CN208753974U - A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit - Google Patents
A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit Download PDFInfo
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- CN208753974U CN208753974U CN201821404373.5U CN201821404373U CN208753974U CN 208753974 U CN208753974 U CN 208753974U CN 201821404373 U CN201821404373 U CN 201821404373U CN 208753974 U CN208753974 U CN 208753974U
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Abstract
The utility model provides a kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit, mainly includes overcurrent hiccup protections circuit, thermal-shutdown circuit, compensation level input, control terminal, feeder ear, ground terminal；Overcurrent hiccup protections circuit can make power supply automatically reply working condition when output electric current is excessive by power remove, and after certain time, that is, enter overcurrent hiccup protections state；Thermal-shutdown circuit can real-time detection temperature, by triggering overcurrent hiccup protections circuit by power remove, open, while using overcurrent hiccup protections circuit be added temperature hysteresis；Overtemperature and overcurrent protection can be realized using an operational amplifier and three terminal regulator TL431 in circuit, and circuit is simple, at low cost.
Description
Technical field:
The utility model relates to protection circuit field, in particular to a kind of overtemperature and overcurrent protects circuit and includes the circuit
Switching Power Supply.
Background technique:
Core component of the Switching Power Supply as modern transformation of electrical energy technology has been widely used in and various has used electric field
It closes, can Switching Power Supply safely and steadily run, it is directly related to the even personal safety of circuit safety, equipment safety, therefore
In Switching Power Supply design, protection circuit can all be added usually to ensure the safe and stable operation of power supply.
Switching Power Supply in use, when output power exceeds its rated power, not can guarantee its internal each device
Reliability, therefore output overcurrent protection and output short circuit protection circuit can usually be added to Switching Power Supply in the design process,
Guard method is generally divided into two ways: hiccup formula current foldback circuit and non-hiccup formula current foldback circuit.The protection of hiccup formula
Circuit operation principle are as follows: when Switching Power Supply opens machine, Switching Power Supply begins with power output, when power supply continues working a period of time
Afterwards, if being protected after output voltage cannot reach rated output voltage, or output electric current is persistently greater than maximum output current for a period of time
Protection circuit determines that power work in output overcurrent or output short-circuit state, protects circuit to turn off Switching Power Supply, power supply is not at this time
There is power output again, protection circuit starts timing, and when protection circuit timing reaches after a certain period of time, protection circuit exits protection shape
The restarting of state, i.e. Switching Power Supply, into next start-up course, completes a hiccup protections period, hiccup protections work side
Formula is widely used in many Switching Power Supplies, especially high power switching power supply equipment because of the advantages that low in energy consumption, highly reliable
In；Non- hiccup formula current foldback circuit working principle is usual are as follows: under switch power source output overcurrent or short-circuit condition, power supply there are still
Certain power output, output power neglect physical circuit and different, usually less than product rated output power, to guarantee
Switching Power Supply will not be damaged under output overcurrent or short-circuit condition because of overpower, open after overcurrent to be output or short trouble elimination
Powered-down source reenters normal operating conditions.
Switching Power Supply is power circuit, and temperature is influence Switching Power Supply component reliability and stability very important
Factor, temperature is excessively high will to will lead to many semiconductor devices (such as metal-oxide-semiconductor, triode), capacitor component damage, especially in ring
When border temperature is higher, along with the calorific value of Switching Power Supply itself, it is easy to so that electronic component is worked in high-temperature condition, accelerate
Power source aging even damages, therefore thermal-shutdown circuit is usually added into switching power circuit, makes Switching Power Supply component
Operating temperature controls within the range of permission, to guarantee its reliability and stability.Thermal-shutdown circuit, which generallys use, to be adopted
Collect heat-sensitive device external voltage or current signal, by comparing etc. modes be converted to controllable power switch telecommunications
Number, and be usually added into certain hysteresis, i.e., when Switching Power Supply temperature is more than certain higher set temperature, Switching Power Supply stops defeated
Out, when Switching Power Supply temperature is reduced to another lower set temperature, Switching Power Supply restarts work.
Common excess temperature, current foldback circuit because respectively requiring to generally use two circuits there are hysteresis and be implemented separately,
Common method is to be realized using two comparators, there are higher cost, accounts for the disadvantages of plate suqare is big.
