Abstract: A power supply for a television apparatus, comprises a first source of unregulated DO run voltage operable only in a run mode of operation and a second source of unregulated DO voltage operable in a standby mode and in the run mode of operation. A first regulator responsive to the first source unregulated DO run voltage produces a first regulated voltage. A second regulator responsive to the second source of unregulated DO voltage produces a second regulated voltage. First and second integrated circuits are energized respectively by the first and second regulated voltages. At least one of the integrated circuits has a signal output coupled to a signal input of the other of the integrated circuits. A controller is operable in the run mode and responsive to variations of one of the regulated voltages for adjusting the other of the regulated voltages to follow the variations. Each of the regulators may comprise a series pass transistor and a control transistor coupled to a base of the series pass transistor.

Abstract: A power converter for providing a selectable desired voltage has a converter circuit having an input port for receiving an input of a first voltage and an output port for providing an output of a second voltage. The converter circuit also has a keyway for receiving a key. The key, which is configured to be received by the keyway, contains an electrical component and has a body within which the electrical component is disposed. The output voltage of the converter is determined by the value of the component disposed within the body of the key such that the output voltage can be varied by replacing the key with another key having an electrical component of a different value.

Abstract: An integrated circuit bandgap voltage reference, in which the regulated voltage is equal to the sum of a first transistor's base-emitter voltage plus a voltage which is proportional to the difference between the base-emitter voltages of two transistors operating at different current densities, PLUS an additional voltage which is equal to the base-emitter drop of an additional transistor. The additional transistor is connected to an emitter resistor which ensures that variations in resistor values will cause the base-emitter drop of the additional transistor to vary oppositely to the base-emitter drop of the first transistor. The resulting voltage reference circuit has high stability and low power consumption.

Abstract: A voltage regulator especially adaptable for use with field-programmable gate arrays (FPGA). The voltage regulator is configurable as a true voltage regulator or, alternatively, as a pseudo-voltage regulator. The voltage regulator includes circuitry to rapidly generate an operating voltage for the core or nucleus logic elements. Additional circuitry is provided to reduce the steady-state power consumption once the operating voltage is reached. To compensate for die-to-die variations, additional circuitry is also provided to adjust the compensation delays or switching rates.

Abstract: First and second resistors are connected in series with a Zener diode between first and second points of operating potential. The base-to-emitter of an NPN transistor is connected across the first resistor to sense the current through the series path. The collector-to-emitter of a PNP transistor is connected across the second transistor, whereby when the PNP transistor is turned-on hard and into saturation, the voltage drop across the second transistor decreases. The collector of the NPN transistor is connected to the base of the PNP transistor, whereby when an overvoltage condition exists and the Zener diode breaks down, the two transistors are driven regeneratively and form a latch and the operating point of the circuit is shifted.

Abstract: A semiconductor integrated circuit device is equipped with an internal power source unit for distributing an internal power voltage level between component circuitries, and the internal power voltage level is regulated to a variable reference voltage level, wherein a first main voltage regulator regulates the variable reference voltage level to a primary reference voltage level before reaching a threshold voltage level; however, after the primary reference voltage level becomes lower than the threshold voltage level, a latching circuit supplies an activation signal to a second main voltage regulator, and the second main voltage regulator regulates the variable reference voltage level to a secondary reference voltage level so that the second main voltage regulator continuously controls the variable voltage level without any abrupt transition, thereby allowing the internal power source unit to adjust the internal power voltage level to an arbitrary point.

Abstract: A current source consists of a transistor having an emitting electrode connected to one end of a first resistor and a first operational amplifier that compares the voltage of the emitting electrode with a control voltage and controls a control electrode of the transistor through a second resistor. The voltage at the emitting electrode of the transistor is kept at a predetermined voltage by a second operational amplifier that compares the voltage at the emitting electrode with the predetermined voltage and controls the voltage at the other end of the first resistor. The control voltage source has a known source resistance. A third resistor is inserted between the non-inverting input and output terminals of the first operational amplifier. The second operational amplifier serves to make the maximum output voltage at the collecting electrode of the transistor high so that a power voltage usage efficiency of an electronic load is improved.

