A temperature calibration device uses Peltier cells for heating and cooling. The Peltier cells are driven by a power controller that gradually changes the power applied to the Peltier cells from a starting power to a target power. However, during this transition, the power controller holds the power applied to the Peltier cells constant for a period to minimize the stress on the Peltier cells. This period of constant period may last until the temperature of an object reaches a predetermined temperature, or it may have a fixed or variable duration, which may be based on the difference between the starting power and the target power. By changing the power applied to the Peltier cells in this manner, the useful life of the Peltier cells is preserved.