Voltage generation circuit

Abstract

This invention provides a voltage generation circuit that can rapidly stabilize the output voltage while reducing noise, even when generating the output voltage using a capacitor. [Solution] The voltage generation circuit comprises a voltage input terminal to which an input voltage is input, a voltage output terminal to which an output voltage is output, a first resistor having a first terminal and a second terminal, the first terminal being electrically connected to the voltage input terminal and the second electrical terminal being electrically connected to the voltage output terminal, a second resistor having a third terminal and a fourth terminal, the third terminal being electrically connected to the second terminal, a first capacitor electrically connected to one of the first terminal and the second terminal, and a first circuit including a charging circuit electrically connected to one of the first terminal and the second terminal for charging the first capacitor.

Description

[Technical Field]

[0001] This disclosure relates to a voltage generation circuit. [Background technology]

[0002] Conventionally, voltage generation circuits that generate a predetermined voltage are known. As an example of a voltage generation circuit, the differential amplifier described in Patent Document 1 is known. This differential amplifier divides the power supply voltage Vcc using a series circuit of resistor 2 and resistor 3, and stabilizes the voltage across resistor 3 with capacitor 4. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. Hei 1-200708 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the differential amplifier described in Patent Document 1, when an output voltage is generated using a capacitor, it is difficult to reduce noise while stabilizing the output voltage at high speed, and there is room for improvement.

[0005] This disclosure provides a voltage generation circuit that can reduce noise and stabilize the output voltage at high speed, even when generating the output voltage using a capacitor. [Means for solving the problem]

[0006] One aspect of the present disclosure is a voltage generation circuit comprising: a voltage input terminal to which an input voltage is input; a voltage output terminal to which an output voltage is output; a first resistor having a first terminal and a second terminal, the first terminal of which is electrically connected to the voltage input terminal and the second electrical terminal of which is electrically connected to the voltage output terminal; a second resistor having a third terminal and a fourth terminal, the third terminal of which is electrically connected to the second terminal; a first capacitor electrically connected to one of the first terminal and the second terminal; and a first circuit including a charging circuit electrically connected to one of the first terminal and the second terminal for charging the first capacitor. [Effects of the Invention]

[0007] According to this disclosure, even when generating an output voltage using a capacitor, it is possible to reduce noise and stabilize the output voltage at high speed. [Brief explanation of the drawing]

[0008] [Figure 1] Diagram showing the configuration of the voltage generation circuit in the comparative example. [Figure 2A] This figure shows the change in the input voltage and the voltage at point A of the comparative example voltage generation circuit. [Figure 2B] This diagram shows the current flowing from resistor R20 to capacitor C20 in the voltage generation circuit of the comparative example. [Figure 2C] This diagram shows the relationship between gain and frequency in the comparative example voltage generation circuit. [Figure 3A] This figure shows a first example of the configuration of a voltage generation circuit according to an embodiment of the present disclosure. [Figure 3B] This figure shows a second example of the configuration of a voltage generation circuit. [Figure 4] A diagram showing the voltage at each point in a voltage generation circuit. [Figure 5A] This diagram shows the voltages at the voltage input terminal and voltage output terminal of the voltage generation circuit in the comparative example. [Figure 5B] This figure shows the amplitude spectra of the voltages at the voltage input and output terminals of the voltage generation circuit in the comparative example. [Figure 6A] This figure shows a comparison of the voltages at the voltage input terminal and voltage output terminal of the voltage generation circuit of the embodiment. [Figure 6B] Figure showing the voltage amplitude spectra of the voltage input terminal and voltage output terminal of the voltage generation circuit of the embodiment [Figure 7] Figure showing the configuration of the voltage generation circuit when using a FET for the transistor [Figure 8] Figure showing the case where the voltage generation circuit includes a bias power supply circuit and an additional circuit [Figure 9] Figure showing the change in the voltage at point A when the capacitor C20 of the voltage generation circuit of the comparative example is 220 μF and the capacitor C1 of the voltage generation circuit of the embodiment is 2200 μF [Figure 10] Figure comparing information regarding the resistor R3 [Figure 11] Figure showing the charging current characteristics from the resistor R3 to the capacitor C1 [Figure 12] Figure showing the charging waveform and equivalent rectangular waveform of the charging current of the capacitor C1 [Figure 13] Figure showing the charging waveform and equivalent rectangular waveform of the capacitor C1 until the charging current reaches 0.5Ip [Figure 14] Figure showing in a table the relationship between the output voltage / input voltage and the reduction factor [Figure 15A] Figure for explaining the dead zone voltage [Figure 15B] Figure for explaining the time Toffon at power supply reconnection [Figure 16] Figure showing the output voltage when a positive voltage is output by the positive power supply in the voltage generation circuit [Figure 17A] Figure showing the configuration of the voltage generation circuit when a negative voltage is output by the negative power supply in the voltage generation circuit [Figure 17B] Figure showing the output voltage of the voltage generation circuit when a negative voltage is output by the negative power supply in the voltage generation circuit [Figure 18A] Figure showing the configuration of the voltage generation circuit when the voltage generation circuit 1 as a dual power supply circuit outputs a positive voltage [Figure 18B] Figure showing the output voltage of the voltage generation circuit when the voltage generation circuit 1 as a dual power supply circuit outputs a positive voltage [Figure 19A]This diagram shows the configuration of a voltage generation circuit in another case where the voltage generation circuit 1, which uses both power supply voltages, outputs a positive voltage. [Figure 19B] This diagram shows the output voltage of the voltage generation circuit in another case where the voltage generation circuit 1, acting as a dual power supply circuit, outputs a positive voltage. [Figure 20A] This diagram shows the configuration of a voltage generation circuit when it outputs a negative voltage as a negative power supply circuit. [Figure 20B] This diagram shows the output voltage of a voltage generation circuit when it outputs a negative voltage as a negative power supply circuit. [Figure 21A] This diagram shows the configuration of the voltage generation circuit when the voltage generation circuit 1, acting as a dual power supply circuit, outputs a negative voltage. [Figure 21B] This diagram shows the output voltage of the voltage generation circuit when the voltage generation circuit 1, acting as a dual power supply circuit, outputs a negative voltage. [Figure 22A] This diagram shows the configuration of a voltage generation circuit to further improve safety in the event of a failure. [Figure 22B] This diagram shows the output voltage of a voltage generation circuit when safety in the event of a failure is further improved. [Figure 23A] This diagram shows the configuration of a voltage generation circuit and its surrounding circuits when applying the voltage generation circuit to a regulator output. [Figure 23B] This diagram shows the voltages and currents at various points in the voltage generation circuit and its surrounding circuitry when the voltage generation circuit is applied to the regulator output. [Figure 24A] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has an operational amplifier terminal protection circuit. [Figure 24B] This diagram shows the output voltage of a voltage generation circuit when the voltage generation circuit has an operational amplifier terminal protection circuit. [Figure 25A] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has a microcontroller-controlled reset circuit. [Figure 25B] This diagram shows the voltages at each position in a voltage generation circuit when the voltage generation circuit has a microcontroller-controlled reset circuit. [Figure 26A] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has an automatic reset circuit. [Figure 26B] A diagram showing the voltages at each position in a voltage generation circuit when the voltage generation circuit has an automatic reset circuit. [Figure 27A] This diagram shows the voltage generation circuit when it is powered off, with an automatic reset circuit, and illustrates a portion of the voltage generation circuit. [Figure 27B] This diagram shows the voltage generation circuit when it is powered off, with an automatic reset circuit, and illustrates the voltages and currents at various points in the voltage generation circuit. [Figure 28] This diagram shows the power-on state when the voltage generation circuit has an automatic reset circuit, and illustrates the voltages and currents at various points in the voltage generation circuit. [Figure 29A] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has a microcontroller-controlled discharge circuit. [Figure 29B] This diagram shows the voltages at various points in a voltage generation circuit when the voltage generation circuit has a microcontroller-controlled discharge circuit. [Figure 30A] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has an automatic discharge circuit. [Figure 30B] A diagram showing the voltages at each position in a voltage generation circuit when the voltage generation circuit has an automatic discharge circuit. [Figure 31] A diagram showing the configuration of a voltage generation circuit in another case where the voltage generation circuit has an automatic discharge circuit. [Figure 32] A diagram showing the voltages at each position of the voltage generation circuit in another case where the voltage generation circuit has an automatic discharge circuit. [Figure 33] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has a microcontroller-controlled reset circuit. [Figure 34] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has a microcontroller-controlled discharge circuit. [Figure 35] This diagram shows the configuration of a voltage generation circuit in another case where the voltage generation circuit has a microcontroller-controlled discharge circuit. [Figure 36] This diagram shows the configuration of a voltage generation circuit when the voltage generation circuit has an automatic discharge circuit. [Figure 37]A diagram showing the configuration of a voltage generation circuit in another case where the voltage generation circuit has an automatic discharge circuit. [Figure 38] This diagram shows the input voltages when the voltage generation circuit has an automatic discharge circuit K7A and when it has an automatic discharge circuit K7B. [Figure 39] This diagram shows the output voltage Vout when the voltage generation circuit has an automatic discharge circuit K7A, when it has an automatic discharge circuit K7B, and when it does not have an automatic discharge circuit. [Modes for carrying out the invention]

[0009] The following describes in detail embodiments of the voltage generation circuit disclosed herein, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0010] (Knowledge that forms the basis of this disclosure) Figure 1 shows the configuration of voltage generation circuit 1X as a comparative example. Figure 2A shows the input voltage of voltage generation circuit 1X and the change in voltage at point A. Figure 2B shows the current flowing from resistor R20 to capacitor C20 in voltage generation circuit 1X. Figure 2C shows the relationship between the gain and frequency of voltage generation circuit 1X.

[0011] Voltage generation circuit 1X has resistors R20 and R21 and capacitor C20. Resistor R20 has terminals tR201 and tR202. Resistor R21 has terminals tR211 and tR212. Capacitor C20 has terminals tC201 and tC202. Terminals tR202, tR211, and tC201 are connected at point A. The input voltage Vin is, for example, 8V. The resistance values ​​of resistors R20 and R21 are equal, for example, 4.7kΩ. In this case, the input voltage Vin is divided by resistors R20 and R21, and the output voltage Vout becomes 4V.

[0012] As shown in Figure 2A, the voltage at point A in the voltage generation circuit 1X is the output voltage Vout, which changes more smoothly than the input voltage Vin. This is because charge is supplied to the capacitor C20 via the resistor R20, and as shown in Figure 2B, the supply of current I10 from the power supply to the capacitor C20 is limited by the resistor R20. To reduce the time t required for the voltage at point A to stabilize, it is desirable to reduce the capacitance of the capacitor C20 and the resistance of the resistor R20, as t = CR. On the other hand, as shown in Figure 2C, the gain in the voltage generation circuit 1X decreases in the frequency range higher than the cutoff frequency fc. Therefore, to reduce the noise in the voltage generation circuit 1X, i.e., to reduce the gain, it is better to have a smaller cutoff frequency fc, so it is desirable to increase the capacitance of the capacitor C20 and the resistance of the resistor R20, as fc = 1 / 2πCR. In other words, there is a dilemma: if you try to reduce the noise, the time t required for the voltage at point A to stabilize increases, and if you try to reduce the time t required for the voltage at point A to stabilize increases the noise.

[0013] The following embodiment describes a voltage generation circuit that can reduce noise and stabilize the output voltage at high speed, even when generating the output voltage using a capacitor.

[0014] (Embodiment) Figure 3A shows a first example of the configuration of the voltage generation circuit 1 according to an embodiment of the present disclosure. Figure 3B shows a second example of the configuration of the voltage generation circuit 1.

[0015] As shown in Figure 3A, the voltage generation circuit 1 has a resistance divider circuit K0 and an add-on circuit K1. The resistance divider circuit K0 has the same configuration as the voltage generation circuit 1X.