Abstract: A CMOS on chip mid-rail voltage generation circuit is provided for an analog ground reference. A voltage divider establishes a current path between the high and low rail, and supplies a mid-level voltage to one input of a differential amplifier. A pair of series connected field effect transistors are also connected between the high and low voltage rails, with their common connection providing the input to the other input of the differential amplifier. A pair of open loop output transistors are also coupled in series between the high and low voltage rails, and each has their gate coupled to one of the series connected pair, and is also matched to that pair.

Abstract: A switching-type voltage regulator of this invention comprises a voltage control section for generating a stabilized voltage by controlling a voltage supply period from input side to output side, and a protective device. The protective device monitors the temperature of a certain component part or parts of the voltage control section and convert the temperature into a voltage to compare with the reference voltage generated by a reference voltage source, and brings the output of the voltage control section to a halt in accordance with the result of comparison. The output of the voltage control section is brought to a halt regardless of the presence of output abnormalcy when the temperature of the component part or parts monitored exceeds a certain level. As the monitoring means, it is preferable to utilize the electrical characteristic of semiconductor p-n junction changing with temperature, and a semiconductor diode is more preferable.

Abstract: A voltage regulator comprising a first power switch connected between the input terminal and output terminal; a storage condenser connected to the input terminal via a one-way switch; a second power switch connected between the condenser and the input terminal; and a regulating element connected to the output terminal and driving the power switches in such a manner as to maintain the output voltage constant.

Abstract: A three terminal control circuit for a low dropout voltage regulator having a PNP pass transistor is provided. The control circuit is capable of pulling the base drive point down to a voltage of 3.0 volts or less to permit a current limiting resistor to be inserted between the base drive point and the base of the PNP pass transistor. The control circuit includes a pair of small-valued capacitors for providing stable operation with different output capacitors. The control circuit can also be used with p-channel FET pass transistors.

Abstract: The invention relates to a method and a circuit array for regulating the supply voltage of a load as may be found, for example, in the form of an integrated circuit in a chip card. An integrated circuit of this type contains a non-volatile memory and the control logic needed to read out the information stored in the non-volatile memory, but with the transmission of both energy and data being wireless, for example inductive. Data is transmitted by suitable modulation of the voltage supply. In order for the reader to clearly evaluate the read-out logic states, it is proposed in accordance with the invention that during output of the first logic level the supply voltage of the load is generated by serial regulation and that during output of the second logic level the terminal voltage of the voltage source is under parallel regulation.

Abstract: A programmable reference voltage generator includes a diode arrangement for generating a reference voltage in response to a control current. An array of memory cells is provided for adjusting the control current, the memory cell array including a plurality of memory cells connected to the diode arrangement through a plurality of current paths. Each of the memory cells is disposed to conduct current when programmed to store a first binary value, and to not conduct current when programmed to store a second binary value. A programming circuit is used to store a selected one of the first and second binary values in each memory cell, thereby causing the reference voltage to assume a selected magnitude.

Abstract: A power-supply arrangement comprises a reference circuit for generating a reference voltage (Vref). The reference circuit is coupled between a first (1) and a second (2) supply voltage terminal for receiving a supply voltage. A stabilizing circuit (4) generates a stabilization voltage (Vstab) related to the reference voltage and has an input terminal for receiving the reference voltage, a common terminal (7), and an output terminal for supplying the stabilization voltage. A switching stage (10) is switched depending on the supply voltage and comprises at least one switching element coupled between the input terminal and the common terminal. A current source is switched depending on the supply voltage and is coupled between the second supply voltage terminal and the common terminal. A capacitor is coupled between the common terminal and the first supply voltage terminal, and a buffer stage is coupled between the common terminal and the output terminal.

