Electronic circuit, electronic device, and wireless communication device

Abstract

The present invention is provided with: a first switch that has a first terminal to which a power supply is connected, a second terminal, and a control input terminal, and that controls the first switch when a negative voltage exceeding a predetermined threshold voltage with respect to a power supply voltage applied to the first terminal of the first switch is applied to the control input terminal of the first switch; the first terminal of the switch and the second terminal of the switch are conducted; and a photovoltaic element that is positively connected between the power supply and the control input terminal of the first switch, and applies a negative voltage, which exceeds a threshold voltage of the first switch with respect to a power supply voltage, to the control input terminal of the first switch using photovoltaic generated by irradiation of light.

Description

Technical Field

[0001] The present invention relates to electronic circuits, electronic devices, and wireless communication devices. This application claims priority based on Japanese Patent Application No. 2022-203946 filed on December 21, 2022, and incorporates its content herein. Background Art

[0002] Conventionally, in electronic devices using a battery as a power source, to eliminate the trouble of the user inserting the battery, the battery is directly mounted on the substrate in advance or the battery is inserted in advance. For example, Patent Document 1 describes a technique for preventing the battery from being consumed due to discharge (standby power) before the user uses the electronic device. The technique described in Patent Document 1 performs power on / off control through an optical latch circuit that utilizes the photovoltaic effect generated by a light-emitting diode (LED) when irradiated with light.

[0003] The optical latch circuit described in Patent Document 1 includes a voltage sensor, a first photovoltaic element, and a feedback resistor. The voltage sensor compares a first generated voltage input from a first input terminal with a preset first threshold voltage, and outputs a setting signal from a determination output terminal when the first generated voltage exceeds the first threshold voltage. The first photovoltaic element is forward-connected between the first input terminal and the ground point, and outputs a prescribed first generated voltage to the first input terminal through the photovoltaic effect when irradiated with light. The feedback resistor is inserted between the first input terminal and the determination output terminal.

[0004] Prior Art Documents Patent Documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-161920 Summary of the Invention

[0005] Problems to be Solved by the Invention However, in the optical latch circuit described in the above Patent Document 1, the first generated voltage output by the first photovoltaic element through the photovoltaic effect when irradiated with light is input to the first input terminal of the voltage sensor and compared with the first threshold voltage by the voltage sensor. Since this first generated voltage is a positive voltage, the input circuit to the first input terminal of the voltage sensor must be configured with positive logic, and it is difficult to diversify this input circuit. Therefore, there is a problem that it is difficult to apply the power on / off control using this optical latch circuit.

[0006] The present invention has been completed in view of such a situation, and its object is to seek improvement in power supply on / off control, which utilizes the photovoltaic power generated by a photovoltaic element such as a light-emitting diode through light irradiation.

[0007] Solution for solving the problem One aspect of the present invention is an electronic circuit, which includes: a first switch having a first terminal connected to a power supply, a second terminal, and a control input terminal, and when a negative voltage exceeding a specified threshold voltage with respect to the power supply voltage applied to the first terminal of this switch is applied to the control input terminal of this switch, the first terminal and the second terminal of this switch are made conductive; and a photovoltaic element that is forward-connected between the power supply and the control input terminal of the first switch, and uses the photovoltaic power generated through light irradiation to apply a negative voltage exceeding the threshold voltage of the first switch with respect to the power supply voltage to the control input terminal of the first switch.

[0008] One aspect of the present invention is that, in the above electronic circuit, the first switch is a P-channel MOSFET, the first terminal of the first switch is the source of the P-channel MOSFET, the second terminal of the first switch is the drain of the P-channel MOSFET, and the control input terminal of the first switch is the gate of the P-channel MOSFET.

[0009] One aspect of the present invention is that, in the above electronic circuit, a pull-up resistor is further provided in parallel with the photovoltaic element between the power supply and the control input terminal of the first switch.

[0010] One aspect of the present invention is that, in the above electronic circuit, a second switch is further provided, which has a first terminal connected to the control input terminal of the first switch, a second terminal to which a negative voltage exceeding the threshold voltage of the first switch with respect to the power supply voltage is applied, and a control input terminal connected to an external control signal input from outside the electronic circuit, and makes the first terminal and the second terminal of this switch conductive according to the external control signal.

[0011] One aspect of the present invention is that, in the above electronic circuit, the second switch is an N-channel MOSFET, the first terminal of the second switch is the drain of the N-channel MOSFET, the second terminal of the second switch is the source of the N-channel MOSFET, and the control input terminal of the second switch is the gate of the N-channel MOSFET.

[0012] One aspect of the present invention is that, in the above electronic circuit, the second terminal of the second switch is grounded or a negative power supply voltage of the power supply is applied.

[0013] One embodiment of the present invention is that, in the above-mentioned electronic circuit, a third switch is further provided. The switch has a first terminal, a second terminal, and a control input terminal connected to the power supply. When a negative voltage exceeding a specified threshold voltage with respect to the power supply voltage applied to the first terminal of this switch is applied to the control input terminal of this switch, the first terminal and the second terminal of this switch are made conductive. The photovoltaic element is also connected in the forward direction between the power supply and the control input terminal of the third switch.

[0014] One embodiment of the present invention is that, in the above-mentioned electronic circuit, a voltage-dividing resistor is further provided. The voltage-dividing resistor is connected in series with the pull-up resistor between the cathode of the photovoltaic element and the control input terminal of the first switch. The relationship between the resistance values of the pull-up resistor and the voltage-dividing resistor is such that when the first terminal and the second terminal of the second switch are conductive, a negative voltage exceeding the threshold voltage of the third switch with respect to the power supply voltage is not applied to the control input terminal of the third switch.

[0015] One embodiment of the present invention is that, in the above-mentioned electronic circuit, the third switch is a P-channel MOSFET. The first terminal of the third switch is the source of the P-channel MOSFET, the second terminal of the third switch is the drain of the P-channel MOSFET, and the control input terminal of the third switch is the gate of the P-channel MOSFET.

[0016] One embodiment of the present invention is that, in the above-mentioned electronic circuit, the photovoltaic element is a red light-emitting diode or an infrared light-emitting diode.

[0017] One embodiment of the present invention is that, in the above-mentioned electronic circuit, a process of performing predetermined control is carried out by irradiating the photovoltaic element with specific pulsed light.

[0018] One embodiment of the present invention is an electronic device, which includes: the above-mentioned electronic circuit; the power supply; and a load circuit that receives the supply of power from the second terminal of the first switch.

[0019] One embodiment of the present invention is an electronic device, which includes: the above-mentioned electronic circuit; the power supply; and a control circuit that receives the supply of power from the second terminal of the first switch, and the control circuit outputs an external control signal connected to the control input terminal of the second switch.

