The recommended operating temperature range for the 1N4734A is -65°C to +175°C, although the datasheet only specifies the electrical characteristics at 25°C.
To ensure proper derating, consult the datasheet's power derating curve, which shows the maximum power dissipation vs. ambient temperature. For example, at 100°C, the maximum power dissipation is approximately 50% of the rated value at 25°C.
The typical dynamic impedance of the 1N4734A is around 10-20 ohms, although this value can vary depending on the operating conditions and frequency. This information is not explicitly stated in the datasheet.
While the 1N4734A can be used as a voltage regulator, it's not the most suitable choice due to its relatively high dynamic impedance and limited power handling capability. A dedicated voltage regulator IC would be a better option for most applications.
To calculate the power dissipation, use the formula P = (Vz * Iz) + (Vr * Ir), where Vz is the zener voltage, Iz is the zener current, Vr is the reverse voltage, and Ir is the reverse current. Consult the datasheet for the relevant values and consult a reliable electronics textbook for more information.