CN207782395U - A kind of thermal-shutdown circuit and electronic equipment - Google Patents
A kind of thermal-shutdown circuit and electronic equipment Download PDFInfo
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- CN207782395U CN207782395U CN201820164516.3U CN201820164516U CN207782395U CN 207782395 U CN207782395 U CN 207782395U CN 201820164516 U CN201820164516 U CN 201820164516U CN 207782395 U CN207782395 U CN 207782395U
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Abstract
The utility model is related to technical field of integrated circuits, disclose a kind of thermal-shutdown circuit, including：Temperature control circuit and switching power circuit are crossed, the temperature control circuit of crossing connects the switching power circuit；It is described cross temperature control circuit include：First resistor, second resistance, metal-oxide-semiconductor；The first resistor is the thermistor of negative temperature coefficient；The grid of the metal-oxide-semiconductor is connected to the junction of the first resistor and the second resistance, and the source electrode of the metal-oxide-semiconductor connects the other end of the second resistance.By the above-mentioned means, the utility model can solve the temperature for the heating power device that the prior art can not be in pilot switch power supply, and the technical issues of temperature protection point can not be adjusted according to specific product.
Description
Technical field
The utility model embodiment is related to technical field of integrated circuits, more particularly to a kind of thermal-shutdown circuit and electricity
Sub- equipment.
Background technology
With the fast development of electronic equipment, direct-current switch power supply is more and more widely used, Switching Power Supply skill
Art also develops constantly, still, since control circuit is more complicated in Switching Power Supply, transistor and integrated device tolerance electricity punching
It hits poor with the ability of thermal shock, brings inconvenience to user in use.And with the continuous upgrading of product, people couple
The requirement of product is also being continuously improved, and the larger product of bearing power emerges one after another, therefore, in order to protect Switching Power Supply itself and
The safety of load and the safety of product, it is essential to carry out overheat protector to direct-current switch power supply.
Overheat protector carrys out pilot switch electricity often through temperature-sensitive device is arranged inside switching power source chip in the prior art
The temperature of source chip ontology, and actually main heating device is other power components, also, inside switching power source chip
Temperature-sensitive device is set, can there are problems that specific temperature protection point cannot being arranged according to specific product.
Inventor in the process of implementing the utility model, it is found that the relevant technologies have at least the following problems：When load work(
When rate is larger, the temperature of Switching Power Supply and other power devices is excessively high, is easily damaged device, and can not be adjusted according to specific product
Temperature protection point.
Utility model content
The utility model embodiment provides a kind of thermal-shutdown circuit, and solving the prior art can not be in pilot switch power supply
The temperature of heating power device, and can not according to specific product adjust temperature protection point the technical issues of.
In order to solve the above-mentioned technical problem, the utility model embodiment provides following technical scheme：
In a first aspect, the utility model embodiment provides a kind of thermal-shutdown circuit, including：Cross temperature control circuit and switch
Power circuit, the temperature control circuit of crossing connect the switching power circuit；
It is described cross temperature control circuit include：First resistor, second resistance, metal-oxide-semiconductor；
The first resistor is the thermistor of negative temperature coefficient, one end connection second electricity of the first resistor
Resistance, the other end connect the switching power circuit；
The grid of the metal-oxide-semiconductor is connected to the junction of the first resistor and the second resistance, the source of the metal-oxide-semiconductor
Pole connects the other end of the second resistance.
In some embodiments, above-mentioned temperature control circuit of crossing further includes：
First capacitance, first capacitance second resistance in parallel；
3rd resistor, the 3rd resistor connect the drain electrode of the metal-oxide-semiconductor.
In some embodiments, the thermal-shutdown circuit further includes：
Electromagnetic interface filter；
Input rectifying filter circuit；
Switching circuit connects the input rectifying filter circuit；
Transformer, including primary side, primary side and auxiliary winding；
Clamp circuit connects the input rectifying filter circuit and the transformer；
Output rectifier and filter connects the primary side of the transformer；
In some embodiments, above-mentioned input rectifying filter circuit includes：Rectifier bridge, the second capacitance, third capacitance and one
Inductance；Wherein, the zero line of one end of the electromagnetic interface filter and AC power connects, the other end connection of the electromagnetic interface filter
The first input end of the rectifier bridge, the zero line side of the second input terminal connection AC power of the rectifier bridge, the rectifier bridge
The first output end connect with one end of the inductance, and connect with one end of first capacitance, the other end of the inductance
It is connect with one end of second capacitance, the second output terminal of the rectifier bridge, the other end of first capacitance, described second
The other end of capacitance is grounded.
