USB type C power delivery - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: August 20, 2019, 12:42:31 pm
content: 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?

author: jismal
author_rank: Contributor
timestamp: August 22, 2019, 07:14:43 am
content: 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).

author: gaminn
author_rank: Frequent Contributor
timestamp: August 22, 2019, 11:21:21 am
content: 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

author: krho
author_rank: Regular Contributor
timestamp: August 22, 2019, 05:01:37 pm
content: 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

author: gaminn
author_rank: Frequent Contributor
timestamp: August 22, 2019, 05:17:39 pm
content: Thank, great! Part for approx 1 USD that can probably do what I need.I think also STUSB1602 controller would do the job.

author: ddavidebor
author_rank: Super Contributor
timestamp: August 22, 2019, 05:58:59 pm
content: Just dropping in for a recommendation: if you need good and cheap usb-c connectors check the one from company Korean HROparts

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 22, 2019, 06:05:59 pm
content: Another one if you're looking for an easy to hand-solder USB-C connector: Hirose CX70M-24P1It's a mid-mount connector. Easy to hand-solder with just a soldering iron. Downside: may not be the easiest to route on PCB.

author: krho
author_rank: Regular Contributor
timestamp: August 24, 2019, 06:57:09 am
content: STUSB1602 won't work as its sink only controller.

author: gaminn
author_rank: Frequent Contributor
timestamp: August 24, 2019, 07:19:13 pm
content: In datasheet I can see that it can do sink, source and dual role.https://www.st.com/resource/en/datasheet/stusb1602.pdf

author: krho
author_rank: Regular Contributor
timestamp: August 25, 2019, 06:31:37 pm
content: Ah sorry. I mixed it with STUSB4500