Power supply control semiconductor device, output voltage variable power supply device, and design method

Abstract

The present application provides a kind of power supply control semiconductor device and output voltage variable power supply device and design method.Voltage control semiconductor device has: the 1st error amplifier (11) of the voltage corresponding to the potential difference between the voltage after the output voltage is divided and the reference voltage, control circuit is changed by the output voltage input to the 1st error amplifier is offset according to the voltage of external terminal to change output voltage, the series connection form of the 1st resistance and the 2nd resistance connected with output terminal and constituting the voltage division circuit for dividing output voltage is formed in the common 1st island region, and output voltage is applied to the 1st island region as island suspension potential, the 3rd resistance and the 4th resistance connected in series with the transistor driven by the 2nd error amplifier (13) with the voltage of external terminal as input are formed in the common 2nd island region, and the voltage of the connection node of the transistor and the 3rd resistance is applied to the 2nd island region as island suspension potential.

Description

TECHNICAL FIELD

[0001] The present application relates to a power supply control semiconductor device of a series regulator system capable of linearly changing an output voltage by a control signal, a power supply device, and a design method of the power supply control semiconductor device. BACKGROUND

[0002] As a power supply device that outputs a desired potential of a direct current voltage by controlling a transistor provided between a direct current voltage input terminal and an output terminal, there is a series regulator (hereinafter, abbreviated as a regulator). As an application of the regulator, there is, for example, a constant voltage power supply device (a regulator for vehicle) for supplying a direct current power to an in-vehicle electronic device such as a blower device (fan) mounted on a vehicle body, a lighting device, an audio device, and the like.

[0003] In the electronic device such as the blower device (fan) and the lighting device, sometimes, it is desired to add a function of being able to continuously change a blower amount and a brightness of lighting by linearly changing a voltage for driving a motor that rotates the fan and a lamp of the lighting device, and thus, there is a demand for the regulator to have a function of linearly changing an output voltage.

[0004] Conventionally, as an invention related to a regulator capable of changing an output voltage, there are, for example, inventions described in Patent Literature 1 and Patent Literature 2.

[0005] However, in the regulator described in Patent Literature 1, by switching a division ratio of a voltage dividing circuit that divides an output voltage to generate a feedback signal, it is possible to switch the output voltage in stages, but there is a problem that it is not possible to linearly change the output voltage. In addition, although it is also possible to consider to approximately linearly change by increasing the number of series resistors and switching transistors that constitute the voltage dividing circuit, if so, there is a problem that the number of components increases and the mounting area becomes large, and it is difficult to realize a small size of the device.

[0006] In addition, in the variable output voltage regulator described in Patent Literature 2, although it is possible to linearly change the output voltage, since an adjustment circuit of an output voltage value is constituted by external components of a regulator IC, the number of components is large, the mounting area is large, and thus, the miniaturization of the device is hindered, and the power consumption is increased. In addition, there is a problem that the output voltage deviates and the accuracy of the output voltage deteriorates due to a deviation in resistance values of adjustment resistive elements used.

[0007] Therefore, the present applicant made an invention of a power supply control semiconductor device and an output voltage variable power supply device that does not cause an increase in the number of components and the number of components and is capable of linearly changing an output voltage, and made a prior application (Japanese Patent Application No. 2018-247303). Figure 6A circuit diagram of one embodiment of a semiconductor device for power supply control relating to the application of the prior application is shown. Furthermore, in Figure 6 The range enclosed by the dotted line 10 in FIG. 1 is a circuit formed on a semiconductor substrate.

[0008] However, in a semiconductor integrated circuit (IC), a diffusion resistance composed of a diffusion layer of a predetermined impurity concentration formed in an island region surrounded by an insulator is generally used as a resistance element constituting a circuit. Moreover, in an IC in which such a diffusion resistance is formed, in order to prevent an undesired current from flowing through a parasitic element (PN junction), the following design is performed: for example, when the island region is an N-type region and the diffusion resistance is a P-type region, a potential (island floating potential) such as a power supply voltage higher than a voltage applied to the P-type diffusion resistance is applied to the island region, so that a PN junction between the diffusion resistance and the island region is always in a reverse bias state.

