A high assembly density voltage input type optical disconnector

Abstract

The application discloses a high-assembly-density voltage input type optical isolation switch, which comprises a tube shell, an input circuit and an output circuit. The input circuit comprises a light-emitting diode D1, a resistor R1 and a resistor R2, current limiting is realized through the resistor R1, and voltage direct driving is realized through parallel protection of the resistor R2; the output circuit comprises a photovoltaic diode E1 and a field effect tube, and a driving voltage is generated through a photovoltaic effect to control the field effect tube to be turned on and turned off. Through the current limiting effect and anti-interference protection of the resistor, direct voltage input control is realized, an external current limiting resistor is not needed, circuit design is simplified, use cost is reduced, and design convenience is improved. A cover plate, a substrate and a tube seat are adopted in a three-layer laminated structure, the photovoltaic diode is attached to the substrate, the light-emitting diode is attached to the tube seat, and the photovoltaic diode is located directly above the light-emitting diode; the optical path is short, light loss is small, photoelectric conversion efficiency is improved, meanwhile, three electric connection paths do not cross each other, short circuit risk is reduced, and product reliability is improved.

Description

Technical Field

[0001] This invention relates to the field of solid-state relay technology, and more specifically to a high-density voltage input type opto-isolating switch. Background Technology

[0002] Optically isolated switches are switching devices that use optoelectronic isolation between input and output. Each channel has two input leads and two output leads, with a contactless output and no electromagnetic interference between input and output. Therefore, they are widely used in industrial control, communication equipment, medical devices, aerospace, and other fields. Existing opto-isolated solid-state relays or opto-isolated switches generally suffer from low power density, resulting in either large switch size or low output current. Furthermore, their input control is primarily current-driven, requiring external current-limiting resistors to regulate the input current, leading to complex circuit design and high power consumption. This fails to meet the demands of modern electronic devices for miniaturization, high integration, and convenient design. For example, CN119921745A discloses an opto-isolated solid-state relay, including an input delay circuit, an input discharge circuit, an isolation module, an output delay circuit, an output anti-interference circuit, and a MOSFET. This relay uses complex input delay and discharge circuits to improve reliability, but its input control is still current-driven, requiring external current-limiting resistors, and its complex internal circuit structure results in a large device size, hindering high-density integration. For example, CN201911057832 discloses a fast-switching optically isolated solid-state relay, including an input circuit mounted on a substrate and an output circuit mounted on a base. The input circuit uses two light-emitting diodes to illuminate a photovoltaic diode array. Although this relay improves the switching rate and turn-on speed, its input circuit still requires an external current-limiting resistor, and the substrate and base are separate structures, which is not conducive to the overall miniaturization of the device and results in low power density. Therefore, there is an urgent need to design a high-density, voltage-input type optically isolated switch to achieve direct voltage drive, reduce size, and increase power density. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a high-density voltage input opto-isolating switch. This invention achieves direct voltage drive by optimizing the input circuit structure and improves the assembly density and power density through an innovative stacked housing structure design, thus solving the technical problems of complex input control, large size, and low power density of opto-isolating switches in the prior art.

[0004] The technical solution of the present invention: A high-density voltage input optically isolated switch includes a housing, an input circuit, and an output circuit.

[0005] The input circuit includes an LED D1, resistors R1 and R2. The positive terminal of the input power supply is connected to the anode of LED D1 and one end of resistor R2 via resistor R1, while the negative terminal is connected to the cathode of LED D1 and the other end of resistor R2. Resistor R1 is connected in series in the branch between the input power supply and LED D1. Utilizing the current-limiting effect of resistor R1, the input voltage is converted into an appropriate drive current flowing through LED D1, allowing a voltage signal to be directly applied to the switch input without the need for an external current-limiting resistor. Simultaneously, resistor R2 is connected in parallel across LED D1, forming a shunt branch. When a transient interference voltage occurs at the input terminal, resistor R2 absorbs some of the interference current, preventing LED D1 from being damaged due to overcurrent, thereby improving the product's anti-interference capability and reliability. Through the synergistic effect of R1 and R2, a voltage-input type drive mode is achieved, simplifying the external circuit design.

