Semiconductor relay device

Abstract

An embodiment provides a semiconductor relay device, which is composed of an input side and an output side that are insulated and separated, and can protect the equipment on the output side from overheating even if the output side does not include a constant current source. The semiconductor relay device of the embodiment includes a conversion circuit unit, a Zener diode, n diodes connected in series, a thyristor, and a transistor. The conversion circuit unit allows a first current to flow through a first node based on an input signal. The Zener diode has an anode connected to a second node and a cathode connected to a first node. The anode of a diode at the first end of the n diodes is connected to the first node, and the cathode of a diode at the second end of the n diodes is connected to a third node. The thyristor includes a cathode connected to the first node, an anode connected to the second node, and a control terminal connected to the third node. The transistor has a gate connected to the first node.

Description

[0001] Related Application

[0002] This application claims the priority of Japanese Patent Application No. 2021-48949 (filing date: March 23, 2021) as a basic application. The present application incorporates all the contents of the basic application by reference. Technical Field

[0003] Embodiments generally relate to a semiconductor relay device. Background Art

[0004] A semiconductor relay device is known that opens and closes the circuit of a device connected to an output terminal according to an input signal. According to the semiconductor relay device, the opening and closing of the circuit is controlled by using a device (component) of a semiconductor. This semiconductor relay device can receive input signals in a non-contact manner such as magnetism, capacitance, and light. Generally, this semiconductor relay device needs to have a mechanism to protect the device on the output side from the influence caused by applying an excessive voltage, flowing an excessive current, and overheating. Summary of the invention

[0005] An embodiment provides a semiconductor relay device that includes an input side (primary side) and an output side (secondary side) that are isolated from each other and can protect the semiconductor relay device itself and equipment on the output side from overheating even if the secondary side does not include an external power supply.

[0006] A semiconductor relay device of one embodiment includes a conversion circuit unit, a Zener diode, n diodes, a thyristor, and a transistor. The conversion circuit unit receives an input signal from the outside and causes a first current to flow through a first node based on the input signal. The Zener diode has an anode connected to the second node and a cathode connected to the first node. The n diodes are connected in series, the anode of a diode at the first end of the n diodes is connected to the first node, and the cathode of a diode at the second end of the n diodes is connected to a third node. The thyristor includes an anode connected to the first node, a cathode connected to the second node, and a control terminal connected to the third node. The transistor has a gate connected to the first node. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Functional blocks of the system of the first embodiment are shown.

[0008] Figure 2 The circuit configuration and functional blocks of the semiconductor relay device of the first embodiment in the case of the first coupling type are shown.

[0009] Figure 3The circuit configuration and functional blocks of the second coupling type semiconductor relay device according to the first embodiment are shown.

[0010] Figure 4 A circuit configuration in the case of the third coupling type of the semiconductor relay device according to the first embodiment is shown.

[0011] Figure 5 The diode set terminal voltage at different temperatures of the first embodiment is shown.

[0012] Figure 6 The relationship between the number of diodes in the semiconductor relay device of the first embodiment and the temperature of the semiconductor relay device is shown.

[0013] Figure 7 One state during operation of the semiconductor relay device of the first embodiment is shown.

[0014] Figure 8 One state during operation of the semiconductor relay device of the first embodiment is shown.

[0015] Fig. 9 The time graph shows the values ​​of some elements during the operation of the semiconductor relay device of the first embodiment.

[0016] Fig.10 The relationship between the temperature of the receiving circuit and the voltage of the control signal according to the first embodiment is shown.

[0017] Fig.11 An application example of the semiconductor relay device according to the first embodiment is shown.

[0018] Fig.12 A circuit configuration of a semiconductor relay device according to a modified example of the first embodiment is shown. DETAILED DESCRIPTION

[0019] In the following description, components having substantially the same function and structure are denoted by the same reference numerals, and duplicate description may be omitted.

[0020] In the present specification and claims, “connection” between a first element and a second element includes a case where the first element is directly connected to the second element or is always or selectively connected via a conductive element.

[0021] 1. First Implementation

[0022] 1.1. Structure

[0023] 1.1.1. System

[0024] Figure 1 FIG. 7 shows the functional blocks of the system 700 of the first embodiment. The system 700 can be implemented as an air conditioning device, for example. Figure 1 As shown, the system 700 includes an input-side device 500 , a semiconductor relay device 100 , and an output-side device 600 .

[0025] The input side device 500 sends an input signal Sin to the semiconductor relay device 100. The input signal Sin is an electrical signal that transmits information for controlling the on or off state of the output side device 600. When the system 700 is an air conditioning device, an example of the input side device 500 includes a remote controller. When the system 700 is an air conditioning device, an example of the input signal Sin includes a signal for controlling a thermostat.

[0026] The output side device 600 is connected to the semiconductor relay device 100, and is turned on or off based on the control of the input side device 500 via the semiconductor relay device 100. When the system 700 is an air conditioner, an example of the output side device 600 includes a motor that controls a solenoid valve.

[0027] The semiconductor relay device 100 receives an input signal Sin, and turns the output side device 600 on or off according to the input signal Sin while keeping the input side device 500 and the output side device 600 electrically separated. The semiconductor relay device 100 uses any coupling that can transmit a signal. Examples of coupling include capacitive coupling, magnetic coupling, and optical coupling. The semiconductor relay device 100 can be, for example, a semiconductor component including a plurality of chips (semiconductor chips) having semiconductor elements and a package that seals the semiconductor chips.

[0028] The semiconductor relay device 100 includes a transmission circuit 200 , a reception circuit 300 , and a switch circuit 400 .

