CN208479183U - A kind of lossless reversed polarity protection circuit structure - Google Patents

Abstract

The utility model discloses one kind while lossless reverse polarity protection's function is realized in perfection; reduce the static current consumption of product under high-line input voltage; and circuit components are further reduced, Material Cost is reduced, improves the lossless reversed polarity protection circuit structure of circuit reliability.It is to be connected on power supply negative pole end by power N-MOS pipe; the reverse polarity protection carried out by the on-off of metal-oxide-semiconductor; intelligent control of its driving control signal from single-chip microprocessor MCU; borrow that existing single-chip microcontroller in product circuit is under-voltage, control signals of overvoltage protection control circuits, to control anti-reverse N-MOS pipe；Its physical circuit connection relationship is as follows: it includes resistance R1, R2 and R3, capacitor C, inductance L, diode D and D1, triode PNP and NPN, field-effect tube Q and Q1, switching device SW, MCU single-chip microcontroller and boost driving chip.

Description

A kind of lossless reversed polarity protection circuit structure

Technical field

The utility model relates to a kind of reversed polarity protection circuits on vehicle-mounted start and stop regulated power supply class product, specifically Refer to a kind of in existing circuit function, by optimal control circuit, reduces circuit components while realizing defencive function, drop Low cost improves the lossless reversed polarity protection circuit structure of circuit reliability.

Background technique

General vehicle power supply class product is in order to meet the requirement of reversed polarity test item, it is necessary to design input reverse polarity protection Circuit.The design of input reversed polarity protection circuit, which is divided to, to be damaged and lossless two kinds.Damaging design is by fusing when input reversed polarity The fuse of power supply line protects product purpose to reach, and detailed annotation refers to the illustrative circuitry of attached drawing 1: automobile storage battery BATTERY mono- As after fuse FUSE power supply arrive the input terminal of product, the input terminal of usual product is placed a high-power TVS pipe, is used for 5b pulse voltage is absorbed, when inputting error-polarity connection, TVS pipe forward conduction generates big current loop, and high current flows through fuse FUSE makes FUSE fusing to cut off the input power supply of product and be protected.This design scheme cost is minimum, but due to that can damage Bad fuse will also confirm with main engine plants in advance, gradually be eliminated.And atraumatic design is additionally increased by interiors of products Power-up sub switch is protected, and when DC input voitage reversed polarity, electronic switch is not turned on, and current supply circuit is blocked, thus Realize protection, and guard period will not damage any device.

The increased electronic switch of lossless protection circuit is generally managed using power P-metal-oxide-semiconductor or N-MOS, it is contemplated that P-MOS pipe Often price is higher, at least 1 of N-MOS price times or more, and model is less, therefore enterprise can exclude power P-metal-oxide-semiconductor scheme, And directly select the scheme of power N-MOS pipe.The scheme of power N-MOS pipe also there are two types of, the first be connected on product input The positive terminal of power supply, detailed annotation refer to the illustrative circuitry of attached drawing 2: when inputting error-polarity connection, power N-MOS pipe Q is not turned on, and is blocked Current supply circuit is protected；But since N-MOS pipe is connected on anode, to controlling and opening N-MOS pipe, the control of gate foot Voltage necessarily is greater than input voltage B+, this, which is just additionally required, increases a bootstrap circuit boost, or need to use special control Chip Driver IC has virtually drawn high cost again.Occurs the scheme of second of optimization thus, by reversal connection N-MOS pipe series connection In the negative pole end of product input power supply, detailed annotation refers to the illustrative circuitry of attached drawing 3: since the body diode of N-MOS pipe Q is deposited , when inputting forward voltage, the body diode elder generation forward conduction of Q, B+ input power supply by divider resistance R1 and R2 establish Branch pressure voltage, and be given between the G and S of N-MOS pipe Q, open Q；The pressure resistance of the Vgs of inexpensive N-MOS pipe generally ± 20V has the test item of a long-time overvoltage, test voltage is more than 20V, to avoid N- for vehicle-mounted 12V system power supply The excessive pressure damages of metal-oxide-semiconductor Q, the parallel connection 15V voltage-stabiliser tube between Vgs, limits and the ceiling voltage of clamper Vgs is 15V.This scheme is worked as When inputting error-polarity connection, N-MOS pipe Q is not turned on, to effectively current supply circuit can also be blocked to be protected, but is still deposited It can not be ignored in some disadvantages, for example:

