Voltage detector and voltage detection device

Abstract

The present invention provides a voltage detector and voltage detection device that reduce current consumption while improving the accuracy of detected voltage and hysteresis voltage. [Solution] The resistor voltage divider unit 3 has a plurality of resistors R11, R12, R13 connected in series to divide the input voltage VS, and outputs a divided voltage VA obtained by dividing the input voltage VS. The voltage comparison unit 4 compares the divided voltage VA with a reference voltage VREF and outputs an output signal VOUT. The voltage generation unit 5 has a current source 51 that supplies current to an externally connected hysteresis adjustment resistor R1, and a switch element 52 that is on / off controlled by the output signal OUT and supplies / cuts the current from the current source 51 to the resistor R1. The voltage-to-current conversion unit 6 converts the voltage across the resistor R1 into current. HYS However, it was designed to be drawn out from some of the resistors R11, R12, and R13.

Description

[Technical Field]

[0001] The present invention relates to a voltage detector and a voltage detection device. [Background technology]

[0002] With the rapid advancement of the information and communication society, reducing power consumption, increasing accuracy, and ensuring stable operation of electronic devices have become major challenges. To ensure stable operation of the circuits and systems that make up electronic devices, a voltage detector is needed that can detect voltage values ​​with high accuracy and with minimal fluctuations in the detected voltage in all environments. This invention aims to reduce current consumption, improve the accuracy of the detected voltage and hysteresis voltage, and enable optimization of the hysteresis voltage, thereby suppressing malfunctions caused by noise and contributing to the stable operation of the system. In particular, this invention relates to a voltage detector equipped with a function that allows adjustment of the hysteresis voltage by a resistor connected to an external connection terminal.

[0003] In semiconductor integrated circuits, increasing the number of external terminals is undesirable because it leads to an increase in external size and cost. Conventionally, a voltage detector that allows external adjustment of the hysteresis voltage setting by adding only one terminal is known, as shown in Figure 5 (see, for example, Patent Documents 1 and 2). The conventional voltage detector 100 shown in Figure 5 is mainly composed of a resistive voltage divider 103 that outputs a divided voltage based on the input voltage, and a voltage comparator 41 that compares the divided voltage VA with a reference voltage VREF and outputs an output signal.

[0004] The resistive voltage divider 103 has resistors R11 and R12 connected in series between the input terminal T11 to which the input voltage VS is input and the external connection terminal T12 to which resistor R1 is connected. The divided voltage VA (voltage generated at junction node A) is output from the connection point (junction node A) between resistors R11 and R12. The divided voltage VA changes based on the voltage VS input to the input terminal T11.

[0005] The voltage comparator 41 has a reference voltage source 42 that generates a reference voltage VREF connected to its inverting input, a junction node A connected to its non-inverting input, and an output terminal T3 connected to its output, and outputs an output signal VOUT.

[0006] Furthermore, in the voltage detector 100, when noise is superimposed on the input voltage VS and the divided voltage VA approaches the vicinity of the reference voltage VREF, the relative magnitudes of the divided voltage VA and the reference voltage VREF are quickly reversed due to the noise. As a result, a chattering phenomenon occurs in which the output signal VOUT repeatedly fluctuates between high and low potentials.

[0007] To avoid false detections due to chattering, a voltage detector 100 with hysteresis characteristics is commonly used. Furthermore, since the amount of noise varies depending on the system environment, it is necessary to adjust the hysteresis voltage to an optimal value to suppress malfunctions due to chattering.

[0008] The resistor R1, which sets the hysteresis voltage, is connected between the external connection terminal T12 and the negative power supply terminal T21, to which the negative power supply voltage VSS is supplied. A switch element 52 connected in parallel with resistor R1 is controlled on and off according to the output signal VOUT, thereby generating the hysteresis voltage.

[0009] Next, the operation of the conventional voltage detector 100 will be described below.

[0010] When the input voltage VS is high and the divided voltage VA is higher than the reference voltage VREF, the voltage comparator 41 outputs a High potential, and the output signal VOUT is also High. This state is called the deactivated state of the voltage detector. When the input voltage VS is low and the divided voltage VA is lower than the reference voltage VREF, the voltage comparator 41 outputs a Low potential, and the output signal VOUT is also Low. This state is called the detected state of the voltage detector.

