Unitrode Corporation

Other

Mark G Jordan

Robert A Mammano

John A O'Connor

Thomas P Hack

James R Garrett

Francis H Terry

A circuit breaker IC adapted for controlling an external NMOS switch coupled between a supply voltage and a load referenced to ground, with the circuit breaker being isolated from ground. With this arrangement, the voltage across the circuit breaker is limited, thereby permitting use of a low voltage integrated circuit fabrication process. The circuit breaker includes a sensor for sensing load current through the switch and providing an output signal indicative of the load current, a charge pump providing a supply voltage and an amplifier responsive to the sensor output signal and to the charge pump supply voltage for providing a drive signal to control the switch.

Floating positive circuit breaker

A multiplexing power converter for use with a single inductor for providing multiple power outputs is disclosed. The multiplexing power converter includes first switching means for providing a first low resistance path for current to flow from a power source through an inductor so as to energize the inductor, and at least one second switching means for providing at least one second low resistance path for current to flow from the inductor so as to deenergize the inductor and provide an output current. Only one low resistance current path is provided at any one time.

Multiplexing power converter

A low capacitance impedance emulator suitable for active conductor termination. The impedance emulator includes an emulating FET and a control circuit coupled to the gate of the emulating FET for maintaining the FET in a linear region of operation. The control circuit includes a control FET, an impedance setting resistor, and an amplifier. The control FET is driven in a closed-loop fashion so that the impedance of the control FET has a known relationship with respect to that of the resistor. The output of the amplifier controls the conduction of both the emulating and control FETs so that the emulating FET provides an impedance proportional to that of the control FET and thus, related to the impedance of the resistor. A disconnect feature is provided, whereby the impedance emulator is responsive to a disconnect signal for disconnecting the impedance provided by the emulating FET. The impedance provided by the emulating FET is selectable by adjusting the impedance setting resistor or, in one embodiment, the impedance is selectable in response to an impedance selection signal which causes one of a plurality of FETs to operate as the emulating FET. An NMOS FET having features providing enhanced ESD performance is also provided.

Impedance emulator

A solid state circuit breaker for use in electronic devices which may be connected to an active computer bus. In one embodiment the solid state circuit breaker includes a digital to analog converter by way of which digital control signals are used to set the value at which the circuit breaker determines that a fault condition exists. Fault time is measured from when the fault condition is detected, and when the fault time exceeds a predetermined value, the circuit breaker opens, thereby preventing current flow through the circuit breaker for a second predetermined amount of time. Once this second predetermined amount of time elapses, the circuit breaker again permits current flow, and if a fault condition is determined to continue to exist, the cycle is repeated. The circuit breaker also includes a current limiting portion which restricts current flow to a maximum permissible value should the current flowing through the circuit breaker attempt to exceed this maximum permissible value. A reverse voltage comparator circuit interrupts current flow through the circuit breaker if the voltage at the output terminal of the circuit breaker exceeds the voltage at the input terminal of the circuit breaker.

Electronic circuit breaker

A controllable bus terminator for providing a switchable termination on a bus having a plurality of conductors, wherein the controllable bus terminator includes a voltage regulator, a plurality of termination networks, each having a first terminal and a second terminal wherein the second terminal of each of the termination networks provides an output terminal of the bus terminator. The bus terminator further includes a plurality of electrically controllable switches, each of the switches having a first port coupled to the voltage regulator and a second port coupled to the first terminal of a corresponding one of the termination networks wherein each of the switches couples the corresponding termination network to the voltage regulator when the corresponding switch is in a first state and wherein each of the switches disconnects the corresponding termination network from the voltage regulator when the corresponding switch is in a second state.

Controllable bus terminator

A bus terminator, for a computer bus, which is capable of providing maximum allowable current to the bus, voltage clamping of the bus and steady state power reduction when the bus is in the positive steady state.

Current source bus terminator with voltage clamping and steady state

An active negation emulator circuit for improving the noise margin of signals carried by a signal interface bus. The circuit includes a sensor for sensing the voltage on the bus and a variable current source for supplying a current to the bus when the voltage level thereon is greater than a predetermined value. More particularly, when the voltage level on the bus is indicative of the signal carried thereby being in a logic high state, a current is supplied to raise the voltage level to the desired logic high voltage level. A combination circuit is also provided including an active negation emulator circuit, a resistive terminator, and switch means for selectively coupling the active negation emulator to the signal interface bus, coupling the resistive terminator to the signal interface bus, or decoupling both the emulator and the terminator from the bus, in accordance with the location of the bus to which the combination circuit is coupled.

Active negation emulator

A controllable bus terminator, for providing a switchable termination on a bus having a plurality of conductors, wherein the controllable bus terminator includes a voltage regulator, a plurality of resistive networks each of the resistive networks having a first terminal and a second terminal wherein the second terminal of each of the resistive networks provides an output terminal of the bus terminator. The bus terminator further includes a plurality of electrically controllable switches, each of the switches having a first port coupled to the voltage regulator and a second port coupled to the first terminal of a corresponding one of the resistive networks wherein each of the switches couple the corresponding resistive network to the voltage regulator when the corresponding switch is in a first state and wherein each of the switches disconnect the corresponding resistive network from the voltage regulator when the corresponding switch is in a second state.

Controllable bus terminator with voltage regulation

A silicon controlled rectifier device including an SCR portion controlled by an input voltage signal to a voltage comparator and having a latching circuit to permit the SCR portion to remain in the conducting state once switched even in the absence of the input voltage signal. Such a device is especially useful when a narrow input voltage signal is used to switch the SC portion into its conducting state.

High speed, low forward voltage drop, SCR

A load current sharing circuit is disclosed that allows multiple independent power modules, either switching or linear, to be connected in a parallel configuration such that each module delivers only its proportionate share of the load current. Each module measures the common output voltage, compares that voltage to an internal reference voltage signal, and generates an error voltage signal to be used as feedback for regulating its output voltage. The internal reference voltage signal is a function of the extent to which the current within each module differs from the current of the module with the highest current. That module functions as the master, and all the other modules act as slaves. Each slave increases its share of the load current so as to asymptotically approach the load current of the master to within a preset offset voltage, while the load current of the master decreases.

Growing community of inventors

Goffstown, NH, United States of America

Mark G Jordan