Switching power supply voltage abnormity detection circuit

Abstract

The utility model discloses a switching power supply voltage abnormity detection circuit which comprises an input port, a rectifier bridge, a voltage stabilizing device, an isolation device, a switching device and an output port. The input port is connected with the input end of the rectifier bridge, the output end of the rectifier bridge is connected with the input end of the isolation device through the voltage stabilizing device, the output end of the isolation device is connected with the output port through the switching device, and the output port is further connected with a main control chip of an external switching power supply; the beneficial effects of the utility model are that by using universal discrete devices which are common and easy to obtain in the market, the whole circuit is stable in structure and low in price; meanwhile, the voltage stabilizer can detect undervoltage, overvoltage or power-off functions of related voltage of the switching power supply, and optical coupler isolation is used, so that interference can be effectively avoided, and the reliability of signal transmission is also improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of switching power supply, specifically relates to a switching power supply voltage abnormality detection circuit. BACKGROUND

[0002] At present, the switching power supply input voltage detection circuit of existing switching power supply adopts the resistance-capacitance network to cooperate with the voltage division to the under-voltage function pin of the control chip, and the function is relatively single, and besides, the resistance-capacitance network is usually non-isolated design, and interference is easy to appear, thereby causing the reliability to reduce.Therefore, a kind of simple structure, reliable signal transmission solution is urgently needed. UTILITY MODEL CONTENTS

[0003] In view of the defects in the prior art, the utility model aims at providing a switching power supply voltage abnormality detection circuit to solve the technical problems proposed in the background art.

[0004] The utility model takes technical scheme as follows: a kind of switching power supply voltage abnormality detection circuit, including input port, rectifier bridge, voltage stabilizing device, isolating device, switching device and output port;

[0005] The input port is connected with the input end of the rectifier bridge, the output end of the rectifier bridge is connected with the input end of the isolating device through the voltage stabilizing device, the output end of the isolating device is connected with the output port through the switching device, and the output port is also connected with the main control chip of external switching power supply.

[0006] Preferably, the output end of the rectifier bridge is also connected with filter capacitor for generating smooth DC signal in parallel.

[0007] Preferably, the filter capacitor is also connected with discharging resistance for capacitor discharge in parallel.

[0008] Preferably, the switching power supply voltage abnormality detection circuit also includes current-limiting resistor for guaranteeing that current is within limit range, one end of the current-limiting resistor is connected with the output end of the rectifier bridge, one end of discharging resistance and one end of filter capacitor respectively, the other end of the current-limiting resistor is connected with the voltage stabilizing device, and the other end of the discharging resistance and the other end of filter capacitor are connected with ground respectively.

[0009] Preferably, the voltage stabilizing device adopts stabilizing tube.

[0010] Preferably, the isolating device adopts photo-coupler device, and the input end of the isolating device is also connected with voltage division resistance for fine tuning the voltage across diode in the photo-coupler device to reduce external interference.

[0011] Preferably, the switching device adopts triode.

[0012] The utility model discloses a beneficial effect lies in: the utility model provides a switching power supply voltage abnormality detection circuit, through using the general discrete device, the market common easy, make whole circuit structure stable, low price, simultaneously utilize the voltage stabilizing device can detect switching power supply related voltage under voltage, overvoltage or power off function, and use photoelectric coupler isolation, effectively avoid interference, also promote the reliability of signal transmission. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the specific embodiment of the utility model or the technical scheme in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiment or the prior art description. In all the drawings, similar elements or parts are generally identified by similar reference signs. In the drawings, the elements or parts are not necessarily drawn according to the actual proportion.

[0014] Figure 1 The utility model provides a switching power supply voltage abnormality detection circuit's connection schematic diagram for embodiment. DETAILED DESCRIPTION

[0015] The embodiments of the technical scheme of the present application will be described in detail below with reference to the drawings. The following examples are only used to more clearly illustrate the technical scheme of the present application, therefore only as an example, and cannot limit the protection scope of the present application.

[0016] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present application should be understood as the usual meaning understood by the skilled person in the field of the present application.

[0017] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0018] In addition, the terms "first", "second" and the like are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0019] In this application, unless otherwise clearly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0020] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present application should be understood as the usual meaning understood by those skilled in the art to which the present application belongs.

[0021] As shown in the Figure 1 , the switch power supply voltage abnormality detection circuit provided by the embodiment of the present application comprises an input port, a rectifier bridge, a voltage stabilizing device, an isolation device, a switching device and an output port;

[0022] The input port is connected with the input end of the rectifier bridge, the output end of the rectifier bridge is connected with the input end of the isolation device through the voltage stabilizing device, the output end of the isolation device is connected with the output port through the switching device, and the output port is further connected with the main control chip of the external switch power supply.