[0029] The transmission circuit 200 generates an input signal Inr according to the input signal Sin. The transmission circuit 200 may be, for example, a semiconductor chip. The details of the transmission circuit 200 depend on the form of coupling used by the semiconductor relay device 100. The form of the input signal Inr depends on the form of coupling used by the semiconductor relay device 100. A specific example of the transmission circuit 200 is described later.

[0030] The receiving circuit 300 is insulated and separated from the transmitting circuit 200. The receiving circuit 300 can transmit signals and is coupled to the transmitting circuit 200 in any manner other than electrical coupling. That is, the receiving circuit 300 can receive an input signal Inr depending on the coupling method used by the semiconductor relay device 100. The details of the receiving circuit 300 are based on the coupling form of the transmitting circuit 200 and the receiving circuit 300. The receiving circuit 300 generates a control signal SC according to the input signal Inr. The receiving circuit 300 can be, for example, a semiconductor chip. The receiving circuit 300 will be further described later.

[0031] The switch circuit 400 is connected to the terminal TM1 at one end and to the terminal TM2 at the other end. The switch circuit 400 receives the control signal SC and is turned on or off according to the control signal SC, that is, the terminal TM1 and the terminal TM2 are electrically connected or disconnected. The control signal SC can take a state in which the switch circuit 400 is turned on, or a state in which the switch circuit 400 is disconnected. Hereinafter, the state in which the control signal SC turns on the switch circuit 400 is sometimes referred to as the control signal SC being in the on-indicating state. On the other hand, the state in which the control signal SC turns off the switch circuit 400 is sometimes referred to as the control signal SC being in the off-indicating state. The switch circuit 400 can be, for example, a semiconductor chip. The switch circuit 400 is turned on according to the control signal SC, that is, the terminal TM1 and the terminal TM2 are electrically connected. In addition, the switch circuit 400 is disconnected according to the control signal SC, that is, the terminal TM1 and the terminal TM2 are electrically non-conductive. The switch circuit 400 constitutes a part of the path (current path) through which the current required for the operation of the output side device 600 flows. When the switch circuit 400 is turned on, a current path of the output side device 600 is formed, and the output side device 600 can work, that is, the output side device 600 is turned on. When the switch circuit 400 is turned off, no current path of the output side device 600 is formed, and the output side device 600 cannot work, that is, the output side device 600 is turned off.

[0032] The receiving circuit 300 is further described. The receiving circuit 300 includes a protection circuit unit 1, a control circuit unit 2, and a conversion circuit unit 3. The control circuit unit 2 suppresses the voltage of the electric signal obtained by conversion by the conversion circuit unit 3 to a level not exceeding a certain level.

[0033] The protection circuit unit 1 protects the output side device 600 from the influence of overheating and / or excessive current (hereinafter, sometimes referred to as overcurrent) of the semiconductor relay device 100. That is, the protection circuit unit 1 puts the control signal SC into a disconnection indication state according to overheating and / or the flow of overcurrent. The protection circuit unit 1 includes an overheat protection circuit unit 10 and an overcurrent protection circuit unit 11. The overheat protection circuit unit 10 puts the control signal SC into a disconnection indication state according to the temperature of the semiconductor relay device 100, especially the temperature of the overheat protection circuit unit 10 exceeding a certain value. The overcurrent protection circuit unit 11 puts the control signal SC into a disconnection indication state according to the current exceeding a certain value flowing in the receiving circuit 300.

[0034] 1.1.2. Transmitting circuit and conversion circuit

[0035] As described above, the transmission circuit 200 and the reception circuit 300 are coupled in any form that can transmit signals, and the details of the transmission circuit 200 and the reception circuit 300, especially the details of the conversion circuit unit 3, depend on the coupling form. Hereinafter, examples of the details of the transmission circuit 200 and the details of the reception circuit 300 in several coupling modes are described.

[0036] Figure 2 The circuit configuration and functional blocks of the semiconductor relay device 100 of the first embodiment in the case of the first coupling type are shown. Specifically, Figure 2 An example of a circuit configuration and functional blocks of the semiconductor relay device 100 is shown when the semiconductor relay device 100 is a magnetic coupling type semiconductor relay device, that is, when the transmission circuit 200 and the reception circuit 300 are magnetically coupled.

[0037] like Figure 2 As shown, the transmitting circuit 200 includes an oscillator 201 , NAND gates 202 and 203 , and a coil 204 .

[0038] The oscillator 201 outputs a clock signal having a period at an output terminal Q. The oscillator 201 outputs a clock signal having a phase difference of 180° with the AC signal output from the output terminal Q at an output terminal -Q.

[0039] The NAND gate 202 is connected to the output terminal Q of the oscillator 201 at a first input terminal. The NAND gate 202 receives an input signal Sin at a second input terminal. The NAND gate 202 is connected to a first terminal (one end) of the coil 204 at an output terminal.

[0040] The NAND gate 203 is connected to the output terminal -Q of the oscillator 201 at a first input terminal. The NAND gate 203 receives an input signal Sin at a second input terminal. The NAND gate 203 is connected to the second terminal (the other end) of the coil 204 at an output terminal.

[0041] exist Figure 2 In the example of , the input signal Inr is a magnetic signal generated by electromagnetic induction of the coil 204.

[0042] The conversion circuit unit 3 includes diodes 301 , 302 , 303 , and 304 , a coil 305 , a capacitor 306 , and a resistor 307 .

[0043] The diode 301 is connected to the node N1 at its anode. The diode 301 is connected to the anode of the diode 302 at its cathode. The diode 302 is connected to the node N2 at its cathode.

[0044] The diode 303 is connected to the node N1 at its anode. The diode 303 is connected to the anode of the diode 304 at its cathode. The diode 304 is connected to the node N2 of the receiving circuit 300 at its cathode.

