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USB type C power delivery

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gaminn:
Hi,
I'm designing an USB 2.0 full speed device (downstream port) with USB type C. The device will be connected to an upstream port of a tablet/phone.

There will be 2 power modes of the device:

1) No external power supply connected to the device. Then, the tablet/phone must provide 5 V on USB bus.
2) There is an external power supply connected to the device. Then the device will provide 5 V on the bus (and the tablet/phone can charge itself).

The device should be able to request switch between 1) and 2) or 2) and 1) at any time. The device doesn't have any battery. It is a device with USB type C connector to connect to tablet/phone and jack/second USB type C connector where external power supply will be connected.

I just started to read about USB type C. I know that CC pins on USB type C connectors take care of Power Delivery protocol which is probably what I want to use.

How is this going to be implemented? What chip should I buy to implement this feature on USB type C?

jismal:
I am also at a similar situation. The best method is to go with a USB type c PD controller like one from TPS65982. But for me cost was an issue. So I decided to violate the spec. Now my device can only be charged by a dumb usb cable. But it is able to power other usb downstream devices.
Anyway here is my implementation. (Yes it surely violate USB type C spec).

gaminn:
I can see those 50 - 100 pin devices mainly from TI that can do power delivery and I'm afraid of learning curve needed to understand them. So I was hoping there is a not so complicated way to achieve power role switch.

You have two equivalent USB type C ports in your design and based on CC pin state you either supply power to them or charge from them. That probably works (if you charge with dumb usb cable as you say as you always advertise that you are a source), but I also need to change power role during runtime.

My device is sink in default but when it detects it has external power adapter connected it should be able to request power role switch so the tablet becomes sink and the device becomes source. I wish it would be that simple as switching from pull down to pull up on CC pin and the switch magically happened :)

krho:
STM32G0 series provides CC pins and libraries for PD. However you'll need to protect the CC pins against the high voltage yourself. CC pins are close to VBUS so accidentally you can get up to 20V+ on them

gaminn:
Thank, great! Part for approx 1 USD that can probably do what I need.

I think also STUSB1602 controller would do the job.

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