Part Number: TPS54331
Hi all:
I have followed application note SLV551 to develop a simple CC/CV battery charger, as it is explained in the application note.
My battery charger should have also the following features:
- 12 V input
- 11.1 V nominal voltaje battery
- A secondary external device is connected to that PCB. That external device has 9V-14 V input, and is turn on/off thruogh an external button
- The normal behaviour of the system should be:
- If no button is pressed and the battery charger is connected to the network, then the battery is charging
- If the buttom is pressed, and there is no external network connected, the external device turns on. it Will start up and work using the battery
- If the buttom is pressed, and there is external network connected, the external device turns on. Like a mobile phone turn on and charging the battery at the same time.The battery should charge, or at least not be discharged .
But one question comes to my mind, probably it is very simple, but I would like to have your opinion.
Regarding the circuit, The battery is connected between the output terminal and the sense resistor. It means that the negative terminal of the battery it is not connected to input GND, because the Rsns is beteen both places, so the battery negative terminal has some voltaje over GND (typically 0.8 V).
My first idea is just so simple as the battery will supply the power to the external load. But unfortunately the external device has a high power consuption, so if turn on the device and I am charging the battery at the same time, the battery will finally goes under the mínimum voltaje and the external device will turn off, even with external supply connected. This is a non conventional behaviour for a normal user.
So how could I solve that? any idea
best regards