Utility model content
In view of this, the utility model overcomes the above deficiency, a kind of overtemperature and overcurrent protection circuit is provided and comprising the circuit
Switching Power Supply, including overcurrent hiccup protections circuit, thermal-shutdown circuit, compensation level input, control terminal, feeder ear,
Line end.
Feeder ear connects overcurrent hiccup protections circuit and thermal-shutdown circuit simultaneously；The input terminal of overcurrent hiccup protections circuit
Level input is as compensated, the output end of overcurrent hiccup protections circuit is control terminal；
Thermal-shutdown circuit is connected by its triggering end with the end that is triggered of overcurrent hiccup protections circuit, overheat protector electricity
Road also passes through it and is pulled down end to be connected with the lower pull end of overcurrent hiccup protections circuit；Setting the inside overcurrent hiccup protections circuits
One setting value and the second setting value；
When compensate level input level raise to above or be equal to the first setting value when, overcurrent hiccup protections circuit it is defeated
Outlet exports low level, until when compensation level input level decreases below the second setting value, overcurrent hiccup protections circuit
Output end high-impedance state or hanging is presented, complete an overcurrent hiccup protections；
When temperature raises to above or is equal to the first setting value, thermal-shutdown circuit triggering end triggers overcurrent hiccup protections
Circuit, so that the level of the output end of overcurrent hiccup protections circuit is low level, at this time overcurrent hiccup protections by high level overturning
Thermal-shutdown circuit is pulled down end level by its lower pull end and dragged down by circuit, i.e., thermal-shutdown circuit enters depth protection shape
State；When temperature is reduced to the second setting value, thermal-shutdown circuit triggering end presentation high-impedance state or hanging, and overcurrent hiccup protections
The output end of circuit just exits guard mode after maintaining low level setting duration, i.e. the output end of overcurrent hiccup protections circuit at this time
High-impedance state or hanging is presented, completes an overheat protector.
Preferably, the first setting value is greater than the second setting value.
Preferably, overcurrent hiccup protections circuit includes: first resistor, second resistance, 3rd resistor, the 4th resistance, the 5th
Resistance, first diode, the second diode, third diode, the first operational amplifier, first capacitor；The compensation level is defeated
Enter the anode that end connects the first diode, the cathode of the first diode is through first resistor connection first fortune
The inverting input terminal of amplifier is calculated, the first operational amplifier inverting input terminal connects ground terminal by the 3rd resistor,
The first operational amplifier inverting input terminal also connects ground terminal, the first operational amplifier power supply through the first capacitor
End connects the feeder ear, and the first operational amplifier power ground connects the ground terminal, and the feeder ear is also through described the
Two resistance connect the first operational amplifier non-inverting input terminal, and the first operational amplifier non-inverting input terminal is through the described 4th
Resistance connects ground terminal, and the first operational amplifier non-inverting input terminal also connects the third diode through the 5th resistance
Anode, the cathode of the third diode connects first operational amplifier output terminal, and first operational amplifier is defeated
Outlet connects second diode cathode, and second diode anode connects the control terminal, and the first operational amplifier is anti-
It is the end that is triggered of overcurrent hiccup protections circuit to input terminal, the first operational amplifier output terminal is overcurrent hiccup protections circuit
Lower pull end.
Preferably, as the first scheme of thermal-shutdown circuit, comprising: the 6th resistance, the 7th resistance, the 8th resistance,
9th resistance, the first thermistor, the 4th diode, the 5th diode, the first three terminal regulator, feeder ear connect through the 6th resistance
The first three terminal regulator cathode is connect, the first three terminal regulator cathode connects the 4th diode anode, the first three terminal regulator anode
Ground terminal is connected, feeder ear also connects the anode of the 5th diode through the 7th resistance, and the 5th diode anode connects through the 8th resistance
Connecing the reference end of the first three terminal regulator, the first thermistor of reference end of the first three terminal regulator connects ground terminal, and the 4th
The cathode of diode is the triggering end of thermal-shutdown circuit, and the cathode of the 5th diode connects the 9th resistance one end, the 9th resistance
The other end is pulled down end for thermal-shutdown circuit；First thermistor is negative tempperature coefficient thermistor, i.e., when temperature increases,
Thermistor resistance value reduces, and when opposite thermal reduces, thermistor resistance value increases.
