Power supply reverse connection prevention circuit for cooling fan and cooling fan

Abstract

The utility model discloses a power supply anti-reverse-connection circuit for a heat dissipation fan and the heat dissipation fan, and relates to the technical field of power supply anti-reverse-connection, the power supply anti-reverse-connection circuit comprises an MOS tube, a first capacitor, a first divider resistor and a second divider resistor; the grid electrode of the MOS tube is connected with one end of the first capacitor, and the grid electrode of the MOS tube is also connected with the other end of the first divider resistor and one end of the second divider resistor; the source electrode of the MOS tube is connected with the other end of the first capacitor, and the source electrode of the MOS tube is also connected with the other end of the second divider resistor. According to the utility model, reverse current generated during reverse connection of a power supply can be cut off, components in the circuit are protected, and the problem of electromagnetic compatibility caused by harmonic oscillation of the circuit due to fluctuation of voltage and current generated by using a diode is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply reverse connection prevention, in particular to a power supply reverse connection prevention circuit for a cooling fan and a cooling fan. Background Art

[0002] In the circuit powered by a DC power supply for a cooling fan, reverse connection prevention circuits are usually provided at the positive and negative input terminals of the power supply. The traditional method is to connect an anti-reverse diode in series in the input line. When the positive and negative power supplies of the power supply are connected reversely, the diode bears most of the voltage drop of the power supply.

[0003] Since the diode has a forward voltage drop, when the DC supply current is large, the power consumption is also large, which also brings the problem of heat generation of the diode due to temperature rise. In addition, since the conduction voltage drop of the diode also increases with the increase of the load current consumption, the subsequent power supply voltage fluctuates with the change of the load current.

[0004] Using a diode for reverse connection prevention has voltage and current fluctuations, resulting in harmonic oscillations in the circuit, thus bringing electromagnetic compatibility problems; not taking reverse connection prevention measures will damage the load circuit due to the reverse connection of the positive and negative poles of the power supply. Summary of the Utility Model

[0005] The technical problem to be solved by the utility model is aimed at the deficiencies of the prior art. Specifically, for the problems of damage to the load circuit caused by reversing the positive and negative poles of the load circuit and harmonic oscillations and electromagnetic compatibility caused by reverse connection of the diode in the circuit, the utility model specifically provides a power supply reverse connection prevention circuit for a cooling fan and a cooling fan, as follows:

[0006] 1) In the first aspect, the utility model provides a power supply reverse connection prevention circuit for a cooling fan, and the specific technical solution is as follows: including: an MOS transistor, a first capacitor, a first voltage dividing resistor, and a second voltage dividing resistor;

[0007] One end of the gate of the MOS transistor is connected to one end of the first capacitor, and the gate of the MOS transistor is also connected to the other end of the first voltage dividing resistor and one end of the second voltage dividing resistor; the source of the MOS transistor is connected to the other end of the first capacitor, and the source of the MOS transistor is also connected to the other end of the second voltage dividing resistor.

[0008] The beneficial effects of a power supply reverse connection prevention circuit for a cooling fan provided by the utility model are as follows:

[0009] By connecting a MOS transistor in the circuit, the reverse current generated when the power supply is connected reversely is cut off, protecting the components in the circuit and avoiding the voltage and current fluctuations caused by using a diode, which may lead to harmonic oscillation in the circuit and thus cause electromagnetic compatibility problems. At the same time, through the voltage division of the first voltage-dividing resistor and the second voltage-dividing resistor, a conduction voltage is provided for the gate of the MOS transistor, short-circuiting its parasitic diode, thereby greatly reducing the voltage drop and power consumption between the negative terminal of the load and the negative terminal of the power supply.

[0010] Based on the above solution, the present utility model can be further improved as follows.

[0011] Further, the other end of the second voltage-dividing resistor is also connected to the ground wire.

[0012] Further, one end of the first voltage-dividing resistor is connected to the input end of the load circuit.

[0013] Further, the other end of the second voltage-dividing resistor is also connected to the output end of the load circuit.

[0014] Further, an anti-static tube is further included. One end of the anti-static tube is connected to one end of the first voltage-dividing resistor, and the other end of the anti-static tube is connected to the drain of the MOS transistor.

[0015] Further, a lightning protection tube is further included. One end of the lightning protection tube is connected to one end of the first voltage-dividing resistor, and the other end of the lightning protection tube is connected to the drain of the MOS transistor.

