JPH0346410A - Semiconductor relay circuit - Google Patents

Abstract

PURPOSE:To obtain a semiconductor relay with an output switch of a high with stand voltage by combining N, P-channel enhancement MOSFETs symmetrically as the output switch. CONSTITUTION:When an input current flows between input terminals 1, 2, a light emitting diode D1 is lighted and the light radiates photovolatile diodes D2, D3, from which a photoelectric current is produced. The current charges a gate-source capacitance of N and P-channel enhancement MOSFETs Q1, Q2 turn on the MOSFETs. A current from an external load flows from a positive terminal 11 in this state, and flows out of a negative terminal 12. With the absence of the input, since the MOSFETs Q1, Q2 are turned off, and no current flows to the external load because of the block by the sum of drain- source breakdown voltages of the two MOSFETs. Thus, the with stand voltage of the output switch is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor relay circuit, and particularly to a connection structure for MOSFETs used as output switches.

[Conventional technology]

Conventionally, in this type of semiconductor relay circuit, when trying to increase the switching voltage, the switching element MOSFE
A T having a high breakdown voltage between the drain and source electrodes was used. , and as shown in the circuit diagram of FIG.
The source electrode S of the channel enhancement type MOSFET Q is commonly connected to the drain electrode of another MOSFET Qs, and the drain electrode of the MOSFET Qt is used as the positive output terminal 11.
The source electrode S of E T Q s is used as a negative switching terminal 12 . P) A method was used in which two MOSFETs Ql and Qs were connected in series to distribute the load voltage and increase the withstand voltage between the switching terminals of the relay.

In this case, if these functions were housed in the D/P package, the configuration would be as shown in the internal connection diagram of FIG. 4.

One photovoltaic diode array D is placed on the light receiving element pellet 14 that receives light emitted from the light emitting diode D1.
From the anode side electrode 3, the back side is the drain electrode and is mounted on the island 15 of the lead frame
A bonding wire 20 is wired to the gate electrode of S F E T Q +, and the photovoltaic diode array D2
A bonding wire 21 is wired from the cathode electrode 4 of the MOSFET Q1 to the source electrode S of the MOSFET Q, and a bonding wire 22 is also wired to the island portion 16 of the lead frame on which the other MOSFET Q is mounted. has been done. Furthermore, from the anode electrode 5 of another photovoltaic diode array D, a MOSFET
A bonding wire 23 is wired to the gate electrode G of the MOSFET Qs, and a bonding wire 24 is wired from the cathode electrode 6 to the MOSFET Q and the source electrode S. A floating wire 25 is wired to the island portion 17.

[Problem to be solved by the invention]

The conventional semiconductor relay circuit described above uses MOSFETs to connect 2 m of N-channel Enhancement (WMOSFET) in series.
In addition to the two islands of the lead frame on which the SFET element is mounted, another island is required to serve as the output terminal, which increases the number of extra terminals in the package, resulting in poor mounting efficiency. Two M
Since it serves as the drain electrode of the OSFET and the source electrode of the other MOSFET, it has the disadvantage that there is no symmetry in terms of the circuit and the wiring is complicated.

In addition, when a circuit is constructed using one MOSFET element with high withstand voltage, RH (.n> ” (B VD8
) ”, so if the total area of the elements is equal,
The disadvantage is that the on-resistance is higher than when it is assembled with several MOSFET elements.

An object of the present invention is to eliminate such drawbacks, simplify internal wiring by using a P-channel enhancement MOSFET instead of an N-channel enhancement MOSFET as an open/close switch, and provide a semiconductor relay circuit that has an increased breakdown voltage of an output switch. It's about doing.

[Means to solve the problem]

The structure of the semiconductor relay circuit of the present invention includes a light emitting diode that emits light in response to an input current, first and second photovoltaic diode arrays that receive output light from the light emitting diode, and a light emitting diode that generates light in these photovoltaic diodes. N-channel and P-channel enhancement type MOSFETs are respectively driven by currents and serve as output switches, the drain of the N-channel MO3FET is used as the positive output terminal of the relay, and the drain of the P-channel MOSFET is used as the negative terminal of the relay. the gates of the N-channel and P-channel MOSFETs are connected to the anodes of the first and second photovoltaic diode arrays, and the sources thereof are connected to the cathodes of the first and second photovoltaic diode arrays;
It is characterized in that the sources of the channel and P-channel MOSFETs are commonly connected.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

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

A light emitting diode °D is connected to input terminals 1 and 2,
Anode electrode 3 to N of photovoltaic diode array D2
It is connected to the gate electrode G of the channel enhancement type MO3FET Q, and further wired from the cathode electrode 4 to the source electrode S. Further, a cathode electrode 6 is connected from the anode electrode 5 of the photovoltaic diode array D to the source electrode S of the P-channel enhancement type MOSFET Q2.
It is wired to the gate electrode G.

