CN114792970A - Protection circuit for preventing reverse connection of power supply - Google Patents
Protection circuit for preventing reverse connection of power supply Download PDFInfo
- Publication number
- CN114792970A CN114792970A CN202110096392.6A CN202110096392A CN114792970A CN 114792970 A CN114792970 A CN 114792970A CN 202110096392 A CN202110096392 A CN 202110096392A CN 114792970 A CN114792970 A CN 114792970A
- Authority
- CN
- China
- Prior art keywords
- power supply
- field effect
- effect transistor
- channel field
- power
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
- H02H11/002—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
- H02H11/002—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection
- H02H11/003—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result in case of inverted polarity or connection; with switching for obtaining correct connection using a field effect transistor as protecting element in one of the supply lines
Abstract
The invention provides a power reverse connection prevention protection circuit (100), which can be used for timely switching off a circuit when a power is reversely connected, has low power consumption and small heat dissipation, and does not need to be provided with an additional power supply and the like. It comprises the following steps: the power supply reverse connection prevention module (4) is connected between the power supply (1) and the load (6); and the power supply reverse connection prevention module (4) comprises a first N-channel field effect transistor (41) and a reverse connection prevention discharge circuit (42), when the power supply (1) is connected positively, the voltage boosting circuit module (3) applies voltage to the grid electrode of the first N-channel field effect transistor (41) to enable the first N-channel field effect transistor to be conducted, so that the power supply (1) and the load (6) are switched on, when the power supply (1) is connected reversely, the reverse connection prevention discharge circuit (42) enables the voltage of the output end of the voltage boosting circuit module (3) to be released towards the power supply (1) and not applied to the grid electrode of the first N-channel field effect transistor (41), so that the first N-channel field effect transistor (41) is switched off, and the power supply (1) and the load (6) are switched off.
Description
Technical Field
The invention relates to a power-reverse-connection-prevention protection circuit, in particular to a power-reverse-connection-prevention protection circuit using an N field effect transistor with low power consumption.
Background
With the development of the automobile manufacturing industry, especially the popularization of electric automobiles, the safety of the vehicle-mounted battery as a power supply directly affects the safety performance of the whole automobile. In an electric vehicle, an on-board battery supplies power to an Electronic Control Unit (ECU), and if the positive terminal and the negative terminal of the on-board battery are reversed, that is, the power supply is reversed, various electronic components in the ECU are likely to be broken down or damaged due to voltage reversal. Moreover, when the power supply is reversely connected, the instantaneous current change may cause the vehicle-mounted battery to be burnt, and even more seriously, the vehicle-mounted battery also causes fire. If an operator is assembling or maintaining, dangerous situations such as electric shock of the operator may occur. Therefore, in order to ensure the safety performance of the vehicle-mounted battery, a protection circuit for preventing reverse connection of the power supply is generally provided in the electronic control unit.
The conventional circuit for protecting against reverse connection of power supply is to connect a diode, such as a schottky diode, in series with the positive electrode of the power supply to prevent the reverse connection of the power supply from affecting the power supply and its back circuit. However, the mode of connecting the diodes in series is only suitable for a low-power dc power supply, because the loss of the diodes increases with the increase of power, which seriously affects the efficiency of the power supply, and on the other hand, the heat generated by the voltage drop of the diodes increases, thereby causing the temperature of the whole power supply system to increase and the performance of each electronic component to decrease.
For high power supplies, P-MOSFETs (P-channel metal oxide semiconductor field effect transistors) are used in the prior art as an anti-reverse circuit in series to the positive supply electrode because P-MOSFETs have less losses compared to diodes. The P-MOSFET is expensive, the cost is high, the on-resistance of the P-MOSFET is high, and the heat generation amount increases with the increase of the current, which causes problems of heat dissipation and energy loss.
In contrast, patent document 1 proposes a dc input reverse connection prevention circuit based on N-MOSFETs (N-channel metal oxide semiconductor field effect transistors), in which an N-MOSFET Q2 is connected in series to a positive electrode bus J1-4 of a dc input, a gate of the N-MOSFET Q2 is driven by a gate drive circuit including a coupling inductor L1-D and a rectifier diode D3, and the coupling inductor L1-D is mutually inductively coupled to a coupling inductor L1-a of another power supply. Therefore, after the system is powered on and started, the N-MOSFET Q2 can be driven to be conducted, the on-resistance of the device is obviously reduced, the power loss generated in the case of large current is much smaller than that of a series diode scheme, and the influence on the normal operation of a circuit system is small. When the input polarity is reversed, the parasitic diode of the N-MOSFET Q2 is in a reverse off state, and the circuit system generally does not generate an effective drive to turn on the N-MOSFET Q2, thereby achieving the purpose of reverse polarity protection.