[0045] The coil 305 is connected to the cathode of the diode 301 and the anode of the diode 302 at a first terminal (one end). The coil 305 is connected to the cathode of the diode 303 and the anode of the diode 304 at a second terminal (the other end).

[0046] The capacitor 306 is connected to the node N1 at a first terminal (one end) and is connected to the node N2 at a second terminal (the other end).

[0047] The resistor 307 is connected to the node N1 at a first terminal (one end) and connected to the node N2 at a second terminal (the other end).

[0048] The coil 305 converts the input signal Sin into an AC electrical signal by generating a potential difference based on the input signal Sin at both ends of the coil 305. The diodes 301 to 304, the capacitor 306, and the resistor 307 convert the AC current generated by the coil 305 into a smoothed DC current. The smoothed DC current flows to the switch circuit 400 via the control circuit unit 2 and the overheat protection circuit unit 10. Furthermore, a charge pump circuit (not shown) may be inserted between the transmission circuit 200 and the switch circuit 400.

[0049] Figure 3 The circuit configuration and functional blocks of the semiconductor relay device 100 of the first embodiment in the case of the second coupling type are shown. Specifically, Figure 3An example of a circuit configuration and functional blocks of the semiconductor relay device 100 is shown when the semiconductor relay device 100 is a capacitive coupling type semiconductor relay device, that is, when the transmission circuit 200 and the reception circuit 300 are capacitively coupled.

[0050] like Figure 3 As shown, the transmission circuit 200 includes an oscillator 201 , a p-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 211 , inverters 212 and 213 , a first terminal (one end) of a capacitor 214 , and a first terminal (one end) of a capacitor 215 .

[0051] The positive electrode of the transmission circuit 200 receives the input signal Sin. The positive electrode is connected to the source of the transistor 211. The drain of the transistor 211 is connected to the positive input terminal of the oscillator 201. The negative electrode of the transmission circuit 200 is connected to the negative input terminal of the oscillator 201 and the gate of the transistor 211.

[0052] An output terminal Q of the oscillator 201 is connected to an input terminal of the inverter 212. An output terminal of the inverter 212 is connected to a first terminal of the capacitor 214.

[0053] An output terminal -Q of the oscillator 201 is connected to an input terminal of the inverter 213. An output terminal of the inverter 213 is connected to a first terminal of the capacitor 215.

[0054] exist Figure 3 In the example of , the input signal Inr is an electric signal based on the charges accumulated in the capacitors 214 and 215 .

[0055] The conversion circuit unit 3 includes diodes 301, 302, 303, and 304, a capacitor 306, and a resistor 307. The diodes 301, 302, 303, and 304, the capacitor 306, and the resistor 307 are connected to the magnetic coupling type semiconductor relay device 100 ( Figure 2 ) is connected in the same manner. The conversion circuit unit 3 includes the second terminal (the other end) of the capacitor 214 and the second terminal (the other end) of the capacitor 215, instead of the magnetic coupling ( Figure 2 ) under the coil 305.

[0056] The second terminal of the capacitor 214 is connected to the cathode of the diode 301 and the anode of the diode 302. The second terminal of the capacitor 215 is connected to the cathode of the diode 303 and the anode of the diode 304.

[0057] The capacitors 214 and 215 accumulate charges based on the input signal Sin and release the accumulated charges. An alternating current is generated based on the released charges. The diodes 301 to 304, the capacitor 306, and the resistor 307 convert the alternating current generated by the capacitors 214 and 215 into a smoothed direct current. The smoothed direct current flows to the switch circuit 400 via the control circuit unit 2 and the overheat protection circuit unit 10. Furthermore, a charge pump circuit (not shown) may be inserted between the transmission circuit 200 and the switch circuit 400.

[0058] Figure 4 FIG. 2 shows a circuit configuration of the semiconductor relay device 100 of the first embodiment in the case of the third coupling type. Specifically, Figure 4 An example of the circuit configuration of the semiconductor relay device 100 is shown when the semiconductor relay device 100 is a photocoupled semiconductor relay device, that is, when the transmission circuit 200 and the reception circuit 300 are photocoupled. Figure 4 An example of the circuit configuration of the control circuit unit 2 and the overheat protection circuit unit 10 is also shown. Figure 4 Only a portion of the transmission circuit 200 is shown, in particular the portion related to the output.

[0059] like Figure 4 As shown, the transmission circuit 200 includes a light emitting diode 221. The light emitting diode 221 is connected to the node N11 of the transmission circuit 200 at the anode. The light emitting diode 221 is connected to the node N12 of the transmission circuit 200 at the cathode. The node N12 has a potential lower than the potential of the node N11. The light emitting diode 221 emits light based on the input signal Sin. Figure 4 In the example, the input signal Inr is an optical signal based on the light emitted by the light emitting diode 221.

[0060] exist Figure 4 In the example of FIG. 2 , the light emitting diode 221 is driven by a constant current. Alternatively, the light emitting diode 221 may be driven by a constant voltage via a resistor (not shown) connected in series with the light emitting diode 221 .

[0061] The conversion circuit section 3 includes a plurality of photodiodes 311 connected in series. One end of the group of photodiodes 311 connected in series is connected to the node N1, and the other end is connected to the node N2. That is, each photodiode 311 other than one photodiode 311 at one end of the group of photodiodes 311 connected in series is connected to the cathode of the other photodiodes 311 at the anode. One photodiode 311 at one end of the group of photodiodes 311 connected in series is connected to the node N2. One photodiode 311 at the other end of the group of photodiodes 311 connected in series is connected to the node N1 at the cathode. During the period when the group of photodiodes 311 receives the input signal Inr, the group of photodiodes 311 generates a photoelectromotive force Vs from the node N1 to the node N2. Through the photoelectromotive force Vs, the current Iint flows through the node N2.