Abstract: Feedback resistors including a dividing resistor are provided at the output terminal of a switching regulator to divide an output voltage supplied by the switching regulator. The terminals of at least one of the feedback resistors are connected to the collector and emitter respectively of a transistor, and the base of the transistor is supplied with a control signal which can be output, for example, from a controller. The transistor is switched ON in response to the control signal when a load requiring a high operating voltage, such as, for example, a printing unit is not operated, thereby causing the switching regulator to generate a low target voltage which is then used to generate a low operating voltage by a linear regulator (for powering loads requiring the low operating voltage). The transistor is switched OFF in response to the control signal when the load requiring the high operating voltage (e.g.

Abstract: An AFC switch circuit is controlled by an select input logic signal for providing a selected output signal to control the local oscillator in a miniature FM receiver. The output signal has a voltage equal to either an AFC signal voltage for AFC operation of the receiver, or a reference voltage for synthesized operation of the receiver. The AFC switch circuitry employs bipolar transistors in current mirror configurations to minimize voltage offset and to enhance isolation between the unselected input and the output while operating on a power supply voltage less than 3 volts.

Abstract: A current regulator providing a highly accurate bidirectional output current, proportional to a control voltage (V.sub.i) and suited to monolithic integration is disclosed. The regulator uses a clocked integrator which integrates an error charge, arrived at by taking a precisely ratioed sample charge proportional to a voltage drop (V.sub.F), free of its common mode voltage, which is in turn proportional to the load current, and one proportional to the control voltage (V.sub.i), and combining them subtractively to form the error charge. The arrangement uses two small charge ratioing capacitors charged respectively to V.sub.F and V.sub.i, and a slightly larger integrating capacitor. The clocking is at a 10 KHZ rate. High impedance circuitry is utilized so that highly accurate, integrated capacitors of modest size and high relative accuracy may be used. These establish a regulator transfer function of high accuracy.

Abstract: In a switching regulator, input voltage is applied to a primary coil of a transformer through a location between a collector and an emitter of a switching transistor connected in series to the primary coil of the transformer. A pair of output terminals are connected to a secondary coil of the transformer through a rectifier smoothing circuit. A comparator compares output voltage occurring between the output terminals with reference voltage to generate an output signal. On the basis of the output signal, a control circuit applies a drive control signal to a base of the switching transistor. The reference voltage is given such that first voltage maintained substantially constant and second voltage such as outside input voltage or the like capable of being regulated over a relatively large varying width are added to each other.

Abstract: A series type d.c. power source circuit having a comparator for comparing a voltage detected by a current detector with a reference voltage and generating an overcurrent detection signal; and a controller connected in series with a power source line for controlling a d.c. output and executing an overcurrent protection operation, wherein one of a d.c. output division voltage and an output voltage and an oscillator circuit is mainly used as the reference voltage of the comparator, and the output voltage of the oscillator circuit is used during the overcurrent protection operation.

Abstract: An adjustable power converter which allows the output voltage of the power converter to be controlled linearly by a programming resistor or a programming voltage is provided. The adjustable power converter includes a linear programming circuit which generates a current as a linear function of the programming voltage or the resistance of the programming resistor. The current is connected to the feedback loop of a conventional power converter such that the output voltage of the power converter is a linear function of the current. As a result, the output voltage of the power converter can be linearly adjusted by adjusting the programming voltage or the programming resistor.

Abstract: A voltage reference circuit maintains two nodes at constant voltages with respect to a reference by means of a tapped divider chain in parallel with a floating voltage reference circuit, both of which feed into the output node of a single differential amplifier. The reference circuit maintains a constant voltage across the divider chain and the amplifier floats the divider up or down to maintain a node in the chain at the reference voltage.

