Will the STUSB4500 assert (pull low) the ATTACH pin if it is connected to a USB 2.0 port? For example in the case a USB 2.0-A to USB-C cable is used where there is no host USB PD communication on the CC pins and only 5V appears on VBUS.

transistorboy32 · ‎2020-08-22

Also, will the VBUS_EN_SNK pin get asserted (pulled low) in this case, allowing the power path to enable 5V from the USB 2.0 cable to power the device?

Benoit FORET · ‎2020-08-26

Hello,

yes. STUSB4500 connects to any USB-C source advertising properly as a DFP, whatever it support USB PD or only USB-C (5V only). In case a USB2.0 STD-A to C cable is used, it is recognised as a USB-C source with USB Default current capability (in case of USB 2.0, 500mA). Therefore, ATTACH pin is asserted. Concerning VBUS_EN_SNK pin, behaviour can be configured thanks to POWER_ONLY_ABOVE_5V option. By default, STUSB4500 powers the device, but for applications not supporting default 5V, it is possible to prevent the switch from closing for those cases when device is not attached to a PD compliant SOURCE (like USB2 STD-A port for instance).

Rgds

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Benoit FORET · ‎2020-08-26

Hello,

yes. STUSB4500 connects to any USB-C source advertising properly as a DFP, whatever it support USB PD or only USB-C (5V only). In case a USB2.0 STD-A to C cable is used, it is recognised as a USB-C source with USB Default current capability (in case of USB 2.0, 500mA). Therefore, ATTACH pin is asserted. Concerning VBUS_EN_SNK pin, behaviour can be configured thanks to POWER_ONLY_ABOVE_5V option. By default, STUSB4500 powers the device, but for applications not supporting default 5V, it is possible to prevent the switch from closing for those cases when device is not attached to a PD compliant SOURCE (like USB2 STD-A port for instance).

Rgds