[0062] The control circuit unit 2 may have any structure as long as it keeps the voltage generated between the node N1 and the node N3 at a value not exceeding a certain value based on the current Iint flowing through the node N2. For example, the control circuit unit 2 includes an n-type MOSFET 21, an npn-type bipolar transistor 22, a plurality of diodes 23, a resistor 24, and a diode 25.

[0063] The transistor 21 has a source connected to the node N2 and a drain connected to the node N1. The gate of the transistor 21 is connected to one end of the resistor 24. The other end of the resistor 24 is connected to the node N1.

[0064] A plurality of diodes 23 are connected in series between the node N1 and the gate of the transistor 21. One diode 23 at one end of the group of diodes 23 connected in series is connected to the node N1 at its anode. One diode 23 at the other end of the group of diodes 23 connected in series is connected to the gate of the transistor 21 at its cathode.

[0065] The transistor 22 is connected to the node N2 at its collector, connected to the node N1 at its base, and connected to the node N3 at its emitter.

[0066] The diode 25 is connected to the node N3 at its anode and to the node N1 at its cathode.

[0067] The overheat protection circuit unit 10 includes n (n is a natural number greater than or equal to 2) diodes 101, a resistor 102, a thyristor 103, and a Zener diode 104. The overheat protection circuit unit 10 is connected to a node N3 of the control circuit unit 2 at a node N5.

[0068] The Zener diode 104 is connected to the node N5 at the anode. The Zener diode 104 is connected to the node N2 at the cathode. A potential used as a control signal SC appears at the node N2. During the period of receiving the application of a reverse voltage exceeding a certain magnitude, the Zener diode 104 generates a breakdown voltage or Zener voltage Vz between the cathode and the anode with the cathode as the high potential. The Zener diode 104 has a characteristic of generating a breakdown voltage Vz smaller than the magnitude of the photoelectromotive force Vs between the node N2 and the node N5.

[0069] The n diodes 101 are connected in series between the node N2 and the node N6. A diode 101 at one end of the group of diodes 101 connected in series is connected to the node N2 at the anode. A diode 101 at the other end of the group of diodes 101 connected in series is connected to the node N6 at the cathode. That is, the n diodes 101 include the first diode 101 to the nth diode 101, and for all cases where i (i is a natural number greater than 2) is greater than 2 and less than n-1, the i-th diode 101 is connected to the cathode of the (i-1)th diode at the anode. The first diode 101 is connected to the node N2 at the anode. The n-th diode 101 is connected to the cathode of the (n-1)th diode 101 at the anode, and the number n of diodes 101 connected to the node N6 at the cathode will be further described later.

[0070] The resistor 102 is connected to the node N6 at a first terminal (one end) and is connected to the node N5 at a second terminal (the other end).

[0071] The thyristor 103 has an anode connected to the node N2 and a cathode connected to the node N5. The thyristor 103 has a control terminal connected to the node N6.

[0072] The switch circuit 400 may have any structure as long as it can electrically connect or disconnect the terminal TM1 and the terminal TM2 according to the control signal SC. As an example, the switch circuit 400 includes n-type MOSFETs 401 and 402. The transistor 401 is connected to the terminal TM1 at the drain and to the node N5 at the source. The transistor 401 is connected to the node N2 at the gate.

[0073] The transistor 402 is connected to the terminal TM2 at the drain and to the node N5 at the source. The transistor 402 is connected to the node N2 at the gate. As described below, the transistors 401 and 402 are turned on when receiving the breakdown voltage Vz. The breakdown voltage Vz is higher than the threshold voltage of the transistors 401 and 402 to ensure that the transistors 401 and 402 are reliably turned on during the period when the gate is subjected to the breakdown voltage Vz.

[0074] 1.1.3 Number of diodes

[0075] The number n of diodes 101 is determined to satisfy the following conditions. Each diode 101 has a characteristic that depends on temperature. That is, the higher the temperature of the diode 101, the lower the forward voltage Vf generated by each diode 101. The semiconductor relay device 100 is configured to disconnect the switch circuit 400, that is, output a control signal SC indicating a disconnection state, when the temperature of the semiconductor relay device 100 exceeds a certain temperature Ts during the period of receiving the input signal Inr.

[0076] Hereinafter, the forward voltage of each diode 101 when the temperature Ti of each diode 101 is lower than the temperature Ts is referred to as the forward voltage Vfl. On the other hand, the forward voltage of each diode 101 when the temperature Ti is the temperature Ts is referred to as the forward voltage Vfh. In addition, the potential difference between the node N2 and the node N6 is referred to as the diode set terminal voltage Vds. Hereinafter, when the temperature Ti is lower than Ts, it is sometimes referred to as the normal temperature, and when the temperature Ti is higher than the temperature Ts, it is sometimes referred to as the high temperature.

[0077] The number n of diodes 101 is determined in such a way that the diode collective terminal voltage Vds during the period when the temperature Ti of each diode 101 is less than the temperature Ts and the diode collective terminal voltage Vds when the temperature Ti of each diode 101 is the temperature Ts satisfy the following conditions. Hereinafter, the diode collective terminal voltage Vds at normal temperature is sometimes referred to as the voltage at normal temperature Vdsl; the diode collective terminal voltage Vds at high temperature is sometimes referred to as the voltage at high temperature Vdsh.

[0078] Figure 5 The diode set terminal voltage at different temperatures of the first embodiment is shown. Figure 5 The left side of represents the voltage Vdsl at normal temperature. Figure 5 The right side of represents the voltage Vdsh at high temperature. Figure 5 The status shown on the left side of Figure 5 The number n of diodes 101 is determined in accordance with the state shown in the right part.