Abstract: An internal supply voltage generator receiving an external supply voltage, generates a stable, constant internal supply voltage to be applied to a semiconductor memory device regardless of the variation of the temperature. For this end, the generator includes a voltage sharing circuit (80) which has a first variable resistor (R.sub.1 ') with higher resistance as a load element and a second variable resistor (R.sub.2 ') with lower resistance as a driving element. As the temperature increases, the resistance of the first variable resistor (R.sub.1 ') increases, thereby decreasing the current flow formed therethrough. Then, the comparator (60) connected to the output of the voltage sharing circuit (80) allows the output circuit (70) to increase the internal supply voltage, in response to increase of the temperature.

Abstract: A semiconductor device drive circuit is provided for turning on and off a semiconductor device that comprises a main static induction transistor and a sense static induction transistor. The drive circuit comprisees a first current source having one terminal connected to a power supply and its other terminal connected to said main static induction transistor, a second current source having one terminal connected to the power supply and its other terminal connected to said sense static induction transistor, a third current source having terminal connected to the power supply and its other terminal connected to the first current source, and a fourth current source having one terminal connected to the power supply and its other terminal connected to the second current source.

Abstract: A bandgap voltage generator useful in CMOS integrated circuits using intrinsic bipolar transistors. The generator is comprised of a pair of bipolar voltage generator which utilizes bipolar devices in a common collector configuration. Therefore for the first time a bandgap voltage reference using the intrinsic vertical bipolar transistor can be implemented in a CMOS chip without the need for an operational amplifier.

Abstract: A technique for operating a common emitter circuit from a plurality of supply voltages. In one embodiment, a current mirror includes a plurality of diode-connected transistors each connected between a source of current and associated supply voltages. Corresponding current mirrors are each connected between an output terminal associated supply voltage leads, thereby providing an output current mirrored from the soure of current, regardless of which of the supply voltages are activated, and regardless of their particular levels. In another embodiment, a regulator includes an output transistor having a plurality of current handling terminals, each connected to an associated supply voltage, and a second current handling terminal coupled to an output terminal.

Abstract: A voltage converter having switchable output capability is provided. The voltage converter converts an unregulated voltage input to a regulated DC voltage output. The regulated DC output level is selectable by changing the logical status of at least one logic input to the voltage converter, thereby converting a single voltage source to one of at least two selectable DC voltage outputs.

Abstract: A BiMOS voltage reference circuit which includes a bandgap circuit for providing a predetermined voltage at an output of the circuit that is independent of temperature. A start-up and bias circuit coupled to the bandgap circuit for providing a start-up current to the bandgap circuit during power-up and for providing a bias current to the bandgap circuit after power-up. A feedback circuit coupled to the bandgap circuit for maintaining the bias current to the bandgap circuit independent of power supply variations wherein the predetermined voltage at the output of the circuit is also independent of power supply variations as well as temperature.

Abstract: The invention relates to a circuit intended to supply a reference voltage comprising a voltage generator (REF) provided with a supply terminal and an output for supplying a voltage having a given nominal value (V.sub.R) and comprising a differential amplifier (A), fed by a first supply voltage, whose non-inverting input is connected to the output of the voltage generator (REF). An output of the differential amplifier (A) is connected to an input of a follower stage (T) through a controlled switching device (1), the follower stage (T) having its input connected to the first supply voltage through a first resistor (R.sub.1) and having its output, which supplies the said reference voltage (V.sub.D), connected on the one hand to the inverting input of the differential amplifier (A) through a divider bridge and on the other hand to the supply termianl of the voltage generator (REF).

Abstract: There is provided a source voltage control circuit including a reference voltage generating circuit with a negative feedback circuit, a source voltage level sensing circuit for increasing the internal source voltage when the external voltage exceeds a given voltage, a first differential amplifying circuit for active operation, and a second differential amplifying circuit for stand-by operation, whereby a stable internal source voltage is produced and the slope of the internal source voltage is readily adjusted when the external source voltage exceeds the given value. The first differential amplifying circuit receives the reference voltage and the internal source voltage, controlled by a first control signal and the output of the source voltage level sensing circuit. The second differential amplifying circuit receives the reference voltage and the internal source voltage, controlled by a second control signal.