[0023] For the convenience of description, the input port is VIN1: input port 1 (not polarity) in Figure 1 , VIN2: input port 2 (not polarity); the rectifier bridge is represented by VD1; the voltage stabilizing device adopts a voltage stabilizing tube, and the voltage stabilizing device is represented by a voltage stabilizing tube VZ1; the isolation device is an optocoupler N1 in Figure 1 , and the pin definition of N1 is as follows: A: anode of diode, K: cathode of diode, C: collector of triode, E: emitter of triode; the switching device adopts a triode, and the switching device is VT1 (NPN type triode) in Figure 1 ; the output port is OUT: positive detection signal output, and SGND: negative detection signal output in Figure 1 .

[0024] In application, the output end of the rectifier bridge is further connected in parallel with a filter capacitor for generating a smooth direct current signal.

[0025] Specifically, the filter capacitor is a capacitor C1 in Figure 1 ; VD1 rectifies the alternating voltage signal into fluctuating direct current (direct current signal directly passes through), and then generates a smooth direct current signal through the filtering effect of the C1 capacitor.

[0026] In the embodiment, the filter capacitor is also connected in parallel with a discharging resistor for discharging the capacitor; the discharging resistor is denoted as R1, so as to ensure that the circuit can return to the initial no-electricity state in time.

[0027] In application, in order to improve reliability, the switch power supply voltage abnormality detection circuit further comprises a current limiting resistor for ensuring that the current is within a limited range, one end of the current limiting resistor is connected with the output end of the rectifier bridge, one end of the discharging resistor and one end of the filter capacitor respectively, the other end of the current limiting resistor is connected with the voltage stabilizing device, and the other end of the discharging resistor and the other end of the filter capacitor are both connected with the ground respectively.

[0028] The current limiting resistor is denoted as R2, and the current flowing through the diode in VZ1 and N1 is ensured to be within a limited range through the current limiting resistor.

[0029] In the embodiment, the isolating device adopts an optical coupling device, and a voltage dividing resistor for fine tuning the voltage across the diode in the optical coupling device is further connected in parallel with the input end of the isolating device, so as to reduce external interference; wherein the voltage dividing resistor is denoted as R3; the emitter of the triode in the optical coupling device is further connected with the base of VT1 through a resistor R4, the collector of the triode in the optical coupling device is further connected with VCC and the collector of VT1 respectively, and the emitter of VT1 is connected with the output port.

[0030] The working principle of the present application is as follows: in the technical solution, VD1 of the detection circuit rectifies the alternating voltage signal into a fluctuating direct current (direct current signal directly passes through), and then generates a smooth direct current signal through the filtering effect of C1 capacitor.

[0031] When the input voltage amplitude of the circuit is high enough, VZ1 will be broken down, the diode in N1 will be turned on, and then the triode in N1 will be in a low resistance state, so that the emitter of VT1 outputs a high level.

[0032] When the circuit is powered off or the voltage is not enough, the voltage signal will be cut off by VZ1, and the triode in N1 will be in a high resistance state, so that the emitter of VT1 has no output signal.

[0033] The above scheme uses common discrete devices, which are commonly available on the market, so that the entire circuit structure is stable and the price is low; at the same time, the voltage stabilizing device can detect the undervoltage, overvoltage or power-off function of the switch power supply related voltage, and the optical coupling isolation is used to effectively avoid interference and improve the reliability of signal transmission.

[0034] When applied, the scheme has low cost, simple structure and easily available materials, can be combined with a switching power supply circuit, directly incorporated into a power input or output, detect the generation of abnormal voltages such as under-voltage, over-voltage or power-off of the power related voltage, and reliably transmit signals through optical coupling isolation; at the same time, the circuit can also serve as an additional voltage monitoring function in the switching power supply, providing timely monitoring protection for the faulty power supply, and providing a good circuit foundation for product maintainability.

[0035] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application.

Claims

1. A switching power supply voltage abnormality detection circuit, characterized in that... The input port is connected with the input end of the rectifier bridge, the output end of the rectifier bridge is connected with the input end of the isolation device through the voltage stabilizing device, the output end of the isolation device is connected with the output port through the switching device, and the output port is also connected with the main control chip of the external switching power supply. The output end of the rectifier bridge is also connected with a filter capacitor for generating a smooth DC signal in parallel.

2. The switching power supply voltage abnormality detection circuit according to claim 1, characterized by The filter capacitor is also connected with a discharge resistor for capacitor discharge in parallel.

3. The switching power supply voltage abnormality detection circuit according to claim 2, characterized by The current limiting resistor is also connected with the output end of the rectifier bridge, one end of the discharge resistor and one end of the filter capacitor, respectively, and the other end of the current limiting resistor is connected with the voltage stabilizing device.

4. The switching power supply voltage abnormality detection circuit according to claim 3, characterized by The voltage stabilizing device adopts a voltage stabilizing tube.

5. The switching power supply voltage abnormality detection circuit according to any one of claims 1 to 4, characterized by The isolation device adopts an optical coupling device, and the input end of the isolation device is also connected with a voltage dividing resistor in parallel for fine tuning the voltage across the diode in the optical coupling device to reduce external interference.

6. The switching power supply voltage abnormality detection circuit according to claim 5, characterized by The switching device adopts a triode.

7. The switching power supply voltage abnormality detection circuit according to claim 6, characterized by ​

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