[0016] Specifically, the resistor divider circuit K0 has a voltage input terminal Vin, a voltage output terminal Vout, a resistor R1, a resistor R2, and a capacitor C1. The voltage input terminal Vin is the terminal to which the input voltage is input. The voltage output terminal Vout is the terminal to which the output voltage is output. Resistor R1 has terminals tR11 and tR12. Resistor R1 is an example of a first resistor. Resistor R2 has terminals tR21 and tR22. Resistor R2 is an example of a second resistor. Capacitor C1 has terminals tC11 and tC12. Capacitor C1 is an example of a first capacitor.

[0017] Terminal tR11 is electrically connected to the voltage input terminal Vin. Terminal tR11 is an example of a first terminal. Terminal tR12 is electrically connected to terminals tR21, tC11, and the voltage output terminal Vout. Terminal tR12 is an example of a second terminal. Terminal tR21 is electrically connected to terminals tR12, tC11, and the voltage output terminal Vout. Terminal tR22 is electrically connected to ground potential, i.e., earth. Terminal tC11 is electrically connected to terminal tR21 and the voltage output terminal Vout. Terminal tC12 is electrically connected to ground potential. Note that the connection point between resistors R1 and R2 is point A.

[0018] The additional circuit K1 is a circuit added to the resistor divider circuit K0. The additional circuit K1 is an example of the first circuit. The additional circuit K1 has at least a charging circuit KA. The additional circuit K1 may also have a stop circuit KB. The charging circuit KA is a circuit that charges the capacitor C1. The stop circuit KB is a circuit that stops charging the charging circuit KA.

[0019] The charging circuit KA has resistors R4 and R5, operational amplifier IC1, transistor Q1, and resistor R3. Resistor R3 is an example of a fifth resistor. Transistor Q1 is an example of a first transistor. Transistor Q1 is, for example, an NPN bipolar transistor. Operational amplifier IC1 has an inverting input terminal IC1-, a non-inverting input terminal IC1+, and an output terminal IC1out. Transistor Q1 has a base terminal Q1b, a collector terminal Q1c, and an emitter terminal Q1e. Base terminal Q1b is an example of a first control terminal. Collector terminal Q1c is an example of a first non-control terminal. Emitter terminal Q1e is an example of a second non-control terminal. Resistor R3 has terminals tR31 and tR32. Terminal tR31 is an example of a ninth terminal. Terminal tR32 is an example of a tenth terminal. The inverting input terminal IC1- is electrically connected to terminals tR32, tR12, tR21, tC11, and the voltage output terminal Vout. The base terminal Q1b is electrically connected to the output terminal IC1out. The collector terminal Q1c is electrically connected to the power supply terminal and voltage input terminal Vin of op-amp IC1. The emitter terminal Q1e is electrically connected to terminal tR31.

[0020] The stop circuit KB has resistors R4, R5, and R6, and transistor Q2. Resistor R4 is an example of a third resistor. Resistor R5 is an example of a fourth resistor. Resistor R6 is an example of a sixth resistor. Transistor Q2 is an example of a second transistor. Transistor Q2 is, for example, a PNP type bipolar transistor. Resistor R4 has terminals tR41 and tR42. Terminal tR41 is an example of the 5th terminal. Terminal tR42 is an example of the 6th terminal. Resistor R5 has terminals tR51 and tR52. Terminal tR51 is an example of the 7th terminal. Terminal tR52 is an example of the 8th terminal. Resistor R6 has terminals tR61 and tR62. Terminal tR61 is an example of the 11th terminal. Terminal tR62 is an example of the 12th terminal. Transistor Q2 has a base terminal Q2b, a collector terminal Q2c, and an emitter terminal Q2e. Base terminal Q2b is an example of the 2nd controlled terminal. Collector terminal Q2c is an example of the 3rd uncontrolled terminal. Emitter terminal Q2e is an example of the 4th uncontrolled terminal.

[0021] Terminal tR41 is electrically connected to the voltage input terminal Vin. Terminal tR42 is electrically connected to terminal tR51 and terminal tR61 and the non-inverting input terminal IC1+. Note that the connection point between resistors R4 and R5 and the non-inverting input terminal IC1+ is point B. Terminal tR52 is electrically connected to ground potential. Base terminal Q2b is electrically connected to output terminal IC1out and base terminal Q1b. Collector terminal Q2c is electrically connected to ground potential. Emitter terminal Q2e is electrically connected to terminal tR62.

[0022] In Figure 3A, the resistance value of resistor R1 is, for example, 4.7 (kΩ). The resistance value of resistor R2 is, for example, 4.7 (kΩ). The resistance value of resistor R3 is, for example, 200 (Ω). The resistance value of resistor R4 is, for example, 4.7 (kΩ). The resistance value of resistor R5 is, for example, 4.7 (kΩ). The resistance value of resistor R6 is, for example, 4.7 (kΩ). The capacitance value of capacitor C1 is, for example, 220 (μF). Note that the specific resistance and capacitance values ​​for each of these elements are examples only. If similar elements are shown in other drawings, their resistance and capacitance values ​​may be set to the same or different values ​​within the range intended in the embodiment.

[0023] The voltage generation circuit 1 in Figure 3B is the voltage generation circuit 1 in Figure 3A with the addition of a voltage follower. A voltage follower is a circuit that makes the power supply output a low impedance output. The voltage follower includes an operational amplifier IC2. The operational amplifier IC2 has an inverting input terminal IC2-, a non-inverting input terminal IC2+, and an output terminal IC2out. The inverting input terminal IC2-, the output terminal IC2out, and the voltage output terminal Vout are electrically connected. The non-inverting input terminal IC2+, terminals tC11, tR12, tR21, and tR32 are electrically connected to the inverting input terminal IC1-.

[0024] Next, the operation of the voltage generation circuit 1 in Figure 3A will be explained. In this example, a voltage of 8V is input to the voltage input terminal Vin.

[0025] Figure 4 shows the voltage at each point in the voltage generation circuit 1. The timings (1) to (5) in Figure 4 refer to the timings of the operations (1) to (5) described below.

[0026] First, the resistance values ​​of resistors R1, R2, R4, and R5 are set so that the voltage at point A and point B are the same. Here, the ratio of resistance values ​​R1, R2, R4, and R5 is 1:1.

[0027] (1) As shown in Figure 4, when an input voltage of 8V is applied to the voltage input terminal Vin, the voltage at point B instantly stabilizes at, for example, 4V. This is because capacitor C1 is not involved in the voltage at point B.

[0028] (2) Next, the operational amplifier IC1 compares the voltage VA at point A with the voltage VB at point B. Since the voltage VB at point B is higher than the voltage VA at point A, the operational amplifier IC1 outputs a high voltage, for example, 8V. When the output voltage of the operational amplifier IC1 is high, transistor Q2 is turned off.

[0029] (3) Then, transistor Q1 turns on, and charge is supplied to capacitor C1 via resistor R3. In this case, the smaller the resistance value of resistor R3, the more rapidly the voltage at point A rises.

[0030] When the voltage at point A increases, the voltage output from the voltage output terminal Vout also increases.

[0031] (4) When the voltage at point A rises and the voltage VA at point A becomes higher than the voltage VB at point B, the operational amplifier IC1 outputs a low voltage, for example 0V, from its output terminal IC1out. As a result, transistor Q1 turns off, and capacitor C1 is no longer supplied with charge.

[0032] (5) Furthermore, the low voltage from the output terminal IC1out is input to the base terminal Q2b of transistor Q2, causing transistor Q2 to turn on. As a result, point B is electrically connected to ground via resistor R6 and transistor Q2, causing the voltage VB at point B to decrease. This makes it easier to maintain a state where the voltage VA at point A is higher than the voltage VB at point B. During this time, the charging circuit KA does not operate.

[0033] In other words, the operational amplifier IC1 compares the non-inverting input voltage input to the non-inverting input terminal IC1+ with the inverting input voltage input to the inverting input terminal IC1-. The non-inverting input voltage is the voltage at the non-inverting input terminal IC1+. The inverting input voltage is the voltage at the inverting input terminal IC1-. If the non-inverting input voltage is less than the inverting input voltage, the operational amplifier IC1 outputs an on-voltage from the output terminal IC1out to turn on transistor Q1. If the non-inverting input voltage is greater than the inverting input voltage, the operational amplifier IC1 outputs an off-voltage from the output terminal IC1out to turn off transistor Q1.

[0034] Furthermore, even if the voltage VA at point A stabilizes at a level higher than the voltage VB at point B, the voltage at the voltage input terminal Vin may fluctuate due to external noise or connected devices. For example, as shown in (6), if the input voltage Vin fluctuates, the voltage VA at point A and the voltage VB at point B may also fluctuate. The voltage VB at point B is more susceptible to fluctuations from the input voltage Vin than the voltage VA at point A. This is because the voltage VA at point A is relatively stable due to the electrical connection of capacitor C1 at point A. Therefore, fluctuations in the input voltage Vin can easily change the relative magnitudes of the voltage VA at point A and the voltage VB at point B, potentially causing frequent changes in the output voltage of the operational amplifier IC1. This can lead to fluctuations in the output voltage Vout. In this embodiment, the voltage generation circuit 1 includes a stop circuit KB, which makes it easier to maintain a state where the voltage VA at point A is higher than the voltage VB at point B. As a result, once the voltage at the voltage output terminal Vout stabilizes at a desired voltage, for example, 4V, the voltage generation circuit 1 can maintain the voltage at the voltage output terminal Vout in a stable state. This series of operations is the same in the case of voltage generation circuit 1 shown in Figure 3B.

[0035] Next, we will explain the performance of the voltage generation circuit 1.

[0036] Figure 5A shows the voltages at the voltage input terminal Vin and voltage output terminal Vout of the voltage generation circuit 1X. Figure 5B shows the amplitude spectrum of the voltages at the voltage input terminal Vin and voltage output terminal Vout of the voltage generation circuit 1X. Figure 6A shows the voltages at the voltage input terminal Vin and voltage output terminal Vout of the voltage generation circuit 1. Figure 6B shows the amplitude spectrum of the voltages at the voltage input terminal Vin and voltage output terminal Vout of the voltage generation circuit 1.

[0037] As shown in Figure 5A, in voltage generation circuit 1X, it takes time for the voltage at the voltage output terminal Vout to stabilize. Here, it takes about 1.8 seconds for the voltage to stabilize. On the other hand, as shown in Figure 6A, in voltage generation circuit 1, the voltage at the voltage output terminal Vout stabilizes quickly. Here, the time for the voltage to stabilize is about 40 milliseconds. Meanwhile, as shown in Figures 5B and 6B, there is almost no change in the amplitude spectrum of each voltage between voltage generation circuit 1X and voltage generation circuit 1X. In other words, there is almost no change in the amount of noise contained in the voltages at the voltage input terminal Vin and the voltage output terminal Vout. Therefore, voltage generation circuit 1 can stabilize the voltage at the voltage output terminal Vout at high speed while effectively reducing noise.

[0038] Figure 7 shows the configuration of a voltage generation circuit when an FET is used as the transistor.

[0039] As shown in Figure 7, transistors Q1 and Q2 in the voltage generation circuit 1 of Figure 3A may be replaced with FETs, or field-effect transistors. FET stands for Field-effect transistor.

[0040] Transistor Q1 may be replaced with transistor U1 such that the base terminal Q1b, collector terminal Q1c, and emitter terminal Q1e of transistor Q1 correspond to the gate terminal U1g, drain terminal U1d, and source terminal U1s of transistor U1, which is an FET. Transistor U1 is, for example, an N-channel FET. Similarly, transistor Q2 may be replaced with transistor U2 such that the base terminal Q2b, collector terminal Q2c, and emitter terminal Q2e of transistor Q2 correspond to the gate terminal U2g, drain terminal U2d, and source terminal U2s of transistor U2, which is an FET. Transistor U2 is, for example, a P-channel FET. Likewise, transistors Q1 and Q2 in the voltage generation circuit 1 of Figure 3B may be replaced with FET transistors U1 and U2.

[0041] Next, we will describe the case where the voltage generation circuit 1 has a bias power supply circuit K2 instead of a resistor divider circuit K0.

