JP2001313555A - Semiconductor relay and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change an output MOSFET into a conductive state at higher speed. SOLUTION: The semiconductor relay of this invention is provided with a light emitting element 1 that emits an optical signal in response to an input signal, a light receiving element 2 that generates a photovoltaic force on the basis of the optical signal from the light emitting element 1, an output MOSFET 3 whose drain and source are connected in series with a power supply 50, whose gate and source are connected to the light receiving element 2, and that is driven when electric charges are charged to the gate, a control circuit 60 that controls charging/discharging of gate charges of the output MOSFET 3, an advanced conduction TR 6 that is connected in parallel between the drain and the source of the output MOSFET 3, driven earlier than the output MOSFET 3 when receiving the photovoltaic force by the light receiving element 2, and conductive, and a current supply TR 9 that is driven by a current supplied from the power supply 50 through the conduction of the advanced conduction TR 6 and supplies a current from the power supply 50 to the gate of the output MOSFET 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed turn-on type semiconductor relay.

[0002]

2. Description of the Related Art Conventionally, as this kind of semiconductor relay, there is one shown in FIGS. This device includes a light emitting diode (light emitting element) 101, a photodiode array (light receiving element) 102, an enhancement type output MOSF.
ET103, control resistor 104, depletion-type control MOSFET 105, phototransistor 10
6. It includes the diode 107.

Next, the operation will be described. When an input signal is input between both input terminals X1, the light emitting diode 101 emits an optical signal. This optical signal is received by the photodiode array 102 and the phototransistor 106.

The phototransistor 106 is turned on by receiving an optical signal emitted by the light emitting diode 101, and a current from a power supply E connected between both output terminals X2 flows through the diode. As a result, in the output MOSFET 103, a current flows from the power supply E to the gate, the gate-source is charged, and the output MOSFET 103 is charged.
The state between the drain and source of the FET 103 changes from the cutoff state to the conduction state at a high speed.

On the other hand, the photodiode array 102
By receiving an optical signal emitted by the light emitting diode 101, a photoelectromotive force is generated. This photovoltaic voltage is applied between the gate and the source of the output MOSFET 103, and charges between the gate and the source of the output MOSFET 103. The current that charges between the gate and the source of the output MOSFET 103 flows between the drain and the source of the control MOSFET 105. It flows through the control resistor 104. Since a voltage is generated at both ends of the control resistor 104, the control MOS
In the FET 105, the gate has a negative bias voltage with respect to the source, and the state between the drain and the source changes from the conductive state to the cutoff state. As a result, the output MOSFE
Between the gate and the source of T103, charging is continued efficiently, the conduction state is maintained, and stable operation is performed irrespective of the voltage and current of the power supply E.

If an input signal is not input between the two input terminals X1, the light emitting element 101 does not emit a light signal, and the photodiode array 102 does not generate photovoltaic power. The negative bias voltage that cuts off between the drain and source of the control MOSFET 105 disappears, and the drain and source of the control MOSFET 105 returns from the cut-off state to the conductive state.

In the output main MOSFET 103, the electric charge charged between the gate and the source is changed to the control MOSFET 1
The output MOS is discharged through the drain source
The state between the drain and source of the FET 103 changes from the conductive state to the cutoff state.

[0008]

In the above-described conventional semiconductor relay, the light signal emitted from the light emitting diode 101 is distributed to the photodiode array 102 and the phototransistor 106, and the phototransistor 106 is turned on early. As a result, the output MOSFET 10
3 at a high speed, an electromotive force is generated in the photodiode array 102, and the electromotive force is applied to the output MOSFET 103, so that the power is stable regardless of the voltage and current of the power source E. It works.

For this purpose, as shown in FIG. 5, an input side lead frame 200 supported in a package 200a is provided.
b, the light emitting diode 101 is provided, and the photodiode array 102 and the phototransistor 106 are mounted on the output side lead frame 200c supported in the package 200a so as to face the input side lead frame 200b.
Is provided, in order to change the output MOSFET 103 to the conducting state more rapidly, the light emitting diode 10 is used.
1 emits an optical signal to the photodiode array 102
In addition, the optimal arrangement of the photodiode array 102 and the phototransistor 106 provided on the output side lead frame 200c is designed so as to be appropriately distributed to the phototransistor 106.

