drop in bus voltage

[azot_0]

Hi,

is it possible to disable detection of low bus voltage in FX2/CY7C68013A?.  bus voltage ,VBUS , could go low due to limited non-damaging current spikes causing FX2 to react.

[MallikaK_22]

Hi,

Could you please let us know if you mean disabling the sensing of VBUS by the FX2LP firmware or disabling the external monitoring of VBUS?

[azot_0]

Would like to know both methods. By the firmware and external monitoring as like to know by the firmware method for sure.  Does by the firmware method stops the re-enumeration in case of low vbus?. Any side effects?.  

[Meghavi · Accepted solution]

Hi,

A USB-IF specification requirement is to never drive the USB pins when they are not connected to the VBUS. In order to meet this spec requirement, it is always recommended to use a VBUS monitor circuit in self-powered devices. Please refer this KBA: https://community.infineon.com/t5/Knowledge-Base-Articles/VBUS-Pin-of-USB-Connector/ta-p/259031. 

For more details on how VBUS can be monitored in firmware for self-powered and bus-powered device, please refer to section 2.1 of AN15456_Guide_to_a_Successful_EZ-USB_FX2LP_Hardware_Design 

Best Regards