[0020] One embodiment of the present invention is that, in the above-mentioned electronic device, when a specified time has elapsed after the control circuit is started, the control circuit outputs the external control signal.

[0021] One aspect of the present invention is a wireless communication device, which includes: a first switch having a first terminal connected to a power supply, a second terminal, and a control input terminal, and when a negative voltage exceeding a specified threshold voltage with respect to the power supply voltage applied to the first terminal of the present switch is applied to the control input terminal of the present switch, the first terminal and the second terminal of the present switch are made conductive; and a photovoltaic element that is connected in the forward direction between the power supply and the control input terminal of the first switch, and uses the photovoltaic power generated by light irradiation to apply a negative voltage exceeding the threshold voltage of the first switch with respect to the power supply voltage to the control input terminal of the first switch, and transmits radio waves by irradiating light on the photovoltaic element.

[0022] Advantages of the Invention According to the present invention, an effect of improving the power supply on / off control can be obtained, and the power supply on / off control utilizes the photovoltaic power generated by light irradiation of a photovoltaic element such as a light-emitting diode. Description of the Drawings

[0023] Figure 1 is a block diagram showing a structural example of the electronic device of the first embodiment. Figure 2 is a diagram showing a specific structural example of the electronic device of the first embodiment. Figure 3 is a flowchart showing an operation example of the electronic circuit of the first embodiment. Figure 4 is a diagram showing a specific structural example of the electronic device of the second embodiment. Figure 5 is a diagram showing a specific structural example of the electronic device 1 of the third embodiment. Figure 6 is a flowchart showing an operation example of the electronic circuit of the third embodiment. Figure 7 is a diagram showing a specific structural example of the electronic device of the fourth embodiment. Figure 8 is a diagram showing a specific structural example of the electronic device of the fourth embodiment. Detailed Embodiments

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0025] [First Embodiment] Figure 1 is a block diagram showing a structural example of the electronic device 1 of the first embodiment. In Figure 1In [the device], the electronic device 1 includes an electronic circuit 10, a power supply BT, and a load circuit 30. The electronic circuit 10 is a circuit for performing power supply on / off control, and this power supply on / off control utilizes the photovoltaic power generated by a photovoltaic element such as a light-emitting diode when irradiated with light. The electronic circuit 10 switches between on (power supply) and off (no power supply) when supplying the power supplied from the power supply BT to the load circuit 30. The load circuit 30 receives the supply of power from the power supply BT via the electronic circuit 10.

[0026] The power supply BT is, for example, a battery. In the electronic device 1 where a battery is used as the power supply BT, in order to eliminate the trouble for the user to insert the battery, the battery is directly mounted on the substrate in advance, or the battery is inserted in advance.

[0027] Figure 2 It is a diagram showing a specific structural example of the electronic device 1 of the first embodiment. Figure 2 It shows a specific circuit structural example of the electronic circuit 10.

[0028] In Figure 2 the electronic circuit 10 includes a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor) _Q1 (first switch), an N-channel MOSFET _Q2 (second switch), a light-emitting diode D1, and a pull-up resistor R1.

[0029] The light-emitting diode D1 is an example of a photovoltaic element. As the photovoltaic element, other than a light-emitting diode, for example, a photodiode or a solar cell can also be used.

[0030] The source (first terminal) of the P-channel MOSFET _Q1 is connected to the positive terminal of the power supply BT, the anode of the light-emitting diode D1, and one terminal (first terminal) of the pull-up resistor R1. The negative terminal of the power supply BT is connected to the ground terminal GND (0 volts (V)) of the electronic device 1.

[0031] The drain (second terminal) of the P-channel MOSFET _Q1 is connected to the power supply terminal POW of the control circuit 30A. The control circuit 30A is an example of the load circuit 30. The control circuit 30A operates with the power supplied to the power supply terminal POW. When power is supplied to the power supply terminal POW, the control circuit 30A starts.

[0032] The control circuit 30A is, for example, a microcomputer. The microcomputer serving as the control circuit 30A realizes the functions of the control circuit 30A by executing a prescribed program.

[0033] The gate (control input terminal) of the P-channel MOSFET_Q1 is connected to the cathode of the light-emitting diode D1, one terminal (the second terminal) of the pull-up resistor R1, and the source (the first terminal) of the N-channel MOSFET_Q2.

[0034] The light-emitting diode D1 is forward-connected between the positive terminal of the power supply BT and the gate of the P-channel MOSFET_Q1. That is, the anode of the light-emitting diode D1 is connected to the positive terminal of the power supply BT, and the cathode of the light-emitting diode D1 is connected to the gate of the P-channel MOSFET_Q1.

[0035] The pull-up resistor R1 is connected in parallel with the light-emitting diode D1 between the positive terminal of the power supply BT and the gate of the P-channel MOSFET_Q1. That is, one terminal (the first terminal) of the pull-up resistor R1 is connected to the positive terminal of the power supply BT and the anode of the light-emitting diode D1, and the other terminal (the second terminal) of the pull-up resistor R1 is connected to the gate of the P-channel MOSFET_Q1 and the cathode of the light-emitting diode D1.

[0036] The drain (the first terminal) of the N-channel MOSFET_Q2 is connected to the gate of the P-channel MOSFET_Q1, the cathode of the light-emitting diode D1, and one terminal (the second terminal) of the pull-up resistor R1.

[0037] The source (the second terminal) of the N-channel MOSFET_Q2 is connected to the ground terminal GND of the electronic device 1. Therefore, the same voltage as the negative power supply voltage (negative power supply voltage (0V)) of the power supply BT is applied to the source of the N-channel MOSFET_Q2.

[0038] The gate (control input terminal) of the N-channel MOSFET_Q2 is connected to the output terminal OUT of the control circuit 30A. The control circuit 30A outputs an external control signal FB from the output terminal OUT. Therefore, the external control signal FB output from the output terminal OUT of the control circuit 30A is input to the gate of the N-channel MOSFET_Q2. Thus, the external control signal FB is a signal for controlling the on / off of the connection between the source and the drain of the N-channel MOSFET_Q2.

[0039] The P-channel MOSFET_Q1 conducts between the source and the drain (conducting state) when a negative voltage (negative voltage) exceeding a specified threshold voltage VTH1 with respect to the positive power supply voltage (hereinafter simply referred to as the power supply voltage) of the power supply BT applied to the source is applied to the gate. On the other hand, the P-channel MOSFET_Q1 does not conduct between the source and the drain (non-conducting state) when the negative voltage applied to the gate does not exceed the threshold voltage VTH1 with respect to the power supply voltage applied to the source.