Preferably, the improvement as the first scheme of thermal-shutdown circuit further includes the tenth resistance, the tenth resistance
It connects with the first thermistor, i.e. the first thermistor of reference end, the tenth resistance of the first three terminal regulator connect ground terminal.
Preferably, another improvement as the first scheme of thermal-shutdown circuit further includes the second capacitor, the second capacitor one
The reference end of the first three terminal regulator of end connection, the other end of the second capacitor connect ground terminal.
Preferably, as the second scheme of thermal-shutdown circuit, comprising: the 6th resistance, the 7th resistance, the 8th resistance,
9th resistance, the second thermistor, the 4th diode, the 5th diode, the first three terminal regulator, feeder ear connect through the 6th resistance
The first three terminal regulator cathode is connect, the first three terminal regulator cathode connects the 4th diode anode, the first three terminal regulator anode
Ground terminal is connected, feeder ear also connects the anode of the 5th diode through the second thermistor, and the 5th diode anode is through the 8th electricity
The reference end of resistance the first three terminal regulator of connection, the 7th resistance of the reference end connection ground terminal of the first three terminal regulator, the 4th
The cathode of diode is the triggering end of thermal-shutdown circuit, and the cathode of the 5th diode connects the 9th resistance one end, the 9th resistance
The other end is pulled down end for thermal-shutdown circuit；Second thermistor is posive temperature coefficient thermistor, i.e., when temperature increases,
Thermistor resistance value increases, and when opposite thermal reduces, thermistor resistance value reduces.
Preferably, the improvement as thermal-shutdown circuit second scheme, further includes the second capacitor, and second capacitor one end connects
The reference end of the first three terminal regulator is connect, the other end of the second capacitor connects ground terminal.
Accordingly, the Switching Power Supply provided by the present application comprising above-mentioned overtemperature and overcurrent protection circuit, it is characterised in that:
It compensates level input level in Switching Power Supply output short-circuit or overcurrent to increase, the level when exporting electric current and reducing
It reduces；
Switching Power Supply stops working when control terminal is low level, and Switching Power Supply is resumed work when being high level.
Illustrate using the Switching Power Supply working principle of the utility model current foldback circuit:
In common Switching Converter Topologies, presence compensation level input Comp relevant to Voltage loop (or table
It is shown as FB), feature are as follows: at steady state, compensation level input level is a stable DC voltage, is exported in power supply
When electric current increases, compensation level input Comp (or FB) end level increases accordingly, on the contrary, mending when exporting electric current reduction
Repaying the end level input Comp (or FB) level accordingly reduces.
In the present invention, overcurrent hiccup protections circuit passes through detection compensation level input Comp (or being expressed as FB)
Voltage, be compared with its internal reference voltage, when electric power outputting current is excessive, compensation level input level is higher than
Internal reference voltage in overcurrent hiccup protections circuit, the control terminal of overcurrent hiccup protections circuit export low level, and power supply stops
Output enters guard mode；Overcurrent hiccup protections circuit has clocking capability, enters protection shape in overcurrent hiccup protections circuit
After state, by after a certain period of time, the control terminal output of overcurrent hiccup protections circuit shows as vacant state, i.e. control terminal voltage
For high level or high-impedance state, power supply rearming.
When temperature is increased to the first setting value, thermal-shutdown circuit triggers overcurrent hiccup protections circuit, and overcurrent hiccup is protected
Protection circuit control terminal exports low level, while thermal-shutdown circuit being made to enter depth guard mode, and Switching Power Supply stops working；When
When temperature is reduced to the second setting value, thermal-shutdown circuit exits depth guard mode, while triggering overcurrent hiccup protections circuit,
Make the control terminal high level or hanging of overcurrent hiccup protections circuit, Switching Power Supply restarts work.
The utility model has the beneficial effects that
1, thermal-shutdown circuit carries out controlling of sampling using three terminal regulator, and precision is high.