1, the power supply voltage range of general vehicle-mounted 12V system is 9~16V, in guaranteeing that N-MOS pipe is fully on, minimum It works in the state that resistance, maximum are resistant to flow, then it is best theoretically to wish 100% for the intrinsic standoff ratio of R1 and R2, but due to the limit of voltage-stabiliser tube The resistance value of leakage resistance can not be smaller, generally takes the rank of K Ω, parasitic capacitance will will will lead to pipe between the G-S of N-MOS pipe The opening speed of sub- Q is slower, during which if late-class circuit starting is fast, may have high current instantaneously to flow through Q, lead to the wind of failure Danger.

2, when input voltage is more than 15V, due to the effect of voltage-stabiliser tube, the quiescent current of input terminal will be unable to effectively control In the requirement of 0.1mA, quiescent dissipation will double.

In conclusion lacking a kind of while lossless reverse polarity protection's function is realized in perfection, the higher input of reduction at present The static current consumption of product under voltage can also reduce circuit components, reduce Material Cost, improve the reliability of circuit Lossless reversed polarity protection circuit structure.

Utility model content

The technical problems to be solved in the utility model is to provide a kind of in the same of the perfect lossless reverse polarity protection's function of realization When, the static current consumption of product under high-line input voltage is reduced, circuit components can also be reduced, Material Cost is reduced, mentions The lossless reversed polarity protection circuit structure of the reliability of high circuit.

In order to solve the above technical problems, technical solution provided by the utility model are as follows:

A kind of lossless reversed polarity protection circuit structure, it is to be connected on power supply negative pole end by power N-MOS pipe, passes through MOS The on-off of pipe carries out reverse polarity protection, and driving control signal borrows in product circuit from the intelligent control of single-chip microprocessor MCU Existing single-chip microcontroller is under-voltage, the control signal of overvoltage protection control circuits, to control anti-reverse N-MOS pipe；Its physical circuit connects It is as follows to connect relationship: it includes resistance R1, R2 and R3, capacitor C, inductance L, diode D and D1, triode PNP and NPN, field-effect Pipe Q and Q1, switching device SW, MCU single-chip microcontroller and boost driving chip；The MCU single-chip microcontroller voltage sample input terminal is successively By being connected after resistance R2, resistance R1 and FUSE with automobile storage battery anode, the enable signal output end and NPN tri- of MCU single-chip microcontroller The base stage of pole pipe is connected, and the emitter ground connection of NPN triode, the collector of NPN triode is connected with the base stage of PNP triode, The emitter of PNP triode is connected with the cathode of diode D1, the just extremely output end of circuit of diode D1；PNP triode Collector be connected to the VCC foot of boost driving chip and the G foot of N-MOS pipe Q simultaneously；The anode of automobile storage battery passes sequentially through The output end of circuit is connected to after fuse, inductance L and diode D；The bypass circuit of switching device SW composition and the left end inductance L It is in parallel with diode D1 right end；The drain D of N-channel field-effect tube Q is connected and is grounded with the cathode of automobile storage battery, field-effect tube There are a parasitic body diode, parallel resistance between the source S and grid G of field-effect tube Q between the source S and drain electrode of Q The grid G of R3, field-effect tube Q are extremely connected with the VCC of boost driving chip；The output end and field-effect tube of boost driving chip The grid of Q1 is connected, and the source electrode of field-effect tube Q1 is connected by capacitor C with the output end of circuit, the drain electrode connection of field-effect tube Q1 On node between inductance L and diode D.

