Looking at the STCS1A datasheet I read:
Table 4. Thermal data Symbol Parameter DFN8 Power SO-8 Unit RthJC Thermal resistance junction-case 10 12 °C/W RthJA Thermal resistance junction-ambient 37.6(1) 45(2) °C/W 1. This value is referred to four-layer PCB, JEDEC standard test board. 2. With two sides, two planes PCB following EIA/JEDEC JESD51-7 standard.
About note 1: what is the standard here? The same as note 2 JESD51-7?
Here I read:
Summary of JEDEC Thermal, Multilayer Test-Board Specification JESD51-7 High Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages Material: FR-4Layers: two signals (front and backside) and two planes (internal) Finished thickness: 1.60 ±16mm Metal thickness: - Front and backside: 2oz copper (0.070mm finished thickness) - Two internal planes: 1oz. copper (0.035mm finished thickness) Dielectric layer thickness: 0.25mm to 0.50mm Board size: 76.20mm x 114.30mm ±0.25mm for packages less than 27mm on a side
If I understand correctly the two values of the thermal resistance are valid only if the IC is placed alone on a such a huge board of 76x114 mm? I hope I'm wrong...