In some embodiments, said clamping circuit includes：Second diode, the 7th resistance, the 6th capacitance, the 8th electricity
Resistance, the 9th resistance；Wherein, the anode of second diode connects the Same Name of Ends of the primary side, second diode
Cathode connects one end of the 7th resistance, and one end of the 6th capacitance connects the other end of the 7th resistance, and described
The other ends of six capacitances connects the inductance, the 6th capacitance described in the 8th resistor coupled in parallel, described in the 9th resistor coupled in parallel
8th resistance.
In some embodiments, said switching circuit includes：4th resistance, the 5th resistance, the 6th resistance, the tenth resistance,
Eleventh resistor, the 4th capacitance, the 5th capacitance, the first triode, the second triode；Wherein, the base stage of second triode
Connect successively with one end of the inductance through the 6th resistance, the 5th resistance, the collector of second triode with it is described
The Same Name of Ends of primary side connects, and the emitter of second triode is grounded through the eleventh resistor；
One end of 4th capacitance connects the different name end of the auxiliary winding, the Same Name of Ends ground connection of the auxiliary winding；
The collector of first triode is connect with the base stage of second triode, the emitter ground connection of first triode,
The base stage of first triode is connect through the tenth resistance with the emitter of second triode.
In some embodiments, above-mentioned output rectifier and filter includes：First diode, the tenth capacitance, the 11st electricity
Hold, the 14th resistance, wherein the tenth capacitance is in parallel with the 11st capacitance, the anode of first diode and secondary
The Same Name of Ends connection of grade side, cathode are connected through the different name end of the tenth capacitance and primary side；14th resistance and described the
Ten capacitances are in parallel, and the 14th resistance is in parallel with the 11st capacitance.
In some embodiments, above-mentioned thermal-shutdown circuit further includes：Feedback circuit, wherein the feedback circuit includes：
Photo-coupler, zener diode, wherein the photo-coupler includes：Light emitting diode and phototriode；
The anode of the zener diode connects the tenth capacitance, and cathode connects the cathode of the light emitting diode, institute
The anode for stating light emitting diode connects the cathode of the first diode；The emitter of the phototriode is grounded, and described photosensitive three
The collector of pole pipe connects the collector of the first triode.
In some embodiments, above-mentioned switching power circuit further includes：Output protection circuit, the output protection circuit packet
It includes：One end of 8th capacitance, the 8th capacitance is connect with the cathode of the tenth capacitance, another termination of the 8th capacitance
Ground.
Second aspect, the utility model embodiment provide a kind of electronic equipment, including above-mentioned thermal-shutdown circuit.
The advantageous effect of the utility model embodiment is：The case where being different from the prior art, the utility model embodiment party
Formula discloses a kind of thermal-shutdown circuit, including：Temperature control circuit and switching power circuit are crossed, it is described to cross temperature control circuit connection
The switching power circuit；It is described cross temperature control circuit include：First resistor, second resistance, metal-oxide-semiconductor；The first resistor is
The thermistor of negative temperature coefficient, the grid of the metal-oxide-semiconductor are connected to the junction of the first resistor and the second resistance,
The source electrode of the metal-oxide-semiconductor connects the other end of the second resistance.By the above-mentioned means, the utility model can solve existing skill
Art can not be in pilot switch power supply heating power device temperature, and temperature protection point can not be adjusted according to specific product
Technical problem.
Description of the drawings
One or more embodiments are illustrated by corresponding attached drawing, these exemplary illustrations not structure
The restriction of pairs of embodiment, the element with same reference numbers label is expressed as similar element in attached drawing, unless there are special
It declares, composition does not limit the figure in attached drawing.
Fig. 1 is a kind of circuit diagram for crossing temperature control circuit that the utility model embodiment provides；
Fig. 2 is a kind of functional block diagram for thermal-shutdown circuit that the utility model embodiment provides；
Fig. 3 is a kind of circuit diagram for thermal-shutdown circuit that the utility model embodiment provides.
