Abstract: An apparatus for powering an electrical circuit includes a first voltage input configured to receive power from a first voltage source, a second voltage input configured to receive power from a second voltage source, wherein the second voltage source has a lower voltage than the first voltage source, a voltage regulator connected to the first voltage input, and a voltage output configured to switchably receive power from the first voltage input through the voltage regulator or from the second voltage input.

Abstract: An apparatus for powering an electrical circuit includes a first voltage input configured to receive power from a first voltage source, a second voltage input configured to receive power from a second voltage source, wherein the second voltage source has a lower voltage than the first voltage source, a voltage regulator connected to the first voltage input, and a voltage output configured to switchably receive power from the first voltage input through the voltage regulator or from the second voltage input.

Abstract: A loss-of-clock (LOC) detector circuit detects a clock failure substantially within a specified number of clock periods and generates a loss-of-clock signal. The LOC detector includes a frequency-to-current converter which generates a charging current substantially proportional to a frequency of an input clock. A capacitor accepts the charging current and provides a terminal voltage that changes in response to the charging current. An edge detector receives the input clock signal as an input and produces an output pulse on an edge of the input clock signal. A switch is coupled to the capacitor such that the capacitor is discharged to a reference potential when the switch is closed. The switch is controlled by the edge detector to close when the edge detector output pulse is asserted. A comparator generates a loss-of-clock signal when the voltage on the capacitor passes a trip voltage of the comparator.

Abstract: A circuit includes a first capacitor having a first terminal coupled to a first node having a first potential during a first time interval, and is coupled to a second node at a reference voltage during a second time interval. The first capacitor has a second terminal coupled to a third node having a common potential during the first time interval, and to an integrator during the second time interval. The first capacitor receives a first charge component from the second node that is dependent on the first potential during the second time interval. A second capacitor has a first terminal that is coupled to a fourth node having a second potential during the first time interval. The common potential is substantially midway between the first and second potentials. The second capacitor provides a second charge component that cancels the first charge component during the second interval.