Abstract: A low drop-out voltage regulator with high-performance linear and load regulation, comprising: a reference voltage circuit, capable of providing a reference voltage; a differential amplifier; a power device, capable of driving a load resistor; a feedback circuit, disposed between the differential amplifier and the power device so that the differential amplifier outputs a correction voltage after the reference voltage and a feedback voltage across the feedback circuit; and a voltage buffer for frequency compensation, disposed between the differential amplifier and the power device, the voltage buffer comprising a complementary type buffer.

Abstract: The output current of a power converter is sensed for triggering a quick transient response when the variation of the output current reaches a default value, and therefore the output voltage of the power converter is promptly stabilized earlier by removing the time delay to trigger the quick transient response.

Abstract: A method and circuit for providing a soft start-up process for an amplifier circuit to reduce or prevent destructive overshoot of an output voltage are provided. In accordance with an exemplary embodiment of the present invention, an exemplary method and circuit are configured to suitably momentarily replace an actual fixed reference voltage with a second reference voltage during the start-up process. Such a method and circuit can provide a fast start-up process without destructive overshoot and without affecting or compromising any control loop of the amplifier circuit, and can be configured within various applications. In accordance with an exemplary embodiment, an exemplary amplifier circuit is configured with a soft-start circuit, with the soft-start circuit configured to provide a secondary reference voltage during initial start-up before switching to an actual reference voltage.

Abstract: A current generator is provided, including a bandgap circuit, an operational amplifier, and an output resistor. The bandgap circuit is used to output a bandgap reference voltage insensitive to environment temperature and supply voltages. The operational amplifier has a positive input receiving the bandgap reference voltage, a negative input, and an output connected to the negative input to obtain an output voltage substantially equal to the bandgap reference voltage. The output resistor is connected to the output of the operational amplifier serially to generate an output current flowing through the output resistor. Thus, the output current generated by the current generator is insensitive to environment temperature and supply voltages, and therefore more accurate and stable.

Abstract: A power supply circuit includes a standard voltage generator, a regulator, a capacitor and a discharging circuit. The standard voltage generator is configured to generate a standard voltage. The regulator is configured to control an output voltage by use of a reference voltage based on the standard voltage outputted from the standard voltage generator, and to be capable of being switched ON/OFF. The capacitor is connected in parallel to the regulator between the standard voltage generator and the regulator. The discharging circuit is configured to discharge electrical charges from the capacitor while the regulator is in an OFF state.

Abstract: Implementations related to low drop output (LDO) circuit arrangements are presented herein.

Abstract: A hard saturation mode of operation can be avoided in an LDO regulator by providing an additional feedback control loop. The additional control loop cooperates with the LDO regulator's amplifier stage and output stage to maintain at least a minimum desired voltage drop across the output stage from the power supply to the load.

Abstract: A method for providing precise current regulation and limitation for a power supply is provided. The method includes amplifying any difference between a load current signal and a current setting reference signal with a feedback loop amplifier to generate a feedback signal. A power output signal is generated based on the feedback signal. An output signal for the power supply is generated based on the power output signal. The load current signal and the current setting reference signal are generated based on the power output signal. An offset error signal is generated based on the load current signal and the current setting reference signal. A differential bias for the feedback loop amplifier is adjusted based on the offset error signal.

Abstract: A constant-voltage power supply circuit is disclosed that is able to prevent overshoot of an output voltage possibly occurring when changing a constant-voltage circuit in operation and is able to supply a constant output voltage. The constant-voltage power supply circuit includes a first constant-voltage circuit, having a first output transistor and a first output voltage controller, that generates a first reference voltage and generates a first proportional voltage in proportion to a voltage on an output terminal, and a second constant-voltage circuit having a second output transistor and a second output voltage controller that generates a second reference voltage and generates a second proportional voltage in proportion to the voltage on the output terminal.

Abstract: An LDO (low dropout) regulator including a pass transistor having a first electrode coupled to produce an output voltage of the LDO regulator, a control electrode, and a second electrode coupled to receive an input voltage of the LDO regulator. An error amplifier has a first input coupled to a first reference voltage and an output coupled to the gate control electrode of the pass transistor. A first feedback circuit has an input coupled to the first electrode of the pass transistor and an output producing a first feedback voltage coupled to a second input of the error amplifier. The auxiliary amplifier has a first input coupled to a second reference voltage and an output coupled to the output of the error amplifier. A second feedback circuit has an input coupled to the output of the auxiliary amplifier and an output producing a second feedback voltage coupled to a second input of the auxiliary amplifier.