Referring to Fig. 1 to Fig. 3,100 be AC power；200 be thermal-shutdown circuit；20 be switching power circuit；210 be defeated
Enter current rectifying and wave filtering circuit；220 be clamp circuit；230 be transformer；240 be absorbing circuit；250 be output rectifier and filter；
260 be output protection circuit；270 be temperature control circuit；280 be switching circuit；290 be feedback circuit；300 be load.
Specific implementation mode
For the ease of understanding the utility model, with reference to the accompanying drawings and detailed description, the utility model is carried out more
Detailed description.It should be noted that when element is expressed " being fixed on " another element, it can be directly in another element
Upper or placed in the middle there may be one or more therebetween elements.When an element is expressed " connection " another element, it can
To be directly to another element or may exist one or more elements placed in the middle therebetween.This specification is used
Term " vertical ", " horizontal ", "left", "right" and similar statement for illustrative purposes only.
Unless otherwise defined, technical and scientific term all used in this specification and the skill for belonging to the utility model
The normally understood meaning of technical staff in art field is identical.Art used in the description of the utility model in this specification
Language is intended merely to the purpose of description specific embodiment, is not intended to limitation the utility model.Art used in this specification
Language "and/or" includes any and all combinations of one or more relevant Listed Items.
Embodiment 1
It is a kind of circuit for crossing temperature control circuit that the utility model embodiment provides also referring to Fig. 1 to Fig. 3, Fig. 1
Schematic diagram, Fig. 2 are a kind of functional block diagrams for thermal-shutdown circuit that the utility model embodiment provides；Fig. 3 is the utility model
A kind of circuit diagram for thermal-shutdown circuit that embodiment provides.
In the present embodiment, cross 270 connecting valve power circuit 20 of temperature control circuit, it is described cross temperature control circuit 270 can be with
According to the temperature of the power device around switching power circuit 20, control switching power circuit 20 is switched on or off.
Wherein, crossing temperature control circuit 270 includes：First resistor R1, second resistance R2, metal-oxide-semiconductor Q1；
The first resistor R1 is the thermistor of negative temperature coefficient, one end connection described second of the first resistor R1
Resistance R2, the other end connect the switching circuit 280, and the first resistor R1 is for monitoring the switching circuit 280 and its week
The temperature of the power device enclosed；
The grid of the metal-oxide-semiconductor Q1 is connected to the junction of the first resistor R1 and the second resistance R2, the MOS
The source electrode of pipe Q1 connects the other end of the second resistance R2, and the metal-oxide-semiconductor Q1 is for controlling the switching power circuit 20.Institute
The source electrode for stating metal-oxide-semiconductor Q1 is also connected with the emitter of the second triode Q3.
Wherein, the first resistor R1 can select different temperature protection points according to different products, such as：Entire electricity
The temperature protection point of road plate needs within 90 degrees Celsius, so that it may to select temperature protection o'clock for 90 degrees Celsius of first resistor
R1, after the temperature on the peripheries first resistor R1 increases, when temperature reaches 90 degrees Celsius, the resistance value of first resistor R1 just becomes connecing
Nearly 0 resistance value or low resistance, the resistance of first resistor R1 become smaller, and electric current is caused to increase, to make the voltage of second resistance R2 increase,
Metal-oxide-semiconductor Q1 meetings unicom is directly forced by metal-oxide-semiconductor Q1 the first triode Q2 shutdowns, to turn off electricity when reaching certain threshold values
Source, and then protect entire switching power circuit 20 and related power device and load 300.After temperature lowers, first
The resistance of resistance R1 increases, and reverts to high impedance status, to which the conducting of metal-oxide-semiconductor Q1 is not achieved in the voltage at the both ends second resistance R2
Voltage, metal-oxide-semiconductor Q1 are disconnected, and the first triode Q2 can be with normal operation.
Specifically, the temperature control circuit 270 of crossing further includes：First capacitance C1 and 3rd resistor R3, first capacitance
The C1 second resistance R2 in parallel, for preventing external interference；The 3rd resistor R3 connects the drain electrode of the metal-oxide-semiconductor Q1, uses
In burning voltage.
In the utility model embodiment, temperature control circuit is crossed by the way that offer is a kind of, the temperature control circuit of crossing includes：The
One resistance, second resistance and metal-oxide-semiconductor；Wherein, the first resistor is the thermistor of negative temperature coefficient, and described first
Different temperature protection points can be arranged in resistance according to different products.By the above-mentioned means, the utility model embodiment can
According to the temperature of the power device around switching power circuit, being switched on or off for switching power circuit is controlled.