Abstract: Disclosed is a device power supply in a semiconductor test system for supplying programmed test pattern voltages to a semiconductor device under test and for current range switching of current range resistors without effecting the output voltage of the device power supply.

Abstract: An analog multiplier feedforward technique for use in the feedback loop of a switching regulator circuit is provided. The analog multiplier eliminates the necessity for the output of the error amplifier to the regulator circuit to change voltage when regulator input voltage changes, and makes "loop" gain independent of input voltage.

Abstract: An EEPROM constructed in accordance with our invention includes a voltage multiplier for generating an erase voltage and a voltage regulator circuit for controlling the magnitude of the erase voltage. The voltage regulator circuit includes means for providing a first voltage proportional to the erase voltage, means for providing a reference voltage on a reference voltage lead, and means for controlling the voltage multiplier circuit so that if the first voltage is less than the reference voltage, the voltage multiplier circuit will increase the erase voltage, but if the first voltage is greater than the reference voltage, the voltage multiplier will not continue to increase the erase voltage. The voltage multiplier includes novel capacitors and transistors constructed using standard EEPROM processing to withstand high voltages without breaking down.

Abstract: The subject invention is a power supply comprising a magnetic amplifier, filter, back-up battery, switch-over regulating circuit and error amplifier. The magnetic amplifier receives a plurality of AC pulses and controls the pulse width of the pulses. The filter converts the pulses to a DC output. The switch-over regulating circuit connects the battery to the DC output. The error amplifier monitors the DC output and provides, at its output, an error signal to the magnetic amplifier and the switch-over regulating circuit.

Abstract: A constant voltage source circuit which is provided with an output transistor (Q.sub.1) for outputting a predetermined output voltage (V.sub.0) in accordance with an input voltage (V.sub.IN) and a differential amplifier (A), and is further characterized in that the circuit further comprises a reference voltage control means which monitors variations of the input voltage (V.sub.IN) and outputs a predetermined constant voltage to the differential amplifier (A) as a reference voltage when the input voltage (V.sub.IN) is higher than, a predetermined voltage level, and a voltage varied in accordance with the variation of the input voltage (V.sub.IN) is output therefrom to the differential amplifier (A) as a reference voltage when the input voltage (V.sub.IN) falls below a predetermined voltage level.

Abstract: A power supply has the source and drain of a MOSFET arranged for connection etween an input voltage source and a load. In normal operation a bias voltage is applied to the gate to place the MOSFET in a conductive state. A difference amplifier maintains a fixed ratio between a reference voltage and the output voltage. Current limiting circuitry senses the current that the power supply provides to the load and disables the MOSFET when the current provided to the load exceeds a predetermined value. Thermal shutdown circuitry senses the operating temperature of the power supply and places the MOSFET in a nonconductive state when the operating temperature exceeds a predetermined value.

Abstract: A digital to analog converter circuit produces an output voltage which includes a small error voltage floating on a larger direct current voltage component. The circuit includes a controlled current supply coupled to the emitter of an NPN transistor to which the direct current voltage component is supplied to the base thereof. The error voltage is generated by modulating the current through the transistor by controlling the current supply, independent of the voltage component supplied to its base, such that the output voltage occurring at the emitter of the transistor is a function of the difference between the direct current component and the natural log of the modulated emitter current.

Abstract: A voltage reference circuit (26) provides a stable output reference voltage over a wide temperature range. A high temperature curvature correction circuit (36) is enabled at a first predetermined temperature to adjust the output voltage accordingly. A low temperature curvature correction circuit (38) is enabled at temperatures below a second predetermined temperature to similarly affect a output voltage. The preferred embodiment, the high and low curvature correction circuits (36, 38) are operable to vary the current through one or more resistors in a bandgap circuit (26) or other reference circuit.

