Patent ID: 7099462
Filing Date: 2006-08-29
Classification: H04M

Abstract:
1. A switching device for selectively applying one of two different voltage supplies to a common node, a first of said voltage supplies being coupled to said common node by a first switch and a second of said voltage supplies being coupled to said common node by a second switch, said switching device comprising: (a) a feedback network comprising a high-pass filter that filters a signal at said common node and that outputs said signal having been high-pass filtered as a feedback signal; (b) a timing controller coupled to at least one of said first and second voltage supplies, that determines when to switch between said first and second voltage supplies; (c) a ring switch controller that applies a first control signal to said first switch for selectively enabling and disabling said first switch in response to said timing controller and said feedback signal; and (d) a battery switch controller that applies a second control signal to said second switch for selective enabling and disabling said second switch in response to said timing controller and said feedback signal.