Kari,

(((Cristian, do you have examples about good and bad circuits? I must say that this sort of thing never crossed my mind, I thought I can just make a circuit for cutting power after all writing has been done.)))

1. If you are not concerned with the accidentally power down ( as I understand) there are not problems.
The problem is at power up as a wrong reset can disrupt the internal eeprom data.
So I advice you to use a special reset IC like MAX813L/707/708.
This is the “”good”” circuit.
The bad one is to use the classical RC (+diode) reset circuit as this leads, sometimes, to inaccurate triggers for reset an disrupting of the eeprom contents ( as I said I experienced this).

2. If you want to take in consideration also the power supply failures you must use a supervisory circuit like MAX691/693/800 with a battery or SuperCap for the preservation of the power during eeprom writing. Be aware to cut the auxiliary power after the writing process is accomplished (not necessary for a supercap of course).

If you thing the data sheets of the above ICs aren’t enough explanatory for you ask me details and I‘ll be glad to give you assistance.

Best regards,

Cristian Ceausescu