θJB = 70.7 °C/W
Junction to Top of Package characterization parameter: Ψ_JT = 9.5 °C/W
Junction to Board characterization parameter: Ψ_JB °C/W

This application report explains the definitions of each of the above specs if you need them:
www.ti.com/.../spra953c.pdf

A few years ago, TI changed the method by which we calculate our thermal specs to be much more accurate, accounting for changes in die size and material that had previously not been perfectly represented. That's why you see a change in the R_θJA I provided compared to that you found in the datasheet.