[0011] In the deactivated state, the output of the voltage comparator 41 is at a high potential, the switch element 52 is open, and the detected voltage V D1is represented by Equation 1. In the detection state, the output of the voltage comparator 41 is at a Low potential, the switch element 52 is in a short-circuited state, and the release voltage V D2 is represented by Equation 2.

[0012] [Formula]

[0013] [Formula]

[0014] Here, R 11 is the resistance value of the resistor R11, R 12 is the resistance value of the resistor R12, and R1 is the resistance value of the resistor R1.

[0015] That is, by performing on-off control of the switch element 52 in accordance with the output signal of the voltage comparator 41, the voltage division ratio of the resistive voltage dividing unit 103 is switched, and the hysteresis voltage V HYS is generated. The hysteresis voltage V HYS is represented by Equation 3, which is the voltage difference between the detection voltage V D1 and the release voltage V D2 .

[0016] [Formula]

[0017] From Equation 3, the hysteresis voltage V HYS is set by the resistance value ratio of the resistors R11, R12, and R1. The resistors R11 and R12 are formed inside the semiconductor integrated circuit, and the resistor R1 is a discrete resistor connected to the outside of the semiconductor integrated circuit. Compared with the resistor R1, the resistors R11 and R12 have larger manufacturing variations and larger variation amounts of resistance values due to temperature changes.

[0018] Conventional voltage detectors 100 suffer from large variations in detected voltage and hysteresis voltage due to the difference in characteristics between resistors R11 and R12 formed inside the semiconductor integrated circuit and resistor R1 connected externally.

[0019] Furthermore, as an example of a conventional voltage detector that allows external setting of the hysteresis voltage with the addition of a single terminal and reduces variations in the detected voltage and hysteresis voltage, the voltage detector 200 shown in Figure 6 is known.

[0020] Conventional voltage detectors 200 have an external configuration in which resistors R101, R102, and R1 are connected to set the detection voltage and hysteresis voltage. Since resistors R101, R102, and R1 have the same characteristics, the accuracy of the detection voltage and hysteresis voltage can be improved. However, since resistors R101, R102, and R1 are generally discrete resistors with readily available resistance values ​​of several tens of ohms to several hundred kΩ, the current flowing through the resistor voltage divider 202 becomes large, resulting in high current consumption.

[0021] In the conventional voltage detector 100 described above, the difference in characteristics between resistors R11, R12 and resistor R1 leads to large variations in the detected voltage and hysteresis voltage. In the conventional voltage detector 200 described above, discrete resistors are connected to resistors R101, R102, and R1, resulting in a large current flowing through the resistor voltage divider 202 and thus high current consumption. In other words, conventional voltage detectors have the challenge of not being able to achieve both high accuracy in detected voltage and hysteresis voltage and low current consumption. [Prior art documents] [Patent Documents]

[0022] [Patent Document 1] Patent No. 7131965 [Patent Document 2] Japanese Patent Publication No. 2004-198335 [Overview of the Initiative] [Problems that the invention aims to solve]

[0023] The present invention has been made in view of the above circumstances, and its purpose is to provide a voltage detector and voltage detection device that reduce current consumption and improve the accuracy of detected voltage and hysteresis voltage. [Means for solving the problem]