Embodiment 2
Referring to Fig. 2, a kind of functional block diagram for thermal-shutdown circuit 200 that the utility model embodiment provides.
In the present embodiment, thermal-shutdown circuit 200 is connected between AC power 100 and load 300, and the excess temperature is protected
Protection circuit 200 includes：Input rectifying filter circuit 210, clamp circuit 220, transformer 230, absorbing circuit 240, output rectification
Filter circuit 250, crosses temperature control circuit 270, switching circuit 280, feedback circuit 290, the transformation at output protection circuit 260
Device 230 includes：Primary side, primary side and auxiliary winding；
Wherein, input rectifying filter circuit 210 is connect with temperature control circuit 270 is crossed, and crosses temperature control circuit 270 and switch electricity
Road 280 connects, and input rectifying filter circuit 270 is connect with clamp circuit 220, and clamp circuit 220 connects with transformer 230
It connects, alternating current becomes direct current after the rectifying and wave-filtering of input rectifying filter circuit 250, the DC powered switching circuit 280
Work, direct current pass through the primary side of transformer 230, and induced voltage is generated in the primary side of transformer 230, transformer 230
Rectifying and wave-filtering rear-guard dynamic load 300 of the induced voltage generated in primary side through output rectifier and filter 250.
After the alternating current of input is carried out rectifying and wave-filtering by the present embodiment by input rectifying filter circuit 220, direct current is exported
Electricity to switching circuit 280 and transformer 250, driving switch circuit 280 works so that the primary side of transformer 250 has electric current warp
It crosses, and generates induced voltage in the primary side and auxiliary winding of transformer 250, the generation induced voltage warp generated in primary side
LED load 300 is driven after the rectifying and wave-filtering of output rectifier and filter 260.The temperature control circuit 270 of crossing passes through monitoring switch
Temperature around circuit 280 and other power devices plays overheat protector to control being switched on or off for switching circuit 280
Effect.
Referring again to 3, a kind of circuit diagram for thermal-shutdown circuit that the utility model embodiment provides.
Based on above-described embodiment, thermal-shutdown circuit 200 further includes：Electromagnetic interface filter RF1, the electromagnetic interface filter RF1's
One end connects the zero line of AC power 100, and the electromagnetic interface filter RF1 is for inhibiting the High-frequency Interference in AC network to electricity
Influence of the low frequency noise to circuit is eliminated in the influence on road.
In above-described embodiment, input rectifying filter circuit 210 includes：Rectifier bridge DB1, inductance L1, the second capacitance C2 and
Third capacitance C3.The rectifier bridge DB1 includes：First input end, the second input terminal, the first output end and second output terminal.
Wherein, the other end of above-mentioned electromagnetic interface filter RF1 connects the first input end of the rectifier bridge DB1, the rectifier bridge
The zero line side of the second input terminal connection AC power 100 of DB1, the first output end of the rectifier bridge DB1 and the inductance L1
One end connection, and connect with one end of the second capacitance C2, the other end of the inductance L1 and the third capacitance C3's
One end connect, the second output terminal of the rectifier bridge DB1, the other end of the second capacitance C2, the third capacitance C3 it is another
One end is grounded.
In the present embodiment, input rectifying filter circuit 210 includes rectification and filtering two parts, and rectifier bridge DB1 constitutes rectification
Part becomes direct current after the rectification processing of the rectified bridge DB1 of alternating current inputted from AC power by alternating current；Filtering part
The filter being made of the second capacitance C2, third capacitance C3, inductance L1, filter is divided to be filtered direct current, it will
Direct current electricity output is to switching power circuit 20 and crosses temperature control circuit 270.
In above-described embodiment, the clamp circuit 220 includes:Second diode D2, the 7th resistance R7, the 6th capacitance C6,
8th resistance R8, the 9th resistance R9；Wherein, the Same Name of Ends of the anode connection primary side of the second diode D2, described second
The cathode of diode D2 connects one end of the 7th resistance R7, and one end of the 6th capacitance C6 connects the 7th resistance R7
The other end, the other end of the 6th capacitance C6 connects the inductance L1, the 8th resistance R8 the 6th capacitances in parallel
C6, the 9th resistance R9 the 8th resistance R8 in parallel.The clamp circuit 220 is for protecting opening in switching circuit 280
Guan Guan makes it not damaged by the impact of peak voltage.
