Double-optocoupler protection circuit

Abstract

The utility model discloses a dual-optocoupler protection circuit, which comprises a chip U1, an optocoupler U2 and an optocoupler U3, and is characterized in that the FB end of the chip U1 is connected with the fourth pin of the optocoupler U2 and the fourth pin of the optocoupler U3; a pin 3 of the optocoupler U2 is connected with a pin 3 of the optocoupler U3; a pin 2 of the optocoupler U2 is connected with a pin 1 of the optocoupler U3; a pin 1 of the optocoupler U2 is connected with a resistor R121 and a resistor R98, the resistor R121 is connected with a voltage stabilizing diode ZD6, and the voltage stabilizing diode ZD6 is connected with a resistor R120; and the resistor R98 is connected with the pin 2 of the optocoupler U2 and the pin 1 of the optocoupler U3. According to the utility model, the damage of the power supply caused by failure of a single device can be met, the power supply and the personal safety of a user can be better protected, and the protection circuit can be better applied to the market due to more and more safety accidents caused by failure of a charger and higher and higher requirements on the safety of the charger at present.

Description

Technical Field

[0001] This utility model relates to the field of switching circuit technology, specifically a dual optocoupler protection circuit. Background Technology

[0002] Switching power supplies are a type of power supply that uses modern power electronics technology to control the duty cycle of switching transistors to maintain a stable output voltage. They have advantages such as small size, light weight, and high conversion efficiency, and have been applied in various fields.

[0003] In practical use, the failure of critical components in the charger can damage the power supply, potentially jeopardizing instruments, equipment, and personal safety. Currently, the primary and secondary windings are mainly isolated by an optocoupler for secondary signal control. If the optocoupler fails (short circuit, open circuit), primary feedback may fail, causing secondary voltage instability and damaging other circuits without protection. This power supply may damage the powered equipment or instruments or pose a safety hazard.

[0004] Therefore, a dual optocoupler protection circuit is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a dual optocoupler protection circuit to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A dual optocoupler protection circuit includes a chip U1, an optocoupler U2, and an optocoupler U3, wherein the FB terminal of the chip U1 is connected to pin 4 of the optocoupler U2 and pin 4 of the optocoupler U3.

[0008] Pin 3 of the optocoupler U2 is connected to pin 3 of the optocoupler U3;

[0009] Pin 2 of the optocoupler U2 is connected to pin 1 of the optocoupler U3;

[0010] Pin 1 of the optocoupler U2 is connected to resistors R121 and R98. Resistor R121 is connected to Zener diode ZD6, and Zener diode ZD6 is connected to resistor R120.

[0011] The resistor R98 is connected to pin 2 of optocoupler U2 and pin 1 of optocoupler U3.

[0012] Furthermore, the chip U1 is model number CR6855.

[0013] Furthermore, both optocoupler U2 and optocoupler U3 are model EL817.

[0014] Furthermore, a capacitor C19 is connected to pin 2 of the chip U1, and the capacitor C19 has a specification of 100pF / 50V.

[0015] Furthermore, the capacitor C19 is connected to pin 3 of optocoupler U2 and pin 3 of optocoupler U3.

[0016] Furthermore, the resistor R98 has a specification of 3KΩ.

[0017] Furthermore, resistor R120 is connected to resistor R96, resistor R96 is connected to Zener diode ZD5, Zener diode ZD5 is connected to resistor R97, and resistor R97 is connected to resistor R98.

[0018] Furthermore, resistor R98 is connected to resistor R122, and resistor R122 is connected to pin 2 of optocoupler U2 and pin 1 of optocoupler U3.

[0019] Furthermore, pin 2 of the optocoupler U3 is connected to Zener diode ZD7 and capacitor C28.

[0020] Compared with the prior art, the beneficial effects of this utility model are:

[0021] It can protect the power supply from damage caused by the failure of a single component, thus better protecting the power supply itself and the personal safety of the user. Nowadays, there are more and more safety accidents caused by charger failure, and the safety requirements for chargers are also getting higher and higher. Therefore, this kind of protection circuit is better applied in the market. Attached Figure Description

[0022] Figure 1 This is a circuit diagram of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0024] Example 1:

[0025] Please see Figure 1 This utility model provides a technical solution:

[0026] A dual optocoupler protection circuit includes a chip U1, an optocoupler U2, and an optocoupler U3. The circuit is characterized in that: the FB terminal of chip U1 is connected to pin 4 of optocoupler U2 and pin 4 of optocoupler U3; pin 3 of optocoupler U2 is connected to pin 3 of optocoupler U3; pin 2 of optocoupler U2 is connected to pin 1 of optocoupler U3; pin 1 of optocoupler U2 is connected to resistors R121 and R98, resistor R121 is connected to Zener diode ZD6, Zener diode ZD6 is connected to resistor R120; and resistor R98 is connected to pin 2 of optocoupler U2 and pin 1 of optocoupler U3.

