CN217240590U

CN217240590U - Power supply circuit

Info

Publication number: CN217240590U
Application number: CN202122903824.8U
Authority: CN
Inventors: 不公告发明人
Original assignee: Mornsun Guangzhou Science and Technology Ltd
Current assignee: Mornsun Guangzhou Science and Technology Ltd
Priority date: 2021-11-25
Filing date: 2021-11-25
Publication date: 2022-08-19
Anticipated expiration: 2031-11-25

Abstract

The utility model relates to a power supply circuit, include: the circuit comprises a linear voltage stabilizing circuit, a constant current circuit and a hysteresis comparison switch circuit; one end of the linear voltage stabilizing circuit is used for being connected with a high-voltage input power supply, and the other end of the linear voltage stabilizing circuit is respectively connected with the constant current circuit and the hysteresis comparison switch circuit and is used for carrying out first voltage reduction on a high-voltage signal input by the high-voltage input power supply to obtain a first voltage reduction signal; the other end of the constant current circuit is connected with one end of the hysteresis comparison switch circuit and is used for converting the first voltage reduction signal into a low-voltage constant current signal; the other end of the hysteresis comparison switch circuit is used for being connected with a load and controlling the output voltage output to the load according to the low-voltage constant-current signal. The utility model provides a lower and more invariable supply circuit can prevent that the too big device that leads to of impulse circuit from damaging and satisfying and keep the same activation time under the high-low pressure.

Description

Power supply circuit

Technical Field

The utility model relates to a switching power supply field, in particular to power supply circuit.

Background

The switch power supply is started by providing a proper voltage for the control chip, and the control chip can work, so that the switch power supply is started. The starting circuit comprises a chip external power supply and a chip internal power supply, wherein the external power supply comprises various power supply modes such as linear power supply, RC power supply, BUCK, RCC, PSR and the like, and the chip internal power supply generally comprises linear power supply and a constant current power supply circuit carried by the chip to realize starting. In the switching power supply field of high voltage and super wide voltage input, general chips are all from taking constant current power supply circuit, or adopt external RC circuit to start the power supply, or external constant current power supply chip, but these power supply modes can have certain defect:

the chip-mounted constant current power supply circuit is generally small in current, long in starting time and incapable of adjusting time, in addition, the RC circuit is long in starting time when supplying power, and the starting time is large in difference under the condition that the input voltage range is wide.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at overcoming at least one kind defect among the above-mentioned prior art, provide a supply circuit for provide a lower and more invariable supply circuit, can prevent that the too big device that leads to of impulse circuit from damaging and satisfy and keep the same start-up time under the high-low pressure.

The utility model discloses the scheme of taking does:

in one aspect, a power supply circuit is provided, including: the circuit comprises a linear voltage stabilizing circuit, a constant current circuit and a hysteresis comparison switch circuit; one end of the linear voltage stabilizing circuit is used for being connected with a high-voltage input power supply, and the other end of the linear voltage stabilizing circuit is respectively connected with the constant current circuit and the hysteresis comparison switch circuit and is used for carrying out first voltage reduction on a high-voltage signal input by the high-voltage input power supply to obtain a first voltage reduction signal;

the other end of the constant current circuit is connected with one end of the hysteresis comparison switch circuit and is used for converting the first voltage reduction signal into a low-voltage constant current signal;

the other end of the hysteresis comparison switch circuit is used for being connected with a load and controlling the output voltage output to the load according to the low-voltage constant-current signal.

The linear voltage stabilizing circuit is used for carrying out first voltage reduction on a high-voltage signal input by a high-voltage input power supply and providing proper voltage for the constant current circuit, so that the constant current circuit converts the first voltage reduction signal into a low-voltage constant current signal, and the hysteresis comparison switch circuit is used for controlling output voltage according to the low-voltage constant current signal, so that adjustable supply current can be provided for a load, and different output voltages can be output.

Preferably, the hysteresis comparison switch circuit comprises a hysteresis comparison circuit, a switch circuit and a capacitor C1, wherein a first end of the switch circuit is connected with the constant current circuit, a second end of the switch circuit is connected with a first end of the hysteresis comparison circuit, and a third end of the switch circuit is respectively connected with the capacitor C1 and a third end of the hysteresis comparison circuit and is used for being connected with the load; the second end of the hysteresis comparison circuit is also respectively connected with the constant current circuit and the linear voltage stabilizing circuit, and the third end of the hysteresis comparison circuit is also connected with the capacitor C1 and is used for being connected with the load.

