Re: Power on Reset
Another simple,cheap and used Power on Reset chip is the Mitsubishi M51953.
The output of a Power on Reset chip goes high when the voltage at its input
reaches a specified value. For example, in the case of the M51953 the output goes high when its input reaches 4.25V (supposing to supply the chip whit 5V)
The time that the output is low before going to high level is set by an external capacitor.
On the opposite side, the output goes low when you turn off the supply and the voltage goes under the 4,25V.
So, the main function of a Power on Reset chip is well described by Borber post.
Another application, but during power off, is to sense when the voltage supply
is turned off. You can use this function, for example, to put audio amplifier in mute state when you turn off the power supply. In this case you can avoid "bump" noise on the speaker system.
Regards