Documents of the prior art
Patent document
Patent document 1: CN206379724U
Disclosure of Invention
However, although the above patent document 1 reduces the on-resistance of the system and reduces the power consumption by using the N-MOSFET, the use of the inductive coupling circuit to connect to another ac power source to drive the gate of the N-MOSFET not only increases the overall size of the circuit but also complicates the circuit configuration, and the external ac power source is not suitable for a pure dc power source circuit.
Therefore, the technical problem to be solved by the present invention is to provide a power-reversal connection prevention protection circuit, which can meet the requirement of a high-power supply, reduce the cost, the power consumption and the heat productivity of the power supply circuit, can turn off the circuit in time when the power supply is reversed, has a high-efficiency protection effect, can also realize the miniaturization of the circuit structure, and does not need an external power supply, etc.
The invention discloses a power reverse connection prevention protection circuit, which comprises: the power supply reverse connection prevention module is connected between a power supply and a load; and a boost circuit module, the power supply reverse connection prevention module comprising: a first N-channel FET having a source connected to the power source and a drain connected to the load; and an anti-reverse-connection discharge circuit having one end connected to the power supply and the other end connected to the gate of the first N-channel fet, wherein the output end of the boost circuit module is connected to the gate of the first N-channel fet, and supplies a boosted voltage to the gate of the first N-channel fet, the power supply is grounded through a first capacitor, when the positive electrode of the power supply is connected to the source of the first N-channel fet, the boost circuit module applies the voltage to the gate of the first N-channel fet to turn on the first N-channel fet, so that the positive electrode of the power supply is connected to the load, and when the negative electrode of the power supply is connected to the source of the first N-channel fet, the anti-reverse-connection discharge circuit and the first capacitor form a discharge circuit that discharges in the direction of the power supply, the voltage of the output end of the booster circuit module is released to the direction of the power supply through the discharging loop without being applied to the grid electrode of the first N-channel field effect transistor, so that the first N-channel field effect transistor is cut off, and the negative electrode of the power supply is disconnected with the load.
In the power reverse connection prevention protection circuit of the present invention, preferably, the reverse connection prevention discharge circuit includes a second N-channel field effect transistor, a first resistor, and a second resistor, wherein a drain of the second N-channel field effect transistor is connected to the output terminal of the voltage boost circuit module, a source is connected to a source of the first N-channel field effect transistor through the first resistor, and a gate is grounded through the second resistor.
In the power reverse connection prevention protection circuit of the present invention, it is preferable that when a negative electrode of the power supply is connected to a source electrode of the first N-channel fet, the second N-channel fet is turned on, and a voltage at an output terminal of the booster circuit module is released in a direction of the power supply through a series circuit formed by the second N-channel fet and the first resistor, that is, the discharge circuit.
In the power reverse connection prevention protection circuit of the present invention, it is preferable that the power reverse connection prevention module further includes a voltage stabilizing circuit connected in parallel between an output terminal of the booster circuit module and a ground.
In the power reverse connection prevention protection circuit of the present invention, preferably, the voltage stabilizing circuit is formed by connecting a zener diode and a third resistor in series.
In the power reverse connection prevention protection circuit of the present invention, preferably, the booster circuit module includes: one end of the first inductor is used as the input end of the booster circuit module; the anode of the first diode is connected with the other end of the first inductor, and the cathode of the first diode is used as the output end of the booster circuit module; the second capacitor is connected between the output end of the booster circuit module and the ground in parallel; and the drain electrode is connected to the connection point of the first inductor and the first diode, the grid electrode receives the input of a control signal, and the source electrode of the third N-channel field effect transistor is grounded.
In the power reverse connection prevention protection circuit of the present invention, preferably, the first N-channel field effect transistor, the second N-channel field effect transistor, and the third N-channel field effect transistor are all N-channel Metal Oxide Semiconductor Field Effect Transistors (MOSFETs).
In the power-reversal-preventing protection circuit of the present invention, it is preferable that the first N-channel field effect transistor has a parasitic diode connected in parallel between the source and the drain.
In the power reverse connection prevention protection circuit of the present invention, it is preferable that a capacitance discharge coefficient of the first capacitor and a resistance value of the first resistor are set so as to shorten a discharge time of the discharge circuit.