[0016] 2) In the second aspect, the present utility model further provides a cooling fan, which uses a power supply reverse connection prevention circuit for a cooling fan as described in any one of the first aspect.

[0017] It should be noted that for the beneficial effects obtained by the technical solution of the second aspect of the present utility model and its corresponding possible implementation manners, reference can be made to the above technical effects of the first aspect and its corresponding possible implementation manners, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects, and advantages of the present utility model will become more apparent:

[0019] Figure 1 Schematic diagram of a power supply reverse connection prevention circuit for a cooling fan provided by an embodiment of the present utility model;

[0020] Figure 2 Schematic diagram of a protection circuit provided by an embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] To make the objectives, technical solutions and advantages of the present utility model clearer, the embodiments of the present utility model will be further described in detail below with reference to the accompanying drawings.

[0022] As Figure 1 shown, a power supply reverse connection prevention circuit for a cooling fan according to an embodiment of the present utility model includes the following steps:

[0023] It includes: MOS transistor Q1, first capacitor C1, first voltage dividing resistor R1 and second voltage dividing resistor R2;

[0024] One end of the gate of MOS transistor Q1 is connected to one end of first capacitor C1. The gate of MOS transistor Q1 is also connected to the other end of first voltage dividing resistor R1 and one end of second voltage dividing resistor R2. The source of MOS transistor Q1 is connected to the other end of first capacitor C1. The source of MOS transistor Q1 is also connected to the other end of second voltage dividing resistor R2.

[0025] The beneficial effects of a power supply reverse connection prevention circuit for a cooling fan provided by the present utility model are as follows:

[0026] By connecting MOS transistor Q1 in the circuit, the reverse current generated during reverse power connection is cut off, protecting the components in the circuit and avoiding the voltage and current fluctuations caused by using a diode, which may lead to harmonic oscillation in the circuit and thus cause electromagnetic compatibility problems. At the same time, through the voltage division of first voltage dividing resistor R1 and second voltage dividing resistor R2, a conduction voltage is provided for the gate of MOS transistor Q1, short-circuiting its parasitic diode, thereby greatly reducing the voltage drop and power consumption between the negative end of the load and the negative end of the power supply.

[0027] One end of the gate of MOS transistor Q1 is connected to one end of first capacitor C1. The gate of MOS transistor Q1 is also connected to the other end of first voltage dividing resistor R1 and one end of second voltage dividing resistor R2. The source of MOS transistor Q1 is connected to the other end of first capacitor C1. The source of MOS transistor Q1 is also connected to the other end of second voltage dividing resistor R2. Among them:

[0028] MOS transistor Q1 refers to: MOSFET metal-oxide semiconductor field effect transistor. An NMOS transistor can be selected. Under normal use, an NMOS transistor is connected in series on the negative terminal line of the power supply (hereinafter referred to as the power supply negative terminal). Its drain is connected to the above-mentioned power supply negative terminal, the source is connected to the output terminal of the load circuit L, and the gate is connected to first voltage dividing resistor R1 and second voltage dividing resistor R2, and is connected to the positive terminal of the power supply under normal use (hereinafter referred to as the power supply positive terminal +V) through first voltage dividing resistor R1.

[0029] First voltage dividing resistor R1 and second voltage dividing resistor R2 perform voltage division on the gate of MOS transistor Q1. The form of using first voltage dividing resistor R1 and second voltage dividing resistor R2 for voltage division is a relatively optimal choice in MOS gate drive.

[0030] Further, the other end of the second voltage-dividing resistor R2 is also connected to the ground wire.

[0031] Further, one end of the first voltage-dividing resistor R1 is connected to the input end of the load circuit L.

[0032] Further, the other end of the second voltage-dividing resistor R2 is also connected to the output end of the load circuit L.

[0033] During the use of the circuit, when the power supply is not reversely connected, when the DC power supply is just powered on, the power supply current enters from the positive terminal +V of the power supply, passes through the load circuit L, flows into the source electrode of the MOS transistor Q1 from the negative terminal of the load circuit L, and finally returns to the negative terminal of the DC power supply through the parasitic diode of the MOS transistor Q1, forming a closed loop. At this time, a voltage drop is formed between the positive terminal +V of the power supply and the negative terminal of the load, and this voltage is equal to the voltage of the power supply minus the voltage drop of the parasitic diode of the MOS transistor Q1.