Preferably, the MCU single-chip microcontroller model are as follows: S9KEAZN8A.

After adopting the above structure, the utility model has the following beneficial effects: when input voltage reversed polarity, reversed polarity is protected Shield N-MOS pipe blocks current supply circuit to be protected.When normal work, N-MOS pipe is opened simultaneously in boost booster circuit, when defeated When entering electric voltage over press, single-chip microcontroller meeting automatic identification simultaneously turns off N-MOS pipe, to guarantee that the Vgs pressure resistance of N-MOS pipe does not exceed mark ± the 20V claimed, does not need voltage-stabiliser tube clamping protective circuit in this way, saves component, do not increase circuit under high input voltage Quiescent dissipation, while the lasting pressure stabilizing working condition of voltage-stabiliser tube is avoided, improve the reliability of circuit.

In conclusion the utility model provides a kind of while lossless reverse polarity protection's function is realized in perfection, reduction The static current consumption of product under high-line input voltage can also reduce circuit components, reduce Material Cost, improve circuit The lossless reversed polarity protection circuit structure of reliability.

Detailed description of the invention

Fig. 1 is the reversed polarity protection circuit structural schematic diagram for damaging design in the prior art.

Fig. 2 is the reversed polarity protection circuit structural schematic diagram of the first atraumatic design in the prior art.

Fig. 3 is the reversed polarity protection circuit structural schematic diagram of second of atraumatic design in the prior art.

Fig. 4 is the structural schematic diagram of lossless reversed polarity protection circuit in the utility model.

Specific embodiment

The following describes the utility model in further detail with reference to the accompanying drawings.

In conjunction with attached drawing 4, a kind of lossless reversed polarity protection circuit structure, it is to be connected on power supply cathode by power N-MOS pipe End carries out reverse polarity protection by the on-off of metal-oxide-semiconductor, and control signal borrows product from the intelligent control of single-chip microprocessor MCU Existing single-chip microcontroller is under-voltage in circuit, control signals of overvoltage protection control circuits, to control anti-reverse N-MOS pipe；It is specific Circuit connecting relation is as follows: it includes resistance R1, R2 and R3, capacitor C, inductance L, diode D and D1, triode PNP and NPN, Field-effect tube Q and Q1, switching device SW, MCU single-chip microcontroller and boost driving chip；The MCU single-chip microcontroller voltage sample input End pass sequentially through resistance R2, resistance R1 and FUSE after be connected with automobile storage battery anode, the enable signal output end of MCU single-chip microcontroller and The base stage of NPN triode is connected, the emitter ground connection of NPN triode, the collector of NPN triode and the base stage of PNP triode It is connected, the emitter of PNP triode is connected with the cathode of diode D1, the just extremely output end of circuit of diode D1；PNP tri- The collector of pole pipe is connected to the VCC foot of boost driving chip and the G foot of N-MOS pipe Q simultaneously；The anode of automobile storage battery is successively By the output end for being connected to circuit after fuse, inductance L and diode D；The bypass circuit and inductance L of switching device SW composition Left end and diode D1 right end are in parallel；The drain D of N-channel field-effect tube Q is connected and is grounded with the cathode of automobile storage battery, field effect There should be a parasitic body diode between the source S and drain electrode of pipe Q, it is in parallel between the source S and grid G of field-effect tube Q The grid G of resistance R3, field-effect tube Q are extremely connected with the VCC of boost driving chip；The output end of boost driving chip and field are imitated Should the grid of pipe Q1 be connected, the source electrode of field-effect tube Q1 is connected by capacitor C with the output end of circuit, the drain electrode of field-effect tube Q1 It is connected on the node between inductance L and diode D.

Preferably, the MCU single-chip microcontroller model are as follows: S9KEAZN8A.