[0006] The output circuit includes a photovoltaic diode E1 and a field-effect transistor (FET). The positive terminal of the photovoltaic diode E1 is connected to the gate of the FET, and the negative terminal is connected to the source of the FET. When the light-emitting diode D1 emits light and illuminates the photovoltaic diode E1, the photovoltaic diode E1 generates a photovoltage based on the photovoltaic effect. This voltage is applied between the gate and source of the FET, forming a gate-source drive voltage that controls the conduction and turn-off of the FET. When there is one MOSFET, its drain and source form the output terminal of the output circuit, creating a unidirectional switch structure. The output current can only flow in one direction, suitable for DC load control applications. When there are two MOSFETs, V1 and V2, the positive terminal of the photovoltaic diode E1 is connected to the gates of both MOSFETs V1 and V2, and the negative terminal of the photovoltaic diode E1 is connected to the sources of both MOSFETs V1 and V2. The drains of MOSFETs V1 and V2 form the two output terminals of the output circuit, creating a bidirectional switch structure. The two MOSFETs are connected in reverse series, allowing the output current to flow bidirectionally, suitable for AC load control applications. By using both single and dual MOSFET configurations, flexible adaptation between unidirectional and bidirectional switching functions is achieved.

[0007] The tube housing includes a cover plate, a substrate, and a tube base. Input leads and output leads are provided on both sides of the tube base. The light-emitting diode D1 is mounted on the tube base, and the photovoltaic diode E1 is mounted on the substrate, with the photovoltaic diode E1 located directly above the light-emitting diode D1. The system employs a three-layer stacked structure consisting of a cover plate, substrate, and socket. Photovoltaic diode E1 is mounted on the substrate, and light-emitting diode D1 is mounted on the socket, with photovoltaic diode E1 positioned directly above light-emitting diode D1. This vertical stacking structure allows light emitted from light-emitting diode D1 to directly illuminate photovoltaic diode E1, resulting in a short optical path, low light loss, and improved photoelectric conversion efficiency. Furthermore, placing photovoltaic diode E1 on the substrate and light-emitting diode D1 on the socket, contrary to traditional mounting methods, allows the output of photovoltaic diode E1 to be easily electrically connected to the field-effect transistor chip via bonding wires on the substrate. Light-emitting diode D1 is electrically connected to the input lead via bonding wires and the embedded metal of the socket, while the output-side field-effect transistor is electrically connected to the output lead via bonding wires and the embedded metal of the socket. These three electrical connection paths do not intersect, reducing the risk of short circuits and improving the reliability of the optical isolator.

[0008] The socket is equipped with a high-low stack and a cavity isolation wall, and has at least two field-effect transistor (FET) mounting areas. The high-low stack structure on the socket uses a stepped design of different heights to vertically offset the mounting areas of the LED D1 and the FETs. Simultaneously, the cavity isolation wall physically isolates the FET mounting areas from the LED D1 mounting areas. This achieves electrical and optical isolation between the input and output sides, preventing optical crosstalk and electromagnetic interference between paths. Furthermore, each path within the same socket can have two FET mounting areas, located on either side of the cavity isolation wall. This allows each path to be equipped with either one FET to form a unidirectional switch or two FETs to form a bidirectional switch. This achieves a universal design where unidirectional and bidirectional switches share the same casing, significantly reducing the size of the optically isolated switch and increasing its power density.

[0009] The high-density voltage-input opto-isolating switch is a 1-channel, 2-channel, or 4-channel switch. Each channel has identical input and output circuits, and all channels are electrically isolated from each other. The technical principle is that each channel has independent input and output circuits, and physical and electrical isolation is achieved between channels through a cavity isolation wall. This allows multiple independent switching channels to be integrated within the same housing. Powering on each channel's input independently controls the on / off state of its corresponding output, and there is no electrical connection between channels, avoiding inter-channel crosstalk and improving integration and flexibility of use.

[0010] The package can be LCC, SOP, or DIP. Depending on the application scenario and installation requirements, three package types can be selected: leadless chip carrier LCC, small outline SOP, or dual in-line package (DIP). LCC packaging features small size and high pin density, suitable for high-density surface mount applications; SOP packaging features standard pin spacing and ease of automated soldering, suitable for general surface mount applications; DIP packaging features convenient insertion, easy manual soldering and replacement, suitable for experimental and prototyping applications. This flexible selection of three package types allows the optically isolated switch of this invention to adapt to different application needs.