In the power reverse connection prevention protection circuit of the present invention, it is preferable that the control module further includes a control module that outputs a control signal to a gate of the third N-channel fet of the booster circuit module, the control module includes a power IC and a cpu, a power input terminal of the power IC is connected to a drain of the first N-channel fet, the cpu is connected to the load, when an anode of the power is connected to a source of the first N-channel fet, the power IC outputs a voltage to the cpu to operate the cpu, the cpu outputs a control signal to a gate of the third N-channel fet to turn on the first N-channel fet, and when a cathode of the power is connected to the source of the first N-channel fet, the power IC, the cpu, and the booster circuit module all stop operating, and the first N-channel field effect transistor is cut off.
In the power reverse connection prevention protection circuit of the present invention, preferably, the control signal output by the central processing unit to the gate of the third N-channel fet is a pulse width modulation signal.
The power source reverse connection preventing protection circuit provided by the invention can meet the requirement of a high-power source, reduce the cost, reduce the power consumption, reduce the heat productivity of the power circuit, can timely turn off the circuit when the power source is reversely connected, has an efficient protection effect, can realize the miniaturization of a circuit structure, and does not need an external power source and the like.
Drawings
Fig. 1 is a functional block diagram of a power reverse connection preventing protection circuit 100 according to embodiment 1 of the present invention.
Fig. 2 is an exemplary circuit diagram of the power reverse connection preventing protection circuit 100 according to embodiment 1 of the present invention.
Fig. 3 is a timing chart of signals in the reverse power connection preventing protection circuit 100 according to embodiment 1 of the present invention when the power supply is connected in the forward direction and when the power supply is connected in the reverse direction.
Fig. 4 is a simulation circuit diagram of the power reverse connection prevention protection circuit 100 according to embodiment 1 of the present invention when the power is connected in the forward direction.
Fig. 5 is a graph showing a change in gate voltage of the N-MOSFET T1 in fig. 5.
Fig. 6 is a simulation circuit diagram of the power reverse connection prevention protection circuit 100 according to embodiment 1 of the present invention when the power is reversely connected.
Fig. 7 is a graph showing a change in gate voltage of the N-MOSFET T1 in fig. 6.
Fig. 8 is a functional block diagram of a power reverse connection prevention protection circuit 200 according to embodiment 2 of the present invention.
Fig. 9 is an exemplary circuit diagram of the power reverse connection preventing protection circuit 200 according to embodiment 2 of the present invention.
Detailed Description
The present invention is further described below in conjunction with the attached drawings and the detailed description so that those skilled in the art can better understand the present invention and can implement the present invention, but the embodiment is not limited to the present invention.
In embodiment 1, a case where the power reverse connection prevention protection circuit is applied to an electric vehicle will be described as an example. Referring to fig. 1 to 7, a power reverse connection prevention protection circuit 100 according to embodiment 1 of the present invention will be specifically described. Fig. 1 is a functional block diagram of the power reverse connection preventing protection circuit 100, fig. 2 is a specific circuit diagram thereof, fig. 3 is a timing diagram showing the power reverse connection preventing protection circuit 100 when the power is connected in the forward direction and when the power is connected in the reverse direction, fig. 4 and 5 are a simulation circuit diagram showing the power reverse connection preventing protection circuit 100 when the power is connected in the forward direction and a gate voltage variation diagram of the N-MOSFET T1, and fig. 6 and 7 are a simulation circuit diagram showing the power reverse connection preventing protection circuit 100 when the power is connected in the reverse direction and a gate voltage variation diagram of the N-MOSFET T1.
As shown in fig. 1, a power reverse connection preventing protection circuit 100 according to embodiment 1 of the present invention is mainly constituted by a booster circuit module 3 and a power reverse connection preventing module 4, wherein the booster circuit module 3 is connected to an ignition switch 2 and is controlled by a control module 5, the power reverse connection preventing module 4 is connected in series between a power supply 1 as an on-vehicle battery and a load 6 of a vehicle, and an output terminal of the power reverse connection preventing module 4 is also connected to the control module 5.
The power supply reverse connection prevention module 4 includes an N-channel field effect transistor (hereinafter referred to as an N-MOSFET)41 and a reverse connection prevention discharge circuit 42. When the power supply 1 is connected in the positive direction, that is, the positive electrode of the power supply 1 is connected to the N-MOSFET 41, the voltage boosting circuit module 3 outputs a voltage to the gate of the N-MOSFET 41 to turn on the circuit, so that the circuit operates normally, and the load 6 operates normally under the positive power supply of the power supply 1. When the power supply 1 is reversely connected, that is, the cathode of the power supply 1 is connected to the N-MOSFET 41, the N-MOSFET 41 is turned off, and at the same time, the voltage at the output end of the voltage boosting circuit module 3 is directly released towards the power supply 1 through the reverse connection preventing discharge circuit 42 without being applied to the gate of the N-MOSFET 41, so that the N-MOSFET 41 is ensured not to be turned on, thereby cutting off the connection between the cathode of the power supply 1 and the load 6, avoiding the load 6 from being broken down or even burned out when the power supply is reversely connected, and realizing the protection function of the reverse connection of the power supply.