The hysteresis comparison circuit supplies power through a linear voltage stabilizing circuit, compares the output voltage sampled and output to a load with a self reference, and when the output voltage is higher than a set upper limit voltage, the second end outputs a low level to control the switch circuit to be switched off, so that the capacitor C1 discharges electricity; when the output voltage is lower than the set lower limit voltage, the second end outputs high level, and the capacitor C1 is controlled to be charged, so that different output voltages are output.

Preferably, the hysteresis comparison circuit comprises a reference voltage unit U1, a resistor R5, a resistor R8, a resistor R9, a resistor R6, a resistor R7, a resistor R10 and a transistor Q4, wherein the cathode of the reference voltage unit U1 is connected with the constant current circuit and the linear voltage stabilizing circuit through the resistor R5 respectively, the base of the transistor Q4 through the resistor R9, the anode is grounded, the reference terminal is connected with the collector of the transistor Q4 through the resistor R10, the emitter of the transistor Q4 through the resistor R6 respectively, one end of the resistor R8, the capacitor C1, the load and the resistor R7; the base of the triode Q4 is further connected to the other end of the resistor R8, and further connected to the second end of the switch circuit and the resistor R5 through the resistor R9, respectively.

Preferably, the hysteresis comparison circuit is provided with an operational amplifier or a comparator; the output end of the operational amplifier or the comparator is connected with the second end of the switch circuit, the first input end of the operational amplifier or the comparator is respectively connected with the constant current circuit and the linear voltage stabilizing circuit, and the second input end of the operational amplifier or the comparator is respectively connected with the capacitor C1 and the third end of the switch circuit and is used for being connected with the load.

Preferably, the switch circuit is an N-type MOS transistor Q3, the drain of the N-type MOS transistor Q3 is used as the first terminal, the gate is used as the second terminal, and the source is used as the third terminal and is respectively connected to the capacitor C1, the third terminal of the hysteresis comparison circuit, and the load.

Preferably, the constant current circuit comprises a resistor R3, a resistor R4, a triode Q2 and a voltage regulator tube Z2; the triode Q2 is a PNP type triode, the emitter of the triode Q2 is respectively connected with the linear voltage stabilizing circuit and the hysteresis comparison switch circuit through the resistor R3, the collector is connected with the hysteresis comparison switch circuit, the base is respectively connected with the linear voltage stabilizing circuit and the hysteresis comparison switch circuit through the voltage stabilizing tube Z2 and is grounded through the current limiting resistor R4,

or the triode Q2 is an NPN type triode, an emitter of the triode Q2 is connected with the hysteretic comparison switch circuit through the resistor R3, a collector of the triode Q2 is connected with the constant current circuit and the hysteretic comparison switch circuit respectively, and a base of the triode Q2 is connected with the constant current circuit and the hysteretic comparison switch circuit respectively through the resistor R4 and connected with the hysteretic comparison switch circuit through the voltage-stabilizing tube Z2.

Preferably, the linear voltage stabilizing circuit comprises a voltage regulator tube Z1, one or more resistors R1, one or more resistors R2 and an MOS tube Q1, wherein the drain electrode of the MOS tube Q1 is used for being connected with the high-voltage input power supply through the resistor R2, the source electrode of the MOS tube Q1 is respectively connected with the constant current circuit and the hysteresis comparison switch circuit, and the grid electrode of the MOS tube Q1 is used for being connected with the high-voltage input power supply through the resistor R1 and is grounded through the voltage regulator tube Z1.

Preferably, when the number of the resistors R1 is plural, the plural resistors R1 are connected in parallel and/or in series.

Preferably, when the number of the resistors R2 is multiple, the resistors R2 are connected in parallel and/or in series.