In above-described embodiment, the transformer 230 includes primary side, primary side and auxiliary winding.Wherein, auxiliary winding rises
To the effect for providing pulse width modulating signal.
In above-described embodiment, the absorbing circuit 240 includes：9th capacitance R9, the first diode D1 and thirteenth resistor
R13, wherein the Same Name of Ends of one end connection primary side of the 9th capacitance R9, the other end connect the thirteenth resistor R13,
The first diode D1 in parallel, the absorbing circuit 240 are sharp jointly after the 9th capacitance R9 and thirteenth resistor R13 series connection
Inhibit current-rising-rate with the characteristic that inductive current cannot be mutated, inhibits voltage to rise using the characteristic that capacitance voltage cannot be mutated
Rate improves for filtering out peak voltage and loads unreasonable drawback.
In above-described embodiment, the output rectifier and filter 250 includes：First diode D1, the tenth capacitance C10,
11 capacitance C11, wherein the tenth capacitance C10 is in parallel with the 11st capacitance C11, the sun of the first diode D1
The Same Name of Ends of pole and primary side connects, and cathode is connected through the different name end of the tenth capacitance C10 and primary side.
Specifically, the output rectifier and filter 250 further includes：14th resistance R14, the 14th resistance R14
It is in parallel with the tenth capacitance C10, and the 14th resistance R14 is in parallel with the 11st capacitance C11.14th electricity
Resistance R14 plays the role of current-limiting protection.
In the present embodiment, after the first triode Q2 cut-offs, 230 flyback of transformer, produced by transformer 230 is from primary side
Induced voltage it is reversed, the first diode D1 conducting in output rectifier and filter 250, to the induced electricity exported from primary side
Pressure carries out rectification, and the filter being made of the tenth capacitance C10 and the 14th resistance R14 is filtered place to the induced voltage
Reason removes noise wave removing, output constant current voltage, by the constant current voltage output to load 300.
Meanwhile the induced voltage generated in the auxiliary winding of transformer 230 is reversed, becomes negative voltage, to the 4th capacitance C4
Negative voltage clamper is carried out, the current potential of the 4th capacitance C4 is dragged down；After the energy of transformer 230 is consumed, transformer 230
Auxiliary winding on induced voltage be zero, the voltage at the 4th both ends capacitance C4 restores, and continues driving the first triode Q2 conductings；
When the first triode Q2 conductings, the auxiliary winding of transformer 230 generates positive induced voltage, is filled to the 4th capacitance C4
Electricity, repeats above-mentioned operation principle, and the induced voltage generated in 230 auxiliary winding of transformer constantly carries out the 4th capacitance C4
Charging so that maintain have voltage on the 4th capacitance C4 always, as long as the voltage at the 4th both ends capacitance C4 is more than 0.7V, you can driving
First triode Q2 conductings, continue to execute the above-mentioned course of work.
In above-described embodiment, the output protection circuit 260 includes：8th capacitance C8, one end of the 8th capacitance C8
It is connect with the cathode of the tenth capacitance C10, the other end ground connection of the 8th capacitance C8.The 8th capacitance C8 is safety electricity
Hold, the DM EMI of output voltage, the present embodiment can be inhibited to increase by the 8th capacitance C8 on output loop, avoid the 8th capacitance
There is puncture short phenomenon after C8 failures, it is ensured that safe to use.
In above-described embodiment, the temperature control circuit 270 of crossing includes：First resistor R1, second resistance R2, metal-oxide-semiconductor Q1；
The first resistor R1 is the thermistor of negative temperature coefficient, one end connection described second of the first resistor R1
Resistance R2, the other end connect the switching circuit 280, and the first resistor is for monitoring the switching circuit 280 and its surrounding
Power device temperature；
The grid of the metal-oxide-semiconductor Q1 is connected to the junction of the first resistor R1 and the second resistance R2, the MOS
The source electrode of pipe Q1 connects the other end of the second resistance R2, and the metal-oxide-semiconductor Q1 is for controlling the switching power circuit 20.Institute
The source electrode for stating metal-oxide-semiconductor Q1 is also connected with the emitter of the second triode Q3.