Abstract: A linear regulator and methods of regulation are provided. In one implementation, a linear regulator is provided that includes a mode selection circuit operable to determine whether a power source voltage received by the linear regulator exceeds a pre-defined operational range of a load in communication with the linear regulator, and a power switch to directly supply the power source voltage to the load if the power source voltage is within the pre-defined operational range.

Abstract: A voltage regulating circuit for providing a regulated output voltage. The voltage regulating circuit includes a voltage regulator, a converting circuit, a capacitive device, a first current mirror module, and a second current mirror module. The voltage regulator has a first output producing the regulated output voltage and a second output producing a pass voltage. The converting circuit converts the pass voltage into a first current and a second current passing through a first converting node and a second converting node respectively, where the first current charges/discharges the capacitive device. The first current mirror module has a first current mirror path coupled to the first converting node and a second current mirror path coupled to the second converting node. The second current mirror module has a first current mirror path coupled to the second converting node and a second current mirror path coupled to the first output.

Abstract: Power regulator circuitry for programmable memory elements on programmable logic device integrated circuits is provided. The programmable memory elements may each include a storage element formed from cross-coupled inverters and an address transistor. Address drivers may be used to supply address signals to the address transistors. The power regulator circuitry may include an address power supply circuit that produces a time-varying address power supply voltage to the address drivers and storage element power supply circuits that provide time-varying storage element power supply voltages to the cross-coupled inverters in the storage elements. Unity gain buffers may be used to distribute a reference voltage from a bandgap voltage reference to the power supply circuits. The power supply circuits may use voltage dividers and p-channel metal-oxide-semiconductor control transistors.

Abstract: A differential amplifier receives a reference voltage and a divided voltage dividing an output voltage, and outputs a control voltage in accordance with the difference between the reference voltage and the divided voltage. The control voltage output from the differential amplifier is supplied to an output amplifier. The output amplifier generates a stabilized output voltage from a high-potential-side power supply voltage in accordance with the control voltage. A P-type MOS transistor is connected to a node of the output voltage, and the MOS transistor carries a current from the node of the output voltage. A current control circuit controls a gate of the P-type MOS transistor so that the current flowing through the P-type MOS transistor becomes a constant value.

Abstract: An integrated circuit assembly includes a voltage level generator, a level shifter, a bandgap reference generator and a voltage regulator. The voltage level generator generates output voltage level signals in response to a supply voltage. The level shifter receives the output voltage level signals from the voltage level generator and generates first and second sets of control signals. The bandgap reference generator receives a reference voltage input and generates a bandgap reference signal. The voltage regulator receives a supply voltage, the bandgap reference signal the first and second sets of control signals from the level shifter and generates a constant output voltage under varying circuit conditions.

Abstract: A regulator circuit is provided which suppresses a variation in output voltage upon occurrence of a variation in input voltage or output current without any increase in steady-state power consumption.

Abstract: A high-speed voltage regulating apparatus and a method for high-speed voltage regulation. The apparatus includes: (A) a regulator, adapted to provide a regulated voltage; (B) switching circuitry, connected to the regulator, adapted to either (i) connect the regulator to an output node or (ii) disconnect the regulator from the output node; whereas the output node is connected to a dynamic power consuming device and to a load capacitor; (C) control logic, connected to the regulator, adapted to receive at least an indication reflecting a voltage of the output node and to control the switching circuitry such that the regulator is disconnected from the output node to facilitate a decrease in the voltage of the output node.

Abstract: The present invention is related to a dc/dc converter. A dc/dc converter according to the present invention comprises an inductor, a switch unit connected to both ends of the inductor and charging or retrieving an energy into the inductor, an output unit comprising an output switch unit outputting the energy charged in the inductor into an output end and a first comparison unit controlling an on-off of the output switch unit, a freewheeling switch unit connected to both ends of the inductor and returning a residual current remained in the inductor, a current sense unit sensing the residual current, an offset current generation unit generating an offset current, an error amplifier comparing the residual current inputted from the current sense unit to the offset current generated in the offset current unit and outputting the error signal, and a control unit controlling the switch unit with the error signal inputted from the error amplifier.