Fig. 2 shows a specific circuit configuration of the power reverse connection preventing protection circuit 100 according to embodiment 1 of the present invention. The power supply 1 shown in fig. 2 corresponds to an in-vehicle battery, and outputs a dc voltage VBATT of, for example, 12V. The N-MOSFET T1 corresponds to the N-channel field effect transistor 41 in fig. 1, and the power supply IC (integrated circuit chip) 51 and the Central Processing Unit (CPU)52 constitute the control module 5 in fig. 1. The power supply IC 51 inputs a voltage VCC (e.g., 5V) to an input terminal of the CPU to start the CPU 51, and the CPU 51 is also connected to the load 7 via the drive IC 7.
The output of the power supply 1 is connected to the source of an N-MOSFET T1, while being connected to ground via a first capacitor C1. The drain of the N-MOSFET T1 is connected to the load 6 and also to the power input of the power IC 51. The N-MOSFET T1 is an N-channel field effect transistor with a parasitic diode connected in parallel between the source and drain. The gate of the N-MOSFET T1 is connected to the boost circuit block 3, and the boost circuit block 3 supplies a gate voltage to turn on or off.
The boost circuit module 3 includes a first inductor L1, a first diode D1, a second capacitor C2, and an N-MOSFET T2. One end of the first inductor L1 is connected to the ignition switch 2 and the wake-up (wakeup) terminal of the power supply IC 51, the other end is connected in series with the anode of the first diode D1, and the cathode of the first diode D1 is grounded via the second capacitor C2. The junction of the first inductor L1 and the first diode D1 is connected to the PWM (pulse width modulation) output of the CPU52 via an N-MOSFET T2. The drain of the N-MOSFET T2 is connected to the connection point, the source is grounded, and the gate is connected to the PWM output terminal of the CPU 52. The CPU52 controls the magnitude of the voltage output from the boosting circuit block 3 by adjusting the control signal output from the PWM output terminal to the gate of the N-MOSFET T2. The output terminal of the booster circuit block 3 (i.e., the terminal at which the cathode of the first diode D1 is located) is connected to the gate of the N-MOSFET T1 in the power supply reverse connection prevention block 4, and outputs the voltage Vout to the gate of the N-MOSFET T1. N-MOSFET T1 turns on when voltage Vout is above the gate threshold voltage of N-MOSFET T1, and N-MOSFET T1 turns off when voltage Vout is below the gate threshold voltage of N-MOSFET T1.
The power supply reverse connection prevention module 4 comprises an N-MOSFET T1, an N-MOSFET T3, a first resistor R1 and a second resistor R2. As described above, the N-MOSFET T1 is connected in series between the power supply 1 and the load 6, has its source connected to the power supply 1, its drain connected as an output terminal to the load 6 and to the power supply input terminal of the power supply IC 51, and its gate connected to the output terminal of the booster circuit module 3. The source of the N-MOSFET T1 is further connected to the source of the N-MOSFET T3 via a first resistor R1, the drain of the N-MOSFET T3 is connected to the output terminal of the voltage boost circuit module 3, and the gate of the N-MOSFET T3 is connected to the ground terminal of a second capacitor C2 in the voltage boost circuit module 3 via a second resistor R2. Thus, the N-MOSFET T3, the first resistor R1 and the second resistor R2 connected between the source of the N-MOSFET T1 and the output terminal of the booster circuit module 3 constitute the reverse-connection preventing discharge circuit 42 in fig. 1.
According to the power reverse connection prevention protection circuit 100 shown in fig. 2, when the positive electrode of the power source 1 is connected to the source of the N-MOSFET T1, that is, the source of the N-MOSFET T1 is applied with the positive voltage + VBATT, the booster circuit module 3 applies the voltage Vout higher than the gate threshold voltage thereof to the gate of the N-MOSFET T1 under the PWM control of the CPU52, the N-MOSFET T1 is turned on, thereby turning on the power source 1 and the load 6, and the circuit operates normally.
