Semiconductor equipment

Abstract

We provide semiconductor devices that can perform a variety of operations. [Solution] The semiconductor devices 10, 20, 30, and 40 each include a constant current circuit 100, 400 that generates a constant current, and an operation circuit 142, 442 that performs an operation associated with a fixed voltage at one end of a setting resistor and a voltage at the other end of the setting resistor through which a current corresponding to the constant current flows. The voltage at the other end of the setting resistor is a voltage corresponding to the current flowing through the setting resistor. Different fixed voltages at one end of the setting resistor are associated with different operations of the operation circuit.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor device.

Background Art

[0002] Conventionally, it is known to determine the operation in a semiconductor device using an external resistor. For example, Patent Document 1 discloses an LED driving device that generates an output voltage according to the number of switching pulses. In the technique described in Patent Document 1, an internal voltage is divided by two external resistors, a number of switching pulses corresponding to the divided voltage is generated, and an output voltage corresponding to the number of switching pulses is generated. Therefore, the output voltage can be changed by changing the resistance value of the external resistor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] [Summary] However, the present inventors have come to recognize the following problem. In the technique described in Patent Document 1, the voltage generated by the external resistor is a voltage within the range from the ground voltage to the internal voltage, and the number of switching pulses is set for each of a plurality of voltages included in this voltage range. Considering variations such as the voltage generated by voltage division, there is a limit to the number of voltages for which the number of switching pulses can be set within this voltage range. As a result, there is also a limit to the types of output voltages that the LED driving device can generate.

[0005] The present disclosure has been made in view of such a situation, and one of its exemplary purposes is to provide a semiconductor device capable of performing various operations.

[0006] A semiconductor device in one aspect of the present disclosure includes a constant current circuit that generates a constant current, and an operating circuit that performs an operation associated with a fixed voltage at one end of a setting resistor and a voltage at the other end of the setting resistor through which a current corresponding to the constant current flows. The voltage at the other end of the setting resistor is a voltage corresponding to the current flowing through the setting resistor. Different fixed voltages at one end of the setting resistor are associated with different operations of the operating circuit.

[0007] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, etc., are also valid as aspects of this disclosure. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram of the system according to the first embodiment. [Figure 2] Figure 2 illustrates an example of the operation of a semiconductor device when the fixed voltage at one end of the setting resistor is the ground voltage. [Figure 3] Figure 3 is a diagram illustrating an example of the operation of a semiconductor device when the fixed voltage across one end of the setting resistor is the power supply voltage. [Figure 4] Figure 4 shows the relationship between the terminal voltage and the resistance value of the set resistor. [Figure 5] Figure 5 is a table showing the relationship between the setting resistance method and the setting value to the terminal voltage. [Figure 6] Figure 6 is a flowchart showing an example of the operation of a semiconductor device according to the first embodiment. [Figure 7] Figure 7 is a flowchart showing an example of the fixed voltage specification process according to the same embodiment. [Figure 8] Figure 8 is a flowchart showing an example of the terminal voltage identification process according to the same embodiment. [Figure 9] Figure 9 is a flowchart showing an example of the control process of a DC / DC converter according to the same embodiment. [Figure 10] Figure 10 is a block diagram of the system according to the second embodiment. [Figure 11]Figure 11 is a diagram illustrating the operating ranges of the first and second comparators. [Figure 12] Figure 12 is a flowchart showing an example of the operation of a semiconductor device according to the second embodiment. [Figure 13] Figure 13 is a flowchart showing an example of the process for identifying a fixed voltage and determining a comparator according to the same embodiment. [Figure 14] Figure 14 is a block diagram of the system according to the third embodiment. [Figure 15] Figure 15 is a block diagram of the system according to the fourth embodiment. [Figure 16] Figure 16 is a diagram showing the relationship between the resistance value of the setting resistor, the setting resistor method, the constant current, and the terminal voltage according to the same embodiment. [Figure 17] Figure 17 shows a table relating the set values ​​to the current value and terminal voltage of a constant current in a pull-down type. [Figure 18] Figure 18 is a flowchart showing an example of the operation of a semiconductor device according to the fourth embodiment. [Figure 19] Figure 19 is a flowchart showing an example of the constant current determination process according to the same embodiment. [Figure 20] Figure 20 is a flowchart showing an example of the control process of a DC / DC converter according to the same embodiment.

[0009] [Detailed explanation] (overview) This section outlines some exemplary embodiments of the present disclosure. This outline is intended to provide a basic understanding of the embodiments and to simplify some concepts of one or more embodiments, serving as a prelude to the more detailed descriptions that follow. It is not intended to limit the scope of the invention or disclosure. This outline is not a comprehensive overview of all possible embodiments, nor is it intended to identify essential elements of all embodiments or to delineate the scope of some or all aspects. For convenience, “one embodiment” may be used to refer to one or more embodiments (examples or variations) disclosed herein.

[0010] A semiconductor device according to one embodiment includes a constant current circuit that generates a constant current, and an operating circuit that performs operations associated with a fixed voltage at one end of a setting resistor and a voltage at the other end of the setting resistor through which a current corresponding to the constant current flows. The voltage at the other end of the setting resistor is a voltage corresponding to the current flowing through the setting resistor. Different fixed voltages at one end of the setting resistor are associated with different operations of the operating circuit.

[0011] This configuration allows the operation performed by the operating circuit to be switched by switching the fixed voltage at one end of the setting resistor. As a result, the semiconductor device can perform a wider variety of operations through the operating circuit compared to when a single fixed voltage is used.

[0012] In one embodiment, different fixed voltages at one end of a setting resistor may be associated with the voltages at the other ends of multiple setting resistors, each having a different magnitude. Different operations may be associated with the voltages at the other ends of multiple setting resistors associated with the fixed voltages at one end of a setting resistor.

[0013] In one embodiment, the semiconductor device may further include a directional control circuit that controls the direction of the current corresponding to the constant current flowing through a set resistor. The fixed voltage at one end of the set resistor may be a first fixed voltage or a second fixed voltage greater than the first fixed voltage. The directional control circuit may, when the fixed voltage at one end of the set resistor is the first fixed voltage, set the direction of the current flowing through the set resistor to flow from the other end to the one end of the set resistor, and when the fixed voltage at one end of the set resistor is the second fixed voltage, set the direction of the current flowing through the set resistor to flow from one end to the other end of the set resistor.

[0014] In one embodiment, the semiconductor device may further include a reference voltage circuit that generates a reference voltage and is configured to allow switching of the magnitude of the reference voltage, a comparison circuit that includes a comparator for comparing the reference voltage with the voltage at the other end of a set resistor, and a control circuit for controlling the operation of the operating circuit. The control circuit may determine the operation to be performed by the operating circuit based on the comparison result of the comparator.

[0015] In one embodiment, the control circuit may determine a fixed voltage at one end of the setting resistor based on the comparison result of a comparator when no current is flowing through the setting resistor, determine the voltage at the other end of the setting resistor based on the comparison result of a comparator when a current corresponding to a constant current is flowing through the setting resistor, and cause the operating circuit to perform an operation associated with the determined fixed voltage at one end of the setting resistor and the determined voltage at the other end of the setting resistor.

[0016] In one embodiment, the reference voltage circuit may sequentially switch the magnitude of the reference voltage based on the comparison result of the comparator. The control circuit may identify the voltage at the other end of the set resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and cause the operating circuit to perform an operation associated with the identified voltage at the other end of the set resistor.

[0017] In one embodiment, the reference voltage circuit generates a reference voltage by dividing the voltage difference between a first fixed voltage and a second fixed voltage, and the magnitude of the reference voltage may be switched by switching the voltage division ratio.

[0018] In one embodiment, the comparison circuit may include a first comparator configured to operate normally when the input voltage is within a first voltage range, and a second comparator configured to operate normally when the input voltage is within a second voltage range. The lower limit of the first voltage range may be less than or equal to a first fixed voltage. The upper limit of the first voltage range may be less than the second fixed voltage. The lower limit of the second voltage range may be greater than the first fixed voltage. The upper limit of the second voltage range may be greater than or equal to the second fixed voltage. The first and second comparators may each compare a reference voltage with the voltage at the other end of the setting resistor. The control circuit may, if the fixed voltage at one end of the setting resistor is the first fixed voltage, identify the voltage at the other end of the setting resistor based on the comparison result of the first comparator, and if the fixed voltage at one end of the setting resistor is the second fixed voltage, identify the voltage at the other end of the setting resistor based on the comparison result of the second comparator, and cause the operating circuit to perform an operation associated with the identified voltage at the other end of the setting resistor.

[0019] In one embodiment, the semiconductor device may further include a first current mirror circuit that copies a constant current. The direction control circuit may include a second current mirror circuit that copies the current generated by the first current mirror circuit copying the constant current, and a switching circuit configured to switch the current flowing through the setting resistor between the current generated by the first current mirror circuit and the current generated by the second current mirror circuit. The switching circuit may set the direction of the current flowing through the setting resistor to flow from one end to the other of the setting resistor by allowing the current generated by the first current mirror circuit to flow through the setting resistor, and set the direction of the current flowing through the setting resistor to flow from one end to the other of the setting resistor by allowing the current generated by the second current mirror circuit to flow through the setting resistor.

[0020] In one embodiment, the first fixed voltage may be the ground voltage. The second fixed voltage may be the power supply voltage. The first current mirror circuit may consist of two P-channel MOS transistors. The power supply voltage application terminal may be connected to the source of each of the two P-channel MOS transistors.

[0021] In one embodiment, the constant current circuit may include a voltage divider circuit that divides the power supply voltage, an operational amplifier, a MOS transistor, and a resistor placed between the MOS transistor and ground. The MOS transistor may be configured to receive the output signal of the operational amplifier at its gate and allow a constant current to flow. The voltage generated by the voltage divider circuit dividing the power supply voltage may be input to the non-inverting input terminal of the operational amplifier. The voltage at one end of the resistor on the MOS transistor side may be input to the inverting input terminal of the operational amplifier.

[0022] In one embodiment, the semiconductor device may further include an A / D converter that converts the voltage at the other end of a setting resistor into a digital signal, and a control circuit that determines the operation to be performed by the operating circuit based on the digital signal. The control circuit may identify a fixed voltage at one end of the setting resistor based on the digital signal when no current is flowing through the setting resistor, identify the voltage at the other end of the setting resistor based on the digital signal when a current corresponding to a constant current is flowing through the setting resistor, and cause the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor.

[0023] In one embodiment, the constant current circuit may be configured to allow switching of the magnitude of the constant current. The operating circuit performs operations associated with the constant current generated by the constant current circuit, in addition to the fixed voltage at one end of the setting resistor and the voltage at the other end of the setting resistor through which a current corresponding to the constant current flows. Different constant currents of varying magnitudes generated by a constant current circuit may be associated with different operations of the operating circuit.

[0024] In one embodiment, the constant current generated by the constant current circuit may be associated with the voltages at the other ends of a plurality of setting resistors, each having a different magnitude. Different operations may be associated with the voltages at the other ends of the plurality of setting resistors associated with the constant current.

[0025] In one embodiment, the semiconductor device may further include a control circuit for controlling the operation of the operating circuit. The constant current circuit may switch the magnitude of the constant current so that the voltage at one end of the setting resistor is within the range of the voltage that should be generated at the other end of the setting resistor when the voltage at one end of the setting resistor is not within the range of the voltage that should be generated. The control circuit may determine the operation to be performed by the operating circuit based on the constant current generated by the constant current circuit and the voltage at the other end of the setting resistor when the voltage at the other end of the setting resistor is within the range of the voltage that should be generated. The operating circuit may perform the operation determined by the control circuit.

[0026] In one embodiment, the semiconductor device may further include a reference voltage circuit that generates a reference voltage and is configured to allow switching of the magnitude of the reference voltage, and a comparator that compares the reference voltage with the voltage at the other end of a set resistor. The control circuit may determine the operation to be performed by the operating circuit based on the comparison result of the comparator.

[0027] In one embodiment, the reference voltage circuit may generate a reference voltage that is the upper or lower limit of the range of voltages to be generated. The constant current circuit may, based on the comparison result of the comparator when the upper or lower reference voltage is generated, switch the magnitude of the constant current so that the voltage at one end of the setting resistor is within the range of voltages to be generated when the voltage at the other end of the setting resistor is not within the range of voltages to be generated.

[0028] In one embodiment, the constant current circuit may switch the magnitude of the constant current based on the comparison result of the comparator so that the voltage at the other end of the set resistor is within the range of voltages that should be generated. The reference voltage circuit may sequentially switch the magnitude of the reference voltage based on the comparison result of the comparator. The control circuit may identify the voltage at the other end of the set resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and cause the operating circuit to perform an operation associated with the identified voltage at the other end of the set resistor.

