Electronic – USB plug in detection for charging port

detectionplugusbusb-host

Is there a way to detect if there is a USB cable physically inserted into a USB receptacle, even if it is just a cable (with nothing attached to it).

I am designing a USB charging port (short D+ and D- together styles) and would like to be able to disable the buck converter if there is nothing plugged into the USB receptacle (which will be >99% of the time).

I can't rely on the devices that will be drawing power from the receptacle to have any specific protocol in terms of negotiating charging current etc (i.e. can't use serially transmitted data from device X as a detection mechanism).

I think what I'm asking for is if there are USB-A receptacles with mechanical plug-in detection (along the lines of what is available for SIM cards and SD cards), or if there is a way of "sensing" a plug-in event transient (less inclined to go this route as it sounds pricey).

What say you?

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EDIT:
Found a receptacle with a "contact sense pin" feature that was referenced in another post:

Special USB Port With "Sensor" Contact

Best Answer

Yes, special USB receptacles have been defined within Power Delivery specifications. In version 2.0 an extra special contact was defined, for both USB 2.0 and USB 3.0/3.1 Type-A connectors. They were called "PD Standard A Connector", and there some protocol is defined as well.

In Power Delivery Rev 3.0 all Type-A and Type-B connectors are "depreciated", and the focus now is on Type-C connector.

Going forward, it might be challenging to find the original "PD Standard A Connector" with extra insertion detect contact. Wurth Electronics makes one for USB3, and Assmann, both are still available at Digi-Key.

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