[0009] In Figure 6 the IC for power supply control shown in FIG. 1, when the resistors Rl, R2 constituting a circuit for dividing an output voltage and a resistor R4 on the output side of an error amplifier 13 to which an output control signal Vadj is input are formed as P-type diffusion resistors, since the island regions of these diffusion resistors are formed as N-type regions, a general design method is to apply the output voltage Vout as the island floating potential of the resistors Rl, R2. On the other hand, since the island region of the resistor R4 is apart from an output terminal (output pad), it is considered to select the emitter potential (source potential when Q2 is a MOSFET) of a transistor Q2 having a relatively high potential in the vicinity of the island region of the resistor R4 as the island floating potential to be applied.

[0010] However, it is known that a diffusion resistance formed on a semiconductor substrate has a bias dependency as follows: once the island floating potential is varied, the thickness of a depletion layer generated between the diffusion layer as a resistor and the semiconductor region of the island region is varied, and in correspondence therewith, the resistance value is varied.

[0011] Specifically, in Figure 6 the IC for power supply control shown in FIG. 1, by the setting of the resistors, the output voltage Vout can be variably controlled in the range of Vref to Vin. Therefore, if the output voltage Vout is selected as the island floating potential of the resistors Rl, R2, and the emitter potential of the transistor Q2 is selected as the island floating potential of the resistor R4, Vout varies in the range of 3.0 V to 7.4 V, for example, in accordance with the set values of the resistors Rl, R2, R4.

[0012] On the other hand, in most cases, the control signal Vadj is designed to vary in a range from 0 V to 3.3 V which is the power supply voltage of a control device such as a microcomputer that generates Vadj. In this case, the island floating potential of the resistor R4 varies in a range from 0 V to 3.3 V which is the same range as that of the control signal Vadj. That is, the variation range of the island floating potential of the resistor R4 is 3.3 V which is smaller than the variation range 4.4 V of the island floating potentials of the resistors Rl, R2, and there is a difference of 1.1 V between the variation ranges of the above two island floating potentials. As a result, the variation of the resistance value due to the bias voltage dependency of the resistors Rl, R2 and the resistor R4 appears as a difference of a degree that cannot be ignored, and thus there is a problem in that the linearity of the variation of the output voltage Vout with respect to the variation of the control signal Vadj is reduced.

[0013] In addition, it is considered at first glance that in the power supply control IC shown in Figure 6 However, if the circuit is configured in such a manner that the output voltage Vout is applied to the island region of the resistor R4, there is a possibility that when an accident of short-circuiting the output terminal to the ground potential occurs, 0 V is applied to the island region of the resistor R4, and a forward voltage is applied to the PN junction of the diffusion resistor, thereby causing an undesirable current to flow. In addition, when the control signal Vadj is input first and then the input voltage Vin is turned on, during a period until the output voltage Vout reaches the target potential, a forward voltage is applied to the PN junction of the diffusion resistor R4, and thus the above-described configuration is not adopted.

[0014] In addition, although it is also possible to consider that the input voltage Vin is selected as the island floating potential of the resistor R4, if the circuit is configured in such a manner that the input voltage Vin is applied to the island region of the resistor R4, when used in a system in which the input voltage Vin is unstable, the resistance value varies depending on the variation of the input voltage, and thus the above-described configuration cannot be adopted when such a use is considered.

[0015] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 11-265224

[0016] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2010-055490 SUMMARY

[0017] The present application has been made in view of the above-described problems, and has an object to provide a power supply control semiconductor device capable of reducing the difference in bias voltage dependency that occurs between a plurality of resistance elements configuring a circuit without causing any malfunction in the operation of the circuit, thereby improving the linearity of the variation of an output voltage with respect to the variation of a control signal, and an output voltage variable power supply device using the power supply control semiconductor device.

[0018] To achieve the above object, a semiconductor device for power control includes a voltage control transistor connected between a voltage input terminal to which a DC voltage is input and an output terminal, a control circuit for controlling the voltage control transistor in accordance with a feedback voltage output, and an external terminal for controlling an output voltage from the outside, wherein the control circuit includes a first voltage dividing circuit having a first resistor element and a second resistor element connected in series to the output terminal and dividing the output voltage of the output terminal, a first error amplifier outputting a voltage corresponding to a potential difference between the voltage divided by the first voltage dividing circuit and a predetermined reference voltage, and an output voltage changing circuit shifting the divided voltage based on the first voltage dividing circuit input to the first error amplifier in accordance with a voltage input to the external terminal, thereby changing the output voltage in accordance with the voltage of the external terminal, the output voltage changing circuit including a second error amplifier inputting the voltage of the external terminal, a second transistor to which an output of the second error amplifier is applied to a control terminal, and a third resistor element and a fourth resistor element connected in series to the second transistor, a voltage of a connection node of the third resistor element and the fourth resistor element being fed back to an input terminal of the second error amplifier.