Wherein, the first resistor R1 can select different temperature protection points according to different products, such as：Entire electricity
The temperature protection point of road plate needs within 90 degrees Celsius, so that it may to select temperature protection o'clock for 90 degrees Celsius of first resistor
R1, after the temperature on the peripheries first resistor R1 increases, when temperature reaches 90 degrees Celsius, the resistance value of first resistor R1 just becomes connecing
Nearly 0 resistance value or low resistance, the resistance of first resistor R1 become smaller, and electric current is caused to increase, to make the voltage of second resistance R2 increase,
Metal-oxide-semiconductor Q1 meetings unicom is directly forced by metal-oxide-semiconductor Q1 the first triode Q2 shutdowns, to turn off electricity when reaching certain threshold values
Source, and then protect entire Switching Power Supply 20 and related power device and load 300.After temperature lowers, first resistor
The resistance of R1 increases, and reverts to high impedance status, to which the electric conduction of metal-oxide-semiconductor Q1 is not achieved in the voltage at the both ends second resistance R2
Pressure, metal-oxide-semiconductor Q1 are disconnected, and the first triode Q2 can be with normal operation.
Specifically, the temperature control circuit 270 of crossing further includes：First capacitance C1 and third capacitance R3, first capacitance
The C1 second resistance R2 in parallel, for preventing external interference；The 3rd resistor R3 connects the drain electrode of the metal-oxide-semiconductor Q1, uses
In burning voltage.
In above-described embodiment, the switching circuit 280 includes：4th resistance R4, the 5th resistance R5, the 6th resistance R6,
Ten resistance R10, eleventh resistor R11, the 4th capacitance C4, the 5th capacitance C5, the first triode Q2, the second triode Q3；Wherein,
The base stage of the second triode Q3 is connect through the 6th resistance R6, the 5th resistance R5 with one end of the inductance L1 successively,
The collector of the second triode Q3 is connect with the Same Name of Ends of the primary side, and the emitter of the second triode Q3 is through institute
State eleventh resistor R11 ground connection；
One end of the 4th capacitance C4 connects the different name end of the auxiliary winding, the termination of the same name of the auxiliary winding
Ground；The collector of the first triode Q2 is connect with the base stage of the second triode Q3, the hair of the first triode Q2
The base stage of emitter grounding, the first triode Q2 connects through the emitter of the tenth resistance R10 and the second triode Q3
It connects.
In the present embodiment, the first triode Q2 and the second triode Q3 are NPN type triode, the MOS
Pipe Q1 is depletion type NMOS tube, and the first capacitance C1 is 104J63 or low capacity alminium electrolytic condenser.
In above-described embodiment, the feedback circuit 290 includes：Photo-coupler OC, zener diode D4, wherein the light
Coupler OC includes：Light emitting diode D5 and phototriode Q4；
In the present embodiment, the anode of the zener diode D4 connects the tenth capacitance C10, and cathode connection is described to shine
The cathode of diode D5, the anode of the light emitting diode D5 connect the cathode of the first diode D1；The phototriode Q4
Emitter ground connection, the collector of the phototriode Q4 connects the collector of the first triode Q2.
In the present embodiment, the tenth capacitance is that electrolytic capacitor becomes the pulsating dc voltage after rectification for filtering
Relatively steady dc voltage.
In the present embodiment, the luminescent device of the photo-coupler OC for transmitting analog signal is light emitting diode D5, light connects
Receipts device is phototriode Q4.When there is electric current by light emitting diode D5, a light source is just formed, which is irradiated to photosensitive
On the surfaces triode Q4, phototriode Q4 is set to generate collector current, the size of the electric current and the power of illumination, that is, flow through
The size of the forward current of light emitting diode D5 is directly proportional.Due to being believed by light between the input terminal and output end of photo-coupler OC
It number transmits, thus in electrically completely isolated, the not feedback of electric signal and interference between two parts, therefore performance is stablized, and resists
Interference performance is strong.
230 primary side of transformer terminal voltage of the same name is Vin, and 230 primary side of transformer terminal voltage of the same name is Nvin (N at this time
For turn ratio), 230 primary side Same Name of Ends voltage waveform of transformer is triangular wave, is obtained after output rectifier and filter 250
Vout；
When output voltage is higher than Vout, the electric current for flowing through zener diode D4 increases, the input terminal electricity of optocoupler and device OC
Stream also increases, and the output end current of optocoupler and device OC also increase at this time, and the base current to flow into the first triode Q2 reduces,
So that primary side is loading constant Vout reductions, to reach negative feedback, realization stabilizes the output voltage.Work as output
The first diode Q2 cut-offs, circuit just play overcurrent protection when electric current arrives greatly certain value.