[0024] To achieve the aforementioned objectives, the voltage detector and voltage detection device according to the present invention are characterized by the following [1] to [6]. [1] A voltage detector formed as a semiconductor integrated circuit on a semiconductor substrate, which monitors the input voltage input to the input terminal of the semiconductor integrated circuit, A resistor voltage divider unit having a plurality of first internal resistors connected in series with each other to divide the input voltage, and outputting divided voltages obtained by dividing the input voltage, A voltage comparison unit compares the divided voltage with a reference voltage and outputs an output signal. A voltage generating unit having a current source that supplies current to a first external resistor for hysteresis adjustment externally connected to the semiconductor integrated circuit, and a switch element that is on / off controlled by the output signal and supplies / cuts current from the current source to the first external resistor, The system comprises a voltage-to-current conversion unit that converts the voltage of the first external resistor into a current, The current converted by the voltage-current conversion unit is provided to be drawn from some of the multiple first internal resistors. It is a voltage detector. [2] In the voltage detector described in [1], The aforementioned voltage-current conversion unit is A second internal resistor, one end of which is connected to one end of the first external resistor, A differential amplifier in which the other end of the first external resistor is connected to the first input and the other end of the second internal resistor is connected to the second input, A transistor whose source or emitter is connected to the connection point between the second internal resistor and the second input, and whose gate or base is connected to the output of the differential amplifier, The system includes a current folding circuit that folds back the current flowing through the transistor, thereby drawing the current flowing through the transistor from a portion of the first internal resistor. It is a voltage detector. [3] In the voltage detector described in [2], The intermittent control unit further includes an oscillator that intermittently turns off the switching element, and a sample-and-hold circuit connected between the other end of the first external resistor and the first input of the differential amplifier. It is a voltage detector. [4] In the voltage detector described in [2] or [3], The aforementioned transistor is composed of bipolar transistors. It is a voltage detector. [5] In the voltage detector described in [2] or [3], The aforementioned transistor is composed of electrolytic effect transistors. It is a voltage detector. [6] A voltage detector formed as a semiconductor integrated circuit on a semiconductor substrate, which monitors the input voltage input to the input terminal of the semiconductor integrated circuit, The semiconductor integrated circuit is further equipped with a first external resistor for hysteresis adjustment, which is externally connected to the semiconductor integrated circuit. In a voltage detection device, The voltage detector is A resistor voltage divider unit having a plurality of first internal resistors connected in series with each other to divide the input voltage, and outputting divided voltages obtained by dividing the input voltage, A voltage comparison unit compares the divided voltage with a reference voltage and outputs an output signal. A voltage generating unit having a current source that supplies current to the first external resistor, and a switch element that is on / off controlled by the output signal and supplies / interrupts current from the current source to the first external resistor, The system comprises a voltage-to-current conversion unit that converts the voltage of the first external resistor into a current, The current converted by the voltage-current conversion unit is provided to be drawn from some of the multiple first internal resistors. It must be a voltage detection device. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a voltage detector and a voltage detection device that reduce current consumption and improve the accuracy of detected voltage and hysteresis voltage.

[0026] 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]

[0027] [Figure 1] Figure 1 is a circuit diagram showing a voltage detector in the first embodiment. [Figure 2] Figure 2 is a circuit diagram showing a voltage detector in the second embodiment. [Figure 3] Figure 3 is a circuit diagram showing a voltage detector in the third embodiment. [Figure 4] Figure 4 shows the voltage divider characteristics and the voltage characteristics across resistor R1 with respect to the input voltage VS of the voltage detector in the first to third embodiments. [Figure 5] Figure 5 is a circuit diagram showing an example of a conventional voltage detector. [Figure 6] Figure 6 is a circuit diagram showing an example of a conventional voltage detector with an externally connected resistive voltage divider. [Modes for carrying out the invention]

[0028] Specific embodiments of the present invention will be described below with reference to the figures.

[0029] (First Embodiment) First, the voltage detection device 1 of the first embodiment will be described with reference to Figure 1. As shown in the figure, the voltage detection device 1 comprises a voltage detector 2 and a resistor R1 (= first external resistor) externally connected to the voltage detector 2. The voltage detector 2 is formed as a semiconductor integrated circuit on a semiconductor substrate and monitors the input voltage VS input to the input terminal T11 of the semiconductor integrated circuit. The voltage detector 2 comprises a resistance voltage divider unit 3, a voltage comparison unit 4, a voltage generation unit 5, and a voltage-to-current conversion unit 6.

[0030] The resistive voltage divider 3 consists of resistors R11, R12, and R13 (= first internal resistors) connected in series between the input terminal T11, to which the input voltage VS is input, and the negative power supply terminal T21. The negative power supply voltage VSS is supplied to the negative power supply terminal T21.

[0031] A divided voltage VA (voltage generated at junction node A) is output from the connection point (junction node A) between resistors R12 and R13, based on the input voltage VS. The divided voltage VA is the voltage obtained by dividing the input voltage VS according to the resistance ratio of resistors (R11 + R12) and resistor R13.

[0032] The voltage comparison unit 4 consists of a voltage comparator 41 and a reference voltage source 42. The voltage comparison unit 4 compares the reference voltage VREF generated by the reference voltage source 42 with the divided voltage VA generated by the resistive voltage divider unit 3 and outputs the comparison result.

[0033] The voltage comparator 41 has an inverting input connected to a reference voltage VREF, a non-inverting input connected to a voltage divider VA, and an output connected to output terminal T3, outputting an output signal VOUT.

