JP2003115756A - Drive circuit for semiconductor switch element and semiconductor relay using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive circuit for a semiconductor switch element which can shorten the turn on time and turn off time of the semiconductor switch element. SOLUTION: This drive circuit is equipped with a first light emitting element 11a which is lit continuously by a DC power source 12a, a solar cell 21 which is optically coupled with the first light emitting element 11a, and a photodiode 25 which is optically coupled with the second light emitting element 11b being lit intermittently by the pulse power source 12b. For the photodiode 25, the cathode is connected to the positive electrode terminal of the solar cell 21 and the anode is connected to the negative electrode terminal of the solar cell 21 via a bias resistor R3. Furthermore, a first semiconductor switch 27 consisting of a p-channel MOSFET is connected between both ends of the solar cell 21, and a second semiconductor switch 28 consisting of an n-channel MOSFET is inserted between the solar cell 21 and the first semiconductor switch 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a semiconductor switch element and a semiconductor relay using the drive circuit.

[0002]

2. Description of the Related Art In recent years, there is an increasing need for semiconductor switches as switching elements that can transmit high-frequency analog signals with high accuracy and can be turned on and off at high speed. Such a semiconductor switch includes a light emitting element such as a light emitting diode, a solar cell optically coupled to the light emitting element, and a pair of MOSFETs connected in anti-series, which is turned on / off by the output of the solar cell. A semiconductor relay including and is known.

A circuit diagram of this type of semiconductor relay is shown in FIG. 6 (see Japanese Patent Laid-Open No. 63-153916). The semiconductor relay shown in FIG. 6 is a light emitting element 1 including a light emitting diode.
1, a solar cell 21 that is optically coupled to the light emitting element 11 to generate a photoelectromotive force, and a gate terminal (hereinafter abbreviated as a gate).
And two source terminals (hereinafter abbreviated as sources) are commonly connected to each other in two n-channel MOSFEs.
The semiconductor switch element 22 composed of T22a and 22b is provided, and is configured to turn on / off the semiconductor switch element 22 in response to the electromotive force of the solar cell 21. It should be noted that the semiconductor switch element 22 is composed of n-channel MOSFs.
The drain terminals (hereinafter abbreviated as drains) of the ETs 22a and 22b respectively constitute main terminals and are connected to output terminals (relay output terminals) 26a and 26b.

Here, the light emitting element 11 is connected between both ends of the driving power source 12 via a resistor R1. The drive power supply 12 is composed of a pulse power supply that outputs a pulse voltage. A normally-on type (depletion type) in which a bias resistor R2 is connected between the gate and the source between the connection point between the gates and the connection point between the sources (between the control input terminals) in the semiconductor switch element 22 described above. ) N-channel MOSFET 23 is connected.
This normally-on type n-channel MOSFET 23 is
Each MOSFET 22a, 22 of the semiconductor switch element 22
It is provided to pull out the gate charge of b. Further, between the gate and source of the normally-on type n-channel MOSFET 23, the source and drain of the n-channel MOSFET 24 whose gate and drain are short-circuited are connected. The above-mentioned n-channel MOSFET 2
The gates of 2a and 22b are connected to the positive terminal of the solar cell 21, and the source is connected to the solar cell 21 via the bias resistor R2.
Is connected to the negative electrode terminal of.

In the semiconductor relay described above, the drive circuit for the semiconductor switch element 22 is constituted by the drive power source 12, the resistor R1, the light emitting element 11, the solar cell 21, the normally-on type n-channel MOSFET 23, the bias resistor R2, and the n-channel MOSFET 24. The semiconductor switch element 22 is configured to be able to conduct and block AC power.

The operation of the above drive circuit will be described below.

First, the operation when the semiconductor switch element 22 shifts from the off state to the on state will be described.

When a forward current flows from the driving power source 12 through the resistor R1 to the light emitting element 11, the light emitting element 11 emits light and the solar cell 21 generates a photoelectromotive force. The current due to this photovoltaic power first flows in the path of the positive electrode terminal of the solar cell 21, the drain of the normally-on type n-channel MOSFET 23, the source of the normally-on type n-channel MOSFET 23, the bias resistor R2-the negative terminal of the solar cell 21. . This current causes a voltage drop across the bias resistor R2 in the direction of reverse biasing between the gate and the source of the n-channel MOSFET 23, and when the voltage across the bias resistor R2 exceeds the threshold voltage of the n-channel MOSFET 23, the n-channel MOSFET 23 is turned on. High impedance. After this, most of the photovoltaic current of the solar cell 21 is the positive electrode terminal of the solar cell 21-n channel MO.
Each gate of SFETs 22a and 22b-n channel MOS
Sources of FETs 22a and 22b-Bias resistor R2-
Each n-channel M flowing in the path of the negative electrode terminal of the solar cell 21
The gates and sources of the OSFETs 22a and 22b are charged in the direction of forward bias. And this charging voltage is n
When the threshold voltages of the channel MOSFETs 22a and 22b are exceeded, the n-channel MOSFETs 22a and 22b are turned on. Furthermore, each n-channel MOSFET 22a,
After the gate-source of 22b is completely charged, the current due to the photovoltaic power passes through the normally-on type n-channel MOSFET 23 having a high impedance, and the positive terminal of the solar cell 21-normally-type n-channel MOSF.
ET23 drain-normally-on n-channel MO
Source of SFET23-bias resistance R2-solar cell 2
Continue to flow in the path of the negative electrode terminal of 1. This is because the normally-on type n-channel MOSFET 23 reaches the equilibrium state with a certain impedance because the current flowing therethrough maintains the high impedance state due to the voltage drop in the bias resistor R2. In this state, most of the current flowing through the bias resistor R2 is connected in parallel and adjusted to a medium impedance n.
The current flows through the channel MOSFET 24, and the voltage drop of the bias resistor R2 causes an n-channel MOSFET
The bias voltage between the gate and the source of 22a and 22b is prevented from decreasing and the on-resistance of the n-channel MOSFETs 22a and 22b does not increase.

