Voltage detector

Abstract

To provide a voltage detector with reduced power consumption. [Solution] A transistor M3 is provided between resistors R1 and R2, with its source connected to the gate of transistor M1 and its gate connected to the source of transistor M1. A transistor M4 is connected in series with resistors R1 and R2, interrupting the current flowing through resistors R1 and R2. A voltage clamp element 61 is connected between the input terminal T1 to which the input voltage VS is supplied and the gate of transistor M4. A constant current source 92 is connected between the gate of transistor M4 and the other end of resistor R2.

Description

[Technical Field]

[0001] This invention relates to a voltage detector. [Background technology]

[0002] Global warming is thought to be caused by an increase in the concentration of greenhouse gases such as CO2, which strengthens the greenhouse effect in the atmosphere. With the rapid progress of the information and communication society, reducing the power consumption of electronic devices has become a major challenge. Many semiconductor integrated circuits are used in electronic devices, and this invention aims to reduce the current consumption of voltage detectors, which are widely used in semiconductor integrated circuits, and thereby contribute to mitigating global warming.

[0003] Conventionally, a circuit like the one shown in Figure 6 is known as a voltage detector used in semiconductor integrated circuits (see, for example, Patent Documents 1 and 2). The conventional voltage detector 100 shown in Figure 6 is mainly composed of a resistive voltage divider unit 102 that outputs a divided voltage based on the input voltage, a differential input unit 103, an output unit 104, and an output buffer unit 105.

[0004] The resistive voltage divider 102 has resistors R1 and R2 connected in series between the input terminal T1 to which the input voltage VS is input and the negative power supply terminal to which the negative power supply voltage VSS is supplied. The resistive voltage divider 102 outputs a divided voltage VA (voltage generated at junction node A) from the connection point (junction node A) between resistors R1 and R2. The divided voltage VA changes based on the voltage VS input to the input terminal T1.

[0005] The differential input section 103 consists of transistors M1 and M2, whose sources are connected in common and through which currents flow in a current ratio corresponding to the potential difference between the reference voltage VREF generated by the reference voltage source 31 and the divided voltage VA, respectively, and a constant current source 90 connected between the common source of transistors M1 and M2 and the positive power supply terminal to which the positive power supply voltage VDD is supplied.

[0006] The output section 104 consists of a transistor M11 connected in series with transistor M1, a transistor M12 connected in series with transistor M2, a transistor M13 whose gate is connected to the connection point between transistors M1 and M11 and whose source is connected to the negative power supply terminal, and a constant current source 91 connected between the drain of transistor M13 and the positive power supply terminal.

[0007] Transistor M12 has its gate and drain connected to the drain of transistor M2, and its source connected to the negative power supply terminal. Transistor M11 has its drain connected to the drain of transistor M1, its source connected to the negative power supply terminal, and its gate connected to the gate and drain of transistor M12. In other words, transistor M11 is current-mirror connected to transistor M12, copying and folding back the current flowing through transistor M12.

[0008] The output buffer section 105 consists of two inverters 51 and 52. Inverter 51 has its input connected to the connection point between transistor M13 and constant current source 91, and its output connected to the input of inverter 52. Inverter 52 has its output connected to output terminal T3 and outputs the output signal VOUT.

[0009] In the operation of a conventional voltage detector 100 to detect low voltage, if the input voltage VS is high and the divided voltage VA is higher than the reference voltage VREF, the output unit 104 outputs a High potential and the output signal VOUT becomes a High potential. This state is called the deactivated state of the voltage detector. If the input voltage VS is low and the divided voltage VA is lower than the reference voltage VREF, the output unit 104 outputs a Low potential and the output signal VOUT becomes a Low potential. This state is called the detected state of the voltage detector, and the detection voltage V when the output signal VOUT transitions from a High potential to a Low potential is called the detection voltage V DET This is represented by Equation 1.

[0010]

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[0011] Here, R1 is the resistance value of the resistor R1, and R2 is the resistance value of the resistor R2.

[0012] Next, an operation in which current consumption increases as the input voltage VS rises will be described. The current IS flowing to the input terminal T1 (resistive voltage divider 102) is expressed by Equation 2.