Abstract: A low drop-out DC voltage regulator for regulating a voltage from a DC power supply applied to a load at an output of the regulator and comprising a pass device for controlling flow of current from the power supply to the load so as to control the output voltage at the regulator output, and a feedback loop for controlling the pass device. The feedback loop comprises a resistive feedback path and a capacitive feedback path that includes a feedback capacitive element in series, and comparator means responsive to signals from the feedback paths for applying to the pass device an error signal that is a function of the value of the output voltage relative to a nominal value so as to control the output voltage.

Abstract: A constant voltage circuit that is capable of realizing high speed response with respect to an abrupt change in an input voltage or a load current is disclosed. The constant voltage circuit includes a first error amplifier with a high direct current gain and a second error amplifier with high speed responsiveness with respect to a change in an output voltage. The constant voltage circuit uses the first and second error amplifiers to conduct operation control of an output voltage control transistor in response to a change in the output voltage.

Abstract: A constant voltage circuit which is capable of quickly responding to a sudden change of an output voltage includes an output transistor, and first and second error amplifiers. The output transistor outputs a power with an output voltage and an output current to a load. The first error amplifier is configured to increase a response speed with respect to changes of the output voltage in accordance with an increase of the output current so as to control operations of the output transistor. The second error amplifier has a response speed faster than the first error amplifier with respect to changes of the output voltage, and is configured to decrease a gain thereof in response to a drain current of the output transistor.

Abstract: A voltage regulator circuit and control method therefor. The circuit includes input and output terminals, an output transistor to pass a current from the input terminal to the output terminal according to a control signal, a reference voltage generator unit to generate and output a reference voltage, an output voltage detector unit to detect an output voltage output from the output terminal and generate and output a proportional voltage proportional to a detected voltage, a first error amplifier unit to control the output transistor to make the proportional voltage equal to the reference voltage, and a second error amplifier unit to respond to fluctuation in the output voltage faster than the first error amplifier unit and increase the output current from the output transistor for a period of time when the output voltage rapidly drops. Current consumption of the second error amplifier unit is changed according to the output current.

Abstract: A hysteretic regulator is provided. The hysteretic regulator includes a delay compensation circuit that adds a delay to the output of the hysteretic comparator. The delay is dependent on the input voltage. For low duty cycles, the slope of the inductor current is much greater for the rising edge than it is for the falling edge. The delay compensation circuit adds sufficient delay to the falling edge so that the undershoot cancels the overshoot.

Abstract: A series regulator circuit that enables accurate detection of the rising of an output voltage even when the output voltage fluctuates. The series regulator circuit uses an operational amplifier including a first constant current source, first and second transistors for distributing the current of the first constant current source, and a third transistor connected to the second transistor The gate terminals of the first and second transistors are respectively supplied with a reference voltage and a negative feedback voltage. Output of the operational amplifier is amplified by an amplifier. A fourth transistor forms a current mirror circuit with the third transistor. A second constant current source forms a current comparator with the current that flows to the fourth transistor. A connection node of the fourth transistor and the second constant current circuit is connected to the input terminal of an inverter. The output from the inverter is used as a power-up detection signal.

Abstract: A constant-voltage power supply circuit is disclosed that is able to prevent overshoot of an output voltage possibly occurring when changing a constant-voltage circuit in operation and is able to supply a constant output voltage. The constant-voltage power supply circuit includes a first constant-voltage circuit, having a first output transistor and a first output voltage controller, that generates a first reference voltage and generates a first proportional voltage in proportion to a voltage on an output terminal, and a second constant-voltage circuit having a second output transistor and a second output voltage controller that generates a second reference voltage and generates a second proportional voltage in proportion to the voltage on the output terminal.

Abstract: A regulated voltage is generated at an output terminal of a voltage regulator circuit having at least one input terminal. A feedback signal is coupled from a first transistor coupled in parallel with a first resistor between the output terminal and the input terminal. The feedback signal is coupled to the input terminal to regulate the stability of the voltage regulator circuit. In a method of operation, the stability of a circuit is regulated by generating a feedback signal in the circuit to add a zero to a transfer function and raise an open loop phase curve of the circuit to result in a better power signal rejection ratio over a frequency range for the circuit.

Abstract: A voltage regulator circuit has a first amplifier stage with input and output terminals, a feedback terminal, a pole-inducing transistor, and a compensating network coupled to the output terminal. A second amplifier stage has an input coupled to the first amplifier output, first and second current mirrors, and a pass transistor.

