CN206041465U - Switching power supply circuit with over-temperature protection - Google Patents
Switching power supply circuit with over-temperature protection Download PDFInfo
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- CN206041465U CN206041465U CN201621050842.9U CN201621050842U CN206041465U CN 206041465 U CN206041465 U CN 206041465U CN 201621050842 U CN201621050842 U CN 201621050842U CN 206041465 U CN206041465 U CN 206041465U
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Abstract
The utility model discloses a switching power supply circuit with over-temperature protection, which comprises a power input end, a load access end, a power circuit, a constant current control circuit and an over-temperature protection circuit; the power supply input end is connected with the voltage input end of the power supply circuit; the voltage output end of the power supply circuit is connected with the input end of the constant current control circuit; the output end of the constant current control circuit is connected with the load access end; the electric signal output end of the temperature sampling unit in the over-temperature protection circuit is connected with the base electrode of the triode; the emitting electrode of the triode is grounded, and the collecting electrode of the triode is connected with the reference end of the constant current control circuit. The utility model discloses can regulate and control switching power supply's output according to current temperature self-adaptation ground when ambient temperature changes, make the load keep work with one and current temperature assorted working parameter in the temperature variation process, also make switching power supply's inside temperature and ambient temperature reach a thermal balance, can effectively reduce power itself and load because of the damaged probability of excess temperature, and improved user experience.
Description
Technical field
This utility model is related to electronic technology field, more particularly to a kind of switching power circuit with overheat protector.
Background technology
For Switching Power Supply, when ambient temperature is too high, power supply itself and load is easily caused to damage.In this regard, needing
Thermal-shutdown circuit is set up in Switching Power Supply, for making protection act detecting when temperature reaches temperature threshold, in case
Only power supply itself and load because excess temperature damage and cisco unity malfunction.
At present, in most Switching Power Supplies, series arm is constituted using a conventional, electric-resistance and a critesistor, electricity is formed
Resistance potentiometer, and the former limit power control circuit of the common node connecting valve power supply of the conventional, electric-resistance and the critesistor
Test side, realize the overheat protector of Switching Power Supply with this.Specifically, by the voltage at the common node characterizing inspection
The temperature for measuring, power control circuit detect the voltage at the common node, when detecting the voltage at the common node
When reaching higher limit, that is, represent that temperature has been raised to temperature threshold, then directly controlling switch power remove output, stop as load
Power supply.
However, the present inventor is during this utility model is implemented, it is found that prior art has problems with, in environment
During temperature change, as long as temperature does not rise to threshold value, Switching Power Supply does not just take any regulation measure, however, working as
When temperature rises to threshold value, then directly shut-off output.Thus, when ambient temperature is higher but is also not reaching to threshold value,
Still with full power carry load work, this may cause ambient temperature further to raise to Switching Power Supply, be unfavorable for Switching Power Supply
Normal work, for example, when the load that Switching Power Supply is accessed is LED light emitting diodes, anti-phase electric leakage is electric at high temperature for diode
Stream is bigger, can produce more heats.In addition, there is the defect of frequently shut-off near overheat protector point, so it is easily damaged
Power supply itself and load, and Consumer's Experience is not good.
Utility model content
Technical problem to be solved in the utility model is, there is provided a kind of switching power circuit with overheat protector, energy
Enough in variation of ambient temperature, adaptively its output is regulated and controled according to Current Temperatures so that be supported on temperature change
The running parameter holding work matched with Current Temperatures with one during change, meanwhile, also so that the inside temperature of Switching Power Supply
Degree and ambient temperature reach a thermal balance, can be effectively reduced power supply itself and load because of excess temperature impaired probability,
And improve Consumer's Experience.
In order to solve above-mentioned technical problem, the utility model proposes a kind of switching power circuit with overheat protector, bag
Include power input, load incoming end, power circuit, constant-current control circuit and thermal-shutdown circuit；
The power circuit has voltage input end and voltage output end；The constant-current control circuit has input, defeated
Go out end and reference edge；
The power input connects the voltage input end of the power circuit；The voltage output end of the power circuit connects
Connect the input of the constant-current control circuit；The outfan of the constant-current control circuit connects the load incoming end；
The thermal-shutdown circuit includes temperature sampling unit and audion；The temperature sampling unit has the signal of telecommunication defeated
Go out end, earth terminal and the feeder ear for accessing DC power signal；The electrical signal connects the base of the audion
Pole；The grounded emitter of the audion, the colelctor electrode of the audion connect the reference edge of the constant-current control circuit.
Preferably, the thermal-shutdown circuit also includes first resistor and second resistance；
The first resistor is connected across between the base stage of the audion and emitter stage；Also,
The electrical signal of the temperature sampling unit connects the base stage of the audion, specially：
The electrical signal of the temperature sampling unit connects the base stage of the audion by the second resistance.
