I was thinking about designing an expansion card that would use the USB-C PD function and convert normal charging jack adapters to USB-C. Do you think that’s a good idea?
I think this would be pretty cool, @Kieran_Levin mentioned the laptop has a buck-boost charger built in, maybe he can chime in if we can go around the pd protocol and just put voltage on the + and - pins.
If the converter is built-in, that would make my job a lot easier. I thought the expantion card ports are standard USB-C ports.
They are but in order to be able to charge from a wide range of chargers (including standard 5v) they seem to have a more flexible charging solution internally.
Are the motherboard schematics public too?
I’d like to take a look at it to decide what I need in my design.
@GameFan you would need to comply with the PD protocol and advertise the correct power to the device, and also support 5Vsafe to start negotiation of a PD contract.
You cannot just apply power to the type-c input as the laptop needs to know the charger power to prevent overloading the charger as we control the power envelope of the system based on the negotiated power contract.
I am a lot more excited about PD-Legacy charger adapters so I can continue to use my old laptops and only need type-c chargers :D.
I assume there’s not a single chip solution to the PD protocol? The plan was that I’d have a boost/buck converter at the input to convert any voltage to 5V and connect it either directly or through a controller/manager chip and maybe have multiple input jack sizes to accomodate as many types of chargers as possible. Or if I decide I want to charge with more power than have the controller charge at 20V or something.
Sorry if I’m saying nonsense, I have never designed a USB-C circuit, let alone with PD functionality.
I would suggest learn about all the USB-C protocols before designing anything, my first expansion card did not even have CC resistors placed. Heat output and clearance will be your issue.