In another aspect, a power supply circuit is provided, including: the voltage regulator comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a voltage regulator tube Z1, an MOS tube Q1, a triode Q2, a voltage regulator tube Z2, an N-type MOS tube Q3, a triode Q4, a reference voltage unit U1 and a capacitor C1; the drain electrode of the MOS tube Q1 is used for being connected with the high-voltage input power supply through the resistor R2, the source electrode of the MOS tube Q1 is connected with the cathode of the voltage regulator tube Z2 and the emitter electrode of the triode Q2 through the resistor R3, and the source electrode of the MOS tube Q1 is also respectively connected with the grid electrode of the N-type MOS tube Q3, one end of the resistor R9 and the cathode of the reference voltage unit U1 through the resistor R5; the base electrode of the triode Q2 is respectively connected with the anode of the voltage regulator tube Z2 and grounded through the resistor R4, and the collector electrode of the triode Q2 is connected with the drain electrode of the N-type MOS tube Q3; the source electrode of the N-type MOS transistor Q3 is respectively connected with one end of the capacitor C1 and is used for being connected with a load, and the grid electrode of the N-type MOS transistor Q3 is also respectively connected with the base electrode of the triode Q4 and one end of the resistor R8 through the resistor R9; an emitter of the transistor Q4 is connected to one end of the resistor R9 through the resistor R8, to the reference terminal of the reference voltage unit U1 through the resistor R6, and to a load, respectively, and a collector is connected to the reference terminal of the reference voltage unit U1 through the resistor R10; the reference end of the reference voltage unit U1 is also connected with the load through the resistor R6, connected with the ground through the resistor R7 and connected with the anode of the reference voltage unit U1; the anode of the voltage regulator tube Z1 and the other end of the capacitor C1 are both grounded.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model can provide an adjustable supply current under high voltage input, prevent the device from being damaged due to larger impact current, and provide a supply current with more fixed charging time under different input voltages, thereby realizing the same starting time under high and low input voltages; the utility model discloses have the output voltage return difference that can set up, can realize different output starting voltage, different power supply occasions can be tried.

Drawings

FIG. 1 is a block diagram of a power supply circuit according to an embodiment;

FIG. 2 is a circuit diagram of the power supply circuit according to one embodiment;

FIG. 3 is a circuit diagram of the power supply circuit according to the second embodiment;

FIG. 4 is a circuit diagram of the power supply circuit according to the third embodiment;

fig. 5 is a detailed circuit diagram of the power supply circuit according to the third embodiment.

Detailed Description

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

First embodiment

As shown in fig. 1, in the present embodiment, there is provided a power supply circuit including: the circuit comprises a linear voltage stabilizing circuit, a constant current circuit and a hysteresis comparison switch circuit; one end of the linear voltage stabilizing circuit is used for being connected with a high-voltage input power supply, and the other end of the linear voltage stabilizing circuit is respectively connected with the constant current circuit and the hysteresis comparison switch circuit and is used for carrying out first voltage reduction on a high-voltage signal input by the high-voltage input power supply to obtain a first voltage reduction signal;

The linear voltage stabilizing circuit is used for carrying out first voltage reduction on a high-voltage signal input by a high-voltage input power supply to provide proper voltage for the constant current circuit, so that adjustable power supply current can be provided under high-voltage input, and damage to a device due to generation of larger impact current is prevented; the constant current circuit converts the first voltage reduction signal into a low-voltage constant current signal, the hysteresis comparison switch circuit controls the output voltage according to the low-voltage constant current signal, the purpose that a power supply current with relatively fixed charging time can be provided under different input voltages is achieved, the purpose that the same starting time is provided under high and low input voltages is achieved, therefore, an adjustable power supply current can be provided for a load, and different output voltages are output.

In one embodiment, the hysteresis comparison switch circuit comprises a hysteresis comparison circuit, a switch circuit and a capacitor C1, wherein a first end of the switch circuit is connected with the constant current circuit, a second end of the switch circuit is connected with a first end of the hysteresis comparison circuit, and a third end of the switch circuit is respectively connected with the capacitor C1, a third end of the hysteresis comparison circuit and used for being connected with the load; the second end of the hysteresis comparison circuit is also respectively connected with the constant current circuit and the linear voltage stabilizing circuit, and the third end of the hysteresis comparison circuit is also connected with the capacitor C1 and is used for being connected with the load.

As shown in fig. 2, as a specific embodiment of the hysteretic comparison circuit, the hysteretic comparison circuit includes a reference voltage unit U1, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, and a transistor Q4, wherein a cathode of the reference voltage unit U1 is connected to the constant current circuit and the linear voltage stabilizing circuit through the resistor R5, a base of the transistor Q4 through the resistor R9, an anode of the reference voltage unit U9 is grounded, a reference terminal of the reference voltage unit U3626 is connected to a collector of the transistor Q4 through the resistor R10, an emitter of the transistor Q4 through the resistor R6, one terminal of the resistor R8, the capacitor C1, and the reference terminal is connected to the load and is grounded through the resistor R7; the base of the triode Q4 is further connected to the other end of the resistor R8, and further connected to the second end of the switch circuit and the resistor R5 through the resistor R9, respectively.