[0042] Figure 8 shows the case where the voltage generation circuit 1 includes a bias power supply circuit K2 and an additional circuit K1A. In Figure 8, components similar to those in the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified. The voltage generation circuit 1 with the bias power supply circuit K2 is also referred to as voltage generation circuit 1B.

[0043] The bias power supply circuit K2 has resistors R7 and R8, capacitor C2, resistors R9 and R10, and operational amplifier IC2. Resistor R7 has terminals tR71 and tR72. Resistor R8 has terminals tR81 and tR82. Capacitor C2 has terminals tC21 and tC22. Resistor R9 has terminals tR91 and tR92. Resistor R10 has terminals tR101 and tR102. Operational amplifier IC2 has an inverting input terminal IC2-, a non-inverting input terminal IC2+, and an output terminal IC2out.

[0044] Terminal tR71, terminal tC21, and voltage input terminal Vin are electrically connected. Terminal tR72, terminal tR81, and non-inverting input terminal IC2+ are electrically connected. Terminal tR82 is electrically connected to ground potential. Terminal tC22 and terminal tR91 are electrically connected. Note that the connection point between terminal tC22 and terminal tR91 is noise2 point. Terminal tR92, terminal tR101, and inverting input terminal IC2- are electrically connected. Terminal tR102, output terminal IC2out, voltage output terminal Vout, and inverting input terminal IC1- are electrically connected.

[0045] Furthermore, the additional circuit K1A in Figure 8 has resistors R12 and Rm in addition to the configuration of additional circuit K1. Resistor R12 has terminals tR121 and tR122. Resistor Rm has terminals tRm1 and tRm2. Terminals tR121, tR91, tC22, and Noise2 are electrically connected. Terminal tR122 is electrically connected to collector terminal Q1c. Terminal tRm1 is electrically connected to base terminal Q1b. Terminal tRm2 is electrically connected to output terminal IC1out and base terminal Q2b.

[0046] Figure 8 illustrates the case where transistors Q1 and Q2 are bipolar transistors. In this case, a current-limiting resistor Rm is provided between the base terminal Q1b of transistor Q1 and the output terminal IC1out of operational amplifier IC1. Note that transistors Q1 and Q2 may be replaced with FET transistors. In this case, the resistor Rm shown in Figure 8 does not need to be provided.

[0047] In Figure 8, the resistance value of resistor R4 is, for example, 4.7 (kΩ). The resistance value of resistor R5 is, for example, 4.7 (kΩ). The resistance value of resistor R6 is, for example, 4.7 (kΩ). The resistance value of resistor R7 is, for example, 10 (kΩ). The resistance value of resistor R8 is, for example, 10 (kΩ). The resistance value of resistor R9 is, for example, 4.7 (kΩ). The resistance value of resistor R10 is, for example, 4.7 (kΩ). The resistance value of resistor Rm is, for example, 10 (kΩ). The resistance value of resistor R12 is, for example, 200 (Ω). The capacitance value of capacitor C1 is, for example, 220 (μF). Note that the specific resistance and capacitance values ​​for each of these elements are examples. If similar elements are shown in other drawings, their resistance and capacitance values ​​may be set to the same or different values ​​within the range intended in the embodiment.

[0048] The effects of this embodiment will be explained using Figure 9. Figure 9 shows the change in voltage at point A when the capacitor C20 of voltage generation circuit 1X is 2200 μF and the capacitor C1 of voltage generation circuit 1 is 2200 μF.

[0049] As shown in Figure 9, in voltage generation circuit 1X, it takes, for example, 20 seconds or more for the voltage to stabilize. On the other hand, Figure 9 shows that in voltage generation circuit 1, the output voltage stabilizes quickly.

[0050] Next, we will explain how to design the constants of each circuit element in the voltage generation circuit 1.

[0051] 1. Resistor R1, Resistor R2, Capacitor C1

[0052] First, let's explain the constants of resistors R1 and R2, and capacitor C1. If we let Vin (V) be the input voltage input from the voltage input terminal Vin, Vo (V) be the output voltage output from the voltage output terminal Vout, and fc (Hz) be the cutoff frequency of the low-pass filter composed of resistors R1 and R2 and capacitor C1, then the following relationship holds. Below, the names of resistors will also be expressed as resistance values ​​in the formulas, and the names of capacitors will also be used as capacitance values ​​in the formulas.

[0053]

number

[0054] Lowering the cutoff frequency fc increases the noise reduction effect of the voltage generation circuit 1. In other words, the larger the values ​​of resistor R1 and capacitor C1, the greater the noise reduction effect, but the longer it takes for the output voltage Vout to stabilize. Also, higher resistance values ​​make the circuit more susceptible to external radiated noise, and larger capacitance values ​​for capacitor C1 increase the size of the components. Therefore, the resistance values ​​of resistors R1 and R2 should be set to 330Ω to 10kΩ, and the capacitance value of capacitor C1 should be set to 100uF to 2200uF.

[0055] 2. Transistor Q1, resistor R3

[0056] Next, the constants of transistor Q1 and resistor R3 will be explained. Figure 10 is a diagram comparing information regarding resistor R3. In Figure 10, the time it takes for the output voltage of the voltage generation circuit 1 to stabilize, the inrush current flowing through capacitor C1 when transistor Q1 is turned on, and the load on transistor Q1 are compared according to the magnitude of the constant of resistor R3. Figure 11 is a diagram showing the charging current characteristics from resistor R3 to capacitor C1. Figure 12 is a diagram showing the charging waveform and equivalent rectangular waveform of the charging current of capacitor C1.

[0057] As shown in Figure 10, the voltage generation circuit 1 can speed up the rise of the output voltage Vout, i.e., shorten the startup time, by increasing the inrush current flowing into capacitor C1 at the moment transistor Q1 is turned on. The inrush current is represented by the peak value Ip in Figure 11. On the other hand, as the inrush current increases, the load on transistor Q1 and resistor R3 increases. This load includes, for example, a thermal load. The charging current of capacitor C1 takes its maximum value as an inrush current at the moment transistor Q1 is turned on, as shown in Figure 11, and has a peak value Ip. The peak value Ip can be calculated, for example, as follows.

[0058]

number

[0059] In other words, the constant of resistor R3 must be determined considering the tolerances of resistor R1, transistor Q1, capacitor C1, etc. First, when supplying charge from resistor R3 to capacitor C1, the current waveform is as shown in Figure 11. This is called the charging waveform, as it represents the charging current. As shown in Figure 12, when the charging current is a predetermined allowable current, the charging waveform can be replaced with an equivalent rectangular waveform determined by the peak value Ip and the time constant τ, and used in calculations of allowable current and power. The time constant τ indicates the duration of charging. The time constant τ can be calculated, for example, as follows. τ=C1·R3 (s)...Equation (2)

[0060] Next, considering the allowable current of transistor Q1, the peak value Ip is determined, and the constant of resistor R3 is determined.

[0061] If transistor Q1 is, for example, a transistor with a size of about 2 mm square, the allowable current for one pulse of 100 msec or less is 80 mA when the input voltage Vin is, for example, about 8 V. Furthermore, if the operating environment is a high-temperature environment and a 50% derating is considered, the allowable current for one pulse of 100 msec or less is, for example, 40 mA. From the above, the constant of resistor R3 that results in a peak value Ip of 40 mA can be calculated to be 200 Ω from equation (1).

[0062] Next, determine the component size based on the power consumed by resistor R3.

[0063] The calculation for determining power P from the equivalent rectangular waveform in Figure 12 can be expressed, for example, by equation (3). Here, by rearranging equation (3) based on equations (1) and (2), we obtain equation (4). Therefore, power P can be calculated from the input voltage Vin and the capacitance value of capacitor C1, regardless of the value of resistor R3.

[0064]

number

[0065] Therefore, assuming the input voltage Vin is 8V and the capacitance of capacitor C2 is 220uF, from equation (4), the power P consumed by resistor R3 is 0.00704W. If resistor R3 is a typical thick-film chip resistor, the power rating of a 1005 size resistor is 0.1W, so it can be determined that there is no problem.

[0066]

number

[0067] When considering the allowable current, other methods can be considered to obtain a more accurate result. In the calculation described above, the equivalent rectangular waveform was used when the charge supply to capacitor C1 was infinite for an infinite amount of time. However, since the voltage generation circuit 1 stops supplying charge to capacitor C1 when the set output voltage Vout is reached, it is preferable to perform the calculation using the equivalent rectangular waveform for a finite time. If the charging duration is considered to be the time obtained by multiplying the ratio of the output voltage Vout to the input voltage Vin by the time constant τ, the peak value Ip and the duration can be used for more accurate current and power calculations. In the previous example, the output voltage Vout is 4V and the input voltage Vin is 8V, so Vo / Vin is 0.5, and the current value can be considered to be halved. That is, although the resistance value of resistor R3 was set to 200Ω with a target of 40mA, it could also be set to 100Ω with a target of 80mA. Furthermore, the power calculation can be performed using equation (5), which allows for calculations that are more in line with the actual situation.

[0068]

number

[0069] An example of calculating current and power using an equivalent rectangular waveform over a finite time is explained using Figure 13. Figure 13 shows the charging waveform and equivalent rectangular waveform of capacitor C1. In the example shown in Figure 13, the voltage generation circuit 1 stops supplying charge to capacitor C1 when the current reaches 0.5Ip. Therefore, the current becomes 0 thereafter.

[0070]

number

[0071] Next, we will explain the relationship between the output voltage / input voltage and the reduction factor K.

[0072] The reduction factor K is the value of (1-(Vout / Vin)) described in equation (5). 2 In other words, the reduction factor takes a value between 0 and 1. That is, the smaller the reduction factor K, the greater the degree of reduction and the smaller the power P.

[0073] Figure 14 is a table showing the relationship between output voltage / input voltage and reduction factor.

[0074] As can be seen from the relationship between the output voltage / input voltage and the reduction factor K in Figure 14, the reduction is greater when the output voltage Vout is close to the input voltage Vin. For example, even if the output voltage Vout is half the voltage of the input voltage Vin, it can be seen that the power consumption P can be reduced by 75%.

[0075] 3. Resistor R4, Resistor R5, Resistor R6

[0076] Next, resistors R4, R5, and R6 will be explained.

[0077] Figure 15A is a diagram illustrating the dead voltage. Figure 15B is a diagram illustrating the Toffon time when the power is turned on again.

[0078] Resistors R4 and R5 generate a reference voltage Vref to stop supplying charge to capacitor C1 when the output voltage Vout reaches a predetermined voltage after the voltage generation circuit 1 is powered on. The voltage generated as the reference voltage Vref is the voltage obtained by dividing the power supply voltage, i.e., the input voltage Vin, by the resistance values ​​of resistors R4 and R5. An example of the relationship between the reference voltage Vref is shown in equation (6).

[0079]

number

[0080] Considering that current always flows through resistors R4 and R5, the resistance values ​​of resistors R4 and R5 should be in the range of 1kΩ to 33kΩ. Additionally, resistor R6 provides a dead voltage V to prevent the supply of charge to capacitor C1 from starting again due to a temporary fluctuation in the input voltage Vin after the current supply to capacitor C1 has been stopped. Lis the resistor that determines it. The temporary fluctuation of the input voltage Vin is shown in Fig. 15A. The dead voltage V L may be calculated based on the assumed fluctuation range ΔVin of the input voltage Vin and the time Toffon at the time of power supply restart.

[0081] As described above, the fluctuation of the input voltage Vin is caused by external noise or the like. Also, power supply restart is assumed to be a case where the application of the input voltage Vin to the voltage generation circuit 1 is once stopped and then input again, that is, applied again. The relationship between the dead voltage V L and the fluctuation range Δvin can be expressed, for example, by Equation (7).

[0082] [Number]

[0083] When determining the dead voltage V L with a margin added, the resistance value of the resistor R6 can be expressed, for example, by the following Equation (8). L Here, when determining the dead voltage V

[0084] [Number]

[0085] Here, it is necessary to consider the time Toffon for restarting the power supply based on the calculated dead voltage V L '. A plurality of examples of the time Toffon are shown in Fig. 15B. The time Toffon should be as small as possible.