[0019] According to the semiconductor device for power control having the above structure, the output voltage can be linearly changed by an output control signal (Vadj) from the outside.

[0020] Here, preferably, the first resistor element and the second resistor element are composed of diffusion layers formed on a common first island region, the output voltage is applied to the first island region as an island floating potential, the third resistor element and the fourth resistor element are composed of diffusion layers formed on a common second island region, and a voltage of a connection node of the second transistor and the third resistor element is applied to the second island region as an island floating potential.

[0021] According to the above structure, the difference between the variation range of the island floating potential of the diffusion resistance islands of the first resistor element (R1) and the second resistor element (R2) and the variation range of the island floating potential of the diffusion resistance islands of the third resistor element (R3) and the fourth resistor element (R4) can be reduced in accordance with the variation of the output control signal, and thus the linearity of the variation of the output voltage with respect to the variation of the output control signal can be improved.

[0022] In addition, by adding only one resistance element, an island floating potential for a diffusion resistance formation island suitable for improving linearity (straight linearity) of variable characteristics of the output voltage can be generated, and by changing only the resistance value of the added resistance element, the bias dependency of the diffusion resistance can be arbitrarily and easily corrected. Furthermore, even if an accident of short-circuiting of the output terminal to the ground or a variation in the input voltage occurs, the island floating potential of the diffusion resistance formation island of the third and fourth resistance elements is not affected, and thus the operation of the circuit is not malfunctioned.

[0023] In addition, preferably, the output voltage changing circuit includes a first current mirror circuit connected to the voltage input terminal and copying a current flowing in the second transistor, and a second current mirror circuit connected to the voltage input terminal and causing the current flowing in the first current mirror circuit to flow in a return direction, and the current copied by the second current mirror circuit is extracted from a node at which the voltage divided by the first voltage dividing circuit is extracted.

[0024] According to such a configuration, while improving linearity of a variation in the output voltage with respect to a variation in the output control signal, not only the variable range of the output voltage can be changed by the resistance value of the resistance element configuring the output voltage changing circuit, but also the variable range of the output voltage can be changed by the current ratio of the current mirror circuit, and thus the degree of freedom in design is improved.

[0025] In addition, preferably, the output voltage changing circuit includes a second voltage dividing circuit having a fifth resistance element and a sixth resistance element connected in series to the external terminal and dividing a voltage input to the external terminal, and the voltage divided by the second voltage dividing circuit is supplied to the second error amplifier.

[0026] According to the above configuration, the output voltage can be linearly varied by the voltage (output control signal Vadj) input to the external terminal, and by dividing the output control signal Vadj and inputting it to the error amplifier, the input range of the output control signal Vadj can be expanded.

[0027] In addition, as another invention related to the present application, when designing the power supply control semiconductor device having the above configuration, the resistance value of the third resistance element is designed in such a manner that the difference between the variation range of the island floating potential applied to the second island region and the variation range of the output voltage varied in accordance with the voltage of the external terminal is small.

[0028] According to such a design method, the design of the circuit constant for improving linearity (straight linearity) of variable characteristics of the output voltage can be easily performed.

[0029] In addition, preferably, the resistance value of the first resistance element is set to Rl, the resistance value of the second resistance element is set to R2, the resistance value of the third resistance element is set to R3, and the resistance value of the fourth resistance element is set to R4, in which case, the resistance value Rl of the first resistance element, the resistance value R2 of the second resistance element, and the resistance value R4 of the fourth resistance element are determined assuming that the third resistance element is not present, and then the resistance value R3 of the third resistance element is determined so as to satisfy the following mathematical expression: R3 = Rl - R4.

[0030] According to such a design method, the resistance value of the third resistance element appropriate for reducing the difference between the variation range of the island floating potential applied to the second island region and the variation range of the output voltage that varies in accordance with the voltage of the external terminal (ADJ or PI) can be easily calculated.