[0011] The beneficial effects of this invention are: Employing a voltage-input drive method, direct voltage input control is achieved through the current-limiting effect and anti-interference protection of the resistor, eliminating the need for an external current-limiting resistor, simplifying circuit design, reducing operating costs, and improving design convenience. A three-layer stacked structure of cover plate, substrate, and socket is used, with the photovoltaic diode mounted on the substrate and the light-emitting diode mounted on the socket, and the photovoltaic diode positioned directly above the light-emitting diode. This results in a short optical path, low light loss, and improved photoelectric conversion efficiency. Furthermore, the three electrical connection paths do not intersect, reducing the risk of short circuits and improving product reliability. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the principle of the single-channel input / output unidirectional isolation switch of the present invention.

[0013] Figure 2 This is a schematic diagram of the principle of the one-way input / output bidirectional isolation switch of the present invention.

[0014] Figure 3 This is a schematic diagram of the principle of the two-way input / output unidirectional isolation switch of the present invention.

[0015] Figure 4 This is a schematic diagram of the principle of the two-way input / output bidirectional isolation switch of the present invention.

[0016] Figure 5 This is a schematic diagram of the principle of the 4-channel input / output unidirectional isolation switch of the present invention.

[0017] Figure 6 This is a schematic diagram of the principle of the 4-channel input / output bidirectional isolation switch of the present invention.

[0018] Figure 7 and Figure 8 This is a schematic diagram of the LCC package structure of the 1-channel disconnect switch of the present invention.

[0019] Figure 9 This is a schematic diagram of the internal structure of the 1-channel input / output unidirectional isolating switch of the present invention.

[0020] Figure 10 This is a schematic diagram of the internal structure of the one-way input / output bidirectional isolation switch of the present invention.

[0021] Figure 11 This is a cross-sectional schematic diagram of the one-way input / output bidirectional isolation switch of the present invention.

[0022] In the diagram: 1-Cover plate; 2-Substrate; 3-Socket; 4-Input lead; 5-Output lead; 6-Bonding wire; D1-Light emitting diode chip; E1-Photovoltaic diode chip; V1-Field-effect transistor chip; V2-Field-effect transistor chip. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0024] Example 1: 1-channel unidirectional optically isolated switch Please see Figure 1 , Figure 7 , Figure 8 and Figure 9 This embodiment provides a single-channel input / output unidirectional high-density voltage input opto-isolating switch. The opto-isolating switch includes a housing, an input circuit, and an output circuit.

[0025] The housing includes a cover plate 1, a substrate 2, and a socket 3. Input leads 4 and output leads 5 are located on both sides of the socket 3. The housing uses an LCC package with a lead-out spacing of 2.54 mm. Inside the housing, from top to bottom, are the cover plate 1, the substrate 2, a photovoltaic diode E1 mounted on the substrate 2, a light-emitting diode D1 mounted on the socket 3, and the socket 3 itself. The photovoltaic diode E1 is positioned directly above the light-emitting diode D1, allowing the light emitted by the light-emitting diode D1 to directly illuminate the photovoltaic diode E1.

[0026] The input circuit includes a light-emitting diode (LED) D1, resistors R1 and R2. The positive terminal of the input power supply is connected to the anode of LED D1 and one end of resistor R2 via resistor R1, and the negative terminal of the input power supply is connected to the cathode of LED D1 and the other end of resistor R2. Resistor R1 has a resistance of 470Ω and is used to convert the input voltage into a drive current of approximately 10mA; resistor R2 has a resistance of 10kΩ and is used to absorb transient interference current.

[0027] The output circuit includes a photovoltaic diode E1 and a field-effect transistor V1. The positive terminal of the photovoltaic diode E1 is connected to the gate of the field-effect transistor V1, and the negative terminal is connected to the source of the field-effect transistor V1. The drain and source of the field-effect transistor V1 form the output terminal of a unidirectional switch.

[0028] The socket 3 is provided with high and low layers and a cavity isolation wall. The light-emitting diode D1 is mounted in the lower layer area of ​​the socket 3, and the field-effect transistor V1 is mounted in the higher layer area of ​​the socket 3. The cavity isolation wall physically isolates the two areas. The output of the photovoltaic diode E1 is electrically connected to the gate and source of the field-effect transistor V1 through the bonding wire 6 on the substrate 2; the light-emitting diode D1 is electrically connected to the input lead 4 through the bonding wire and the embedded metal of the socket 3; the field-effect transistor V1 is electrically connected to the output lead 5 through the bonding wire and the embedded metal of the socket 3.