[0079] like Figure 5 As shown in the left part of , at normal temperature, the forward voltage Vfl is obtained, and therefore, the voltage Vdsl at normal temperature is Vfl×n. n is determined so that the voltage Vdsl at normal temperature (=Vfl×n) is higher than the breakdown voltage Vz.

[0080] like Figure 5 As shown in the right part of , the forward voltage Vfh is at high temperature, so the voltage Vdsh at high temperature is Vfh×n. n is determined so that the voltage Vdsh at high temperature (=Vfh×n) is lower than the breakdown voltage Vz.

[0081] Figure 6 The relationship between the number n of diodes in the semiconductor relay device according to the first embodiment and the temperature of the semiconductor relay device is shown. Figure 6 The vertical and horizontal axes of are represented by linear scales. As an example, it is assumed that the semiconductor relay device 100 is expected to perform an operation (overheat protection operation) to protect the output side device 600 from overheating between a certain temperature T5 and a temperature T6. Each plot represents the temperature at which the overheat protection operation starts. Figure 6 The actual verification results using semiconductor relay devices 100 trial-produced in various numbers n are shown. In addition, the verification results when the current Iint in the semiconductor relay device 100 is of various magnitudes are shown. As an example, the verification results when the current Iint is of certain magnitudes IE3, IE2, and IE1 are shown. IE2 is 10 times the magnitude of IE3. IE1 is 10 times the magnitude of IE2. Figure 6 In the above, the numbers Nm1 to Nm7 are respectively specific natural numbers.

[0082] like Figure 6 As shown, when the number n of diodes 101 is less than the number Nm5, the overheat protection operation starts at a temperature lower than the temperature T5 at any value of the current Iint. On the other hand, when the number n of diodes 101 is the number Nm6, the overheat protection operation starts at a desired temperature range, that is, above the temperature T5 and below the temperature T6, regardless of the value of the current Iint. Therefore, in this example, by selecting N6 as the number of diodes 101, the overheat protection operation within the desired temperature range can be achieved.

[0083] When overheat protection is expected to work in other temperature ranges, based on Figure 6 As shown in the relationship, by using a number other than the number Nm6 as the number n of the diodes 101, a desired overheat protection operation can be achieved.

[0084] 1.2. Work

[0085] Figure 7 and Figure 8 Each of the diagrams shows a state during operation of the semiconductor relay device 100 according to the first embodiment. Figure 7 Indicates the state at normal temperature. Figure 8 Indicates a state at high temperature. Figure 7 and Figure 8 Both show a state where an input signal Inr is supplied and a photoelectromotive force Vs is generated by the photodiode 311 .

[0086] like Figure 7As shown, by the supply of the input signal Sin, the current If flows through the light emitting diode 221. By the flow of the current If, the input signal Inr is generated. The input signal Inr is received by the photodiode 311. As a result, a photoelectromotive force Vs is generated. By the photoelectromotive force Vs, the current Iint flows through the node N2. The current Iint flows into the cathode of the Zener diode 104, thereby generating a breakdown voltage Vz between the node N5 and the node N2.

[0087] On the other hand, a voltage Vdsl at normal temperature is generated in the node N6 and the node N2, and the voltage Vdsl at normal temperature is higher than the breakdown voltage Vz. Therefore, no current flows from the node N2 to the node N6 of the group via the diode 101. Therefore, the thyristor 103 is disconnected. Therefore, the breakdown voltage Vz is maintained, and a control signal SC indicating the conduction state is generated according to the breakdown voltage Vz. By the control signal SC, the switch circuit 400 is turned on. That is, the transistors 401 and 402 are turned on, and the terminal TM1 and the terminal TM2 are electrically connected. Therefore, the potential difference Vo between the terminal TM1 and the terminal TM2 is zero. In addition, a current Io of a size such as the size of the load of the output side device 600 (not shown) connected to the switch circuit 400 flows through the transistors 401 and 402.

[0088] like Figure 8 As shown, the current Iint flows through the node N2 by the photoelectromotive force Vs. The current Iint flows into the cathode of the Zener diode 104, thereby generating a breakdown voltage Vz between the node N5 and the node N2.

[0089] However, a high temperature voltage Vdsh is generated in the node N6 and the node N2, and the high temperature voltage Vdsh is lower than the breakdown voltage Vz. Therefore, the current flows from the node N2 to the node N6 of the group via the diode 101. The current and the voltage generated by the resistor 102 are applied to the control terminal of the thyristor 103, and the thyristor 103 is turned on. Through the conduction of the thyristor 103, a current path from the node N2 to the node N5 via the thyristor 103 is formed, and the current flows from the node N2 to the node N5. Therefore, the node N2 and the node N5 are not maintained at the breakdown voltage Vz. Therefore, the control signal SC of the on-state indication state is not provided. In other words, the control signal SC of the off-state indication state is supplied. Therefore, the switch circuit 400 is turned off. That is, the transistors 401 and 402 are turned off, and the terminal TM1 and the terminal TM2 are electrically non-conductive. Between the terminal TM1 and the terminal TM2, a potential difference Vo of a certain size is generated and the current Io does not flow.

[0090] After the thyristor 103 is temporarily turned on, even if the voltage applied to the control terminal of the thyristor 103 is stopped, the thyristor 103 is maintained in the turned-on state. Therefore, by turning on the thyristor 103, the potential difference between the node N5 and the node N2 disappears, and even after the current flowing through the group of diodes 101 disappears, the thyristor 103 remains turned on. That is, the switch circuit 400 remains turned off. As long as a certain amount of current (holding current) flows from the anode to the cathode through the thyristor 103, the thyristor 103 remains turned on. Therefore, after the diode 101 temporarily becomes high temperature, even if the input signal Inr is continuously supplied, the thyristor 103 remains turned on, and the switch circuit 400 remains turned off.