Abstract: A voltage regulator includes first and second closed-loop amplifiers and a N-type transistor. The first amplifier receives a first reference voltage and a feedback voltage. The second amplifier is responsive to the first amplifier and to the regulated output voltage of the regulator. Both amplifiers are biased by a biasing voltage. The second amplifier has a bandwidth greater than the bandwidth of the first amplifier and a gain smaller that the gain of the first amplifier. The N-type transistor has a first terminal responsive to the output of the second amplifier, a second terminal that receives the input voltage being regulated, and a third terminal that supplies the regulated output voltage. The feedback voltage is generating by dividing the regulated output voltage. An optional fixed or dynamically biased current source biases the first terminal of the N-type transistor. The voltage regulator optionally includes an overshoot correction circuit.

Abstract: A capacitor multiplier including a capacitor, a first voltage follower, a first impedance element, and a second impedance element is provided. The input terminal of the first voltage follower is electrically connected to the first terminal of the capacitor. Wherein, the voltage level of the output terminal of the first voltage follower changes along with the voltage level of the input terminal thereof. The first terminal of the first impedance element is electrically connected to the first terminal of the second impedance element. The second terminal of the first impedance element is electrically connected to the first terminal of the capacitor. The second terminal of the second impedance element is electrically connected to the output terminal of the first voltage follower.

Abstract: The present invention provides an LDO regulator having a greatly improved overshoot characteristic through the use of an output voltage based feedback loop. More specifically, in the invention, one or more resistors in the divider network in a conventional LDO regulator is replaced with a variable resistor. By varying the resistance of the variable resistor as a function of the output voltage of the LDO regulator, the closed-loop gain of the LDO amplifier may be modulated in such a way as to reduce overshoot in the output voltage of the LDO regulator. In particular, the targeted final output voltage value may be arbitrarily lowered for a predetermined period of time, so that the LDO regulator output may rapidly reach a steady state voltage that is very close to the final desired regulating value without exceeding the final desired regulating value during regulator startup.

Abstract: An oscillation sensor for a regulator that provides dynamic control of a connection/disconnection of a compensation capacitance. The compensation capacitor is disconnected under normal operation and is automatically connected if oscillation is detected in the output and regulator's error amplifier. In this way, oscillations are stopped in the regulator almost immediately after it occurs. Also, once the circuit is stable again, the compensation capacitor is quickly disconnected again. Consequently, the compensation capacitor does not adversely affect the overall performance of the regulator.

Abstract: An LDO (low dropout) regulator including a pass transistor having a first electrode coupled to produce an output voltage of the LDO regulator, a control electrode, and a second electrode coupled to receive an input voltage of the LDO regulator. An error amplifier has a first input coupled to a first reference voltage and an output coupled to the gate control electrode of the pass transistor. A first feedback circuit has an input coupled to the first electrode of the pass transistor and an output producing a first feedback voltage coupled to a second input of the error amplifier. The auxiliary amplifier has a first input coupled to a second reference voltage and an output coupled to the output of the error amplifier. A second feedback circuit has an input coupled to the output of the auxiliary amplifier and an output producing a second feedback voltage coupled to a second input of the auxiliary amplifier.

Abstract: A voltage supply circuit having variable drive strength can optionally be used to provide improved phase margin in an integrated circuit. A bandgap circuit drives an operational amplifier, with the second input of the operational amplifier being a regulated voltage node. The operational amplifier drives multiple pull-ups in a pull-up network coupled to the regulated voltage node, of which the different pull-ups can be separately enabled to control the effective channel width of the pull-up network. In some embodiments, a control circuit (e.g., one or two additional operational amplifiers driving a counter) accepts the output of the operational amplifier as an input signal and provides multiple enable signals to the pull-up network.

Abstract: A system in which drooping of the video levels due to leakage currents and proper DC bias level is addressed by providing a charge into the video signal to offset the leakage currents and to provide DC bias. To determine the leakage current level, measurements are made measuring the voltages of the syncs and the blanking intervals. To determine the DC bias, a measurement is made of the sync. Over a series of video lines these measurements are averaged. If the average is below the desired level, a charge is provided via a current source to the incoming signal. By having the current source provide charge during each video line, droop is reduced and the proper DC bias is provided.

