Ideal backup power for PIC micro

[emavil]

hi folks!

Is there any method implementing a backup power system for PIC Micro? Just like the case of DS1302 RTC interfaced to PIC Micro (A real-time digital clock with calendar project). If you want to ensure that the clock/calendar info from DS1302 is up-to-date, then a simple 3v Lithium coin battery is adequate. Even for long-time power interruption.

Can we do the same approach with PIC Micro (only PIC Micro, the rest of the circuitry is off. A small battery, just enough to let PIC up and running for a long-period with or without power interruption?

[BrianT]

I am not sure what you are really looking for but I have many battery powered PIC projects that run for over 1 year on manganese alkaline batteries. I make sure all peripheral loads can be switched off by the PIC then I call the sleep function (must have WDT enabled for sleep to work). My projects do not need to use a 'wake on interrupt' but instead I have the PIC come out of sleep every 60 seconds and check for certain conditions to decide whether to run the code or go back to sleep.

I use mainly the PIC16F877A on 4 MnAlk batteries. These give 6.4 volts when fresh and I use no voltage regulator. Section 17.0 of the PIC16F877A data sheet gives a maximum Vdd 0f 7.5 volts so it all works within specs.

HTH
Brian

[emavil]

thats cool, can you share to me the schematic of your circuit? only the one that is powered by these batteries. I have a simple digital clock (HH:MM:SS) which i would like to run 24x7 with or without power from the mains supply. I'm using a standard wallwart adaptor as my power source. When mains supply is cut off, the next time i power on i have to set the time again.

[skimask]

thats cool, can you share to me the schematic of your circuit? only the one that is powered by these batteries. I have a simple digital clock (HH:MM:SS) which i would like to run 24x7 with or without power from the mains supply. I'm using a standard wallwart adaptor as my power source. When mains supply is cut off, the next time i power on i have to set the time again.

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