Semiconductor devices for power control and power supply devices with variable output voltage

Abstract

A semiconductor device for power control and a power supply device with variable output voltage are provided. The semiconductor device for power control allows the output voltage to be varied in stages and can be switched on and off via a few external terminals. It includes: a control circuit that controls a voltage control transistor based on an output feedback voltage; a bias circuit that generates an operating voltage for the control circuit based on a DC voltage input to a voltage input terminal; and two or more external terminals for inputting and outputting control signals. The control circuit includes: an error amplifier that outputs a voltage corresponding to the potential difference between the voltage divided by a voltage divider circuit that divides the output voltage and a predetermined reference voltage; and a logic circuit that generates a signal or voltage for shifting the divided voltage input to the error amplifier based on two or more output control signals input to the two or more external terminals, and a signal or voltage for deactivating the bias circuit based on any combination of the two or more output control signals.

Description

Technical Field

[0001] This invention relates to a DC power supply device, and more particularly to an effective technology for a series regulator-type power control semiconductor device and a variable output voltage power supply device capable of multi-stage variation of output voltage. Background Technology

[0002] A series regulator (hereinafter referred to as the regulator) exists as a power supply device that controls a transistor positioned between a DC voltage input terminal and an output terminal to output a DC voltage with a desired potential. As an application of this regulator, for example, there are constant voltage power supply devices for supplying DC power to cooling fans, lighting devices, and the like installed in electronic devices. In recent years, with the increasing speed and functionality of electronic devices such as personal computers, the demand for cooling fans has also been increasing.

[0003] In electronic devices equipped with air supply devices (fans), there is a need to add the following function: to change the air supply volume, i.e., the cooling performance, by periodically altering the voltage of the motor that drives the fan. Therefore, the regulator is required to have the function of periodically changing the output voltage.

[0004] Previously, inventions involving regulators capable of changing output voltage included, for example, the invention described in Patent Document 1.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2006-320110

[0008] Patent Document 2: Japanese Patent Application Publication No. 2017-134557 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] The regulator described in Patent Document 1 can select and output three different output voltage levels based on the input level of the control voltage.

[0011] Although the regulator in this invention can switch the output voltage in stages, since the output switching is based on an arbitrary control voltage input from the outside, when a general-purpose microcomputer (hereinafter referred to as microcomputer) is used as the device to generate the input control voltage, a high-function microcomputer with a built-in D / A conversion circuit is required, which leads to increased costs.

[0012] Here, as a method for switching the output voltage in stages using a microcomputer without an internal D / A conversion circuit, multiple control signals can be input to a power control semiconductor device constituting the regulator for switching. However, in this case, the power control semiconductor device requires multiple control input terminals, thus increasing the chip size.

[0013] On the other hand, in power supply devices, in order to reduce or even eliminate standby current consumption, the power control semiconductor device constituting the regulator must have the function of being turned on and off by an external control signal. In this case, a terminal for receiving the on / off control signal from an external source needs to be additionally provided in the power control semiconductor device.

[0014] Furthermore, as a regulator semiconductor integrated circuit provided with terminals for inputting on / off control signals, there exists, for example, the circuit described in Patent Document 2. In the regulator of Patent Document 2, the bias circuit that supplies the operating voltage to internal circuits such as the error amplifier and reference voltage circuit is disconnected by an external on / off control signal, thereby stopping the operation of the regulator.

[0015] However, as described above, if terminals for inputting each signal are provided separately in order to switch the output voltage via multiple control signals and to enable the power control semiconductor device to be turned on / off from the outside via external on / off control signals, then there is a problem of increasing the number of external terminals, increasing the chip size, and consequently leading to larger packaging.

[0016] The present invention was proposed in view of the above-mentioned problems, and its object is to provide a power control semiconductor device and a variable output voltage power supply device that can change the output voltage in stages according to the control signal from the outside through a small number of external terminals and can be turned on / off.

[0017] Another object of the present invention is to provide a power control semiconductor device and a variable output voltage power supply device that can easily control the output voltage using a microcomputer without internal D / A conversion circuitry.

