I want a circuit that switches from ACtoDC ...

[mabauti]

power supply to battery powered when the ACtoDC power supply goes below 4 volts

The circuit has 5V for nominal supply, both ACtoDC supply & battery supply

any ideas?

 

[zzoorroo]

hi
there is a pdf file attach hear will help you

 

[mabauti]

I'm sorry. I'll say it in a different manner :

I want a circuit that if detects an AC failure switches to battery powered; and if the AC line is OK then return to AC powering.

 

[Gundam001]

A much clearer this time. The circuit is like a emergency light that when the AC power is OFF, the battery will the one to supply and vice versa. You just need a 5V supply..

Just one question is the battery rechargable?

 

[mabauti]

Just one question is the battery rechargable?

let say that it can be either normal or rechargeable

 

[Gundam001]

See attached...

Hope this can solve your problem.. Its just a simple reference design..

As you can see the output is coupled to N and P Channel FET, this are just fast switching MOSFET that will switch between supplies. If theres a Power, the output voltage will came from the LM7805 which will enable the N-channel FET to produced the desire output, and when theres a no power the P-channel FET will the one to be enable to produce the desired output..

As you can see the battery charger is very simple, you can couple a battery charger circuit to enchance the charging to the battery..

Enjoy..

 

[mabauti]

Thanks a lot Gundam001 , I'll try that =)

 

[Gundam001]

Its my pleasure, if there still a question just feel free to ask...