As a specific embodiment of the switch circuit, the switch circuit is an N-type MOS transistor Q3, a drain of the N-type MOS transistor Q3 is a first terminal, a gate is a second terminal, and a source is a third terminal, which is respectively connected to the capacitor C1, a third terminal of the hysteresis comparator circuit, and the load.

As a specific embodiment of the constant current circuit, the constant current circuit includes a resistor R3, a resistor R4, a triode Q2, and a voltage regulator tube Z2; the triode Q2 is a PNP type triode, the emitter of the triode Q2 is respectively connected with the linear voltage stabilizing circuit and the hysteresis comparison switch circuit through the resistor R3, the collector of the triode Q2 is connected with the hysteresis comparison switch circuit, and the base of the triode Q2 is respectively connected with the linear voltage stabilizing circuit and the hysteresis comparison switch circuit through the voltage stabilizing tube Z2 and is grounded through the resistor R4.

As a specific embodiment of the linear voltage stabilizing circuit, the linear voltage stabilizing circuit includes a voltage regulator tube Z1, one or more resistors R1, one or more resistors R2, and a MOS tube Q1, a drain of the MOS tube Q1 is connected to the high-voltage input power supply through the resistor R2, a source of the MOS tube Q1 is connected to the constant current circuit and the hysteresis comparison switch circuit, respectively, and a gate of the MOS tube Q1 is connected to the high-voltage input power supply through the resistor R1 and grounded through the voltage regulator tube Z1.

Specifically, the cathode of the reference voltage unit U1 is connected to the resistor R3 through the resistor R5, the source of the MOS transistor Q1, the base of the transistor Q4 through the resistor R9, the anode is grounded, the reference terminal is connected to the collector of the transistor Q4 through the resistor R10, the emitter of the transistor Q4 through the resistor R6, one end of the resistor R8, the capacitor C1, the load, and the resistor R7; the base electrode of the triode Q4 is further connected with the other end of the resistor R8, and is further connected with the second end of the N-type MOS transistor Q3 and the resistor R5 through the resistor R9, respectively, the drain electrode of the N-type MOS transistor Q3 is connected with the collector electrode of the triode Q2, and the emitter electrode of the N-type MOS transistor Q3 is connected with the source electrode of the MOS transistor Q1 through the resistor R3.

In a specific embodiment, the reference voltage unit U1 is a TL431 reference chip, and the working principle of this embodiment is as follows: the linear voltage stabilizing circuit with the MOS tube Q1 as the core is used for reducing the voltage of an input high-voltage signal to obtain a first reduced voltage signal, the maximum output voltage of the first reduced voltage signal is determined by a voltage stabilizing tube Z1, a proper voltage is provided for a constant current circuit consisting of a triode Q2 as the core, a resistor R1 is used for limiting the current of the voltage stabilizing tube Z1, wherein the number of the circuits R1 can be 1 or more, the resistances of a plurality of resistors R1 can be the same or different, the connection modes of the resistors R1 can be in series connection or in parallel connection, or in combination of series connection and parallel connection, specifically, different resistances, packages and the number can be selected according to different constant current, and the limitation is avoided; the MOS tube Q1 is a high-voltage-resistant MOS tube and can work under a higher input voltage, the resistor R2 is used for realizing power consumption transfer, the MOS tube Q1 is prevented from being damaged due to overheating caused by bearing higher power consumption, adjustable power supply current can be provided under high-voltage input, damage of devices caused by generation of higher impact current is prevented, the number of the resistors R2 can be 1 or more, the resistances of the resistors R2 can be the same or different, the connection modes of the resistors R2 can be in series connection or in parallel connection, or in combination of series connection and parallel connection, different resistances, packages and the number can be selected according to different constant current, and limitation is not required; the constant current circuit is composed of a triode Q2 as a core and is used for providing proper constant current (also called as a low-voltage constant current signal) for a load, the constant current is jointly determined by a voltage regulator tube Z2 and a resistor R3, wherein the constant current calculation formula of the triode Q2 is shown as a formula (1):

wherein, Vbe is the voltage between the base electrode and the emitter electrode of the triode Q2; the resistor R4 is used for limiting the current of the voltage regulator tube Z2; the hysteresis comparison circuit with the reference voltage unit U1 as the core is used to control the on/off of the N-type MOS transistor Q3, the reference voltage unit U1 samples the output voltage V of the capacitor C1 through the resistor R6 and the resistor R7, since the capacitor C1 has no voltage at first, the voltage at the reference end of the reference voltage unit U1 is very low, and at this time, the reference voltage unit U1 is in an off state, the resistor R5 charges the G pole (gate) of the N-type MOS transistor Q3 through the output voltage at the S pole (source) of the N-type MOS transistor Q1, and since the N-type MOS transistor Q3 is connected to the output end of the constant current source, the N-type MOS transistor Q3 is immediately turned on and charges the capacitor C1 through the constant current, the output voltage V will reach the upper limit voltage value set by the resistors R6 and R7, and the upper limit voltage calculation method is as formula (2):