[0013] [Equation]

[0014] From Equation 2, the current IS flowing to the input terminal T1 increases in proportion to the rise of the input voltage VS. Therefore, when the input voltage VS is high, the current IS flowing to the resistive voltage divider 102 becomes large, and the current consumption also increases. In addition, if the resistance values of the resistors R1 and R2 are increased, the current IS flowing to the input terminal T1 can be reduced, but the chip size becomes larger, leading to an increase in manufacturing cost.

[0015] The conventional voltage detector 100 described above has a problem that current consumption increases because the current IS flowing to the input terminal T1 increases in accordance with the input voltage VS. [Prior Art Documents] [Patent Documents]

[0016] [Patent Document 1] Japanese Patent No. 7131965 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2004-198335 [Summary of the Invention] [Problem to be Solved by the Invention]

[0017] The present invention has been made in view of the above circumstances, and an object thereof is to provide a voltage detector with reduced current consumption. [Means for Solving the Problem]

[0018] To achieve the aforementioned objectives, the voltage detector according to the present invention is characterized by the following [1] to

[10] . [1] A resistive voltage divider having a first resistor and a second resistor that divide the input voltage, A differential input unit having a first transistor to which a divided voltage obtained by dividing the input voltage is supplied to the gate or base, and a second transistor to which a reference voltage is supplied to the gate or base, which generates a differential current with a current ratio corresponding to the difference between each gate voltage or each base voltage, A voltage detector comprising an output unit that generates a voltage corresponding to the current difference of the differential current, The resistor voltage divider is provided between the first resistor and the second resistor, and further comprises a third transistor whose source or emitter is connected to the gate or base of the first transistor, and whose gate or base is connected to the source or emitter of the first transistor. It is a voltage detector. [2] In the voltage detector described in [1], The resistor voltage divider further includes a switch element connected in series with the first resistor and the second resistor, which interrupts the current flowing through the first resistor and the second resistor. It is a voltage detector. [3] In the voltage detector described in [2], The aforementioned switch element is The source-drain or emitter-collector connection is made up of a fourth transistor connected between the gate or base of the first transistor and one end of the second resistor. It is a voltage detector. [4] In the voltage detector described in [3], The voltage divider ratio control unit further comprises a voltage clamping element connected between an input terminal to which the input voltage is supplied and the gate or base of the fourth transistor, The resistor voltage divider further comprises a current source connected between the gate or base of the fourth transistor and the other end of the second resistor. It is a voltage detector. [5] In the voltage detector described in [4], The first resistor is composed of a first divider resistor and a second divider resistor connected in series. The voltage divider ratio control unit has a fifth transistor whose source-drain or emitter-collector is connected between the input terminal and the voltage clamp element, and whose gate or base is connected to the connection point between the first divider resistor and the second divider resistor. It is a voltage detector. [6] In the voltage detector described in [4], The voltage divider ratio control unit further comprises a sixth transistor whose source-drain or emitter-collector is connected between the voltage clamping element and the current source, and whose gate or base is connected to the gate or base of the first transistor. It is a voltage detector. [7] A resistive voltage divider having a first resistor and a second resistor that divide the input voltage, A differential input unit having a first transistor to which a divided voltage obtained by dividing the input voltage is supplied to the gate or base, and a second transistor to which a reference voltage is supplied to the gate or base, which generates a differential current with a current ratio corresponding to the difference between each gate voltage or each base voltage, A voltage detector comprising an output unit that generates a voltage corresponding to the current difference of the differential current, The resistor voltage divider is provided between the first resistor and the second resistor, and further comprises a third transistor which is composed of a depletion-type electrolytic effect transistor whose source is connected to the gate or base of the first transistor and to which the reference voltage is supplied to the gate. It is a voltage detector. [8] In the voltage detector described in [2], When the switch element is off, the circuit currents of the differential input and output sections are interrupted. It is a voltage detector. [9] In the voltage detector described in any one of items [1] to [8], At least one of the aforementioned transistors is composed of bipolar transistors. Voltage detector.

[10] In the voltage detector described in any one of items [1] to [8], At least one of the aforementioned transistors is composed of an electrolytic effect transistor. It is a voltage detector. [Effects of the Invention]

[0019] The voltage detector according to the present invention has the effect of reducing current consumption.