[0040] When the source and drain of the P-channel MOSFET_Q1 are in a conducting state, power is supplied from the power supply BT to the control circuit 30A. On the other hand, when the source and drain of the P-channel MOSFET_Q1 are in a non-conducting state, power is not supplied from the power supply BT to the control circuit 30A.

[0041] The N-channel MOSFET_Q2 conducts (conducting state) between the source and drain when a positive voltage (positive voltage) exceeding a specified threshold voltage VTH2 with respect to the voltage applied to the source is applied to the gate. On the other hand, the N-channel MOSFET_Q2 does not conduct (non-conducting state) between the source and drain when the positive voltage applied to the gate does not exceed the threshold voltage VTH2 with respect to the voltage applied to the source.

[0042] When the source and drain of the N-channel MOSFET_Q2 are in a conducting state, a negative supply voltage is applied to the gate of the P-channel MOSFET_Q1. The negative supply voltage is a negative voltage exceeding the threshold voltage VTH1 with respect to the supply voltage. Thus, when the source and drain of the N-channel MOSFET_Q2 are in a conducting state, the source and drain of the P-channel MOSFET_Q1 become in a conducting state.

[0043] The on / off connection between the source and drain of the N-channel MOSFET_Q2 is controlled by an external control signal FB, so that the source and drain of the P-channel MOSFET_Q1 can be made to be in a conducting state by the external control signal FB. Specifically, if the control circuit 30A outputs the external control signal FB at the level of the supply voltage (high level (H level)), the source and drain of the N-channel MOSFET_Q2 can be made to be in a conducting state, and the source and drain of the P-channel MOSFET_Q1 can be made to be in a conducting state. On the other hand, if the control circuit 30A outputs the external control signal FB at the level of the negative supply voltage of the power supply BT (low level (L level)), the source and drain of the N-channel MOSFET_Q2 can be made to be in a non-conducting state.

[0044] The light-emitting diode D1 applies a negative voltage exceeding the threshold voltage VTH1 with respect to the supply voltage to the gate of the P-channel MOSFET_Q1 by using the photovoltaic power generated by light irradiation.

[0045] When the source and drain of N-channel MOSFET_Q2 are in a non-conducting state and no light is irradiated on LED D1, no photovoltaic effect is generated on LED D1. Instead, the power supply voltage is applied to the gate of P-channel MOSFET_Q1 via pull-up resistor R1 connected in parallel with LED D1. Therefore, when the source and drain of N-channel MOSFET_Q2 are in a non-conducting state and no light is irradiated on LED D1, the threshold voltage VTH1 of P-channel MOSFET_Q1 is not satisfied. Consequently, the source and drain of P-channel MOSFET_Q1 are in a non-conducting state, and no power is supplied from power supply BT to control circuit 30A. In this case, the only current flowing from power supply BT is the leakage current generated when P-channel MOSFET_Q1 and N-channel MOSFET_Q2 are off (non-conducting), enabling a very low standby current.

[0046] When light is irradiated onto the light-emitting diode D1, a high voltage is generated at the anode relative to the cathode of the light-emitting diode D1 (generating a so-called photovoltaic effect). Consequently, when light is irradiated onto the light-emitting diode D1 while the source and drain of the N-channel MOSFET_Q2 are in a non-conductive state, a voltage lower than the power supply voltage applied to the source by the photovoltaic effect of the light-emitting diode D1 is applied to the gate of the P-channel MOSFET_Q1.

[0047] At this time, a potential difference is generated across pull-up resistor R1, causing current to flow through it. However, if the resistance of pull-up resistor R1 is set sufficiently high, the current flowing through pull-up resistor R1 can be sufficiently reduced compared to the current generated by light-emitting diode D1, making the effect of the current flowing through pull-up resistor R1 negligible. The current generated by light-emitting diode D1 is generally between tens of microamperes (μA) and hundreds of μA, so the resistance of pull-up resistor R1 is preferably set to 100 kiloohms (kΩ) or greater.

[0048] When the source and drain of N-channel MOSFET_Q2 are in a non-conducting state, the photodiode D1 generated by light irradiation applies a negative voltage to the gate of P-channel MOSFET_Q1 that exceeds the power supply voltage applied to the source, VTH1. This causes the source and drain of P-channel MOSFET_Q1 to become conductive, and power is supplied from power supply BT to control circuit 30A. At this point, if the light irradiation of LED D1 ceases, the photodiode D1 disappears, and the threshold voltage VTH1 requirement of P-channel MOSFET_Q1 is no longer met. Consequently, the source and drain of P-channel MOSFET_Q1 become non-conducting, and power is no longer supplied from power supply BT to control circuit 30A.

[0049] In Figure 2 the electronic circuit 10, the condition for the threshold voltage VTH1 of the P-channel MOSFET_Q1 is that, with respect to the power supply voltage applied to the source, the voltage applied to the gate is a negative voltage exceeding the threshold voltage VTH1. Therefore, even if the power supply voltage decreases for some reason, since the voltage applied to the gate by the photovoltaic effect through the light-emitting diode D1 is "(power supply voltage) - (voltage corresponding to the amount of photovoltaic effect)", the amount of decrease in the power supply voltage is reduced. However, since the power supply voltage applied to the source, which is the reference voltage for the condition of the threshold voltage VTH1, also decreases equally, the decrease in the power supply voltage does not affect the condition of the threshold voltage VTH1. This is the same in the case where the power supply voltage increases for some reason. Therefore, according to Figure 2 the electronic circuit 10, for fluctuations in the power supply voltage, the P-channel MOSFET_Q1 can perform stable switching operations without being affected by the fluctuations in the power supply voltage. This is an advantage of the MOSFET compared to using a general voltage detection circuit with a fixed threshold. To form a simple structure, it is also preferable to use a MOSFET to implement the voltage detection function.

[0050] According to Figure 2 the electronic circuit 10, when the external control signal FB is at the L level, the source and drain of the N-channel MOSFET_Q2 are in a non-conductive state. Therefore, the conduction between the source and drain of the P-channel MOSFET_Q1 can be switched according to the presence or absence of light irradiation on the light-emitting diode D1. Thus, when the external control signal FB is at the L level, the power supply from the power supply BT to the control circuit 30A can be switched according to the presence or absence of light irradiation on the light-emitting diode D1. In addition, the control circuit 30A is configured to make the external control signal FB become the L level when the control circuit 30A is in a non-start state.

[0051] On the other hand, when the external control signal FB is at the H level, since the source and drain of the N-channel MOSFET_Q2 are in a conductive state, the conduction between the source and drain of the P-channel MOSFET_Q1 can be fixed in the conductive state regardless of the presence or absence of light irradiation on the light-emitting diode D1.