[0086] When the voltage generation circuit 1 increases the dead voltage V L ', it can reduce the malfunction due to power supply fluctuation, that is, the fluctuation of the input voltage Vin. On the other hand, after the power supply is turned off, the voltage generation circuit 1 cannot restart the power supply until the output voltage Vout drops by the amount of the dead voltage V L '. The criterion for restart can be expressed, for example, by the following Equation (9).

[0087]

number

[0088] For example, suppose the capacitance of capacitor C1 is 220uF, the constant of resistor R2 is 4.7kΩ, and the reference voltage Vref is 4V, and the dead voltage V L When the voltage is 1.34V, the time Toffon, or in other words, time Toffon1, is 0.42s. In contrast, the dead voltage V L If we set ' to twice this value, 2.68V, the time Toffon, or in other words, time Toffon2, is 1.146s, which is 2.73 times Toffon1 = 0.42s. In other words, the dead voltage V L It can be understood that increasing the value of ' increases the time Toffon.

[0089] 4. Transistor Q2

[0090] Voltage generation circuit 1 changes the reference voltage Vref by operating transistor Q2 and supplying current to resistor R6 based on the output signal of op-amp IC1. At this time, the current flowing through resistor R6 becomes the collector current of transistor Q2, so it is desirable to select transistor Q2 based on the current flowing through resistor R6. Transistor Q2 is a pnp bipolar transistor used in the switching region, so it is assumed to have a small on-resistance and the current is calculated accordingly. The current flowing through resistor R6 when transistor Q2 is turned on can be expressed by equation (10), for example.

[0091]

number

[0092] For example, if the reference voltage Vref is 4V, the dead voltage V L Current I when the voltage is 1.34V and the resistance value of resistor R6 is 4.7kΩ R6 This is calculated to be 0.566mA. Therefore, it is best to select transistor Q2 based on its collector current rating.

[0093] 5. Operational amplifier IC1

[0094] The operational amplifier IC1 compares the output voltage Vout (voltage at point A) with the reference voltage Vref (voltage at point B). If the output voltage Vout is smaller, the operational amplifier IC1 outputs a positive output (high voltage), and if the output voltage Vout is larger, it outputs a 0V output (low voltage). When the operational amplifier IC1 is outputting a positive output, it supplies base current to transistor Q1 and controls the voltage so that transistor Q1 can be used in the saturation region. In this case, the operational amplifier IC1 is selected to supply a current of 1 / hfe to the peak value Ip of the charging waveform used when resistor R3 was designed as the collector current flowing through transistor Q1. For a transistor Q1 of about 2 mm square, hfe is 300, so the current Ip / hfe is about 133uA. Here, hfe is the current amplification factor when the emitter is common.

[0095] Furthermore, when the op-amp IC1 is outputting 0V, it draws the base current from transistor Q2. Similarly, for transistor Q2, op-amp IC1 is selected that can draw a current of 1 / hfe relative to the collector current of transistor Q2. In the case of transistor Q2, which is about 2mm square, the hfe is 300, so the current flowing through resistor R6 is I R6 In that case, I R6 The current at / hfe is approximately 1.9uA. For op-amp IC1, a general voltage feedback type op-amp can be selected, for example.

[0096] On the other hand, if the input voltage Vin is rapidly turned off, i.e., no longer applied, the potential at the inverting input terminal IC1- of the op-amp IC1 will be higher than that at the power supply terminal of the op-amp IC1 due to the charge remaining in capacitor C1. Therefore, it is necessary to select an op-amp IC1 that takes its absolute ratings into consideration. If the op-amp IC1 exceeds its absolute ratings, measures can be taken to prevent the input voltage Vin from rapidly turning off, or a Schottky barrier diode can be inserted. Details about Schottky barrier diodes will be described later.

[0097] <Modified Voltage Generation Circuit> Next, an arrangement circuit, which is a modified version of the voltage generation circuit 1, will be described. The arrangement circuit may also be applied to the voltage generation circuit 1B.

[0098] First, let's explain the positive voltage output from a positive power supply.

[0099] Figure 16 shows the output voltage Vout when a positive voltage is output by a positive power supply in the voltage generation circuit 1. This voltage generation circuit 1 is, for example, the voltage generation circuit 1 in Figure 3A. In Figure 16, the horizontal axis represents time and the vertical axis represents the voltage value.

[0100] Figure 16 compares the case with and without the additional circuit K1. Referring to Figure 16, the voltage generation circuit 1 with the additional circuit K1 can achieve stable output voltage Vout more quickly compared to the voltage generation circuit without the additional circuit K1.

[0101] Note that in voltage generation circuit 1, the operational amplifier IC1 may be replaced with a comparator. The operational amplifier IC1 amplifies the difference between the input to the non-inverting input terminal IC1+ and the input to the inverting input terminal IC1-. If the voltage input to the non-inverting input terminal IC1+ and the voltage input to the inverting input terminal IC1- are the same, the operational amplifier IC1 outputs 0V. In contrast, the comparator compares the voltage input to the non-inverting input terminal IC1+ and the voltage input to the inverting input terminal IC1- and outputs a High voltage or a Low voltage. Even when a comparator is used instead of the operational amplifier IC1 in voltage generation circuit 1, the result will be as shown in Figure 16.

[0102] Next, we will explain negative voltage output from a negative power supply.

[0103] The case in which a negative voltage is output by a negative power supply in the voltage generation circuit 1 will be explained using Figures 17A and 17B. Figure 17A shows the configuration of the voltage generation circuit 1. In Figure 17A, components similar to those in the voltage generation circuit 1 shown in other figures are given the same reference numerals, and their explanations are omitted or simplified. Figure 17B shows the output voltage Vout. In Figure 17B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0104] In Figure 17A, the input voltage Vin is, for example, -8V, and the output voltage Vout is, for example, -4V. Even in this case, the voltage generation circuit 1 with the additional circuit K1 can achieve stability of the output voltage Vout more quickly than the voltage generation circuit without the additional circuit K1.

[0105] Next, we will describe the first example of a positive voltage output in a dual power supply circuit.

[0106] Figures 18A and 18B show the case where the voltage generation circuit 1, acting as a dual power supply circuit, outputs a positive voltage. Figure 18A shows the configuration of the voltage generation circuit 1. In Figure 18A, components similar to those shown in other figures of the voltage generation circuit 1 are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 18B shows the output voltage Vout. In Figure 18B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0107] Voltage generation circuit 1 receives, for example, 8V as a positive input voltage Vin, for example, -8V as a negative input voltage V-, and outputs, for example, 4V as an output voltage Vout. Even in this case, voltage generation circuit 1 can quickly achieve stability of the output voltage Vout compared to a voltage generation circuit without the additional circuit K1.

[0108] Next, we will describe a second example of a positive voltage output in a dual power supply circuit.

[0109] Using Figures 19A and 19B, we will explain another case in which the voltage generation circuit 1, as both power supply voltages, outputs a positive voltage. Figure 19A is a diagram showing the configuration of the voltage generation circuit 1. In Figure 19A, components similar to those shown in other diagrams of the voltage generation circuit 1 are given the same reference numerals, and their explanations are omitted or simplified. Figure 19B is a diagram showing the output voltage Vout. In Figure 19B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0110] Voltage generation circuit 1 takes a positive input voltage Vin of, for example, 8V, a negative input voltage V- of, for example, -8V, and outputs an output voltage Vout of, for example, 4V. The collector terminal Q2c, terminals tR52, terminals tR22, and terminal tC12 are electrically connected to the negative voltage V-. In the example shown in Figure 19A, the ratio of the resistance values ​​of resistors R1 and R2, and resistors R4 and R5 are adjusted so that the output voltage Vout is 4V. For example, (resistance of resistor R1) : (resistance of resistor R2) = (resistance of resistor R4) : (resistance of resistor R5) = 1.567 (kΩ) : 4.7 (kΩ). Even in this case, voltage generation circuit 1 can quickly achieve stability of the output voltage Vout compared to a voltage generation circuit without the additional circuit K1.

[0111] Next, we will explain the negative voltage output in a negative power supply circuit.

[0112] The case in which the voltage generation circuit 1, acting as a negative power supply circuit, outputs a negative voltage will be explained using Figures 20A and 20B. Figure 20A shows the configuration of the voltage generation circuit 1. In Figure 20A, components similar to those shown in other figures of the voltage generation circuit 1 are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 20B shows the output voltage Vout. In Figure 20B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0113] Voltage generation circuit 1 receives, for example, -8V as a negative input voltage Vin, for example, 8V as a positive input voltage V+, and outputs, for example, -4V as an output voltage Vout. The input voltage V+ is input as the positive power supply voltage of op-amp IC1. Even in this case, voltage generation circuit 1 can achieve output voltage Vout stability more quickly than voltage generation circuit without the additional circuit K1.

[0114] Next, we will explain the negative voltage output in a dual power supply circuit.

[0115] The case in which the voltage generation circuit 1, acting as a dual power supply circuit, outputs a negative voltage will be explained using Figures 21A and 21B. Figure 21A shows the configuration of the voltage generation circuit 1. In Figure 21A, components similar to those shown in other figures of the voltage generation circuit 1 are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 21B shows the output voltage Vout. In Figure 21B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0116] Voltage generation circuit 1 takes a positive input voltage Vin of, for example, 8V, a negative input voltage V- of, for example, -8V, and outputs an output voltage Vout of, for example, -4V. The collector terminal Q2c, terminals tR52, terminals tR22, and terminal tC12 are electrically connected to the negative voltage V-. In the example shown in Figure 21A, the ratio of the resistance values ​​of resistors R1 and R2, and resistors R4 and R5 are adjusted so that the output voltage Vout is -4V. For example, (resistance of resistor R1) : (resistance of resistor R2) = (resistance of resistor R4) : (resistance of resistor R5) = 14.1 (kΩ) : 4.7 (kΩ). Even in this case, voltage generation circuit 1 can quickly achieve stability of the output voltage Vout compared to a voltage generation circuit without the additional circuit K1.

[0117] Next, we will explain how to further improve safety in the event of a failure in the voltage generation circuit 1.

[0118] Figures 22A and 22B are used to explain how to further improve safety in the event of a failure in the voltage generation circuit 1. Figure 22A shows the configuration of the voltage generation circuit 1. In Figure 22A, components similar to those shown in other figures of the voltage generation circuit 1 are given the same reference numerals, and their explanations are omitted or simplified. Figure 22B shows the output voltage Vout. In Figure 22B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0119] In the voltage generation circuit 1 shown in Figure 22A, the input voltage Vin to the resistor divider circuit K0 is the same as in the voltage generation circuit 1 shown in Figure 3A, at 8V, but the input voltage Vop to the add-on circuit K1 is 5.4V. The voltage generation circuit 1 may control the output voltage Vout by using, for example, 5.4V as the minimum input voltage Vop. The minimum input voltage Vop is, for example, the sum of the output voltage Vout, the maximum output voltage of the operational amplifier IC1, and the VBE voltage of the transistor Q1. Note that if the voltage generation circuit 1 has a FET instead of a bipolar transistor, the gate-source voltage Vth is used instead of the VBE voltage.

[0120] If transistor Q1 fails and shorts out, the input voltage Vop is output as the output voltage Vout. If, for example, an input voltage Vin of 8V is used as the input voltage to the add-on circuit K1, and transistor Q1 shorts out, 8V will be output as the output voltage Vout. Since the original output voltage Vout is 4V, a voltage significantly higher than that can lead to failure of the connected device. On the other hand, if input voltage Vop is used as the input voltage to the add-on circuit K1, even if transistor Q1 shorts out, the output voltage Vout will be limited to 5.4V. As a result, the voltage generation circuit 1 can protect the device connected to the output voltage Vout even if transistor Q1 fails and shorts out. Furthermore, the voltage generation circuit 1 in Figure 22A can achieve stable output voltage Vout more quickly compared to a voltage generation circuit without the add-on circuit K1.

[0121] Next, we will explain how to apply voltage generation circuit 1 to the regulator output.