[0020] The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by referring to the attached drawings and reading through the embodiments for carrying out the invention described below (hereinafter referred to as "embodiments"). [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a circuit diagram showing a voltage detector in the first embodiment. [Figure 2] Figure 2 shows the current characteristics flowing through the resistive voltage divider unit 2 and the voltage divider ratio control unit 6 in the first embodiment. [Figure 3] Figure 3 is a circuit diagram showing a voltage detector in the second embodiment. [Figure 4] Figure 4 shows the current characteristics flowing through the resistive voltage divider 2B and the voltage divider ratio control unit 6B in the second embodiment. [Figure 5] Figure 5 is a circuit diagram showing a voltage detector in the third embodiment. [Figure 6] Figure 6 is a circuit diagram showing an example of a conventional voltage detector. [Modes for carrying out the invention]

[0022] Specific embodiments of the present invention will be described below with reference to the figures.

[0023] (First Embodiment) First, the voltage detector 1 of the first embodiment will be described with reference to Figure 1. As shown in the figure, the voltage detector 1 includes a resistive voltage divider unit 2, a differential input unit 3, an output unit 4, an output buffer unit 5, and a voltage divider ratio control unit 6.

[0024] The resistive voltage divider 2 supplies the divided voltage of the input voltage VS to the differential input 3. The resistive voltage divider 2 consists of resistors R1 (=first resistor), R2 (=second resistor), transistor M3 (=third transistor), and transistor M4 (=switch element, fourth transistor) connected in series between the input terminal T1 to which the input voltage VS is input and the negative power supply terminal T21, and a constant current source 92 (=current source) connected between the gate of transistor M4 and the negative power supply terminal T21. The negative power supply voltage VSS is supplied to the negative power supply terminal T21.

[0025] Transistor M3 is composed of an N-channel field-effect transistor. Transistor M4 is composed of a P-channel field-effect transistor. Resistor R1 is connected between the input terminal T1 and the drain of transistor M3. The gate of transistor M3 is connected to the sources of transistors M1 and M2, which will be described later, and the source of transistor M3 is connected to the source of transistor M4. Resistor R2 is connected between the drain of transistor M4 and the negative power supply terminal T21.

[0026] The resistive voltage divider 2 outputs a divided voltage VA (voltage generated at junction node A) based on the input voltage VS from the connection point (junction node A) between the source of transistor M3 and the source of transistor M4.

[0027] The differential input section 3 consists of transistors M1 and M2, whose sources are connected in common and through which currents flow in a ratio corresponding to the potential difference between the reference voltage VREF generated by the reference voltage source 31 and the divided voltage VA, respectively, and a constant current source 90 connected between the common source of transistors M1 and M2 and the positive power supply terminal T22. The positive power supply voltage VDD is supplied to the positive power supply terminal T22.

[0028] Transistors M1 and M2 are composed of P-channel field-effect transistors. Node A is connected to the gate of transistor M1, and a voltage divider voltage VA is supplied to it. Reference voltage source 31 is connected to the gate of transistor M2, and a reference voltage VREF is supplied to it. The constant current supplied by the constant current source 90 is divided between transistors M1 and M2. The current ratio (divide ratio) of the currents flowing through transistors M1 and M2 is a value corresponding to the reference voltage VREF and the voltage divider voltage VA.

[0029] The differential input unit 3 compares the reference voltage VREF generated by the reference voltage source 31 with the divided voltage VA generated by the resistive voltage divider unit 2, and generates a differential current with a current ratio corresponding to the comparison result.

[0030] In this embodiment, the output section 4 is composed of a transistor M11 connected in series with transistor M1, a transistor M12 connected in series with transistor M2, a transistor M13 whose gate is connected to the connection point between transistors M1 and M11 and whose source is connected to the negative power supply terminal T21, and a constant current source 91 connected between the drain of transistor M13 and the positive power supply terminal T22. Transistors M11, M12, and M13 are composed of N-channel field-effect transistors.