However, the output side lead frame 20
0c, the output M
There is a limit to changing the OSFET 103 to the conductive state more quickly.

The present invention has been made in view of the above points, and an object of the present invention is to provide a semiconductor relay capable of changing an output MOSFET to a conductive state more quickly.

[0012]

According to a first aspect of the present invention, there is provided a semiconductor relay which emits an optical signal in response to an input signal, and a light emitting element which emits an optical signal based on the optical signal of the light emitting element. A light-receiving element that generates an electromotive force, an output MOSFET that is connected in series with a power supply between the drain and source, is connected to the light-receiving element between the gate and source so that the photoelectromotive force is applied, and is driven when the gate is charged with electric charge. A control circuit for controlling the charging and discharging of the gate charge of the output MOSFET, and a photoconductive element connected in parallel between the drain and the source of the output MOSFET. And a current from the power supply is driven by the current flowing from the power supply when the preceding conduction transistor is turned on. It is configured to include a current supply transistor to the gate of the MOSFET.

According to a second aspect of the present invention, there is provided a semiconductor relay according to the first aspect.
In the semiconductor relay described above, the preceding conduction transistor is configured to be a MOSFET.

According to a third aspect of the present invention, in the semiconductor relay, a driving resistor for generating a voltage difference for driving the current supply transistor when the current flows between both ends is provided, and the driving resistor is provided through the driving resistor. A leading conduction transistor is connected in parallel between the drain and the source of the output MOSFET, and the impedance of the driving resistor is adjusted by the output MO.
The configuration is such that the impedance is higher than when the SFET is driven and turned on.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor relay, comprising: a light emitting element that emits an optical signal in response to an input signal; a light receiving element that generates a photoelectromotive force based on the optical signal of the light emitting element; Are connected in series to a power supply, and between the gate and the source are connected to a light receiving element so that a photovoltaic voltage is applied.
An OSFET, a control circuit for controlling the charge and discharge of the gate charge of the output MOSFET, and a drive circuit which is connected in parallel between the drain and source of the output MOSFET and which is driven before the output MOSFET when a photoelectromotive force is applied by the light receiving element. And a current supply transistor which is driven by a current flowing from the power supply when the preceding conduction transistor is turned on to supply a current from the power supply to a gate of the output MOSFET. A method for manufacturing a semiconductor relay for manufacturing a relay, wherein the preceding conduction transistor and the current supply transistor are provided in the same step as the control circuit.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a semiconductor relay, comprising: a light emitting element for emitting an optical signal in response to an input signal; a light receiving element for generating a photovoltaic power based on the optical signal of the light emitting element; Are connected in series to a power supply, and between the gate and the source are connected to a light receiving element so that a photovoltaic voltage is applied.
An OSFET, a control circuit for controlling the charge and discharge of the gate charge of the output MOSFET, and a drive circuit which is connected in parallel between the drain and source of the output MOSFET and which is driven before the output MOSFET when a photoelectromotive force is applied by the light receiving element. And a current supply transistor that is driven by a current flowing from the power supply to supply a current from the power supply to the gate of the output MOSFET and that is connected between both ends. A driving resistor for generating a voltage difference for driving the current supply transistor by flowing a current, the method comprising: a. Transistor and the driving resistor are provided in the same step as the control circuit. Unishi to have.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor relay according to an embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a light emitting diode (light emitting element) which emits an optical signal according to an input signal inputted between the input terminals 20a and 20b. FIG.
As shown in FIG. 2, the input side frame 30b is provided in the package 30a.

2 is a photodiode array (light receiving element)
Thus, a plurality of photodiodes 2a are connected in series to receive an optical signal from the light emitting diode 1 and generate a photoelectromotive force. The photodiode array 2 is provided on an output side frame 30c supported opposite to an input side frame 30b supported inside a package 30a. The photodiode array 2 and the light emitting diode 1 are surrounded by a transparent resin 30d, and a sealing resin 30e is sealed between the transparent resin 30d and the inner surface of the package 30a.

Reference numeral 3 denotes an output MOSFET 3 in an enhancement mode, the gate of which is connected to the anode of the photodiode array 2 and the drain of which is the output terminal 2.
0c, the source is connected to the cathode of the photodiode array 2 via the control resistor 4 described later, and is connected to the output terminal 20d. The load 40 and the power supply 5 are connected between these output terminals 20c and 20d.
0 is connected in series.

Reference numeral 4 denotes a control resistor, one end of which is connected to the cathode of the photodiode array 2 and a control MOSFET to be described later.
Connected to the gate of ET5, the other end is a control MOSFET
5 and the source of the output MOSFET 3.

Reference numeral 5 denotes a control MOSFET, which is a depletion mode. As described above, the control resistor 4 is connected between its gate and source, and its drain is connected to the anode of the photodiode array 2 and the gate of the output MOSFET 3. Have been. This control MOSFET 5
Constitutes, together with the control resistor 4, a control circuit 60 that controls charging and discharging of a charge (gate charge) between the gate and the source of the output MOSFET 3.

Reference numeral 6 denotes a preceding conduction MOSFET (preceding conduction transistor), which is in an enhancement mode, has a gate capacitance smaller than that of the output MOSFET 3, and its drain has a driving resistor 7 and a connection resistor 8 described later and a diode 10 described later. Through the output MOSFET 3
And the source is connected to the output MO.
The source is connected to the source of the SFET 3, and the gate is connected to the gate of the output MOSFET 3, thereby being connected in parallel to the output MOSFET 3.

Further, like the output MOSFET 3, the gate of the preceding conduction MOSFET 6 is connected to the anode of the photodiode array 2, and the source is connected to the cathode of the photodiode array 2 via the control resistor 4. Further, the drain is connected to the output terminal 20c and the source is connected to the output terminal 20d via the driving resistor 7, the connecting resistor 8 connected in series to the driving resistor 7, and the diode 10. I have.

The driving resistor 7 together with the connection resistor 8 is larger than the resistance between the drain and source of the output MOSFET 3 when conducting. The drive resistor 7 is provided in the same step as the control circuit 60 described above, together with the connection resistor 8, the preceding conduction MOSFET 6, and the current supply MOSFET 9 described later.

Reference numeral 9 denotes a current supply MOSFET (current supply transistor) in an enhancement mode.
The source is an output MOSFET through a diode 10.
The drain is connected to the drain of T3, the drain is connected to the gate of the output MOSFET 3, and the gate is connected to the connection point between the driving resistor 7 and the connecting resistor 8, so that the driving resistor 7 is connected. Connected to source.

Reference numeral 10 denotes a diode whose anode is connected to the drain of the output MOSFET 3 and whose cathode is connected to the source of the current supply MOSFET 9 so that the forward direction is the same as the direction in which the current flows from the power supply. Has become.

Next, the operation will be described. Both input terminals 20
When an input signal is input between a and 20b, the light emitting diode 1 emits an optical signal. This optical signal is received by the photodiode array 2. Photodiode array 2
Generates a photoelectromotive force by receiving an optical signal emitted by the light emitting diode 1. This photoelectromotive force is generated between the gate and the source of the output MOSFET 3 and the preceding conduction MOSFET.
Applied between the gate and source of ET6.

Since the leading conductive MOSFET 6 has a smaller gate capacitance than the output MOSFET 3 as described above, when a photovoltaic voltage is applied between the gate and the source under the same conditions as the output MOSFET 3, the output conductive MOSFET 6 has a smaller output capacitance. MO
It is driven before the SFET 3 and becomes conductive.

Then, a current from the power supply 50 flows in the forward direction of the diode 10 in the order of the driving resistor 7, the connecting resistor 8, and the preceding conductive MOSFET 6, and as a result, the driving resistor 7 and the connecting resistor 8 Connection point, that is, the potential of the gate of the current supply MOSFET 9 is
It drops below the source potential of SFET 9. In this way, when the potential of the gate becomes lower than the potential of the source, the current supply MOSFET 9 is driven to conduct.

When the current supply MOSFET 9 is turned on, the output MOSFET 3 is supplied with a current from the power supply 50 to the gate through the current supply MOSFET 9, and is charged and driven between the gate and the source.
As shown by the solid line in FIG.
, The drain-source state changes from the cutoff state to the conduction state at high speed.

As described above, the output MOSFET 3 is charged between the gate and the source by the photoelectromotive force of the photodiode array 2 being applied between the gate and the source. Based on the photoelectromotive force of the photodiode array 2, a current for charging the gate and source of the output MOSFET 3 flows between the drain and source of the control MOSFET 5 via the control resistor 4.

Then, a voltage is generated at both ends of the control resistor 4, so that the gate of the control MOSFET 5 has a negative bias voltage with respect to the source, and the state between the drain and the source is changed from the conductive state to the cutoff state. Change. As a result, between the gate and the source of the output MOSFET 3 is continuously charged efficiently, the conduction state is maintained, and the operation is stabilized irrespective of the voltage and current of the power supply 50.

If an input signal is not input between the two input terminals 20a and 20b, the light emitting diode 1 does not emit a light signal, and the photodiode array 2 does not generate photovoltaic power. Current does not flow through the control resistor 4 and the bias voltage that has cut off the drain and source of the control MOSFET 5 disappears, so that the drain and source of the control MOSFET 5 return to the conductive state.

As a result, the electric charge charged between the gate and the source of the output MOSFET 3 becomes the control MOSFET.
5 is discharged through the drain source of the output M.
The OSFET 3 returns to the cutoff state between its drain and source.

In such a semiconductor relay, the application of the photovoltaic force by the photodiode array 2 causes the leading MOSFET M to be driven before the output MOSFET 3 is driven.
The current supply MOSFET driven by the conduction of the OSFET 6 and the conduction of the preceding conduction MOSFET 6
9 supplies the current from the power supply 50 to the gate of the output MOSFET 3, so that the output MOSFET 3 is driven at high speed.

Further, unlike the conventional example in which a phototransistor in which the light signal of the light emitting diode is distributed together with the photodiode array in order to drive the output MOSFET at a high speed, the light signal of the light emitting diode 1 is converted to the photodiode array. 2 can be focused on,
The output MOSFET 3 can be driven at a higher speed than the conventional example shown by the dashed line in FIG. 3, and the so-called turn-on time t from when the electromotive force is generated by the photodiode array 2 to when it is driven is reduced. Is shorter than the turn-on time T in the case of (1).

The preceding conduction transistor is a MOSF
ET, which is a transistor driven by a small photocurrent generated by application of an electromotive force generated by the photodiode array 2, has the effect of being driven at high speed and, consequently, of driving the output MOSFET 3. You can play more.

Further, since the impedance of the driving resistor 7 and the connection resistor 8 is larger than the impedance when the output MOSFET 3 is driven and turned on, the loss of the linearity of the output signal between the drain and the source between the output MOSFETs 3 is reduced. Can be reduced.

Since the leading conductive MOSFET 6, the current supplying MOSFET 9, and the connecting resistor 8 and the driving resistor 7 are provided in the same step as the control circuit 60, the leading conductive MOSFET 6, the current supplying MOSFET 9, and the connecting resistor 8 are connected. The step of providing the driving resistor 7 does not need to be separate from the step of providing the control circuit 60, which facilitates manufacturing.

In this embodiment, both the preceding conduction transistor and the current supply transistor are MOSFE
T is not limited to MOSFET, but may be, for example, a bipolar transistor.

[0042]

According to the first aspect of the present invention, an output MO is provided by applying a photoelectromotive force by a light receiving element.
Before the SFET is driven, the preceding conduction transistor conducts, and the current supply transistor driven by the conduction of the preceding conduction transistor supplies current from the power supply to the gate of the output MOSFET.
OSFET is driven at high speed, and output MOSF
Unlike the conventional example in which a phototransistor in which the light signal of the light emitting element is distributed together with the light receiving element in order to drive the ET at a high speed, the light signal of the light emitting element can be intensively irradiated to the light receiving element, The output MOSFET can be driven at a higher speed than in the conventional example.

In the semiconductor relay according to the second aspect, the preceding conduction transistor is a MOSFET, which is a transistor driven by a small photocurrent caused by application of an electromotive force by a light receiving element, and is therefore driven at a high speed. In addition, the effect of the semiconductor relay according to claim 1, which can drive the output MOSFET, can be further obtained.

The semiconductor relay according to the third aspect is the first aspect.
Or, in addition to the effect of the semiconductor relay according to claim 2, the impedance of the driving resistor is the output MOS.
Since the impedance is larger than the impedance when the FET is driven and turned on, the loss of the linearity of the output signal between the drain and the source between the output MOSFETs can be reduced.