[0034] The voltage generation unit 5 includes a current source 51 that supplies current to resistor R1, and a switch element 52 that is controlled on / off by the output signal VOUT to supply and interrupt current from the current source 51 to resistor R1. The current source 51, switch element 52, and resistor R1 are connected in series between the negative power supply terminal T21 and the positive power supply terminal T22. The positive power supply voltage VDD is supplied to the positive power supply terminal T22. Resistor R1 is connected between the positive power supply terminal T22 and the external connection terminal T12. The series-connected current source 51 and switch element 52 are connected between the non-inverting input (=first input) of the differential amplifier 61 (described later) and the negative power supply terminal T21. The switch element 52 is controlled on / off according to the output signal VOUT, and by supplying current generated by the constant current source 51 to resistor R1, it generates a voltage across resistor R1 based on the current and resistance value.

[0035] The voltage-to-current conversion unit 6 converts the voltage generated across resistor R1 into a current and extracts the converted current from a portion of resistors R11-R13 (in this embodiment, resistors R12 and R13). The voltage-to-current conversion unit 6 consists of a differential amplifier 61, resistor R2 (= second internal resistance), transistor M1, and current folding circuit 62. Transistor M1 is a P-channel field-effect transistor. The differential amplifier 61 has an inverting input connected to the connection point between resistor R2 and the source of transistor M1, a non-inverting input connected to the external connection terminal T12, and an output connected to the gate of transistor M1.

[0036] The differential amplifier 61 forms a negative feedback loop when combined with transistor M1. Therefore, the voltage across resistor R1 is controlled to be equal to the voltage across resistor R2, and a current based on the voltage across resistor R1 and the resistance of resistor R2 is output from the drain of transistor M1. The drain of transistor M1 is connected to the current loopback circuit 62.

[0037] The current folding circuit 62 folds back the current flowing to the drain of transistor M1, drawing the current flowing from resistors R12 and R13 to the drain of transistor M1. The current folding circuit 62 is composed of transistors M2 and M3. Transistors M2 and M3 are composed of N-channel field-effect transistors. The gate and drain of transistor M2 are connected to the drain of transistor M1, and the source is connected to the negative power supply terminal T21. The drain of transistor M3 is connected to the connection point of resistors R11 and R12, the source is connected to the negative power supply terminal T21, and the gate is connected to the gate and drain of transistor M2. In other words, transistor M3 is current-mirror connected to transistor M2, copying and folding back the current flowing to transistor M2.

[0038] Next, the operation of the voltage detector 2 with the above configuration will be explained below, referring to the divided voltage characteristics with respect to the input voltage VS and the voltage characteristics across resistor R1 shown in Figure 4. First, 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, that is, the output signal VOUT is approximately the positive power supply voltage VDD.

[0039] In the release state, when the divided voltage VA is higher than the reference voltage VREF, the output of the voltage comparator 41 is at a high potential, the switching element 52 is off, and the current I generated by the constant current source 51 is 51 The signal is interrupted. The voltage across resistor R1 becomes zero, and the hysteresis current I HYS This becomes zero. In the release state, where the divided voltage VA is higher than the reference voltage VREF, the divided voltage VA is expressed by Equation 4.

[0040]

number

[0041] Furthermore, when the divided voltage VA decreases and the divided voltage VA falls below the reference voltage VREF, the output of the voltage comparator 41 becomes low, and it transitions from the release state to the detection state. Detected voltage V D1This is expressed by equation 5.

[0042]

number

[0043] Here, R 11 The resistance value of resistor R11 is R 12 The resistance value of resistor R12 is R 13 This is the resistance value of resistor R13.

[0044] From Equation 5, the detected voltage V D1 This depends on the resistance ratio of resistors R11, R12, and R13 formed inside the semiconductor integrated circuit. As explained in the background technology, resistors R11, R12, and R13 have large manufacturing variations and large fluctuations in resistance due to temperature changes, but the same manufacturing variations occur and the fluctuations in resistance due to temperature changes are the same. Therefore, the resistance ratio of resistors R11, R12, and R13 cancels out the effects of manufacturing variations and temperature changes, making it less susceptible to the effects of manufacturing variations and temperature changes. Therefore, the detected voltage V D1 This allows for increased accuracy.

[0045] Next, we will explain the operation of the detection state where the divided voltage VA is lower than the reference voltage VREF, and the output low potential of the output terminal T3, i.e., the output signal VOUT is approximately the negative power supply voltage VSS.