[0029] The working principle of this embodiment is as follows: When no voltage is applied to the input terminal, LED D1 does not emit light, photovoltaic diode E1 does not generate voltage due to lack of light, and the gate of MOSFET V1 has no driving voltage. At this time, the drain and source of MOSFET V1 are in a turned-off state, and the output terminals of the opto-isolation switch are in a disconnected state. When a voltage (such as 5V DC voltage) is applied to the input terminal, the current flows through LED D1 after being limited by resistor R1, driving LED D1 to emit light. The emitted light shines upward onto the photovoltaic diode E1 located directly above. Photovoltaic diode E1 generates a photovoltage of approximately 5V based on the photovoltaic effect. This voltage is applied between the gate and source of MOSFET V1, causing MOSFET V1 to conduct, and the output terminals of the opto-isolation switch are in a conducting state. When the input voltage is removed, LED D1 turns off, photovoltaic diode E1 no longer generates voltage, the gate charge of MOSFET V1 is released through the internal discharge circuit, MOSFET V1 turns off, and the output returns to the disconnected state.

[0030] The power density of the optically isolated switch in this embodiment is 6000 W / cm². 3 The input control voltage range is 3V to 32V, the maximum output load voltage is 60V, and the maximum output load current is 2A.

[0031] Example 2: One-way bidirectional optically isolated switch Please see Figure 2 , Figure 10 and Figure 11 This embodiment provides a one-channel input / output bidirectional high assembly density voltage input type optical isolation switch.

[0032] The casing structure and input circuit of this embodiment are the same as those of Embodiment 1. The only difference is that the output circuit uses two field-effect transistors (FETs) V1 and V2 to form a bidirectional switch structure. The positive terminal of photovoltaic diode E1 is connected to the gates of FETs V1 and V2, respectively, and the negative terminal of photovoltaic diode E1 is connected to the sources of FETs V1 and V2, respectively. The drains of FETs V1 and V2 form the two output terminals of the bidirectional switch. The two FETs are connected in series in reverse order, allowing the output current to flow bidirectionally.

[0033] The tube socket 3 is provided with two field-effect transistor mounting areas, located on both sides of the cavity isolation wall, and field-effect transistors V1 and V2 are mounted in the two mounting areas respectively.

[0034] The working principle of this embodiment is basically the same as that of embodiment 1. The difference is that when a voltage is applied to the input terminal, the photogenerated voltage generated by the photovoltaic diode E1 is simultaneously applied to the gates of the field-effect transistors V1 and V2. The two field-effect transistors are turned on at the same time, so that the current can be bidirectionally conducted on both sides of the output terminal, which is suitable for AC load control applications.

[0035] The power density of the optically isolated switch in this embodiment is 5500 W / cm². 3 The input control voltage range is 3V to 32V, the maximum output load voltage is 60V, and the maximum output load current is 1.5A (bidirectional).

[0036] Example 3: 4-channel unidirectional optically isolated switch Please see Figure 5 and Figure 6 This embodiment provides a 4-channel input / output unidirectional high assembly density voltage input type optically isolated switch.

[0037] This embodiment includes four independent switching channels. The input and output circuits of each channel are the same as in Embodiment 1, and the channels are electrically isolated from each other. The four switches are integrated into the same housing, which is in SOP package form. Each channel can be controlled independently; when the input is powered on, the corresponding channel's output is turned on, and when the input is not powered on, the corresponding channel's output is turned off.

[0038] The power density of the optically isolated switch in this embodiment is 4500 W / cm². 3 Each input control voltage range is 3V to 32V, each output load voltage is up to 60V, and each output load current is up to 1A.

[0039] Example 4: Different Packaging Forms This embodiment illustrates three packaging forms of the optically isolating switch of the present invention.

[0040] LCC package: such as Figure 7 and Figure 8 As shown, it adopts a leadless chip carrier package, with input and output leads led out from both sides of the socket in the form of pads. It is suitable for high-density surface mount and the package size is 9.0mm×7.0mm×3.0mm.

[0041] SOP package: Small outline package with input and output leads extending from both sides of the socket in gull-wing form with a lead pitch of 1.27mm. Suitable for standard surface mount processes, package size is 10.3mm × 7.5mm × 2.5mm.

[0042] DIP package: The dual in-line package has input and output leads that are led out from both sides of the socket in the form of through pins with a pin pitch of 2.54mm. It is suitable for through-hole mounting and manual soldering. The package size is 12.7mm × 9.5mm × 3.5mm.