[0018] Methods for solving problems

[0019] To achieve the above objectives, the present invention provides a semiconductor device for power control, comprising: a voltage control transistor connected between a voltage input terminal for inputting a DC voltage and an output terminal; a control circuit that controls the voltage control transistor based on an output feedback voltage; a bias circuit that generates an operating voltage for the control circuit based on the DC voltage input to the voltage input terminal; and two or more external terminals for inputting an output control signal supplied from an external source for controlling the output voltage.

[0020] The aforementioned control circuit includes:

[0021] An error amplifier whose output corresponds to the potential difference between the voltage divided by a voltage divider circuit that divides the output voltage of the aforementioned output terminal and a predetermined reference voltage; and

[0022] A logic circuit that generates a signal or voltage for shifting the voltage divider circuit input to the error amplifier based on two or more output control signals input to the two or more external terminals, and a signal or voltage for deactivating the bias circuit based on any combination of the two or more output control signals.

[0023] According to the power control semiconductor device with the above structure, the output voltage can be varied in stages by an external output control signal. Furthermore, since the logic circuit de-energizes the bias circuit that generates the operating voltage of the control circuit based on any combination of two or more output control signals, the internal circuit can be turned on / off without the need for dedicated external terminals (including IC pads). Therefore, the output voltage can be varied in stages using a small number of external terminals, enabling miniaturization of the package, and the internal circuit can be disconnected in standby mode, thereby reducing power consumption. Furthermore, a low-cost microcomputer without an internal D / A conversion circuit can be used as the power control device, and the output voltage switching and power on / off control can be performed through the microcomputer's I / O functions (general purpose ports).

[0024] Here, the voltage divider circuit described above consists of a first resistive element and a resistive circuit connected in series between the output terminal and the ground point.

[0025] The above-mentioned resistor circuit has a series-connected switching element and a resistive element.

[0026] The aforementioned switching element becomes either on or off based on signals or voltages from the aforementioned logic circuit.

[0027] In addition, the above-mentioned resistor circuit may also have multiple columns of series-connected switching elements and resistor elements, and the multiple switching elements are turned on or off by signals or voltages from the above-mentioned logic circuit.

[0028] Based on this structure, for example, when the output control signal input from the outside is 2 bits, the output voltage value of 3 stages can be freely set for output, and when the output control signal is 3 bits, the output voltage value of 7 stages can be freely set for output.

[0029] Alternatively, the voltage divider circuit described above can be composed of a first resistive element and a resistive circuit connected in series between the output terminal and the ground point.

[0030] The aforementioned resistor circuit includes multiple resistor elements connected in series and a switching element connected between the connection node of the multiple resistor elements and a ground point.

[0031] The aforementioned multiple resistive elements are composed of a series resistor circuit, which consists of unit resistors, each with a predetermined resistance value, connected in series.

[0032] The aforementioned switching element becomes either on or off based on signals or voltages from the aforementioned logic circuit.

[0033] In addition, the resistor circuit described above may also include multiple switching elements connected between the connection nodes of the multiple resistor elements and the ground point, and the multiple switching elements become on or off states by signals or voltages from the logic circuit described above.

[0034] According to this structure, when a series resistor circuit consisting of unit resistors with predetermined resistance values ​​connected in series is used as a voltage divider resistor element, the number of unit resistors used can be reduced, and the area occupied by the resistor circuit can be reduced.

[0035] Furthermore, preferably, the voltage divider circuit is composed of a first resistive element and a resistive circuit connected in series between the output terminal and the ground point.

[0036] The aforementioned resistor circuit comprises multiple resistor elements connected in series and multiple switching elements connected between the connection nodes of the multiple resistor elements and the ground point.

[0037] The aforementioned multiple resistive elements are composed of a series resistor circuit, which consists of unit resistors, each with a predetermined resistance value, connected in series.

[0038] The aforementioned multiple switching elements become either on or off based on signals or voltages from the aforementioned logic circuit.

[0039] According to this structure, the bias circuit can be disconnected by control based on the output of a logic circuit with simple logic functions, thereby switching to a low-power mode that stops the operation of the power control semiconductor device.