In this state, the primary side circuit 10 including the light emitting element 11 and the secondary side circuit 2 including the solar cell 21.
Since it is electrically well isolated from 0 through a very small electrostatic capacity, the output terminal 26a to which each main terminal of the semiconductor switch element 22 of the secondary side circuit 20 is connected,
Also when a high frequency power supply is connected between 26b,
The high frequency impedance with the primary side circuit 10 having a large capacitance to ground (capacitance between a fixed potential) is very large. Therefore, the semiconductor relay having the configuration shown in FIG. 6 has excellent high-frequency characteristics (conduction characteristics of high-frequency signals between the output terminals 26a and 26b) when the semiconductor switching element 22 is conductive, and the output of the high-frequency power supply is the inductance of the circuit. It has a feature that the amount of dip drop caused by interference with the component and the capacitance to ground is very small. In short, it is possible to suppress the occurrence of a dip that maximizes the conduction loss at a specific frequency.

Next, the operation when the semiconductor switch element 22 shifts from the on state to the off state will be described.

When the output voltage of the driving power supply 12 becomes 0 V and the light emitting element 11 is turned off, the output current of the solar cell 21 decreases. Therefore, the voltage drop of the bias resistor R2 is reduced, and the normally-on type n-channel MOSFET 23 is in a low impedance state. Then, n-channel MOS
The charge accumulated between the gate and the source of the FETs 22a and 22b and the charge accumulated between the positive electrode terminal and the negative electrode terminal of the solar cell 21 are the n-channel MOSFET 23.
Through the n-channel MOSFETs 22a, 2
When the gate-source voltage of 2b falls below the threshold voltage, each n-channel MOSFET 22a, 22b is turned off.

The semiconductor relay configured as described above is
Each n-channel MOSFET 2 of the semiconductor switch element 22
N-channel MSOFT when 2a and 22b are turned on
The gate-sources of T22a and 22b operate so as to be charged in a relatively short time and turned on at high speed, and most of the output voltage of the solar cell 21 after the completion of charging is the gate-source of the n-channel MOSFETs 22a and 22b. It is applied between the n-channel MOSFETs 22a and 22b so that the n-channel MOSFETs 22a and 22b are maintained at low on-resistance. On the other hand, even when turned off, the n-channel MOSFETs 22a, 2
The charge accumulated between the gate and the source of 2b is discharged in a relatively short time and turned off at a high speed. Furthermore, since the electrostatic capacitance between the primary side circuit 10 and the secondary side circuit 20 is extremely small when the semiconductor switching element 22 is conducting, high frequency characteristics (output terminal 26a,
There is also an advantage that the conduction characteristic of the high frequency signal between 26b) is excellent.

[0013]

However, in the above-mentioned conventional drive circuit, at the time of turn-on, two n-channel MOSFETs forming the semiconductor switch element 22 are formed.
The normally-on type n-channel MOSFET 2 is provided before the forward bias between the gate and source of 22a and 22b.
Since the time for turning off 3 is required, there is a problem that the high speed of turn-on is not sufficiently satisfied.

Further, even at the time of turn-off, the two n-channel MOSFEs constituting the semiconductor switch element 22 are formed.
In addition to the gate-source capacitance of T22a and 22b, it is necessary to discharge a large terminal capacitance of the solar cell 21, that it takes time for the accumulated charge of the terminal capacitance of the solar cell 21 to disappear, Since the discharge current of the charges accumulated in the inter-terminal capacitance of the battery 21 operates the normally-on type n-channel MOSFET 23 to have a high impedance, the turn-off speed is not satisfied, and the speed is further increased. Is required.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a drive circuit for a semiconductor switch element, which can shorten the turn-on time and turn-off time of the semiconductor switch element.

[0016]

In order to achieve the above object, the invention of claim 1 is a drive circuit for a semiconductor switch element which is turned on / off according to a control input applied between control input terminals. A light emitting element of No. 1 and a solar cell optically coupled to the first light emitting element and capable of providing a control input for turning on the semiconductor switch element between the control input terminals;
A second light emitting element, a photodiode optically coupled to the second light emitting element, a first semiconductor switch connected between both ends of the solar cell and turned on / off by conduction / non-conduction of the photodiode, and the solar cell A second semiconductor switch which is inserted between the first semiconductor switch and is turned on / off in a complementary manner with the first semiconductor switch by conduction / non-conduction of the photodiode.
The semiconductor switch, the first driving means for continuously lighting the first light emitting element, and the second driving means for intermittently lighting the second light emitting element, and the second light emitting element is turned on. The first semiconductor switch is off while the second semiconductor switch is on while the second light emitting element is off, and the first semiconductor switch is on and the second semiconductor switch is off while the second light emitting element is off. As described above, the connection relationship between each semiconductor switch and the photodiode is set, and a solar cell having a relatively large inter-terminal capacitance is optically coupled to the first light emitting element that is continuously lit. Therefore, the solar cell is always charged, and the control input between the control input terminals of the semiconductor switch element depends on the states of the first semiconductor switch and the second semiconductor switch that are turned on and off complementarily. Will be changed, not necessary to charge and discharge the solar cell as in the prior art, the control input can be switched at high speed, it can shorten the turn-on and turn-off times of the semiconductor switch element.

According to a second aspect of the invention, in the first aspect of the invention, the cathode of the photodiode is connected to the positive terminal of the solar cell and the anode is connected to the negative terminal of the solar cell via a bias resistor, The first semiconductor switch is composed of a p-channel MOSFET, and the second semiconductor switch is an n-channel MOS.
The drain terminal and the gate terminal of the p-channel MOSFET and the n-channel MOSFET are commonly connected to each other, and the source terminal of the p-channel MOSFET is connected to the positive terminal of the solar cell. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell and the commonly connected gate terminal is connected to the anode of the photodiode, it is inserted between the solar cell and the semiconductor switch element. Since the second semiconductor switch is composed of an n-channel MOSFET, the second semiconductor switch is connected to the p-channel M-channel.
On-resistance can be reduced without increasing the element area of the second semiconductor switch occupying the semiconductor chip, as compared with the case where it is configured by the OSFET, which is advantageous in shortening the turn-on time.

