VBUS Monitoring Pin for EZ-USB® TX2UL™ – KBA90066

Version: **

 

Question: The TX2UL™ CY7C68003 chip does not have a VBUS monitoring pin. Is there a way to monitor the VBUS?

 

Answer:

As noted, the TX2UL CY7C68003 chip does not have a dedicated VBUS monitoring pin. However, for a self-powered device design, you can use a GPIO of the processor chip to monitor the upstream VBUS. Code can be written to monitor the state of this pin and thus the VBUS. Once a "low" is detected on the pin being used to monitor the VBUS, the pull-up resistor on the D+ pin can be disabled. You can enable or disable the pull up by using the "termselect" bits in the function control register.