[0052] Therefore, when the control circuit 30A is in a non-start state, by irradiating light on the light-emitting diode D1, the conduction between the source and drain of the P-channel MOSFET_Q1 becomes conductive, and the power supply from the power supply BT to the control circuit 30A starts. After the control circuit 30A starts, the external control signal FB is changed from the L level to the H level, thereby fixing the conductive state between the source and drain of the P-channel MOSFET_Q, and continuously supplying power from the power supply BT to the control circuit 30A.

[0053] Furthermore, thereafter, when no light is irradiated to the light-emitting diode D1, the control circuit 30A changes the external control signal FB from the H level to the L level, thereby switching the source and drain of the P-channel MOSFET_Q1 to a non-conducting state and stopping the power supply from the power supply BT to the control circuit 30A.

[0054] Alternatively, the control circuit 30A may change the external control signal FB from L to H after a predetermined standby time has elapsed following startup. This effectively suppresses the effects of malfunctioning power on / off control caused by noise or unintentional light exposure to the light-emitting diode D1. This point will be explained. Even if the source and drain of the P-channel MOSFET_Q1 become conductive due to noise or unintentional light exposure to the light-emitting diode D1, and power supply from the power supply BT to the control circuit 30A begins, thereby activating the control circuit 30A, the external control signal FB will not immediately change from L to H due to this standby time. It is assumed that the conductive state between the source and drain of the P-channel MOSFET_Q1 (i.e., power supply from the power supply BT to the control circuit 30A) will not persist for an extended period during periods of noise or unintentional light exposure to the light-emitting diode D1. Therefore, even if the control circuit 30A is activated during noise or unintentional light exposure to the light-emitting diode D1, the control circuit 30A cannot continue operating until a predetermined standby time has elapsed after the activation of the control circuit 30A. Consequently, the control circuit 30A cannot change the external control signal FB from the L level to the H level. Consequently, even if power supply from the power supply BT to the control circuit 30A erroneously starts due to noise or unintentional light exposure to the light-emitting diode D1, power supply from the power supply BT to the control circuit 30A will not be continued, thereby suppressing power consumption of the power supply BT.

[0055] Furthermore, the control circuit 30A can also control the external control signal FB based on its own internal state. For example, if the control circuit 30A cannot perform the specified operation after startup, the control circuit 30A maintains the external control signal FB at the L level. Consequently, if the light irradiating the light-emitting diode D1 ceases, the power supply from the power supply BT to the control circuit 30A is stopped, thereby preventing the control circuit 30A from continuing to operate while unable to perform the specified operation.

[0056] The light-emitting diode D1 can use a red light-emitting diode (red LED) or an infrared light-emitting diode (infrared LED). When a red LED or an infrared LED is used in the light-emitting diode D1, the wavelength of the light irradiated onto the light-emitting diode D1 is preferably 840 nanometers (nm) to 950 nm. This is because, regarding the infrared LED on the light irradiation side that generates light, it is easy to obtain an LED with a large output, so it is easy to generate infrared rays strong enough.

[0057] By using an infrared LED with a large output to generate infrared rays strong enough and irradiating them onto the light-emitting diode D1 (red LED or infrared LED), even if there is a certain distance between the infrared LED on the light irradiation side and the light-emitting diode D1, the photovoltaic effect of the light-emitting diode D1 can be sufficiently generated. Moreover, even such strong infrared rays are invisible light, so it will not bring a sense of disharmony to the user. In addition, by using strong infrared rays, the photovoltaic effect of the light-emitting diode D1 can be sufficiently generated, so the effect of preventing malfunction caused by noise can be obtained.

[0058] In addition, when the power supply BT is, for example, a silver oxide battery (nominal voltage: 1.55 V) or an air zinc battery (nominal voltage: 1.4 V), the threshold voltage VTH1 of the P-channel MOSFET_Q1 and the threshold voltage VTH2 of the N-channel MOSFET_Q2 are preferably about 0.5 V to 1.3 V.

[0059] As Figure 2 a specific example of the electronic circuit 10, the power supply BT is a silver oxide battery (power supply voltage: 1.55 V), the resistance value of the pull-up resistor R1 is 1 megohm (MΩ), the light-emitting diode D1 is a red LED (VF: 1.85 V), the threshold voltage VTH1 of the P-channel MOSFET_Q1 is 0.9 V (maximum value), and the threshold voltage VTH2 of the N-channel MOSFET_Q2 is 0.9 V (maximum value).

[0060] Next, with reference to Figure 3 to describe Figure 2 the operation of the electronic circuit 10. Figure 3 is a flowchart showing an operation example of the electronic circuit 10 according to the first embodiment.

[0061] Hereinafter, the conduction between the source and drain of P-channel MOSFET_Q1 may be referred to as "P-channel MOSFET_Q1 is turned on," the conduction between the source and drain of P-channel MOSFET_Q1 may be referred to as "P-channel MOSFET_Q1 is on," the non-conduction between the source and drain of P-channel MOSFET_Q1 may be referred to as "P-channel MOSFET_Q1 is off," and the non-conduction between the source and drain of P-channel MOSFET_Q1 may be referred to as "P-channel MOSFET_Q1 is off." The same description may be used for N-channel MOSFET_Q2.

[0062] The voltage applied to the source of the P-channel MOSFET_Q1 is sometimes referred to as the source voltage, and the voltage applied to the gate of the P-channel MOSFET_Q1 is sometimes referred to as the gate voltage. The same description is sometimes used for the N-channel MOSFET_Q2.

[0063] In the initial state, in the electronic circuit 10, since the P-channel MOSFET_Q1 is off and the external control signal FB is at L level, the N-channel MOSFET_Q2 is off. Therefore, in the initial state, no power is supplied from the power supply BT to the control circuit 30A.

[0064] (Step S1) In an initial state, the P-channel type MOSFET_Q1 and the N-channel type MOSFET_Q2 are turned off.

[0065] (Step S2) If the gate voltage of P-channel MOSFET_Q1 becomes a negative voltage exceeding threshold voltage VTH1 relative to the source voltage due to irradiation of light to light diode D1 (if the threshold voltage VTH1 condition is satisfied, the determination result of step S2 is "Yes"), the process proceeds to step S3. On the other hand, if the threshold voltage VTH1 condition is not satisfied (the determination result of step S2 is "No"), the process returns to step S1.

[0066] (Step S3) Since the threshold voltage VTH1 condition is satisfied, the P-channel MOSFET_Q1 is turned on. This starts the supply of power from the power supply BT to the control circuit 30A. The control circuit 30A is activated by the power supply from the power supply BT.

[0067] (Step S4) If the control circuit 30A outputs the external control signal FB at an H level after startup ("Yes" in step S4), the process proceeds to step S5. On the other hand, if the external control signal FB output from the control circuit 30A is at an L level ("No" in step S4), the process proceeds to step S7.