In one preferred embodiment, the temperature sampling unit also includes being made up of 3rd resistor and critesistor
Series arm；
The first end of the series arm is the feeder ear of the temperature sampling unit, and the 3rd in the series arm is electric
The common node of resistance and critesistor is the electrical signal of the temperature sampling unit, and the second end of the series arm is
The earth terminal of the temperature sampling unit.
Preferably, the first end of the 3rd resistor is the first end of the series arm, the second of the 3rd resistor
The first end of the end connection critesistor, the second end of the critesistor is the second end of the series arm.
Further, the critesistor is semistor, and the audion is NPN triode.
Further, the critesistor is negative tempperature coefficient thermistor, and the audion is PNP triode.
Preferably, the first end of the critesistor is the first end of the series arm, the second of the critesistor
The first end of the end connection 3rd resistor, the second end of the 3rd resistor is the second end of the series arm.
Further, the critesistor is negative tempperature coefficient thermistor, and the audion is NPN triode.
Further, the critesistor is semistor, and the audion is PNP triode.
Another preferred embodiment in, the temperature sampling unit also includes that 3rd resistor and integrated temperature are sensed
Device；The integrated temperature sensor has positive power source terminal, electrical signal and negative power end；
The first end of the 3rd resistor is the feeder ear of the temperature sampling unit, and the second end of the 3rd resistor connects
Connect the positive power source terminal of the integrated temperature sensor；The electrical signal of the integrated temperature sensor is the temperature sampling
The electrical signal of unit, the negative power end are the earth terminal of the temperature sampling unit.
Further, the integrated temperature sensor is positive temperature coefficient temperature sensor, and the audion is NPN tri-
Pole pipe.
Implement this utility model, have the advantages that：
The switching power circuit with overheat protector that this utility model embodiment is provided, arranges thermal-shutdown circuit, including
Temperature sampling unit and audion, wherein, the base stage of the electrical signal connecting triode of temperature sampling unit, audion
Grounded emitter, colelctor electrode connect the reference edge of constant-current control circuit；And by the voltage output end connection constant current of power circuit
The input of control circuit, the outfan connection load incoming end of constant-current control circuit, can be in variation of ambient temperature, by mistake
The input voltage of the reference edge of the colelctor electrode control constant-current control circuit of the audion in warm protection circuit, and then according to current temperature
Degree adaptively regulates and controls to the output of Switching Power Supply so that what constant-current control circuit was connect is supported on temperature change mistake
The running parameter holding work matched with Current Temperatures with one in journey, meanwhile, also so that the internal temperature of Switching Power Supply and
Ambient temperature reaches a thermal balance, can be effectively reduced power supply itself and load because of excess temperature impaired probability, and carry
High Consumer's Experience.
Description of the drawings
Fig. 1 is the structural representation of the one embodiment for the switching power circuit with overheat protector that this utility model is provided
Figure；
Fig. 2 is the structural representation of second embodiment of the switching power circuit with overheat protector that this utility model is provided
Figure；
Fig. 3 is the structural representation of the 3rd embodiment of the switching power circuit with overheat protector that this utility model is provided
Figure；
Fig. 4 is the structural representation of the 4th embodiment of the switching power circuit with overheat protector that this utility model is provided
Figure；
Fig. 5 is the structural representation of the 5th embodiment of the switching power circuit with overheat protector that this utility model is provided
Figure.
Specific embodiment
Below in conjunction with the accompanying drawing in this utility model embodiment, the technical scheme in this utility model embodiment is carried out
Clearly and completely describe, it is clear that described embodiment is only this utility model a part of embodiment, rather than whole
Embodiment.Based on the embodiment in this utility model, those of ordinary skill in the art are not under the premise of creative work is made
The every other embodiment for being obtained, belongs to the scope of this utility model protection.
Fig. 1 is referred to, is the knot of the one embodiment for the switching power circuit with overheat protector that this utility model is provided
Structure schematic diagram.
The switching power circuit with overheat protector that the present embodiment is provided, including power input VIN, load incoming end
Load, power circuit 10, constant-current control circuit 20 and thermal-shutdown circuit 30；
The power circuit 10 has voltage input end and voltage output end；The constant-current control circuit 20 has input
End, outfan and reference edge；
The power input VINConnect the voltage input end of the power circuit 10；The voltage of the power circuit 10 is defeated
Go out the input that end connects the constant-current control circuit 20；The outfan connection load of the constant-current control circuit 20 is accessed
End Load；
The thermal-shutdown circuit 30 includes temperature sampling unit 31 and audion 32；The temperature sampling unit 31 has
Electrical signal, earth terminal and the feeder ear V for accessing DC power signalCC；The electrical signal connection is described
The base stage of audion 32；The grounded emitter of the audion 32, the colelctor electrode of the audion 32 connect the current constant control
The reference edge of circuit 20.