[0031] Transistor M12 has its gate and drain connected to the drain of transistor M2, and its source connected to the negative power supply terminal T21. Transistor M11 has its drain connected to the drain of transistor M1, its source connected to the negative power supply terminal T21, and its gate connected to the gate and drain of transistor M12. In other words, transistor M11 is current-mirror connected to transistor M12, copying and folding back the current flowing through transistor M12.

[0032] In this embodiment, the output buffer unit 5 is composed of two inverters 51 and 52. The input of inverter 51 is connected to the connection point between transistor M13 and constant current source 91, and its output is connected to the input of inverter 52. The output of inverter 52 is connected to output terminal T3 and outputs the output signal VOUT.

[0033] The voltage divider ratio control unit 6 consists of a voltage clamping element 61 connected between the input terminal T1 and the gate of transistor M4. The voltage clamping element 61 allows current to pass through when a voltage exceeding a predetermined level is applied between its terminals, thereby limiting the voltage between terminals to a constant level even if the current changes. The voltage clamping element 61 is composed of a constant voltage diode or multiple diode-connected transistors, etc.

[0034] Next, the operation of the voltage detector 1 with the above configuration will be described below. First, we will describe the operation in the detection state where the divided voltage VA is lower than the reference voltage VREF and the output of output terminal T3 is at a low potential, that is, the output signal VOUT is approximately the negative power supply voltage VSS.

[0035] When the divided voltage VA is lower than the reference voltage VREF, more current flows from the constant current source 90 to transistor M1 than to transistor M2. Because transistor M11 is current mirrored to transistor M12, the gate voltage of transistor M13 rises.

[0036] As the gate voltage of transistor M13 increases, the drain current of transistor M13 increases and becomes greater than the current of the constant current source 91. The input of inverter 51 becomes low, and the output signal VOUT becomes low.

[0037] Next, we will explain the operation in the release state where the divided voltage VA is higher than the reference voltage VREF, and the output of output terminal T3 is at a high potential, i.e., the output signal VOUT is approximately the positive power supply voltage VDD.

[0038] When the divided voltage VA is higher than the reference voltage VREF, more current flows from the constant current source 90 to transistor M2 than to transistor M1. Because transistor M11 is current mirrored to transistor M12, the gate voltage of transistor M13 decreases.

[0039] As the gate voltage of transistor M13 decreases, the drain current of transistor M13 decreases and becomes smaller than the current of the constant current source 91. The input of inverter 51 becomes high potential, and the output signal VOUT becomes high potential.

[0040] Next, the current IS flowing through the input terminal T1 (resistive voltage divider unit 2 and voltage divider ratio control unit 6) will be explained below with reference to the current characteristics shown in Figure 2.

[0041] In region D1, where the input voltage VS is represented by Equation 3, the voltage clamp element is in the off state and transistor M4 is in the on state. Also, in region D1, the input voltage VS is low, i.e., the source voltage of transistor M3 is low, so the gate-source voltage of transistor M3 is above the threshold voltage of transistor M3. Therefore, the drain-source voltage of transistor M3 becomes almost zero, and the divided voltage VA is the voltage divided by resistors R1 and R2. The divided voltage VA changes according to the voltage VS input to input terminal T1, and the current IS flowing through input terminal T1 is represented by Equation 5.

[0042]

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[0043]

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[0044]

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[0045] Here, R1 is the resistance value of resistor R1, R2 is the resistance value of resistor R2, V GS2 V is the gate-source voltage of transistor M2. TH3 This is the threshold voltage of transistor M3.

[0046] From Equation 5, in region D1 of Equation 3, when the input voltage VS is low, the current IS flowing through the input terminal T1 fluctuates in proportion to the input voltage VS, but because the input voltage VS is low, the current IS flowing through the input terminal T1 is small. Note that the voltage VS1 shown in Equation 3 is the same as the detection voltage V shown in Equation 1 explained in the background art. DET It is provided in a larger size than that.