According to a third aspect of the invention, in the first aspect of the invention, the cathode of the photodiode is connected to the positive terminal of the solar cell via a bias resistor and the anode is connected to the negative terminal of the solar cell. The first semiconductor switch is composed of an n-channel MOSFET and the second semiconductor switch is a p-channel MOS.
The drain terminal and the gate terminal of the n-channel MOSFET and the p-channel MOSFET are commonly connected to each other, and the positive terminal of the solar cell is connected to the source terminal of the p-channel MOSFET. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the cathode of the photodiode, the first terminal connected between both ends of the solar cell. Semiconductor switch is n-channel MOS
Since it is configured by the FET, it is possible to reduce the on-resistance without increasing the element area of the first semiconductor switch occupying the semiconductor chip as compared with the case where the first semiconductor switch is configured by the p-channel MOSFET. This is advantageous for shortening the turn-off time.

According to a fourth aspect of the present invention, there is provided a drive circuit for a semiconductor switch element which is turned on / off according to a control input applied between control input terminals, wherein the first light emitting element and the first light emitting element are optically coupled. A solar cell capable of providing a control input for turning on the semiconductor switch element between the control input terminals; a second light emitting element; a photodiode optically coupled to the second light emitting element; A first semiconductor switch connected between both ends and turned on / off by conduction / non-conduction of the photodiode, and a first semiconductor switch inserted between the solar cell and the first semiconductor switch by conduction / non-conduction of the photodiode A second semiconductor switch that is turned on and off complementarily to the first light emitting element, a first driving unit that continuously lights the first light emitting element, and a second light emitting element that intermittently lights the second light emitting element. The first semiconductor switch is on while the second light emitting element is on, the second semiconductor switch is off, and the first semiconductor switch is off while the second light emitting element is off. The semiconductor connection of each semiconductor switch and the photodiode is set so that the second semiconductor switch is turned off and the second semiconductor switch is turned on. Since the battery is optically coupled to the first light-emitting element that is continuously lit, the solar cell is always charged, and the states of the first semiconductor switch and the second semiconductor switch that are turned on and off complementarily As a result, the control input to the semiconductor switch element changes, and it is not necessary to charge and discharge the solar cell as in the past, so the control input can be switched at high speed. You can shorten the turn-on and turn-off times of the child.

According to a fifth aspect of the present invention, in the fourth aspect, the cathode of the photodiode is connected to the positive terminal of the solar cell via a bias resistor and the anode is connected to the negative terminal of the solar cell. The first semiconductor switch is composed of a p-channel MOSFET, and the second semiconductor switch is an n-channel MOS.
The drain terminal and the gate terminal of the p-channel MOSFET and the n-channel MOSFET are commonly connected to each other, and the source terminal of the p-channel MOSFET is connected to the positive terminal of the solar cell. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell and the commonly connected gate terminal is connected to the cathode of the photodiode, it is inserted between the solar cell and the semiconductor switch element. Since the second semiconductor switch is composed of an n-channel MOSFET, the second semiconductor switch is connected to the p-channel M-channel.
On-resistance can be reduced without increasing the element area of the second semiconductor switch occupying the semiconductor chip, as compared with the case where it is configured by the OSFET, which is advantageous in shortening the turn-on time. Further, since the photodiode becomes non-conductive when the second light emitting element is off, the p-channel MOSFET that is the first semiconductor switch is off and the n-channel MOSFET that is the second semiconductor switch. Is turned on, the semiconductor switch element can be turned on by turning off the second light emitting element.

According to a sixth aspect of the present invention, in the fourth aspect, the cathode of the photodiode is connected to the positive terminal of the solar cell and the anode is connected to the negative terminal of the solar cell through a bias resistor. The first semiconductor switch is composed of an n-channel MOSFET and the second semiconductor switch is a p-channel MOS.
The drain terminal and the gate terminal of the n-channel MOSFET and the p-channel MOSFET are commonly connected to each other, and the positive terminal of the solar cell is connected to the source terminal of the p-channel MOSFET. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell and the commonly connected gate terminal is connected to the anode of the photodiode, the first terminal connected between both ends of the solar cell. Semiconductor switch is n-channel MOS
Since it is configured by the FET, it is possible to reduce the on-resistance without increasing the element area of the first semiconductor switch occupying the semiconductor chip as compared with the case where the first semiconductor switch is configured by the p-channel MOSFET. This is advantageous for shortening the turn-off time. In addition, since the photodiode becomes non-conductive when the second light emitting element is off, the p-channel MOSFET that is the first semiconductor switch is off, and the n-channel MOS that is the second semiconductor switch.
Since the FET is turned on, the semiconductor switch element can be turned on by turning off the second light emitting element.

According to a seventh aspect of the present invention, there is provided a semiconductor switch element drive circuit according to any one of the first to sixth aspects, and the semiconductor switch element, wherein the semiconductor switch element has two electric fields. A control input terminal is provided between a connection point between the gate terminals of the effect transistor and a connection point between the source terminals thereof, and each drain terminal is configured as a main terminal, and the first semiconductor switch is connected between the control input terminals. In addition, the solar cell is connected via a second semiconductor switch, and for example, a series circuit of a load and an AC power source is connected between the main terminals of the semiconductor switch element. Can be used as
The semiconductor switching device can be turned on and off at high speed.

[0023]

(First Embodiment) In the present embodiment,
As shown in FIG. 1, a drive circuit for the semiconductor switch element 22 composed of an n-channel MOSFET is illustrated. In the present embodiment, the gate terminal (hereinafter abbreviated as a gate) -source terminal (hereinafter abbreviated as a source) of the n-channel MOSFET that is the semiconductor switching element 22 serves as the control input terminal, and the drain terminal (hereinafter , Abbreviated as drain) and a source respectively constitute a main terminal,
A gate voltage (gate-source voltage) applied between the gate and the source serves as a control input. Here, each main terminal is connected to the output terminals 26a and 26b, respectively.