[0091] The turned-on thyristor 103 is turned off when the magnitude of the current flowing from the anode to the cathode is equal to or less than the holding current. In order to turn off the thyristor 103 (reset the thyristor), the supply of the input signal Inr may be stopped.

[0092] Fig. 9 The values ​​of some elements that change during the operation of the semiconductor relay device 100 of the first embodiment are shown along with time. Fig. 9 As shown, at the time of starting the operation shown in the figure, the current If is zero and the input signal Inr is not output. Therefore, the switch circuit 400 is off, the potential difference Vo has a certain value Vd, and the current Io is zero. In addition, the temperature Ti of the diode 101 is lower than the temperature Ts.

[0093] At time t1, a current Ifh of a certain magnitude begins to flow according to the change of the input signal Sin. The current If of magnitude Ifh flows until time t3. As the current If of magnitude Ifh flows, the input signal Inr is output, and the photoelectromotive force Vs of the photodiode 311 is generated, and the current Iint flows. Since the temperature Ti is lower than the temperature Ts, the receiving circuit 300 performs a reference Figure 7 The operation during the normal temperature period described above. That is, the receiving circuit 300 outputs the control signal SC indicating the conduction state. By the output of the control signal SC, the terminals TM1 and TM2 of the switch circuit 400 are electrically conductive, the potential difference Vo is zero, and the current Io has a certain magnitude Io1. The magnitude of the current Io depends on the magnitude of the load of the output side device 600 at the time t1.

[0094] From time t1, for some reason, the temperature Ti rises and reaches the temperature Ts at time t2. Therefore, in the switch circuit 400, a reference Figure 8 That is, the thyristor 103 of the overheat protection circuit unit 10 is turned on, and the receiving circuit 300 outputs the control signal SC of the off-instruction state. As a result, the potential difference Vo has the magnitude Vd again, and the magnitude of the current Io becomes zero.

[0095] As reference Figure 8 As described above, the state after the temperature Ti reaches the temperature Ts can be maintained as long as the holding current flows through the thyristor 103. Therefore, after the time t2, even if the current If of the magnitude Ifh flows, the magnitude of the potential difference Vo and the magnitude of the current Io can be maintained. That is, the state formed at the time t2 continues until the time t3 when the current If of the magnitude Ifh stops. Fig. 9 In the example, the decrease starts from time t2.

[0096] At time t3, the magnitude of the current If is zero. As a result, the magnitude of the current flowing through the thyristor 103 of the overheat protection circuit unit 10 becomes lower than the holding current, and the thyristor 103 is turned off. That is, the overheat protection operation of the receiving circuit 300 is stopped. Although the thyristor 103 is turned off, the current If of magnitude Ifh does not flow. Therefore, the potential difference Vo maintains magnitude Vd even at time t3, and the magnitude of the current Io is zero.

[0097] At time t4, the magnitude of current If becomes Ifh again. Also, at time t4, temperature Ti is lower than temperature Ts. Therefore, receiving circuit 300 can operate during normal temperature, potential difference Vo becomes zero, and current Io has magnitude Io2.

[0098] 1.3. Advantages (effects)

[0099] According to the first embodiment, as described below, it is possible to provide a semiconductor relay device that can protect output-side devices from overheating even if no external power source is included on the secondary side, which is the output side.

[0100] Overheat protection can be achieved by utilizing the temperature dependence of the forward voltage of the diode. As a general method, a reference voltage is applied to the non-inverting input of the operational amplifier, and a diode is connected to the inverting input. When the forward voltage of the diode rises due to heating and the voltage of the inverting input falls below the reference voltage, the output of the operational amplifier reverses and the overheat protection starts. In this method, a constant current source or a constant voltage source is required to supply current to the diode.

[0101] On the other hand, several semiconductor relay devices such as the semiconductor relay device 100 of the first embodiment include: a transmitting circuit and a receiving circuit coupled in an insulated and separated manner by magnetism, capacitance, light, etc. The receiving circuit operates using a tiny current or voltage based on an input signal, and does not include a constant current source and a constant voltage source. The above-mentioned input signal is a magnetic signal from the transmitting circuit, an electrical signal based on capacitance, and an optical signal. When the receiving circuit in such a semiconductor relay device has an overheat protection function, it is necessary to operate the circuit for overheat protection by using a current or voltage generated based on the input signal from the transmitting circuit. However, by using a tiny current or voltage generated according to the input signal in the overheat protection circuit, sometimes the original operation of the receiving circuit is hindered, that is, the performance of turning on or off the switch circuit 400 is hindered.

[0102] In addition, sometimes a protection circuit such as an overheat protection circuit is provided outside the chip of the receiving circuit. In this case, the protection circuit is provided on a circuit substrate on which the receiving circuit chip is mounted in the semiconductor relay device. This requires the circuit substrate to have a larger area. In addition, the design of the semiconductor relay device including the operation of the protection circuit is also relatively complicated.

[0103] The receiving circuit 300 of the first embodiment includes a Zener diode 104, a plurality of diodes 101, and a thyristor 103. The Zener diode 104 generates a voltage to be supplied to the switch circuit 400. The plurality of diodes 101 are connected in series in an anti-parallel manner to the Zener diode 104. The thyristor 103 has a control terminal connected in anti-parallel to the Zener diode 104 and connected to one end of the group of the plurality of diodes 101. By supplying an input signal Inr to the receiving circuit 300, a breakdown voltage Vz is output as a control signal SC during a period when the receiving circuit 300 is at a normal temperature. On the other hand, when the receiving circuit 300 reaches a certain temperature Ts, a current flows through the diode 101 whose forward voltage Vf is reduced, and the thyristor 103 is turned on by the current, and the voltage of the control signal SC is pulled to the ground voltage, so that the switch circuit 400 is turned off, thereby starting the overheat protection operation.