According to the method for manufacturing a semiconductor relay according to the fourth aspect, since the preceding conduction transistor and the current supply transistor are provided in the same step as the control circuit, the step of providing the preceding conduction transistor and the current supply transistor is omitted.
The step of providing the control circuit does not need to be performed separately, and the manufacturing is facilitated.

According to the method of manufacturing a semiconductor relay of the present invention, since the preceding conduction transistor, the current supply transistor and the driving resistor are provided in the same step as the control circuit, the preceding conduction transistor, the current supply transistor and the driving transistor are provided. The step of providing the resistor does not need to be separate from the step of providing the control circuit, which facilitates manufacturing.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention.

FIG. 2 is a sectional view of the same.

FIG. 3 is an explanatory diagram showing a turn-on time of an output MOSFET.

FIG. 4 is a circuit diagram of a conventional example.

FIG. 5 is a sectional view of the same.

[Explanation of symbols]

Reference Signs List 1 light emitting diode (light emitting element) 2 photodiode array (light receiving element) 3 output MOSFET 6 preceding conduction MOSFET (preceding conduction transistor) 7 driving resistor 8 current supply MOSFET (current supply transistor) 50 power supply 60 control circuit

Claims (5)

[Claims] A light-emitting element that emits an optical signal in response to an input signal; a light-receiving element that generates a photovoltaic power based on the optical signal of the light-emitting element; An output MOSFET that is connected between a gate and a source so that power is applied to the light receiving element and is driven when the gate is charged, a control circuit that controls charging and discharging of the gate charge of the output MOSFET, and an output MOSFET
When a photovoltaic voltage is applied by a light receiving element and connected in parallel between the drain and source of T, a preceding conduction transistor which is driven prior to the output MOSFET and conducts, and which flows from the power supply when the preceding conduction transistor conducts An output MOS which is driven by a current and outputs the current from the power supply
A current supply transistor to be supplied to the gate of the FET;
A semiconductor relay comprising: 2. The method according to claim 1, wherein the preceding conduction transistor is a MOSF.
2. The semiconductor relay according to claim 1, wherein the semiconductor relay is ET. 3. A driving resistor for generating a voltage difference for driving the current supply transistor when the current flows between both ends, and the preceding conduction transistor is connected to the output transistor via the driving resistor. 3. The device according to claim 1, wherein the impedance of the driving resistor is connected in parallel between the drain and the source of the MOSFET, and is higher than the impedance when the output MOSFET is driven and turned on. Semiconductor relay. 4. A light-emitting element that emits an optical signal in response to an input signal, a light-receiving element that generates photovoltaic power based on an optical signal of the light-emitting element, An output MOSFET that is connected between a gate and a source so that power is applied to the light receiving element and is driven when the gate is charged, a control circuit that controls charging and discharging of the gate charge of the output MOSFET, and an output MOSFET
When a photovoltaic voltage is applied by a light receiving element and connected in parallel between the drain and source of T, a preceding conduction transistor which is driven prior to the output MOSFET and conducts, and which flows from the power supply when the preceding conduction transistor conducts An output MOS which is driven by a current and outputs the current from the power supply
A current supply transistor to be supplied to the gate of the FET;
A method for manufacturing a semiconductor relay, comprising: providing the preceding conduction transistor and the current supply transistor in the same step as the control circuit. 5. A light-emitting element that emits an optical signal in response to an input signal, a light-receiving element that generates photovoltaic power based on an optical signal of the light-emitting element, and a photovoltaic element that has a drain-source connected in series to a power supply. An output MOSFET that is connected between a gate and a source so that power is applied to the light receiving element and is driven when the gate is charged, a control circuit that controls charging and discharging of the gate charge of the output MOSFET, and an output MOSFET
When a photovoltaic voltage is applied by a light receiving element and connected in parallel between the drain and source of T, a preceding conduction transistor which is driven prior to the output MOSFET and conducts, and which flows from the power supply when the preceding conduction transistor conducts An output MOS which is driven by a current and outputs the current from the power supply
A current supply transistor to be supplied to the gate of the FET;
A driving resistor for generating a voltage difference for driving the current supply transistor by causing the current to flow between both ends, and a method for manufacturing a semiconductor relay including: And providing the current supply transistor and the driving resistor in the same step as the control circuit.