Computer-controlled uninterruptable power supply

Abstract

A computer-controlled, uninterruptable power supply system is disclosed. The system selectively operates from more than one input source of power, e.g., an AC input, an external DC input and internal batteries. The system is of the type which utilizes one or more switch mode converters and is especially suited for use in computer systems. The system monitors a number of functions under computer control and reacts automatically to the monitored functions to follow a programmed course of action. During start up, the system monitors prescribed functions and prevents power turn-on upon detection of prescribed faults. The system may communicate with a host computer, provide data thereto, and receive down-loaded parameters therefrom. Such down-loaded parameters may be used by the system to control operation of the system. The system determines the condition of internal batteries so that when operating from the batteries, the system is cognizant of how long it or a host may continue operating, and then reacts accordingly. The system includes at least one fan and a number of sensors which sense temperature at a number of locations in the system, and is capable of controlling fan operation and locating faults based on sensed parameters. The system comprises a watchdog circuit to monitor computer operation. The watchdog circuit and the computer periodically self test operation of the watch dog circuit. The system determines current drain by means of a current sense resistance which is a trace on a circuit board, and the system itself calibrates the sense resistance.