Opto-coupler with high voltage input tolerance

Abstract

The utility model discloses a kind of photoelectric couplers of high-voltage input resistance, including first frame unit, second frame unit, luminous chip, photosensitive chip, zener chip and packaging structure, two independent chip mounting parts are equipped on the first frame unit, respectively install luminous chip and zener chip respectively fixed two chip mounting parts, and both are connected in series by first bonding line;Photosensitive chip is fixed on the second frame unit, and position is opposite with luminous chip;The packaging structure is packaged into an organic whole with first frame unit, second frame unit, zener chip, luminous chip, photosensitive chip.The utility model is connected in series with zener chip and luminous chip in packaging structure, realizes protection function using the reverse breakdown voltage stabilizing characteristic of zener chip, clamps reverse voltage applied at the two ends of luminous chip in its tolerable safety range, improves the working stability of photoelectric coupler under high reverse voltage scene.

Description

Technical Field

[0001] This utility model relates to the field of optocoupler technology, and in particular to an optocoupler that can withstand high voltage input. Background Technology

[0002] Optocouplers, as electronic components that transmit electrical signals using light as a medium, are widely used in many fields such as industrial control, power systems, and communication equipment due to their core characteristic of electrical isolation between the input and output circuits. They effectively suppress electromagnetic interference and block the effects of ground potential differences, making them one of the key components for ensuring the safe and stable operation of circuits.

[0003] Traditional optocouplers typically use GaAs (gallium arsenide) infrared emitting diodes at their input terminals. These diodes emit infrared light to trigger photosensitive elements (such as phototransistors and photothyristors) at the output terminals, thereby completing signal coupling and transmission. However, GaAs infrared emitting diodes have significant limitations—their reverse voltage withstand capability is weak, typically only able to withstand a reverse voltage of 20 to 30 volts.

[0004] In some practical applications, the circuit environment places high demands on the reverse withstand voltage of components. For example, in the feedback control loops of some high-voltage power supplies, or in industrial control circuits with transient high-voltage pulses, components often need to have a reverse withstand voltage of over 80V. In these cases, traditional optocouplers based on GaAs infrared emitting diodes are unsuitable. If applied to circuits with such high reverse voltage requirements, the GaAs infrared emitting diode at the input terminal is easily damaged and broken down if it encounters a reverse voltage surge exceeding its withstand value. This not only leads to the failure of the optocoupler itself but may also cause abnormalities in the entire circuit system due to component failure, or even more serious equipment damage.

[0005] Moreover, this application limitation caused by insufficient reverse voltage withstand capability is not due to insufficient chip performance parameters, but rather stems from the inherent physical properties of GaAs material itself, which limit its reverse voltage withstand capability. Therefore, simply optimizing chip design and improving chip manufacturing processes cannot solve this problem. To enable optocouplers to meet the application requirements of high reverse voltage scenarios, new solutions need to be explored at the component packaging level. Utility Model Content

[0006] To address the aforementioned issues, this invention provides an optocoupler capable of withstanding high voltage input, which improves the input terminal's resistance to current surges and enhances its applicability.

[0007] Therefore, the technical solution of this utility model is: an optocoupler resistant to high voltage input, comprising a first frame unit, a second frame unit, a light-emitting chip, a photosensitive chip, a Zener chip, and a packaging structure. The first frame unit is provided with two independent chip mounting parts, on which the light-emitting chip and the Zener chip are respectively mounted and fixed, and the two are connected in series by a first bonding wire. The second frame unit is fixed with the photosensitive chip, which is positioned opposite to the light-emitting chip. The packaging structure encapsulates the first frame unit, the second frame unit, the Zener chip, the light-emitting chip, and the photosensitive chip into one unit.

[0008] Based on the above scheme and as a preferred embodiment of the above scheme: the first frame unit is further provided with a first pin and a second pin, the first pin is connected to the first chip mounting part where the Zener chip is located, and the second pin is connected to the second chip mounting part where the light-emitting chip is located.

