Patent ID: 6815655
Filing Date: 2004-11-09
Classification: H01L,H04N

Abstract:
A circuit, comprising:a first input terminal coupleable to a first voltage source; a second input terminal coupleable to a second voltage source; a first output terminal coupleable to a photodetector unit; a second output terminal coupleable to the photodetector unit a capacitor coupled to the first output terminal; a first switch coupled to the first input terminal and to the first output terminal, wherein the first switch to open during a power down sequence; a second switch coupled to the second input terminal and the second output terminal; a third switch coupled to the output terminal and a supply rail; and a threshold detector having an input lead coupled to the first output terminal and an output lead coupled to the second and third switches, wherein the threshold detector to cause second and third switches to open and close, respectively, during the power down sequence as a function of the voltage at the first output terminal.