[0068] (Step S5) Since the external control signal FB is at the H level, the N-channel MOSFET_Q2 is turned on.

[0069] (Step S6) When the N-channel MOSFET_Q2 is turned on, the condition of the threshold voltage VTH1 is satisfied. Therefore, the P-channel MOSFET_Q1 remains turned on. When the external control signal FB is at the H level, since the N-channel MOSFET_Q2 is turned on, the P-channel MOSFET_Q1 is turned on regardless of whether the light emitting diode D1 is irradiated with light or not. Therefore, when the external control signal FB is at the H level, power is supplied from the power supply BT to the control circuit 30A regardless of whether the light emitting diode D1 is irradiated with light or not.

[0070] (Step S7) Since the external control signal FB is at the L level, the N-channel MOSFET_Q2 is turned off. For example, after the control circuit 30A is started, the external control signal FB is changed to the H level, and then, when a specified power supply stop condition is satisfied, the control circuit 30A switches the external control signal FB from the H level to the L level. As a result, the N-channel MOSFET_Q2 is switched from on to off. At this time, if the light emitting diode D1 is not irradiated with light, the P-channel MOSFET_Q1 is switched from on to off. Therefore, the power supply from the power supply BT to the control circuit 30A is stopped. After step S7, the process returns to step S2.

[0071] According to the electronic circuit 10 of the first embodiment described above, since the input circuit to the gate of the P-channel MOSFET_Q1 can be configured with negative logic, which is a circuit for switching the presence or absence of power supply from the power supply BT to the control circuit 30A, diversification of this input circuit (such as logical OR control based on multiple open collector signals, etc.) is easy. As a result, an effect of improving the power supply on / off control can be obtained, and this power supply on / off control utilizes the photovoltaic power generated by a photovoltaic element such as a light emitting diode when irradiated with light.

[0072] [Second Embodiment] The second embodiment is a modification of the first embodiment described above. Figure 4 FIG. shows a specific structural example of the electronic device 1 of the second embodiment. Figure 4 FIG. shows a specific circuit structural example of the electronic circuit 10A of the second embodiment. In Figure 4 thereof, parts corresponding to those of Figure 2 are denoted by the same reference numerals, and their description is omitted.

[0073] In Figure 4 the electronic circuit 10A, compared with the above Figure 2The difference of the electronic circuit 10 is that instead of Figure 2 The electronic circuit 10 has a P-channel MOSFET_Q1, and uses a switch IC (Integrated Circuit) _SW. In addition to this, Figure 4 The electronic circuit 10A and Figure 2 The electronic circuit 10 is the same.

[0074] The switch IC_SW includes an input terminal IN, an output terminal OUT, and a control input terminal CTL. When the voltage applied to the control input terminal CTL is at an L level, the switch IC_SW establishes conduction between the input terminal IN and the output terminal OUT (conducting state). On the other hand, when the voltage applied to the control input terminal CTL is at an H level, the switch IC_SW establishes non-conducting state between the input terminal IN and the output terminal OUT (non-conducting state).

[0075] exist Figure 4 The electronic circuit 10A is also the same as the above Figure 2 Similarly, in electronic circuit 10, when external control signal FB is at an L level, the source and drain of N-channel MOSFET_Q2 are in a non-conductive state. Therefore, the conduction between input terminal IN and output terminal OUT of switch IC_SW can be switched depending on whether light is irradiating light-emitting diode D1. Therefore, when external control signal FB is at an L level, the supply of power from power supply BT to control circuit 30A can be switched depending on whether light is irradiating light-emitting diode D1. Furthermore, control circuit 30A is configured so that external control signal FB is at an L level when control circuit 30A is in an inactive state.

[0076] Furthermore, when the external control signal FB is at an H level, the source and drain of the N-channel MOSFET_Q2 are in a conductive state. Therefore, regardless of whether the light emitting diode D1 is irradiated with light, the conductive state between the input terminal IN and the output terminal OUT of the switch IC_SW can be fixed. Therefore, when the external control signal FB is at an H level, power can be continuously supplied from the power supply BT to the control circuit 30A, regardless of whether the light emitting diode D1 is irradiated with light.

[0077] In the second embodiment, as in the first embodiment, it is possible to improve power on / off control using photovoltaics generated by irradiation of light by photovoltaic elements such as light emitting diodes.

[0078] [Third embodiment] Figure 5 It is a diagram showing a specific configuration example of the electronic device 1 according to the third embodiment.Figure 5 Fig. 1 shows a specific circuit structure example of the electronic circuit 10B of the third embodiment. In Figure 5 , for the parts corresponding to the respective parts of Figure 2 , the same reference signs are given and their descriptions are omitted.

[0079] In Figure 5 's electronic circuit 10B, the difference from the above-mentioned Figure 2 's electronic circuit 10 is that a P-channel MOSFET_Q3 (third switch) and a voltage dividing resistor R2 are further added to Figure 2 's electronic circuit 10.

[0080] The source (first terminal) of the P-channel MOSFET_Q3 is connected to the positive terminal of the power supply BT, the anode of the light-emitting diode D1, one terminal (first terminal) of the pull-up resistor R1, and the source of the P-channel MOSFET_Q1. Therefore, the light-emitting diode D1 is forward-connected between the positive terminal of the power supply BT and the gate of the P-channel MOSFET_Q1, and is also forward-connected between the positive terminal of the power supply BT and the gate of the P-channel MOSFET_Q3.

[0081] When a negative voltage exceeding a specified threshold voltage VTH3 with respect to the power supply voltage applied to the source is applied to the gate of the P-channel MOSFET_Q3, the source and the drain are made conductive (conducting state). On the other hand, when the negative voltage applied to the gate does not exceed the threshold voltage VTH3 with respect to the power supply voltage applied to the source, the source and the drain are made non-conductive (non-conducting state).

[0082] When the source and the drain of the P-channel MOSFET_Q3 are in the conducting state, the power supply voltage is output to the output terminal OUTPUT. On the other hand, when the source and the drain of the P-channel MOSFET_Q3 are in the non-conducting state, the power supply voltage is not output to the output terminal OUTPUT.

[0083] Hereinafter, sometimes changing the source-drain interval of the P-channel MOSFET_Q3 to the conducting state is referred to as turning on the P-channel MOSFET_Q3, the source-drain interval of the P-channel MOSFET_Q3 being in the conducting state is referred to as the P-channel MOSFET_Q3 being on, changing the source-drain interval of the P-channel MOSFET_Q3 to the non-conducting state is referred to as turning off the P-channel MOSFET_Q3, and the source-drain interval of the P-channel MOSFET_Q3 being in the non-conducting state is referred to as the P-channel MOSFET_Q3 being off.