[0009] Based on the above scheme and as a preferred embodiment of the above scheme: the light-emitting chip is a GaAs infrared emitting diode, which is welded and fixed to the second chip mounting part; the Zener chip is welded and fixed to the first chip mounting part.

[0010] Based on the above scheme and as a preferred embodiment of the above scheme: the current in the first frame unit flows in from the first pin, flows through the Zener chip, the first bonding wire, and the light-emitting chip in sequence, and then flows out from the second pin.

[0011] Based on the above scheme and as a preferred embodiment of the above scheme: the second frame unit is provided with a third pin, a fourth pin, a third chip mounting part and a bonding part, the third pin is connected to the third chip mounting part, and the photosensitive chip is fixed on the third chip mounting part; the fourth pin is connected to the bonding part, and the bonding part and the photosensitive chip are electrically connected through a second bonding wire.

[0012] Compared with the prior art, the beneficial effects of this utility model are: 1. A Zener diode and an LED are connected in series within the package structure, utilizing the reverse breakdown voltage regulation characteristic of the Zener diode to achieve protection. When the circuit experiences an excessive reverse voltage surge, the Zener diode will enter a breakdown state when the reverse voltage reaches its set breakdown threshold, clamping the reverse voltage applied across the LED within its tolerable safe range. This effectively avoids the problem of GaAs infrared emitting diodes being broken down by high reverse voltage surges in traditional optocouplers, significantly reducing the probability of device damage and failure, and fundamentally improving the operational stability of the optocoupler in high reverse voltage scenarios.

[0013] 2. The Zener chip and the light-emitting chip are integrated on the independent chip mounting part of the first frame unit and electrically connected through the first bonding wire. At the same time, the components are packaged into one unit with the packaging structure. The overall structure is compact and does not interfere with the core signal transmission path of the optocoupler. An effective solution is provided from the packaging level.

[0014] 3. Without changing the material or performance of core components such as the light-emitting chip, the Zener chip can be integrated and packaged with existing light-emitting chips and photosensitive chips. This allows the optocoupler to meet the needs of high reverse voltage applications such as high-voltage power supply feedback control loops and industrial control circuits with instantaneous high-voltage pulses, greatly expanding the application fields of optocouplers and improving the market applicability of the product. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the structure of the first frame unit of this utility model; Figure 3 for Figure 2 A magnified view of a portion of the image; Figure 4 This is a schematic diagram of the structure of the second frame unit of this utility model.

[0016] The components in the diagram are labeled as follows: First frame unit 1, First pin 11, Second pin 12, First chip mounting part 13, Second chip mounting part 14, Second frame unit 2, Third pin 21, Fourth pin 22, Third chip mounting part 23, Wire bonding part 24, Zener chip 3, Light-emitting chip 4, Photosensitive chip 5, First bonding wire 6, Second bonding wire 7, and Package structure 8. Detailed Implementation

[0017] See the attached figures. The optocoupler with high voltage input described in this embodiment includes a first frame unit 1, a second frame unit 2, a Zener chip 3, a light-emitting chip 4, a photosensitive chip 5, and a packaging structure 8.

[0018] The first frame unit 1 is provided with a first pin 11, a second pin 12, and independent first chip mounting parts 13 and second chip mounting parts 14. The first pin 11 is connected to the first chip mounting part 13, and the second pin 12 is connected to the second chip mounting part 14. The Zener chip 3 is soldered and fixed to the first chip mounting part 13; the light-emitting chip 4 is a GaAs infrared emitting diode, which is soldered and fixed to the second chip mounting part 14; the light-emitting chip 4 and the Zener chip 3 are connected in series through a first bonding wire 6; current flows in from the first pin 11, flows sequentially through the Zener chip 3, the first bonding wire 6, and the light-emitting chip 4, and then flows out from the second pin 12, thereby forming a current loop at the light-emitting end.

[0019] The second frame unit 2 is provided with a third pin 21, a fourth pin 22, a third chip mounting part 23 and a bonding part 24. The third pin 21 is connected to the third chip mounting part 23, and the photosensitive chip 5 is fixed on the third chip mounting part 23. The fourth pin 22 is connected to the bonding part 24, and the bonding part 24 is electrically connected to the photosensitive chip 5 through the second bonding wire 7.