[0104] During the normal temperature period, the potential difference between the two ends of the diode 101 group, that is, the voltage Vdsl at the normal temperature is less than the breakdown voltage Vz, so the current does not flow through the diode 101. Therefore, during the normal temperature period, the overheat protection circuit unit 10 does not consume current. In addition, the drop in the voltage of the control signal SC is caused by the conduction of the thyristor 103. When the thyristor 103 is temporarily turned on, it maintains the state of conduction autonomously, and no current is required to maintain this state. Therefore, after the overheat protection operation starts, the receiving circuit 300 can continue to perform the overheat protection operation without relying on the presence or absence of the input signal Inr. In addition, since the overheat protection circuit unit 10 does not need to continuously consume current or voltage, it will not hinder the operation of the receiving circuit 300. Therefore, even if the receiving circuit 300 does not include a constant current source, it can take into account the execution of the original operation and the overheat protection operation.

[0105] Fig.10 The relationship between the temperature of the receiving circuit 300 and the voltage of the control signal SC according to the first embodiment is shown. Fig.10 The number of diodes 101 is shown as Figure 6 Example of N6 shown.

[0106] like Fig.10 As shown in FIG. 1 , the current Iint is constant when the current is IE1, IE2, and IE3 until the temperature T5. When the temperature exceeds T5, the current Iint decreases significantly. This means that when the temperature exceeds T5, the overheat protection operation has begun. Figure 6 As described above, it means that the overheat protection operation between the temperature T5 and the temperature T6 occurs as expected.

[0107] In addition, the start of the overheat protection operation is based on the timing of the thyristor 103 being turned on, and the timing of the thyristor 103 being turned on is based on the number n of diodes 101 connected in series. This makes it easy to design a receiving circuit 300 that starts the overheat protection operation within the desired temperature range. That is, for example, it can be considered to use the size of a certain resistor as a dominant factor to set the timing of the thyristor being turned on. However, changing the size of a certain resistor at the design stage will affect a wide range of parts of the circuit, making the design difficult. In addition, it is sometimes not easy to form a resistor of the size designed. Therefore, using the size of the resistor as a dominant factor will make it difficult to design and implement a circuit containing such an element. On the other hand, according to the first embodiment, as shown in reference Figure 6 As described above, the timing of the thyristor 103 turning on can be set according to the number n of the diodes 101, and thus the timing of the overheat protection operation starting can be set. Figure 6It can be seen that the desired temperature range for starting the overheat protection operation can be easily achieved by adjusting the number n of diodes 101. In addition, it is easier to form the diodes 101 with the number n as designed than to fine-tune the size of the resistor. Therefore, compared with the case where the size of the resistor is used as the dominant factor, it is easier to form the receiving circuit 300 that performs the overheat protection operation in the desired temperature range.

[0108] 1.4. Modifications and Application Examples

[0109] like Fig.11 As shown, the semiconductor relay device 100 may include a protection mechanism for the switch circuit 400 against application of an overvoltage such as a surge. Fig.11 An application example of the semiconductor relay device 100 according to the first embodiment is shown, and another example of the switch circuit 400 is shown.

[0110] like Fig.11 As shown, the switch circuit 400 further includes Zener diodes 411 to 418 .

[0111] The Zener diodes 411 and 412 are connected to each other at their respective anodes. The cathode of the Zener diode 411 is connected to the gate of the transistor 401. The cathode of the Zener diode 412 is connected to the terminal TM1 and the drain of the transistor 401.

[0112] The Zener diodes 413 and 414 are connected to each other at their respective anodes. The cathode of the Zener diode 413 is connected to the gate of the transistor 401. The cathode of the Zener diode 414 is connected to the source of the transistor 401.

[0113] The Zener diodes 415 and 416 are connected to each other at their respective anodes. The cathode of the Zener diode 415 is connected to the gate of the transistor 402. The cathode of the Zener diode 416 is connected to the source of the transistor 402.

[0114] The Zener diodes 417 and 418 are connected to each other at their respective anodes. The cathode of the Zener diode 417 is connected to the gate of the transistor 402. The cathode of the Zener diode 418 is connected to the terminal TM2 and the drain of the transistor 402.

[0115] The receiving circuit 300 or the receiving circuit 300 and the switching circuit 400 may have Fig.12 The structure described below is shown. Fig.12 A circuit configuration of a semiconductor relay device according to a modified example of the first embodiment is shown.

[0116] like Fig.12 As shown, except Figure 4 In addition to the structure shown, the semiconductor relay device 100 further includes switches SW1 and SW2.

[0117] The switch SW1 is, for example, an n-type MOSFET. Fig.12 The switch SW1 is connected to the anode of the thyristor 103 at one end and to the gates of the transistors 401 and 402 at the other end. The switch SW1 may be included in the receiving circuit 300 or in the switch circuit 400 . Fig.12 An example is shown in which the switch SW1 is included in the receiving circuit 300 (particularly, the overheat protection circuit unit 10 ).

[0118] The switch SW2 is, for example, an n-type MOSFET. Fig.12 Such an example is shown. The switch SW2 is connected to the gates of the transistors 401 and 402 at one end and to the node N5 at the other end. The switch SW2 may be included in the receiving circuit 300 or in the switch circuit 400 . Fig.12 An example is shown in which the switch SW2 is included in the receiving circuit 300 (particularly, the overheat protection circuit unit 10 ).

[0119] The switches SW1 and SW2 are turned on complementarily, that is, one is turned on while the other is turned off, and receive signals at their respective control terminals (when the switches SW1 and SW2 are transistors, at their respective gates). The on and off control of the switches SW1 and SW2 can be performed, for example, by the potential on the node N6.