The drive circuit in this embodiment includes a first light emitting element 11a formed of a light emitting diode, a solar cell 21 optically coupled to the first light emitting element 11a, and a second light emitting element 11b formed of a light emitting diode. , Second light emitting element 1
1b and a photodiode 25 optically coupled.

Here, the first light emitting element 11a is
The DC power supply 12a is connected across the resistor R1a, and the second light emitting element 11b is connected across the pulse power supply 12b via the resistor R1b. DC power supply 12
As for the output voltage of a, the solar cell 21 is the semiconductor switching element 2
It is set so that a gate voltage (gate-source voltage) that can maintain the on-state of the n-channel MOSFET of FIG. Therefore, the solar cell 2
1 is an n-channel M that constitutes the semiconductor switch element 22.
A gate voltage (gate-source voltage) for turning on the OSFET can be supplied. Pulse power supply 12b
Is a unipolar pulse power source that outputs a pulse voltage, and the output voltage can take two values, that is, a specified voltage larger than the ON voltage of the photodiode 25 and 0V (that is, two states are set). It can be taken).
In the present embodiment, the DC power supply 12a constitutes a first driving unit that continuously lights the first light emitting element 11a,
The pulsed power supply 12b constitutes a second drive means for intermittently lighting the second light emitting element 11b.

A series circuit of the above-mentioned photodiode 25 and bias resistor R3 is connected between both ends of the solar cell 21. Here, in the photodiode 25, the cathode is connected to the positive electrode terminal of the solar cell 21, and the anode is connected to the negative electrode terminal of the solar cell 21 via the bias resistor R3. Further, a first semiconductor switch 27 formed of a p-channel MOSFET is connected between both ends of the solar cell 21, and a second semiconductor switch formed of an n-channel MOSFET is connected between the solar cell 21 and the first semiconductor switch 27. 28 is inserted. Further, the p-channel M which is the first semiconductor switch is provided between the gate and the source of the n-channel MOSFET which is the above-mentioned semiconductor switching element 22.
It is connected between the source and drain of the OSFET.

By the way, the first semiconductor switch 27 and the second semiconductor switch 28 are complementarily turned on and off by conduction and non-conduction of the photodiode 25, and the first semiconductor switch 27 and the second semiconductor switch 28 are turned on and off while the second light emitting element 11b is lit. Semiconductor switch 2
7 is turned off, the second semiconductor switch 28 is turned on, and the first semiconductor switch 27 is turned on and the second semiconductor switch 28 is turned off while the second light emitting element 11b is turned off. The connection relationship between the semiconductor switches 27 and 28 and the photodiode 25 is set.

That is, in the present embodiment, the drains and gates of the p-channel MOSFET that is the first semiconductor switch 27 and the n-channel MOSFET that is the second semiconductor switch element 28 are commonly connected, and the solar cell 21 is connected. The first semiconductor switch 2 to the positive terminal of the
7 is connected to the source of the p-channel MOSFET and the source of the n-channel MOSFET that is the second semiconductor switching element 28 is connected to the negative terminal of the solar cell 21, and the commonly connected gate is the photodiode 2
5 is connected to the anode.

The operation of the drive circuit of this embodiment will be described below.

First, the operation when the semiconductor switch element 22 shifts from the off state to the on state will be described.

In the drive circuit of this embodiment, since the first light emitting element 11a is constantly turned on (continuously turned on) by the DC power supply 12a, the voltage across the solar cell 21 can always turn on the semiconductor switch element 22. The voltage is about the same as that. In this state, the pulse power source 12b
When a pulse voltage is output from the second light emitting element 11b
Lights up, the photodiode 25 becomes conductive, and the p-channel MOSFET that is the first semiconductor switch 27 is turned on.
And an n-channel MOSF which is the second semiconductor switch 28.
A voltage is applied to the gate of each ET.
Therefore, the second semiconductor switch 28 is turned on and the first semiconductor switch 27 is turned off, so that the output of the solar cell 21 is output between the gate and the source (between the control input terminals) of the n-channel MOSFET that is the semiconductor switch element 22. A voltage will be applied. Here, as described above, the voltage across the solar cell 21 is always the semiconductor switching element 22.
Since the voltage is set to a level that enables the semiconductor switch element 2 to be turned on, it is not necessary to charge the solar cell 21 when the semiconductor switch element 22 is turned on as in the conventional case.
The gate-source of the n-channel MOSFET 22, which is 2, can be charged faster than in the conventional case, and can be turned on faster.

Next, the operation when the n-channel MOSFET constituting the semiconductor switch element 22 shifts from the on state to the off state will be described.

Since the first light emitting element 11a is constantly turned on (continuously turned on) by the DC power source 12a, the voltage across the solar cell 21 is always a voltage with which the semiconductor switch element 22 can be turned on. ing. In this state, when the output voltage of the pulse power supply 12b becomes 0V, the second light emitting element 11b is turned off, the photodiode 25 becomes non-conductive, and the first semiconductor switch 27, p.
The gate voltage of each of the channel MOSFET and the n-channel MOSFET that is the second semiconductor switch 28 is 0V.
become. Therefore, since the second semiconductor switch 28 is turned off and the first semiconductor switch 27 is turned on, the power from the solar cell 21 to the gate-source of the n-channel MOSFET that is the semiconductor switch element 22 is the second semiconductor switch. 28, the charge accumulated between the gate and the source of the n-channel MOSFET, which is the semiconductor switch element 22, is rapidly discharged through the p-channel MOSFET, which is the first semiconductor switch 27. 22 can be turned off at high speed. Here, unlike the conventional case, it is not necessary to discharge the charge accumulated in the inter-terminal capacitance (parasitic capacitance) of the solar cell 21 when the semiconductor switching element 22 is turned off, and the gate of the n-channel MOSFET that is the semiconductor switching element 22 is not required to be discharged. The electric charge accumulated between the sources can be discharged faster than in the conventional case, and can be turned off faster.