[0046] Due to the operation of the voltage-to-current conversion unit 6, the voltage VR1 across resistor R1 is applied across resistor R2, resulting in a hysteresis current I HYS This is generated. If the aspect ratio S(W / L) ratios of the currently mirrored transistors M2 and M3 are equal, the hysteresis current I HYS This is expressed by equation 6.

[0047]

number

[0048] Here, VR1 is the voltage across resistor R1, R1 is the resistance of resistor R1, R2 is the resistance of resistor R2, I 51 This is the current generated by the constant current source 51.

[0049] When the divided voltage VA is detected to be lower than the reference voltage VREF, the output of the voltage comparator 41 is at a low potential, the switching element 52 is short-circuited, and the current I generated by the constant current source 51 51 A current flows through resistor R1. A voltage VR1 is generated across resistor R1, and a hysteresis current I is generated via the voltage-to-current conversion unit 6. HYS When the divided voltage VA is detected to be lower than the reference voltage VREF, the divided voltage VA is expressed by Equation 7.

[0050]

number

[0051] Furthermore, when the divided voltage VA rises and exceeds the reference voltage VREF, the output of the voltage comparator 41 becomes high, and the system transitions from the detection state to the release state. Release voltage V D2 This is expressed by equation 8.

[0052]

number

[0053] From equation 6, the release voltage V D2 This depends on the resistance ratio of resistors R11, R12, and R13 formed inside the semiconductor integrated circuit, the resistance ratio of resistors R11 and R2 formed inside the semiconductor integrated circuit, and the resistance of resistor R1 connected to the outside of the semiconductor integrated circuit. The resistance ratio of resistors R11, R12, and R12 and the resistance ratio of resistors R11 and R2 are formed inside the semiconductor integrated circuit, so they are less affected by manufacturing variations and temperature changes. Also, resistor R1 connected to the outside of the semiconductor integrated circuit has small manufacturing variations and the amount of resistance change due to temperature changes is small. Therefore, the release voltage V D2 This allows for increased accuracy.

[0054] Next, the operation exhibiting hysteresis characteristics will be explained below.

[0055] The voltage detector 2 controls the on / off state of the switch element 52 in accordance with the output signal VOUT of the voltage comparator 41, thereby drawing out the hysteresis current I from the connection point between resistors R11 and R12. HYS The voltage drop across resistor R11 is controlled by the hysteresis voltage V. HYS This generates a hysteresis voltage V. HYS The detected voltage V D1 and release voltage V D2 This represents the voltage difference, which is expressed in Equation 9.

[0056]

number

[0057] From Equation 9, the hysteresis voltage V HYS This depends on the resistance ratio of resistors R11 and R2 formed inside the semiconductor integrated circuit and the resistance of resistor R1 connected outside the semiconductor integrated circuit. The resistance ratio of resistors R11 and R2 is less affected by manufacturing variations and temperature changes, so the hysteresis voltage V HYS This allows for increased accuracy.

[0058] Furthermore, in the release state, when the system where the voltage is monitored by the voltage detector is in a steady state, the current I generated by the constant current source 51 51 Since the current is interrupted by the switch element 52, the current consumption can be reduced.

[0059] In other words, the voltage detector 2 in this first embodiment can achieve high accuracy because the resistance ratio of each resistor used to set the detection voltage and hysteresis voltage is less susceptible to manufacturing variations and temperature changes. 51 Since it does not flow during the steady state when the circuit is released, current consumption can be reduced.

[0060] Therefore, this method offers the advantage of reducing current consumption while simultaneously improving the accuracy of detection voltage and hysteresis voltage.

[0061] (Second Embodiment) Next, the voltage detection device 1B of the second embodiment will be described with reference to Figure 2. In Figure 2, components identical to those in the circuit shown in Figure 1 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0062] As shown in the figure, the voltage detection device 1B includes a voltage detector 2B and a resistor R1. The voltage detector 2B includes a resistive voltage divider 3, a voltage comparison unit 4, a voltage generation unit 5, a voltage-to-current conversion unit 6, and an intermittent control unit 7.

[0063] The difference between the first embodiment and the second embodiment is that the voltage detector 2 in the first embodiment is equipped with an intermittent control unit 7.