[0084] In addition, the voltage applied to the source of the P-channel MOSFET_Q3 may be referred to as a source voltage, and the voltage applied to the gate of the P-channel MOSFET_Q3 may be referred to as a gate voltage.

[0085] The voltage dividing resistor R2 is connected in series with the pull-up resistor R1 between the cathode of the light emitting diode D1 and the gate of the P-channel MOSFET_Q1.

[0086] exist Figure 5 In the electronic circuit 10B, even if the N-channel MOSFET_Q2 is turned on via the voltage divider resistor R2, its influence does not affect the P-channel MOSFET_Q3. This point will be described below.

[0087] In the initial state, in electronic circuit 10B, P-channel MOSFETs Q1 and Q3 are off, and external control signal FB is at an L level, so N-channel MOSFET Q2 is off. At this time, if light is irradiated onto light-emitting diode D1, the gate voltage of P-channel MOSFET Q1 decreases due to the photovoltaic effect generated by light-emitting diode D1.

[0088] Here, a small voltage drop occurs across voltage divider resistor R2 between the cathode of light-emitting diode D1 and the gate of P-channel MOSFET_Q1. However, this voltage drop is very small because the current flowing through voltage divider resistor R2 is only leakage current flowing between the gate of P-channel MOSFET_Q1 or the source and drain of N-channel MOSFET_Q2. Therefore, if light-emitting diode D1 generates a voltage sufficiently higher than the threshold voltage VTH1 of P-channel MOSFET_Q1, P-channel MOSFET_Q1 turns on.

[0089] Therefore, when the external control signal FB is at an L level, the P-channel MOSFET_Q1 can be switched on and off depending on whether or not light is irradiating the light-emitting diode D1. When the P-channel MOSFET_Q1 is on, power is supplied from the power supply BT to the control circuit 30A. On the other hand, when the P-channel MOSFET_Q1 is off, power is not supplied from the power supply BT to the control circuit 30A.

[0090] Next, when the external control signal FB goes high, N-channel MOSFET_Q2 turns on, thereby applying a negative power supply voltage to the gate of P-channel MOSFET_Q1. A negative power supply voltage is a voltage that exceeds threshold voltage VTH1 relative to the power supply voltage. Therefore, since the threshold voltage VTH1 condition is satisfied, P-channel MOSFET_Q1 remains on while the external control signal FB is high, regardless of whether light is irradiating light to light-emitting diode D1.

[0091] At this time, even if the external control signal FB becomes high level and the N-channel MOSFET_Q2 is turned on, thereby reducing the gate voltage of the P-channel MOSFET_Q1, due to the presence of the voltage-dividing resistor R2, the gate voltage of the P-channel MOSFET_Q3 also remains substantially the same as the power supply voltage. The gate voltage of this P-channel MOSFET_Q3 is determined by the resistance value ratio (voltage division ratio) of the pull-up resistor R1 and the voltage-dividing resistor R2. The relationship (voltage division ratio) between the resistance values of the pull-up resistor R1 and the voltage-dividing resistor R2 is such that when the N-channel MOSFET_Q2 is on, a negative voltage exceeding the threshold voltage VTH3 of the P-channel MOSFET_Q3 with respect to the power supply voltage is not applied to the gate of the P-channel MOSFET_Q3.

[0092] For example, when the resistance value of the pull-up resistor R1 is 1 MΩ and the resistance value of the voltage-dividing resistor R2 is 10 MΩ, the gate voltage of the P-channel MOSFET_Q3 is a voltage of 10 / 11 of the power supply voltage (a voltage approximately 0.91 times the power supply voltage). As a specific example, since the threshold voltage VTH3 of the P-channel MOSFET_Q3 is "0.9 V (maximum value)" and the power supply voltage of the silver oxide battery as the power supply BT is "1.55 V", this gate voltage "0.91×1.55 = 1.41" does not satisfy the condition of the threshold voltage VTH3 for the P-channel MOSFET_Q3 to turn on. Thus, when the external control signal FB is high level, the P-channel MOSFET_Q3 is off when there is no light irradiation on the light-emitting diode D1, and on the other hand, when there is light irradiation on the light-emitting diode D1, it turns on by the photovoltaic effect of the light-emitting diode D1 and satisfies the condition of the threshold voltage VTH3.

[0093] Therefore, when the external control signal FB is high level, the P-channel MOSFET_Q1 remains on regardless of the presence or absence of light irradiation on the light-emitting diode D1. On the other hand, for the P-channel MOSFET_Q3, it can be switched between on and off according to the presence or absence of light irradiation on the light-emitting diode D1. When the P-channel MOSFET_Q3 is on, the power supply voltage is output to the output terminal OUTPUT. On the other hand, when the P-channel MOSFET_Q3 is off, the power supply voltage is not output to the output terminal OUTPUT.

[0094] As described above, according to Figure 5The electronic circuit 10B realizes a switching function of turning on and off the P-channel MOSFET_Q1 according to the presence or absence of light irradiation on the light-emitting diode D1 when the external control signal FB is at the L level. Through this switching function, it is possible to switch the on / off state of the power supply from the power supply BT to the control circuit 30A according to the presence or absence of light irradiation on the light-emitting diode D1.

[0095] On the other hand, when the external control signal FB is at the H level, it realizes a switching function of turning on and off the P-channel MOSFET_Q3 according to the presence or absence of light irradiation on the light-emitting diode D1 while keeping the P-channel MOSFET_Q1 on. Through this switching function, it is possible to switch the output to the output terminal OUTPUT according to the presence or absence of light irradiation on the light-emitting diode D1.

[0096] As described above, according to Figure 5 the electronic circuit 10B, it is possible to realize the switching function of the P-channel MOSFET_Q1 and the switching function of the P-channel MOSFET_Q3 respectively through one light-emitting diode D1.

[0097] Here, an example of the usage method of the output terminal OUTPUT is given.

[0098] (Example 1 of the usage method of the output terminal OUTPUT) By connecting the output terminal OUTPUT to a control circuit 30A such as a microcomputer, the control circuit 30A can detect the presence or absence of light irradiation on the light-emitting diode D1. Thus, it is possible to control whether the control circuit 30A performs a specified process according to the presence or absence of light irradiation on the light-emitting diode D1.

[0099] (Example 2 of the usage method of the output terminal OUTPUT) Apply the electronic device 1 to a wireless communication device. The wireless communication device can detect the presence or absence of light irradiation on the light-emitting diode D1 through the output terminal OUTPUT. Thus, it is possible to control whether the wireless communication device performs a specified process according to the presence or absence of light irradiation on the light-emitting diode D1. For example, it is possible to control whether the wireless communication device transmits radio waves according to the presence or absence of light irradiation on the light-emitting diode D1.