Therefore, in this embodiment, the first semiconductor switch 2 is operated while the second light emitting element 11bn is lit.
7 is turned off, the second semiconductor switch 28 is turned on, and the first semiconductor switch 27 is turned on and the second semiconductor switch 28 is turned off while the second light emitting element 11b is turned off. The connection relationship between the semiconductor switches 27 and 28 and the photodiode 25 is set, and the solar cell 21 having a relatively large inter-terminal capacitance (parasitic capacitance) is optically coupled to the first light emitting element 11b that is continuously lit. So
The solar cell 21 is always charged, and the first semiconductor switch 27 and the second semiconductor switch 27 that turn on and off complementarily
The control input to the semiconductor switch element 22 changes depending on each state of the semiconductor switch 28, and the solar cell 21 does not need to be charged and discharged as in the conventional case, so that the control input can be switched at high speed. The turn-on time and turn-off time of the switch element 22 can be shortened.

The second semiconductor switch 28 inserted between the solar cell 21 and the semiconductor switch element 22 is n.
Since the second semiconductor switch 28 is constituted by the channel MOSFET, the second semiconductor switch 28 is changed to the p-channel MOSFET.
On-resistance can be reduced without increasing the element area of the second semiconductor switch 28 occupying the semiconductor chip as compared with the case of configuring by T, which is advantageous for shortening the turn-on time and the same semiconductor chip. First
Semiconductor switch 27 and second semiconductor switch 28
The chip size can be reduced in the case of forming.

(Embodiment 2) The basic configuration of the drive circuit in this embodiment is substantially the same as that in Embodiment 1, and as shown in FIG. 2, the cathode of the photodiode 25 is connected to the solar cell 21 via the bias resistor R3. Connected to the positive electrode terminal of the solar cell 21 and the anode to the negative electrode terminal of the solar cell 21.
P-channel MOSFET which is the semiconductor switch 27 and n-channel MOS which is the second semiconductor switch 28
The difference is that each gate of the FET is connected to the cathode of the photodiode 25. That is, in the present embodiment, while the second light emitting element 11b is on, the first semiconductor switch 27 is on, the second semiconductor switch 28 is off, and the second light emitting element 11b is off. While the first semiconductor switch 27 is turned on, the first semiconductor switch 27 is turned off and the second semiconductor switch 28 is turned on.
And the connection relationship between the photodiode 25 and the photodiode 25 are set. Since other configurations are similar to those of the first embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Therefore, in the drive circuit of this embodiment, the first semiconductor switch 27 is turned on and the second semiconductor switch 28 is turned off while the second light emitting element 11b is lit, and the second semiconductor switch 28 is turned off. While the light emitting element 11b is off, the first semiconductor switch 27 is turned off and the second semiconductor switch 28 is turned on.
Since the connection relationship between the photodiode and the photodiode 25 is set, the solar cell 21 having a relatively large inter-terminal capacitance (parasitic capacitance) is optically coupled to the first light emitting element 11b that is continuously lit. 21 is always charged, and the control input to the semiconductor switch element 22 changes depending on the states of the first semiconductor switch 27 and the second semiconductor switch 28 that are turned on and off complementarily. Since it is not necessary to charge and discharge the solar cell 21 like the above, the control input can be switched at high speed,
The turn-on time and turn-off time of the semiconductor switch element 22 can be shortened.

Further, as in the first embodiment, the solar cell 21
Since the second semiconductor switch 28 inserted between the semiconductor switch element 22 and the semiconductor switch element 22 is composed of an n-channel MOSFET,
On-resistance can be reduced without increasing the element area of the second semiconductor switch 28 occupying the semiconductor chip, as compared with the case where the channel MOSFET is used.
This is advantageous in shortening the turn-on time, and the chip size can be reduced when the first semiconductor switch 27 and the second semiconductor switch 28 are formed on the same semiconductor chip.

Further, in this embodiment, the pulse power source 12b is used.
When the second light emitting element 11b is turned off due to the output voltage of 0V, the photodiode 25 becomes non-conductive,
The p-channel MOSFE which is the first semiconductor switch 27
T is turned off, the n-channel MOSFET that is the second semiconductor switch 28 is turned on, and the semiconductor switch element 22
Since the gate-source of the n-channel MOSFET, which is the above, is charged and the semiconductor switch element 22 is turned on, the semiconductor switch element 22 is turned off by setting the output voltage of the pulse power supply 12b to 0V and turning off the second light emitting element 11b.
Can be turned on, and there is an advantage that power saving can be achieved.

(Third Embodiment) The basic configuration of the drive circuit in this embodiment is substantially the same as that of the second embodiment, and as shown in FIG. 3, the first semiconductor switch 27 is an n-channel MO.
The difference is that it is composed of an SFET and the second semiconductor switch 28 is composed of a p-channel MOSFET inserted between the positive terminal of the solar cell 21 and the first semiconductor switch 27. Here, the n-channel MOSFET that constitutes the first semiconductor switch 27 is connected between the drain and the source and between the gate and the source of the n-channel MOSFET that is the semiconductor switch element 22. The drain of the p-channel MOSFET forming the second semiconductor switch 28 has the first semiconductor switch 2
7 is connected to the drain of the n-channel MOSFET and the source is connected to the positive terminal of the solar cell 21. Other configurations are similar to those of the second embodiment, and therefore, the second embodiment
The same components as those of the above are denoted by the same reference numerals and the description thereof will be omitted.

In the drive circuit of this embodiment, however, as in the case of the second embodiment, the solar cell 21 is always charged, and the first semiconductor switch 27 and the second semiconductor switch 27 which are turned on and off complementarily are provided. The control input to the semiconductor switch element 22 changes depending on each state of the semiconductor switch 28, and the solar cell 21 does not need to be charged and discharged as in the conventional case, so that the control input can be switched at high speed. The turn-on time and turn-off time of the switch element 22 can be shortened. Note that in the present embodiment, as in the case of the first embodiment, the first semiconductor switch 27 is turned off and the second semiconductor switch 28 is turned on while the second light emitting element 11b is lit, and the second semiconductor switch 28 is turned on. Light emitting element 11
The connection relationship between the semiconductor switches 27 and 28 and the photodiode 25 is set so that the first semiconductor switch 27 is turned on and the second semiconductor switch 28 is turned off while b is off.

