CN211908672U - Switch power supply - Google Patents

Abstract

The utility model discloses a switching power supply relates to switching power supply's technical field, and its technical scheme's main points are: including power generation circuit, connect rectifier circuit, voltage conversion circuit, switch control circuit and the load at power generation circuit output, its characterized in that: the power switch control circuit comprises a power chip connected to the output end of the voltage conversion circuit and an overcurrent protection circuit connected to the output end of the power chip, the output end of the overcurrent protection circuit is connected to the input end of the linear photoelectric coupler, and a normally open contact of the linear photoelectric coupler is connected with a load. The utility model provides a lead to transformer winding short circuit when falling into the foreign matter, perhaps high temperature causes the transformer magnetic saturation suddenly, and when secondary rectifier tube short circuit, the voltage of load surpasss its rated range easily and leads to the technical problem of damage, has and can in time break off the circuit, protection circuit's advantage after the above-mentioned anomaly appears in the circuit.

Description

a switching power supply

technical field

The utility model relates to the technical field of reagent detection, in particular to a switching power supply and an overcurrent protection circuit for the switching power supply.

Background technique

Switch mode power supply, also known as switching power supply and switching converter, is a high-frequency power conversion device and a type of power supply. Its function is to convert a level of voltage into the voltage or current required by the user through different forms of architecture. The input of the switching power supply is mostly AC power or DC power, and the output is mostly a device that requires DC power, such as a personal computer, and the switching power supply converts the voltage and current between the two.

The switching power supply in the prior art includes, referring to FIG. 1 , a current generation circuit, a rectifier circuit 2 connected to the output end of the current generation circuit, a voltage conversion circuit 3 , and a load circuit 5 connected to the output end of the voltage conversion circuit 3 . The output end is connected with the power switch control circuit 4, which is realized by the power chip IC1, the No. 2 pin of the power chip is connected with one end of the linear optocoupler, the other end of the linear optocoupler is grounded, and the linear optocoupler The normally open contacts are connected in the load circuit 5.

In the prior art, the power chip of the switching power supply has a resistor and capacitor in use to prevent misoperation. When a foreign object is dropped, the transformer winding is short-circuited, or the transformer is suddenly magnetically saturated due to high temperature, and the secondary rectifier is short-circuited, the voltage of the load is easily Exceeding its rated range can cause damage.

Utility model content

The purpose of the utility model is to provide a switching power supply and an overcurrent protection circuit for the switching power supply, which has the advantage of protecting the circuit when the current in the circuit increases.

The above technical purpose is achieved through the following technical solutions, a switching power supply, including a power generation circuit, a rectifier circuit connected to the output end of the power generation circuit, a voltage conversion circuit, a power switch control circuit, and a load, and the power switch control circuit includes a connection. The power supply chip at the output end of the voltage conversion circuit, and the overcurrent protection circuit connected to the output end of the power supply chip, the output end of the overcurrent protection circuit is connected to the input end of the linear optocoupler, and the normally open contact of the linear optocoupler point is connected to the load.

Through the above technical solution, the mains power is connected through the power generation circuit, the switching power supply is formed through the switch control circuit after passing through the rectifier circuit, and after the setting of the protection circuit, when the current is too high, the protection circuit pulls down the current at the input end of the linear optocoupler to turn the circuit disconnected to protect the circuit.

Further, the overcurrent protection circuit includes a reference chip IC3, the reference chip IC3 has two input ends A1 and A2, and an output end B, the input end A1 of the reference chip IC3 is connected to the output end of the rectifier circuit, the reference The input end A2 of the chip IC3 is connected to the input end of the linear optocoupler, and the input end A2 of the reference chip IC3 is connected to the input end of the linear optocoupler.

Through the above technical solution, the feedback input pin of the power supply chip is used to control the switch of the linear optocoupler, and the output end of the reference chip is connected to the input end of the light-emitting end in the linear optocoupler, so as to control the conduction of the switch end of the linear optocoupler. When the current of the base stage of the reference chip TO-92 is large, the input end of the linear photocoupler is pulled down, and the current is disconnected to realize the protection of the circuit.

Further, the overcurrent protection circuit includes a comparator U1 whose one end is connected to the 6th pin of the power chip IC1, the reverse input end of the comparator U1 is connected to the 6th pin of the power chip IC1, and the forward direction of the comparator U1. The input terminal provides the reference through the reference chip IC3.