[0031] According to the power supply control semiconductor device and the output voltage variable power supply device according to the present application, the following effects are obtained: the difference in bias voltage dependency between the plurality of resistance elements constituting the circuit can be reduced without causing any malfunction in the operation of the circuit, and thus the linearity of the change in the output voltage with respect to the change in the control signal is improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a circuit configuration diagram showing a first embodiment of a power supply control semiconductor device and an output voltage variable power supply device of a series regulator system to which the present application is applied.

[0033] Figure 2 is a waveform diagram showing the relationship between the switching control signal ON / OFF and the output control signal Vadj and the output voltage Vout in the regulator of the first embodiment.

[0034] Figure 3 is a graph showing the relationship between the output control signal Vadj and the inclination (output voltage variable coefficient) of the output voltage variation range in the regulator of the first embodiment.

[0035] Figure 4 is a circuit configuration diagram showing a modified example of the output voltage variable power supply device of the first embodiment.

[0036] Figure 5 is a circuit configuration diagram showing a second embodiment of an output voltage variable power supply device to which the present application is applied.

[0037] Figure 6 is a circuit configuration diagram showing an embodiment of an output voltage variable power supply device of a prior application.

[0038] REFERENCE NUMERALS

[0039] 10... regulator IC, 11... 1st error amplifier, 12... 1st voltage dividing circuit, 13... 2nd error amplifier, 14A, 14B... current mirror circuit, 15... reference voltage source, 16... bias circuit, 17a, 17b... island region (resistance island formed by diffusion layer), 18... 2nd voltage dividing circuit, Q1... voltage control transistor, ADJ... output control terminal, CNT... switch control terminal. DETAILED DESCRIPTION

[0040] Hereinafter, a preferred embodiment of the present application will be described based on the drawings.

[0041] (1st Embodiment)

[0042] Figure 1 A 1st embodiment of a series regulator as an output voltage variable power supply device to which the present application is applied is shown. Further, in Figure 1 , a portion enclosed by a dotted line is formed as a semiconductor integrated circuit (regulator IC) 10 on a semiconductor chip such as a single crystal silicon, and by connecting a capacitor Co as an external element to an output terminal OUT of the regulator IC 10, functions as an output voltage variable power supply device which outputs a stable direct current voltage to a load such as a motor or an LED lamp, not shown.

[0043] In the output voltage variable power supply device of the present embodiment, as shown in Figure 1 , between a voltage input terminal IN of the regulator IC 10 to which a direct current input voltage Vin is applied and an output terminal OUT, a PNP bipolar transistor for voltage control (hereinafter referred to as voltage control transistor) Q1 is connected, and between the output terminal OUT and a ground line (ground point) to which a ground potential GND is applied, resistors R1 and R2 which constitute a voltage dividing circuit 12 for dividing the output voltage Vout are connected in series.

[0044] The voltage of a connection node N1 of the resistors R1 and R2 which constitute the voltage dividing circuit 12 is inputted as a feedback voltage VFB to a non-inverting input terminal of an error amplifier 11 which is an error amplifying circuit for controlling a gate terminal of the voltage control transistor Q1. Further, the error amplifier 11 generates a voltage corresponding to a potential difference between the output feedback voltage VFB and a predetermined reference voltage Vref and supplies it to a base terminal of the voltage control transistor Q1 to control Q1, and controls so that the output voltage Vout becomes a desired potential.

[0045] In addition, in the regulator IC 10 of the present embodiment, an output control terminal ADJ, which is an external terminal of an input signal Vadj for controlling an output voltage Vout supplied from a microcomputer or the like not shown, is provided, and a second error amplifier 13 to which the output control signal Vadj applied to the terminal ADJ is input as a non-inverting input terminal, and an NPN bipolar transistor Q2 having a base terminal connected to an output terminal of the error amplifier 13, a resistance R3 and a resistance R4 connected in series between an emitter terminal of the transistor Q2 and a ground terminal are provided.

[0046] In the error amplifier 13, a negative feedback is applied by inputting the voltage V2 of the connection node N2 of the resistance R3 and the resistance R4 to an inverting input terminal thereof, and the transistor Q2 is driven in a manner that the transistor Q2 is virtually short-circuited to flow a current in the resistance R3 and the resistance R4 to make the voltage V2 of the connection node N2 the same as the voltage Vadj of the non-inverting input terminal.

[0047] Further, in the regulator IC 10, a first current mirror circuit 14A constituted by PNP bipolar transistors Trl and Tr2 having base terminals mutually coupled to each other and emitter terminals connected to an input terminal IN, and a second current mirror circuit 14B constituted by NPN bipolar transistors Tr3 and Tr4 having base terminals mutually coupled to each other and emitter terminals connected to a ground terminal are provided.

