Abstract:
USB, despite of being of the most commonly used
serial bus protocol, has had posed many challenges for embedded systems community. Most common among these challenges include device detection and timeout failures, due to
the inconsistency between the USB (protocol) specifications and
eXtensible Host Controller Interface (xHCI) specifications. One
such limitation related to USB power discharge is very often
faced by USB engineers. To solve this problem, a two-resistor
model has been developed in past, which has been found to
have certain limitations and thus, does not accurately predict
the discharge profile of the USB power for most of the device.
So, in this paper we have presented an improved new model for
USB power discharge (VBUS) mechanism as a dual current based
model. With this model we improve the accuracy of discharge
profile and reduce the model vs silicon error up to 75%. We
claim that this representation of USB power discharge model is
much more accurate and can aid the device designers in their
calculations.