[0040] Furthermore, a variable output voltage power supply device is preferably configured, comprising: a power control semiconductor device having the structure described above; and a control device that outputs an output control signal input to the two or more external terminals described above.

[0041] The output voltage varies according to the output control signal input from the control device to the two or more external terminals.

[0042] According to the variable output voltage power supply device with this structure, the output voltage can be changed in stages by inputting multiple control signals from the outside, and the operation of the power supply control semiconductor device can be stopped. Furthermore, the variable output voltage control and the power supply device stop control can be performed through the I / O function of the microcomputer.

[0043] The effects of the invention

[0044] The power control semiconductor device and the variable output voltage power supply device according to the present invention can, through a small number of external terminals, cause the output voltage to change in stages by means of an external control signal, and can turn the output voltage on and off by means of an external control signal. Furthermore, according to the present invention, it has the following advantages: it enables the simple control of the output voltage and the on / off switching of the power control semiconductor device and the variable output voltage power supply device using a low-cost microcomputer without an internal D / A conversion circuit.

[0045] Explanation of reference numerals in the attached figures

[0046] 10 Regulator IC, 11 Error Amplifier, 12 Voltage Divider Circuit, 13 Reference Voltage Circuit, 14 Logic Circuit, 15 Bias Circuit, G1 Logic Gate, Q1 Voltage Control Transistor, Pa, Pb Control Input Terminals. Attached Figure Description

[0047] Figure 1 This is a circuit diagram illustrating one embodiment of a series regulator-type variable output voltage power supply device to which the present invention is applicable.

[0048] Figure 2 It is a waveform diagram showing the relationship between the control signals Va and Vb in the regulator of the implementation method and the output voltage Vout.

[0049] Figure 3 (A) is a logic structure diagram showing an example of the logic circuitry constituting the regulator IC in the implementation embodiment. Figure 3(B) is a circuit diagram representing a specific example of a logic circuit (excluding G1).

[0050] Figure 4 This is a circuit diagram representing a specific example of a logic gate (NOR gate G1) and a bias circuit that constitutes a logic circuit.

[0051] Figure 5 This is a block diagram illustrating a structural example of a power supply system consisting of a regulator according to an embodiment and a microstructure for controlling the regulator.

[0052] Figure 6 This is a circuit diagram illustrating a modified example of the regulator IC in the implementation method. Detailed Implementation

[0053] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0054] Figure 1 An embodiment of a series regulator is shown as an output voltage variable power supply device to which the present invention is applied. Additionally, in Figure 1 In the diagram, the portion circled in dashed line is formed as a semiconductor integrated circuit (regulator IC) 10 on a semiconductor chip such as single-crystal silicon, and functions as a variable output voltage power supply device. This variable output voltage power supply device outputs a stable DC voltage to a load such as a fan motor (not shown) by connecting a capacitor Co to the output terminal OUT of the regulator IC 10.

[0055] Furthermore, in the following description, an example of using a bipolar transistor as the transistor constituting regulator IC10 will be shown, but a MOS transistor can also be used.

[0056] like Figure 1 As shown, in the variable output voltage power supply device of this embodiment, a voltage control PNP bipolar transistor Q1 is connected between the voltage input terminal IN, where the DC input voltage Vin of the regulator IC10 is applied, and the output terminal OUT. Resistors R1 and R2, which constitute a voltage divider circuit 12 that divides the output voltage Vout, are connected in series between the output terminal OUT and the grounding line (grounding point) to which the grounding potential GND is applied.

[0057] The voltage at the connection node N1 between resistors R1 and R2 constituting the voltage divider circuit 12 is used as the feedback voltage VFB and is input to the non-inverting input terminal of the error amplifier 11, which is used as an error amplifier circuit to control the gate terminal of the voltage control transistor Q1. Furthermore, a reference voltage Vref from a reference voltage circuit 13 that generates a predetermined reference voltage Vref based on the input voltage Vin is applied to the inverting input terminal of the error amplifier 11. The error amplifier 11 generates a voltage corresponding to the potential difference between the output feedback voltage VFB and the reference voltage Vref and supplies it to the gate terminal of the voltage control transistor Q1 to control Q1 and control the output voltage Vout to the desired potential.