When the negative electrode of the power supply 1 is connected to the source of the N-MOSFET T1, that is, when the source of the N-MOSFET T1 is applied with the negative voltage-VBATT, the CPU52 stops controlling, and at the same time, the voltage generated by the electric charge accumulated across the second capacitor C2 in the booster circuit module 3 turns on the N-MOSFET T3, and the turned-on N-MOSFET T3, the first resistor R1, and the first capacitor C1 form a current release circuit, that is, a discharge circuit, and directly release the voltage across the second capacitor C2 toward the power supply 1 without being applied to the gate of the N-MOSFET T1. Therefore, the N-MOSFET T1 can not be conducted, the reverse power supply can be cut off in time, and the circuit abnormity is avoided.
Next, the operation of the power reverse connection preventing protection circuit 100 according to embodiment 1 of the present invention will be specifically described with reference to timing charts of signals when the power reverse connection preventing protection circuit 100 is connected to the power supply in the forward direction and in the reverse direction as shown in fig. 3.
Fig. 3 shows respective timing diagrams of the power supply voltage VBATT, the ignition switch, the wake-up signal, VCC, the PWM control signal, and the gate voltage T1.
When the power supply 1 is connected, the voltage outputted from the power supply 1, i.e. the power supply voltage VBATT, is a positive voltage, here, +12V is taken as an example.
At the timing when the ignition switch 2 is turned on (the signal goes to high level), the wake-up terminal of the power IC 51 is also turned on, and the wake-up signal inputted thereto also goes to high level. Then, the power supply IC 51 is awakened (activated), and the voltage VCC (here, 5V as an example) is input to the VCC input terminal of the CPU 52. Then, the CPU52 outputs a PWM control signal from the PWM output terminal to the booster circuit block 3, and the booster circuit block 3 outputs the voltage Vout to the gate of the N-MOSFET T1 based on the PWM control signal, and when the gate voltage of the N-MOSFET T1 exceeds the threshold voltage thereof as shown in the figure, the N-MOSFET T1 is turned on, the power source 1 and the load 6 are connected, and the circuit operates normally.
When the power supply 1 is reversely connected, the voltage outputted from the power supply 1, i.e. the power supply voltage VBATT, is a negative voltage, for example, -12V. As shown in fig. 3, the ignition switch, the wake-up signal, VCC, the PWM control signal, and the gate voltage of T1 all become low at the time T0 when the power supply 1 is reversely connected. Next, a specific operation of the power reverse connection prevention protection circuit 100 when the power is reversely connected will be described with reference to fig. 2 and 3.
At time T0, the output of the power supply 1, the supply voltage VBATT, changes from a positive voltage (e.g., +12V) to a negative voltage (e.g., -12V). At the same time, the signal of the ignition switch 2 is also changed from high level to low level (i.e., on → off), and thus the wake-up signal received by the wake-up terminal of the power supply IC 51 is also changed to low level, and therefore the VCC signal (5V) inputted to the VCC input terminal of the CPU52 by the power supply IC 51 is also changed to low level (0V), and the PMW output terminal of the CPU52 no longer outputs the pulse control signal, i.e., the PWM output is changed to low level. Since the signal of the ignition switch 2 is at low level and the gate of the N-MOSFET T2 is also inputted with low level, the N-MOSFET T2 is turned off, and the output terminal of the voltage boosting circuit block 3, i.e., the terminal connected to the gate of the N-MOSFET T1, generates a voltage (herein, denoted as V) due to the charge accumulated on the grounded second capacitor C2. Since the gate of the N-MOSFET T3 is connected to the ground terminal of the second capacitor C2 via the second resistor R2, the source thereof is connected to the output terminal of the power supply 1 (at this time, the negative voltage-VBATT) via the first resistor R1, and the drain thereof is connected to the output terminal of the voltage boost circuit module 3 having the voltage V, when the power supply 1 is reversely connected, the N-MOSFET T3 is turned on, the turned-on N-MOSFET T3 and the first resistor R1 form a discharge loop, so that the voltage V1 at both ends of the second capacitor C2 flows to the direction of the power supply 1 via the discharge loop and is grounded by the first capacitor C1 in the middle, thereby discharging the charges accumulated on the second capacitor C2, and avoiding the circuit elements from being damaged due to the negative voltage of the power supply 1 being applied to the N-MOSFET T1 to turn on. Thus, in fig. 3, at time T0 when the power supply 1 is reversely connected, the gate voltage of the N-MOSFET T1 also becomes 0.
