CYUSB2304-68LTXI: Powering ON/OFF sequence of VBUS_US and VBUS_DS (KA-03323)
VBUS_US (pin 17) and VBUS_DS (pin 18) can be powered anytime even if both 3.3 V and 1.2 V power domains are not powered. There is no specific power-up sequencing required for VBUS_US.
Note: The pin voltage changes take effect in Apple Charging sequence only when the Hub reads the status of the pin. The Hub reads the status at bootup and after a power cycling/reset. https://www.cypress.com/documentation/application-notes/an92554-implementing-battery-charging-featur... See AN92554 Implementing Battery Charging Features Using HX3 for details on the Apple Charging sequence. More https://community.infineon.com/t5/Knowledge-Base-Articles/HX3-FAQs-KBA224063/ta-p/260248 here.