wherein Vomax represents an upper limit voltage, Vref represents a reference voltage;

when the output voltage V reaches the upper limit voltage value set by the resistor R6 and the resistor R7, the reference voltage unit U1 is turned on and pulls the cathode down, the N-type MOS transistor Q3 is turned off, on the other hand, since the cathode of the reference voltage unit U1 is pulled down, the resistor R8 and the resistor R9 flow current, the transistor Q4 is turned on in saturation, at this time, the resistor R10 and the resistor R6 become a parallel relation, which is equivalent to two resistors sampling the output voltage, and then the lower limit value of the output voltage V is calculated as shown in formula (3):

vomin represents a lower limit voltage, the capacitor C1 supplies power to the load due to the fact that the N-type MOS transistor Q3 is turned off, voltage drop is reduced, when the output voltage V is lower than the lower limit value, the reference voltage unit U1 is turned back to the cut-off state, the N-type MOS transistor Q3 is turned on immediately to charge the capacitor C1 again, when the output voltage V is higher than the upper limit value, charging is stopped, and the steps are repeated, so that a power supply current with fixed charging time can be provided under different input voltages, the same starting time is achieved under the high input voltage and the low input voltage, an adjustable power supply current can be provided for the load, and different output voltages V are output.

Second embodiment

Different from embodiment 1, in the present embodiment, referring to fig. 3, fig. 3 is a schematic circuit diagram of the power supply circuit in the present embodiment, where the constant current circuit includes a resistor R3, a resistor R4, a transistor Q2, and a voltage regulator tube Z2; the triode Q2 is an NPN type triode, an emitting electrode of the triode Q2 is connected with the hysteresis comparison switch circuit through the resistor R3, a collecting electrode of the triode Q2 is respectively connected with the constant current circuit and the hysteresis comparison switch circuit, a base electrode of the triode Q2 is respectively connected with the constant current circuit and the hysteresis comparison switch circuit through the resistor R4, and the base electrode of the triode Q2 is connected with the hysteresis comparison switch circuit through the voltage stabilizing tube Z2.

Third embodiment

Unlike embodiment 1, in the present embodiment, please refer to fig. 4, fig. 4 is a circuit schematic diagram of the power supply circuit of the present embodiment, and the hysteresis comparison circuit is provided with an operational amplifier or a comparator; the output end of the operational amplifier or the comparator is connected with the second end of the switch circuit, the first input end of the operational amplifier or the comparator is respectively connected with the constant current circuit and the linear voltage stabilizing circuit, and the second input end of the operational amplifier or the comparator is respectively connected with the capacitor C1 and the third end of the switch circuit and is used for being connected with the load.

Specifically, a hysteresis comparison circuit composed of an operational amplifier or a comparator as a core has a first input terminal of VCC terminal, which is connected to the source of the MOS transistor Q1, one terminal of the resistor R3, and the cathode of the regulator Z2, a second input terminal of FB terminal, which is connected to the source of the N-type MOS transistor Q3 and the capacitor C1, and an output terminal of OUT terminal, which is connected to the gate of the N-type MOS transistor Q3; the VCC end supplies power through a linear voltage stabilizing circuit, the FB end is used for sampling output voltage and comparing the output voltage with the reference of a hysteresis comparison circuit, when the output voltage is higher than a set voltage, the OUT end outputs low level, an N-type MOS tube Q3 is closed, and a capacitor C1 discharges; when the output voltage V is lower than the set lower limit voltage, the OUT terminal outputs a high level, and the N-type MOS transistor Q3 is turned on to charge the capacitor C1.

Specifically, as shown in fig. 5, which is a specific circuit diagram of the power supply circuit of this embodiment, a hysteresis comparison circuit composed of an operational amplifier as a core is taken as an example, and the hysteresis comparison circuit includes an operational amplifier U2, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, and a capacitor C2; an output end 2 of the operational amplifier is connected with a gate of the N-type MOS transistor Q3 and is connected with a first input end 1 through a resistor R11, the first input end 1 is further connected with a source of the MOS transistor Q1, a cathode of the resistor R3 and a cathode of the voltage regulator Z2 through a resistor R13 respectively and is grounded through a resistor R14, a second input end 3 is connected with a source of the capacitor C1 and a source of the N-type MOS transistor Q3 through a resistor R12 respectively and is used for being connected with the load and is grounded through a resistor R14, a negative power end 2 is grounded, and a positive power end 5 is grounded through a capacitor C2.

