Hmmm.... Well, the last posts about reset circuits put me in thought. From what I have seen most of you use some kind of reset/supervisory circuits instead of simple RC networks. I 've done a search in the forum for such chips and brown-out detectors, but I would like to ask: When do you have to use a reset/supervisory circuit? Is it always necessary?

For example, I would like to give you some details for my mp3 player project. I use the Cypress EZ-USB FX2 (128 pin version) uC. Cypress suggests only a simple RC network for the /RESET. In fact the FX2 development board (CY3681),that I own, has only an RC network with a 1N4148 diode added parallel to the resistor.

The PCB that I am designing will have on-board power supply. The player will be powered by NiMH AA batteries with the help of a MAX1626ESA step down DC/DC converter for the 5V devices (hard disk,lcd display) and a MAX8869EUE33 regulator for the 3.3V devices (all the other chips). Also the TEA1102T battery charger will be there (apart from the other features, it can detect low battery).

I also have to add that the FX2 uC doesn't have on-chip flash memory (I will use a PSD memory from ST) and doesn't implement a watchdog timer.

With all the above details given, what do you suggest me? And once again: Finally, is it always necessary to use reset/supervisory chips? Thanx in advance...

George