In the present embodiment, the main function of photo-coupler OC is isolation, provides feedback signal and on-off action.Photo-coupler
The power supply of OC is provided from transformer-secondary voltage, when output voltage is less than the voltage of zener diode D4, photo-coupler
OC is connected, and increases duty ratio so that output voltage increases；It is on the contrary then turn off photo-coupler OC and reduce duty ratio so that output electricity
Pressure drop is low.And 300 overload of load or switching circuit 280 are faulty, are just provided without optocoupler power supply, photo-coupler OC is just controlled
Switching circuit 280 is unable to starting of oscillation, is burnt to protect switching tube to be unlikely to breakdown.
In the utility model embodiment, a kind of thermal-shutdown circuit is disclosed, including：Cross temperature control circuit and switch electricity
Source circuit, the temperature control circuit of crossing connect the switching power circuit；It is described cross temperature control circuit include：First resistor,
Two resistance, metal-oxide-semiconductor；The first resistor is the thermistor of negative temperature coefficient；The grid of the metal-oxide-semiconductor is connected to described first
The junction of resistance and the second resistance, the source electrode of the metal-oxide-semiconductor connect the other end of the second resistance.Pass through above-mentioned side
Formula, the utility model can solve the temperature for the heating power device that the prior art can not be in pilot switch power supply, and can not
The technical issues of temperature protection point being adjusted according to specific product.
It should be noted that giving the preferable implementation of the utility model in the specification and its attached drawing of the utility model
Mode, still, the utility model can be realized by many different forms, however it is not limited to which this specification is described to be implemented
Mode, these embodiments are not as the additional limitation to the utility model content, the purpose of providing these embodiments is that making
It is more thorough and comprehensive to the understanding of the disclosure of the utility model.Also, above-mentioned each technical characteristic continues to be combined with each other, and is formed
The various embodiments not being enumerated above are accordingly to be regarded as the range of the utility model specification record；Further, to this field
For those of ordinary skill, it can be modified or changed according to the above description, and all these modifications and variations should all belong to
The protection domain of the appended claims for the utility model.
Claims (10)
1. a kind of thermal-shutdown circuit, which is characterized in that including：Temperature control circuit and switching power circuit are crossed, it is described to cross temperature control
Circuit processed connects the switching power circuit；
It is described cross temperature control circuit include：First resistor, second resistance, metal-oxide-semiconductor；
The first resistor is the thermistor of negative temperature coefficient, and one end of the first resistor connects the second resistance, separately
One end connects the switching power circuit；
The grid of the metal-oxide-semiconductor is connected to the junction of the first resistor and the second resistance, and the source electrode of the metal-oxide-semiconductor connects
Connect the other end of the second resistance.
2. thermal-shutdown circuit according to claim 1, which is characterized in that it is described cross temperature control circuit further include：
First capacitance, first capacitance second resistance in parallel；
3rd resistor, the 3rd resistor connect the drain electrode of the metal-oxide-semiconductor.
3. thermal-shutdown circuit according to claim 1, which is characterized in that the thermal-shutdown circuit further includes：
Electromagnetic interface filter；
Input rectifying filter circuit；
Switching circuit connects the input rectifying filter circuit；
Transformer, including primary side, primary side and auxiliary winding；
Clamp circuit connects the input rectifying filter circuit and the transformer；
Output rectifier and filter connects the primary side of the transformer.
4. thermal-shutdown circuit according to claim 3, which is characterized in that the input rectifying filter circuit includes：It is whole
Flow bridge, the second capacitance, third capacitance and an inductance；Wherein, the zero line of one end of the electromagnetic interface filter and AC power connects
It connects, the other end of the electromagnetic interface filter connects the first input end of the rectifier bridge, the second input terminal connection of the rectifier bridge
First output end of the zero line side of AC power, the rectifier bridge is connect with one end of the inductance, and with second capacitance
One end connection, the other end of the inductance connect with one end of the third capacitance, the second output terminal of the rectifier bridge, institute
The other end of the other end, the third capacitance of stating the second capacitance is grounded.