[0043] The three packaging types mentioned above differ only in the shape and size of the leads; their internal circuit structure and functions are completely identical, allowing for flexible selection based on actual application requirements.

Claims

1. A high-density voltage input type opto-isolating switch, comprising a housing, an input circuit, and an output circuit, characterized in that: The input circuit includes a light-emitting diode D1, a resistor R1 and a resistor R2. The positive terminal of the input power supply is connected to the anode of the light-emitting diode D1 and one end of the resistor R2 via the resistor R1, and the negative terminal of the input power supply is connected to the cathode of the light-emitting diode D1 and the other end of the resistor R2. The output circuit includes a photovoltaic diode E1 and a field-effect transistor; the positive terminal of the photovoltaic diode E1 is connected to the gate of the field-effect transistor, and the negative terminal is connected to the source of the field-effect transistor. When there is one field-effect transistor (FET), the drain and source of the FET constitute the output terminal of the output circuit; when there are two FETs, the two FETs are V1 and V2, the positive terminal of the photovoltaic diode E1 is connected to the gate of FET V1 and FET V2 respectively, the negative terminal of the photovoltaic diode E1 is connected to the source of FET V1 and FET V2 respectively, and the drain of FET V1 and the drain of FET V2 constitute the two output terminals of the output circuit respectively. The casing includes a cover plate (1), a substrate (2) and a tube seat (3). The tube seat (3) has an input lead (4) and an output lead (5) on both sides. The light-emitting diode D1 is mounted on the tube seat (3), and the photovoltaic diode E1 is mounted on the substrate (2), with the photovoltaic diode E1 located directly above the light-emitting diode D1. The tube seat (3) has a high-low stack and a cavity isolation wall, and at least two field-effect transistor mounting areas.

2. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The resistor R1 is connected in series in the branch between the input power supply and the light-emitting diode D1 to limit the input current; the resistor R2 is connected in parallel across the two ends of the light-emitting diode D1 to prevent input interference.

3. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The number of field-effect transistors is one, and it is denoted as field-effect transistor V1. The positive terminal of the photovoltaic diode E1 is connected to the gate of field-effect transistor V1, and the negative terminal of the photovoltaic diode E1 is connected to the source of field-effect transistor V1. The drain and source of field-effect transistor V1 constitute the output terminal of a unidirectional switch.

4. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The number of field-effect transistors is two, and they are respectively denoted as field-effect transistor V1 and field-effect transistor V2; the positive terminal of photovoltaic diode E1 is connected to the gate of field-effect transistor V1 and field-effect transistor V2 respectively, the negative terminal of photovoltaic diode E1 is connected to the source of field-effect transistor V1 and field-effect transistor V2 respectively, and the drain of field-effect transistor V1 and the drain of field-effect transistor V2 respectively constitute the two output terminals of the bidirectional switch.

5. The high assembly density voltage input type opto-isolating switch according to claim 1, characterized in that: The inside of the tube shell consists of, from top to bottom, a cover plate (1), a substrate (2), a photovoltaic diode E1 mounted on the substrate (2), a light-emitting diode D1 mounted on the tube socket (3), and the tube socket (3).

6. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The high assembly density voltage input type optical isolating switch is a 1-way switch, a 2-way switch, or a 4-way switch. The input circuit and output circuit of each channel are the same, and each channel is electrically isolated from the others.

7. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The casing is packaged in the form of LCC package, SOP package or DIP package.

8. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The output of the photovoltaic diode E1 is electrically connected to the field-effect transistor chip through the bonding wire (6) on the substrate (2); the light-emitting diode D1 is electrically connected to the input lead (4) through the bonding wire and the embedded metal of the socket (3); the field-effect transistor on the socket (3) is electrically connected to the output lead (5) through the bonding wire and the embedded metal of the socket (3).

9. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: The power density of the optically isolated switch is 4000–8000 W / cm². 3 The power density is defined as the ratio of the product of the maximum output voltage and the maximum output current of the product at 25°C to the product's casing volume.

10. The high assembly density voltage input type optically isolated switch according to claim 1, characterized in that: At least two field-effect transistor mounting areas on the socket (3) are distributed on both sides of the cavity isolation wall, and the cavity isolation wall physically isolates the field-effect transistor mounting areas from the mounting areas of the light-emitting diode D1.

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