Abstract: A control circuit for a DC voltage supply is provided that includes a circuit, an error amplifier and modulator. The circuit is operable to measure a voltage difference between a negative voltage rail and a ground reference in the DC voltage supply. The circuit is further operative to create an offset voltage proportional with the measured voltage difference. The circuit is further yet operative to add the offset voltage to a reference voltage to create a modified reference voltage. The error amplifier has a first input coupled to receive the modified reference voltage and a second input coupled to a positive voltage rail in the DC voltage supply. The error amplifier further has an output. The modulator is coupled to the output of the error amplifier. The modulator is operative to maintain the positive rail at a select value corresponding to the modified reference voltage.

Abstract: A adaptive pole and zero and Pole-Zero Cancellation Control Low Drop-Out (LDO) regulator is provided, which includes a regulation unit, an error amplifier, a Miller Effect Pole control unit, a Pole Zero Cancellation delay unit, and a feedback network. Pole and Zero could be adaptive regulated depend on various loads and maintain stably in a perfect phase margin.

Abstract: A regulator circuit having a voltage output terminal is provided. The regulator circuit includes a current mirror module, a plurality of source followers, and a switch. The current module receives a driving voltage, and has a first current terminal coupled to a driving current and a plurality of second current terminals, so that the driving current is copied to each second current terminal. Furthermore, each of second current terminals is coupled to one of source followers respectively. An output terminal of each source follower is coupled to an input terminal of next source, and the input terminal of the first source follower receives a control voltage. So that the source followers can determine whether the switch conducts the driving voltage to the voltage output terminal or not according to the copied driving current and the control voltage.

Abstract: A digitally controlled device is provided to interface between a user of adjustable power unit and an adjustable power module, where the user provides an analog user input signal for adjusting the performance of the adjustable module using a user defined standard. The digitally controlled device provides the adjustable power module an analog input signal adapted to the standard used by the module. The digital controller device for controlling adjustable power module that comprises at least one analog to digital converter for converting analog user input signal to digital input, a micro-controller adapted to receive the input digital information and operate at least one digital to analog unit in response to the digital input information and at least one digital to analog converter unit adapted to produce analog input signal for controlling adjustable module.

Abstract: A power circuit and a charge pumping circuit add one control switch of small size to control a power transistor, and save one switch of large area and one capacitor of large area as compared with a conventional power circuit and a conventional charge pumping circuit. The power circuit includes a power processing circuit, a linear voltage-regulating switch, and a capacitor. The linear voltage-regulating switch includes a power transistor and a control switch. The control switch has a first end coupled to a gate of the power transistor and a second end coupled to one of a drain and a source of the power transistor. When the control switch is “on”, the power transistor is “off”. When the control switch is “off”, the voltage on the drain of the power transistor is maintained at a predetermined value by the linear voltage-regulating switch.

Abstract: A constant-voltage circuit includes a first transistor, a first control circuit, and a second control circuit having a second transistor and a differential amplifier. The first transistor controls an output current according to a first control signal output by the first control circuit such that an output voltage is substantially equal to a predetermined voltage. The second control circuit has a response property faster than the first control circuit to a variation of the output voltage, and causes the first transistor to increase the output current for a predetermined time period, regardless of the first control signal, when the output voltage varied to an extent greater than a predetermined output voltage variation value. The second transistor controls an operation of the first transistor according to a second control signal output by the differential amplifier such that a voltage at an inverting input terminal is substantially equal to the bias voltage.

Abstract: An LDO regulator includes two linear regulator circuits and an internal priority logic scheme that favors generating a regulated output voltage using a regulated supply voltage over an unregulated supply voltage. The unregulated supply voltage is applied to a first input terminal from a raw voltage source. The regulated supply voltage is applied to a second input terminal from, for example, a switching (e.g., BUCK) regulator. Two output devices are respectively connected between the first and second input terminals and the LDO output terminal. The first regulator circuit causes the first output device to supply the desired regulated output voltage while the switching regulator ramps up. Once the regulated supply voltage is high enough to allow regulation, the internal priority logic scheme disables the first regulator circuit, whereby the desired regulated output voltage is generated solely by the second regulator circuit through the second output device.

Abstract: In one embodiment, an error amplifier of a power supply controller is configured to receive a current sense signal prior to the current sense signal undergoing amplification.

Abstract: A constant voltage circuit that is capable of realizing high speed response with respect to an abrupt change in an input voltage or a load current is disclosed. The constant voltage circuit includes a first error amplifier with a high direct current gain and a second error amplifier with high speed responsiveness with respect to a change in an output voltage. The constant voltage circuit uses the first and second error amplifiers to conduct operation control of an output voltage control transistor in response to a change in the output voltage.

Abstract: A linear voltage regulator provides a regulated load voltage to a load. In a preferred embodiment, the linear voltage regulator includes: a regulating circuit for receiving an input voltage and providing an output voltage to a load, the regulating circuit being driven by a driving voltage; and two resistors connected to each other in series receiving the output voltage and providing an adjusting current to the regulating circuit. The linear voltage regulator is capable of providing a greater current to the load, and having a wide range of input voltages.

Abstract: Constant voltage regulator includes an output terminal, an output transistor, an output voltage controller, and a switching circuit. The output terminal outputs a first voltage to an external host apparatus. The output transistor outputs a current in accordance with a signal. The output voltage controller amplifies a difference between a reference voltage and a feedback voltage produced in proportion to the first voltage, and outputs the amplified voltage to the control gate of the output transistor. The switching circuit selectively outputs one of a second voltage greater than the first voltage and a third voltage greater than the second voltage to a substrate gate of the output transistor in response to an operation mode switchable between a first mode in which an output current to the external host apparatus is smaller than a predetermined value and a second mode in which the output current is greater than the predetermined value.

Abstract: A DC power supply control apparatus monitors respective terminals supplying positive and negative DC supply voltages to a utility device. The voltage at the negative terminal is compared with a target value for that voltage to produce an offset current representative of any voltage differential therebetween. This offset current is used to produce an offset voltage, that is added to or subtracted from a target value of the positive supply voltage to produce an error amplifier reference voltage. This reference voltage is compared with the voltage at the monitored positive terminal, to produce an error voltage, in response to which the power supply's modulator loop adjusts the power supply's positive output voltage, as necessary, to maintain the intended DC voltage differential between the positive and negative DC supply voltages.

Abstract: The present invention is a LDO voltage regulator circuit with common-mode feedback. The LDO voltage regulator includes an error amplifier with a common-mode feedback unit, a pass device and a compensation circuit. A signal from the pass device acts as an input signal to the error amplifier and is compared with another input signal, producing a differential signal. The differential signal is amplified and then provided to the pass device. A capacitor in the compensation unit provides frequency compensation to the LDO voltage regulator. The common-mode feedback unit incorporated into the error amplifier greatly improves a slew rate of a gate voltage of the pass device.

Abstract: Control loops in a voltage regulator can be stabilized using minimal silicon area. A current limit signal, generated by a current limit control loop in the voltage regulator, can be divided to minimize a zero provided in a compensation set associated with a voltage control loop, thereby stabilizing both loops. The compensation set can include a resistor (the zero) and a capacitor (a pole) connected in series between output and input terminals of an amplifier. Dividing the current limit signal can include injecting a first portion of the current limit signal on a first side of the resistor and injecting a second portion of the current limit signal on a second side of the resistor. The ratio of the first and second portions can be based on a gain of the amplifier, thereby minimizing an effect of the resistor.

Abstract: A low drop out (LDO) regulator that includes a novel error amplifier, which is arranged with a first stage that employs both NMOS and PMOS devices that are similarly doped in differential pairs and a second stage that operates with NMOS and PMOS devices in a push-pull arrangement. In addition to the error amplifier, the LDO regulator can also include a startup circuit coupled to an enable voltage, a reference filter circuit coupled to a reference voltage, an output circuit, a quiescent current control circuit, and a pulse generator circuit. Also, an internal RC network is provided to compensate for phase shift. The integrated operation of the components of the regulator enables stable and fast operation of an LDO regulator with no external capacitors connected to the input or output terminals.

Abstract: A regulator circuit is offered to resolve a problem that an unnecessary operating current flows in a semiconductor integrated circuit in a low power consumption state. Channel width to channel length ratios of an output transistor in a first operational amplifier and a first control MOS transistor are designed large in order to obtain an operating current in a normal operation state, while channel width to channel length ratios of an output transistor in a second operational amplifier and a second control MOS transistor are designed small to obtain an operating current in the low power consumption state. There is provided a switching circuit that selectively put in operation one of the operational amplifiers according to the state of the integrated circuit. The first operational amplifier and the first control MOS transistor having higher current driving capabilities operate in the normal operation state.