The behavior of any semiconductor device depends on the temperature of its die. Hence, electrical parameters are given at a specified temperature. To sustain the performance of a component and to avoid failure or damage caused by overheating, the total power dissipation of the device has to be limited according to the maximum operating temperature. Vishay’s VO3526 is a three-dice DIP-16 power phototriac. In this application note, the device’s detailed thermal model is simulated and validated against experimental results, helping designers understand thermal energy transferring and assisting in power dissipation calculation and PCB layout.