Further, in the drive circuit of this embodiment, the first semiconductor switch 27 connected between both ends of the solar cell 21.
Is composed of an n-channel MOSFET, the first semiconductor switch 27 is a p-channel MOS.
The ON resistance can be reduced without increasing the element area of the first semiconductor switch 27 occupying the semiconductor chip as compared with the case where the FET is used, which is advantageous in shortening the turn-off time.

(Embodiment 4) The basic structure of the drive circuit in this embodiment is substantially the same as that of the third embodiment. As shown in FIG. 4, the cathode of the photodiode 25 is connected to the positive terminal of the solar cell 21. At the same time, the anode of the photodiode 25 is connected to the negative terminal of the solar cell 21 via the bias resistor R3, and the semiconductor switches 27, 2
The difference is that the gate of 8 is connected to the anode of the photodiode 27. Since other configurations are the same as those of the third embodiment, the same components as those of the third embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the drive circuit of this embodiment, however, as in the case of the third embodiment, the solar cell 21 is always charged, and the first semiconductor switch 27 and the second semiconductor switch 27 that are turned on and off complementarily are turned on and off. The control input to the semiconductor switch element 22 changes depending on each state of the semiconductor switch 28, and the solar cell 21 does not need to be charged and discharged as in the conventional case, so that the control input can be switched at high speed. The turn-on time and turn-off time of the switch element 22 can be shortened. Further, as in the case of the third embodiment, when the first semiconductor switch 27 connected between both ends of the solar cell 21 is composed of an n-channel MOSFET, the first semiconductor switch 27 is composed of a p-channel MOSFET. On the other hand, the ON resistance can be reduced without increasing the element area of the first semiconductor switch 27 occupied in the semiconductor chip, which is advantageous in shortening the turn-off time.

Further, in the present embodiment, as in the second embodiment, the first semiconductor switch 27 is turned on and the second semiconductor switch 28 is turned on while the second light emitting element 11b is lit.
Is turned off and the first semiconductor switch 27 is turned off and the second semiconductor switch 28 is turned on while the second light emitting element 11b is turned off.
8 is connected to the photodiode 25, and when the output voltage of the pulse power supply 12b becomes 0V and the second light emitting element 11b is turned off, the photodiode 25
Becomes non-conductive, the n-channel MOSFET that is the first semiconductor switch 27 is turned off, the p-channel MOSFET that is the second semiconductor switch 28 is turned on, and the gate of the n-channel MOSFET that is the semiconductor switch element 22 is turned on. The semiconductor switch element 22 is charged between the sources.
Is turned on, the output voltage of the pulse power supply 12b is 0V.
As a result, it is possible to turn on the semiconductor switch element 22 by turning off the second light emitting element 11b, and there is an advantage that power saving can be achieved.

(Embodiment 5) In this embodiment, a semiconductor relay having the drive circuit of Embodiment 3 and having the structure shown in FIG. 5 is exemplified. In the present embodiment, the semiconductor switch element 22 configured by one n-channel MOSFET in the third embodiment has two n-channel MOSFEs whose gates and sources are commonly connected.
It is composed of T22a and T22b. In the present embodiment, the drains of the n-channel MOSFETs 22a and 22b form main terminals and are connected to the output terminals (relay output terminals) 26a and 26b, respectively. The n-channel MOS of each n-channel MOS
A gate voltage (gate-source voltage) applied between the gates and sources of the FETs 22a and 22b serves as a control input.

Therefore, in the semiconductor relay of this embodiment, for example, a series circuit of a load and an AC power source can be connected and used between the output terminals 26a and 26b connected to the main terminal of the semiconductor switch element 22, The semiconductor switch element 22 can be turned on and off at high speed.

In the present embodiment, the case where the drive circuit of the third embodiment is used as the drive circuit has been exemplified.
It goes without saying that the drive circuits of other embodiments may be used.

By the way, in each of the above embodiments, one or two n-channel MOSF semiconductor switch elements 22 are provided.
Although the example configured by the ET has been described, it is not limited to the n-channel MOSFET, but the p-channel MOSFET, the IG
You may comprise by other semiconductor elements, such as BT.

[0050]

According to a first aspect of the present invention, there is provided a drive circuit for a semiconductor switch element which is turned on / off according to a control input applied between control input terminals, wherein the first light emitting element and the first light emitting element are provided. A solar cell that is optically coupled and can provide a control input for turning on the semiconductor switch element between the control input terminals; a second light emitting element; a photodiode optically coupled to the second light emitting element; A first semiconductor switch connected between both ends of the battery and turned on / off by conduction / non-conduction of the photodiode, and a first semiconductor switch inserted between the solar cell and the first semiconductor switch by conduction / non-conduction of the photodiode. A second semiconductor switch that is turned on / off complementarily to the semiconductor switch, a first driving unit that continuously turns on the first light emitting element, and a second drive that intermittently turns on the second light emitting element. And drive means, while the second light-emitting element is lit first semiconductor switch is turned off, the second
Of the semiconductor switch is turned on, and while the second light emitting element is turned off, the first semiconductor switch is turned on and the second semiconductor switch is turned off. Since the solar cell having a relatively large inter-terminal capacity is optically coupled to the first light emitting element that is continuously lit, the solar cell is always charged and the complementary The control input between the control input terminals of the semiconductor switch element changes depending on the respective states of the first semiconductor switch and the second semiconductor switch that are turned on and off, thus eliminating the need for charging and discharging the solar cell as in the conventional case. Therefore, the control input can be switched at high speed, and the turn-on time and turn-off time of the semiconductor switch element can be shortened.

