Hi all. I'm putting together a fairly simple project, imstalling a bluetooth amp in the shell of an old boonbox to power the speakers. For power delivery, I intend to use a lithium ion powerbank capable of supplying 20v via USB-C and a USB PD spoofer.

The only problem is, the powerbank also charges through the USB-C port, so as-is it would have to be unplugged to charge, and I want it to be internal.

Since all the battery charging circuitry is already taken care of, I'd like to design a simple circuit that can redirect voltage towards the powerbank when a power source is connected, and to the amp when disconnected. It might be the sort of thing that's been created before, but if not, I'm thinking I just need a MOSFET and some USB-C connectors on a PCB, and run the voltage rails through the MOSFET. Does that sound reasonable?

 

Why not use a single pole double throw switch - power on / charge?

 

Why not use a single pole double throw switch - power on / charge?

I was hoping for it to be automatic, so that there was no possibility of error - is there a USB-c mechanical switch like that?

 

I was hoping for it to be automatic, so that there was no possibility of error - is there a USB-c mechanical switch like that?

Not that I know of. If you switch the battery+ to either the charger or the supply module, how could you get an error?

 

That's a good point! I'd still rather it was automatic if it's not a lot more work though

 

That's a good point! I'd still rather it was automatic if it's not a lot more work though

Are you not putting a power switch on your device? The OFF position is then for charging. It's pointless to add active circuitry that will switch the battery over to the charger when the power is turned off. It adds unnecessarry complication and more possibility of electronic failure.

 

Are you not putting a power switch on your device? The OFF position is then for charging. It's pointless to add active circuitry that will switch the battery over to the charger when the power is turned off. It adds unnecessarry complication and more possibility of electronic failure.

The Bluetooth amp itself contains the on/off circuitry, so adding another power switch outside of that just means I'll have to flip two switches to power it on and one of them to enable charging.

Can I please ask, ignoring specifics, if I really wanted for whatever reason to make a PCB that switches current in the way I described, could it be done with a MOSFET?

 

Can I please ask, ignoring specifics, if I really wanted for whatever reason to make a PCB that switches current in the way I described, could it be done with a MOSFET?

Yes, as long as you have a high enough voltage available to switch the gate of a MOSFET.