The voltage reduced by the linear voltage-stabilizing circuit provides a proper working voltage for the operational amplifier U2, the working voltage is divided by the resistor R13 and the resistor R14 and then provided to the positive phase input end (the first input end 1) of the operational amplifier U2, the output voltage V is divided by the resistor R12 and the resistor R15 and then provided to the reverse phase input end (the second input end 3) of the operational amplifier U2, because the voltage at the positive phase input end is not established at the beginning of the output voltage V, the voltage at the positive phase input end is higher than that at the reverse phase input end, the output end 4 of the operational amplifier U2 outputs high level to drive the N-type MOS tube Q3, the voltage at the positive phase input end is further increased after the N-type MOS tube Q3 is conducted, because the operational amplifier U2 outputs high level, the current is provided to the positive phase input end of the operational amplifier U2 through the resistor R11, and when the output voltage V reaches the set value, the output voltage V is divided by the resistor R12 and the resistor R15 and then is supplied to the voltage of the inverting input end of the operational amplifier U2 to be higher than the voltage of the non-inverting input end, and the output end 4 of the operational amplifier U2 is rapidly changed into low level, so that the power supply of the output voltage V is stopped, and the charging voltage is prevented from being too high; on the other hand, after the output terminal 4 of the operational amplifier U2 becomes low level, one terminal of the positive power terminal 5 is pulled low, the positive power supply terminal 5 shunts the current at the positive input terminal, pulls the voltage at the positive input terminal slightly low, thereby ensuring that the voltage of the inverting input end is higher than that of the non-inverting input end, keeping the output of the output end 4 at a low level, when the output voltage V drops to a certain value, the voltage is divided by the resistor R12 and the resistor R15 and then provided to the inverting input terminal of the operational amplifier U2, which is lower than the non-inverting input terminal, the output terminal 4 of the operational amplifier U2 outputs a high level, the N-type MOS transistor Q3 is driven again, the above steps are repeated to realize that a power supply current with fixed charging time can be provided under different input voltages V, the same starting time can be realized under high and low input voltages, therefore, an adjustable supply current can be provided for the load, and different output voltages V can be output.

Fourth embodiment

In the present embodiment, there is provided a power supply circuit including: the circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a voltage regulator tube Z1, an MOS tube Q1, a triode Q2, a voltage regulator tube Z2, an N-type MOS tube Q3, a triode Q4, a reference voltage unit U1 and a capacitor C1; the drain electrode of the MOS tube Q1 is used for being connected with the high-voltage input power supply through the resistor R2, the source electrode of the MOS tube Q1 is connected with the cathode of the voltage regulator tube Z2 and the emitter electrode of the triode Q2 through the resistor R3, and the source electrode of the MOS tube Q1 is also respectively connected with the grid electrode of the N-type MOS tube Q3, one end of the resistor R9 and the cathode of the reference voltage unit U1 through the resistor R5; the base electrode of the triode Q2 is respectively connected with the anode of the voltage-stabilizing tube Z2 and grounded through the resistor R4, and the collector electrode is connected with the drain electrode of the N-type MOS tube Q3; the source electrode of the N-type MOS transistor Q3 is respectively connected with one end of the capacitor C1 and is used for being connected with a load, and the grid electrode of the N-type MOS transistor Q3 is also respectively connected with the base electrode of the triode Q4 and one end of the resistor R8 through the resistor R9; an emitter of the transistor Q4 is connected to one end of the resistor R9 through the resistor R8, to the reference terminal of the reference voltage unit U1 through the resistor R6, and to a load, respectively, and a collector is connected to the reference terminal of the reference voltage unit U1 through the resistor R10; the reference end of the reference voltage unit U1 is also connected with the load through the resistor R6, connected with the ground through the resistor R7 and connected with the anode of the reference voltage unit U1; the anode of the voltage regulator tube Z1 and the other end of the capacitor C1 are both grounded.