2, thermal-shutdown circuit introduces hysteresis using overcurrent hiccup protections circuit, when design can separately design overheat protector and
The temperature value of protection is exited, design return difference is easy to adjust.
3, two kinds of protections, circuit letter can be realized using a normal operation amplifier and a three terminal regulator in circuit
It is single, it is at low cost.
Detailed description of the invention
Fig. 1 is the principles of the present invention block diagram；
Fig. 2 is the schematic diagram of the utility model first embodiment；
Fig. 3 is the schematic diagram of the utility model second embodiment.
Specific embodiment
The technical concept of the utility model provides a kind of power supply overtemperature and overcurrent protection technique scheme, and feature is using one
A overcurrent hiccup protections circuit and a thermal-shutdown circuit, overcurrent hiccup protections circuit can realize power supply output overcurrent or short circuit
Under the conditions of hiccup protections, overheat protector work characteristics be in product excess temperature, thermal-shutdown circuit can trigger overcurrent hiccup
Circuit is protected, using overcurrent hiccup protections circuit by power remove, and meanwhile it is using overcurrent hiccup protections circuit that overheat protector is electric
Hysteresis is added in road, i.e., when product temperature is reduced to temperature more lower than overheat protector, thermal-shutdown circuit just exits guard mode,
Power supply restarts work.
The utility model is more clearly understood, it is with reference to the accompanying drawings and embodiments, further detailed to the utility model
Explanation.It should be pointed out that specific embodiment described herein is only used to explain the utility model, it is not used to limit originally practical
It is novel.
First embodiment
It is illustrated in figure 2 the schematic diagram of the utility model first embodiment, a kind of Switching Power Supply overtemperature and overcurrent protects circuit,
It is characterized by comprising first resistor R1, second resistance R2,3rd resistor R3, the 4th resistance R4, the 5th resistance R5, the 6th electricity
Hinder R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, first diode D1, the second diode D2, third diode D3,
4th diode D4, the 5th diode D5, the first operational amplifier AR1, first capacitor C1, the second capacitor C2, the one or three end are steady
Depressor TL431, the first thermistor RN；
The component that overcurrent hiccup protections circuit in the present embodiment includes are as follows: first resistor R1, second resistance R2,
Three resistance R3, the 4th resistance R4, the 5th resistance R5, first diode D1, the second diode D2, third diode D3, the first fortune
Calculate amplifier AR1, first capacitor C1；The component that thermal-shutdown circuit includes are as follows: the 6th resistance R6, the 7th resistance R7, the 8th
Resistance R8, the 9th resistance R9, the first thermistor RN, the 4th diode D4, the 5th diode D5, the second capacitor C2, the one or three
Hold voltage-stablizer TL431.
The connection relationship of the present embodiment are as follows: the anode of compensation level input Comp connection first diode D1, the one or two
Inverting input terminal of the cathode of pole pipe D1 through first resistor R1 the first operational amplifier of connection AR1, the first operational amplifier AR1 are anti-
Phase input terminal is also connected through first capacitor C1 by 3rd resistor R3 connection ground terminal, the first operational amplifier AR1 inverting input terminal
Grounding terminal, the first operational amplifier AR1 power end connect feeder ear Vcc, and the first operational amplifier AR1 power ground connects ground wire
End, feeder ear Vcc also connect the first operational amplifier AR1 non-inverting input terminal, the first same phase of operational amplifier AR1 through second resistance
Input terminal is through the 4th resistance R4 connection ground terminal, and the first operational amplifier AR1 non-inverting input terminal is also through the 5th resistance R5 connection
The cathode of the anode of three diode D3, third diode D3 connects the first operational amplifier AR1 output end, the first operational amplifier
AR1 output end connects the second diode D2 cathode, and the second diode D2 anode connects control terminal Ctrl, and feeder ear Vcc is through the 6th
Resistance R6 connection the first three terminal regulator TL431 cathode, the 4th diode D4 sun of the first three terminal regulator TL431 cathode connection
Pole, the 4th diode D4 cathode connect the first operational amplifier AR1 inverting input terminal, and the first three terminal regulator TL431 anode connects
Grounding terminal, anode of the feeder ear Vcc also through the 5th diode D5 of the 7th resistance R7 connection, the cathode of the 5th diode D5 is through
The output end of nine resistance R9 the first operational amplifier of connection AR1, the 5th diode D5 anode is through the 8th resistance R8 connection the one or three
The reference end of end voltage-stablizer TL431, reference end the first thermistor RN connection ground terminal of the first three terminal regulator TL431,
The reference end of first three terminal regulator TL431 is also through the second capacitor C2 connection ground terminal.