The inventor also performs computer simulation on the power reverse connection prevention protection circuit 100 of the embodiment to further verify the technical effect. Fig. 4 and 6 show simulation circuit diagrams of the power reverse connection preventing protection circuit 100 when the power is connected in the forward direction and when the power is connected in the reverse direction, and fig. 5 and 7 show changes of the gate voltage of the N-MOSFET T1 when the power is connected in the forward direction and when the power is connected in the reverse direction, respectively.
As shown in fig. 4, a voltage V1 in the figure corresponds to a PWM output signal of the CPU52, a voltage V2 corresponds to a signal of the ignition switch 2 (12V shown in the figure), a voltage V3 corresponds to an output voltage of the power supply 1, and other configurations are substantially the same as those of the circuit diagram shown in fig. 2. As shown in fig. 5, when the power supply 1 is connected, the gate voltage of the N-MOSFET T1 (i.e. the output voltage of the voltage boost circuit block 3) stabilizes at 16V (the on voltage of the N-MOSFET T1) after a rising edge (about 50 μ s) from the voltage V2, i.e. the signal level 12V of the ignition switch 2, and then the N-MOSFET T1 is turned on, so that the circuit operates normally.
As shown in fig. 6, when the power supply 1 is reversely connected, since the N-MOSFET T2 is turned off, the illustration of the N-MOSFET T2 is omitted here as it is, and the illustration of the ground capacitance C1 in the vicinity of the power supply 1 is also omitted. The booster circuit module 3 becomes the voltage generated across the second capacitor C2 shown in fig. 6 as an output. At this time, since the N-MOSFET T3 is turned on, the discharge loop formed by the N-MOSFET T3 and the resistor R1 discharges the voltage across the second capacitor C2 directly to the direction of the power supply 1 (i.e., the direction opposite to the direction of the N-MOSFET T1) through the first capacitor C1. Thus, the gate of the N-MOSFET T1 is not applied with a voltage to turn it on, i.e., the N-MOSFET T1 is turned off. The change in the gate voltage of the N-MOSFET T1 is shown in fig. 7, which is directly reduced from the voltage at turn-on of 16V to 0V through a falling edge (about 40 s). Thus, it is ensured that the N-MOSFET T1 is not turned on when the power supply 1 is reversely connected, and that the connection between the reversely connected power supply 1 and the load 6 is timely turned off to protect the circuit elements from being damaged.
The illustrated data herein is merely an example. For example, in order to shorten the discharge time, i.e., the falling time of the gate voltage of the N-MOSFET T1 in fig. 7, the capacitor C1 with a large discharge coefficient and the resistor R1 with a large resistance value may be selected to achieve fast discharge, thereby shortening the time when the gate voltage of the N-MOSFET T1 is dropped to 0, and turning off the circuit more quickly for protection.
According to the power reverse connection prevention protection circuit 100 of the embodiment, the N-channel field effect transistor is connected in series between the power supply and the load, and the reverse connection prevention discharge circuit is connected between the grid of the N-channel field effect transistor and the booster circuit thereof, so that the normal operation of the circuit can be ensured when the power supply is in a positive connection state, and the circuit can be timely turned off without an external power supply and the like when the power supply is in a reverse connection state, thereby avoiding the circuit elements from being burnt down due to the reverse connection of the power supply.
Fig. 8 is a functional block diagram of the power reverse connection prevention protection circuit 200 according to embodiment 2 of the present invention, in which the load 6 is not shown. The basic configuration of fig. 8 is the same as that of the power-supply-reversal-preventing protection circuit 100 of embodiment 1 shown in fig. 1, except that a voltage stabilizing circuit 43 is further provided in the power supply reversal-preventing module 4, and the voltage stabilizing circuit 43 is connected in series between the voltage boosting circuit module 3 and the reversal-preventing discharge circuit 42.
Fig. 9 is an exemplary circuit diagram of the protection circuit 200 against reverse power connection. As shown in fig. 9, a voltage stabilizing circuit composed of a third resistor R3 and a zener diode Z1 is connected in parallel to two ends of the second capacitor C2, one end of the third resistor R3 is connected to the second resistor R2, the other end is connected to one end of the zener diode Z1, and the other end of the zener diode Z2 is connected to the output end of the voltage boost circuit module 3, i.e., the gate of the N-MOSFET T1. By using the voltage stabilizing circuit, when the power supply 1 is reversely connected, the voltage at the two ends of the second capacitor C2 is released to the cathode of the power supply 1 more stably through the N-MOSFET T3 and the discharge circuit of the first resistor R1, and the safety performance of the circuit is further ensured.