[0100] (Example 3 of the usage method of the output terminal OUTPUT) Pulsed light (pulse light) is used as the light irradiated on the light-emitting diode D1. According to the electronic circuit 10B, even if the light irradiated on the light-emitting diode D1 is pulsed light, the output of the output terminal OUTPUT can follow the pulsed light with a sufficient response speed. Thus, by irradiating the light-emitting diode D1 with, for example, intensity-modulated pulsed light, an optical communication function of transmitting information such as a specified command or identifier (ID) to a specified device via the output terminal OUTPUT can be achieved. For example, an example of utilization is to provide a command for performing a test at the time of factory shipment of the electronic device 1 by irradiating the light-emitting diode D1 with pulsed light intensity-modulated using a specific modulation signal.

[0101] The above is an explanation of an example of the utilization method of the output terminal OUTPUT.

[0102] In addition, when the power supply BT is, for example, a silver oxide battery or an air zinc battery, the threshold voltage VTH1 of the P-channel MOSFET_Q1, the threshold voltage VTH2 of the N-channel MOSFET_Q2, and the threshold voltage VTH3 of the P-channel MOSFET_Q3 are preferably about 0.5V to 1.3V.

[0103] As Figure 5 a specific example of the electronic circuit 10B, the power supply BT is a silver oxide battery (power supply voltage is 1.55V), the resistance value of the pull-up resistor R1 is 1MΩ, the resistance value of the voltage-dividing resistor R2 is 10MΩ, the light-emitting diode D1 is a red LED (VF is 1.85V), the threshold voltage VTH1 of the P-channel MOSFET_Q1 is 0.9V (maximum value), the threshold voltage VTH2 of the N-channel MOSFET_Q2 is 0.9V (maximum), and the threshold voltage VTH3 of the P-channel MOSFET_Q3 is 0.9V (maximum value). In addition, the threshold voltages VTH1, VTH2, and VTH3 may also be different. For example, the threshold voltage VTH3 of the P-channel MOSFET_Q3 may be lower than the threshold voltage VTH1 of the P-channel MOSFET_Q1. When the threshold voltage VTH3 is lower than the threshold voltage VTH1, since the amount of voltage drop caused by the voltage-dividing resistor R2 can be eliminated, the P-channel MOSFET_Q3 can be turned on even when the irradiation of the light on the light-emitting diode D1 is weak.

[0104] Next, with reference to Figure 6 to explain Figure 5 the operation of the electronic circuit 10B. Figure 6 is a flowchart showing an operation example of the electronic circuit 10B of the third embodiment.

[0105] In the initial state, in the electronic circuit 10B, since the P-channel MOSFETs Q1 and Q3 are off and the external control signal FB is at the L level, the N-channel MOSFET Q2 is off. Therefore, in the initial state, there is no power supply from the power supply BT to the control circuit 30A. In addition, the output of the output terminal OUTPUT is at the L level when the P-channel MOSFET Q3 is off, and is at the H level when the P-channel MOSFET Q3 is on.

[0106] Here, the operation of the P-channel MOSFET Q3 will be mainly described. The operations of the P-channel MOSFET Q1 and the N-channel MOSFET Q2 are the same as those in the first embodiment according to the Figure 3 flowchart.

[0107] (Step S11) In the initial state, the P-channel MOSFET Q3 is off.

[0108] (Step S12) When the external control signal FB is output at the H level after the control circuit 30A is started (Yes in Step S12), go to Step S13. On the other hand, when the external control signal FB output from the control circuit 30A is at the L level (No in Step S12), go to Step S16.

[0109] (Step S13) Since the external control signal FB is at the H level, the N-channel MOSFET Q2 turns on. Here, although the N-channel MOSFET Q2 turns on, the gate voltage of the P-channel MOSFET Q3 remains almost the same as the power supply voltage, so the P-channel MOSFET Q3 is off.

[0110] (Step S14) When the gate voltage of the P-channel MOSFET Q3 with respect to the source voltage is a negative voltage exceeding the threshold voltage VTH3 by irradiating the light-emitting diode D1 (when the condition of the threshold voltage VTH3 is satisfied, Yes in the determination result of Step S14), go to Step S15. On the other hand, when the condition of the threshold voltage VTH3 is not satisfied (No in the determination result of Step S14), return to Step S11.

[0111] (Step S15) Since the condition of the threshold voltage VTH3 is satisfied, the P-channel MOSFET Q3 turns on. As a result, the output of the output terminal OUTPUT changes from the L level to the H level. Then, return to Step S12.

[0112] (Step S16) Since the external control signal FB is at the L level, the N-channel MOSFET Q2 is off. Then, return to Step S11.

[0113] As described above, according to the third embodiment, it is possible to improve the power supply on / off control that utilizes the photovoltaic power generation generated by a photovoltaic element such as a light-emitting diode through light irradiation. Furthermore, through this light irradiation, it is possible to achieve other controls other than the power supply on / off control using the P-channel MOSFET_Q3.

[0114] [Fourth Embodiment] Figure 7 FIG. is a diagram showing a specific structural example of the electronic device 1 according to the fourth embodiment. Figure 7 FIG. shows a specific circuit structural example of the electronic circuit 10C according to the fourth embodiment. In Figure 7 it, parts corresponding to the respective parts of Figure 2 are denoted by the same reference numerals, and the description thereof is omitted.

[0115] In Figure 7 the electronic circuit 10C, the difference from the above-mentioned Figure 2 electronic circuit 10 is that the N-channel MOSFET_Q2 and the pull-up resistor R1 are deleted from Figure 2 the electronic circuit 10.

[0116] The output signals of n (n is an integer of 1 or more) input circuits 50-1 to n are connected to the gate of the P-channel MOSFET_Q1. These input circuits 50-1 to n are configured with negative logic. The input circuits 50-1 to n can be any circuit structure in which the output signal becomes the L level when supplying power from the power supply BT to the load circuit 30. By connecting the output signals of the input circuits 50-1 to n to the gate of the P-channel MOSFET_Q1, it is possible to control the P-channel MOSFET_Q1 by logical OR. That is, if the gate of the P-channel MOSFET_Q1 becomes the L level, the P-channel MOSFET_Q1 is turned on, so if any one of the output signals of the input circuits 50-1 to n becomes the L level, the P-channel MOSFET_Q1 is turned on.

