using both adapter voltage and battery voltage

[hddn]

Hello everyone,

I have a PCB design that is powered by mains electricity via an adapter. When mains electricity ON, I want it to switch to li-ion battery mode and provide energy. When mains electricity OFF, the battery must not provide energy. At the same time, I want the battery to be charged from the circuit when not in use.
The battery will be embedded, it cannot be taken out and charged. How to split battery voltage and adaptor voltage? Which components should I use?

I can say that it works like computers battery system.
That is, if the system is working with the adapter, there must be no voltage coming from the battery to the system.
If there is no mains electiricty, the battery must be activated and the system must be operated. There should be no energy flowing to the adapter.
The battery should only be activated automatically when there is no mains electricity. I've attached a flowchart.

I didn't know how to do this.
If you have any information, I would like your help.

Thanks in advance.

 

[betwixt]

The simplest solution uses two components, a change-over relay and a diode across its coil. Power the relay coil from the mains adapter so it is active whenever mains is present. Use the relays switch contacts to divert the flow as required.

Brian.

 

[KlausST]

Hi,

does it make sense?
When mains is ON --> use battery, so ON, ON
When mains if OFF then don´t use battery ... so OFF, OFF
It somehow contridicts the other informations.

What does "charged from the circuit" mean? Where does the power come from? You mean: Charged from mains/adapter?
What does "circuit not in use" mean? How can one electrically determine whether the circuit is in use or not?

How to split battery voltage and adaptor voltage?

"Split" or "combine" or "select"?

Combine: via diodes, or an "idel diode circuit"
Select: Relays, transistors, MUX

Which components should I us

It mainly depends on: voltages, current, function, timing, efficiency....
but also on effort, cost, volume...

it could be: (simple)
12V --> diode --> DC/DC -> 5V
in parallel:
Battery -> diode --> DC/DC
and
12V --> charger --> battery

Klaus