Specifically, the MOS tube Q1, the resistor R1, the resistor R2 and the voltage regulator tube Z1 form a linear voltage stabilizing circuit which is used for reducing the voltage of an input high-voltage signal, the maximum output voltage of the linear voltage stabilizing circuit is determined by the voltage regulator tube Z1, the resistor R1 is used for limiting the current of the voltage regulator tube Z1, the resistor R2 is used for realizing power consumption transfer, the MOS tube Q1 is prevented from bearing larger power consumption to cause overheating damage, adjustable power supply current can be provided under high-voltage input, and the device damage caused by larger impact current is prevented; the resistor R3, the resistor R4, the triode Q2 and the voltage regulator tube Z2 form a constant current circuit which is used for providing proper constant current for a load, the constant current is jointly determined by the voltage regulator tube Z2 and the resistor R3, and the resistor R4 is used for limiting the current of the voltage regulator tube Z2; the resistor R5, the resistor R6, the resistor R7, the resistor R8, the resistor R9, the resistor R10, the N-type MOS tube Q3, the triode Q4, the reference voltage unit U1 and the capacitor C1 form a hysteresis comparison switch circuit, the hysteresis comparison switch circuit is used for controlling the size of output voltage output to a load according to constant current provided by a constant current circuit, the reference voltage unit U1 samples the output voltage V of the capacitor C1 through the resistor R6 and the resistor R7, as the capacitor C1 has no voltage at first, the voltage of the reference end of the reference voltage unit U1 is very low, the reference voltage unit U1 is in an off state, the resistor R5 charges the G pole of the N-type MOS tube Q3 through the output voltage of the S pole of the Q1 end of the N-type MOS tube, and as the N-type MOS tube Q3 is connected with the output end of a constant current source, then the N-type MOS tube Q3 is connected and charges the capacitor C1 through a constant current source, and the output voltage V reaches the upper limit value set according to the resistor R6 and the resistor R7, when the output voltage V reaches the upper limit voltage value set by the resistor R6 and the resistor R7, the reference voltage unit U1 is turned on and the cathode is pulled down, the N-type MOS tube Q3 is turned off, on the other hand, as the cathode of the reference voltage unit U1 is pulled down, the resistor R8 and the resistor R9 have current flowing, the triode Q4 is turned on in saturation, at this time, the resistor R10 and the resistor R6 become a parallel relation, which is equivalent to two resistors sampling the output voltage, as the N-type MOS tube Q3 is turned off, the capacitor C1 supplies power to the load, the voltage drop is reduced, when the output voltage V is lower than the lower limit value, the reference voltage unit U1 is turned back to the cut-off state, the N-type MOS tube Q3 is turned on immediately, the capacitor C1 is charged again, when the output voltage V is higher than the upper limit value, the charging is stopped, and the operation is repeated, so that a more fixed power supply current can be provided under different input voltages, the same starting time is realized under high and low input voltages, so that an adjustable supply current can be provided for a load, and different output voltages V are output.

Obviously, the above embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not limitations to the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A power supply circuit, comprising: the circuit comprises a linear voltage stabilizing circuit, a constant current circuit and a hysteresis comparison switch circuit; one end of the linear voltage stabilizing circuit is used for being connected with a high-voltage input power supply, and the other end of the linear voltage stabilizing circuit is respectively connected with the constant current circuit and the hysteresis comparison switch circuit and is used for carrying out first voltage reduction on a high-voltage signal input by the high-voltage input power supply to obtain a first voltage reduction signal;

2. The power supply circuit according to claim 1, wherein the hysteretic comparison switch circuit comprises a hysteretic comparison circuit, a switch circuit and a capacitor C1, a first terminal of the switch circuit is connected with the constant current circuit, a second terminal of the switch circuit is connected with a first terminal of the hysteretic comparison circuit, and a third terminal of the switch circuit is respectively connected with the capacitor C1, a third terminal of the hysteretic comparison circuit and is used for being connected with the load; the second end of the hysteresis comparison circuit is also respectively connected with the constant current circuit and the linear voltage stabilizing circuit, and the third end of the hysteresis comparison circuit is also connected with the capacitor C1 and is used for being connected with the load.

3. The power supply circuit as claimed in claim 2, wherein the hysteretic comparison circuit comprises a reference voltage unit U1, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10 and a transistor Q4, the cathode of the reference voltage unit U1 is connected to the constant current circuit and the linear voltage stabilizing circuit through the resistor R5, the base of the transistor Q4 through the resistor R9, the anode is grounded, the reference terminal is connected to the collector of the transistor Q4 through the resistor R10, the emitter of the transistor Q4 through the resistor R6, one terminal of the resistor R8, the capacitor C1, the reference terminal is connected to the load and is grounded through the resistor R7; the base of the triode Q4 is further connected to the other end of the resistor R8, and further connected to the second end of the switch circuit and the resistor R5 through the resistor R9, respectively.

