Help with Uninterrupted Power Supply or UPS Circuit Diagram

[ikelectro]

Currently I'm doing a project with clock and security system in a single PCB. So the both need a uninterrupted power supply. I'm designing it for 5V DC power supply.

>> i have to supply power to this circuit if the current is gone(it is a regular in here). how can i design this kind of power supply for my project?
>> Can I have a simple circuit diagram for it?

 

[ikelectro]

View attachment 67872
i have found this one in the internet (in this **broken link removed** website).
is that ok for my project?
is there any way to make a better power supply than this?

 

[MikeMl]

It is rather a poor circuit. My dislike stems from the fact that it supplies unregulated voltage to float charge the battery. For a sealed lead-acid (SLA) battery, the float voltage is critical, too high and you will dry out the electrolyte and corrode the lead grid, too low, and the battery will be less than 90% charged causing the plates to sulphate.

A better design would utilize a battery charger chip like the PB137 to regulate the float charge voltage (13.70V for a six-cell battery). For a three-cell battery, the nominal float charge voltage should be 6.85V, and you could use a LM317 with a trim pot to set the float voltage.

I would start with a DC wall wart that puts out a nominal 6 to 9V. Use that to drive the float regulator. Diode-OR the 6V battery voltage with the wall-wart output as an input to a low-dropout regulator which creates the final 5V. Since you don't have much headroom between the battery and the low-dropout regulator, use a Schottky diode in that path.

 

[ikelectro]

It is rather a poor circuit. My dislike stems from the fact that it supplies unregulated voltage to float charge the battery. For a sealed lead-acid (SLA) battery, the float voltage is critical, too high and you will dry out the electrolyte and corrode the lead grid, too low, and the battery will be less than 90% charged causing the plates to sulphate.

A better design would utilize a battery charger chip like the PB137 to regulate the float charge voltage (13.70V for a six-cell battery). For a three-cell battery, the nominal float charge voltage should be 6.85V, and you could use a LM317 with a trim pot to set the float voltage.

I would start with a DC wall wart that puts out a nominal 6 to 9V. Use that to drive the float regulator. Diode-OR the 6V battery voltage with the wall-wart output as an input to a low-dropout regulator which creates the final 5V. Since you don't have much headroom between the battery and the low-dropout regulator, use a Schottky diode in that path.

Can I have the circuit please?

 

[MikeMl]

I thought I just gave it to you... You mean you want me to draw it up for you as well...