[0120] Alternatively, the on and off control of the switches SW1 and SW2 may be performed by making one of the switches a normally-on transistor and the other a normally-off transistor.

[0121] Alternatively, the on and off control of the switches SW1 and SW2 can be performed by providing a signal from a logic circuit (not shown) to each control terminal of the switches SW1 and SW2. The logic circuit receives the potential on the node N6, converts the potential on the node N6 into a digital signal, and provides a signal based on the converted digital signal to the control terminals of the switches SW1 and SW2. The power required for the operation of the logic circuit can be provided by a photoelectromotive force generated by receiving an input signal Inr by a group of photodiodes connected in series similar to the group of photodiodes 311.

[0122] According to such a structure, when the control signal SC is in the on-indicating state (with Figure 7 In the case where the control signal SC is in the off-indicating state (same as the thyristor 103 is in the off-state), the switch SW1 is turned on and the switch SW2 is turned off. Therefore, the transistors 401 and 402 are turned on, and the gates of the transistors 401 and 402 are not connected to the node N5. On the other hand, when the control signal SC is in the off-indicating state (same as the thyristor 103 is in the off-state), the switch SW1 is turned on and the switch SW2 is turned off. Therefore, the transistors 401 and 402 are turned on, and the gates of the transistors 401 and 402 are not connected to the node N5. Figure 8In the case where the thyristor 103 is in the on state), the switch SW1 is turned off and the switch SW2 is turned on. Therefore, through the switch SW2, the gates of the transistors 401 and 402 are connected to the node N5. By such operation, the transistors 401 and 402 are turned on or off based on the conduction or disconnection of the thyristor 103. Figure 4 Therefore, for example, the difference between the impedance of the thyristor 103 during the on-time and the impedance during the off-time, and / or the deviation of the magnitude of the input signal Inr can prevent the transistors 401 and 402 from turning on and off as intended.

[0123] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope or subject matter of the invention, and are also included in the invention described in the claims and the scope of their equivalents.

Claims

1. A semiconductor relay device comprising: a conversion circuit unit that receives an input signal from the outside and causes a first current to flow through the first node based on the input signal; a Zener diode having an anode connected to the second node and a cathode connected to the first node; n diodes, the n diodes are connected in series, an anode of a diode at a first end of the n diodes is connected to the first node, and a cathode of a diode at a second end of the n diodes is connected to a third node; a thyristor comprising an anode connected to the first node, a cathode connected to the second node, and a control terminal connected to the third node; as well as A transistor has a gate connected to the first node.

2. The semiconductor relay device according to claim 1, wherein The n diodes include the first diode to the nth diode, When i is a natural number greater than or equal to 2 and less than or equal to n-1, the anode of the i-th diode is connected to the cathode of the i-1-th diode. The first diode is connected to the first node at an anode. The nth diode is connected to the cathode of the (n-1)th diode at an anode and to the third node at a cathode.

3. The semiconductor relay device according to claim 1, wherein The conversion circuit unit outputs a first voltage between the first node and a fourth node while receiving the input signal. A breakdown voltage of the Zener diode is lower than the first voltage.

4. The semiconductor relay device according to claim 2, wherein: The conversion circuit unit outputs a first voltage between the first node and a fourth node while receiving the input signal. A breakdown voltage of the Zener diode is lower than the first voltage.

5. The semiconductor relay device according to claim 3, wherein: The breakdown voltage is higher than a threshold voltage of the transistor.

6. The semiconductor relay device according to claim 4, wherein: The breakdown voltage is higher than a threshold voltage of the transistor.

7. The semiconductor relay device according to claim 6, wherein: Each of the n diodes has a forward voltage of a first magnitude when the diode is at a first temperature, and has a forward voltage of a second magnitude smaller than the first magnitude when the diode is at a second temperature higher than the first temperature.

8. The semiconductor relay device according to any one of claims 1 to 5, wherein: Each of the n diodes has a forward voltage of a first magnitude when the diode is at a first temperature, and has a forward voltage of a second magnitude smaller than the first magnitude when the diode is at a second temperature higher than the first temperature.

9. The semiconductor relay device according to claim 3, wherein: The n diodes generate a first forward voltage between the second end and the first end when at a first temperature, and generate a second forward voltage when at a second temperature higher than the first temperature. The first forward voltage is higher than the breakdown voltage, The second forward voltage is lower than the breakdown voltage.

10. The semiconductor relay device according to claim 4, wherein: The n diodes generate a first forward voltage between the second end and the first end when at a first temperature, and generate a second forward voltage when at a second temperature higher than the first temperature. The first forward voltage is higher than the breakdown voltage, The second forward voltage is lower than the breakdown voltage.

11. The semiconductor relay device according to claim 5, wherein: The n diodes generate a first forward voltage between the second end and the first end when at a first temperature, and generate a second forward voltage when at a second temperature higher than the first temperature. The first forward voltage is higher than the breakdown voltage, The second forward voltage is lower than the breakdown voltage.

12. The semiconductor relay device according to claim 6, wherein: The n diodes generate a first forward voltage between the second end and the first end when at a first temperature, and generate a second forward voltage when at a second temperature higher than the first temperature. The first forward voltage is higher than the breakdown voltage, The second forward voltage is lower than the breakdown voltage.

13. The semiconductor relay device according to any one of claims 1 to 7 and 9 to 12, wherein: A transmission circuit is further provided for outputting the input signal.

14. The semiconductor relay device according to claim 8, wherein A transmission circuit is further provided for outputting the input signal.

15. The semiconductor relay device according to claim 13, wherein: The transmitting circuit is a light emitting diode, The conversion circuit section includes a photodiode.

16. The semiconductor relay device according to claim 14, wherein The transmitting circuit is a light emitting diode, The conversion circuit section includes a photodiode.

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