The series circuit formed by the third resistor R3 and the zener diode Z1 shown here is only one example of a voltage regulator circuit and may have other configurations.
The power reverse connection preventing protection circuit 200 according to embodiment 2 also achieves the same technical effects as those of the power reverse connection preventing protection circuit 100 according to embodiment 1. The N-channel field effect transistor is connected in series between a power supply and a load, and the reverse-connection preventing discharge circuit and the voltage stabilizing circuit are connected between the grid electrode of the N-channel field effect transistor and the booster circuit of the N-channel field effect transistor, so that the normal work of the circuit can be ensured when the power supply is connected positively, the circuit can be turned off in time without an external power supply and the like when the power supply is connected reversely, the burning of circuit elements caused by the reverse connection of the power supply is avoided, the structure is realized by utilizing the N-MOSFET, the heat productivity of the circuit can be reduced, and the cost can be reduced while the requirement of a high-power supply is met. On this basis, the voltage stabilizing circuit can make the discharge more stable and safer when the power supply is connected in reverse, and the protection circuit 200 for preventing the power supply from being connected in reverse in the embodiment 2 can further improve the protection function for preventing the power supply from being connected in reverse.
The above-described embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.
Claims (11)
1. A protection circuit against reverse connection of a power supply, comprising:
the power supply reverse connection prevention module is connected between a power supply and a load; and
a step-up circuit module for controlling the step-up circuit,
the power supply reverse connection prevention module comprises:
a first N-channel FET having a source connected to the power source and a drain connected to the load; and
an anti-reverse discharge circuit having one end connected to the power supply and the other end connected to the gate of the first N-channel FET,
the output end of the boosting circuit module is connected to the grid electrode of the first N-channel field effect transistor and provides boosted voltage for the grid electrode of the first N-channel field effect transistor,
the power supply is connected to ground via a first capacitor,
when the anode of the power supply is connected to the source electrode of the first N-channel field effect transistor, the voltage boosting circuit module applies the voltage to the grid electrode of the first N-channel field effect transistor to enable the first N-channel field effect transistor to be conducted, so that the anode of the power supply is connected with the load,
when the negative electrode of the power supply is connected to the source electrode of the first N-channel field effect transistor, the reverse connection preventing discharge circuit and the first capacitor form a discharge loop discharging towards the direction of the power supply, so that the voltage of the output end of the booster circuit module is released towards the direction of the power supply through the discharge loop and is not applied to the grid electrode of the first N-channel field effect transistor, the first N-channel field effect transistor is cut off, and the negative electrode of the power supply is disconnected with the load.
2. The reverse power protection circuit of claim 1,
the reverse connection preventing discharge circuit comprises a second N-channel field effect transistor, a first resistor and a second resistor,
the drain electrode of the second N-channel field effect transistor is connected to the output end of the booster circuit module, the source electrode of the second N-channel field effect transistor is connected to the source electrode of the first N-channel field effect transistor through the first resistor, and the grid electrode of the second N-channel field effect transistor is grounded through the second resistor.
3. The reverse power protection circuit of claim 2,
when the negative electrode of the power supply is connected to the source electrode of the first N-channel field effect transistor, the second N-channel field effect transistor is conducted, and the voltage of the output end of the booster circuit module is released towards the direction of the power supply through a series circuit formed by the second N-channel field effect transistor and the first resistor, namely the discharge loop.
4. The anti-power-reversal protection circuit of any of claims 1 to 3,
the power supply reverse connection prevention module is also provided with a voltage stabilizing circuit connected between the output end of the booster circuit module and the ground in parallel.
5. The protection circuit against power reversal of claim 4,
the voltage stabilizing circuit is formed by connecting a voltage stabilizing diode and a third resistor in series.
6. The anti-power-reversal protection circuit of any of claims 1 to 3,
the boost circuit module includes:
one end of the first inductor is used as the input end of the booster circuit module;
the anode of the first diode is connected with the other end of the first inductor, and the cathode of the first diode is used as the output end of the booster circuit module;
the second capacitor is connected between the output end of the booster circuit module and the ground in parallel; and
and the drain electrode of the third N-channel field effect transistor is connected to the connection point of the first inductor and the first diode, the grid electrode of the third N-channel field effect transistor receives the input of a control signal, and the source electrode of the third N-channel field effect transistor is grounded.
7. The reverse power protection circuit of claim 6,
the first N-channel field effect transistor, the second N-channel field effect transistor and the third N-channel field effect transistor are all N-channel Metal Oxide Semiconductor Field Effect Transistors (MOSFET).