[0064] The intermittent control unit 7 consists of a sample-and-hold circuit 71 and an oscillator 72. By providing the intermittent control unit 7 between the voltage generation unit 5 and the non-inverting input of the differential amplifier 61, the current flowing through resistor R1 can be made to operate intermittently, thereby reducing the average current. During the period when the current flowing through resistor R1 is interrupted by the switch element 52, the voltage information across resistor R1 is transmitted to the non-inverting input of the differential amplifier 61, with the voltage held by the sample-and-hold circuit 71 being transmitted.

[0065] The current flowing through resistor R1 is the average current I obtained by multiplying the pulse signal generated by oscillator 72 by its duty cycle D. AVE It is reduced to and expressed in equation 10.

[0066]

number

[0067] In other words, the voltage detector 2B in this second embodiment can achieve high accuracy because the resistance ratio of each resistor used to set the detection voltage and hysteresis voltage is less susceptible to manufacturing variations and temperature changes. 51 In the deactivated state, the current is cut off, and in the detected state, it is averaged and reduced by the intermittent control unit 7, thus reducing the current consumption.

[0068] Therefore, the second embodiment, like the first embodiment, achieves the effect of reducing current consumption and improving the accuracy of detection voltage and hysteresis voltage.

[0069] (Third embodiment) Next, the voltage detection device 1C of the third 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.

[0070] As shown in Figure 3, the voltage detection device 1C includes a voltage detector 2C and a resistor R1, similar to the first embodiment. The voltage detector 2C includes a resistive voltage divider 3, a voltage comparison unit 4, a voltage generation unit 5C, and a voltage-to-current conversion unit 6C, similar to the first embodiment.

[0071] The differences between the first and third embodiments are that the conductivity types of transistors M1C to M3C, corresponding to transistors M1 to M3, are reversed, and the relationship between the negative power supply terminal T21 and the positive power supply terminal T22 is reversed. In the third embodiment, the negative power supply terminal T21 corresponds to the second power supply terminal, and the positive power supply terminal T22 corresponds to the first power supply terminal.

[0072] In the first embodiment, the current folding circuit 62 was composed of transistors M2 and M3, but in the third embodiment, the current folding circuit 62C is composed of transistors M4 and M5 in addition to transistors M2C and M3C.

[0073] Transistors M4 and M5 are composed of N-channel field-effect transistors. Transistor M4 has its gate and drain connected to the drain of transistor M3C, and its source connected to the negative power supply terminal T21. Transistor M5 has its drain connected to the connection point of resistors R11 and R12, its source connected to the negative power supply terminal T21, and its gate connected to the gate and drain of transistor M4. In other words, transistor M5 is current-mirror-connected to transistor M4, copying and folding back the current flowing through transistor M4.

[0074] Due to the operation of the voltage-to-current conversion unit 6C, the voltage VR1 across resistor R1 is applied across resistor R2C, resulting in a hysteresis current I HYS The following is generated. If the ratio of aspect ratios S(W / L) of transistors M2C and M3C connected via current mirroring is equal to the ratio of aspect ratios S(W / L) of transistors M4 and M5 connected via current mirroring, then a hysteresis current I HYS This is represented by equation 11.

[0075]

number

[0076] Here, R 2C The resistance value of resistor R2C is I. 51C This is the current generated by the constant current source 51C.

[0077] The voltage detector 2C controls the on / off state of the switch element 52C in accordance with the output signal of the voltage comparator 41, thereby drawing out a hysteresis current I from the connection point between resistors R11 and R12. HYS The voltage drop across resistor R11 is controlled by the hysteresis voltage V. HYS This generates a hysteresis voltage V. HYS This is expressed in Equation 12.

[0078]

number

[0079] From Equation 12, the hysteresis voltage V HYS This depends on the resistance ratio of resistors R11 and R2C formed inside the semiconductor integrated circuit and the resistance of resistor R1 connected outside the semiconductor integrated circuit. The resistance ratio of resistors R11 and R2C is less affected by manufacturing variations and temperature changes, so the hysteresis voltage V HYS This allows for increased accuracy.

[0080] Furthermore, in the release state, when the system where the voltage is monitored by the voltage detector is in a steady state, the current I generated by the constant current source 51C 51C Since the current is interrupted by the switch element 52C, the current consumption can be reduced.

[0081] In other words, the voltage detector 2C in this third embodiment can achieve high accuracy because the resistance ratio of each resistor used to set the detection voltage and hysteresis voltage is less susceptible to manufacturing variations and temperature changes. 51C Since it does not flow during the steady state when the circuit is released, current consumption can be reduced.

[0082] Therefore, the third embodiment, like the first embodiment, achieves the effect of reducing current consumption and improving the accuracy of detection voltage and hysteresis voltage.

[0083] Similarly, in the second embodiment, the conductivity type of the transistor may be reversed, and the relationship between the negative power supply terminal T21 and the positive power supply terminal T22 may be reversed.

[0084] (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.

[0085] 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.

[0086] In the first to third embodiments described above, a hysteresis current I is generated between resistor R11 and resistor R12. HYS The current being drawn out, that is, the current flowing through resistors R12 and R13, was being drawn out, but this is not the only way. It is sufficient to draw out the hysteresis current from some of the resistors, for example, by drawing out the current between resistors R12 and R13, that is, the current flowing through resistor R13. [Explanation of Symbols]

[0087] 1,1B,1C Voltage detection device 2,2B,2C Voltage Detector 3. Resistive voltage divider section 4. Voltage comparison section 5. Voltage generation unit 6,6C Voltage-Current Conversion Section 51 Current source 52 Switching elements 61 Differential Amplifier 62,62C current folding circuit 71 Sample-and-Hold Circuit 72 Oscillators M1, M1C transistors R1 Resistor (First external resistor) R2, R2C Resistors (Second internal resistors) R11, R12, R13 Resistors (First internal resistors) VS Input Voltage

Claims

1. A voltage detector formed as a semiconductor integrated circuit on a semiconductor substrate, which monitors the input voltage input to the input terminal of the semiconductor integrated circuit, A resistor voltage divider unit having a plurality of first internal resistors connected in series with each other to divide the input voltage, and outputting divided voltages obtained by dividing the input voltage, A voltage comparison unit compares the divided voltage with a reference voltage and outputs an output signal. A voltage generating unit having a current source that supplies current to a first external resistor for hysteresis adjustment externally connected to the semiconductor integrated circuit, and a switch element that is on / off controlled by the output signal and supplies / cuts current from the current source to the first external resistor, The system comprises a voltage-to-current conversion unit that converts the voltage of the first external resistor into a current, The current converted by the voltage-current conversion unit is drawn out from a portion of the plurality of first internal resistors. Voltage detector.

2. In the voltage detector according to claim 1, The aforementioned voltage-current conversion unit is A second internal resistor, one end of which is connected to one end of the first external resistor, A differential amplifier in which the other end of the first external resistor is connected to the first input and the other end of the second internal resistor is connected to the second input, A transistor whose source or emitter is connected to the connection point between the second internal resistor and the second input, and whose gate or base is connected to the output of the differential amplifier, The system includes a current folding circuit that folds back the current flowing through the transistor, thereby drawing the current flowing through the transistor from a portion of the first internal resistor. Voltage detector.

3. In the voltage detector according to claim 2, The intermittent control unit further includes an oscillator that intermittently turns off the switch element, and a sample-and-hold circuit connected between the other end of the first external resistor and the first input of the differential amplifier. Voltage detector.

4. In the voltage detector according to claim 2 or 3, The aforementioned transistor is composed of bipolar transistors. Voltage detector.

5. In the voltage detector according to claim 2 or 3, The aforementioned transistor is composed of electrolytic effect transistors. Voltage detector.

6. A voltage detector formed as a semiconductor integrated circuit on a semiconductor substrate, which monitors the input voltage input to the input terminal of the semiconductor integrated circuit, The semiconductor integrated circuit is further equipped with a first external resistor for hysteresis adjustment, which is externally connected to the semiconductor integrated circuit. In a voltage detection device, The voltage detector is A resistor voltage divider unit having a plurality of first internal resistors connected in series with each other to divide the input voltage, and outputting divided voltages obtained by dividing the input voltage, A voltage comparison unit compares the divided voltage with a reference voltage and outputs an output signal. A voltage generating unit having a current source that supplies current to the first external resistor, and a switch element that is on / off controlled by the output signal and supplies / interrupts current from the current source to the first external resistor, The system comprises a voltage-to-current conversion unit that converts the voltage of the first external resistor into a current, The current converted by the voltage-current conversion unit is drawn out from a portion of the plurality of first internal resistors. Voltage detection device.

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