[0047] When the input voltage VS rises and reaches region D2 in equation 6, the source voltage of transistor M3 rises, the gate-source voltage drops, and the threshold voltage V TH3 This becomes equal to the threshold voltage V. Transistor M3 has a gate-source voltage that is equal to the threshold voltage V. TH3 Below this level, current can no longer flow. Therefore, transistor M3 will not be able to pass current when the gate-source voltage is below the threshold voltage V. TH3 The voltage divider voltage VA is limited to equal to VA, and it functions as a voltage limiting circuit for the voltage divider voltage VA. The limit value of the voltage divider voltage VA at this time is expressed by equation 4 VA REF This is the result. Furthermore, since the potential difference between the input voltage VS and the source voltage of transistor M3 becomes greater than the voltage drop across resistor R1, the drain-source voltage of transistor M3 increases, and the current IS flowing through the input terminal T1 is expressed by equation 7.

[0048]

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[0049] [Mathematical formula]

[0050] Here, V D61 is the clamp voltage of the voltage clamp element 61.

[0051] When the input voltage VS further rises, exceeds the region D2 of Formula 6, and reaches the region D3 of Formula 8, the voltage clamp element 61 is turned on. While the transistor M4 is in the ON state, the current IS flowing through the input terminal T1 is the current generated by the constant current source 92 added to the current of Formula 7, as expressed by Formula 9 below, the current I 92 is added.

[0052] [Mathematical formula]

[0053] [Mathematical formula]

[0054] Here, V TH4 is the threshold voltage of the transistor M4, and I 92 is the current generated by the constant current source 92.

[0055] From Formula 7 and Formula 9, in the regions D2 and D3 of Formula 6 and Formula 8, even if the input voltage VS of the voltage detector 1 rises far beyond the voltage VS1, the divided voltage VA output from the resistive voltage divider unit 2 is limited by the operation of the transistor M3. Therefore, the current IS flowing through the input terminal T1 is not increased and is limited to a constant current.

[0056] When the voltage clamp element 61 is turned on, the gate of the transistor M4 is at VS-V D61It rises to this point. Therefore, when the input voltage VS rises further and reaches region D4 in equation 10, the gate voltage of transistor M4 rises and the gate-source voltage reaches the threshold voltage V TH4 Because it falls below a certain level, it enters the OFF state. The current IS flowing through input terminal T1 is expressed by equation 11.

[0057]

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[0058]

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[0059] From Equation 11, in the region of the input voltage VS given by Equation 10, even if the input voltage VS increases, the current IS flowing through the input terminal T1 does not increase, and the current I generated by the constant current source 92 does not increase. 92 It is suppressed.

[0060] In other words, even if the voltage VS input to input terminal T1 rises significantly above voltage VS1, the current IS flowing through the resistive voltage divider 2 and the voltage divider ratio control unit 6 is limited to a constant current when the input voltage VS is in regions D2 and D3, and suppressed to a minute current when the input voltage VS is in region D4.

[0061] In other words, in this first embodiment, even if the input voltage VS rises significantly above the voltage VS1, the voltage detector 1 suppresses the current IS flowing through the input terminal T1, thus also suppressing an increase in current consumption.

[0062] Therefore, it has the effect of reducing current consumption.

[0063] (Second Embodiment) Next, the voltage detector 1B of the second embodiment will be described with reference to Figure 3. In Figure 3, components identical to those in the circuit shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0064] As shown in the figure, the voltage detector 1B, similar to the first embodiment, includes a resistive voltage divider 2B, a differential input 3, an output 4, an output buffer 5, and a voltage divider ratio control unit 6B.

[0065] The difference between the first and second embodiments lies in the configuration of the resistor voltage divider 2B and the voltage division ratio control unit 6B. In the first embodiment, the voltage division ratio control unit 6 was composed of a voltage clamp element 61, while in the second embodiment, the voltage division ratio control unit 6B is composed of a voltage clamp element 61B and a transistor M5 (= fifth transistor). Furthermore, the resistor R1 that was composed in the first embodiment is divided into a divider resistor R11 (= first divider resistor) and a divider resistor R12 (= second divider resistor) in the second embodiment.

[0066] Transistor M5 is composed of an N-channel field-effect transistor. The drain of transistor M5 is connected to input terminal T1, and the gate is connected to the connection point between divider resistors R11 and R12.

[0067] The voltage clamp element 61B is connected between the source of transistor M5 and the gate of transistor M4.

