Abstract: A computer-controlled, uninterruptible power supply system is disclosed. The system selectively operates from more than one input source of power, e.g. an AC line input, an external DC input and internal batteries. The system is of the type which utilizes one or more switch mode converters and is well suited for use in computer systems. The switch mode regulator has a PWM clock signal and provides a PWM drive signal. The PWM clock signal frequency is substantially greater than the PWM drive signal frequency. Transferring between the DC power sources is done in a manner substantially transparent to the regulator and the load, generally as follows. A signal indicating a transfer to a selected one of the DC power sources is gated in response to the PWM clock signal to form a first logic signal that is synchronized to the PWM clock signal. The first logic signal is gated in response to the PWM drive signal so as to form a second logic signal that is further synchronized to the PWM drive signal.

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.

Abstract: A multiplexer samples multiple analog waveform signals to provide a sequence of input signals to an active low-pass filter. The bandwidth of the filter is determined by an input RC network having series resistance and shunt capacitance elements. As the multiplexer switches state to sample a different analog signal, the resistance elements of the filter are temporarily shorted to allow the filter input signal to rapidly charge or discharge the shunt capacitance element to a steady state voltage in response to any change in input signal voltage. The resistance elements are then unshorted to permit normal low-pass filter operation. Switch means are also provided to selectively disconnect the shunt capacitance element from the network when the resistance elements are shunted, thereby selectively widening the bandwidth of the filter to pass higher frequency input signals.

Abstract: A supply voltage driver for one or more monolithic differential amplifiers sharing common power supplies comprises an additional monolithic differential amplifier operated as a voltage follower suspended between a current source and a current sink. Reference Zener diodes are coupled between the voltage follower output and the power supply terminals of the differential amplifiers to establish operating voltages which track an input signal. Additional current-boosting transistors are provided to provide fast slew rate during signal transitions. Overdrive circuitry is provided to limit the maximum and minimum signal levels.

Abstract: A high performance, wideband instrumentation amplifier includes a main differential amplifier channel which receives an input signal having both differential and common-mode signal components, and a compensation amplifier channel which effectively removes the common mode signal component.