Its working principle is that:
Overcurrent hiccup protections circuit operation principle is, when electric power outputting current increases, compensation level input Comp electricity
Pressure increases, and is charged by diode D1, resistance R1 to capacitor C1, when capacitor C1 both end voltage is higher than between resistance R2 and R4
When voltage, operational amplifier AR1 output end voltage becomes low level from high level, and control terminal Ctrl level becomes low level, electricity
Source stops working；At this time because of the effect of resistance R5 and diode D3, operational amplifier AR1 non-inverting input terminal end voltage be pulled to compared with
Low voltage, since resistance R3 is in parallel with capacitor C1, the charge at the both ends capacitor C1 can be fallen by resistance R3 slow consumption, therefore electricity
Hold C1 both end voltage slowly to decline, when its voltage is decreased below operational amplifier AR1 non-inverting input terminal voltage, operation amplifier
Device AR1 exports high level, and an overcurrent hiccup protections are completed in power supply restarting.
Thermal-shutdown circuit working principle is that thermistor RN has negative temperature coefficient, i.e., when the temperature rises, temperature-sensitive electricity
It hinders resistance value to reduce, on the contrary, when the temperature decreases, thermistor resistance value increases.Due to resistance R7, resistance R8 and thermistor string
Connection, when temperature is lower, thermistor RN resistance value is larger, and the voltage that thermistor RN gets at both ends is greater than three terminal regulator
TL431 internal reference voltage (usually 2.5V or 1.25V), the electric current for flowing into anode from three terminal regulator TL431 cathode is larger,
Again because resistance R6 connects with three terminal regulator TL431, the voltage divided on resistance R6 is higher, therefore three terminal regulator TL431
Cathode voltage performance is low level, and diode D4 is in reverse blocking state, and the inverting input terminal voltage of operational amplifier AR1 is not
Influenced by thermal-shutdown circuit, under non-overcurrent protection state, operational amplifier AR1 export high level, control terminal Ctrl not by
It drags down, power supply is in running order；When the temperature increases, thermistor RN resistance value reduces, and the voltage at the both ends RN reduces, as RN two
When end voltage decreases below three terminal regulator TL431 internal reference voltage, three terminal regulator TL431 is in off state, i.e.,
The electric current that three terminal regulator TL431 cathode flows into is very small, and the electric current flowed out from Vcc through resistance R6 can be through diode D4 to capacitor
C1 charging, the voltage at the both ends capacitor C1 gradually rises, when the voltage at the both ends C1 raises to above the same mutually defeated of operational amplifier AR1
When entering to hold voltage, operational amplifier AR1 exports low level, and control terminal Ctrl voltage can be by operational amplifier AR1 output end through two
Pole pipe D2 is pulled to low level, and power supply stops working, that is, enters overheat protector state, at this time due to operational amplifier AR1 output end
For low level, the portion of electrical current for flowing through resistance R7 can flow into operational amplifier AR1 output end through diode D5 and resistance R9, this
When resistance R7 on electric current increase, the voltage on resistance R7 increases, and the voltage on resistance R8 and thermistor RN reduces at this time,
Even if the voltage on thermistor RN further decreases, circuit enters depth overheat protector state；Due to diode D5 and resistance
The shunting function of R9, the electric current flowed through on thermistor RN reduce, and circuit is to exit overheat protector state, the resistance of thermistor
Value need to increase to the resistance value than overheat protector Shi Geng great, i.e., when temperature decreases below the temperature of overheat protector, thermistor two
Voltage is held to be greater than three terminal regulator TL431 internal reference voltage, three terminal regulator TL431 cathode voltage reduces, on capacitor C1
Voltage gradually decreases under the consumption effect of resistance R3, decreases below the non-inverting input terminal voltage of operational amplifier AR1 always,
Product exits guard mode, and power supply restarts work.