[0058] Furthermore, in the regulator IC10 of this embodiment, between the connection node N1 of the resistors R1 and R2 and the ground point, a series circuit consisting of resistor R3 and switch element SW1 (i.e., resistor R3-switch element SW1), a series circuit consisting of resistor R4 and switch element SW2 (i.e., resistor R4-switch element SW2), and a series circuit consisting of resistor R5 and switch element SW3 (i.e., resistor R5-switch element SW3) are connected in parallel. Here, the resistance values ​​of resistors R3, R4, and R5 are set to different values. Further, the regulator IC10 is provided with control input terminals Pa and Pb as external terminals, wherein the external terminals are used to input control signals Va and Vb supplied by a microcomputer (not shown), etc., and a logic circuit 14 is also provided for generating signals OCS1 to OCS3 to control the switch elements SW1 to SW3 based on the input control signals Va and Vb from the control input terminals Pa and Pb. Additionally, resistor R2 can be omitted.

[0059] Furthermore, in this embodiment, the regulator IC10 is provided with a bias circuit 15 for generating the operating current of the error amplifier 11 and the reference voltage circuit 13. The logic circuit 14 has the function of generating an ON / OFF signal for controlling the conduction and disconnection of the bias circuit 15 by taking the logical sum of the input control signals Va and Vb from the control input terminals Pa and Pb. When both input control signals Va and Vb are low, the output signal ON / OFF becomes high and the bias circuit 15 is disconnected. In addition, it is configured here that when either Va or Vb is high, the output signal ON / OFF of the logic circuit 14 becomes low and the bias circuit 15 is turned on.

[0060] Then, when the bias circuit 15 is disconnected by the output signal ON / OFF of the logic circuit 14, the supply of operating current to the error amplifier 11, the reference voltage circuit 13, and the logic circuit 14 stops, thus stopping the operation of these internal circuits.

[0061] In addition, in the regulator IC10 of the present embodiment, when any one of the switching elements SW1 to SW3 is selectively turned on by the control signals OCS1 to OCS3 output from the logic circuit 14, any one of the resistors R3 or R4, R5 is connected in parallel with the resistor R2 constituting the voltage dividing circuit 12, and a part of the current flowing through the resistor R2 flows through the resistor R3 or R4, R5. Therefore, the voltage division ratio of the output voltage Vout of the voltage dividing circuit 12 changes. Thereby, the base voltage of the voltage control transistor Q1 is controlled to change the output current.

[0062] As a result, the output voltage Vout output from the output terminal OUT of the regulator IC10 changes in three stages according to the input control signals Va, Vb of the control input terminals Pa, Pb. In addition, the voltage division ratio of the voltage dividing circuit 12 is changed by the conduction and disconnection of the switching elements SW1 to SW3, and the voltage control transistor Q1 is controlled so that the potential of the node N1 quickly becomes the same potential as the reference voltage Vref by the virtual short-circuit action of the error amplifier 11.

[0063] In Table 1 below, a truth table showing the relationship between the input control signals Va, Vb, the levels of the output voltage Vout, and the disconnection modes of the bias circuit 15 is shown, and a waveform diagram example of this truth table is shown in Figure 2 In.

[0064] Table 1

[0065] Va Vb Bias OCS1 OCS2 OCS3 Vout L L OFF - - - OFF L H ON H L L V1 H L ON L H L V2 H H ON L L H V3

[0066] As Figure 2 shown, in the regulator of the present embodiment, the output voltage Vout changes to three levels of V1, V2, V3 (V1 < V2 < V3) according to the combination of the levels of the input control signals Va, Vb.