[0027] Pin 2 of chip U1 is connected to capacitor C19, and capacitor C19 is connected to pin 3 of optocoupler U2 and pin 3 of optocoupler U3.

[0028] Resistor R120 is connected to resistor R96, resistor R96 is connected to Zener diode ZD5, Zener diode ZD5 is connected to resistor R97, and resistor R97 is connected to resistor R98.

[0029] Resistor R98 is connected to resistor R122, and resistor R122 is connected to pin 2 of optocoupler U2 and pin 1 of optocoupler U3.

[0030] Pin 2 of optocoupler U3 is connected to Zener diode ZD7 and capacitor C28.

[0031] like Figure 1 As shown:

[0032] The chip U1 is model CR6855, the optocouplers U2 and U3 are both model EL817, the capacitor C19 is 100pF / 50V, and the resistor R98 is 3KΩ.

[0033] Working principle:

[0034] This circuit uses a dual optocoupler control circuit. When pins 3 and 4 of optocoupler U2 are short-circuited, chip U1 can protect the power supply through FB feedback and control the primary MOS to turn off. The power supply has no output and will not cause other damage.

[0035] When pins 3 and 4 of optocoupler U2 are short-circuited, optocoupler U3 can still feed back to FB normally, thus not affecting the normal operation of the power supply.

[0036] When pins 1 and 2 are short-circuited, the feedback of pins 3 and 4 of optocoupler U2 fails, but the feedback can be provided normally through optocoupler U3.

[0037] When optocoupler U2 is open-circuited, the feedback from pins 3 and 4 of optocoupler fails, but feedback can still be provided normally through optocoupler U3. Power can be supplied to optocoupler U3 normally through resistor R98. Similarly, when U3 fails, U2 can work normally. This effectively avoids damage to the power supply itself or other equipment and instruments, as well as safety accidents, caused by the failure of a single component.

[0038] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual optocoupler protection circuit, comprising chip U1, optocoupler U2, and optocoupler U3, characterized in that: The FB terminal of the chip U1 is connected to pin 4 of the optocoupler U2 and pin 4 of the optocoupler U3; Pin 3 of the optocoupler U2 is connected to pin 3 of the optocoupler U3; Pin 2 of the optocoupler U2 is connected to pin 1 of the optocoupler U3; Pin 1 of the optocoupler U2 is connected to resistors R121 and R98. Resistor R121 is connected to Zener diode ZD6, and Zener diode ZD6 is connected to resistor R120. The resistor R98 is connected to pin 2 of optocoupler U2 and pin 1 of optocoupler U3.

2. The dual optocoupler protection circuit according to claim 1, characterized in that: The chip U1 is model number CR6855.

3. The dual optical coupling protection circuit of claim 1, wherein: The optocouplers U2 and U3 are both EL817.

4. The dual optocoupler protection circuit according to claim 1, characterized in that: The second pin of the chip U1 is connected to capacitor C19, which has a specification of 100pF / 50V.

5. A dual optical coupling protection circuit according to claim 4, wherein: The capacitor C19 is connected to pin 3 of optocoupler U2 and pin 3 of optocoupler U3.

6. The dual optical coupling protection circuit of claim 1, wherein: The resistor R98 has a specification of 3KΩ.

7. The dual optical coupling protection circuit of claim 1, wherein: The resistor R120 is connected to the resistor R96, the resistor R96 is connected to the Zener diode ZD5, the Zener diode ZD5 is connected to the resistor R97, and the resistor R97 is connected to the resistor R98.

8. A dual optical coupling protection circuit according to claim 7, wherein: The resistor R98 is connected to the resistor R122, and the resistor R122 is connected to pin 2 of the optocoupler U2 and pin 1 of the optocoupler U3.

9. A dual optical coupling protection circuit according to claim 8, wherein: Pin 2 of the optocoupler U3 is connected to Zener diode ZD7 and capacitor C28.

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