According to a second aspect of the invention, in the first aspect of the invention, the cathode of the photodiode is connected to the positive terminal of the solar cell and the anode is connected to the negative terminal of the solar cell through a bias resistor. The first semiconductor switch is composed of a p-channel MOSFET, and the second semiconductor switch is an n-channel MOS.
The drain terminal and the gate terminal of the p-channel MOSFET and the n-channel MOSFET are commonly connected to each other, and the source terminal of the p-channel MOSFET is connected to the positive terminal of the solar cell. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell and the commonly connected gate terminal is connected to the anode of the photodiode, it is inserted between the solar cell and the semiconductor switch element. Since the second semiconductor switch is composed of an n-channel MOSFET, the second semiconductor switch is connected to the p-channel M-channel.
On-resistance can be reduced without increasing the element area of the second semiconductor switch occupying the semiconductor chip as compared with the case where it is configured by the OSFET, which is advantageous in shortening the turn-on time.

According to a third aspect of the invention, in the first aspect of the invention, the cathode of the photodiode is connected to the positive terminal of the solar cell through a bias resistor and the anode is connected to the negative terminal of the solar cell. The first semiconductor switch is composed of an n-channel MOSFET and the second semiconductor switch is a p-channel MOS.
The drain terminal and the gate terminal of the n-channel MOSFET and the p-channel MOSFET are commonly connected to each other, and the positive terminal of the solar cell is connected to the source terminal of the p-channel MOSFET. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the cathode of the photodiode, the first terminal connected between both ends of the solar cell. Semiconductor switch is n-channel MOS
Since it is configured by the FET, it is possible to reduce the on-resistance without increasing the element area of the first semiconductor switch occupying the semiconductor chip as compared with the case where the first semiconductor switch is configured by the p-channel MOSFET. This is advantageous in shortening the turn-off time.

According to a fourth aspect of the present invention, there is provided a drive circuit for a semiconductor switch element which is turned on / off according to a control input applied between control input terminals, wherein the first light emitting element and the first light emitting element are optically coupled. A solar cell capable of providing a control input for turning on the semiconductor switch element between the control input terminals; a second light emitting element; a photodiode optically coupled to the second light emitting element; A first semiconductor switch connected between both ends and turned on / off by conduction / non-conduction of the photodiode, and a first semiconductor switch inserted between the solar cell and the first semiconductor switch by conduction / non-conduction of the photodiode A second semiconductor switch that is turned on and off complementarily to the first light emitting element, a first driving unit that continuously lights the first light emitting element, and a second light emitting element that intermittently lights the second light emitting element. The first semiconductor switch is on while the second light emitting element is on, the second semiconductor switch is off, and the first semiconductor switch is off while the second light emitting element is off. The semiconductor switch is turned off and the second semiconductor switch is turned on so that the connection relationship between each semiconductor switch and the photodiode is set.
Since the solar cell having a relatively large inter-terminal capacity is optically coupled to the first light-emitting element that continuously lights up, the solar cell is always in a charged state, and the first semiconductor switch is turned on / off complementarily. The control input to the semiconductor switch element changes depending on the respective states of the second semiconductor switch and the second semiconductor switch, and it is not necessary to charge and discharge the solar cell as in the conventional case. Therefore, the control input can be switched at high speed. There is an effect that the turn-on time and the turn-off time of the switch element can be shortened.

According to a fifth aspect of the invention, in the fourth aspect, the cathode of the photodiode is connected to the positive terminal of the solar cell through a bias resistor and the anode is connected to the negative terminal of the solar cell. The first semiconductor switch is composed of a p-channel MOSFET, and the second semiconductor switch is an n-channel MOS.
The drain terminal and the gate terminal of the p-channel MOSFET and the n-channel MOSFET are commonly connected to each other, and the source terminal of the p-channel MOSFET is connected to the positive terminal of the solar cell. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell and the commonly connected gate terminal is connected to the cathode of the photodiode, it is inserted between the solar cell and the semiconductor switch element. Since the second semiconductor switch is composed of an n-channel MOSFET, the second semiconductor switch is connected to the p-channel M-channel.
On-resistance can be reduced without increasing the element area of the second semiconductor switch occupying the semiconductor chip as compared with the case where it is configured by the OSFET, which is advantageous in shortening the turn-on time. Further, since the photodiode becomes non-conductive when the second light emitting element is off, the p-channel MOSFET that is the first semiconductor switch is turned off, and the second semiconductor switch is turned off.
Since the n-channel MOSFET that is the semiconductor switch is turned on, there is an advantage that the semiconductor switch element can be turned on by turning off the second light emitting element.

According to a sixth aspect of the invention, in the fourth aspect of the invention, the cathode of the photodiode is connected to the positive terminal of the solar cell and the anode is connected to the negative terminal of the solar cell through a bias resistor. The first semiconductor switch is composed of an n-channel MOSFET and the second semiconductor switch is a p-channel MOS.
The drain terminal and the gate terminal of the n-channel MOSFET and the p-channel MOSFET are commonly connected to each other, and the positive terminal of the solar cell is connected to the source terminal of the p-channel MOSFET. Since the source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the anode of the photodiode, the first terminal connected between both ends of the solar cell. Semiconductor switch is n-channel MOS
Since it is configured by the FET, it is possible to reduce the on-resistance without increasing the element area of the first semiconductor switch occupying the semiconductor chip as compared with the case where the first semiconductor switch is configured by the p-channel MOSFET. This is advantageous in shortening the turn-off time. Further, since the photodiode becomes non-conductive when the second light emitting element is off, the p-channel MOSFET that is the first semiconductor switch is off and the n-channel MOSFET that is the second semiconductor switch. Is turned on, there is an advantage that the semiconductor switch element can be turned on by turning off the second light emitting element.