[0122] Figures 23A and 23B illustrate the application of the voltage generation circuit 1 to the regulator output. Figure 23A shows the configuration of the voltage generation circuit 1 and its surrounding circuits. In Figure 23A, components similar to those shown in other figures of the voltage generation circuit 1 are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 23B shows the output voltage Vout, the inrush current to the regulator, and the bypass current passing through the additional circuit K1. In Figure 23B, the horizontal axis represents time, and the vertical axis represents the voltage value or current value.

[0123] Voltage generation circuit 1 in Figure 23A differs from the previous voltage generation circuit 1 in that capacitor Cb is connected to the terminal of resistor R1 that is not connected to resistor R2. The OUT terminal of regulator RG is electrically connected to the voltage input terminal Vin of voltage generation circuit 1. In other words, the output voltage of regulator RG as the regulator output becomes the input voltage Vin of voltage generation circuit 1. Also, the IN terminal of regulator RG is electrically connected to resistor R100. The other terminal of resistor R100 is electrically connected to the voltage input terminal VIN. The voltage input terminal VIN is connected to the voltage input terminal VIN of the additional circuit K1. Resistor R100 is a resistor introduced to explain the inrush current described later, and its resistance value may be significantly smaller than that of resistor R1, etc.

[0124] In Figure 23B, the upper graph shows the output voltage Vout of the voltage generation circuit in Figure 23A without the additional circuit K1, and the output voltage Vout of the voltage generation circuit 1 in Figure 23A, in time series. In this upper graph, the case of the voltage generation circuit without the additional circuit K1 is shown by a dashed line, and the case of Figure 23A is shown by a solid line.

[0125] In Figure 23B, the graph in the middle section shows the current flowing through resistor R100 in time series when the voltage generation circuit of Figure 23A is applied to the regulator output without the additional circuit K1, and when the voltage generation circuit 1 of Figure 23A is applied to the regulator output. The current flowing through resistor R100 corresponds to the inrush current to the regulator. In this middle section graph, the case where the voltage generation circuit 1 of Figure 23A does not have the additional circuit K1 is shown by a dashed line, and the case where the voltage generation circuit 1 of Figure 23A is shown by a solid line.

[0126] In Figure 23B, the lower graph shows the current flowing through resistor R200 in voltage generation circuit 1 of Figure 23A. The current flowing through resistor R200 corresponds to the bypass current passing through the additional circuit K1.

[0127] As shown in Figure 23B, the voltage generation circuit 1 can reduce the inrush current to regulator RG when it is started up. Specifically, as shown in the middle graph of Figure 23B, the voltage generation circuit 1 can reduce the inrush current from, for example, 434mA to 275mA. This is because the voltage input terminal VIN is connected to the voltage input terminal VIN of the add-on circuit K1, so the current is bypassed from the voltage input terminal VIN to the voltage input terminal VIN of the add-on circuit K1. Also, as shown in the upper graph of Figure 23B, the voltage generation circuit 1 can achieve stability of the output voltage Vout more quickly compared to a voltage generation circuit without the add-on circuit K1.

[0128] <Practical Circuit for Voltage Generation Circuit> Next, we will describe the practical circuit of voltage generation circuit 1.

[0129] First, we will describe the case where the voltage generation circuit 1 has an operational amplifier terminal protection circuit.

[0130] The case where the voltage generation circuit 1 has an operational amplifier terminal protection circuit will be explained using Figures 24A and 24B. Figure 24A shows the configuration of the voltage generation circuit 1. In Figure 24A, components similar to those in the configuration of the voltage generation circuit 1 shown in other figures are given the same reference numerals, and their explanations are omitted or simplified. Figure 24B shows the output voltage Vout. In Figure 24B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0131] The operational amplifier terminal protection circuit is a circuit that protects the terminals of operational amplifier IC1, and is, for example, a Schottky barrier diode.

[0132] The voltage generation circuit 1 in Figure 24A includes the voltage generation circuit 1 in Figure 3B and further includes other circuit elements. Specifically, the voltage generation circuit 1 in Figure 24A has an additional circuit K1 which has a Schottky barrier diode D1. The Schottky barrier diode D1 is an example of a diode. The Schottky barrier diode D1 has a cathode terminal tD11 and an anode terminal tD12. The cathode terminal tD11 is electrically connected to terminal tR42 and collector terminal Q1c, etc. The anode terminal tD12 is electrically connected to the inverting input terminal IC1-, terminal tR32 and terminal tC11, etc.

[0133] Furthermore, the voltage generation circuit 1 in Figure 24A has a resistor R11 and a power switch S2. Resistor R11 has terminals tR111 and tR112. Power switch S2 has terminals tSW11 and tSW12. Terminal tR111 is electrically connected to the voltage output terminal Vout, the output terminal IC2out, and the inverting input terminal IC2-. Terminal tR112 is electrically connected to ground potential. Terminal tSW12 is electrically connected to terminal tR11 to the positive power supply terminal, collector terminal Q1c, and cathode terminal tD11 of the operational amplifier IC2. Terminal tSW11 is electrically connected to the voltage input terminal Vin.

[0134] Suppose the voltage generation circuit 1 does not have a Schottky barrier diode D1, and the power supply is suddenly cut off, meaning the input voltage at the voltage input terminal Vin drops sharply. In this case, the voltage at the inverting input terminal IC1- of the operational amplifier IC1 may become higher than the input voltage Vin at the voltage input terminal Vin. As shown in the upper graph of Figure 24B, the voltage at the inverting input terminal IC1- may exceed the maximum rating of the operational amplifier IC1. For example, immediately after power-off, the output voltage Vout may become 4V higher than the input voltage Vin. In that case, the operational amplifier IC1 may fail. In contrast, the voltage generation circuit 1, by having a Schottky barrier diode D1, can avoid the voltage at the inverting input terminal IC1- exceeding the maximum rating of the operational amplifier IC1, as shown in the lower graph of Figure 24B. For example, the voltage generation circuit 1 can maintain an output voltage Vout that is 0.2V higher than the input voltage Vin, even immediately after power-off. The maximum rating of the operational amplifier IC1 may be, for example, 0.3V or 0.7V.

[0135] Note that the Schottky barrier diode D1 may be any other diode, and may be replaced with any other diode that can avoid exceeding the maximum rating of the op-amp IC1 as described above.

[0136] Next, we will describe the case where the voltage generation circuit 1 has a reset circuit.

[0137] Possible reset circuits include microcontroller-controlled reset circuits that reset using control signals from the microcontroller, and automatic reset circuits that reset through the operation of the circuit without using control signals from the microcontroller. The reset circuit may also be included in the additional circuit K1.

[0138] The reset circuit is a circuit that temporarily increases the voltage VB at point B in the add-on circuit K1, thereby creating a state where the voltage VA < voltage VB at point A. This allows the voltage VA < voltage VB even if there is still charge stored in capacitor C1, enabling the charging circuit KA of the add-on circuit K1 to activate earlier. In other words, after the input voltage Vin is turned off once, the reset circuit supplies voltage to the non-inverting input terminal IC1+ and controls the voltage at the non-inverting input terminal IC1+ to be higher than the output voltage Vout.

[0139] First, we will explain the case where the voltage generation circuit 1 has a microcontroller-controlled reset circuit.

[0140] The case in which the voltage generation circuit 1 has a microcontroller-controlled reset circuit K3 will be explained using Figures 25A and 25B. Figure 25A is a diagram showing the configuration of the voltage generation circuit 1. In Figure 25A, components similar to those shown in other diagrams of the voltage generation circuit 1 are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 25B is a diagram showing the voltages at various positions in the voltage generation circuit 1. In Figure 25B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0141] The microcontroller-controlled reset circuit K3 includes resistors R12, R13, and R14, transistors Q3 and Q4, and capacitor C3.

[0142] Resistor R12 has terminals tR121 and tR122. Resistor R13 has terminals tR131 and tR132. Resistor R14 has terminals tR141 and tR142. Transistor Q3 has base terminal Q3b, collector terminal Q3c, and emitter terminal Q3e. Transistor Q4 has base terminal Q4b, collector terminal Q4c, and emitter terminal Q4e. Capacitor C3 has terminals tC31 and tC32.

[0143] Terminals tR121, tR131, tR41, and the voltage input terminal Vin are electrically connected. Terminal tR122 and the collector terminal Q3c are electrically connected. Terminal tR132, the base terminal Q3b, and the collector terminal Q3c are electrically connected. The emitter terminal Q3e, terminals tR42, tR51, tR61, and the non-inverting input terminal IC1+ are electrically connected. The base terminal Q4b, terminal tC31, and terminal tR141 are electrically connected. The emitter terminal Q4e is electrically connected to ground potential. Terminal tC32 is electrically connected to ground potential. Terminal tR142 is electrically connected to the uCOM terminal. The uCOM terminal indicates a terminal to which a signal is input. For example, a signal from a microcontroller is input to the uCOM terminal. A reset control signal may be input here. A reset control signal is an on / off control signal, that is, a signal that alternates between high voltage and low voltage.

[0144] The upper graph in Figure 25B shows the time-series data between the input voltage Vin of the voltage generation circuit 1 with the microcontroller-controlled reset circuit K3 and the voltage at the uCOM terminal, i.e., the reset control signal voltage. The middle graph in Figure 25B shows the time-series data between the output voltage Vout of the voltage generation circuit 1 without the microcontroller-controlled reset circuit K3 and the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1. The lower graph in Figure 25B shows the time-series data between the output voltage Vout of the voltage generation circuit 1 with the microcontroller-controlled reset circuit K3 and the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1.

[0145] In the voltage generation circuit 1, which does not have the microcontroller-controlled reset circuit K3, after the power is cut off, that is, after the input voltage Vin drops sharply, a voltage may remain at the voltage output terminal Vout due to the charge accumulated in capacitor C1. As a result, as shown in the middle graph of Figure 25B, the output voltage Vout drops initially and then gradually increases. Therefore, the next time the voltage generation circuit 1 is started, the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1 will be smaller than the voltage value of the output voltage Vout. Consequently, the additional circuit K1 will not operate, and it may take time to start up the voltage generation circuit 1.

[0146] In contrast, the voltage generation circuit 1 can reset the add-on circuit K1 by connecting the microcontroller-controlled reset circuit K3 to the add-on circuit K1. Specifically, as shown in Figure 25B, the microcontroller-controlled reset circuit K3 can turn on transistor Q3 when the power is started, i.e., when the input voltage Vin is applied, by receiving a reset control signal from the uCOM terminal at the next startup. Then, the combined resistance of resistors R4 and R12 makes it possible to set the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1 to a value higher than the output voltage value, for example, 4V. As a result, the add-on circuit K1 can be started up quickly, and as shown in Figure 25B, the output voltage Vout can be quickly set to a predetermined voltage, for example, 4V, immediately after the power is started up. Note that the reset control signal may be shared with the signal that controls the on / off state of the power switch S2.

[0147] Next, we will describe the case where the voltage generation circuit 1 has an automatic reset circuit K4.

[0148] The case where the voltage generation circuit 1 has an automatic reset circuit K4 will be explained using Figures 26A and 26B. Figure 26A is a diagram of the voltage generation circuit 1. In Figure 26A, components similar to those in the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 26B is a diagram showing the voltages at various positions in the voltage generation circuit 1. In Figure 26B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0149] The automatic reset circuit K4 includes resistors R15, R16, R17, transistor Q5, and capacitor C4.

[0150] Resistor R15 has terminals tR151 and tR152. Resistor R16 has terminals tR161 and tR162. Resistor R17 has terminals tR171 and tR172. Transistor Q5 has base terminal Q5b, collector terminal Q5c, and emitter terminal Q5e. Capacitor C4 has terminals tC41 and tC42.

[0151] Terminal tR151 is electrically connected to the emitter terminal Q5e, terminal tR41, and voltage input terminal Vin. Terminal tR152 is electrically connected to terminal tC41 and terminal tR161. Terminal tR162 is electrically connected to the base terminal Q5b. Terminal tC42 is electrically connected to ground potential. Collector terminal Q5c is electrically connected to terminal tR171. Terminal tR172 is electrically connected to terminal tR42, terminal tR51, terminal tR61, and non-inverting input terminal IC1+.