[0068] Next, the current IS flowing through the input terminal T1 (resistive voltage divider unit 2B and voltage divider ratio control unit 6B) of the voltage detector 1B with the above configuration will be described below with reference to the current characteristics shown in Figure 4. The voltage detector 1B in this configuration is basically the same as in the first embodiment, except for the points described later.

[0069] The difference between the operation of the first embodiment and the second embodiment is that, in the on / off switching operation of transistor M4, the first embodiment did not have hysteresis characteristics, but the second embodiment does.

[0070] Until the input voltage VS reaches the upper limit of region D1 in equation 12, in the description of the first embodiment, “resistor R1” is replaced with “divider resistor (R11 + R12)” and “R1” is replaced with “R 11+R 12 "Voltage clamp element 61" is changed to "Voltage clamp element 61B", "V D61 " to "V D61B Since it can be explained by replacing it with "[this]", a detailed explanation will be omitted.

[0071] When the input voltage VS rises, transistor M4 is in the ON state. Therefore, the gate potential of transistor M5 is the input voltage VS minus the voltage drop across the divider resistor R11. When the input voltage VS reaches the voltage VS21 in equation 12, the gate voltage of transistor M4 rises, and the gate-source voltage reaches the threshold voltage V TH4 The voltage drops below this level, turning it off. Therefore, the voltage drop across the divider resistor R11 becomes zero.

[0072]

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[0073] Here, V D61B V is the clamping voltage of the voltage clamping element 61B. TH5 This is the threshold voltage of transistor M5.

[0074] After transistor M4 is turned off, if the input voltage VS decreases, the gate potential of transistor M5 becomes equal to the input voltage VS. Therefore, when the input voltage VS reaches the voltage VS22 in equation 13, transistor M4's gate voltage decreases and the gate-source voltage reaches the threshold voltage V TH4 It exceeds the limit and turns on.

[0075]

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[0076] In other words, the on / off switching operation of transistor M4 results in operation with hysteresis characteristics. Hysteresis voltage V HYS This is represented by Equation 14, which is the voltage difference between the input voltage VS21 represented by Equation 12 and the input voltage VS22 represented by Equation 13.

[0077]

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[0078] When the input voltage VS rises, the input voltage VS is in region D21 of Equation 15, and when the input voltage VS falls, the input voltage VS is in region D22 of Equation 16, the voltage clamp element 61B is in the off state and transistor M4 is in the on state. Transistor M3 is in the on state when the gate-source voltage is the threshold voltage V TH3 When the gate-source voltage falls below the threshold voltage V, current can no longer flow, so the gate-source voltage is below the threshold voltage V. TH3 It is limited to a voltage equal to and functions as a voltage limiting circuit for the divided voltage VA. The limit value of the divided voltage VA at this time is expressed by equation 4 VA REF This is the result. Furthermore, the potential difference between the input voltage VS and the source voltage of transistor M3 becomes greater than the voltage drop due to the sum of the resistance values ​​of divider resistors R11 and R12, so the drain-source voltage of transistor M3 increases, and the current IS flowing through the input terminal T1 is expressed by equation 17.

[0079]

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[0080]

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[0081]

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[0082] When the input voltage VS rises, the input voltage VS is in region D31 of Equation 18, and when the input voltage VS falls, the input voltage VS is in region D32 of Equation 19, the voltage clamp element 61B is ON, the transistor M4 is ON, and the current IS flowing through the input terminal T1 is expressed in Equation 20 as the current I generated by the constant current source 92 relative to the current in Equation 17. 92It will be added.

[0083]

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[0084]

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[0085]

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[0086] From equations 17 and 20, in regions D21, D22, D31, and D32, even if the input voltage VS of the voltage detector 1B rises significantly above the voltage VS1, the divided voltage VA output from the resistive voltage divider 2B is limited by the action of transistor M3, so the current IS flowing through the input terminal T1 does not increase and is limited to a constant current.

[0087] When the input voltage VS rises, the input voltage VS is in region D41 of Equation 21, and when the input voltage VS falls, the input voltage VS is in region D42 of Equation 22, the voltage clamp element 61B and transistor M5 are turned on. Transistor M4 turns on when the gate voltage rises and the gate-source voltage reaches the threshold voltage V TH4 When the value falls below a certain level, it turns off. The current IS flowing through input terminal T1 is expressed by equation 23.

