Thermal resistance, Junction−to−Ambient (ϕ JA\$ϕ_{JA}\$) of NCP1117NCP1117 voltage regulator is 160 °C/W and thermal resistance of AMS1117AMS1117 voltage regulator is 90 °C/W. Remaining specifications are almost same for both regulators. Which of them is preferable? What
What is the role of thermal resistance while choosing a voltage-regulator?