Abstract: Semiconductor device protection circuit (10) provides increased power dissipation (current) limits for FET (11) when lower FET temperatures exist. The FET drain to source voltage (V.sub.DS) is monitored to provide a current sense signal (54). When the current sense signal exceeds a predetermined reference limit signal (V.sub.REF,55), a control circuit (23, 32) reduces current (power dissipation) in the FET. Circuitry (24) provides the reference limit signal (V.sub.REF) with a predetermined temperature variation as a function of the sensed temperature of the FET whereby for low device temperatures higher power dissipation (current) limits for the FET are provided. An additional control circuit (21, 30) provides short circuit overcurrent protection by reducing current in the FET when sensed FET current exceeds a predetermined limit. A delay circuit (39) inhibits operation of at least the control circuit (20, 32) until a predetermined time (t.sub.1) after the FET is turned on.

Abstract: An error amplifier is disclosed for use in linear or switched-mode voltage or current regulators that use a transconductance type power-amplifier, enabling easy modular parallel connection of said regulators by simply parallel wiring of normally externally accessible nodes of the individual regulators: power-input, power-output, error amplifier output, and error amplifier input, to boost the system's total output power by about equally sharing the total output power among the individual regulators, includinga. an amplifier with grossly asymmetric output current capability in sink and source directions; andb. a sense circuit to slightly modify the voltage on the reference input of the said amplifier when the lower value output current limit becomes active so that it causes positive feedback thereby ensuring that at any time only one of the plurality of parallel operated amplifiers is active and controls the system's output while all the other amplifiers are in current limit and thereby inactive.

Abstract: A regulator circuit for use with a connectorless power supply system in which power is inductively supplied to a plurality of remote loads. A sinusoidal current, at a frequency of 38 kHz, is provided by a power distribution system (10), and circulates through a supply loop (68), which is disposed under the floor of an aircraft cabin. Three parallel connected capacitors (78, 80, and 82) and a multi-turn coil (70) that is inductively coupled to the supply loop comprise a resonant tank circuit in which current circulates. The voltage developed across the tank circuit is half wave rectified, filtered, and supplied to a load connected circuit. An op-amp (134) compares the potential across the load to a regulated voltage. The output of the op-amp is used to control the period of time during which an N channel FET (96) shunts current to regulate the output voltage.

Abstract: A circuit is provided for realizing multiple precision resistor elements on an integrated circuit by sensing a reference resistor. The circuit contains a first current source which passes a first current through a reference resistor located either on or off of the integrated circuit to generate a reference voltage. The reference voltage is applied to the inverting input of a precision high gain operational amplifier. A second current source is connected to the drain of a first MOS transistor operating in its ohmic region. The second current source is also connected to the non-inverting input of the high gain operational amplifier. The output of the operational amplifier is electrically connected to the gate of the first and second MOS transistors. In operation, a precision resistance is developed across the second MOS transistor which is equal to or some determinable multiple of the resistance of the reference precision resistor located on or off chip.

Abstract: A power voltage regulator circuit has a power terminal to which an external power voltage is supplied, an output line, and a voltage-drop circuit connected between the power terminal and the output line. The voltage drop circuit includes an N-channel MOS transistor having a drain connected to the power terminal and a source connected to the output line, a constant voltage generator for supplying a voltage, lower than the external power voltage, to a gate of the MOS transistor, and a semiconductor well whose surface area serves as a channel region of the MOS transistor.

Abstract: An input buffer circuit for providing corresponding CMOS compatible signals to an input signal. The input buffer circuit is comprised of a switched-capacitor voltage division network for providing a reference voltage to a comparator. The comparator accepts an input voltage and determines if the input voltage is greater or less than the reference voltage and generates a CMOS compatible output, which is determined by the value of the input signal in reference to the reference voltage. The reference voltage generator is comprised of two capacitive devices, wherein the first capacitive device is charged and the second capacitive device is discharged during a first time period and the charges on the two capacitive devices are shared during a second time period. A ratio of the capacitances of these two capacitive devices determines the voltage value at the junction of the two capacitors, which then determines the reference voltage.