According to a seventh aspect of the present invention, there is provided a semiconductor switch element drive circuit according to any one of the first to sixth aspects and the semiconductor switch element, wherein the semiconductor switch element has two electric fields. A control input terminal is provided between a connection point between the gate terminals of the effect transistor and a connection point between the source terminals thereof, and each drain terminal is configured as a main terminal, and the first semiconductor switch is connected between the control input terminals. In addition, the solar cell is connected via a second semiconductor switch, and for example, a series circuit of a load and an AC power source is connected between the main terminals of the semiconductor switch element. Can be used as
There is an effect that the semiconductor switch element can be turned on and off at high speed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a circuit diagram showing a second embodiment.

FIG. 3 is a circuit diagram showing a third embodiment.

FIG. 4 is a circuit diagram showing a fourth embodiment.

FIG. 5 is a circuit diagram showing a fifth embodiment.

FIG. 6 is a circuit diagram showing a conventional example.

[Explanation of symbols]

11a First light emitting element 11b Second light emitting element 12a DC power supply 12b pulse power supply 21 solar cells 22 Semiconductor switch element 25 photodiode 26a, 26b output terminals 27 First semiconductor switch 28 Second semiconductor switch R3 bias resistance

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5J050 AA02 BB21 CC02 DD03 DD06                       EE17 FF04 FF10                 5J055 AX03 AX04 AX55 AX56 BX48                       CX01 CX08 CX18 DX13 DX22                       DX83 EX07 EY01 EY14 FX12                       FX32 GX01

Claims (7)

[Claims] 1. A drive circuit for a semiconductor switch element, which is turned on / off in response to a control input applied between control input terminals, wherein the first light emitting element and the control input terminal are optically coupled to the first light emitting element. A solar cell capable of providing a control input for turning on the semiconductor switch element, a second light emitting element, a photodiode optically coupled to the second light emitting element, and a solar cell connected between both ends of the solar cell. A first semiconductor switch, which is turned on / off by conduction / non-conduction of the photodiode, and a first semiconductor switch, which is inserted between the solar cell and the first semiconductor switch, is complementarily turned on / off by conduction / non-conduction of the photodiode. A second semiconductor switch, a first driving means for continuously lighting the first light emitting element, and a second driving means for intermittently lighting the second light emitting element, While the second light emitting element is on, the first semiconductor switch is off, the second semiconductor switch is on, and while the second light emitting element is off, the first semiconductor switch is on, A drive circuit for a semiconductor switch element, wherein a connection relationship between each semiconductor switch and a photodiode is set so that the second semiconductor switch is turned off. 2. The cathode of the photodiode is connected to the positive terminal of the solar cell, the anode is connected to the negative terminal of the solar cell via a bias resistor, and the first semiconductor switch is a p-channel MOSFET. And the second semiconductor switch is composed of an n-channel MOSFET, and the p-channel MO
Drain terminals and gate terminals of the SFET and the n-channel MOSFET are commonly connected,
The p-channel MOSFET is connected to the positive terminal of the solar cell.
The source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the anode of the photodiode. Item 2. A drive circuit for a semiconductor switch element according to Item 1. 3. The cathode of the photodiode is connected to the positive terminal of the solar cell via a bias resistor, the anode is connected to the negative terminal of the solar cell, and the first semiconductor switch is an n-channel MOSFET. And the second semiconductor switch is composed of a p-channel MOSFET, and the n-channel MO
Drain terminals and gate terminals of the SFET and the p-channel MOSFET are commonly connected,
The p-channel MOSFET is connected to the positive terminal of the solar cell.
The source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the cathode of the photodiode. Item 2. A drive circuit for a semiconductor switch element according to Item 1. 4. A drive circuit for a semiconductor switch element, which is turned on / off according to a control input applied between control input terminals, wherein the first light emitting element and the first light emitting element are optically coupled to the control input terminal. A solar cell capable of providing a control input for turning on the semiconductor switch element, a second light emitting element, a photodiode optically coupled to the second light emitting element, and a solar cell connected between both ends of the solar cell. A first semiconductor switch, which is turned on / off by conduction / non-conduction of the photodiode, and a first semiconductor switch, which is inserted between the solar cell and the first semiconductor switch, is complementarily turned on / off by conduction / non-conduction of the photodiode. A second semiconductor switch, a first driving means for continuously lighting the first light emitting element, and a second driving means for intermittently lighting the second light emitting element, While the second light emitting element is lit, the first semiconductor switch is on, the second semiconductor switch is off, and while the second light emitting element is off, the first semiconductor switch is off, A drive circuit for a semiconductor switch element, wherein the connection relationship between each semiconductor switch and a photodiode is set so that the second semiconductor switch is turned on. 5. The cathode of the photodiode is connected to a positive terminal of the solar cell via a bias resistor and the anode is connected to a negative terminal of the solar cell, and the first semiconductor switch is a p-channel MOSFET. And the second semiconductor switch is composed of an n-channel MOSFET, and the p-channel MO
Drain terminals and gate terminals of the SFET and the n-channel MOSFET are commonly connected,
The p-channel MOSFET is connected to the positive terminal of the solar cell.
The source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the cathode of the photodiode. Item 4. A drive circuit for a semiconductor switch element according to Item 4. 6. The cathode of the photodiode is connected to the positive terminal of the solar cell, the anode is connected to the negative terminal of the solar cell via a bias resistor, and the first semiconductor switch is an n-channel MOSFET. And the second semiconductor switch is composed of a p-channel MOSFET, and the n-channel MO
Drain terminals and gate terminals of the SFET and the p-channel MOSFET are commonly connected,
The p-channel MOSFET is connected to the positive terminal of the solar cell.
The source terminal of the n-channel MOSFET is connected to the negative terminal of the solar cell, and the commonly connected gate terminal is connected to the anode of the photodiode. Item 4. A drive circuit for a semiconductor switch element according to Item 4. 7. A semiconductor switch element drive circuit according to claim 1, and the semiconductor switch element, wherein the semiconductor switch element is 2
The first semiconductor switch is configured such that a control input terminal is formed between a connection point between the gate terminals of the two field effect transistors and a connection point between the source terminals thereof, and each drain terminal is formed as a main terminal. And the solar cell is connected via a second semiconductor switch.