On the basis of the present embodiment, capacitor C2 can be removed, the connection relationship of other components is constant, is also able to achieve this
The purpose of utility model.A resistance R10 can also be increased, resistance R10 connects with the first thermistor, i.e. the first three-terminal voltage-stabilizing
The first thermistor of reference end, the resistance R10 connection ground terminal of device, are similarly able to achieve the purpose of this utility model.
Second embodiment
It is illustrated in figure 3 the schematic diagram of the utility model second embodiment, a kind of Switching Power Supply overtemperature and overcurrent protects circuit,
It is characterized by comprising first resistor R1, second resistance R2,3rd resistor R3, the 4th resistance R4, the 5th resistance R5, the 6th electricity
Hinder R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, first diode D1, the second diode D2, third diode D3,
4th diode D4, the 5th diode D5, the first operational amplifier AR1, first capacitor C1, the second capacitor C2, the one or three end are steady
Depressor TL431, the second thermistor RP；
The component that overcurrent hiccup protections circuit in the present embodiment includes are as follows: first resistor R1, second resistance R2,
Three resistance R3, the 4th resistance R4, the 5th resistance R5, first diode D1, the second diode D2, third diode D3, the first fortune
Calculate amplifier AR1, first capacitor C1；The component that thermal-shutdown circuit includes are as follows: the 6th resistance R6, the 7th resistance R7, the 8th
Resistance R8, the 9th resistance R9, the second thermistor RP, the 4th diode D4, the 5th diode D5, the second capacitor C2, the one or three
Hold voltage-stablizer TL431.
The connection relationship of the present embodiment are as follows: the anode of compensation level input Comp connection first diode D1, the one or two
Inverting input terminal of the cathode of pole pipe D1 through first resistor R1 the first operational amplifier of connection AR1, the first operational amplifier AR1 are anti-
Phase input terminal is also connected through first capacitor C1 by 3rd resistor R3 connection ground terminal, the first operational amplifier AR1 inverting input terminal
Grounding terminal, the first operational amplifier AR1 power end connect feeder ear Vcc, and the first operational amplifier AR1 power ground connects ground wire
End, feeder ear Vcc also connect the first operational amplifier AR1 non-inverting input terminal, the first same phase of operational amplifier AR1 through second resistance
Input terminal is through the 4th resistance R4 connection ground terminal, and the first operational amplifier AR1 non-inverting input terminal is also through the 5th resistance R5 connection
The cathode of the anode of three diode D3, third diode D3 connects the first operational amplifier AR1 output end, the first operational amplifier
AR1 output end connects the second diode D2 cathode, and the second diode D2 anode connects control terminal Ctrl, and feeder ear Vcc is through the 6th
Resistance R6 connection the first three terminal regulator TL431 cathode, the 4th diode D4 sun of the first three terminal regulator TL431 cathode connection
Pole, the 4th diode D4 cathode connect the first operational amplifier AR1 inverting input terminal, and the first three terminal regulator TL431 anode connects
Grounding terminal, anode of the feeder ear Vcc also through the 5th diode D5 of the second thermistor RP connection, the cathode of the 5th diode D5
Output end through the 9th resistance R9 the first operational amplifier of connection AR1, the 5th diode D5 anode is through the 8th resistance R8 connection
The reference end of one three terminal regulator TL431, the 7th resistance R7 connection ground terminal of reference end of the first three terminal regulator TL431,
The reference end of first three terminal regulator TL431 is also through the second capacitor C2 connection ground terminal.
Overcurrent hiccup protections circuit part circuit operation principle is identical as first embodiment principle, and which is not described herein again, with
First embodiment the difference is that, anode of the feeder ear Vcc through the 5th diode D5 of the second thermistor RP connection, the one or three
The 7th resistance R7 connection ground terminal of reference end of voltage-stablizer TL431 is held, thermistor RP is negative tempperature coefficient thermistor, when
When temperature increases, the resistance value of thermistor RP increases, since thermistor RP and resistance R8 and resistance R7 is series relationship, temperature-sensitive
Resistance RP resistance value increases, and the electric current for flowing through thermistor RP, resistance R8 and resistance R7 reduces, and the voltage on resistance R7 reduces, when
When temperature is increased to the first setting value, voltage drop on resistance R7 down to three terminal regulator TL431 internal reference hereinafter, three ends
The cathode voltage of voltage-stablizer increases, and thermal-shutdown circuit triggers overcurrent hiccup protections circuit, and power supply enters overheat protector；Work as temperature
When being reduced to the second setting value, voltage drop on resistance R7 down to three terminal regulator TL431 internal reference hereinafter, three ends are steady
The cathode voltage of depressor reduces, and thermal-shutdown circuit exits guard mode, power supply restarting.