Further, the forward input end of the comparator U1 is connected to one end of the resistor R0, the other end of the resistor R0 is connected to the power supply VCC, the forward input end of the comparator U1 is connected to the reference chip IC3, and the reference chip IC3 The input terminal A1 is connected between the resistor R0 and the positive input terminal of the comparator U1, the input terminal A1 of the reference chip IC3 is connected to the input terminal A2 of the reference chip IC3, the output terminal B2 of the reference chip IC3 is grounded, and the output of the comparator U1 The terminal is connected to pin 2 of the power chip IC1.

Through the above technical solution, the comparator compares the signal size of the reference chip, and when the signal is higher than the signal set by the reference chip, the load circuit can be disconnected by pulling down the voltage of the linear optocoupler.

Further, one end of the capacitor C27 is connected to the output end B1 of the reference chip IC3, and the other end of the capacitor C27 is grounded.

Further, the model of the reference chip IC3 is 431-TO-92.

Further, the model of IC3 of the reference chip is 431-TO-92.

Further, it includes an overcurrent protection circuit whose output end is connected to the input end of the linear optocoupler, the normally open contact of the linear optocoupler is connected to the load, and the overcurrent protection circuit includes a No. 6 lead connected to the power chip. The comparator U1 of the pin, the reverse input end of the comparator U1 is connected to the power chip IC1, the forward input end of the comparator U1 is connected to one end of the resistor R0, the other end of the resistor R0 is connected to the power supply VCC, the comparator U1 The forward input end of the reference chip IC3 is connected to the reference chip IC3, the input end A1 of the reference chip IC3 is connected between the resistor R0 and the forward input end of the comparator U1, the input end A1 of the reference chip IC3 and the input end A2 of the reference chip IC3 Connection, the output end B2 of the reference chip IC3 is grounded, and the output end of the comparator U1 is connected to the No. 2 pin of the power chip IC1.

In summary, the utility model has the following technical effects:

The mains is connected through the power generation circuit, and the switching power supply is formed through the switch control circuit after rectification by the rectifier circuit. Due to the setting of the overcurrent protection circuit, when the current is too high, the protection circuit pulls down the current at the input end of the linear optocoupler to cut off the circuit. On, it acts as a protection circuit. The feedback input pin of the power chip is used to control the switch of the linear optocoupler, and the output end of the reference chip is connected to the input end of the light-emitting end in the linear optocoupler, which can control the linear optocoupler. When the current of the base level of the reference chip TO-92 is large, the input end of the linear photocoupler is pulled down, and the current is disconnected from the switch to realize the protection of the circuit.

Description of drawings

1 is a circuit diagram of the background technology;

2 is a circuit diagram of Embodiment 1;

FIG. 3 is a circuit diagram of Embodiment 2. FIG.

Reference numerals: 1. Power generating circuit; 2. Rectifying circuit; 3. Voltage conversion circuit; 4. Switch control circuit; 40. Overcurrent protection circuit; 5. Load circuit.

Detailed ways

Embodiment 1, a switching power supply, referring to FIG. 2, includes a power generation circuit 1, a rectifier circuit 2 connected to the output end of the power source generation circuit 1, a voltage conversion circuit 3 connected to the output end of the rectifier circuit 2, and a voltage conversion circuit 3. The output end of the load circuit 5, the input end of the voltage conversion circuit 3 is connected to the switch control circuit 4, the output end of the switch control circuit 4 is provided with a linear photocoupler, and the normally open contact of the linear photocoupler is connected in series in the load circuit 5.

The voltage conversion circuit 3 includes a transformer T1 connected to the output end of the rectifier circuit 2, and the switch control circuit 4 includes a power supply chip IC1 whose model is OB2269C. The number pin is connected to the input end of the linear optocoupler, and the power supply chip IC1 can control the linear optocoupler to get electricity, and the load can work normally.

The switch control circuit 4 is provided with an overcurrent protection circuit 40. The overcurrent protection circuit 40 includes a resistor R9 connected to pin 6 of the power chip IC1 at one end and a comparator U1 connected to the other end of the resistor R9. The phase input terminal is connected to the resistor R9, the positive input terminal of the comparator U1 is connected to one end of the resistor R0, the other end of the resistor R0 is connected to the power supply VCC, and the positive input terminal of the comparator U1 is connected to the reference chip IC3. The model of chip IC3 is 431-TO-92. The reference chip IC3 has two input terminals A1 and A2, and one output terminal B. The input terminal A1 of the reference chip IC3 is connected between the resistor R0 and the non-positive input terminal of the comparator U1. , the input end A2 of the reference chip IC3 is connected to the input end A1 of the reference chip IC3, and the output end B of the reference chip IC3 is grounded.

The output end A2 of the reference chip IC3 is connected to one end of the capacitor C27, and the other end of the capacitor C27 is grounded.

The output end of the comparator U1 is connected to the No. 2 pin of the power chip.

In the specific implementation process, when the comparator U1 detects that the output current of pin 6 of the power chip IC1 is low, it can be fed back from the output end of the comparator U1 to the input end of the linear optocoupler to pull the current down, The normally open contact of the linear optocoupler is disconnected, thereby protecting the circuit.

Embodiment 2, a switching power supply, referring to FIG. 3 , the difference between this embodiment and Embodiment 1 is that the overcurrent protection circuit 40 includes a resistor R9 whose one end is connected to pin 6 of the power chip IC1, and the other end of the resistor R9 One end of the resistor R8 is connected, the other end of the resistor 8 is grounded, one end of the resistor RX is connected between the resistor R8 and the resistor R9, and the other end of the resistor RX is connected with the reference chip IC3, the model of the reference chip IC3 is 431-TO-92, The reference chip IC3 has an input terminal A and two output terminals B1 and B2. The input terminal A of the reference chip IC3 is connected to the No. 2 pin of the power supply chip IC1. The output terminal B1 of the reference chip IC3 is connected to the resistor R8. The reference chip IC3 The output terminal B2 of the reference chip IC3 is grounded, the positive terminal of the capacitor C28 is connected between the input terminal A of the reference chip IC3 and the No. 2 pin of the power chip IC1, and the negative terminal of the C28 is grounded.

In the specific implementation process, when the output terminal B1 of the reference chip IC3 detects that the current of the primary circle of the transformer T1 is too large, the reference chip IC3 pulls the current down to reduce the current at the input end of the linear optocoupler, so that the linear optoelectronic The coupler loses power, which can de-energize the load, thereby protecting the circuit.

This specific embodiment is only an explanation of the present utility model, and it is not a limitation of the present utility model. Those skilled in the art can make modifications to the present embodiment without creative contribution as needed after reading this specification, but as long as the utility model is used in the present invention All new types of claims are protected by the patent law.

Claims (7)

1. A switching power supply, comprising a power generation circuit (1), a rectifier circuit (2) connected to an output end of the power generation circuit (1), a voltage conversion circuit (3), a power switch control circuit (4) and a load, wherein The power switch control circuit (4) includes a power supply chip connected to the output end of the voltage conversion circuit (3), and an overcurrent protection circuit connected to the output end of the power supply chip, and the output end of the overcurrent protection circuit is connected to the linear photoelectric The input end of the coupler, the normally open contact of the linear optocoupler is connected with the load. 2. A switching power supply according to claim 1, characterized in that: the overcurrent protection circuit (40) comprises a reference chip IC3, and the reference chip IC3 has two input ends A1 and A2, and an output end B, The input end A1 of the reference chip IC3 is connected to the output end of the rectifier circuit (2), the input end A2 of the reference chip IC3 is connected to the input end of the linear photocoupler, and the input end A2 of the reference chip IC3 is connected to the linear photoelectric coupler. input. 3. A switching power supply according to claim 1, characterized in that: the overcurrent protection circuit (40) comprises a comparator U1 whose one end is connected to pin No. 6 of the power supply chip IC1, and the reverse input end of the comparator U1 Connected to pin 6 of the power chip IC1, the positive input end of the comparator U1 provides a reference through the reference chip IC3. 4. A switching power supply according to claim 3, characterized in that: the positive input end of the comparator U1 is connected to one end of the resistor R0, the other end of the resistor R0 is connected to the power supply VCC, and the comparator U1 The forward input end is connected to the reference chip IC3, the input end A1 of the reference chip IC3 is connected between the resistor R0 and the forward input end of the comparator U1, the input end A1 of the reference chip IC3 is connected to the input end A2 of the reference chip IC3 , the output end B2 of the reference chip IC3 is grounded, and the output end of the comparator U1 is connected to the No. 2 pin of the power chip IC1. 5 . The switching power supply according to claim 4 , wherein the output terminal B1 of the reference chip IC3 is connected to one end of the capacitor C27 , and the other end of the capacitor C27 is grounded. 6 . 6 . The switching power supply according to claim 4 , wherein the model of the reference chip IC3 is 431-TO-92. 7 . 7. A switching power supply according to claim 2, wherein the IC3 model of the reference chip is 431-TO-92.

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