[0034] After the voltage is established, through the voltage division of the first voltage-dividing resistor R1 and the second resistor, a conduction voltage is provided for the gate of the MOS transistor Q1. Through the voltage division of the first voltage-dividing resistor R1 and the second voltage-dividing resistor R2, the MOS transistor Q1 will be saturated and turned on, providing a conduction voltage for the gate of the MOS transistor Q1, short-circuiting its parasitic diode, thereby greatly reducing the voltage drop and power consumption between the negative terminal of the load and the negative terminal of the power supply. By connecting a MOS transistor Q1 to the negative terminal of the power supply, the original diode reverse connection protection circuit is replaced, thus avoiding the problem that the conduction voltage drop of the diode increases as the load current consumption increases, resulting in the subsequent power supply voltage fluctuating with the change of the load current, causing harmonic oscillation in the circuit, and thus bringing electromagnetic compatibility problems.

[0035] The first capacitor C1 is used to slow down the turn-on and turn-off time of the MOS transistor Q1, preventing the MOS transistor Q1 from generating spike voltages and ripples on the input power supply due to too fast switching.

[0036] When the power supply voltage is reversely connected to the circuit board due to accident or negligence, the power supply current flows in from the negative terminal of the power supply, a weak current is reversely loaded onto the parasitic diode of the MOS transistor Q1, and then flows back to the positive terminal +V of the power supply through the load circuit L. At this time, since the parasitic diode of the MOS transistor Q1 is in the reverse connection state, most of the reverse voltage of the power supply falls between the drain and source of the MOS transistor Q1, cutting off the reverse current of the power supply and protecting the subsequent load circuit L.

[0037] Further, it also includes an anti-static tube D1. One end of the anti-static tube D1 is connected to one end of the first voltage-dividing resistor R1, and the other end of the anti-static tube D1 is connected to the drain of the MOS transistor Q1.

[0038] Wherein:

[0039] The anti-static tube is composed of two diodes, such asFigure 2 , two diodes are respectively labeled 1 and 2.

[0040] Further, it further includes a lightning protection tube. One end of the lightning protection tube G1 is connected to one end of the first voltage dividing resistor R1, and the other end of the lightning protection tube G1 is connected to the drain of the MOS transistor Q1.

[0041] Such as Figure 2 , which is a schematic diagram of the protection circuit provided by the embodiment of the present invention. For the convenience of introducing this embodiment, the positive and negative electrodes of the power supply in the figure are connected with an electrostatic protection tube D1 and a lightning protection tube G1. Specifically, the electrostatic protection tube or the lightning protection tube can be selected and used according to actual requirements.

[0042] By using the electrostatic protection tube or the lightning protection tube, the circuit is protected as a whole, the circuit safety is improved, and the circuit components are protected.

[0043] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, rather than to limit a specific order or sequence. Under appropriate circumstances, the order of use of similar objects can be interchanged so that the embodiments of this application described here can be implemented in an order other than the order shown or described.

[0044] The present invention also provides a cooling fan, which uses a power supply reverse connection protection circuit for a cooling fan as described in any one of the above.

[0045] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A power supply reverse connection protection circuit for a cooling fan, characterized in that: include: MOS tube, a first capacitor, a first voltage-dividing resistor and a second voltage-dividing resistor; The gate of the MOS tube is connected to one end of the first capacitor, and the gate of the MOS tube is also connected to the other end of the first voltage-dividing resistor and one end of the second voltage-dividing resistor; the source of the MOS tube is connected to the other end of the first capacitor, and the source of the MOS tube is also connected to the other end of the second voltage-dividing resistor.

2. A power supply reverse connection protection circuit for a cooling fan according to claim 1, characterized in that: The other end of the second voltage-dividing resistor is also connected to the ground line.

3. A power supply reverse connection protection circuit for a cooling fan according to claim 2, characterized in that: One end of the first voltage-dividing resistor is connected to the input end of the load circuit.

4. A power supply reverse connection protection circuit for a cooling fan according to claim 3, characterized in that: The other end of the second voltage-dividing resistor is also connected to the output end of the load circuit.

5. A power supply reverse connection protection circuit for a cooling fan according to claim 1, characterized in that: It also includes an anti-static tube, one end of which is connected to one end of the first voltage-dividing resistor, and the other end of which is connected to the drain of the MOS tube.

6. A power supply reverse connection protection circuit for a cooling fan according to claim 1, characterized in that: It also includes a lightning protection tube, one end of which is connected to one end of the first voltage-dividing resistor, and the other end of which is connected to the drain of the MOS tube.

7. A cooling fan, characterized in that: A power reverse connection protection circuit for a cooling fan is used as claimed in any one of claims 1 to 6.

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