5. thermal-shutdown circuit according to claim 4, which is characterized in that the clamp circuit includes：Second diode,
7th resistance, the 6th capacitance, the 8th resistance, the 9th resistance；Wherein, the anode of second diode connects the primary side
Same Name of Ends, the cathode of second diode connect one end of the 7th resistance, described in one end connection of the 6th capacitance
The other end of the other end of 7th resistance, the 6th capacitance connects the inductance, and the 6th is electric described in the 8th resistor coupled in parallel
Hold, the 8th resistance described in the 9th resistor coupled in parallel.
6. thermal-shutdown circuit according to claim 4, which is characterized in that the switching circuit includes：4th resistance,
Five resistance, the 6th resistance, the tenth resistance, eleventh resistor, the 4th capacitance, the 5th capacitance, the first triode, the second triode；
Wherein, the base stage of second triode is connect through the 6th resistance, the 5th resistance with one end of the inductance successively, described
The collector of second triode is connect with the Same Name of Ends of the primary side, and the emitter of second triode is through the described 11st
Resistance eutral grounding；
One end of 4th capacitance connects the different name end of the auxiliary winding, the Same Name of Ends ground connection of the auxiliary winding；It is described
The collector of first triode is connect with the base stage of second triode, the emitter ground connection of first triode, described
The base stage of first triode is connect through the tenth resistance with the emitter of second triode.
7. thermal-shutdown circuit according to claim 3, which is characterized in that the output rectifier and filter includes：The
One diode, the tenth capacitance, the 11st capacitance, the 14th resistance, wherein the tenth capacitance and the 11st capacitance are simultaneously
Connection, the anode of first diode and the Same Name of Ends of primary side connect, different name end of the cathode through the tenth capacitance and primary side
Connection；14th resistance is in parallel with the tenth capacitance, and the 14th resistance is in parallel with the 11st capacitance.
8. thermal-shutdown circuit according to claim 7, which is characterized in that the thermal-shutdown circuit further includes：Feedback
Circuit, wherein the feedback circuit includes：Photo-coupler, zener diode, wherein the photo-coupler includes：Light-emitting diodes
Pipe and phototriode；
The anode of the zener diode connects the tenth capacitance, and cathode connects the cathode of the light emitting diode, the hair
The anode of optical diode connects the cathode of the first diode；The emitter of the phototriode is grounded, the phototriode
Collector connect the first triode collector.
9. thermal-shutdown circuit according to claim 7, which is characterized in that the switching power circuit further includes：Output
Protection circuit, the output protection circuit include：8th capacitance, the cathode of one end and the tenth capacitance of the 8th capacitance
Connection, the other end ground connection of the 8th capacitance.
10. a kind of electronic equipment, which is characterized in that including such as claim 1-9 any one of them thermal-shutdown circuit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201820164516.3U CN207782395U (en) | 2018-01-30 | 2018-01-30 | A kind of thermal-shutdown circuit and electronic equipment |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201820164516.3U CN207782395U (en) | 2018-01-30 | 2018-01-30 | A kind of thermal-shutdown circuit and electronic equipment |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109480444A (en) * | 2018-12-10 | 2019-03-19 | 深圳和而泰智能控制股份有限公司 | A kind of Blowing drum |
| CN110995019A (en) * | 2018-10-02 | 2020-04-10 | 新唐科技股份有限公司 | Power driving chip and method |
| CN114384949A (en) * | 2021-12-08 | 2022-04-22 | 四方光电股份有限公司 | Temperature control circuit of gas sensing array and signal measurement circuit thereof |
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2018
- 2018-01-30 CN CN201820164516.3U patent/CN207782395U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110995019A (en) * | 2018-10-02 | 2020-04-10 | 新唐科技股份有限公司 | Power driving chip and method |
| CN110995019B (en) * | 2018-10-02 | 2021-07-23 | 新唐科技股份有限公司 | Power driving chip and method |
| CN109480444A (en) * | 2018-12-10 | 2019-03-19 | 深圳和而泰智能控制股份有限公司 | A kind of Blowing drum |
| CN109480444B (en) * | 2018-12-10 | 2024-04-09 | 深圳和而泰智能控制股份有限公司 | Blowing cylinder |
| CN114384949A (en) * | 2021-12-08 | 2022-04-22 | 四方光电股份有限公司 | Temperature control circuit of gas sensing array and signal measurement circuit thereof |
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