[0029] In one embodiment, the constant current circuit may switch the magnitude of the constant current based on the comparison result of a comparator, such that the voltage at the other end of the set resistor is within the range of voltages that should be generated, while the reference voltage is fixed at an upper or lower limit. The reference voltage circuit may sequentially switch the magnitude of the reference voltage after the magnitude of the constant current has been switched so that the voltage at the other end of the set resistor is within the range of voltages that should be generated. The control circuit may identify the voltage at the other end of the set resistor based on the comparison result of a comparator corresponding to the sequential switching of the magnitude of the reference voltage, and cause the operating circuit to perform an operation associated with the identified voltage at the other end of the set resistor.

[0030] In one embodiment, the reference voltage circuit generates a reference voltage by dividing the power supply voltage, and the magnitude of the reference voltage may be switched by switching the voltage division ratio.

[0031] In one embodiment, the semiconductor device may further include an A / D converter that converts the voltage at the other end of a setting resistor into a digital signal. The control circuit may determine the operation to be performed by the operating circuit based on the digital signal.

[0032] In one embodiment, the constant current circuit may switch the magnitude of the constant current based on the digital signal generated by the A / D converter so that the voltage at the other end of the set resistor is within the range of voltages that should be generated. With the magnitude of the constant current fixed so that the voltage at the other end of the set resistor is within the range of voltages that should be generated, the control circuit may identify the voltage at the other end of the set resistor based on the digital signal generated by the A / D converter and cause the operating circuit to perform an operation associated with the identified voltage at the other end of the set resistor.

[0033] In one embodiment, the constant current circuit may generate a first constant current when the resistance value of the set resistor is a first resistance value, and generate a second constant current having a magnitude 1 / N times that of the first constant current when the resistance value of the set resistor is a second resistance value that is N times the first resistance value (where N is a number greater than 1).

[0034] In one embodiment, the semiconductor device may further include a current mirror circuit that copies the constant current generated by the constant current circuit. A current corresponding to the current copied by the current mirror circuit may flow through the setting resistor.

[0035] In one embodiment, the operating circuit may be a DC / DC converter.

[0036] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. Furthermore, the embodiments are illustrative and not limiting to the disclosure and invention, and not all features or combinations thereof described in the embodiments are necessarily essential to the disclosure and invention.

[0037] In this specification, "member A is connected to member B" includes not only cases where member A and member B are directly connected physically, but also cases where member A and member B are indirectly connected via other members that do not substantially affect their electrical connection or impair the functions or effects produced by their combination.

[0038] Similarly, "member C is connected (provided) between member A and member B" includes not only cases where member A and member C, or member B and member C, are directly connected, but also cases where they are indirectly connected via other members that do not substantially affect their electrical connection state or impair the function or effect produced by their combination.

[0039] In this specification, the symbols attached to electrical signals such as voltage signals and current signals, or to circuit elements such as resistors, capacitors, and inductors, shall represent the respective voltage values, current values, or circuit constants (resistance values, capacitance values, and inductance) as needed.

[0040] In this specification, "integrated integration" includes cases where all components of a circuit are formed on a semiconductor substrate, or cases where the main components of a circuit are integrally integrated, and some resistors, capacitors, etc. may be provided outside the semiconductor substrate for adjusting circuit constants.

[0041] (First Embodiment) FIG. 1 is a block diagram of a system 1 according to the first embodiment. The system 1 according to this embodiment includes a semiconductor device 10 and an external setting resistor R SET , SET , SET . The semiconductor device 10 according to this embodiment may be configured as a PMIC (Power Management Integrated Circuit). Specifically, the semiconductor device 10 may have a plurality of power supply circuits (not shown).

[0042] The semiconductor device 10 has a constant current circuit 100, a first current mirror circuit 104, a direction control circuit 110, a reference voltage circuit 120, a comparator 130, a control circuit 140, a DC / DC converter 142, an oscillator 144, a setting terminal SR, and an output terminal OUT. The semiconductor device 10 executes an operation according to a setting value corresponding to the resistance value of the setting resistor R SET and outputs an output voltage V OUT1 from the output terminal OUT.

[0043] The fixed voltage at one end of the setting resistor R SET according to this embodiment is the first fixed voltage or a second fixed voltage greater than the first fixed voltage. Specifically, the fixed voltage at one end of the setting resistor R SET is the ground voltage (V SS ) which is the first fixed voltage or the power supply voltage V DD which is the second fixed voltage. The fixed voltage is a voltage that does not change due to the current flowing through the setting resistor R SET . The other end of the setting resistor R SET is connected to the setting terminal SR.

[0044] The setting resistor R SET is replaceable, and by replacing the setting resistor R SET , the setting resistor R SETThe resistance value can be changed. Setting resistance R SET The fixed voltage at one end is the power supply voltage V DD It can be switched between the voltage and the ground voltage. Therefore, the setting resistor R SET This can be switched using pull-up and pull-down resistors.

[0045] The constant current circuit 100 provides a constant current I CON1 The constant current circuit 100 includes a voltage divider circuit 101, an operational amplifier 102, a transistor MN1, and a resistor R3.

[0046] The voltage divider circuit 101 controls the power supply voltage V DD The voltage is divided. The voltage divider circuit 101 divides the power supply voltage V DD Voltage V is generated by dividing the voltage. 1+ This is input to the non-inverting input terminal of the operational amplifier 102. The voltage divider circuit 101 according to this embodiment includes two resistors R1 and R2 connected in series.

[0047] One end of resistor R1 is connected to the power supply voltage V DD The application terminal of resistor R1 is connected, and the other end of resistor R1 is connected to the non-inverting input terminal of op-amp 102. One end of resistor R2 is connected to the non-inverting input terminal of op-amp 102, and the other end of resistor R2 is connected to the application terminal of the ground voltage (also called "ground"). Power supply voltage V DD Voltage V generated by voltage division 1+ This can be expressed by the following equation (1). V 1+ =V DD ×R2 / (R1+R2)···(1)

[0048] Transistor MN1 is composed of a MOS (Metal Oxide Semiconductor) transistor. Transistor MN1 in this embodiment is an N-channel type MOS transistor. Transistor MN1 in this embodiment receives the output signal S of the operational amplifier 102. AMP1 The gate receives a constant current I CON1 It is designed to allow for flow.

[0049] Resistor R3 is placed between transistor MN1 and ground. Specifically, one end of resistor R3 is connected to the source of transistor MN1, and the other end of resistor R3 is connected to ground. A constant current I is supplied through resistor R3. CON1 When the current flows, a voltage V is present at one end of resistor R3 on the transistor MN1 side. 1- This occurs. Voltage V 1- This can be expressed by the following equation (2). V 1- =R3×I CON1 ...(2) Voltage V 1- This is input to the inverting input terminal of the operational amplifier 102.

[0050] The operational amplifier 102 receives the voltage V input to its non-inverting input terminal. 1+ and the voltage V input to the inverting input terminal 1- (V 1+ =V 1- ) Thus, the output voltage S AMP1 This generates a constant current I CON1 From equations (1) and (2), it can be expressed by the following equation (3). I CON1 =V DD ×R2 / {R3×(R1+R2)}···(3)

[0051] The first current mirror circuit 104 receives the constant current I generated by the constant current circuit 100. CON1 Copy this. The first current mirror circuit 104 according to this embodiment includes two transistors MP1 and MP2. The two transistors MP1 and MP2 are each composed of P-channel type MOS transistors. Transistor MP1 is the input side transistor, and transistor MP2 is the output side transistor.

[0052] The power supply voltage V is supplied to the source of each transistor MP1 and MP2. DD The application terminals are connected. The gate of transistor MP1 is connected to the drain of transistor MP1, in common with the gate of transistor MP2. The drain of transistor MP1 is connected to the drain of transistor MN1.

[0053] The direction control circuit 110 has a setting resistor R SET Constant current I flowing through CON1 The direction of the current is controlled accordingly. Specifically, the direction control circuit 110 controls the setting resistor R. SET If the fixed voltage at one end is the ground voltage, then the setting resistor R SET The direction of the current flowing through it is set by resistor R. SET The direction is from the other end to the one end. The direction control circuit 110 has a setting resistor R SET A fixed voltage at one end is the power supply voltage V DD If so, the setting resistor R SET The direction of the current flowing through it is set by resistor R. SET This refers to the direction from one end to the other.

[0054] The direction control circuit 110 according to this embodiment includes a second current mirror circuit 112 and a switching circuit 114.

[0055] The second current mirror circuit 112 is controlled by the first current mirror circuit 104, which is constantly current I CON1 The current generated by copying is copied. The second current mirror circuit 112 according to this embodiment includes two transistors MN2 and MN3. The two transistors MN2 and MN3 are each composed of N-channel type MOS transistors. Transistor MN2 is the input transistor, and transistor MN3 is the output transistor. The sources of transistors MN2 and MN3 are connected to ground. The gate of transistor MN2 is connected to the drain of transistor MN2, in common with the gate of transistor MN3.

[0056] The switching circuit 114 has a setting resistor R SET The circuit is configured to allow switching between a current generated by copying the current flowing through the first current mirror circuit 104 and a current generated by copying the current flowing through the second current mirror circuit 112. The switching circuit 114 sets the current generated by copying the current flowing through the first current mirror circuit 104 using a setting resistor R SET By flowing through it, the setting resistor R SETThe direction of the current flowing through it is set by resistor R. SET The direction can be from the other end to the one end. Furthermore, the switching circuit 114 sets the current generated by the second current mirror circuit 112 using a setting resistor R. SET By flowing through it, the setting resistor R SET The direction of the current flowing through it is set by resistor R. SET This can be defined as the direction from one end to the other.

[0057] The switching circuit 114 according to this embodiment includes a first switch SW1, a second switch SW2, and a common line 115. The first switch SW1 can switch the connection destination of the drain of transistor MP2 between the common line 115 and the drain of transistor MN2. The first switch SW1 can also open the drain of transistor MP2. The second switch SW2 can switch the connection destination of the setting terminal SR between the common line 115 and the drain of transistor MN3. The second switch SW2 can also open the setting terminal SR.

[0058] The reference voltage circuit 120 has a reference voltage V REF1 Generates a reference voltage V REF1 The size of the reference voltage is configured to be switchable. The reference voltage circuit 120 divides the voltage difference between the first fixed voltage and the second fixed voltage to create a reference voltage V REF1 This generates the power supply voltage V. In this embodiment, the reference voltage circuit 120 generates the power supply voltage V. DD Dividing the voltage to obtain a reference voltage V REF1 Generates a reference voltage V. REF1 This is input to the inverting input terminal of comparator 130.

[0059] The reference voltage circuit 120 includes two resistors R4 and R5 connected in series, a third switch SW3, and a fourth switch SW4. The two resistors R4 and R5 are each variable resistors. The third switch SW3 connects the power supply voltage V to one of the ends of resistor R4 opposite to resistor R5 and the end of resistor R5 opposite to resistor R4. DDThe fourth switch SW4 is provided so that the applied terminals can be connected. The fourth switch SW4 is provided so that one of the ends of resistor R4 opposite to resistor R5 and the end of resistor R5 opposite to resistor R4 can be connected to ground.

[0060] The reference voltage circuit 120 allows the voltage division ratio to be switched, thereby changing the reference voltage V REF1 The magnitude is switched. Specifically, by switching the resistance values ​​of resistors R4 and R5, the reference voltage V REF1 The size can be switched.

[0061] The comparator 130 may be configured as, for example, a rail-to-rail comparator. The comparator 130 constitutes a comparison circuit. The comparator 130 uses a reference voltage V REF1 and terminal voltage V SR1 The comparison signal S shows the comparison result when compared with the other signal. CMP1 Generates comparison signal S. CMP1 The terminal voltage V SR1 The reference voltage V REF1 If it is greater than V, it becomes a high signal, and the terminal voltage V SR1 The reference voltage V REF1 If it is smaller than this, the signal is low. Comparison signal S CMP1 This is input to the control circuit 140.

[0062] The control circuit 140 may be configured by combining various logic circuits. The control circuit 140 comprehensively controls the operation of the semiconductor device 10. For example, the control circuit 140 controls the operation of the DC / DC converter 142. Specifically, the control circuit 140 controls the setting resistor R SET A fixed voltage at one end and a constant current I CON1 A setting resistor R through which a current corresponding to the current flows. SET The voltage at the other end (terminal voltage V) SR1 The DC / DC converter 142 is made to perform the operation associated with ). Setting resistor R SET Different fixed voltages at one end are associated with different operations of the DC / DC converter 142.

[0063] The control circuit 140 according to this embodiment determines the operation to be executed by the DC / DC converter 142 based on the comparison result of the comparator 130. Specifically, the control circuit 140 determines the operation based on the comparison signal S CMP1 and determines the operation associated with the fixed voltage at one end of the setting resistor R SET and the terminal voltage V SR1 , and generates a control signal S DC1 for causing the determined operation to be executed by the DC / DC converter 142.

[0064] The control circuit 140 according to this embodiment can generate a signal S SW for switching the switch. The signal S SW includes a signal S SW1 for switching the first switch SW1 and the second switch SW2, and a signal S SW2 for switching the third switch SW3 and the fourth switch SW4. The control circuit 140 may generate a signal S R1 for switching the resistance values of the resistors R4 and R5 in the reference voltage circuit 120.