Moreover, photovoltaic diode array D2. A discharge resistor Rl is connected in parallel to the anode electrodes 3, 5 and cathode electrodes 4, 6 of D3.
, R2 are connected, and a train of N-channel enhancement type MOS FET Q1 is connected.
[ID,! -P channel enhancement type MOSFE
The drain electrode of TQ2 is the positive output terminal 11. It serves as a negative polarity output terminal 12. N-channel enhancement Mj1M OS FET
Q1 and P channel enhancement type MOS
The respective source electrodes S of FETQ2 are commonly connected.

Next, the operation of this circuit will be explained.

When an input signal flows between input terminals 1 and 2, the light emitting diode D1 emits light, and this light is transmitted to the photovoltaic diode array D.
z and Ds, and the generated photocurrent charges the gate-source capacitance of the N-channel enhancement type MOSFET Q1 and the P-channel enhancement type MO3FET Q2, turning each MOSFET into an on state. In this state, a current from an external load flows into the positive output terminal 11 and flows out from the negative output terminal 12.

Also, if there is no input signal, two MOSFET Q
,,Q, are in the off state, so the voltage of the external load is 2.
This is blocked by the sum of the drain-source breakdown voltages of the two MOSFETs, and no current flows to the load.

Also, when a MOSFET transitions from an on state to an off state, or from an off state to an on state, if there is a difference in the turn-on and turn-off times of this MOSFET, the voltage of the load circuit may be applied to only one side of the MOSFET. . Therefore, it is also important to select a MOSFET that can withstand pulsed voltage.

Next, the internal connection diagram of the DIP package of this embodiment will be explained.
A bonding wire 20 is connected from the anode electrode 3 of one photovoltaic diode array D2 on the photovoltaic diode array D2 to the gate electrode G of an N-channel enhancement type MOSFET Q, whose back surface is the drain electrode and is mounted on the island 15 of the lead frame. A bonding wire 21 is wired from the cathode electrode 4 of the photovoltaic diode array D to the source electrode S. Further, from the anode electrode 5 of another photovoltaic diode array D on the light receiving element bezel 14, a P-channel enhancement type MOSFET Q whose back surface is a drain electrode and is mounted on the island 16 of the lead frame is connected. 2 source electrode S
A bonding wire 22 is wired to the gate electrode G, and a bonding wire 23 is wired from the cathode electrode 6 to the gate electrode G.

〔Effect of the invention〕

As explained above, the present invention provides a semiconductor relay circuit that symmetrically combines an N-channel enhancement type MOSFET and a P-channel enhancement type MOSFET as an output switch, thereby simplifying internal wiring and increasing the withstand voltage of the output switch. There is an effect that you can obtain.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is an internal connection diagram of the semiconductor relay shown in Fig. 1, Fig. 3 is a circuit diagram of an example of a conventional semiconductor relay, and Fig. 4 is a circuit diagram of an example of the conventional semiconductor relay. FIG. Dl... Light emitting diode, D2. Dl...
・Photovoltaic diode array% Qll Q3...
・・N-channel enhancement type MOS F E
T, Q 1...P channel enhancement mMo S F E T -R1, R2...Discharge resistance, 1, 2...Input terminal, 3, 5...
...Anode electrode, 4,6...Cathode electrode,
11... Positive polarity output terminal, 12... Negative polarity output terminal, 14... Light receiving element pellet, 1
5~F...Lead frame island section, 2
0-25...Ponding wire.

Claims (1)

[Claims] A light emitting diode that emits light based on an input current, first and second photovoltaic diode arrays that receive output light from the light emitting diode, and an N channel that is driven by the current generated in these photovoltaic diodes and serves as an output switch. and each enhancement type M of the P channel
OSFET, the drain of the N-channel MOSFET is used as the positive output terminal of the relay, the drain of the P-channel MOSFET is used as the negative output terminal of the relay, and each gate of the N-channel and P-channel MOSFET is connected to the first and an anode of a second photovoltaic diode array, each of which has its respective source connected to its cathode, and each of said N-channel and P-channel MOSFETs.
A semiconductor relay circuit characterized in that ET sources are commonly connected.