[0088]

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[0089]

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[0090]

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[0091] From Equation 24, in regions D41 and D42, even if the input voltage VS increases, the current IS flowing through the input terminal T1 does not increase, and the current I generated by the constant current source 92 does not increase. 92 It is suppressed.

[0092] In other words, even if the voltage input to input terminal T1 rises significantly above the voltage VS1, the current IS flowing through the resistive voltage divider 2B and the voltage divider ratio control unit 6B is limited to a constant current when the input voltage VS is in regions D21, D22, D31, and D32, and suppressed to a minute current when the input voltage VS is in regions D41 and D42.

[0093] In other words, in this second embodiment, even if the input voltage VS rises significantly above the voltage VS1, the voltage detector 1B suppresses the current IS flowing through the input terminal T1, thus also suppressing an increase in current consumption.

[0094] Therefore, the second embodiment, like the first embodiment, also achieves the effect of reducing current consumption.

[0095] (Third embodiment) Next, the voltage detector 1C of the third embodiment will be described with reference to Figure 5. In Figure 5, components identical to those in the circuit shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0096] As shown in the figure, the voltage detector 1C, similar to the first embodiment, includes a resistive voltage divider 2, a differential input 3, an output 4, an output buffer 5, and a voltage divider ratio control unit 6C.

[0097] The difference between the first embodiment and the third embodiment is that the first embodiment includes a transistor M6 (= sixth transistor) in the voltage divider ratio control unit 6C.

[0098] Transistor M6 is composed of a P-channel field-effect transistor. The drain of transistor M6 is connected to the gate of transistor M4, and the gate is connected to the voltage divider voltage VA. A voltage clamp element 61C is connected between the input terminal T1 and the source of transistor M6.

[0099] Transistor M6 functions as a common-base circuit, improving the on / off switching speed of transistor M4.

[0100] In other words, in this third embodiment, even if the input voltage VS rises significantly above the voltage VS1, the voltage detector 1C can suppress the increase in current consumption because the current IS flowing through the input terminal T1 is suppressed.

[0101] Therefore, the third embodiment, like the first embodiment, also achieves the effect of reducing current consumption.

[0102] Furthermore, by connecting transistor M6, the on / off switching speed of transistor M4 is improved, which shortens the transition speed of the current IS flowing through the input terminal T1 between region D3 in Equation 6 and region D4 in Equation 8.

[0103] Similarly, in the second embodiment, transistor M6 may also be connected.

[0104] (Other embodiments) The present invention is not limited to the embodiments described above, and can be modified, improved, etc., as appropriate. Furthermore, the material, shape, dimensions, number, placement, etc., of each component in the embodiments described above are arbitrary and not limited, as long as they can achieve the present invention.

[0105] For example, in the first to third embodiments described above, the transistors were composed of field-effect transistors, but the invention is not limited to this. At least one of the transistors may be replaced with bipolar transistors. In this case, "P channel" can be read as "PNP type," "N channel" as "NPN type," "gate" as "base," "source" as "emitter," and "drain" as "collector" in the explanation.

[0106] In the first to third embodiments described above, the gate of transistor M3 was connected to the sources of transistors M1 and M2, but this is not the only option. Transistor M3 may be configured as a depletion-type field-effect transistor, and its gate may be connected to the reference voltage VREF. In this case, VA REF This is expressed by Equation 24.

[0107]

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[0108] Here, V TH3D This is the threshold voltage of the depletion-type field-effect transistor M3.

[0109] In the first to third embodiments described above, the circuit currents of the differential input section 3 and output section 4 are not controlled in accordance with the on / off switching operation of transistor M4, but the invention is not limited to this. The current consumption may be further reduced by configuring the circuit to interrupt the circuit currents of the differential input section 3 and output section 4 when transistor M4 is off, while maintaining a high potential for the output signal VOUT.

[0110] In the first to third embodiments described above, the output section 4 was configured with transistors M11 to M13 and a constant current source 91, but it is not limited to this configuration. Other embodiments are possible as long as the circuit generates a voltage corresponding to the current difference of the differential current generated by transistors M1 and M2.