[0048] The transistors Trl and Tr3 are coupled by base terminals and collector terminals to function as current-voltage conversion elements, and the converted voltages are applied to the transistors Tr2 and Tr4, respectively, so that currents corresponding to the emitter size ratios of the transistors Trl and Tr2 and the transistors Tr3 and Tr4 flow into the transistors Tr2 and Tr4, respectively.

[0049] Further, the transistor Q2 driven by the error amplifier 13 and the resistances R3 and R4 are connected in series to the transistor Trl of the first current mirror circuit 14A, the collector terminal of the transistor Tr4 of the second current mirror circuit 14B is connected to the connection node Nl of the resistances Rl and R2 constituting the voltage dividing circuit 12, and a feedback voltage VFB, which is offset by drawing a current corresponding to the potential of the output control signal Vadj from the connection node Nl, is input to the non-inverting input terminal of the error amplifier 11 for controlling the base terminal of the voltage control transistor Ql.

[0050] Thus, the output terminal OUT of the regulator IC 10 outputs an output voltage Vout corresponding to the output control signal Vadj. Therefore, the error amplifier 13 and the transistor Q2 and the resistors R3, R4 and the current mirror circuits 14A, 14B constitute an output voltage changing circuit for changing the output voltage Vout to a voltage corresponding to the output control signal Vadj.

[0051] Further, in the regulator IC 10 of the present embodiment, a reference voltage source 15 that generates a reference voltage Vref based on the input voltage Vin and a bias circuit 16 that generates an operating current of the error amplifier 11 are provided, and a switching control terminal CNT that is an external terminal that inputs a signal ON / OFF for switching control of the bias circuit 16 is provided, and if a switching control signal ON / OFF of a low level (0 V) is input to the switching control terminal CNT, the bias circuit 16 stops supplying the operating current to the reference voltage source 15 and the error amplifier 11, and stops the operation of these circuits.

[0052] In addition, in the regulator IC 10 of the present embodiment, the resistors R1, R2 that constitute the voltage dividing circuit 12 are formed as diffusion resistors in a common island region 17a obtained by surrounding the periphery with an insulator in the surface of the semiconductor substrate, and a wiring is formed on the island region 17a to apply the voltage Vout of the output terminal OUT thereto.

[0053] On the other hand, the resistors R3, R4 connected in series between the emitter terminal of the transistor Q2 and the ground are also formed as diffusion resistors in a common island region 17b obtained by surrounding the periphery with an insulator in the surface of the semiconductor substrate, and a wiring is formed on the island region 17b to apply the voltage V3 of the connection node N3 of the emitter terminal of Q2 and the resistor R3 thereto.

[0054] As the diffusion resistors formed in the island regions 17a, 17b surrounded with an insulator, diffusion resistors having the same structure as a general diffusion resistor formed by a known bipolar semiconductor process can be used, for example. Specifically, an element having a structure in which a buried layer is formed under an island region obtained by separating the element by trench isolation, a diffusion layer is formed on the surface of the island region above the buried layer, and electrodes are formed at both ends of the diffusion layer can be used.

[0055] In the output voltage variable power supply device of the present embodiment, in the case where the current ratios of the current mirror circuits 14A and 14B are set to 1:1, respectively, the output voltage Vout is represented by the following mathematical expression (1):

[0056] Vout = ((R2+R1) / R2)*Vref + (Vadj / R4)*R1... (1)

[0057] Therefore, in the output voltage variable power supply device of the present embodiment, by applying an arbitrary voltage (control signal Vadj) to the output control terminal ADJ, an arbitrary output voltage can be set, and the output voltage Vout can be linearly changed according to the applied voltage of the output control terminal ADJ.

[0058] Specifically, if the relationship between the input signal ON / OFF input to the switch control terminal CNT, the control signal Vadj input to the output control terminal ADJ, and the output voltage Vout in the output voltage variable power supply device of the present embodiment is represented, it is as shown in Figure 2

[0059] According to Figure 2 it is known that if the control signal Vadj is changed in the range of, for example, 0 to 3.3 V, the output voltage Vout can be changed in the range of Vref to Vin. Furthermore, the variable range 0 to 3.3 V of the control signal Vadj is one example, and is not limited thereto.