[0152] The upper graph in Figure 26B shows the input voltage Vin of the voltage generation circuit 1 with the automatic reset circuit K4 in a time series. The middle graph in Figure 26B shows the output voltage Vout of the voltage generation circuit 1 without the automatic reset circuit K4 and the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1 in a time series. The lower graph in Figure 26B shows the output voltage Vout of the voltage generation circuit 1 with the automatic reset circuit K4 and the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1 in a time series.

[0153] In the voltage generation circuit 1, which does not have the automatic reset circuit K4, the output voltage Vout initially decreases and then gradually increases, as shown in the middle graph of Figure 26B. Therefore, the next time the voltage generation circuit 1 is started, the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1 will be smaller than the voltage value of the output voltage Vout. Consequently, the additional circuit K1 will not operate, and it may take time to start up the voltage generation circuit 1. The mechanism for the time it takes to start up is the same as that described for the voltage generation circuit 1, which does not have the microcontroller-controlled reset circuit K3.

[0154] In contrast, the voltage generation circuit 1 can automatically reset the add-on circuit K1 by connecting the automatic reset circuit K4 to the add-on circuit K1. Specifically, the automatic reset circuit K4 is configured to activate transistor Q5 when the power supply of the voltage generation circuit 1 is started. As a result, the combined resistance of resistors R17 and R4 allows the voltage at the non-inverting input terminal IC1+ to be higher than the output voltage value, for example, 4V, as shown in Figure 26B. This allows the add-on circuit K1 to be started quickly, and as shown in Figure 26B, the output voltage Vout can be quickly set to a predetermined voltage, for example, 4V, immediately after the input power supply is started.

[0155] The operation of the voltage generation circuit 1 when the power is turned off, when it has an automatic reset circuit K4, will be explained using Figures 27A and 27B. Figure 27A is a diagram showing a part of the voltage generation circuit 1 from Figure 26A. Figure 27B is a diagram showing the voltages and currents at various positions in the voltage generation circuit 1. In Figure 27B, the horizontal axis represents time and the vertical axis represents the voltage value.

[0156] The upper graph in Figure 27B shows the input voltage Vin of the voltage generation circuit 1 with the automatic reset circuit K4 over time. Here, in particular, it is shown that when the power supply is cut off, the input voltage Vin drops, for example, from 8V to less than 4V. The middle graph in Figure 27B shows the voltage at point C of the voltage generation circuit 1 with the automatic reset circuit K4, the current flowing through resistor R15, and the current flowing through resistor R16 over time. Point C is the connection point between terminals tR152, tC41, and tR161 in the voltage generation circuit 1 in Figure 27A. The lower graph in Figure 27B shows the output voltage Vout of the voltage generation circuit 1 with the automatic reset circuit K4 and the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1 over time.

[0157] When the power to the voltage generation circuit 1 is turned off, the voltage at point D in Figure 27A, i.e., the input voltage Vin, drops, and the charge on capacitor C4 is discharged through resistor R15. As a result, the voltage at point C in Figure 27A drops as shown in Figure 27B. This prepares the voltage generation circuit 1 for the next power-up. Point D is the connection point between terminals tR41, tR151, and emitter terminal Q5e in the voltage generation circuit 1 in Figure 27A.

[0158] The operation of the voltage generation circuit 1 when it is powered on, with the automatic reset circuit K4, will be explained using Figures 27A and 28. Figure 28 shows the voltages and currents at various positions in the voltage generation circuit 1. In Figure 28, the horizontal axis represents time and the vertical axis represents voltage values.

[0159] The upper graph in Figure 28 shows the input voltage Vin of the voltage generation circuit 1 with the automatic reset circuit K4 in a time series. Here, in particular, it is shown that when the power is turned on, the input voltage Vin rises, for example, from 3V to 8V. The middle graph in Figure 28 shows the voltage at point C of the voltage generation circuit 1 with the automatic reset circuit K4, the current flowing through resistor R15, and the current flowing through resistor R16 in a time series. The lower graph in Figure 28 shows the output voltage Vout of the voltage generation circuit 1 with the automatic reset circuit K4, and the voltage at the non-inverting input terminal IC1+ of the operational amplifier IC1, i.e., the voltage at point B, in a time series.

[0160] When the power supply for the voltage generation circuit 1 is turned on, the voltage at point D becomes high, as shown in Figure 28, and charge is charged to capacitor C4 via resistors R15 and R16. While current is flowing through resistor R15, transistor Q5 turns on, and the voltage at point B becomes high, causing the add-on circuit K1 to operate. In other words, the automatic reset circuit K4 makes it easier to turn on the operational amplifier IC1 of the add-on circuit K1, allowing the operational amplifier IC1 to output a high voltage.

[0161] Next, we will describe the case where the voltage generation circuit 1 has a discharge circuit. Possible discharge circuits include a microcontroller-controlled discharge circuit that discharges according to the control signal of the microcontroller, and an automatic discharge circuit that resets through the operation of the circuit without using the control signal of the microcontroller. The discharge circuit may also be included in the additional circuit K1.

[0162] The discharge circuit is a circuit that forcibly lowers the voltage at the voltage output terminal Vout, thereby creating a state where the voltage VB is higher than the voltage VA at point A, which corresponds to the voltage at the voltage output terminal Vout. As a result, even if charge is accumulated in capacitor C1, it is discharged, so voltage VA < voltage VB. Therefore, the charging circuit KA of the additional circuit K1 can be activated earlier. Specifically, after the input voltage Vin is turned off once, the discharge circuit discharges the charge accumulated in capacitor C1 and controls the voltage at the non-inverting input terminal IC1+ to be higher than the output voltage Vout.

[0163] First, we will explain the case where the voltage generation circuit 1 has a microcontroller-controlled discharge circuit K5.

[0164] The operation of the voltage generation circuit 1 when it has a microcontroller-controlled discharge circuit K5 will be explained using Figures 29A and 29B. Figure 29A is a diagram showing the configuration of the voltage generation circuit 1. In Figure 29A, components similar to those shown in other diagrams of the voltage generation circuit 1 are denoted by the same reference numerals, and their explanations are omitted or simplified. Figure 29B is a diagram showing the voltage at various positions in the voltage generation circuit 1. In Figure 29B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0165] The voltage generation circuit 1 in Figure 29A comprises the voltage generation circuit 1 in Figure 3A and a microcontroller-controlled discharge circuit K5. The microcontroller-controlled discharge circuit K5 includes resistors R18, R19, R20, transistor U2, transistor Q6, and capacitor C5.

[0166] Resistor R18 has terminals tR181 and tR182. Resistor R19 has terminals tR191 and tR192. Resistor R20 has terminals tR201 and tR202. Transistor U2 has gate terminal U2g, source terminal U2s, and drain terminal U2d. Transistor Q6 has base terminal Q6b, collector terminal Q6c, and emitter terminal Q6e. Capacitor C5 has terminals tC51 and tC52.

[0167] Terminal tR191 is electrically connected to a terminal to which a predetermined voltage, for example 3.3V, is applied. Terminal tR192 is electrically connected to the gate terminal U2g and the collector terminal Q6c. Terminal tR201 is electrically connected to terminal tC51 and the base terminal Q6b. Terminal tR202 is electrically connected to the uCOM terminal to which the microcontroller is connected. The uCOM terminal receives, for example, a discharge control signal from the microcontroller, specifically an on / off control signal for transistor Q6. Terminal tC52 is electrically connected to ground potential. The emitter terminal Q6e is electrically connected to ground potential. The drain terminal U2d is electrically connected to terminals tR32, tR12, tR21, tC11, and the voltage output terminal Vout. The source terminal U2s is electrically connected to terminal tR181. Terminal tR182 is electrically connected to ground potential.

[0168] The upper graph in Figure 29B shows the input voltage Vin of the voltage generation circuit 1 with the microcontroller-controlled discharge circuit K5 and the voltage at the uCOM terminal in time series. The voltage at the uCOM terminal reflects the on / off status of the control signal from the microcontroller. The control signal from the microcontroller may be the same signal used for switching the power switch S2 as described in other circuits, or it may be a different signal. The lower graph in Figure 29B shows the output voltage Vout of the voltage generation circuit 1 without the microcontroller-controlled discharge circuit K5 and the output voltage Vout of the voltage generation circuit 1 with the microcontroller-controlled discharge circuit K5 in time series.

[0169] Voltage generation circuit 1, which does not have a microcontroller-controlled discharge circuit K5, may take time for the voltage at the voltage output terminal Vout to drop after the power is cut off, i.e., after the input voltage Vin drops sharply, due to the charge accumulated in capacitor C1. As a result, the next time voltage generation circuit 1 is started up, it may take a long time to start up.

[0170] In response to this, the voltage generation circuit 1 can discharge the charge stored in capacitor C1 by operating the microcontroller-controlled discharge circuit K5 connected to the add-on circuit K1. As a result, the voltage generation circuit 1 with the microcontroller-controlled discharge circuit K5 can quickly set the output voltage Vout to an off voltage, for example, 0V, when the power is turned off. Note that the on / off control signal of the microcontroller may be shared with the signal that controls the on / off of the power switch S2.

[0171] Furthermore, in the case of the voltage generation circuit 1 in Figure 29A, if the active state of the microcontroller's on / off control is reversed, that is, if the voltage of the microcontroller's on / off control signal is set to High when the input power supply is disconnected, some elements of the microcontroller-controlled discharge circuit K5 may be omitted. For example, the microcontroller-controlled discharge circuit K5 may include a transistor U2 and a resistor R18, and the gate terminal U2g may be electrically directly connected to the uCOM terminal. The same effect can be obtained in this case as well.

[0172] Next, we will describe the case where the voltage generation circuit 1 has an automatic discharge circuit K6.

[0173] The case in which the voltage generation circuit 1 has an automatic discharge circuit K6 will be explained using Figures 30A and 30B. Figure 30A is a diagram showing the configuration of the voltage generation circuit 1. In Figure 30A, components similar to those in the configuration of the voltage generation circuit 1 shown in other figures are given the same reference numerals, and their explanations are omitted or simplified. Figure 30B is a diagram showing the input voltage Vin and output voltage Vout. In Figure 30B, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0174] The voltage generation circuit 1 in Figure 30A comprises the voltage generation circuit 1 in Figure 3A and an automatic discharge circuit K6. The automatic discharge circuit K6 comprises resistors R21, R22, R23, R24, transistor U3, and transistor U4.

[0175] Resistor R21 has terminals tR211 and tR212. Resistor R22 has terminals tR221 and tR222. Resistor R23 has terminals tR231 and tR232. Resistor R24 ​​has terminals tR241 and tR242. Transistor U3 has gate terminal U3g, source terminal U3s, and drain terminal U3d. Transistor U4 has gate terminal U4g, source terminal U4s, and drain terminal U4d.

[0176] Terminals tR211, tR231, and the voltage input terminal Vin are electrically connected. Terminals tR212, tR221, and the gate terminal U3g are electrically connected. Terminal tR222 is electrically connected to ground potential. Terminal tR232, source terminal U3s, and gate terminal U4g are electrically connected. Drain terminal U3d is electrically connected to ground potential. Source terminal U4s, terminals tR32, tR12, tR21, tC11, and the voltage output terminal Vout are electrically connected. Drain terminal U4d is electrically connected to ground potential.

[0177] The graph in Figure 30B shows the input voltage Vin of the voltage generation circuit 1 with the automatic discharge circuit K6, the output voltage Vout of the voltage generation circuit 1 without the automatic discharge circuit K6, and the output voltage Vout of the voltage generation circuit 1 with the automatic discharge circuit K6, in time series.

[0178] Voltage generation circuit 1, which does not have the automatic discharge circuit K6, takes time for the output voltage Vout to decrease, as shown in Figure 30B, and may take a long time to start up the next time it is activated. The mechanism for the long startup time is the same as that described for voltage generation circuit 1, which does not have the microcontroller-controlled discharge circuit K5.