[0020] The encapsulation structure 8 is made of black opaque epoxy resin. During encapsulation, the first frame unit 1 and the second frame unit 2 are arranged opposite to each other. The photosensitive chip 5 on the second frame unit 2 is positioned opposite to the light-emitting chip 4 on the first frame unit 1. Then, the first frame unit, the second frame unit, the Zener chip, the light-emitting chip, and the photosensitive chip are encapsulated into one piece using epoxy resin to form a black encapsulation structure 8, with only the pins exposed.

[0021] When the circuit is operating in the forward direction or the reverse voltage does not exceed the safety threshold, the Zener chip is in the off state. In forward operation, the input signal voltage is applied to the light-emitting chip, causing it to emit light normally (meeting the operating conditions of a GaAs infrared emitting diode). The light signal triggers the photosensitive element at the output terminal, completing the signal transmission function of optocoupler. When the reverse voltage is low (not reaching the breakdown voltage of the Zener chip), the reverse voltage is mainly borne by the light-emitting chip. Since the voltage does not exceed its own reverse voltage limit of 20-30 volts, the light-emitting chip will not be damaged and can still maintain a stable state.

[0022] When the circuit experiences a reverse voltage surge exceeding 80V, the Zener chip enters a reverse breakdown state, providing protection. The Zener chip has a fixed reverse breakdown voltage. When the reverse surge voltage exceeds this breakdown voltage, the reverse resistance of the Zener chip decreases sharply. At this point, most of the reverse current is shunted through the Zener chip, effectively creating a "low-resistance path" in parallel across the LED, clamping the reverse voltage applied to the LED below its breakdown voltage, keeping it within the LED's tolerable range of 20-30 volts. Through this mechanism of "active breakdown and current clamping under high reverse voltage," the LED will not be damaged by reverse voltages exceeding its limits, thus achieving input-side resistance to reverse voltage surges exceeding 100V without affecting signal coupling during normal operation.

[0023] The above description is merely a preferred embodiment of this utility model. The protection scope of this utility model is not limited to the above embodiments. All technical solutions falling within the scope of this utility model's concept are protected. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of this utility model should also be considered within the protection scope of this utility model.

Claims

1. An optocoupler resistant to high input voltage, characterized in that: The device includes a first frame unit, a second frame unit, a light-emitting chip, a photosensitive chip, a Zener chip, and a packaging structure. The first frame unit has two independent chip mounting parts, on which the light-emitting chip and the Zener chip are respectively mounted and fixed, and the two are connected in series by a first bonding wire. The second frame unit has a photosensitive chip fixed on it, and the photosensitive chip is positioned opposite to the light-emitting chip. The packaging structure encapsulates the first frame unit, the second frame unit, the Zener chip, the light-emitting chip, and the photosensitive chip into a single unit.

2. The optocoupler with high voltage input capability as described in claim 1, characterized in that: The first frame unit is also provided with a first pin and a second pin. The first pin is connected to the first chip mounting part where the Zener chip is located, and the second pin is connected to the second chip mounting part where the light-emitting chip is located.

3. The optocoupler with high voltage input capability as described in claim 2, characterized in that: The light-emitting chip is a GaAs infrared emitting diode, which is welded and fixed to the second chip mounting part; the Zener chip is welded and fixed to the first chip mounting part.

4. The optocoupler with high voltage input capability as described in claim 2, characterized in that: The current in the first frame unit flows in from the first pin, flows through the Zener chip, the first bonding wire, and the light-emitting chip in sequence, and then flows out from the second pin.

5. The optocoupler with high voltage input capability as described in claim 1, characterized in that: The second frame unit is provided with a third pin, a fourth pin, a third chip mounting part, and a wire bonding part. The third pin is connected to the third chip mounting part, and the photosensitive chip is fixed on the third chip mounting part. The fourth pin is connected to the wire bonding part, and the wire bonding part is electrically connected to the photosensitive chip through a second bonding wire.

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