[0060] In the above mathematical expression (1) representing the output voltage Vout, the variation range of the output voltage based on the control signal Vadj is represented by (Vadj / R4)*R1 of the 2nd term on the right side. On the other hand, the voltage V3 of the node N3 is represented by the following mathematical expression (2):

[0061] V3 = Vadj * (1 + R3 / R4)... (2)

[0062] Therefore, by setting the value of the resistance R3 so that the 2nd term of the mathematical expression (1) = the mathematical expression (2), the degree of influence of the bias dependency of the resistance values due to the island floating potential on the resistances R1, R2 and the resistances R3, R4 can be made uniform, and thus the decrease in the relative accuracy of the resistance values of the resistances R3, R4 with respect to the resistance values of the resistances R1, R2 which change with the variation of the control signal Vadj can be suppressed.

[0063] Specifically, by setting to the 2nd term of the mathematical expression (1) = the mathematical expression (2), the following mathematical expression (3) can be obtained: (Vadj / R4)*R1 = Vadj*(1 + R3 / R4)... (3), and by arranging this equation, it becomes the following mathematical expression (4): R3 = R1 - R4... (4). Therefore, by setting the resistance value of R3 so as to satisfy the mathematical expression (4), the decrease in the relative accuracy of the resistance values of the resistances R3, R4 with respect to the change in the resistance values of the resistances R1, R2 which occur with the change of the island floating potential can be suppressed.

[0064] ​Here, if the output when Vadj = 0 V is set as Vout, and the output when Vadj is applied is set as Vout', it can be expressed as Vout' = Vout + (Vadj x variable coefficient). Here, the variable coefficient is the inclination of the output voltage variation range. In Figure 3 , the variable coefficient of the control signal Vadj when the resistance R3 is provided and the resistance value of R3 is set to satisfy the mathematical expression (4) is plotted with a dotted line A. For the sake of comparison, the relationship between the control signal Vadj and the output voltage variable coefficient in the circuit in which the resistance R3 is not provided (see Figure 6 ) is indicated with a broken line B. Further, the solid line C indicates the ideal characteristic of the output voltage variable coefficient with respect to the control signal Vadj.

[0065] As is apparent from Figure 3 , by setting the value of the resistance R3 to satisfy the mathematical expression (4) and applying the voltage V3 of the connection node N3 of the emitter of the transistor Q2 and the resistance R3 to the common island region 17b of the resistances R3 and R4, the variation of the output voltage variable coefficient with respect to the variation of the control signal Vadj can be reduced. Thereby, the linearity of the variation of the output voltage Vout can be improved.

[0066] Further, in the present embodiment, since not only the variable range of the output voltage Vout can be changed by the value of the resistance R4, but also the variable range of the output voltage Vout can be changed by the current ratio of the current mirror circuits 14A and 14B, it has the advantage that the degree of freedom of design is improved. Furthermore, since it is a structure in which the output voltage can be linearly varied by the output control signal Vadj from the outside, and the output voltage Vout is varied by causing the current after the voltage-current conversion by the error amplifier 13 to flow through the resistance Rl, it can realize an output voltage variable power supply device which is less affected by power supply noise.

[0067] (Modified Example)

[0068] Figure 4 A modified example of the output voltage variable power supply device of the first embodiment shown in Figure 1 will be shown in the following. In the modified example, between the output control terminal ADJ which inputs the output control signal Vadj supplied from a microcomputer or the like and the ground, a voltage dividing circuit 18 composed of resistances R5, R6 in a series form is provided which divides the output control signal Vadj. Further, the resistances R5, R6 which constitute the voltage dividing circuit 18 are also formed as diffusion layers in a common island region 17c, and the voltage Vadj of the external terminal ADJ is applied as an island floating potential to the island region 17c. Thereby, as in the above first embodiment, the decrease in the relative accuracy of the resistance values of R5, R6 caused by bias dependence can be suppressed.

[0069] In addition, in Figure 1 In the regulator IC of the embodiment, although the error amplifier 13 is made to have a gain by providing the resistor R3, as shown in a modification example of the embodiment, by providing the voltage dividing circuit 18 to divide the output control signal Vadj and input it to the error amplifier 13, the gain of the error amplifier 13 is adjusted by the resistor R3 to make the variation range of the island floating potential of the island regions 17a and 17b uniform, and the decrease in the relative accuracy of the resistance values of R3 and R4 with respect to the change in the resistance values of Rl and R2 that occurs with the change in the island floating potential can be suppressed. Further, by dividing the output control signal Vadj and inputting it to the error amplifier 13, the input range of Vadj can be expanded. Figure 4

[0070] Further, Figure 1 and Figure 4 The current mirror circuits 14A and 14B in the embodiments are not limited to the illustrated structure, and can be other circuit forms such as a Wilson type, a base current compensation type, and the like.