[0179] In contrast, the voltage generation circuit 1 can automatically discharge the charge stored in capacitor C1 by operating the automatic discharge circuit K6 connected to the add-on circuit K1. Specifically, the voltage generation circuit 1 can automatically operate the automatic discharge circuit K6 to discharge the capacitor when the input voltage Vin falls below the voltage set by resistors R21 and R22, for example, 6.4V in Figure 30B. As a result, the voltage generation circuit 1 with the automatic discharge circuit K6 can quickly set the output voltage Vout to an off voltage, for example, 0V, when the power supply is cut off.

[0180] The case in which the voltage generation circuit 1 has an automatic discharge circuit K7 will be explained using Figures 31 and 32. Figure 31 is a diagram showing the configuration of the voltage generation circuit 1. In Figure 31, components similar to those shown in other figures of the voltage generation circuit 1 are given the same reference numerals, and their explanations are omitted or simplified. Figure 32 is a diagram showing the input voltage Vin and output voltage Vout. In Figure 32, the horizontal axis represents time, and the vertical axis represents the voltage value.

[0181] The voltage generation circuit 1 in Figure 31 comprises the voltage generation circuit 1 in Figure 3A and an automatic discharge circuit K7. The automatic discharge circuit K7 includes resistors R21, R22, R23, R24, transistors U3 and U4, capacitor C6, and diode D2. In other words, the automatic discharge circuit K7 is equipped with capacitor C6 and diode D2 in addition to the automatic discharge circuit K6 shown in Figure 30A.

[0182] Capacitor C6 has terminals tC61 and tC62. Diode D2 has cathode terminal tD21 and anode terminal tD22. Terminals tC61, cathode terminal tD21, source terminal U3s, and gate terminal U4g are electrically connected. Terminal tC62 is electrically connected to ground potential. Anode terminal tD22 and terminal tR232 are electrically connected.

[0183] The graph in Figure 32 shows the input voltage Vin of the voltage generation circuit 1, the output voltage Vout of the voltage generation circuit 1 without the automatic discharge circuit K7, and the output voltage Vout of the voltage generation circuit 1 with the automatic discharge circuit K7, in time series.

[0184] Compared to the voltage generation circuit 1 with the automatic discharge circuit K7 shown in Figure 31 and the voltage generation circuit 1 with the automatic discharge circuit K6 shown in Figure 30A, the voltage generation circuit 1 with the automatic discharge circuit K7 can keep the transistor U4 on for a certain period of time due to the action of the capacitor C6. As a result, the voltage generation circuit 1 with the automatic discharge circuit K7 can more easily fix the output voltage Vout1 to a value close to 0V, thereby improving the accuracy of output voltage Vout generation when the power supply is cut off.

[0185] <Application to bias power supply circuits> Next, we will explain the application of the voltage generation circuit 1 to the bias power supply circuit K2.

[0186] Figures 26A to 30A and 31 illustrate how various reset and discharge circuits can be provided for a voltage generation circuit 1 having a resistor divider circuit K0. Below, we will illustrate how various reset and discharge circuits can be provided for a voltage generation circuit 1 having a bias power supply circuit K2, i.e., a voltage generation circuit 1B.

[0187] Using Figure 33, we will explain the case where the voltage generation circuit 1B has a microcontroller-controlled reset circuit K3. Figure 33 shows the configuration of the voltage generation circuit 1B. In Figure 33, components similar to those in the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified.

[0188] The bias power supply circuit K2 may have the same configuration as the bias power supply circuit K2 shown in Figure 8, or it may have a different configuration. The bias power supply circuit K2 in Figure 33 has the same configuration as the bias power supply circuit K2 shown in Figure 8, with the addition of a Schottky barrier diode D3 and a resistor R25. The Schottky barrier diode D3 has a cathode terminal tD31 and an anode terminal tD32. The resistor R25 has terminals tR251 and tR252. The cathode terminal tD31 is electrically connected to terminal tR91, Noise2 point, terminal tC22, and source terminal U1s. The anode terminal tD32 is electrically connected to the ground terminal. Terminals tR251 and tR102 are electrically connected to the output terminal IC1out and the voltage output terminal Vout. Terminal tR252 is electrically connected to the inverting input terminal IC1-.

[0189] Even when the voltage generation circuit 1B has a microcontroller-controlled reset circuit K3, the same effect as when the voltage generation circuit 1 has a microcontroller-controlled reset circuit K3 can be obtained.

[0190] Similarly, the same effect can be obtained when the voltage generation circuit 1B has an automatic reset circuit K4 as when the voltage generation circuit 1 has an automatic reset circuit K4.

[0191] Next, we will describe the case where the voltage generation circuit 1B has a microcontroller-controlled discharge circuit K5.

[0192] The case where the voltage generation circuit 1B has a microcontroller-controlled discharge circuit K5 will be explained using Figure 34. Figure 34 shows the configuration of the voltage generation circuit 1B. In Figure 34, components that are the same as those in the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified.

[0193] In Figure 34, the microcontroller-controlled discharge circuit K5 is reversed compared to the microcontroller-controlled discharge circuit K5 in Figure 29A, with the positions of transistor U2 and resistor R18 reversed. Terminal tR181 is electrically connected to terminal tR41 and the voltage input terminal Vin, etc. Terminal tR182 is electrically connected to the drain terminal U2d. The source terminal U2s is electrically connected to ground potential.

[0194] Even when the voltage generation circuit 1B has a microcontroller-controlled discharge circuit K5, the same effect as when the voltage generation circuit 1 has a microcontroller-controlled discharge circuit K5 can be obtained.

[0195] Next, we will describe the case where the voltage generation circuit 1B has a microcontroller-controlled discharge circuit K5A. The microcontroller-controlled discharge circuit K5A is a modified version of the microcontroller-controlled discharge circuit K5.

[0196] The case where the voltage generation circuit 1B has a microcontroller-controlled discharge circuit K5A will be explained using Figure 35. Figure 35 is a diagram showing the configuration of the voltage generation circuit 1B. In Figure 35, components that are the same as those in the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified.

[0197] The microcontroller-controlled discharge circuit K5A in Figure 35 differs from the microcontroller-controlled discharge circuit K5 in Figure 34 in that terminal tR181 is connected to a different location. Terminal tR181 is electrically connected to the voltage output terminal Vout, terminal tR102, output terminal IC2out, inverting input terminal IC1-, etc.

[0198] The voltage generation circuit 1B having the microcontroller-controlled discharge circuit K5A shown in Figure 35 has the same effect as the voltage generation circuit 1B having the microcontroller-controlled discharge circuit K5 shown in Figure 34.

[0199] Next, we will describe the case where the voltage generation circuit 1B has an automatic discharge circuit K7A. The automatic discharge circuit K7A is a modified version of the automatic discharge circuit K7.

[0200] The case where the voltage generation circuit 1B has an automatic discharge circuit K7A will be explained using Figure 36. Figure 36 shows the configuration of the voltage generation circuit 1B. In Figure 36, components similar to those in the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified.

[0201] Compared to the automatic discharge circuit K7 in Figure 31, the automatic discharge circuit K7A in Figure 36 differs in the connections between terminals tR211, tR231, and source terminal U4s. Specifically, terminals tR211, tR231, source terminal U4s, terminal tR41, and voltage input terminal Vin are electrically connected.

[0202] Even when the voltage generation circuit 1B has an automatic discharge circuit K7A, the same effect as when the voltage generation circuit 1 has an automatic discharge circuit K7 can be obtained. Furthermore, the automatic discharge circuit K7A is not connected to the operational amplifier IC2. If the automatic discharge circuit K7A were connected to the output terminal of the operational amplifier IC2, when the charge remaining in capacitor C2 is discharged, the charge would flow to ground through the input and output terminals of the operational amplifier IC2. In other words, the input and output terminals of the operational amplifier IC2 would be short-circuited, which could place a load on the operational amplifier IC2. On the other hand, in this embodiment, since the automatic discharge circuit K7A is not connected to the operational amplifier IC2, the operational amplifier IC2 does not receive a discharge current. This reduces the load on the operational amplifier IC2.

[0203] Next, we will describe the case where the voltage generation circuit 1B has an automatic discharge circuit K7B. The automatic discharge circuit K7B is a modified version of the automatic discharge circuit K7.

[0204] The case in which the voltage generation circuit 1B has an automatic discharge circuit K7B will be explained using Figure 37. Figure 37 shows the configuration of the voltage generation circuit 1B. In Figure 37, components similar to those in the configuration of the voltage generation circuit 1 shown in other figures are denoted by the same reference numerals, and their explanations are omitted or simplified.

[0205] The automatic discharge circuit K7B in Figure 37 differs from the automatic discharge circuit K7 in Figure 31 in that the connections between terminals tR211, tR231, and source terminal U4s are different. Specifically, terminals tR211, tR231, source terminal U4s, voltage output terminal Vout, terminal tR102, output terminal IC2out, and inverting input terminal IC1- are electrically connected.

[0206] Even when the voltage generation circuit 1B has an automatic discharge circuit K7B, the same effect as when the voltage generation circuit 1 has an automatic discharge circuit K7 can be obtained.

[0207] Next, we will compare and explain the cases in which the voltage generation circuit 1B has an automatic discharge circuit K7A and the cases in which it has an automatic discharge circuit K7B.

[0208] Figure 38 shows the input voltage Vin for the cases where the voltage generation circuit 1B has an automatic discharge circuit K7A and an automatic discharge circuit K7B. Figure 39 shows the output voltage Vout for the cases where the voltage generation circuit 1B has an automatic discharge circuit K7A, an automatic discharge circuit K7B, and no automatic discharge circuit.

[0209] As shown in Figure 38, when the voltage generation circuit 1B has the automatic discharge circuit K7A shown in Figure 36, the input voltage Vin may be a negative value. Also, as shown in Figure 39, the output voltage Vout may be 0V or less.

[0210] The automatic discharge circuit K7A in Figure 36 is connected to the voltage input terminal Vin. When the voltage generation circuit 1B is equipped with the automatic discharge circuit K7A, the time it takes for the output voltage Vout to reach 0V is the fastest, as shown in Figure 39. Also, the operational amplifier IC2 is less likely to be overloaded.

[0211] The automatic discharge circuit K7B in Figure 37 is connected to the voltage output terminal Vout. When the voltage generation circuit 1B is equipped with the automatic discharge circuit K7B, the input voltage Vin and output voltage Vout are less likely to become negative. Even if the input voltage Vin and output voltage Vout do become negative, their absolute values ​​are smaller than when the voltage generation circuit 1B is equipped with the automatic discharge circuit K7A. In the example shown in Figure 39, the output voltage Vout when the voltage generation circuit 1B is equipped with the automatic discharge circuit K7B is, for example, approximately -0.04V. Also, when the voltage generation circuit 1B is equipped with the automatic discharge circuit K7B, the time it takes for the output voltage Vout to become 0V is shorter than when the discharge circuit is not equipped.

[0212] Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure. Furthermore, the components of the above embodiments may be combined in any way without departing from the spirit of the invention.

[0213] (Note) Based on the descriptions of the embodiments described above, the following technologies are disclosed.

[0214] (Technology 1) A voltage input terminal to which an input voltage is applied, A voltage output terminal from which an output voltage is output, A first resistor having a first terminal and a second terminal, wherein the first terminal is electrically connected to the voltage input terminal and the second terminal is electrically connected to the voltage output terminal, A second resistor having a third terminal and a fourth terminal, wherein the third terminal is electrically connected to the second terminal, A first capacitor electrically connected to one of the first terminal and the second terminal, A first circuit includes a charging circuit that is electrically connected to one of the first terminal and the second terminal and charges the first capacitor, A voltage generation circuit equipped with the following features.

[0215] The voltage input terminal is, for example, the voltage input terminal Vin. The voltage output terminal is, for example, the voltage output terminal Vout. The first terminal is, for example, terminal tR11 or terminal tR71. The second terminal is, for example, terminal tR12 or terminal tR72. The first resistor is, for example, resistor R1 or resistor R7. The third terminal is, for example, terminal tR21 or terminal tR81. The fourth terminal is, for example, terminal tR22 or terminal tR82. The second resistor is, for example, resistor R2 or resistor R8. The first capacitor is, for example, capacitor C1 or capacitor C2. The charging circuit is, for example, charging circuit KA. The first circuit is, for example, additional circuit K1. The voltage generation circuit is, for example, voltage generation circuit 1 or voltage generation circuit 1B.