8. The reverse power connection prevention protection circuit as claimed in any one of claims 1 to 3,
the first N-channel field effect transistor has a parasitic diode connected in parallel between a source and a drain.
9. The anti-power-reversal protection circuit of any of claims 1 to 3,
and setting the capacitance discharge coefficient of the first capacitor and the resistance value of the first resistor so as to shorten the discharge time of the discharge loop.
10. The reverse power connection prevention protection circuit as claimed in any one of claims 1 to 3,
the control module outputs a control signal to the grid electrode of the third N-channel field effect transistor of the booster circuit module,
the control module comprises a power supply IC and a central processing unit,
the power input end of the power supply IC is connected to the drain electrode of the first N-channel field effect transistor, the central processing unit is connected to the load,
when the positive electrode of the power supply is connected to the source electrode of the first N-channel field effect transistor, the power supply IC outputs voltage to the central processing unit to enable the central processing unit to work, the central processing unit outputs a control signal to the grid electrode of the third N-channel field effect transistor to enable the first N-channel field effect transistor to be conducted,
when the negative electrode of the power supply is connected to the source electrode of the first N-channel field effect transistor, the power supply IC, the central processing unit and the booster circuit module stop working, and the first N-channel field effect transistor is cut off.
11. The reverse power protection circuit of claim 10,
and the control signal output to the grid electrode of the third N-channel field effect transistor by the central processing unit is a pulse width modulation signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110096392.6A CN114792970A (en) | 2021-01-25 | 2021-01-25 | Protection circuit for preventing reverse connection of power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110096392.6A CN114792970A (en) | 2021-01-25 | 2021-01-25 | Protection circuit for preventing reverse connection of power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114792970A true CN114792970A (en) | 2022-07-26 |
Family
ID=82459833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110096392.6A Pending CN114792970A (en) | 2021-01-25 | 2021-01-25 | Protection circuit for preventing reverse connection of power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114792970A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115313345A (en) * | 2022-10-12 | 2022-11-08 | 成都新欣神风电子科技有限公司 | Reverse connection prevention protection circuit for direct-current power supply |
-
2021
- 2021-01-25 CN CN202110096392.6A patent/CN114792970A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115313345A (en) * | 2022-10-12 | 2022-11-08 | 成都新欣神风电子科技有限公司 | Reverse connection prevention protection circuit for direct-current power supply |
| CN115313345B (en) * | 2022-10-12 | 2023-01-10 | 成都新欣神风电子科技有限公司 | Reverse connection prevention protection circuit for direct-current power supply |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7257008B2 (en) | Start-up apparatus for power converters | |
| US6559689B1 (en) | Circuit providing a control voltage to a switch and including a capacitor | |
| US6812782B2 (en) | Switch mode converter that allows 100% duty cycle on gate driver | |
| US20060113980A1 (en) | Semiconductor integrated circuit for controlling power supply, an electronic component and a power supply device | |
| US7911192B2 (en) | High voltage power regulation using two power switches with low voltage transistors | |
| US7282809B2 (en) | Interface circuit between a direct-current voltage source and a circuit for driving a load, particularly for use in motor-vehicles | |
| US20110043955A1 (en) | Electrostatic discharge protection circuit, control method therefor, and switching regulator using same | |
| JP2007267537A (en) | Semiconductor integrated circuit and electronic system | |
| US20080203984A1 (en) | Step-up switching power supply device, and electronic device provided therewith | |
| US11569654B2 (en) | Power control device | |
| CN106253753B (en) | Semiconductor device with a plurality of semiconductor chips | |
| US6025705A (en) | DC-to-DC converter | |
| CN110635669A (en) | High-voltage MOSFET switch driving and protecting circuit | |
| EP2073385A2 (en) | Semiconductor output circuit for controlling power supply to a load | |
| US6700765B2 (en) | High current series-pass over-voltage protection circuit | |
| CN114792970A (en) | Protection circuit for preventing reverse connection of power supply | |
| KR20180046839A (en) | Driver circuit for the operation of a relay | |
| WO2013187269A1 (en) | Switching power source device | |
| US20130214754A1 (en) | Power supply device | |
| US7705547B2 (en) | High-side current sense hysteretic LED controller | |
| CN101567626A (en) | Electricity delivery system, method and electronic system | |
| US6856495B2 (en) | Series pass over-voltage protection circuit having low quiescent current draw | |
| US20100231188A1 (en) | Buck dc-to-dc converter and method | |
| US20220200458A1 (en) | Power supply for driving synchronous rectification elements of sepic converter | |
| JP2002093264A (en) | Contact damage preventing circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |