Control circuit for power supply AC input overvoltage protection

Abstract

The utility model discloses a control circuit for power supply AC input overvoltage protection, which comprises a three-terminal voltage stabilizer U6, a first terminal of the three-terminal voltage stabilizer U6 is respectively connected with a resistor R3 and a resistor R52, a third terminal of the three-terminal voltage stabilizer U6 is connected with a resistor R5, the other terminal of the resistor R5 is connected with a B terminal of a triode amplifier Q5, a C terminal of the triode amplifier Q5 is connected with a resistor R6, and the other terminal of the triode amplifier Q5 is connected with the resistor R6. The control circuit for the AC input overvoltage protection of the power supply has the advantages of few elements, low cost and relatively accurate set limit voltage, can be easily applied to an external consumer power adapter or a bare board of a built-in switching power supply, and can be conveniently added; the input alternating current is converted into the limited optimal input working voltage of the product, the working mode that the reference voltage of the three-terminal voltage stabilizer is connected or disconnected with the triode amplifier is adopted, the potential of the power supply chip VCC is lowered through triode connection, the power supply work of the power supply VCC is stopped, and the power supply product is protected.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply protection circuits, in particular to a control circuit for power supply AC input overvoltage protection. Background Art

[0002] With the improvement of living standards, electrical products are widely used, and large and small power supplies are equipped in electrical products. There are also some overvoltage protection circuits at present. However, after trial, although the products are not damaged, there are always some unsatisfactory things. For example, some overvoltage protection will be provided, but when the voltage is restored, the product cannot resume working and needs to be restarted; some are in a choking state, causing the product to keep working but not work.

[0003] Because some products are connected to the mains, the voltage may change suddenly due to the power grid. In order to protect electrical products from being damaged by high power grid voltage, a protection control circuit that limits excessive input voltage is added to the switching power supply. Utility Model Content

[0004] The main purpose of the utility model is to provide a control circuit for power supply AC input overvoltage protection, which can effectively solve the problems in the background technology.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A control circuit for power supply AC input overvoltage protection includes a three-terminal regulator U6, wherein one end of the three-terminal regulator U6 is respectively connected to a resistor R3 and a resistor R52, and the other end of the three-terminal regulator U6 is connected to a resistor R5, and the other end of the resistor R5 is connected to the B end of a transistor amplifier Q5.

[0007] As a preferred control circuit for power supply AC input overvoltage protection of the utility model, the C terminal of the transistor amplifier Q5 is connected to the resistor R6, and the E terminal of the transistor amplifier Q5 is connected to the resistor R4.

[0008] As a preferred control circuit for power supply AC input overvoltage protection of the utility model, the other end of the resistor R52 is connected to the resistor R54, and the other end of the resistor R54 is connected to the AC voltage.

[0009] As a preferred control circuit of a power supply AC input overvoltage protection of the utility model, the other end of the resistor R6, two ends of the three-terminal regulator U6 and the other end of the resistor R3 intersect at a grounding circuit.

[0010] As a preferred embodiment of the control circuit for AC input overvoltage protection of the utility model, the other end of the resistor R4 is connected to the VCC voltage.

[0011] Compared with the prior art, the utility model has the following beneficial effects:

[0012] The control circuit of the power supply AC input overvoltage protection has few components and low cost in design. The setting limit voltage is relatively accurate. It is easy to apply to external consumer power adapters or use built-in switching power supply bare boards. It is very convenient to add this circuit. By converting the input AC power into the optimal input operating voltage of the product we limit, and through the reference voltage of the three-terminal regulator and the working mode of the transistor amplifier on or off, the transistor is turned on to lower the VCC potential of the power chip, stop the power supply VCC power supply work, and protect the power supply product. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a circuit schematic diagram of a control circuit for power supply AC input overvoltage protection in Example 1 of the utility model;

[0014] Figure 2 This is a flow chart of a control circuit for power supply AC input overvoltage protection in Example 1 of the utility model. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0016] Example 1

[0017] like Figure 1-2 As shown, a control circuit for power supply AC input overvoltage protection includes a three-terminal regulator U6, wherein terminal 1 of the three-terminal regulator U6 is respectively connected to resistor R3 and resistor R52, terminal 3 of the three-terminal regulator U6 is connected to resistor R5, and the other end of the resistor R5 is connected to terminal B of the transistor amplifier Q5.

[0018] The C terminal of the transistor amplifier Q5 is connected to the resistor R6, and the E terminal of the transistor amplifier Q5 is connected to the resistor R4.

[0019] The other end of the resistor R52 is connected to the resistor R54, and the other end of the resistor R54 is connected to the AC voltage.

[0020] The other end of the resistor R6, two ends of the three-terminal regulator U6 and the other end of the resistor R3 are connected to the ground line.

[0021] The other end of the resistor R4 is connected to the VCC voltage.

[0022] When used specifically, this circuit has few components and low cost. The limited voltage setting is relatively accurate, and it is easy to apply to an external consumer power adapter or a bare board using a built-in switching power supply. It is very convenient to add this circuit. By converting the input AC power into the optimal input operating voltage of the product we limit, and through the reference voltage of the three-terminal regulator and the working mode of the transistor amplifier being turned on or off, the VCC potential of the power chip is lowered by the transistor conduction, the power supply of the power supply VCC is stopped, and the power supply product is protected.

[0023] Working principle: When the AC voltage is limited to 240V, when the AC voltage of the mains reaches 240V, the voltage after rectification also reaches the limit. When the voltage at the upper end of R3 is greater than the reference voltage of U6 2.5V after the voltage is divided by resistors R54, R52 and R3, U6 is turned on, Q5 is turned on, and the power supply IC, VCC voltage is pulled down to below the VCC working voltage. The power supply chip VCC stops working because the power supply voltage is too low, thereby shutting off the output and the switching power supply enters protection. When the mains voltage returns to below 240VAC, when the potential of U6's 1st pin is lower than 2.5V after the voltage is divided by R54, R52 and R3, U6 is not connected, and Q5 is cut off at the same time, ensuring that the power supply VCC returns to normal and the product works normally.

[0024] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. A control circuit for AC input overvoltage protection of a power supply, comprising a three-terminal voltage regulator U6, characterized in that: Terminal 1 of the three-terminal regulator U6 is connected to resistor R3 and resistor R52 respectively, terminal 3 of the three-terminal regulator U6 is connected to resistor R5, and the other end of resistor R5 is connected to terminal B of transistor amplifier Q5.

2. A control circuit for AC input overvoltage protection of a power supply according to claim 1, characterized in that: The C terminal of the transistor amplifier Q5 is connected to the resistor R6, and the E terminal of the transistor amplifier Q5 is connected to the resistor R4.

3. The control circuit for AC input overvoltage protection of a power supply according to claim 1, characterized in that: The other end of the resistor R52 is connected to the resistor R54, and the other end of the resistor R54 is connected to the AC voltage.

4. A control circuit for AC input overvoltage protection of a power supply according to claim 2, characterized in that: The other end of the resistor R6, two ends of the three-terminal voltage regulator U6 and the other end of the resistor R3 are connected to the ground line.

5. The control circuit for AC input overvoltage protection of a power supply according to claim 1, characterized in that: The other end of the resistor R4 is connected to the VCC voltage.

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