[0071] (Second Embodiment)

[0072] Figure 5 A second embodiment of a series regulator that is an output voltage variable power supply device to which the present application is applied is described.

[0073] In the output voltage variable power supply device of the embodiment, between the voltage input terminal IN and the output terminal OUT of the regulator IC 10 to which a direct current voltage Vin is applied, a voltage control transistor Ql constituted by a PNP bipolar transistor is connected, and between the output terminal OUT and a ground line to which a ground potential GND is applied, the resistors R0, Rl, and R2 that constitute a voltage dividing circuit 12 for dividing an output voltage Vout are connected in series.

[0074] The voltage of the connection node Nl of the resistors Rl and R2 that constitute the voltage dividing circuit 12 is input to the non-inverting input terminal of the error amplifier 11 as a feedback voltage VFB, and the error amplifier 11 is an error amplifier that is an error amplifying circuit for controlling the base terminal of the voltage control transistor Ql. Further, the error amplifier 11 generates a voltage corresponding to the potential difference between the output feedback voltage VFB and a predetermined reference voltage Vref and supplies it to the base terminal of the voltage control transistor Ql to control Ql, and controls so that the output voltage Vout becomes a desired potential.

[0075] ​In addition, in the regulator IC 10 of the present embodiment, a bipolar transistor Q3 connected in parallel with the above-mentioned voltage control transistor Ql and constituting a current mirror circuit with Ql is provided, and the same voltage as that applied to the base terminal of the voltage control transistor Ql is applied to the base terminal of the transistor Q3 as a control terminal thereof. Thus, assuming that the current mirror ratio of the transistors Ql and Q3 is n, a current proportional to the collector current of Ql (a current of 1 / n) flows through Q3.

[0076] In addition, in the regulator IC 10, an external terminal Pl for connecting a resistance R8 for converting the collector current of Q3 into a voltage is provided in series with the above-mentioned current mirror transistor Q3 between the voltage input terminal IN and the ground potential point outside the chip.

[0077] Further, in the regulator IC 10, an error amplifier 13 having the in-phase input terminal connected to the above-mentioned external terminal Pl is provided, and an NPN bipolar transistor Q2 and resistances R3 and R4 are connected in series between the connection node NO of the resistances R0 and Rl constituting the above-mentioned voltage dividing circuit 12 and the ground point inside the chip.

[0078] Further, the base terminal of the above-mentioned transistor Q2 is connected to the output terminal of the above-mentioned error amplifier 13, and the connection node N2 of the resistances R3 and R4 is connected to the inverting input terminal of the error amplifier 13. Thus, the error amplifier 13 operates the transistor Q2 so that the voltage V2 of the connection node N2 becomes equal to the input voltage of the in-phase input terminal (the potential of the external terminal Pl). Here, the resistance R8 connected to the external terminal Pl is constituted by a variable resistance, and the output voltage Vout can be varied by varying the resistance value of the resistance R8.

[0079] The current Iout' proportional to the collector current of the voltage control transistor Ql, i.e., the current Iout output from the output terminal OUT, flows through the current mirror transistor Q3, and the current is converted into a voltage by the external resistance R8 and input to the in-phase input terminal of the error amplifier 13. Thus, the current Iout" proportional to the output current Iout flows through the transistor Q2, and the current Iout" is led out from the resistance R0 constituting the voltage dividing circuit 12. Thus, the potential of the in-phase input terminal of the error amplifier 11 varies depending on the resistance value of the external resistance R8, the control voltage of the voltage control transistor Ql of the error amplifier 11 varies, and the output voltage Vout varies.

[0080] In the present embodiment, the output voltage Vout is applied as the island floating potential to the common island region 17a of the resistors R0, R1 and R2, and the voltage V3 of the emitter terminal of the transistor Q2 and the connection node N3 of the resistor R3 is applied as the island floating potential to the common island region 17b of the resistors R3 and R4. Thus, the degree of influence of the bias dependence of the resistance values due to the island floating potential on the resistors R0, R1, R2 and the resistors R3, R4 is made uniform, and thus the decrease in the relative accuracy of the resistance values of R3, R4 with respect to the resistance values of R1, R2 due to the change in the island floating potential is suppressed.

[0081] The above has described the application made by the present inventors based on the embodiments, but the present application is not limited to the above-described embodiments. For example, although the switch control terminal CNT that inputs an ON / OFF signal for stopping the operation of the IC is provided in the regulator IC 10 of the above-described first embodiment, the structure in which this switch control terminal CNT is omitted can also be used. In the case where the switch control terminal CNT is omitted, the regulator IC 10 can be constituted with 4 terminals, and thus the space saving and the cost reduction due to the miniaturization of the package can be achieved.

[0082] In addition, although the regulator IC 10 is constituted by a bipolar transistor in the above-described first and second embodiments, it can also be constituted by a MOS transistor (P-MOS and N-MOS).

[0083] Further, although the application of the present application to the output voltage variable power supply device of the series regulator system is described in the above-described embodiments, the present application can also be applied to the power supply device of the parallel regulator system.

Claims

1. A semiconductor device for power supply control, comprising: a voltage control transistor connected between a voltage input terminal to which a direct current voltage is input and an output terminal, a control circuit for controlling the voltage control transistor in accordance with a feedback voltage output, and an external terminal for controlling an output voltage from the outside, characterized in that the control circuit comprises: a first voltage dividing circuit having a first resistor element and a second resistor element connected in series to the output terminal and dividing the output voltage of the output terminal; a first error amplifier supplying a voltage corresponding to a potential difference between the voltage divided by the first voltage dividing circuit and a predetermined reference voltage to a control terminal of the voltage control transistor; and an output voltage changing circuit shifting the divided voltage obtained by the first voltage dividing circuit input to the first error amplifier in accordance with a voltage input to the external terminal, thereby changing the output voltage in accordance with the voltage of the external terminal, the output voltage changing circuit comprises: a second error amplifier inputting the voltage of the external terminal; a second transistor to which the output of the second error amplifier is applied to a control terminal; and a third resistor element and a fourth resistor element connected in series to the second transistor, a voltage of a connection node of the third resistor element and the fourth resistor element is fed back to an input terminal of the second error amplifier, the third resistor element and the fourth resistor element are composed of diffusion layers formed on a common first island region, a voltage of a connection node of the second transistor and the third resistor element is applied to the first island region as an island floating potential, in a case where a resistance value of the first resistor element is set to Rl, a resistance value of the second resistor element is set to R2, a resistance value of the third resistor element is set to R3, and a resistance value of the fourth resistor element is set to R4, a resistance value Rl of the first resistor element, a resistance value R2 of the second resistor element, and a resistance value R4 of the fourth resistor element are set in accordance with a set voltage of the output voltage of the output terminal, and a resistance value R3 of the third resistor element is determined so as to satisfy the following mathematical expression: R3 = Rl - R4.

2. The semiconductor device for power supply control according to claim 1, characterized in that the first resistor element and the second resistor element are composed of diffusion layers formed on a common second island region, and the output voltage is applied to the second island region as an island floating potential.

3. The semiconductor device for power supply control according to claim 2, characterized in that the output voltage changing circuit comprises: a first current mirror circuit connected to the voltage input terminal and copying a current flowing in the second transistor; and a second current mirror circuit connected to the voltage input terminal and making the current flowing in the first current mirror circuit flow in a return direction, and a current copied by the second current mirror circuit is extracted from a node from which the voltage divided by the first voltage dividing circuit is extracted.

4. The semiconductor device for power supply control according to claim 3, characterized in that ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The output voltage changing circuit includes a second voltage dividing circuit having a fifth resistor element and a sixth resistor element connected in series to the external terminal, and divides a voltage input to the external terminal, The voltage divided by the second voltage dividing circuit is supplied to the second error amplifier.

5. An output voltage variable power supply device, characterized by comprising: A capacitor is externally connected to the output terminal of the semiconductor device for power supply control according to any one of claims 1 to 4.

6. A design method of a semiconductor device for power supply control, which is the design method of the semiconductor device for power supply control according to any one of claims 1 to 4, characterized by comprising: The resistance value of the third resistor element is designed so that the difference between the variation range of the island floating potential applied to the first island region and the variation range of the output voltage which varies in accordance with the voltage of the external terminal becomes small.

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