The maximum input voltage that can be applied to the L7912ACD2T-TR is 35V, but it's recommended to keep it below 25V for reliable operation.
To ensure stability, make sure to use a minimum output capacitance of 10uF, and keep the input and output capacitors close to the regulator. Also, avoid using long leads or wires that can cause oscillations.
The L7912ACD2T-TR is rated for operation up to 150°C, but its performance may degrade at high temperatures. Make sure to derate the output current and voltage according to the temperature derating curve in the datasheet.
Use a TVS (Transient Voltage Suppressor) diode or a varistor in parallel with the input capacitor to protect the regulator from voltage transients. Also, consider adding a fuse or a current limiter to prevent overcurrent conditions.
The L7912ACD2T-TR is not a low-dropout regulator, and it requires a minimum input-to-output voltage difference of 2.5V to maintain regulation. If you need a low-dropout regulator, consider using a different part like the LDO regulators from STMicroelectronics.