[0111] Furthermore, in the first to third embodiments described above, the voltage detectors 1, 1B, and 1C had voltage clamp elements 61, 61B, and 61C, a constant current source 92, and a transistor M4, but are not limited to these. The voltage detectors 1, 1B, and 1C only need to have a transistor M3, and the voltage clamp elements 61, 61B, and 61C, the constant current source 92, and the transistor M4 are not required. [Explanation of Symbols]

[0112] 1,1B,1C Voltage Detector 2,2B Resistive voltage divider section 3. Differential Input Section 4 Output section 6, 6B, 6C Pressure Partition Ratio Control Unit 61, 61B, 61C Voltage Clamping Element 91 Current source VS Input Voltage M1 Transistor (First Transistor) M2 transistor (second transistor) M3 transistor (third transistor) M4 transistor (switch element, fourth transistor) M5 transistor (the fifth transistor) M6 transistor (6th transistor) R1 Resistor (First resistor) R2 Resistor (Second resistor) R11 Divider resistor (first divider resistor) R12 Voltage divider resistor (second divider resistor) T1 Input Terminal

Claims

1. A resistor voltage divider having a first resistor and a second resistor that divide the input voltage, A differential input unit having a first transistor to which a divided voltage obtained by dividing the input voltage is supplied to the gate or base, and a second transistor to which a reference voltage is supplied to the gate or base, which generates a differential current with a current ratio corresponding to the difference between each gate voltage or each base voltage, A voltage detector comprising an output unit that generates a voltage corresponding to the current difference of the differential current, The resistor voltage divider is provided between the first resistor and the second resistor, and further comprises a third transistor whose source or emitter is connected to the gate or base of the first transistor, and whose gate or base is also connected to the source or emitter of the first transistor. Voltage detector.

2. In the voltage detector according to claim 1, The resistor voltage divider further includes a switch element connected in series with the first resistor and the second resistor, which interrupts the current flowing through the first resistor and the second resistor. Voltage detector.

3. In the voltage detector according to claim 2, The aforementioned switch element is The source-drain or emitter-collector connection is made up of a fourth transistor connected between the gate or base of the first transistor and one end of the second resistor. Voltage detector.

4. In the voltage detector according to claim 3, The voltage divider ratio control unit further comprises a voltage clamping element connected between an input terminal to which the input voltage is supplied and the gate or base of the fourth transistor, The resistor voltage divider further comprises a current source connected between the gate or base of the fourth transistor and the other end of the second resistor. Voltage detector.

5. In the voltage detector according to claim 4, The first resistor is composed of a first divider resistor and a second divider resistor connected in series. The voltage divider ratio control unit has a fifth transistor whose source-drain or emitter-collector is connected between the input terminal and the voltage clamp element, and whose gate or base is connected to the connection point between the first divider resistor and the second divider resistor. Voltage detector.

6. In the voltage detector according to claim 4, The voltage divider ratio control unit further comprises a sixth transistor whose source-drain or emitter-collector is connected between the voltage clamping element and the current source, and whose gate or base is connected to the gate or base of the first transistor. Voltage detector.

7. A resistor voltage divider having a first resistor and a second resistor that divide the input voltage, A differential input unit having a first transistor to which a divided voltage obtained by dividing the input voltage is supplied to the gate or base, and a second transistor to which a reference voltage is supplied to the gate or base, which generates a differential current with a current ratio corresponding to the difference between each gate voltage or each base voltage, A voltage detector comprising an output unit that generates a voltage corresponding to the current difference of the differential current, The resistor voltage divider is provided between the first resistor and the second resistor, and further comprises a third transistor which is composed of a depletion-type electrolytic effect transistor whose source is connected to the gate or base of the first transistor and to which the reference voltage is supplied to the gate. Voltage detector.

8. In the voltage detector according to claim 2, When the switch element is off, the circuit currents of the differential input and output sections are interrupted. Voltage detector.

9. In the voltage detector according to any one of claims 1 to 8, At least one of the aforementioned transistors is composed of bipolar transistors. Voltage detector.

10. In the voltage detector according to any one of claims 1 to 8, At least one of the aforementioned transistors is composed of an electrolytic effect transistor. Voltage detector.

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