4. The power supply circuit according to claim 2, wherein the hysteresis comparison circuit is provided with an operational amplifier or a comparator; the output end of the operational amplifier or the comparator is connected with the second end of the switch circuit, the first input end of the operational amplifier or the comparator is respectively connected with the constant current circuit and the linear voltage stabilizing circuit, and the second input end of the operational amplifier or the comparator is respectively connected with the capacitor C1 and the third end of the switch circuit and is used for being connected with the load.

5. A power supply circuit as claimed in any one of claims 2 to 4, wherein the switching circuit is an N-type MOS transistor Q3, the drain of the N-type MOS transistor Q3 is used as the first terminal, the gate is used as the second terminal, and the source is used as the third terminal and is connected to the capacitor C1, the third terminal of the hysteretic comparator circuit and the load respectively.

6. The power supply circuit as claimed in claim 1, wherein the constant current circuit comprises a resistor R3, a resistor R4, a triode Q2 and a voltage regulator tube Z2; the triode Q2 is a PNP type triode, the emitter of the triode Q2 is respectively connected with the linear voltage stabilizing circuit and the hysteresis comparison switch circuit through the resistor R3, the collector is connected with the hysteresis comparison switch circuit, the base is respectively connected with the linear voltage stabilizing circuit and the hysteresis comparison switch circuit through the voltage stabilizing tube Z2 and is grounded through the resistor R4,

or, the triode Q2 is an NPN type triode, the emitter of the triode Q2 is connected with the hysteresis comparison switch circuit through the resistor R3, the collector is connected with the constant current circuit and the hysteresis comparison switch circuit respectively, and the base is connected with the constant current circuit and the hysteresis comparison switch circuit through the resistor R4 and the hysteresis comparison switch circuit through the voltage-regulator tube Z2 respectively.

7. The power supply circuit as claimed in claim 1, wherein the linear voltage regulator circuit comprises a voltage regulator tube Z1, one or more resistors R1, one or more upper resistors R2, and a MOS tube Q1, a drain of the MOS tube Q1 is connected to the high voltage input power supply through the resistor R2, a source of the MOS tube Q1 is connected to the constant current circuit and the hysteretic comparison switch circuit, respectively, and a gate of the MOS tube Q1 is connected to the high voltage input power supply through the resistor R1 and grounded through the voltage regulator tube Z1.

8. The power supply circuit according to claim 7, wherein when the number of the resistors R1 is plural, plural resistors R1 are connected in parallel and/or in series.

9. The power supply circuit according to claim 7, wherein when the number of the resistors R2 is plural, plural resistors R2 are connected in parallel and/or in series.

10. A power supply circuit, comprising: the circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a voltage regulator tube Z1, an MOS tube Q1, a triode Q2, a voltage regulator tube Z2, an N-type MOS tube Q3, a triode Q4, a reference voltage unit U1 and a capacitor C1; the drain electrode of the MOS tube Q1 is used for being connected with a high-voltage input power supply through the resistor R2, the source electrode of the MOS tube Q1 is connected with the cathode of the voltage regulator tube Z2 and the emitter electrode of the triode Q2 through the resistor R3, and the source electrode of the MOS tube Q1 is also respectively connected with the grid electrode of the N-type MOS tube Q3, one end of the resistor R9 and the cathode of the reference voltage unit U1 through the resistor R5; the base electrode of the triode Q2 is respectively connected with the anode of the voltage regulator tube Z2 and grounded through the resistor R4, and the collector electrode of the triode Q2 is connected with the drain electrode of the N-type MOS tube Q3; the source electrode of the N-type MOS transistor Q3 is respectively connected with one end of the capacitor C1 and is used for being connected with a load, and the grid electrode of the N-type MOS transistor Q3 is also respectively connected with the base electrode of the triode Q4 and one end of the resistor R8 through the resistor R9; an emitter of the transistor Q4 is connected to one end of the resistor R9 through the resistor R8, to the reference terminal of the reference voltage unit U1 through the resistor R6, and to a load, respectively, and a collector is connected to the reference terminal of the reference voltage unit U1 through the resistor R10; the reference end of the reference voltage unit U1 is also connected with the load through the resistor R6, connected with the ground through the resistor R7 and connected with the anode of the reference voltage unit U1; the anode of the voltage regulator tube Z1 and the other end of the capacitor C1 are both grounded.