[0216] This allows the voltage generation circuit to rapidly charge the first capacitor using the charging circuit. Therefore, even when generating the output voltage using the first capacitor, the output voltage can be stabilized quickly while reducing noise.

[0217] (Technology 2) The first circuit is, A third resistor having a fifth terminal and a sixth terminal, the fifth terminal of which is electrically connected to the voltage input terminal, A fourth resistor having a seventh terminal and an eighth terminal, wherein the seventh terminal is electrically connected to the sixth terminal, The aforementioned charging circuit is An operational amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, wherein the non-inverting input terminal is electrically connected to the sixth terminal and the inverting input terminal is electrically connected to the second terminal, A first transistor having a first control terminal, a first non-control terminal, and a second non-control terminal, wherein the first control terminal is electrically connected to the output terminal and the first non-control terminal is electrically connected to the voltage input terminal, A fifth resistor having a ninth terminal and a tenth terminal, wherein the ninth terminal is electrically connected to the second non-control terminal and the tenth terminal is electrically connected to the second terminal, Voltage generation circuit as described in Technical 1.

[0218] The fifth terminal is, for example, terminal tR41. The sixth terminal is, for example, terminal tR42. The third resistor is, for example, resistor R4. The seventh terminal is, for example, terminal tR51. The eighth terminal is, for example, terminal tR52. The fourth resistor is, for example, resistor R5. The inverting input terminal is, for example, the inverting input terminal IC1-. The non-inverting input terminal is, for example, the non-inverting input terminal IC1+. The output terminal is, for example, the output terminal IC1out. The operational amplifier is, for example, operational amplifier IC1. The first control terminal is, for example, the base terminal Q1b or the gate terminal U1b. The first non-control terminal is, for example, the collector terminal Q1c or the source terminal U1s. The third non-control terminal is, for example, the emitter terminal Q1e or the drain terminal U1d. The first transistor is, for example, transistor Q1 or transistor U1. The ninth terminal is, for example, terminal tR31. The tenth terminal is, for example, terminal tR32. The fifth resistor is, for example, resistor R3.

[0219] This allows the voltage generation circuit to raise the voltage at the non-inverting input terminal higher than the output voltage, enabling the operational amplifier to operate. Therefore, a charging current can be rapidly supplied from the voltage input terminal through the transistor and the fifth resistor, allowing the first capacitor to be rapidly charged.

[0220] (Technology 3) The aforementioned operational amplifier is The non-inverting input voltage input to the non-inverting input terminal and the inverting input voltage input to the inverting input terminal are compared, If the non-inverting input voltage is less than the inverting input voltage, an on-voltage that turns on the first transistor is output from the output terminal. If the non-inverting input voltage is greater than the inverting input voltage, an off voltage is output from the output terminal to turn off the first transistor. Voltage generation circuit as described in Technical 2.

[0221] This allows the voltage generation circuit to switch between either turning on the first transistor to charge the first capacitor, or turning off the first transistor to not charge the first capacitor.

[0222] (Technology 4) The first circuit includes a stop circuit for stopping the operation of the charging circuit. The voltage generation circuit according to any one of Technologies 1 to 3.

[0223] Thereby, the voltage generation circuit can stop the operation of the charging circuit by the stop circuit.

[0224] (Technology 5) The stop circuit has an eleventh terminal and a twelfth terminal, a sixth resistor in which the eleventh terminal is electrically connected to the sixth terminal, has a second control terminal, a third non-control terminal, and a fourth non-control terminal, and includes a second transistor in which the second control terminal is electrically connected to the output terminal and the fourth non-control terminal is electrically connected to the twelfth terminal, when the off voltage is input to the second control terminal, the second transistor becomes an on state, The voltage generation circuit according to Technology 4.

[0225] The eleventh terminal is, for example, terminal tR61. The twelfth terminal is, for example, terminal tR62. The sixth resistor is, for example, resistor R6. The second control terminal is, for example, base terminal Q2b or gate terminal U2g. The third non-control terminal is, for example, collector terminal Q2c or source terminal U2s. The fourth non-control terminal is emitter terminal Q2e or drain terminal U2d. The second transistor is, for example, transistor Q2 or transistor U2.

[0226] Thereby, when the output voltage becomes higher than the voltage of the non-inverting input terminal in the voltage generation circuit, the op-amp outputs the off voltage, so that the second transistor becomes an on state. Therefore, a state where the output voltage is higher than the voltage of the non-inverting input terminal is maintained. Thus, the voltage generation circuit can suppress the operation of the charging circuit even if there is, for example, a fluctuation in the input voltage.

[0227] (Technology 6) The first circuit comprises a diode having a cathode terminal and an anode terminal, The cathode terminal is electrically connected to the voltage input terminal. The anode terminal is electrically connected to the inverting input terminal. A voltage generation circuit as described in any one of Techniques 2 through 5.

[0228] The cathode terminal is, for example, cathode terminal tD11. The anode terminal is, for example, anode terminal tD12. The diode is, for example, Schottky barrier diode D1.

[0229] This allows the voltage generation circuit to prevent reverse current through the Schottky barrier diode D1, protecting the operational amplifier from damage even when the input voltage is rapidly turned off, i.e., to a low voltage.

[0230] (Technology 7) The first circuit includes a reset circuit, The reset circuit, after the input voltage to the voltage input terminal is turned off once, supplies a voltage to the non-inverting input terminal to make the voltage at the non-inverting input terminal higher than the output voltage. A voltage generating circuit as described in any one of the technical sections 2 to 6.

[0231] The reset circuit is, for example, a microcontroller-controlled reset circuit K3 or an automatic reset circuit K4.

[0232] As a result, the voltage generation circuit can create a state where the voltage at the non-inverting input terminal is higher than the output voltage, even if the output voltage becomes higher than the voltage at the non-inverting input terminal when the power is cut off, allowing the operational amplifier to operate and output an on voltage. Therefore, when the power is restored, the voltage generation circuit can quickly start the charging circuit, and thus quickly stabilize the output voltage.

[0233] (Technology 8) The first circuit comprises a discharge circuit, The discharge circuit discharges the charge stored in the first capacitor after the input voltage to the voltage input terminal has been turned off, thereby raising the voltage at the non-inverting input terminal higher than the output voltage. A voltage generating circuit as described in any one of the technical sections 2 to 6.

[0234] The discharge circuit is, for example, a microcontroller-controlled discharge circuit K5, an automatic discharge circuit K6, or an automatic discharge circuit K7.

[0235] As a result, the voltage generation circuit can create a state where the voltage at the non-inverting input terminal is higher than the output voltage, even if the output voltage becomes higher than the voltage at the non-inverting input terminal when the power is cut off, allowing the operational amplifier to operate and output an on voltage. Therefore, when the power is restored, the voltage generation circuit can quickly start the charging circuit, and thus quickly stabilize the output voltage.

[0236] (Technology 9) The first capacitor and the first circuit are electrically connected to the first terminal. A voltage generation circuit as described in any one of the technologies 1 through 8.

[0237] This allows the voltage generation circuit to quickly stabilize the output voltage while reducing noise, even when generating the output voltage using a first capacitor electrically connected to the first terminal. Here, for example, the first terminal is terminal tR71, and the first capacitor is capacitor C2.

[0238] (Technology 10) The first capacitor and the first circuit are electrically connected to the second terminal. A voltage generation circuit as described in any one of the technologies 1 through 8.

[0239] This allows the voltage generation circuit to quickly stabilize the output voltage while reducing noise, even when generating the output voltage using a first capacitor electrically connected to the second terminal. Here, for example, the second terminal is tR12 and the first capacitor is capacitor C1.

Industrial Applicability

[0240] The present disclosure is useful as a voltage generation circuit or the like that can quickly stabilize the output voltage while reducing noise even when generating the output voltage using a capacitor.

Explanation of Signs

[0241] 1, 1B Voltage generation circuit C1, C2 Capacitors IC1, IC2 Operational amplifiers R1, R2, R3, ··· Resistors tc11, tc12, tc21, tc22, ··· Terminals tr11, tr12, tr21, tr22, ··· Terminals Q1, Q2, ··· Transistors U1, U2, ··· Transistors K0 Resistance division circuit K1 Addition circuit K2 Bias power supply circuit K3 Microcomputer control reset circuit K4 Automatic reset circuit K5 Microcomputer control discharge circuit K6, K7 Automatic discharge circuit Vin Voltage input terminal Vout Voltage output terminal

Claims

1. A voltage input terminal to which an input voltage is applied, A voltage output terminal from which an output voltage is output, A first resistor having a first terminal and a second terminal, wherein the first terminal is electrically connected to the voltage input terminal and the second electrical terminal is electrically connected to the voltage output terminal, A second resistor having a third terminal and a fourth terminal, wherein the third terminal is electrically connected to the second terminal, A first capacitor electrically connected to one of the first terminal and the second terminal, A first circuit includes a charging circuit that is electrically connected to one of the first terminal and the second terminal and charges the first capacitor, A voltage generation circuit equipped with the following features.

2. The first circuit is, A third resistor having a fifth terminal and a sixth terminal, the fifth terminal of which is electrically connected to the voltage input terminal, A fourth resistor having a seventh terminal and an eighth terminal, wherein the seventh terminal is electrically connected to the sixth terminal, The aforementioned charging circuit is An operational amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal, wherein the non-inverting input terminal is electrically connected to the sixth terminal and the inverting input terminal is electrically connected to the second terminal, A first transistor having a first control terminal, a first non-control terminal, and a second non-control terminal, wherein the first control terminal is electrically connected to the output terminal and the first non-control terminal is electrically connected to the voltage input terminal, A fifth resistor having a ninth terminal and a tenth terminal, wherein the ninth terminal is electrically connected to the second non-control terminal and the tenth terminal is electrically connected to the second terminal, The voltage generation circuit according to claim 1.

3. The aforementioned operational amplifier is The non-inverting input voltage input to the non-inverting input terminal and the inverting input voltage input to the inverting input terminal are compared, If the non-inverting input voltage is less than the inverting input voltage, an on-voltage that turns on the first transistor is output from the output terminal. If the non-inverting input voltage is greater than the inverting input voltage, an off voltage is output from the output terminal to turn off the first transistor. The voltage generation circuit according to claim 2.

4. The first circuit includes a stop circuit for stopping the operation of the charging circuit. The voltage generation circuit according to claim 3.

5. The aforementioned stop circuit is A sixth resistor having an eleventh terminal and a twelfth terminal, wherein the eleventh terminal is electrically connected to the sixth terminal, A second transistor having a second control terminal, a third non-control terminal, and a fourth non-control terminal, wherein the second control terminal is electrically connected to the output terminal and the fourth non-control terminal is electrically connected to the twelfth terminal, When the aforementioned off voltage is input to the second control terminal, the second transistor turns on. The voltage generation circuit according to claim 4.

6. The first circuit comprises a diode having a cathode terminal and an anode terminal, The cathode terminal is electrically connected to the voltage input terminal. The anode terminal is electrically connected to the inverting input terminal. The voltage generation circuit according to claim 2.

7. The first circuit includes a reset circuit, The reset circuit, after the input voltage to the voltage input terminal is turned off once, supplies a voltage to the non-inverting input terminal to make the voltage at the non-inverting input terminal higher than the output voltage. The voltage generation circuit according to claim 2 or 3.

8. The first circuit includes a discharge circuit, The discharge circuit discharges the charge stored in the first capacitor after the input voltage to the voltage input terminal has been turned off, thereby raising the voltage at the non-inverting input terminal higher than the output voltage. The voltage generation circuit according to claim 2 or 3.

9. The first capacitor and the first circuit are electrically connected to the first terminal. The voltage generation circuit according to claim 1 or 2.

10. The first capacitor and the first circuit are electrically connected to the second terminal. The voltage generation circuit according to claim 1 or 2.

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