Abstract: A voltage regulator fabricated on an integrated circuit chip to provide regulated voltage for the chip assures that the integrated chip is operational before conventionally provided external regulated voltages are available. This enables the integrated circuit chip to be used to monitor the external regulated voltage supplies and prevents latch-up of the integrated circuit due to improper voltages being applied during power sequencing.

Abstract: A following voltage/current regulator includes a field effect transistor (FET) (48) connected in series between an unregulated voltage source (44) and a load, such as a motor bridge circuit (50). The conduction of the FET is controlled by a control circuit (56) which measures the input voltage to the FET source, the output voltage from the FET drain and the current drawn by the load. Initially, when power is turned on, the inrush current to the load is limited until a predetermined voltage differential between the input and output voltages is achieved at steady state. Then, the voltage regulator maintains the predetermined voltage differential to provide a well regulated output voltage to the load despite fluctuations in supply voltage. This "following" action limits the heat disipation and protects the FET. Because the voltage regulator uses no inductors or transformers, there are no saturation problems and the circuit may be compactly packaged.

Abstract: A constant-voltage regulated power supply circuit has an input circuit and an output circuit. The sense circuit includes a programmable sense circuit that further includes a divider network with a plurality of selectable tap points and a multiplexer having a plurality of inputs and an output with each tap point being connected to an individual input of the multiplexer. A controllable pass element is operatively connected in the power supply circuit between the input circuit and the output circuit. A comparator connected to receive inputs from a selected tap point and a reference voltage generating circuit provides an output to control the controllable pass element.

Abstract: In a dc-to-dc converter, alternating current or pulsating direct current produced by a cyclically switched power supply passes through semiconductor rectifiers or diodes. The rectifiers may be subject to unwanted conduction characteristics attributable to charge storage, which may result in cyclical current spikes during normal operation. A current sensor is coupled to sense a current which includes the cyclical spikes. A controllable attenuator or gain element couples the sensed current in a feedback loop to shut down the converter in the event of an overcurrent. To reduce the possibility of shut-down due to the normal cyclical current spikes, the attenuator or gain element is cyclically switched so as to reduce the sensitivity to the current spikes when they occur.

Abstract: A bandgap reference circuit is described in which two transistors share a current with their bases coupled together and to an output terminal. A pair of resistors is coupled in series between the emitter of one of the transistors and ground, the emitter of the other transistor being coupled to a node between the resistors. A further transistor is coupled between the output terminal and the node with its base coupled to a second node between two further resistors connected in series between the output terminal and ground. The further transistor and resistors allow the circuit to be compensated for higher order temperature dependence.

Abstract: A low dropout voltage regulator with a switched redundant input, which has low dropout voltage before, during, and after a switch to the redundant input. In a preferred embodiment, the inventive voltage regulator includes two transistors that are controlled by the output of an error amplifier, and redundant input voltage sources. A first one of the transistors conducts when a first input voltage is greater than a second input voltage. The other transistor conducts when the second input voltage exceeds the first input voltage. When both input voltages are have substantially equal magnitude, both transistors conduct. In a preferred embodiment, one input voltage is supplied by a battery, and the other is supplied by a storage capacitor charged by the battery. When the battery fails, the storage capacitor will discharge, thus serving as a time-varying redundant voltage source in the event of battery failure.

Abstract: A voltage regulator powered by an electrical power source having a discharging voltage characteristic and regulating the voltage applied to an electrical load from the power source includes a stable reference voltage source, a sensor for sensing the voltage applied to the load, an error signal generator for generating an error signal related to the difference between the sensed and reference voltages, and a voltage control connected in series with the electrical load and responding to the error signal to control the voltage applied to the load as the power source discharges. The invention is particularly useful when the power source is a single cell battery and the load is a direct current motor. Embodiments of the invention may apply a substantially constant or an increasing voltage to a load as the source voltage declines according to its discharge characteristic.