On the basis of the present embodiment, capacitor C2 can be removed, the connection relationship of other components is constant, is also able to achieve this
The purpose of utility model.
Above are merely preferred embodiments of the utility model, it is noted that above-mentioned preferred embodiment should not regard
For limitations of the present invention, for those skilled in the art, in the essence for not departing from the utility model
In mind and range, several improvements and modifications can also be made, these improvements and modifications also should be regarded as the protection model of the utility model
It encloses, is no longer repeated here with example, the protection scope of the utility model should be defined by the scope defined by the claims..
Claims (8)
1. a kind of overtemperature and overcurrent protects circuit, it is characterised in that: including overcurrent hiccup protections circuit, thermal-shutdown circuit, compensation
Level input, control terminal, feeder ear, ground terminal；
Feeder ear connects overcurrent hiccup protections circuit and thermal-shutdown circuit simultaneously；The input terminal of overcurrent hiccup protections circuit is
Level input is compensated, the output end of overcurrent hiccup protections circuit is control terminal；
Thermal-shutdown circuit is connected by its triggering end with the end that is triggered of overcurrent hiccup protections circuit, and thermal-shutdown circuit is also
End is pulled down by it to be connected with the lower pull end of overcurrent hiccup protections circuit；Setting first is set inside overcurrent hiccup protections circuit
Definite value and the second setting value；
When compensation level input level raises to above or is equal to the first setting value, the output end of overcurrent hiccup protections circuit
Export low level, until compensation level input level is when decreasing below the second setting value, overcurrent hiccup protections circuit it is defeated
High-impedance state or hanging is presented in outlet, completes an overcurrent hiccup protections；
When temperature raises to above or is equal to the first setting value, thermal-shutdown circuit triggering end triggers overcurrent hiccup protections electricity
Road, so that the level of the output end of overcurrent hiccup protections circuit is low level by high level overturning, overcurrent hiccup protections are electric at this time
Thermal-shutdown circuit is pulled down end level by its lower pull end and dragged down by road, i.e., thermal-shutdown circuit enters depth guard mode；
When temperature is reduced to the second setting value, high-impedance state or hanging is presented in thermal-shutdown circuit triggering end, and overcurrent hiccup protections are electric
The output end on road just exits guard mode after maintaining low level setting duration, i.e., the output end of overcurrent hiccup protections circuit is at this time
Existing high-impedance state is hanging, completes an overheat protector.
2. overtemperature and overcurrent according to claim 1 protects circuit, it is characterised in that: first setting value is greater than described
The second setting value.
3. overtemperature and overcurrent according to claim 2 protects circuit, it is characterised in that: the overcurrent hiccup protections circuit packet
It includes: first resistor, second resistance, 3rd resistor, the 4th resistance, the 5th resistance, first diode, the second diode, the three or two
Pole pipe, the first operational amplifier, first capacitor；The compensation level input connects the anode of the first diode, described
The cathode of first diode connects the inverting input terminal of first operational amplifier, first operation through the first resistor
Amplifier inverting input terminal connects ground terminal by the 3rd resistor, and the first operational amplifier inverting input terminal is also through institute
First capacitor connection ground terminal is stated, the first operational amplifier power end connects the feeder ear, first operation amplifier
Device power ground connects the ground terminal, and the feeder ear also connects first operational amplifier with mutually defeated through the second resistance
Enter end, the first operational amplifier non-inverting input terminal connects ground terminal, first operational amplifier through the 4th resistance
Non-inverting input terminal also connects the anode of the third diode through the 5th resistance, and the cathode of the third diode connects institute
State the first operational amplifier output terminal, first operational amplifier output terminal connects second diode cathode, and described the
Two diode anodes connect the control terminal, and the first operational amplifier reverse input end is being triggered for overcurrent hiccup protections circuit
End, the first operational amplifier output terminal are the lower pull end of overcurrent hiccup protections circuit.
