Patent ID: 7460966

Claim:
A method comprising: (a) operating a microcontroller in a nominal power mode, wherein the microcontroller comprises a digital circuit and an analog circuit, wherein in the nominal power mode both the digital circuit and the analog circuit are powered, wherein the analog circuit comprises a capacitor and a switch, the switch being coupled in series with the capacitor, the capacitor having a capacitance of at least one half picofarad, wherein a first voltage is present across the capacitor when the microcontroller is operating in the nominal power mode; (b) terminating microcontroller operation in the nominal power mode and beginning microcontroller operation in a low power mode, wherein said terminating and beginning comprises: (b1) making the switch substantially nonconductive such that the first voltage is stored on the capacitor; (b2) unpowering the analog circuit; and (b3) unpowering the digital circuit; (c) operating the microcontroller in the low power mode, wherein during the low power mode the switch is substantially nonconductive; and (d) terminating microcontroller operation in the low power mode and beginning microcontroller operation in the nominal power mode, wherein said terminating and beginning comprises: (d1) making the switch substantially conductive, wherein immediately before the switch is made substantially conductive a non-zero second voltage was present across the capacitor; (d2) powering the analog circuit; and (d3) powering the digital circuit.