[0117] According to Figure 7 the electronic circuit 10C, when all the output signals of the input circuits 50-1 to n are at the H level, it is possible to switch the on / off state of the P-channel MOSFET_Q1 according to the presence or absence of light irradiation on the light-emitting diode D1. On the other hand, if any one of the output signals of the input circuits 50-1 to n becomes the L level, the P-channel MOSFET_Q1 can be turned on regardless of the presence or absence of light irradiation on the light-emitting diode D1. Therefore, according to Figure 7The electronic circuit 10C can switch the power supply from the power supply BT to the load circuit 30 according to whether the light emitting diode D1 is irradiated with light, or switch the power supply from the power supply BT to the load circuit 30 according to the output signal of the input circuit 50-1~n.

[0118] In addition, if Figure 8 The electronic circuit 10D is shown in Figure 7 In the electronic circuit 10C, a pull-up resistor R1 may be further provided. Figure 8 The electronic circuit 10D also has Figure 7 Similarly, the electronic circuit 10C can switch the power supply from the power supply BT to the load circuit 30 according to whether the light irradiates the light emitting diode D1, or switch the power supply from the power supply BT to the load circuit 30 through the output signal of the input circuit 50-1~n.

[0119] In addition, Figure 7 and Figure 8 Although input circuits 50-1 to 50-n are provided, it is also possible to omit input circuits 50-1 to 50-n and switch the P-channel MOSFET_Q1 on and off based solely on whether or not the light irradiates the light-emitting diode D1. In this way, the power supply from the power supply BT to the load circuit 30 can be switched based solely on whether or not the light irradiates the light-emitting diode D1.

[0120] The above-described embodiments can be applied in various ways. For example, by applying the electronic device 1 to a sealed device used in liquid, the device can be activated contactlessly by irradiating light to the light-emitting diode D1. Examples of such devices include equipment used in water quality surveys and small cameras. Examples of liquids include water, electrolytes, and body fluids.

[0121] While the embodiments have been used to describe the methods for implementing the present invention, the present invention is not limited to these embodiments and various modifications and substitutions can be made without departing from the spirit of the present invention. The structures described in the above embodiments and examples may also be combined.

[0122] Description of Reference Signs 1...electronic device, 10, 10A, 10B, 10C, 10D...electronic circuit, BT...power supply, 30...load circuit, Q1, Q3...P-channel MOSFET, Q2...N-channel MOSFET, D1...light-emitting diode, R1...pull-up resistor, R2...voltage divider resistor, SW...switch IC, 30A...control circuit.

Claims

1. An electronic circuit, wherein, Comprising: A first switch having a first terminal connected to a power supply, a second terminal, and a control input terminal. When a negative voltage exceeding a specified threshold voltage with respect to the power supply voltage applied to the first terminal of this switch is applied to the control input terminal of this switch, the first terminal and the second terminal of this switch are made conductive; and A photovoltaic element that is forward-connected between the power supply and the control input terminal of the first switch, and uses the photovoltaic effect generated by light irradiation to apply a negative voltage exceeding the threshold voltage of the first switch with respect to the power supply voltage to the control input terminal of the first switch.

2. The electronic circuit according to claim 1, wherein The first switch is a P-channel MOSFET, The first terminal of the first switch is the source of the P-channel MOSFET, The second terminal of the first switch is the drain of the P-channel MOSFET, The control input terminal of the first switch is the gate of the P-channel MOSFET.

3. The electronic circuit according to claim 1 , wherein: It further comprises a pull-up resistor connected in parallel with the photovoltaic element between the power supply and the control input terminal of the first switch.

4. The electronic circuit according to claim 3, wherein, It further comprises a second switch having a first terminal connected to the control input terminal of the first switch, a second terminal to which a negative voltage exceeding the threshold voltage of the first switch with respect to the power supply voltage is applied, and a control input terminal connected to an external control signal input from outside the electronic circuit. When the external control signal is received, the first terminal and the second terminal of this switch are made conductive.

5. The electronic circuit according to claim 4, wherein The second switch is an N-channel MOSFET, The first terminal of the second switch is the drain of the N-channel MOSFET, The second terminal of the second switch is the source of the N-channel MOSFET, The control input terminal of the second switch is the gate of the N-channel MOSFET.

6. The electronic circuit according to claim 5, wherein, The second terminal of the second switch is grounded or a negative power supply voltage of the power supply is applied.

7. The electronic circuit according to claim 6, wherein It further comprises a third switch having a first terminal connected to the power supply, a second terminal, and a control input terminal. When a negative voltage exceeding a specified threshold voltage with respect to the power supply voltage applied to the first terminal of this switch is applied to the control input terminal of this switch, the first terminal and the second terminal of this switch are made conductive, The photovoltaic element is also forward-connected between the power supply and the control input terminal of the third switch.

8. The electronic circuit according to claim 7, wherein, It further comprises a voltage-dividing resistor connected in series with the pull-up resistor between the cathode of the photovoltaic element and the control input terminal of the first switch, The relationship between the resistance values of the pull-up resistor and the voltage-dividing resistor is such that when the first terminal and the second terminal of the second switch are conductive, a negative voltage exceeding the threshold voltage of the third switch with respect to the power supply voltage is not applied to the control input terminal of the third switch.

9. The electronic circuit according to claim 8, wherein The third switch is a P-channel MOSFET, The first terminal of the third switch is the source of the P-channel MOSFET, The second terminal of the third switch is the drain of a P-channel MOSFET. The control input terminal of the third switch is the gate of a P-channel MOSFET.

10. The electronic circuit according to claim 1, wherein The photovoltaic element is a red light-emitting diode or an infrared light-emitting diode.

11. The electronic circuit according to claim 1, wherein, A process of performing predetermined control by irradiating the photovoltaic element with specific pulsed light.

12. An electronic device, wherein, Comprising: The electronic circuit according to claim 1; The power supply; and A load circuit that receives the supply of power from the power supply at the second terminal of the first switch.

13. An electronic device, wherein, Comprising: The electronic circuit according to claim 4; The power supply; and A control circuit that receives the supply of power from the power supply at the second terminal of the first switch, The control circuit outputs an external control signal connected to the control input terminal of the second switch.

14. The electronic device according to claim 13, wherein, When a predetermined time has elapsed after the control circuit is started, the control circuit outputs the external control signal.

15. A wireless communication device, wherein, Comprising: A first switch having a first terminal connected to a power supply, a second terminal, and a control input terminal, and when a negative voltage exceeding a predetermined threshold voltage with respect to the power supply voltage applied to the first terminal of this switch is applied to the control input terminal of this switch, the first terminal and the second terminal of this switch are made conductive; and A photovoltaic element that is forward-connected between the power supply and the control input terminal of the first switch, and uses the photovoltaic effect generated by light irradiation to apply a negative voltage exceeding the threshold voltage of the first switch with respect to the power supply voltage to the control input terminal of the first switch, Transmitting an electric wave by irradiating the photovoltaic element with light.

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