[0065] The DC / DC converter 142 generates an output voltage V IN corresponding to the input voltage V OUT1 . The DC / DC converter 142 executes an operation associated with the fixed voltage at one end of the setting resistor R SET and the voltage at the other end of the setting resistor R CON1 through which a current corresponding to the constant current I SET flows (terminal voltage V SR1 ). In this embodiment, the DC / DC converter 142 executes the operation determined by the control circuit 140.

[0066] The oscillator 144 generates a clock signal S CLK . The clock signal S CLK is transmitted to the control circuit 140 and the DC / DC converter 142, and the control circuit 140 and the DC / DC converter 142 operate according to the clock signal S CLK , respectively.

[0067] FIG. 2 shows the setting resistor RSET This figure illustrates an example of operation of the semiconductor device 10 when the fixed voltage at one end is the ground voltage. As shown in Figure 2, the setting resistor R SET One end is connected to ground. Therefore, the setting resistor R SET This is a pull-down resistor.

[0068] The switching circuit 114 has a setting resistor R SET When it is a pull-down resistor, it may be set to a pull-down configuration. Specifically, the first switch SW1 connects the drain of transistor MP2 to the common line 115, and the second switch SW2 connects the setting terminal SR to the common line 115.

[0069] The first current mirror circuit 104 generates a constant current I CON1 The current I generated by copying MR1 The setting resistor R is connected via common line 115. SET It flows through. At this time, the current I, represented by the following equation (4), flows through the setting terminal SR. MR1 The corresponding voltage V SR1 This will occur. V SR1 =R SET ×I MR1 ...(4)

[0070] The reference voltage circuit 120 has a setting resistor R. SET When it is a pull-down resistor, it may be set to a pull-down configuration. Specifically, the third switch SW3 is connected to the power supply voltage V on one end of resistor R5 opposite to resistor R4. DD The applied terminal of the resistor R4 is connected, and the fourth switch SW4 connects the opposite end of resistor R4 to ground. Reference voltage V REF1 is the power supply voltage V DD It is expressed by the following equation (5) when the voltages are divided. V REF1 =V DD ×R4 / (R4+R5)···(5)

[0071] Figure 3 shows the setting resistor R. SET A fixed voltage at one end is the power supply voltage V DDThis figure illustrates an example of the operation of the semiconductor device 10 when the following conditions are met. As shown in Figure 3, the setting resistor R SET One end of the power supply voltage V DD The application terminal is connected. Therefore, the setting resistor R SET This is a pull-up resistor.

[0072] The switching circuit 114 has a setting resistor R SET When it is a pull-up resistor, it may be set to a pull-up configuration. Specifically, the first switch SW1 connects the drain of transistor MP2 to the drain of transistor MN2, and the second switch SW2 connects the setting terminal SR to the drain of transistor MN3.

[0073] The first current mirror circuit 104 generates a constant current I CON1 The current I generated by copying MR1 This is copied by the second current mirror circuit 112. The second current mirror circuit 112 is current I MR1 The current I generated by copying MR2 This is the setting resistor R SET It flows through. At this time, the current I, represented by the following equation (6), flows through the setting terminal SR. MR2 The corresponding voltage V SR1 This will occur. V SR1 =V DD -R SET ×I MR2 ...(6)

[0074] The reference voltage circuit 120 has a setting resistor R. SET When it is a pull-up resistor, it may be set to a pull-up configuration. Specifically, the third switch SW3 is connected to the power supply voltage V on one end of resistor R4 opposite to resistor R5. DD The applied terminal of the resistor is connected, and the fourth switch SW4 connects the opposite end of resistor R5 to ground. Reference voltage V REF1 is the power supply voltage V DD It is expressed by the following equation (7) when divided by voltage. V REF1 =V DD ×R5 / (R4+R5)···(7)

[0075] According to the semiconductor device 10 of this embodiment, the power supply voltage of the constant current circuit 100, the power supply voltage of the first current mirror circuit 104, and the setting resistor R SET The power supply voltage at one end and the power supply voltage divided by the reference voltage circuit 120 are V DD They are common in this respect. Therefore, the power supply voltage V DD If a fluctuation occurs, constant current I CON1 and reference voltage V REF1 Since the power supply voltage V also fluctuates in proportion to that fluctuation, the semiconductor device 10 will be affected by the power supply voltage V DD This circuit is robust against fluctuations.

[0076] Specifically, the power supply voltage V DD If the terminal voltage V changes by a factor of n, SR1’ and reference voltage V REF1’ It can be expressed by the following formula. V SR1’ =(V DD ×n)-(R SET ×I MR2 ×n) = n × V SR1 V REF1’ =V DD ×n × R5 / (R4 + R5) = n × V REF1 Thus, terminal voltage V SR1 and reference voltage V REF1 Power supply voltage V DD To track the fluctuations, the power supply voltage V is applied to the comparison result in comparator 130. DD The impact of these fluctuations is suppressed.

[0077] Figure 4 shows the setting resistor R. SET Terminal voltage V with respect to resistance SR1 This figure shows the relationship. Figure 4 shows the terminal voltage V expressed by equation (4). SR1 The dashed line indicates the terminal voltage V, which is represented by equation (6). SR1 This is shown by a solid line. In this embodiment, the setting resistor R SET R 11 ~R 14 Let R be able to take on four resistance values. 11 <R 12 <R 13<R 14 That is the case. Note that the setting resistor R SET The number of possible resistance values ​​may be three or fewer, or five or more.

[0078] In the case of a pull-down type, the setting resistor R SET Resistance value R 11 ~R 14 When taking the terminal voltage V SR1 V D11 ~V D14 This is the result. Here, V D11 <V D12 <V D13 <V D14 That is the case. On the other hand, in the case of a pull-up type, the setting resistor R SET Resistance value R 11 ~R 14 When taking the terminal voltage V SR1 V U11 ~V U14 This is the result. Here, V U11 >V U12 >V U13 >V U14 That is the case.

[0079] Figure 5 shows the setting resistor R. SET The method and setting terminal SR voltage V D11 ~V D14 ,V U11 ~V U14 This figure shows Table 141, which associates the set values. Below, the components of the semiconductor device 10 will be described in more detail with reference to Figure 5.

[0080] As shown in Figure 5, the setting resistor R SET1 Each of the fixed voltages at one end is controlled by multiple setting resistors R, each having a different magnitude. SET1 The voltage at the other end (terminal voltage V) SR1 ) is associated with it. More specifically, in the pull-down type, the voltage V D11 ~V D14 In the pull-up type, the voltage V U11 ~V U14 They are associated.

[0081] Setting resistance RSET Multiple terminal voltages V associated with a fixed voltage at one end SR1 Each of these is associated with a different operation. In this embodiment, voltage V D11 ~V D14 ,V U11 ~V U14 Each of these is associated with a different setting value, and a different operation is assigned to each setting value. This allows the voltage V D11 ~V D14 ,V U11 ~V U14 Different actions are associated with this.

[0082] Specifically, the voltage V associated with the pull-down type. D11 ~V D14 A setting value of 1 to 4 is associated with this. Also, the voltage V associated with the pull-up is... U11 ~V U14 Each of these settings is associated with a setting value of 5 to 8. These setting values ​​1 to 8 are assigned to different operations of the DC / DC converter 142. This allows the DC / DC converter 142 to perform eight different operations.

[0083] The set value includes, for example, the output voltage V of the DC / DC converter 142. OUT1 Different operations may be assigned to the voltage value and the control method of the DC / DC converter 142. The control method of the DC / DC converter 142 may be, for example, PFM (Pulse Frequency Modulation) control and FPWM (Forced Pulse Width Modulation) control.

[0084] The reference voltage circuit 120 according to this embodiment has a terminal voltage V SR1 It can generate a voltage to identify [the target].

[0085] For example, in the pull-down type, the reference voltage circuit 120 has a first reference voltage V DREF1 , second reference voltage V DREF2 , third reference voltage V DREF3 and the fourth reference voltage V DREF4It can generate the first reference voltage V DREF1 V D11 <V DREF1 <V D12 The conditions are met, and the second reference voltage V DREF2 V D12 <V DREF2 <V D13 The conditions are met, and the third reference voltage V DREF3 V D13 <V DREF3 <V D14 The fourth reference voltage V satisfies the following conditions. DREF4 V D14 <V DREF4 <V DD It satisfies the condition.

[0086] Furthermore, in the pull-up type, the reference voltage circuit 120 is the first reference voltage V UREF1 , second reference voltage V UREF2 , third reference voltage V UREF3 and the fourth reference voltage V UREF4 It can generate the first reference voltage V UREF1 V U14 <V UREF1 <V U13 The conditions are met, and the second reference voltage V UREF2 V U13 <V UREF2 <V U12 The conditions are met, and the third reference voltage V UREF3 V U12 <V UREF3 <V U11 The fourth reference voltage V satisfies the following conditions. UREF4 V U11 <V UREF4 <V DD It satisfies the condition.

[0087] In this embodiment, the reference voltage circuit 120 calculates the reference voltage V based on the comparison result of the comparator 130. REF1 The magnitude of can be switched sequentially. For example, the reference voltage circuit 120 sets the reference voltage V based on the comparison result of the comparator 130. REF1 The size of V DREF1 ,V UREF1 It may be increased sequentially from there. Alternatively, the reference voltage circuit 120 may set the reference voltage V based on the comparison result of the comparator 130. REF1The size of V DREF4 ,V UREF4 You can gradually lower it from there.

[0088] In this embodiment, the control circuit 140 can determine the operation to be performed by the DC / DC converter 142 by referring to the table 141, and cause the DC / DC converter 142 to perform the determined operation. Specifically, the control circuit 140 controls the setting resistor R SET Identify the fixed voltage at one end and set a constant current I CON1 Current I corresponding to the current I MR1 ,I MR2 The setting resistor R SET Terminal voltage V when current flows through it SR1 The control circuit 140 determines the operation performed by the DC / DC converter 142 based on the identified setting resistor R. SET Fixed voltage at one end and specified terminal voltage V SR1 The behavior assigned to the associated setting value is determined.

[0089] The control circuit 140 according to this embodiment has a setting resistor R SET Based on the comparison result of comparator 130 when no current is flowing, the setting resistor R SET The fixed voltage at one end is identified. Furthermore, the control circuit 140 controls the constant current I CON1 Current I corresponding to the current I MR1 ,I MR2 The setting resistor R SET Based on the comparison result of comparator 130 when current is flowing, the setting resistor R SET The voltage at the other end (terminal voltage V) SR1 ) is identified. Furthermore, the control circuit 140 identifies the identified set resistor R SET A fixed voltage at one end and a specified setting resistor R SET The DC / DC converter 142 is made to perform an operation associated with the voltage at the other end of the device.

[0090] The control circuit 140 according to this embodiment uses a reference voltage V REF1 Based on the comparison results of the comparator 130 in response to the sequential switching of the magnitude, the terminal voltage V SR1 Identify the identified terminal voltage V SR1The DC / DC converter 142 can be made to perform the associated operation. For example, when the control circuit 140 is pull-down, the terminal voltage V SR1 The second reference voltage V DREF2 Larger than the third reference voltage V DREF3 If the comparison result of comparator 130 shows that it is smaller than, then the terminal voltage V SR1 Voltage V D13 It may be determined that this is the case. In this case, the control circuit 140 controls the voltage V D13 The DC / DC converter 142 is instructed to perform the action associated with this, i.e., the action assigned to setting value 3.

[0091] Figure 6 is a flowchart showing an example of operation of the semiconductor device 10 according to this embodiment. The following describes an example of operation of the semiconductor device 10 in accordance with the flowchart shown in Figure 6.

[0092] First, the semiconductor device 10 performs a fixed voltage determination process (S10). The fixed voltage determination process involves setting the resistor R SET This is a process to identify a fixed voltage at one end. Next, the semiconductor device 10 performs a terminal voltage identification process (S12). The terminal voltage identification process involves a constant current I CON1 The current corresponding to the set resistor R SET Terminal voltage V when current flows through it SR1 This is the process of identifying [something].

[0093] Next, the semiconductor device 10 performs control processing for the DC / DC converter (S14). The control processing for the DC / DC converter is performed using the fixed voltage specified in S10 and the terminal voltage V specified in S12. SR1 This process causes the DC / DC converter 142 to execute the associated operation. Once the DC / DC converter control process is executed, the process shown in Figure 6 is completed.

[0094] Figure 7 is a flowchart showing an example of the fixed voltage identification process (S10) according to this embodiment. The flow of the fixed voltage identification process will be explained below in accordance with the flowchart shown in Figure 7.

[0095] First, the control circuit 140 opens the setting terminal SR (S101). Specifically, the control circuit 140 switches the second switch SW2 so that the setting terminal SR is not connected to either the common line 115 or the drain of transistor MN3. This allows the setting resistor R to be opened. SET No current flows through it, and the terminal voltage V SR1 This is the setting resistor R SET This becomes a fixed voltage at one end.