4. overtemperature and overcurrent according to claim 2 protects circuit, it is characterised in that: the thermal-shutdown circuit includes:
6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the first thermistor, the 4th diode, the 5th diode, the one or three
Voltage-stablizer is held, feeder ear connects the first three terminal regulator cathode, the first three terminal regulator cathode connection the four or two through the 6th resistance
Pole pipe anode, the first three terminal regulator anode connect ground terminal, and feeder ear also connects the anode of the 5th diode through the 7th resistance,
5th diode anode connects the reference end of the first three terminal regulator through the 8th resistance, the reference end of the first three terminal regulator the
One thermistor connects ground terminal, and the cathode of the 4th diode is the triggering end of thermal-shutdown circuit, the cathode of the 5th diode
The 9th resistance one end is connected, the 9th resistance other end is pulled down end for thermal-shutdown circuit；First thermistor is negative temperature
When coefficient resistance, i.e. temperature increase, thermistor resistance value reduces, and when opposite thermal reduces, thermistor resistance value increases.
5. overtemperature and overcurrent according to claim 4 protects circuit, it is characterised in that: the thermal-shutdown circuit further includes
Tenth resistance, the tenth resistance are connected with the first thermistor, i.e. the first temperature-sensitive of reference end of the first three terminal regulator
Resistance, the tenth resistance connect ground terminal.
6. overtemperature and overcurrent according to claim 2 protects circuit, it is characterised in that: the thermal-shutdown circuit includes:
6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, the second thermistor, the 4th diode, the 5th diode, the one or three
Voltage-stablizer is held, feeder ear connects the first three terminal regulator cathode, the first three terminal regulator cathode connection the four or two through the 6th resistance
Pole pipe anode, the first three terminal regulator anode connect ground terminal, and feeder ear also connects the 5th diode through the second thermistor
Anode, the 5th diode anode connect the reference end of the first three terminal regulator, the reference of the first three terminal regulator through the 8th resistance
End connects ground terminal through the 7th resistance, and the cathode of the 4th diode is the triggering end of thermal-shutdown circuit, the yin of the 5th diode
Pole connects the 9th resistance one end, and the 9th resistance other end is pulled down end for thermal-shutdown circuit；Second thermistor is positive temperature
Coefficient resistance is spent, i.e., when temperature increases, thermistor resistance value increases, and when opposite thermal reduces, thermistor resistance value reduces.
7. protecting circuit according to overtemperature and overcurrent described in claim 4 or 5 or 6, it is characterised in that: the thermal-shutdown circuit
It further include the second capacitor, second capacitor one end connects the reference end of the first three terminal regulator, and the other end of the second capacitor connects ground
Line end.
8. a kind of Switching Power Supply comprising the protection circuit of overtemperature and overcurrent described in the claims 1, it is characterised in that: compensation electricity
Flat input terminal level in Switching Power Supply output short-circuit or overcurrent increases, and when switch power supply output current reduces, level is reduced；
Switching Power Supply stops working when control terminal is low level, and Switching Power Supply is resumed work when control terminal is high level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821404373.5U CN208753974U (en) | 2018-08-29 | 2018-08-29 | A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201821404373.5U CN208753974U (en) | 2018-08-29 | 2018-08-29 | A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit |
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| Publication Number | Publication Date |
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| CN208753974U true CN208753974U (en) | 2019-04-16 |
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| CN201821404373.5U Active CN208753974U (en) | 2018-08-29 | 2018-08-29 | A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108988298A (en) * | 2018-08-29 | 2018-12-11 | 广州金升阳科技有限公司 | A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit |
-
2018
- 2018-08-29 CN CN201821404373.5U patent/CN208753974U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108988298A (en) * | 2018-08-29 | 2018-12-11 | 广州金升阳科技有限公司 | A kind of overtemperature and overcurrent protection circuit and the Switching Power Supply comprising the circuit |
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