With further reference to the illustrative circuitry of attached drawing 4, its working principles are as follows: this circuit is mainly by bypass circuit, boost liter Volt circuit and MCU sampling control circuit are constituted.The bypass circuit is made of switching device SW, SW can be relay or Power MOS pipe constant power switching device；When bypass circuit works normally, SW can be opened and in an ON state, and input voltage is straight Output is led to, boost booster circuit preferably must be held in closed state at the same time.It is other when boost booster circuit works normally Road circuit preferably must be held in closed state, and bypass and the working condition of voltage regulator circuit pass through input voltage sampling, igniting letter by MCU Number etc. carry out output control.The reversed polarity protection circuit of diagram is mainly made of N-MOS pipe Q, resistance R3, and wherein input voltage is adopted Sample circuit is given to MCU input voltage after being divided input voltage by R1 and R2 samples AD mouthfuls, and control circuit continues to use existing list Piece machine input voltage sample circuit and output signal control circuit.Wherein input voltage sample circuit is by R1 and R2 by input voltage The input voltage that MCU is given to after partial pressure samples AD mouthfuls；Output signal controls the VCC power supply of boost driving chip, while for anti- Connect the control of N-MOS pipe Q.

The utility model low cost, high reliability lossless reversed polarity protection circuit design scheme, be to have optimization The optimization of the further cost and performance of scheme, can be effectively reduced quiescent dissipation, save the cost, at the same improve circuit can By property.Certainly, it for the product of every field, needs to design the occasion of reversed polarity protection circuit, this can be used practical new Prioritization scheme provided by type, as long as its circuit structure is similar, principle and function are identical, within the protection scope of the present patent, Details are not described herein.

The description of above preferred embodiment enables those skilled in the art to make or use the utility model.These are implemented The various modifications of example will be apparent to the person skilled in the art, and the General Principle defined here can be applied Without departing from the spirit or scope of the utility model in other embodiments.Therefore, the utility model be not limited to shown here as Embodiment, and to meet and the principle and the consistent broadest range of novel feature that disclose here.

Claims (2)

1. a kind of lossless reversed polarity protection circuit structure, it is characterised in that: it is to be connected on power supply cathode by power N-MOS pipe End carries out reverse polarity protection by the on-off of metal-oxide-semiconductor, and driving control signal is borrowed from the intelligent control of single-chip microprocessor MCU Existing single-chip microcontroller is under-voltage in product circuit, control signals of overvoltage protection control circuits, to control anti-reverse N-MOS pipe；Its Physical circuit connection relationship is as follows: it includes resistance R1, R2 and R3, capacitor C, inductance L, diode D and D1, triode PNP and NPN, field-effect tube Q and Q1, switching device SW, MCU single-chip microcontroller and boost driving chip；The MCU single-chip microcontroller voltage sample Input terminal is connected after passing sequentially through resistance R2, resistance R1 and FUSE with automobile storage battery anode, the enable signal output of MCU single-chip microcontroller End is connected with the base stage of NPN triode, and the emitter of NPN triode is grounded, the collector of NPN triode and PNP triode Base stage is connected, and the emitter of PNP triode is connected with the cathode of diode D1, the just extremely output end of circuit of diode D1； The collector of PNP triode is connected to the VCC foot of boost driving chip and the G foot of N-MOS pipe Q simultaneously；The anode of automobile storage battery Pass sequentially through the output end that circuit is connected to after fuse, inductance L and diode D；Switching device SW composition bypass circuit with The left end inductance L and diode D1 right end are in parallel；The drain D of N-channel field-effect tube Q is connected and connects with the cathode of automobile storage battery , there is a parasitic body diode on ground between the source S and drain electrode of field-effect tube Q, the source S and grid G of field-effect tube Q it Between parallel resistance R3, the grid G of field-effect tube Q is extremely connected with the VCC of boost driving chip；The output end of boost driving chip It is connected with the grid of field-effect tube Q1, the source electrode of field-effect tube Q1 is connected by capacitor C with the output end of circuit, field-effect tube Q1 Drain electrode be connected on the node between inductance L and diode D.

2. lossless reversed polarity protection circuit structure according to claim 1, it is characterised in that: the MCU monolithic type Number are as follows: S9KEAZN8A.