[0096] Next, the control circuit 140 sets the reference voltage circuit 120 to a pull-down type (S103). This sets the power supply voltage V DD The reference voltage V obtained by dividing the voltage REF1 This is generated.

[0097] Next, the comparator 130 measures the terminal voltage V SR1 The reference voltage V REF1 Determine whether it is greater than or equal to (S105). Terminal voltage V SR1 The reference voltage V REF1 If it is determined to be greater than (S105: YES), proceed to step S107. Meanwhile, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be smaller than (S105: NO), proceed to S113.

[0098] In S105, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be greater than the set resistor R, the control circuit 140 will set the resistor R SET A fixed voltage at one end is the power supply voltage V DD It is identified as such (S107). Next, the control circuit 140 sets the switching circuit 114 to a pull-up configuration (S109). Next, the control circuit 140 sets the reference voltage circuit 120 to a pull-up configuration (S111). Once the reference voltage circuit 120 is set to a pull-up configuration, the process of identifying the fixed voltage is completed.

[0099] In S105, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be smaller than the set resistor R, the control circuit 140 will set the resistor RSET The fixed voltage at one end is identified as the ground voltage (S113). Next, the control circuit 140 sets the switching circuit 114 to a pull-down type (S115). Once the switching circuit 114 is set to a pull-down type, the fixed voltage determination process is completed.

[0100] Figure 8 is a flowchart showing an example of the terminal voltage identification process (S12) according to this embodiment. The flow of the terminal voltage identification process will be explained below in accordance with the flowchart shown in Figure 8.

[0101] First, the reference voltage circuit 120 has a minimum reference voltage V REF1 Generates (S121). Minimum reference voltage V REF1 In the case of a pull-down type, the first reference voltage V DREF1 In the case of a pull-up type, the first reference voltage V UREF1 That is the case.

[0102] Next, the comparator 130 measures the terminal voltage V SR1 The reference voltage V REF1 Determine whether it is smaller than (S123). Terminal voltage V SR1 The reference voltage V REF1 If it is determined to be smaller than (S123: YES), proceed to S129. Meanwhile, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be greater than (S123: NO), proceed to S125.

[0103] In S123, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be greater than the reference voltage V, the control circuit 140 will REF1 It is determined whether the value is at its maximum (S125). The control circuit 140 controls the reference voltage V REF1 The third reference voltage V DREF3 ,V UREF3 When the reference voltage V is present, REF1 It is determined that this is the maximum, and the reference voltage V REF1 The third reference voltage V DREF3 ,V UREF3 When the reference voltage V is smaller than REF1It can be determined that it is not the maximum. Reference voltage V REF1 If it is determined that is the maximum (S125: YES), proceed to S129. Meanwhile, the reference voltage V REF1 If it is determined that the value is not the maximum (S125: NO), proceed to S127.

[0104] In S125, the reference voltage V REF1 If it is determined that the reference voltage V is not at its maximum, the control circuit 140 will REF1 Increase the value (S127). The control circuit 140 controls the reference voltage V REF1 The first reference voltage V DREF1 ,V UREF1 When this is the case, the reference voltage V REF1 The second reference voltage V DREF2 ,V UREF2 Raise the reference voltage V REF1 The second reference voltage V DREF2 ,V UREF2 When this is the case, the reference voltage V REF1 The third reference voltage V DREF3 ,V UREF3 It is OK to raise it to the reference voltage V. REF1 When it goes up, it returns to S123.

[0105] In S123, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be smaller than or the reference voltage V in S125 REF1 When it is determined that the terminal voltage V is at its maximum, the control circuit 140 controls the terminal voltage V SR1 Identify (S129).

[0106] In S123, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be lower than the specified value, the control circuit 140 will, in the case of a pull-down type, control the voltage V D11 ~V D14 Of these, the reference voltage V in S123 REF1 Lower than the reference voltage V REF1 The voltage closest to the terminal voltage V SR1 It may be specified that it is. For example, the reference voltage V in S123 REF1 The third reference voltage V DREF3If so, the control circuit 140 will control the terminal voltage V SR1 Voltage V D13 It can be identified as such. Also, in the case of the pull-up type, the control circuit 140 has a voltage V U11 ~V U14 Of these, the reference voltage V in S123 REF1 Lower than the reference voltage V REF1 The voltage closest to the terminal voltage V SR1 It can be identified as such.

[0107] In S125, the reference voltage V REF1 If it is determined that the value is the maximum, the control circuit 140 will, in the case of a pull-down type, the terminal voltage V SR1 Voltage V D14 It may be determined that this is the case. In the case of the pull-up type, the control circuit 140 has a terminal voltage V SR1 Voltage V U14 It can be identified as such.

[0108] In S129, terminal voltage V SR1 Once the terminal voltage is identified, the process of identifying the terminal voltage ends.

[0109] Figure 9 is a flowchart showing an example of the control process (S14) of the DC / DC converter according to this embodiment. The flow of the DC / DC converter control process will be explained below in accordance with the flowchart shown in Figure 9.

[0110] First, the control circuit 140 determines the operation to be performed by the DC / DC converter 142 (S141). The control circuit 140 determines the operation to be performed by the DC / DC converter 142 by setting the resistor R identified in S10. SET The fixed voltage at one end and the terminal voltage V specified in S12 SR1 Determine the associated operation. For example, the setting resistor R SET A fixed voltage at one end is the power supply voltage V DD It is specified as the terminal voltage V SR1 Voltage V U13 If this is determined, the control circuit 140 may decide to have the DC / DC converter 142 perform the operation assigned to the setting value 7.

[0111] Next, the control circuit 140 causes the DC / DC converter 1 to execute the operation determined in S141 (S143). Once the DC / DC converter 142 executes the determined operation, the control process for the DC / DC converter ends.

[0112] The configuration and operation of the system 1 and its semiconductor device 10 according to this embodiment have been described above. The semiconductor device 10 according to this embodiment has a constant current I CON1 A constant current circuit 100 that generates a set resistor R SET A fixed voltage at one end and a constant current I CON A setting resistor R through which a current corresponding to the current flows. SET The voltage at the other end (terminal voltage V) SR1 It includes an operating circuit (DC / DC converter 142) that performs an operation associated with the terminal voltage V. SR1 This is the setting resistor R SET This is the voltage corresponding to the current flowing through it. Setting resistor R SET Different fixed voltages at one end are associated with different operations of the DC / DC converter 142.

[0113] According to this configuration, the setting resistor R SET By switching the fixed voltage at one end, it becomes possible to switch the operation performed by the DC / DC converter 142. As a result, the semiconductor device 10 can perform a wider variety of operations using the DC / DC converter 142 compared to when a single fixed voltage is used.

[0114] Terminal voltage V SR1 , reference voltage V REF1 Furthermore, variations occur in the offset of comparator 130, etc., so the two adjacent reference voltages V REF1A certain interval is required between them. Therefore, when using either a pull-down resistor or a pull-up resistor, the number of set values ​​is limited, and the number of operations that the DC / DC converter 142 can perform is also limited. In contrast, according to the semiconductor device 10 of this embodiment, different set values ​​are assigned to the pull-down resistor and the pull-up resistor, making it possible to have the DC / DC converter 142 perform a variety of operations.

[0115] (Second Embodiment) Figure 10 is a block diagram of system 2 according to the second embodiment. The semiconductor device 20 in system 2 according to the second embodiment differs from the semiconductor device 10 according to the first embodiment mainly in the configuration of the comparison circuit.

[0116] The semiconductor device 20 according to the second embodiment includes a constant current circuit 100, a first current mirror circuit 104, a direction control circuit 110, a reference voltage circuit 120, a comparator circuit 230, a control circuit 240, a DC / DC converter 142, an oscillator 144, a setting terminal SR, and an output terminal OUT.

[0117] The comparator circuit 230 according to the second embodiment includes a first comparator 232, a second comparator 234, and a multiplexer 236. In this embodiment, the first comparator 232 and the second comparator 234 are not rail-to-rail comparators, but rather compare the ground voltage to the power supply voltage V DD This comparator can operate normally within a specified input voltage range, which is narrower than the range up to [specific point].

[0118] The first comparator 232 and the second comparator 234 operate normally over different input voltage ranges. In this embodiment, the first comparator 232 operates under the first voltage range V RNG1 Configured to operate normally when the input voltage is within the second voltage range V, the second comparator 234 checks when the input voltage is within the second voltage range V RNG2 It is configured to function correctly when it is inside.

[0119] First voltage range V RNG1 Lower limit voltage VMIN1 is less than or equal to the first fixed voltage, and the first voltage range V RNG1 The upper limit voltage V MAX1 This is smaller than the second fixed voltage. In this embodiment, the first voltage range V RNG1 Lower limit voltage V MIN1 This is the ground voltage, and the first voltage range V RNG1 The upper limit voltage V MAX1 is the power supply voltage V DD Smaller than. Second voltage range V RNG2 Lower limit voltage V MIN2 This is greater than the first fixed voltage, and the second voltage range V RNG2 The upper limit voltage V MAX2 This is greater than or equal to the second fixed voltage. In this embodiment, the second voltage range V RNG2 Lower limit voltage V MIN2 It is greater than the ground voltage, and is in the second voltage range V RNG2 The upper limit voltage V MAX2 is the power supply voltage V DD That is the case.

[0120] The first comparator 232 uses a reference voltage V REF1 and terminal voltage V SR1 Compare with the comparison signal S CMP21 Generates comparison signal S. CMP21 The reference voltage V REF1 The terminal voltage is V SR1 If it is greater than V, it becomes a high signal, and the reference voltage V REF1 The terminal voltage is V SR1 If it is smaller than V, the signal is low. The second comparator 234 uses a reference voltage V REF1 and terminal voltage V SR1 Compare with the comparison signal S CMP22 Generates comparison signal S. CMP22 The terminal voltage V SR1 The reference voltage V REF1 If it is greater than V, it becomes a high signal, and the terminal voltage V SR1 The reference voltage V REF1 If it is smaller than this, it becomes a low signal.

[0121] The multiplexer 236 receives the comparison signal S generated by the first comparator 232. CMP21and the comparison signal S generated by the second comparator 234 CMP2 Select one of the two and select the comparison signal S CMP23 The multiplexer 236 outputs the signal S generated by the control circuit 240. SEL The comparison signal to be selected can be determined accordingly.

[0122] The control circuit 240 controls the operation of the DC / DC converter 142. In this embodiment, the control circuit 240 controls the comparison signal S output by the multiplexer 236. CMP23 Based on this, the operation to be performed by the DC / DC converter 142 is determined, and a signal S is given to the DC / DC converter 142 to perform that operation. DC1 Generates.

[0123] The control circuit 240 according to this embodiment has a setting resistor R SET If the fixed voltage at one end is the ground voltage, then the terminal voltage V is determined based on the comparison result of the first comparator 232. SR1 Identify the setting resistor R. SET A fixed voltage at one end is the power supply voltage V DD In that case, the terminal voltage V is determined based on the comparison result of the second comparator 234. SR1 The control circuit 240 identifies the identified terminal voltage V. SR1 The DC / DC converter 142 is instructed to perform the associated operation.

[0124] Figure 11 is a diagram illustrating the operating ranges of the first comparator 232 and the second comparator 234. The first voltage range V is the operating range of the first comparator 232. RNG1 When it is a pull-down type, the terminal voltage V SR1 V that can be taken D11 ~V D14 and includes ground voltage (0V). First voltage range V RNG1 Lower limit voltage V MIN1 It is 0V, and the first voltage range V RNG1 The upper limit voltage V MAX1 V D14 <V MAX1 <V DDThe second voltage range V is the operating range of the second comparator 234. RNG2 When using a pull-up resistor, the terminal voltage V SR1 V that can be taken U11 ~V U14 and power supply voltage V DD Includes. Second voltage range V RNG2 Lower limit voltage V MIN2 is, 0 <V MIN1 <V U11 Satisfying the second voltage range V RNG2 The upper limit voltage V MAX2 V DD That is the case.

[0125] First voltage range V RNG1 This is a pull-up voltage V U11 and power supply voltage V DD It does not include the second voltage range V RNG2 This is a pull-down V D11 and does not include the ground voltage. Thus, one comparator can measure the power supply voltage V from the ground voltage. DD Even if it is not possible to cover all voltages up to the ground voltage, by using two comparators, the first comparator 232 and the second comparator 234, the power supply voltage V can be measured from the ground voltage. DD It will be possible to cover all voltages up to that point.

[0126] Figure 12 is a flowchart showing an example of operation of the semiconductor device 20 according to the second embodiment. The example of operation of the semiconductor device 20 will be described below in accordance with the flowchart shown in Figure 12.

[0127] First, the semiconductor device 20 performs a process to determine a fixed voltage and a process to determine a comparator (S20). This process involves setting the resistor R SET Identify the fixed voltage at one end, and the terminal voltage V SR1 This is the process of determining the comparator to be used to identify [the specific element].

[0128] Next, the semiconductor device 20 performs terminal voltage identification processing (S24) and DC / DC converter control processing (S26). However, since these processes are substantially the same as the terminal voltage identification processing (S12) and DC / DC converter control processing (S14) according to the first embodiment, their explanation is omitted here. Once the DC / DC converter control processing is executed, the process shown in Figure 12 is completed.

[0129] Figure 13 is a flowchart showing an example of the fixed voltage identification process and comparator determination process (S20) according to this embodiment. The flow of the fixed voltage identification process and comparator determination process will be explained below in accordance with the flowchart shown in Figure 13.

[0130] First, the control circuit 240 opens the setting terminal SR (S201). Specifically, the control circuit 240 switches the second switch SW2 so that the setting terminal SR is not connected to either the common line 115 or the drain of transistor MN3. As a result, the terminal voltage V SR1 The setting resistor R SET This becomes a fixed voltage at one end. Next, the control circuit 240 sets the reference voltage circuit 120 to a pull-down type (S203). As a result, the power supply voltage V DD The reference voltage V obtained by dividing the voltage REF1 This is generated.

[0131] Next, the control circuit 240 controls the terminal voltage V SR1 The reference voltage V REF1 Determine whether it is greater than or equal to (S205). For example, the setting resistor R SET When the fixed voltage at one end is the ground voltage, the first comparator 232 operates normally, and the first comparator 232 receives a high comparison signal S. CMP1 Generates the setting resistor R. SET A fixed voltage at one end is the power supply voltage V DD If this is the case, the second comparator 234 operates normally, and the second comparator 234 receives a high comparison signal S. CMP2 Generates.

[0132] The control circuit 240 receives the comparison signal S generated by the second comparator 234. CMP2 If the signal is high, the terminal voltage V SR1 The reference voltage V REF1 It can be determined that it is greater than [the specified value]. In addition, the control circuit 240 uses the comparison signal S generated by the first comparator 232. CMP1 If the signal is high, the terminal voltage V SR1 The reference voltage V REF1 It can be determined that it is smaller than the terminal voltage V. SR1 The reference voltage V REF1 If it is determined to be greater than (S205: YES), proceed to S207. Meanwhile, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be smaller than (S205: NO), proceed to S215.

[0133] The control circuit 240 has a terminal voltage V in S205. SR1 The reference voltage V REF1 If it is determined to be greater than, the setting resistor R SET A fixed voltage at one end is the power supply voltage V DD It is determined that (S207). Next, the control circuit 240 sets the switching circuit 114 to a pull-up type (S209). Next, the control circuit 240 sets the reference voltage circuit 120 to a pull-up type (S211). Next, the control circuit 240 determines the comparison result of the second comparator 234 (comparison signal S CMP2 The multiplexer 236 is instructed to select (S213). When the multiplexer 236 selects the comparison result of the second comparator 234, the fixed voltage identification process and the comparator determination process are completed.

[0134] The control circuit 240 has a terminal voltage V in S205. SR1 The reference voltage V REF1 If it is determined to be smaller than, the setting resistor R SET The fixed voltage at one end is identified as the ground voltage (S215). Next, the control circuit 240 sets the switching circuit 114 to a pull-down type (S217). Next, the control circuit 240 uses the comparison result of the first comparator 232 (comparison signal S CMP1The multiplexer 236 is instructed to select (S219). When the multiplexer 236 selects the comparison result of the first comparator 232, the fixed voltage identification process and the comparator determination process are completed.

[0135] (Third embodiment) Figure 14 is a block diagram of system 3 according to the third embodiment. The semiconductor device 30 of system 3 according to the third embodiment mainly uses an A / D converter instead of a comparator to set the resistor R SET Fixed voltage and terminal voltage V at one end SR1 It differs from the semiconductor devices 10 and 20 according to the above embodiment in that it specifies [specific details].

[0136] The semiconductor device 30 according to the third embodiment includes a constant current circuit 100, a first current mirror circuit 104, a direction control circuit 110, an A / D converter 330, a control circuit 340, a DC / DC converter 142, an oscillator 144, a setting terminal SR, and an output terminal OUT.

[0137] The A / D converter 330 has a setting resistor R SET The voltage at the other end (terminal voltage V) SR1 ) to digital signal S ADC Convert to.

[0138] The control circuit 340 receives the digital signal S ADC Based on this, the operation performed by the DC / DC converter 142 is determined. Specifically, the control circuit 340 sets the setting resistor R SET Digital signal S when no current is flowing through it. ADC Based on this, the setting resistor R SET The fixed voltage at one end is identified. Furthermore, the control circuit 340 controls the constant current I CON1 The current corresponding to the set resistor R SET Digital signal S when it is flowing ADC Based on this, terminal voltage V SR1 The control circuit 340 identifies the identified terminal voltage V SR1The DC / DC converter 142 is instructed to perform the associated operation. The control circuit 340 may refer to Table 141 as needed.

[0139] (Fourth Embodiment) Figure 15 is a block diagram of system 4 according to the fourth embodiment. The semiconductor device 40 included in system 4 according to the fourth embodiment mainly provides a constant current I CON2 The size is switchable, and the setting resistor R SET Fixed voltage and constant current I at one end CON2 The current corresponding to the set resistor R SET Terminal voltage V when current flows through it SR2 In addition, constant current I CON2 It differs from the semiconductor devices 10, 20, and 30 according to the above embodiment in that it performs operations associated with [the function].

[0140] The semiconductor device 10 according to the fourth embodiment includes a constant current circuit 400, a first current mirror circuit 104, a direction control circuit 110, a reference voltage circuit 120, a comparator 130, a control circuit 440, a DC / DC converter 442, an oscillator 144, a setting terminal SR, and an output terminal OUT. The semiconductor device 40 includes a setting resistor R SET The system performs an operation corresponding to the set value of the resistance value, and outputs an output voltage V from the output terminal OUT. OUT2 Outputs.

[0141] The constant current circuit 400 according to this embodiment provides a constant current I CON2 Generates a constant current I CON2 The size of the resistor is configured to be switchable. In the constant current circuit 400, a variable resistor R6 is provided in place of the resistor R3 according to the above embodiment. A constant current I is supplied to resistor R6. CON2 When the current flows, a voltage V is present at one end of resistor R6 on the transistor MN1 side. 2- This occurs. Voltage V 2- This is input to the inverting input terminal of the operational amplifier 102.

[0142] The operational amplifier 102 receives the voltage V input to its non-inverting input terminal. 1+ and the voltage V input to the inverting input terminal 2-and are identical (that is, V 1+ =V 2- ) Thus, the output voltage S AMP2 This generates a constant current I CON2 This is expressed by the following equation (8). I CON2 =V DD ×R² / {R⁶×(R⁺R⁶)}···(8)

[0143] By switching the resistance value of resistor R6, a constant current I can be generated according to equation (8). CON2 The magnitude can be switched. Furthermore, by using variable resistors R1 and R2, the voltage division ratio in the voltage divider circuit 101 can be switched to create a constant current I CON2 You can also change the size.

[0144] The comparator 130 according to this embodiment uses a reference voltage V REF1 and the voltage of the setting terminal SR (terminal voltage V SR2 ) is compared with the comparison signal S which shows the comparison result. CMP4 Generates comparison signal S. CMP4 This is input to the control circuit 440.

[0145] The control circuit 440 according to this embodiment includes a setting resistor R SET Fixed voltage and terminal voltage V at one end SR2 In addition, the constant current I generated by the constant current circuit 400 CON2 The DC / DC converter 442 is made to perform the associated operation. The constant current I of different magnitudes is generated by the constant current circuit 400. CON2 This is associated with different operations of the DC / DC converter 442.

[0146] The control circuit 440 according to this embodiment receives a comparison signal S CMP4 Based on this, the setting resistor R SET Fixed voltage at one end, terminal voltage V SR2 and constant current I CON2 A control signal S determines the associated operation and causes the DC / DC converter 442 to execute the determined operation. DC2 Generates.

[0147] The control circuit 440 receives a signal S to switch the switch. SW and signal S for switching resistance values R It can generate the signal S. R This is a signal S for switching the resistance values ​​of resistors R4 and R5 in the reference voltage circuit 120. R1 This also includes a signal R2 for switching the resistance value of resistor R6 in the constant current circuit 400.

[0148] The DC / DC converter 442 receives an input voltage V IN Output voltage V corresponding to the corresponding value OUT2 It generates the DC / DC converter 442, which has a setting resistor R SET Fixed voltage and constant current I at one end CON2 A setting resistor R through which a current corresponding to the current flows. SET The voltage at the other end (terminal voltage V) SR2 In addition to the constant current I generated by the constant current circuit 400 CON2 The DC / DC converter 442 performs the operation associated with it. In this embodiment, the DC / DC converter 442 performs the operation determined by the control circuit 440.

[0149] Figure 16 shows the setting resistor R according to this embodiment. SET The resistance value, setting resistance R SET The method, constant current I CON2 and terminal voltage V SR2 This diagram shows the relationship.

[0150] The resistance value R shown in the top row of Figure 16 11 ~R 14 ,R 21 ~R 24 ,R 31 ~R 34 This embodiment involves the setting resistor R SET These are the possible resistance values ​​R. 11 ~R 14 ,R 21 ~R 24 ,R 31 ~R 34 The larger the subscript, the larger the value. Note that Figure 16 shows 12 setting resistors R. SET This shows the possible resistance values ​​that it can have, but the set resistor RSET The number of resistance values ​​it may have may be 11 or less, or 13 or more.

[0151] In this embodiment, the resistance value R 21 ~R 24 (Second resistance value) is resistance value R 11 ~R 14 It is N times the (first resistance value) (where N is a number greater than 1), and the resistance value R 31 ~R 34 (The third resistance value) is the resistance value R 21 ~R 24 It is N times that. Specifically, N 2 ×R 11 =N×R 21 =R 31 , N 2 ×R 12 =N×R 22 =R 32 , N 2 ×R 13 =N×R 23 =R 33 , N 2 ×R 14 =N×R 24 =R 34 Therefore, N can be, for example, around 10.

[0152] The current values ​​I1 to I3 shown in Figure 16 are constant current I CON2 These are the current values ​​that can be taken. Therefore, the constant current circuit 400 according to this embodiment is a constant current I having any of the current values ​​I1 to I3. CON2 It generates the current values ​​I1 to I3 satisfy I1 > I2 > I3. More specifically, I1 / N 2 =I2 / N=I3. Note that Figure 16 shows three current values ​​I1 to I3, but the constant current I CON2 The number of possible current values ​​may be two or four or more.

[0153] The constant current circuit 400 according to this embodiment includes a setting resistor R SET If the resistance value is the first resistance value, a first constant current is generated, and the setting resistor R SETIf the resistance value of is N times the first resistance value, a second constant current is generated that has a magnitude 1 / N times that of the first constant current. Specifically, the constant current circuit 400 has a setting resistor R SET The resistance value is R 11 ~R 14 In this case, a constant current I with a current value I1 CON2 It generates (the first constant current). The constant current circuit 400 also has a setting resistor R. SET The resistance value is R 21 ~R 24 In this case, a constant current I with current value I2 CON2 (A second constant current) is generated. Furthermore, the constant current circuit 400 has a setting resistor R SET The resistance value is R 31 ~R 34 In this case, a constant current I with a current value I3 CON2 It generates a (third constant current).

[0154] The voltage V shown in Figure 16 D111 ~V D141 ,V D212 ~V D242 ,V D313 ~V D343 ,V U111 ~V U141 ,V U212 ~V U242 ,V U313 ~V U343 These are, respectively, setting resistor R SET The resistance value of is the resistance value of the corresponding column, and constant current I CON2 The terminal voltage V that should occur when the magnitude of V is equal to the current value of the corresponding row SR2 This indicates the voltage V. D111 ~V D141 ,V D212 ~V D242 ,V D313 ~V D343 This is the setting resistor R SET This is the voltage when using a pull-down resistor (pull-down type). Voltage V U111 ~V U141 ,V U212 ~V U242 ,V U313 ~V U343 This is the setting resistor R SET This is the voltage when it is a pull-up resistor (pull-up type). Here, the constant current ICON2 Size and setting resistance R SET Assume that the magnitude of the current flowing through it is the same as that of the current flowing through it.

[0155] In this embodiment, the terminal voltage V to be generated SR2 The setting resistor R is the same SET Resistance value and constant current I CON2 There are multiple combinations of current values. For example, V D111 V D111 =R 11 ×I1. Also, V D212 V D212 =R 21 ×I2=(N×R 11 ) × (I1 / N) = R 11 ×I1=V D111 Furthermore, V D313 V 313 =R 31 ×I3=(N 2 ×R 11 ) × (I1 / N 2 )=R 11 ×I1=V D111 Therefore, V D111 =V D212 =V D313 Similarly, V D121 =V D222 =V D323 , V D131 =V D232 =V D333 , V D141 =V D242 =V D343 Furthermore, V U111 =V U212 =V U313 , V U121 =V U222 =V U323 , V U131 =V U232 =V U333 , V U141 =V U242 =V U343 That is the case.

[0156] In Figure 16, the shaded area is an area unsuitable for associating set values. For example, in the case of a pull-down type, the current value is I1 and the set resistor RSET The resistance value is R 21 In the case of R 21 ×I1>V DD Therefore, the setting resistor R SET Terminal voltage V corresponding to the resistance value SR2 It is not possible to generate it properly.

[0157] Figure 17 shows the constant current I in the pull-down type. CON2 Current values ​​I1~I3 and voltage V of setting terminal SR D111 ~V D141 ,V D212 ~V D242 ,V D313 ~V D343 This figure shows Table 441, which associates the set values. Below, the components of the semiconductor device 40 will be described in more detail with reference to Figure 17.

[0158] As shown in Figure 17, the constant current I generated by the constant current circuit 400 CON2 It contains multiple setting resistors R, each with a different size. SET The voltage at the other end (terminal voltage V) SR2 ) is associated with. In detail, a constant current I with current value I1 is associated with CON2 The voltage V D111 ~V D141 A constant current I with a current value I2 is associated with it. CON2 The voltage V D212 ~V D242 A constant current I with a current value I3 is associated with it. CON2 The voltage V D313 ~V D343 They are associated.

[0159] Voltage V D111 ~V D141 Voltage V D212 ~V D242 Voltage V D313 ~V D343 Different operations are associated with this. Specifically, a constant current I with a current value I1 CON2 The voltage V associated with D111 ~V D141 A setting value of 1 to 4 is associated with this. Also, a constant current I with a current value I2CON2 The voltage V associated with D212 ~V D242 A setting value of 5 to 8 is associated with this. Furthermore, a constant current I with a current value of I3 CON2 The voltage V associated with D313 ~V D343 The setting values ​​9 to 12 are associated with this. Similarly, the voltage V in the pull-up type U111 ~V U141 ,V U212 ~V U242 ,V U313 ~V U343 These settings are associated with settings 13 to 24. Different operations of the DC / DC converter 442 are assigned to these settings 1 to 24. This allows the DC / DC converter 442 to perform 12 different operations.

[0160] The constant current circuit 400 according to this embodiment has a voltage range V that should be generated at the setting terminal SR. RNG3 The upper or lower voltage limit of the reference voltage V REF1 It can be generated as follows. Voltage range V RNG3 This primarily includes voltages associated with a set value and does not include voltages not associated with a set value. The voltage range V according to this embodiment RNG3 Lower limit voltage V MIN3 It is greater than 0V, and the terminal voltage V SR2 It is smaller than the smallest voltage that it can take. Specifically, the voltage V MIN3 In the case of a pull-down menu, 0 <V MIN3 <V D111 It satisfies the following conditions. Also, the voltage V MAX3 In the case of a pull-up resistor, 0 <V MIN3 <V U141 It satisfies the condition.

[0161] Voltage range V according to this embodiment RNG3 The upper limit voltage V MAX3 The terminal voltage V SR2 The voltage is greater than the highest voltage that can be taken, and the power supply voltage V DD It is smaller than. Specifically, the voltage V MAX3 In the case of a pull-down menu, V D141 <VMAX3 <V DD It satisfies the following conditions. Also, the voltage V MAX3 In the case of a pull-up type, V D111 <V MAX3 <V DD It satisfies the condition.

[0162] In this embodiment, the constant current circuit 400 determines the terminal voltage V based on the comparison result of the comparator 130. SR2 The voltage range V that should be generated at the setting terminal SR RNG3 When not inside, terminal voltage V SR2 The voltage range is V RNG3 As shown inside, constant current I CON2 Switch the magnitude. For example, the comparison result of comparator 130 is the terminal voltage V SR2 The voltage range V that should be generated at the setting terminal SR RNG3 When indicating that it is not inside, the terminal voltage V SR2 The voltage range is V RNG3 As shown inside, constant current I CON2 Switch the size.

[0163] The constant current circuit 400 according to this embodiment has a voltage range V to be generated. RNG3 The upper or lower limit of the reference voltage V REF1 Based on the comparison result of comparator 130 when the terminal voltage V is generated, SR2 The voltage range in which it should occur is V RNG3 When not inside, terminal voltage V SR2 The voltage range in which it should occur is V RNG3 As shown inside, constant current I CON2 You can change the size.

[0164] For example, the constant current circuit 400 has a terminal voltage V SR2 The lower limit voltage V MIN3 If the comparison result of comparator 130 indicates that it is smaller than, constant current I CON2 The value may be increased. Also, the constant current circuit 400 has a terminal voltage V SR2 The upper limit voltage V MAX3 If the comparison result of comparator 130 indicates that it is greater than, constant current I CON2 You can make it smaller.

[0165] The constant current circuit 400 adjusts the reference voltage V based on the comparison result of the comparator 130. REF1 The voltage range in which it should occur is V RNG3 With the voltage fixed at the upper or lower limit, the terminal voltage V SR2 The voltage range in which it should occur is V RNG3 As shown inside, constant current I CON2 The magnitude of the constant current circuit 400 can be switched. For example, the reference voltage V REF1 The voltage range in which it should occur is V RNG3 The upper limit voltage V MAX3 With the terminal voltage V fixed, SR2 The upper limit voltage V MAX3 A constant current I is set to be smaller than CON2 You can change the size.

[0166] For example, in the case of a pull-down type, the reference voltage V REF1 The upper limit voltage V MAX3 When this is the case, the terminal voltage V SR2 The reference voltage V REF1 Assume that the comparison result of comparator 130 is greater than . In this case, the constant current circuit 400 is the reference voltage V REF1 The upper limit voltage V MAX3 With the terminal voltage V fixed, SR2 The reference voltage V REF1 Constant current I until it becomes smaller than CON2 You can make it smaller.

[0167] Alternatively, in the case of a pull-down type, the reference voltage V REF1 The lower limit voltage V MIN3 When this is the case, the terminal voltage V SR2 The reference voltage V REF1 Assume that the comparison result of comparator 130 is smaller than the reference voltage V. In this case, the constant current circuit 400 is... REF1 The lower limit voltage V MIN3 With the terminal voltage V fixed, SR2 The reference voltage V REF1 Constant current I until it becomes greater than CON2 You can enlarge it.

[0168] The reference voltage circuit 120 according to this embodiment has a voltage range V to be generated. RNG3 The upper or lower limit of the reference voltage V REF1 It can generate a lower limit voltage V. Specifically, the reference voltage circuit 120 generates a lower limit voltage V. MIN3 or upper voltage V MAX3 The reference voltage V REF1 It can be generated as follows.

[0169] The reference voltage circuit 120 has a lower limit voltage V MIN3 and upper limit voltage V MAX3 In addition, terminal voltage V SR2 Various voltages can be generated to identify the following. For example, the reference voltage circuit 120, in the pull-down type, is V D111 <V DMID1 <V D121 The first intermediate voltage V that satisfies the condition DMID1 , V D121 <V DMID2 <V D131 The second intermediate voltage V that satisfies the condition V DMID2 , V D131 <V DMID3 <V D141 Third intermediate voltage V that satisfies the condition DMID3 The reference voltage V REF1 It can be generated as follows.

[0170] The reference voltage circuit 120, in the case of a pull-up type, V U141 <V UMID1 <V U131 The first intermediate voltage V that satisfies the condition UMID1 , V U131 <V UMID2 <V U121 The second intermediate voltage V that satisfies the condition V UMID2 , and V U121 <V UMID3 <V U111 Third intermediate voltage V that satisfies the condition UMID3 The reference voltage V REF1 It can be generated as follows.

[0171] In this embodiment, the reference voltage circuit 120 calculates the reference voltage V based on the comparison result of the comparator 130. REF1The magnitude of can be switched sequentially. For example, the reference voltage circuit 120 sets the reference voltage V based on the comparison result of the comparator 130. REF1 The size of V MIN3 It may be increased sequentially from there. Alternatively, the reference voltage circuit 120 may set the reference voltage V based on the comparison result of the comparator 130. REF1 The size of V MAX3 You can gradually lower it from there.

[0172] The reference voltage circuit 120 has a terminal voltage V SR1 The voltage range in which it should occur is V RNG3 As shown inside, constant current I CON2 After the magnitude is switched, the reference voltage V REF1 The size can be switched sequentially. This makes it possible to efficiently determine the setting value.

[0173] In this embodiment, the control circuit 440, in the pull-down type, refers to table 441 to determine the operation to be performed by the DC / DC converter 442, and causes the DC / DC converter 442 to perform the determined operation. Specifically, the control circuit 440 controls the constant current I CON2 Determine the magnitude and the determined constant current I CON2 The current corresponding to the set resistor R SET Terminal voltage V when current flows through it SR2 The control circuit 440 controls the operation performed by the DC / DC converter 442 by controlling a constant current I with a determined current value. CON2 and the identified terminal voltage V SR2 The operation assigned to the associated setting value is determined. In the case of a pull-up type, the control circuit 440 may refer to a pull-up type table (not shown) to determine the operation to be performed by the DC / DC converter 442.

[0174] The control circuit 440 according to this embodiment has a terminal voltage V SR2 The voltage range in which it should occur is V RNG3 When the constant current I is inside the constant current circuit 400 CON2 and terminal voltage V SR2Based on this, the operation performed by the DC / DC converter 442 is determined.

[0175] The control circuit 440 according to this embodiment uses a reference voltage V REF1 Based on the comparison results of the comparator 130 in response to the sequential switching of the magnitude, the terminal voltage V SR2 Identify the identified terminal voltage V SR2 The DC / DC converter 442 can be made to perform the associated operation. For example, in the pull-down type, constant current I CON2 When the current value is I1, the terminal voltage V SR2 The first intermediate voltage V DMID1 Larger than the second intermediate voltage V DMID2 Suppose the comparison result of comparator 130 shows that it is smaller than. In this case, control circuit 440 will determine the terminal voltage V SR2 Voltage V D121 Identify that it is the voltage V D121 The DC / DC converter 442 is instructed to perform the action associated with this, i.e., the action assigned to setting value 2.

[0176] Figure 18 is a flowchart showing an example of operation of the semiconductor device 40 according to the fourth embodiment. The operation flow of the semiconductor device 40 will be explained below in accordance with the flowchart shown in Figure 18.

[0177] First, the semiconductor device 40 performs a fixed voltage identification process (S30). This fixed voltage identification process is substantially the same as the fixed voltage identification process (S10) according to the above embodiment, so its explanation is omitted here.

[0178] Next, the semiconductor device 40 performs a constant current determination process (S32). The constant current determination process is performed using the terminal voltage V SR2 The voltage range in which it should occur is V RNG3 As shown inside, constant current I CON2 This is the process of determining the size.

[0179] Next, the semiconductor device 40 executes a process of specifying the terminal voltage (S34). Since this process of specifying the terminal voltage is substantially the same as the process of specifying the terminal voltage (S12) according to the above embodiment, the description thereof is omitted here.

[0180] Next, the semiconductor device 40 executes a control process of the DC / DC converter (S36). The control process of the DC / DC converter is the process of causing the DC / DC converter 442 to execute an operation associated with the fixed voltage at one end of the setting resistor R SET specified in S30, the constant current I CON2 determined in S32, and the terminal voltage V SR2 specified in S34. When the control process of the DC / DC converter is executed, the process shown in FIG. 18 ends.

[0181] FIG. 19 is a flowchart showing an example of the constant current determination process (S32) according to the fourth embodiment. Here, an example of a pull-down type constant current determination process will be described. Hereinafter, the flow of the constant current determination process will be described along the flowchart shown in FIG. 19.

[0182] First, the constant current circuit 400 generates the maximum constant current I CON2 (S321). The constant current circuit 100 may generate a constant current I CON2 having a current value I1. Next, the reference voltage circuit 120 generates the maximum reference voltage V REF1 (S323). The maximum reference voltage V REF1 in S323 may be the upper limit voltage V RNG3 of the voltage range V MAX3 to be generated.

[0183] Next, the comparator 130 determines whether the terminal voltage V SR2 is smaller than the reference voltage V​​​​​​​​​If it is determined that the above is true (S325: NO), proceed to S327.

[0184] In S325, terminal voltage V SR2 The reference voltage V REF1 If it is determined that the above is true, the control circuit 440 will set a constant current I CON2 Reduce (S327). The control circuit 440 controls the constant current I CON2 If the current value is I1, then a constant current I CON2 Reduce the current value to I2, and set the constant current I CON2 If the current value is I2, then constant current I CON2 The current value can be reduced to I3.

[0185] Next, the control circuit 440 outputs a constant current I CON2 It is determined whether or not is the minimum (S329). The control circuit 440 controls the constant current I CON2 If the current value is I3, then the constant current I CON2 It is determined that the constant current I is the minimum. CON2 If the current values ​​are I1 and I2, then a constant current I CON2 It can be determined that it is not the minimum. Constant current I CON2 If it is determined that is the minimum (S329: YES), proceed to S331. Meanwhile, constant current I CON2 If it is determined that the value is not the minimum (S109: NO), the process returns to S323.

[0186] In S325, terminal voltage V SR1 The reference voltage V REF1 If it is determined to be smaller than or constant current I in S329 CON2 When it is determined that the voltage is at its minimum, the control circuit 440 sets the voltage range V that should be generated at the setting terminal SR. RNG3 Terminal voltage V SR2 A constant current I that contains CON2 The magnitude of the constant current I is determined (S331). The control circuit 440 according to this embodiment determines the magnitude of the constant current I generated in the step immediately preceding S331 from among the current values ​​I1 to I3. CON2 The magnitude of the voltage to be generated is the range V RNG3 Terminal voltage V SR2 A constant current I that contains CON2The size is determined. When S331 is completed, the constant current determination process is finished.

[0187] Figure 20 is a flowchart showing an example of the control process (S36) of the DC / DC converter according to the fourth embodiment. The flow of the DC / DC converter control process will be explained below in accordance with the flowchart shown in Figure 20.

[0188] First, the control circuit 440 determines the operation to be performed by the DC / DC converter 442 (S361). The control circuit 440 determines the operation to be performed by the DC / DC converter 442 by setting the resistor R identified in S30. SET A fixed voltage at one end, and a constant current I determined in S32. CON2 and the terminal voltage V identified in S34 SR2 Determine the associated operation. For example, the setting resistor R SET It was determined that the fixed voltage at one end is the ground voltage, and a constant current I CON2 The current is determined to have a current value I1, and the terminal voltage V SR2 Voltage V D121 If this is determined, the control circuit 440 may decide to have the DC / DC converter 442 perform the operation assigned to setting value 2.

[0189] Next, the control circuit 440 causes the DC / DC converter 442 to execute the operation determined in S361 (S363). Once the DC / DC converter 442 executes the determined operation, the control process of the DC / DC converter ends.

[0190] (First variation) In the second embodiment, two comparison signals S are used with the multiplexer 236. CMP21 ,S CMP22 An example of selecting one of the two was explained. However, this is not limited to this example; the control circuit 240 receives a comparison signal S without using the multiplexer 236. CMP21 ,S CMP22 You may allow the user to choose one of the two options.

[0191] (Second variation) In the fourth embodiment, the terminal voltage V is used with the reference voltage circuit 120 and the comparator 130. SR2 An example of identifying the terminal voltage V was explained. However, this is not limited to this example; instead of the reference voltage circuit 120 and comparator 130, the terminal voltage V SR2 An A / D converter may be provided to convert the signal into a digital signal. In this case, the control circuit can determine the operation to be performed by the DC / DC converter 442 based on the digital signal generated by the A / D converter.

[0192] Specifically, the constant current circuit 400 controls the terminal voltage V based on the digital signal generated by the A / D converter. SR2 A constant current I is set so that the voltage is within the range in which it should be generated. CON2 The magnitude is switched. The control circuit switches the terminal voltage V SR2 A constant current I is set so that the voltage is within the range in which it should be generated. CON2 With the magnitude fixed, the terminal voltage V is determined based on the digital signal generated by the A / D converter. SR2 The control circuit identifies the identified terminal voltage V. SR2 The DC / DC converter 442 is instructed to perform the associated operation.

[0193] (Third variation) In the fourth embodiment, in the constant current determination process (S32), the reference voltage V REF1 V MAX3 Fixed to the terminal voltage V SR2 The reference voltage V REF1 Constant current I until it becomes smaller than CON2 By reducing the constant current I CON2 An example of determining the magnitude of V was explained. This is not limited to this example; the reference voltage V REF1 V MIN3 Fixed to the terminal voltage V SR2 The reference voltage V REF1 Constant current I until it becomes greater than CON2 By increasing the constant current I CON2 You may decide on the size.

[0194] (Fourth variation) In the above embodiment, an example was described in which the operating circuit is a DC / DC converter. However, the operating circuit is not limited to this and may be a circuit capable of realizing various functions.

[0195] (Fifth variation) The processes described using the flowchart in the above embodiment do not necessarily have to be performed in the order described. If necessary, multiple steps may be performed in a different order, or multiple steps may be performed in parallel.

[0196] (supplement) While the embodiments described herein have been explained using specific terminology, this explanation is merely illustrative to aid understanding and does not limit the scope of this disclosure or the claims. The scope of the present invention is defined by the claims. Furthermore, not only embodiments but also embodiments, examples, and modifications not described herein are included in the scope of the present invention. It is also possible to combine one or more elements of one embodiment with one or more elements of another embodiment.

[0197] (Note) The technology disclosed herein can be understood in one respect as follows:

[0198] (Item 1) A constant current circuit that generates a constant current, The system includes an operating circuit that performs an operation associated with a fixed voltage at one end of a setting resistor and a voltage at the other end of the setting resistor through which a current corresponding to the constant current flows, The voltage at the other end of the setting resistor is a voltage corresponding to the current flowing through the setting resistor. Different fixed voltages at one end of the setting resistor are associated with different operations of the operating circuit. Semiconductor equipment.

[0199] (Item 2) Each of the different fixed voltages at one end of the setting resistor is associated with the voltage at the other end of a plurality of setting resistors, each having a different magnitude. Each of the voltages at the other end of the plurality of setting resistors, associated with a fixed voltage at one end of the setting resistor, is associated with a different operation. Semiconductor device as described in item 1.

[0200] (Item 3) The system further includes a directional control circuit that controls the direction of the current corresponding to the constant current flowing through the setting resistor. The fixed voltage at one end of the setting resistor is a first fixed voltage or a second fixed voltage greater than the first fixed voltage. The directional control circuit, when the fixed voltage at one end of the setting resistor is the first fixed voltage, sets the direction of the current flowing through the setting resistor to flow from the other end to the one end of the setting resistor, and when the fixed voltage at one end of the setting resistor is the second fixed voltage, sets the direction of the current flowing through the setting resistor to flow from the one end to the other end of the setting resistor. Semiconductor device as described in item 1 or 2.

[0201] (Item 4) A reference voltage circuit that generates a reference voltage and is configured to allow switching of the magnitude of the reference voltage, A comparison circuit including a comparator that compares the reference voltage with the voltage at the other end of the setting resistor, The system further comprises a control circuit for controlling the operation of the aforementioned operating circuit, The control circuit determines the operation to be performed by the operating circuit based on the comparison result of the comparator. Semiconductor device as described in item 3.

[0202] (Item 5) The control circuit identifies a fixed voltage at one end of the setting resistor based on the comparison result of the comparator when no current flows through the setting resistor, identifies a voltage at the other end of the setting resistor based on the comparison result of the comparator when a current corresponding to the constant current flows through the setting resistor, and causes the operating circuit to perform an operation associated with the identified fixed voltage at one end of the setting resistor and the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 4.

[0203] (Item 6) The reference voltage circuit sequentially switches the magnitude of the reference voltage based on the comparison result of the comparator. The control circuit identifies the voltage at the other end of the setting resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 5.

[0204] (Item 7) The reference voltage circuit generates the reference voltage by dividing the voltage difference between the first fixed voltage and the second fixed voltage, and switches the magnitude of the reference voltage by switching the voltage division ratio. A semiconductor device as described in any one of items 4 through 6.

[0205] (Item 8) The comparison circuit includes a first comparator configured to operate normally when the input voltage is within a first voltage range, and a second comparator configured to operate normally when the input voltage is within a second voltage range. The lower limit voltage of the first voltage range is less than or equal to the first fixed voltage. The upper limit voltage of the first voltage range is less than the second fixed voltage. The lower limit voltage of the second voltage range is greater than the first fixed voltage. The upper limit voltage of the second voltage range is greater than or equal to the second fixed voltage. The first comparator and the second comparator each compare the reference voltage with the voltage at the other end of the setting resistor, The control circuit, when the fixed voltage at one end of the setting resistor is the first fixed voltage, identifies the voltage at the other end of the setting resistor based on the comparison result of the first comparator; when the fixed voltage at one end of the setting resistor is the second fixed voltage, identifies the voltage at the other end of the setting resistor based on the comparison result of the second comparator; and causes the operating circuit to perform an operation associated with the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 4.

[0206] (Item 9) The circuit further comprises a first current mirror circuit that copies the constant current, The directional control circuit includes a second current mirror circuit that copies the current generated by the first current mirror circuit by copying the constant current, and a switching circuit configured to switch the current flowing through the setting resistor between the current generated by the first current mirror circuit and the current generated by the second current mirror circuit. The switching circuit, by passing the current generated by the first current mirror circuit through the setting resistor, directs the current flowing through the setting resistor from one end to the other, and by passing the current generated by the second current mirror circuit through the setting resistor, directs the current flowing through the setting resistor from one end to the other. A semiconductor device as described in any one of items 3 through 8.

[0207] (Item 10) The first fixed voltage is the ground voltage, The aforementioned second fixed voltage is the power supply voltage, The first current mirror circuit is composed of two P-channel type MOS transistors. The power supply voltage is applied to the source of each of the two P-channel type MOS transistors. Semiconductor device as described in item 9.

[0208] (Item 11) The constant current circuit includes a voltage divider circuit for dividing the power supply voltage, an operational amplifier, a MOS transistor, and a resistor provided between the MOS transistor and ground. The MOS transistor is provided such that the output signal of the operational amplifier is received at the gate and the constant current flows through it. The voltage generated by the voltage divider circuit by dividing the power supply voltage is input to the non-inverting input terminal of the operational amplifier. The voltage at one end of the resistor on the MOS transistor side is input to the inverting input terminal of the operational amplifier. Semiconductor device as described in item 10.

[0209] (Item 12) An A / D converter that converts the voltage at the other end of the aforementioned setting resistor into a digital signal, The system further comprises a control circuit that determines the operation performed by the operating circuit based on the aforementioned digital signal, The control circuit identifies a fixed voltage at one end of the setting resistor based on the digital signal when no current is flowing through the setting resistor, identifies a voltage at the other end of the setting resistor based on the digital signal when a current corresponding to the constant current is flowing through the setting resistor, and causes the operating circuit to perform an operation associated with the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 3.

[0210] (Item 13) The constant current circuit is configured to allow switching of the magnitude of the constant current. The operating circuit performs operations associated with the constant current generated by the constant current circuit, in addition to the fixed voltage at one end of the setting resistor and the voltage at the other end of the setting resistor through which a current corresponding to the constant current flows. Different constant currents of different magnitudes generated by the constant current circuit are associated with different operations of the operating circuit. Semiconductor device as described in item 1.

[0211] (Item 14) The constant current generated by the constant current circuit is associated with the voltage at the other end of a plurality of setting resistors, each having a different magnitude. Different operations are associated with the voltages at the other ends of the plurality of setting resistors associated with the constant current. Semiconductor device as described in item 13.

[0212] (Item 15) The system further includes a control circuit for controlling the operation of the aforementioned operating circuit, The constant current circuit switches the magnitude of the constant current so that the voltage at one end of the setting resistor is within the range of the voltage that should be generated at the other end of the setting resistor when the voltage at one end of the setting resistor is not within the range of the voltage that should be generated. The control circuit determines the operation to be performed by the operating circuit based on the constant current generated by the constant current circuit and the voltage at the other end of the setting resistor, when the voltage at the other end of the setting resistor is within the range of the voltage to be generated. The aforementioned operating circuit executes the operation determined by the control circuit. Semiconductor device as described in item 14.

[0213] (Item 16) A reference voltage circuit that generates a reference voltage and is configured to allow switching of the magnitude of the reference voltage, The system further comprises a comparator that compares the reference voltage with the voltage at the other end of the setting resistor. The control circuit determines the operation to be performed by the operating circuit based on the comparison result of the comparator. Semiconductor device as described in item 15.

[0214] (Item 17) The aforementioned reference voltage circuit generates a reference voltage that is the upper or lower limit of the voltage range to be generated. The constant current circuit, based on the comparison result of the comparator when the upper or lower reference voltage is generated, switches the magnitude of the constant current so that the voltage at one end of the setting resistor is within the range of the voltage to be generated when the voltage at the other end of the setting resistor is not within the range of the voltage to be generated. Semiconductor device as described in item 16.

[0215] (Item 18) The constant current circuit switches the magnitude of the constant current based on the comparison result of the comparator so that the voltage at the other end of the set resistor is within the range of the voltage to be generated. The reference voltage circuit sequentially switches the magnitude of the reference voltage based on the comparison result of the comparator. The control circuit identifies the voltage at the other end of the setting resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 17.

[0216] (Item 19) The constant current circuit, based on the comparison result of the comparator, switches the magnitude of the constant current so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated, while the reference voltage is fixed at the upper or lower limit voltage. The reference voltage circuit, after the magnitude of the constant current has been switched so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated, sequentially switches the magnitude of the reference voltage. The control circuit identifies the voltage at the other end of the setting resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 17.

[0217] (Item 20) The aforementioned reference voltage circuit generates the reference voltage by dividing the power supply voltage, and the magnitude of the reference voltage is switched by switching the voltage division ratio. A semiconductor device as described in any one of items 16 to 19.

[0218] (Item 21) The system further includes an A / D converter that converts the voltage at the other end of the aforementioned setting resistor into a digital signal. The control circuit determines the operation to be performed by the operating circuit based on the digital signal. Semiconductor device as described in item 15.

[0219] (Item 22) The constant current circuit switches the magnitude of the constant current based on the digital signal generated by the A / D converter, such that the voltage at the other end of the setting resistor is within the range of the voltage to be generated. The control circuit, with the magnitude of the constant current fixed so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated, identifies the voltage at the other end of the setting resistor based on the digital signal generated by the A / D converter, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. Semiconductor device as described in item 21.

[0220] (Item 23) The constant current circuit generates a first constant current when the resistance value of the set resistor is a first resistance value, and generates a second constant current having a magnitude of 1 / N times the first constant current when the resistance value of the set resistor is a second resistance value that is N times the first resistance value (where N is a number greater than 1). A semiconductor device as described in any one of items 13 through 22.

[0221] (Item 24) The constant current circuit includes a voltage divider circuit for dividing the power supply voltage, an operational amplifier, a MOS transistor, and a resistor provided between the MOS transistor and ground. The MOS transistor is provided such that the output signal of the operational amplifier is received at the gate and the constant current flows through it. The voltage generated by the voltage divider circuit by dividing the power supply voltage is input to the non-inverting input terminal of the operational amplifier. The voltage at one end of the resistor on the MOS transistor side is input to the inverting input terminal of the operational amplifier. A semiconductor device as described in any one of items 13 through 23.

[0222] (Item 25) The system further comprises a current mirror circuit that copies the constant current generated by the constant current circuit, A current corresponding to the current copied by the current mirror circuit flows through the aforementioned setting resistor. A semiconductor device as described in any one of items 13 through 24.

[0223] (Item 26) The aforementioned operating circuit is a DC / DC converter. A semiconductor device as described in any one of items 1 through 25. [Explanation of Symbols]

[0224] 1,2,3,4 System, 10,20,30,40 Semiconductor device, 100,400 Constant current circuit, 101 Voltage divider circuit, 102 Operational amplifier, 104 First current mirror circuit, 110 Directional control circuit, 112 Second current mirror circuit, 114 Switching circuit, 115 Common line, 120 Reference voltage circuit, 130 Comparator, 140,240,340,440 Control circuit, 142,442 DC / DC converter, 144 Oscillator, 230 Comparison circuit, 232 First comparator, 234 Second comparator, 236 Multiplexer, 330 A / D converter, R SET Setting resistors, R1~R6 resistors, MP1, MP2, MN1~MN3 transistors, SW1 first switch, SW2 second switch, SW3 third switch, SW4 fourth switch, SW5 fifth switch, SW6 sixth switch.

Claims

1. A constant current circuit that generates a constant current, The system includes an operating circuit that performs an operation associated with a fixed voltage at one end of a setting resistor and a voltage at the other end of the setting resistor through which a current corresponding to the constant current flows, The voltage at the other end of the setting resistor is a voltage corresponding to the current flowing through the setting resistor. Different fixed voltages at one end of the setting resistor are associated with different operations of the operating circuit. Semiconductor equipment.

2. Each of the different fixed voltages at one end of the setting resistor is associated with the voltage at the other end of a plurality of setting resistors, each having a different magnitude. Each of the voltages at the other end of the plurality of setting resistors, associated with a fixed voltage at one end of the setting resistor, is associated with a different operation. The semiconductor device according to claim 1.

3. The system further includes a directional control circuit that controls the direction of the current corresponding to the constant current flowing through the setting resistor. The fixed voltage at one end of the setting resistor is a first fixed voltage or a second fixed voltage greater than the first fixed voltage. The directional control circuit, when the fixed voltage at one end of the setting resistor is the first fixed voltage, sets the direction of the current flowing through the setting resistor to flow from the other end to the one end of the setting resistor, and when the fixed voltage at one end of the setting resistor is the second fixed voltage, sets the direction of the current flowing through the setting resistor to flow from the one end to the other end of the setting resistor. The semiconductor device according to claim 1.

4. A reference voltage circuit that generates a reference voltage and is configured to allow switching of the magnitude of the reference voltage, A comparison circuit including a comparator that compares the reference voltage with the voltage at the other end of the setting resistor, The system further comprises a control circuit for controlling the operation of the aforementioned operating circuit, The control circuit determines the operation to be performed by the operating circuit based on the comparison result of the comparator. The semiconductor device according to claim 3.

5. The control circuit identifies a fixed voltage at one end of the setting resistor based on the comparison result of the comparator when no current flows through the setting resistor, identifies a voltage at the other end of the setting resistor based on the comparison result of the comparator when a current corresponding to the constant current flows through the setting resistor, and causes the operating circuit to perform an operation associated with the identified fixed voltage at one end of the setting resistor and the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 4.

6. The reference voltage circuit sequentially switches the magnitude of the reference voltage based on the comparison result of the comparator. The control circuit identifies the voltage at the other end of the setting resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 5.

7. The reference voltage circuit generates the reference voltage by dividing the voltage difference between the first fixed voltage and the second fixed voltage, and switches the magnitude of the reference voltage by switching the voltage division ratio. The semiconductor device according to claim 4.

8. The comparison circuit includes a first comparator configured to operate normally when the input voltage is within a first voltage range, and a second comparator configured to operate normally when the input voltage is within a second voltage range. The lower limit voltage of the first voltage range is less than or equal to the first fixed voltage. The upper limit voltage of the first voltage range is less than the second fixed voltage. The lower limit voltage of the second voltage range is greater than the first fixed voltage. The upper limit voltage of the second voltage range is greater than or equal to the second fixed voltage. The first comparator and the second comparator each compare the reference voltage with the voltage at the other end of the setting resistor, The control circuit, when the fixed voltage at one end of the setting resistor is the first fixed voltage, identifies the voltage at the other end of the setting resistor based on the comparison result of the first comparator; when the fixed voltage at one end of the setting resistor is the second fixed voltage, identifies the voltage at the other end of the setting resistor based on the comparison result of the second comparator; and causes the operating circuit to perform an operation associated with the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 4.

9. The circuit further comprises a first current mirror circuit that copies the constant current, The directional control circuit includes a second current mirror circuit that copies the current generated by the first current mirror circuit by copying the constant current, and a switching circuit configured to switch the current flowing through the setting resistor between the current generated by the first current mirror circuit and the current generated by the second current mirror circuit. The switching circuit, by passing the current generated by the first current mirror circuit through the setting resistor, directs the current flowing through the setting resistor from one end to the other, and by passing the current generated by the second current mirror circuit through the setting resistor, directs the current flowing through the setting resistor from one end to the other. The semiconductor device according to claim 3.

10. The first fixed voltage is the ground voltage, The aforementioned second fixed voltage is the power supply voltage, The first current mirror circuit is composed of two P-channel type MOS transistors. The power supply voltage is applied to the source of each of the two P-channel type MOS transistors. The semiconductor device according to claim 9.

11. The constant current circuit includes a voltage divider circuit for dividing the power supply voltage, an operational amplifier, a MOS transistor, and a resistor provided between the MOS transistor and ground. The MOS transistor is provided such that the output signal of the operational amplifier is received at the gate and the constant current flows through it. The voltage generated by the voltage divider circuit by dividing the power supply voltage is input to the non-inverting input terminal of the operational amplifier. The voltage at one end of the resistor on the MOS transistor side is input to the inverting input terminal of the operational amplifier. The semiconductor device according to claim 10.

12. An A / D converter that converts the voltage at the other end of the aforementioned setting resistor into a digital signal, The system further comprises a control circuit that determines the operation performed by the operating circuit based on the aforementioned digital signal, The control circuit identifies a fixed voltage at one end of the setting resistor based on the digital signal when no current is flowing through the setting resistor, identifies a voltage at the other end of the setting resistor based on the digital signal when a current corresponding to the constant current is flowing through the setting resistor, and causes the operating circuit to perform an operation associated with the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 3.

13. The constant current circuit is configured to allow switching of the magnitude of the constant current. The operating circuit performs operations associated with the constant current generated by the constant current circuit, in addition to the fixed voltage at one end of the setting resistor and the voltage at the other end of the setting resistor through which a current corresponding to the constant current flows. Different constant currents of different magnitudes generated by the constant current circuit are associated with different operations of the operating circuit. The semiconductor device according to claim 1.

14. The constant current generated by the constant current circuit is associated with the voltage at the other end of a plurality of setting resistors, each having a different magnitude. Different operations are associated with the voltages at the other ends of the plurality of setting resistors associated with the constant current. The semiconductor device according to claim 13.

15. The system further includes a control circuit for controlling the operation of the aforementioned operating circuit, The constant current circuit switches the magnitude of the constant current so that the voltage at one end of the setting resistor is within the range of the voltage that should be generated at the other end of the setting resistor when the voltage at one end of the setting resistor is not within the range of the voltage that should be generated. The control circuit determines the operation to be performed by the operating circuit based on the constant current generated by the constant current circuit and the voltage at the other end of the setting resistor, when the voltage at the other end of the setting resistor is within the range of the voltage to be generated. The aforementioned operating circuit executes the operation determined by the control circuit. The semiconductor device according to claim 14.

16. A reference voltage circuit that generates a reference voltage and is configured to allow switching of the magnitude of the reference voltage, The system further comprises a comparator that compares the reference voltage with the voltage at the other end of the setting resistor. The control circuit determines the operation to be performed by the operating circuit based on the comparison result of the comparator. The semiconductor device according to claim 15.

17. The aforementioned reference voltage circuit generates a reference voltage that is the upper or lower limit of the voltage range to be generated. The constant current circuit, based on the comparison result of the comparator when the upper or lower reference voltage is generated, switches the magnitude of the constant current so that the voltage at one end of the setting resistor is within the range of the voltage to be generated when the voltage at the other end of the setting resistor is not within the range of the voltage to be generated. The semiconductor device according to claim 16.

18. The constant current circuit switches the magnitude of the constant current based on the comparison result of the comparator so that the voltage at the other end of the set resistor is within the range of the voltage to be generated. The reference voltage circuit sequentially switches the magnitude of the reference voltage based on the comparison result of the comparator. The control circuit identifies the voltage at the other end of the setting resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 17.

19. The constant current circuit, based on the comparison result of the comparator, switches the magnitude of the constant current so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated, while the reference voltage is fixed at the upper or lower limit voltage. The reference voltage circuit, after the magnitude of the constant current has been switched so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated, sequentially switches the magnitude of the reference voltage. The control circuit identifies the voltage at the other end of the setting resistor based on the comparison result of the comparator corresponding to the sequential switching of the magnitude of the reference voltage, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 17.

20. The aforementioned reference voltage circuit generates the reference voltage by dividing the power supply voltage, and the magnitude of the reference voltage is switched by switching the voltage division ratio. The semiconductor device according to claim 16.

21. The system further includes an A / D converter that converts the voltage at the other end of the aforementioned setting resistor into a digital signal. The control circuit determines the operation to be performed by the operating circuit based on the digital signal. The semiconductor device according to claim 15.

22. The constant current circuit switches the magnitude of the constant current based on the digital signal generated by the A / D converter so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated. The control circuit, with the magnitude of the constant current fixed so that the voltage at the other end of the setting resistor is within the range of the voltage to be generated, identifies the voltage at the other end of the setting resistor based on the digital signal generated by the A / D converter, and causes the operating circuit to perform the operation associated with the identified voltage at the other end of the setting resistor. The semiconductor device according to claim 21.

23. The constant current circuit generates a first constant current when the resistance value of the set resistor is a first resistance value, and generates a second constant current having a magnitude of 1 / N times the first constant current when the resistance value of the set resistor is a second resistance value that is N times the first resistance value (where N is a number greater than 1). The semiconductor device according to any one of claims 13 to 22.

24. The constant current circuit includes a voltage divider circuit for dividing the power supply voltage, an operational amplifier, a MOS transistor, and a resistor provided between the MOS transistor and ground. The MOS transistor is provided such that the output signal of the operational amplifier is received at the gate and the constant current flows through it. The voltage generated by the voltage divider circuit by dividing the power supply voltage is input to the non-inverting input terminal of the operational amplifier. The voltage at one end of the resistor on the MOS transistor side is input to the inverting input terminal of the operational amplifier. The semiconductor device according to claim 15.

25. The system further comprises a current mirror circuit that copies the constant current generated by the constant current circuit, A current corresponding to the current copied by the current mirror circuit flows through the aforementioned setting resistor. The semiconductor device according to claim 13.

26. The aforementioned operating circuit is a DC / DC converter. The semiconductor device according to claim 1.

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