[0067] In addition, in Figure 1In the circuit, three sets of resistor-switching element columns are connected in parallel with resistor R2: resistor R3-switching element SW1 column, resistor R4-switching element SW2 column, and resistor R5-switching element SW3 column. However, by setting two sets of resistor-switching element columns and controlling the output voltage Vout in three stages through control signals OCS1 to OCS3 output from logic circuit 14—specifically, turning on only SW1, turning on only SW2, and turning on both SW1 and SW2—it is possible to change the output voltage Vout in three stages. However, in this case, the output voltage Vout when SW1 and SW2 are on depends on the resistance values ​​of resistors R2 and R3 and cannot be freely set. As shown in the above embodiment, by setting three sets of resistor-switching element columns, it has the advantage that the voltage in all three stages can be freely set.

[0068] exist Figure 3 In (A), a logic structure diagram of logic circuit 14 for generating control signals OCS1 to OCS3 for switching elements SW1 to SW3 according to Table 1 is shown. Figure 3 In (B), a specific circuit example of the part of logic circuit 14 other than the NOR gate G1 is shown.

[0069] like Figure 3 As shown in (A), the logic circuit 14 consists of an NOR gate G1 that generates ON / OFF signals to turn on and off the bias circuit 15 by taking the logical sum of the input control signals Va and Vb; two inverter circuits INV1 and INV2 that generate signal control signals OCS1 and OCS2 by inverting the input control signals Va and Vb; inverter circuits INV3 and INV4 that invert the outputs of inverter circuits INV1 and INV2; and an AND gate G2 that takes the outputs of INV3 and INV4 as inputs.

[0070] like Figure 3 As shown in (B), the inverter circuits INV1 and INV2 consist of two series resistors that divide the input control signals Va and Vb, bipolar transistors Q11 and Q12 that receive the divided voltage at their base terminals, and constant current sources CC1 and CC2 connected in series with transistors Q11 and Q12. Furthermore, the inverter circuits INV3 and INV4 consist of bipolar transistors Q13 and Q14 that receive the collector voltages of transistors Q11 and Q12 at their base terminals, and constant current sources CC3 and CC4 connected in series with transistors Q13 and Q14.

[0071] Furthermore, AND gate G2 is composed of series-connected bipolar transistors Q15 and Q16 that receive the collector voltages of transistors Q13 and Q14 at their base terminals, a bipolar transistor Q17 that receives the collector voltage of transistor Q16 at its base terminal, and constant current sources CC5 and CC6 connected in series with transistors Q16 and Q17. The constant current sources CC1 to CC6 can be constructed from secondary-side transistors of a current mirror circuit, in which current flows through the primary side via bias circuit 15.

[0072] Figure 4 The diagram shows a specific circuit example of the bias circuit 15 and the logic gate (or NOT gate) G1 in the regulator IC10 of this embodiment.

[0073] like Figure 4 As shown, logic gate G1 consists of resistors R11 and R12 connected in series between the control input terminal Pa and the ground terminal GND, an NPN bipolar transistor Q2 whose base terminal is connected to the connection node of resistors R11 and R12, resistors R13 and R14 connected in series between the control input terminal Pb and the ground terminal GND, and an NPN bipolar transistor Q3 whose base terminal is connected to the connection node of resistors R13 and R14. The collector terminals of transistors Q2 and Q3 are coupled to each other, and their coupling point is the output node N2.

[0074] On the other hand, the bias circuit 15 consists of a resistor R15 connected in series between the voltage input terminal IN and the output node N2 of the logic gate G1, an NPN bipolar transistor Q4, a resistor R16 connected between the base terminal and the emitter terminal of the transistor Q4, and an NPN bipolar transistor Q5 whose base terminal is connected to the collector terminal of the transistor Q4 and whose emitter terminal is connected to the base terminal of the Q4.

[0075] A current source, such as a current mirror circuit (not shown), is connected to the collector terminal of transistor Q5. If the base-emitter voltage of Q4 is VF and the resistance of resistor R15 is R, then when either transistor Q2 or Q3 of logic gate G1 is turned on, the output of logic gate G1, i.e., the potential of node N2, becomes low. Collector current flows through Q4, and a current I, represented by I = VF / R, is drawn from the current source (the primary-side transistor of the current mirror circuit) connected to the collector terminal of Q5, thus activating the internal circuit. Then, when both transistors Q2 and Q3 of logic gate G1 are turned off, the output of logic gate G1, i.e., the potential of node N2, becomes high. Current no longer flows through transistor Q4, and the current I drawn from the current source connected to the collector terminal of Q5 becomes 0, thereby stopping the operation of the internal circuit.

[0076] Next, through Figure 5An example of the structure of a variable output voltage power supply device using the aforementioned regulator IC10 with control input terminals Pa and Pb and a general-purpose microcomputer will be described.

[0077] When the regulator IC10 and general-purpose microcomputer described in the above embodiment are used to construct a variable output voltage power supply device, such as Figure 5 As shown, the connection is made by outputting control signals Va and Vb from the I / O ports of the microcomputer 20 and inputting them to the terminals Pa and Pb of the regulator IC 10. By configuring a power supply device with this connection, such as... Figure 2 As shown, a variable output voltage power supply device is implemented, which enables the output voltage Vout to change in three stages according to the control signals Va and Vb input to the control input terminals Pa and Pb, and can stop the operation of the regulator IC10.

[0078] As described above, the regulator IC10 according to this embodiment can stop the operation of the IC without the need for an external terminal to stop its operation, just like the regulator IC described in Patent Document 2. Furthermore, a regulator IC capable of linearly changing the output voltage Vout requires an external input of a control voltage to the output control terminal. Generating such a control voltage requires a general-purpose microcomputer with a built-in D / A conversion circuit. However, when the output voltage Vout changes in three stages as shown in the regulator IC100 of the above embodiment, a control signal can be output using a general-purpose port. Therefore, a low-cost microcomputer without an internal D / A conversion circuit can be used as a general-purpose microcomputer.

[0079] Furthermore, although the output voltage Vout can be varied in three stages by setting two control input terminals Pa and Pb in the regulator IC 10 of the above embodiment, the number of control input terminals is not limited to two; three or four or more can also be set. Moreover, in the case of, for example, three control input terminals, when all three-bit control signals input to these input terminals are low, the regulator IC switches to a mode where operation is stopped. By configuring the logic circuit 14 and the voltage divider circuit 12 of the output voltage Vout to vary in seven stages according to other combinations, a controllable variable output voltage power supply device can be implemented using a microcomputer that does not have an internal D / A conversion circuit.

[0080] (Modified Example)

[0081] Next, use Figure 6 A variation of the regulator IC10 of the above embodiment will be described.

[0082] Figure 6In the modified example shown, resistors R6, R7, and R8 are connected in series with resistor R1, which forms the voltage divider circuit 12 connecting the output terminal OUT of the regulator IC10 in the above embodiment to the ground point. Furthermore, a switching element SW1 is provided between the connection node N3 of resistors R6 and R7 and the ground point, and a switching element SW2 is provided between the connection node N4 of resistors R7 and R8 and the ground point. Moreover, the switching elements SW1 and SW2 are controlled to turn on and off by inverting the output signals OCS1 and OCS2 of inverters INV1 and INV2, which invert the control signals Va and Vb input to the control input terminals Pa and Pb.

[0083] Therefore, by controlling SW1 to be on, SW2 to be on, or both SW1 and SW2 to be off according to the control signals Va and Vb, the output voltage Vout can change in three stages (V1, V2, V3). Specifically, V1 is represented by V1 = (R1 + R6) × Vref / R6, V2 is represented by V2 = (R1 + (R6 + R7)) × Vref / (R6 + R7), and V3 is represented by V3 = (R1 + (R6 + R7 + R8)) × Vref / (R6 + R7 + R8).

[0084] Furthermore, in Figure 6 In the modified regulator IC, resistors R6, R7, and R8 are each composed of a series resistor circuit with multiple unit resistors, for example, each with a resistance of 10kΩ, connected in series. Specifically, for example, when it is desired to set the resistance value of resistors R6 and R37 to 50kΩ, five unit resistors are connected in series each; when it is desired to set the resistance value of resistor R8 to 100kΩ, ten unit resistors are connected in series. That is, a total of 20 unit resistors are required.

[0085] In contrast, when omitted Figure 1 In the voltage divider circuit 12 of the embodiment, the regulator of resistor R2 selects 50kΩ, 100kΩ, and 200kΩ as the resistance values ​​of resistors R3, R4, and R5, so that the output voltage Vout changes in three stages (V1, V2, V3) in the same way as the above-described variant example. When using, for example, a unit resistor with a resistance value of 10kΩ to configure resistors R3, R4, and R5, a total of 35 unit resistors must be used, of which 5 are for R3, 10 for R4, and 20 for R5.

[0086] Therefore, in this modified example, when a series resistor circuit with multiple unit resistors connected in series is used as the resistor constituting the voltage divider circuit 12, it has the advantage of being able to significantly (about half) reduce the number of unit resistors constituting the series resistor circuit, i.e., the area occupied by the resistors.

[0087] The invention proposed by the inventors has been specifically described above based on the embodiments, but the invention is not limited to the above embodiments. For example, although the above embodiments used... Figure 4 The circuit shown is a bias circuit 15, but other circuit structures disclosed, such as those in Patent Document 2, can also be used.

[0088] Furthermore, although the above embodiments describe the application of the present invention to a series regulator-type variable output voltage power supply device, the present invention can also be used for a shunt regulator-type power supply device.

Claims

1. A power supply control semiconductor device comprising: a voltage control transistor connected between a voltage input terminal for inputting a direct current voltage and an output terminal; a control circuit for controlling the voltage control transistor based on a feedback voltage outputted from a divided voltage circuit which divides an output voltage of the output terminal; a bias circuit for generating an operating voltage of the control circuit based on the direct current voltage inputted to the voltage input terminal; and two or more external terminals for inputting an output control signal supplied from the outside for controlling the output voltage, The power supply control semiconductor device according to claim 1, wherein The control circuit comprises: an error amplifier which outputs a voltage corresponding to a potential difference between the feedback voltage and a predetermined reference voltage; and a logic circuit, The logic circuit is inputted with two or more external input signals of high level or low level from the two or more external terminals, and comprises two or more transistors which are turned on and off by the two or more external input signals, and two or more current sources connected in series to each of the transistors, generates and outputs two or more control signals which shift the feedback voltage based on the two or more external input signals, generates and outputs a signal which makes the bias circuit in an inactive state based on any one of a plurality of combinations of the external input signals, and when the bias circuit is made in the inactive state based on the signal from the logic circuit, the currents of the two or more current sources are cut off.

2. The power supply control semiconductor device according to claim 1, wherein The divided voltage circuit is composed of a first resistance element and a resistance circuit connected in series between the output terminal and a ground, The resistance circuit has a switching element and a resistance element connected in series, The switching element is configured to be turned on or off by the signal from the logic circuit.

3. The power supply control semiconductor device according to claim 2, wherein The resistance circuit has a plurality of rows of switching elements and resistance elements connected in series, The plurality of switching elements are configured to be turned on or off by the signal from the logic circuit.

4. The power supply control semiconductor device according to claim 1, wherein The divided voltage circuit is composed of a first resistance element and a resistance circuit connected in series between the output terminal and a ground, The resistance circuit comprises a plurality of resistance elements connected in series and a switching element connected between a connection node of the plurality of resistance elements and a ground, The plurality of resistance elements are composed of a series resistance circuit in which unit resistances each having a predetermined resistance value are connected in series, The switching element is configured to be turned on or off by the signal from the logic circuit.

5. The power supply control semiconductor device according to claim 4, wherein The resistance circuit comprises a plurality of switching elements connected between the connection node of the plurality of resistance elements and the ground, The plurality of switching elements are configured to be turned on or off by the signal from the logic circuit.

6. An output-voltage-variable power supply device characterized by comprising: comprises: The semiconductor device according to any one of claims 1 to 5; and a control device that outputs the two or more external input signals input to the two or more external terminals, wherein the output voltage varies in accordance with the two or more external input signals input from the control device to the two or more external terminals.

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