Wherein, power input VINFor incoming transport power supply signal, such as civil power；On the one hand load incoming end Load connects
The outfan of constant-current control circuit 20 is connect, and on the other hand for connecting load, constant electric current is provided by the load for connecting.
In the present embodiment, for power circuit 10, there are various topological structures available.Preferably, power circuit 10 is gone back
Including input rectifying filter circuit, primary side switch control circuit, power conversion circuit, main transformer, output rectifier and filter
And feedback voltage stabilizing circuit, wherein, the input of input rectifying filter circuit is the voltage input end of power circuit 10, exports rectification
Voltage output end of the outfan of filter circuit for power circuit 10, and the company of the unit circuit in above-mentioned power circuit 10
Connect relation and function is prior art, be not added with herein repeating.
In the present embodiment, for thermal-shutdown circuit 30, the feeder ear V of its temperature sampling unit 31CC, it is straight for accessing
Stream power supply signal, is that temperature sampling unit 31 provides running voltage, it should be noted that the DC power signal can be by switching
The voltage output end of the power circuit 10 of power source internal is provided, or, it is also possible to provided by the power supply outside Switching Power Supply.
In addition, temperature sampling unit 31 includes temperature-sensing element (such as critesistor or integrated temperature sensor), temperature-sensing element
For the change of detection temperature, and the change of temperature is converted into into the attribute change of its own, and then causes temperature sampling unit
The voltage signal that 31 electrical signal output is matched with Current Temperatures is to the audion 32 in thermal-shutdown circuit 30
Base stage.Specifically, when temperature is increased to limit work(temperature value, the voltage signal of the output of temperature sampling unit 31 causes audion 32
Base stage and emitter stage between voltage difference can match the emitter junction conducting voltage of audion 32, and cause audion 32 corresponding
Conducting, subsequently, if temperature is further raised, the voltage signal of the output of temperature sampling unit 31 causes audion 32 further to lead
It is logical；And, when temperature is less than limit work(temperature value, the voltage signal of the output of temperature sampling unit 31 causes the base stage of audion 32
Voltage difference and emitter stage between cannot match the emitter junction conducting voltage of audion 32, and then audion 32 is ended.
In addition, the audion 32 in thermal-shutdown circuit 30 is increased to limit for detecting temperature in temperature sampling unit 31
During work(temperature value, correspondingly turn on, and then correspondingly drag down the input electricity of the reference edge of constant-current control circuit 20 by colelctor electrode
Pressure；Also, after temperature reaches limit work(temperature value, if temperature still persistently rises, audion 32 is further turned on, audion
32 colelctor electrode further drags down the input voltage of the reference edge of constant-current control circuit 20.And, in temperature less than limit work(temperature
During value, audion 32 ends, and the output of its colelctor electrode does not affect the input voltage of the reference edge of constant-current control circuit 20.
In the present embodiment, for constant-current control circuit 20, there are various topological structures available.Preferably, current constant control
Circuit 20 includes power tube, current constant control chip and its peripheral circuit, and the reference edge of constant-current control circuit 20 can be current constant control
The ISET pins of chip, REF pins or FB pins, in addition, the company of the unit circuit in above-mentioned constant-current control circuit 20
Connect relation and function is prior art, be not added with herein repeating.Specifically, when the input electricity of the reference edge of constant-current control circuit 20
When pressure is pulled low, then the GATE pins for triggering the current constant control chip in constant-current control circuit 20 export corresponding PWM controls letter
Number, the ratio of the conducting and cut-off of power tube is controlled, to adjust the running parameter of connected load, reduces the defeated of Switching Power Supply
Go out power, reduce the heating of Switching Power Supply, then, if the input voltage of the reference edge of constant-current control circuit 20 is further drawn
It is low, when reference edge input voltage less than threshold value when, triggering current constant control chip quit work so that constant-current control circuit 20
Shut-off output, stops the load supplying by connecting.And, if the input voltage of reference edge gos up, trigger current constant control
The GATE pins of chip export corresponding pwm control signal, control the ratio of the conducting and cut-off of power tube, what adjustment was connected
The running parameter of load, and the output of adaptive increase Switching Power Supply.
It should be noted that switching power circuit can include multiple secondary windings including multiple-channel output, i.e. main transformer,
Each secondary windings connects an output rectifier and filter, then the outfan of each output filter circuit can connect load,
And then be different load supplyings, if in addition, load is when needing constant current to work, need to be in the outfan of current rectifying and wave filtering circuit
Constant-current control circuit is set up and load between.The switching power circuit of tv product is applied to for example, its main transformer may include
Two secondary windings, i.e. two-way are exported, and one of secondary windings connect constant-current control circuit by output rectifier and filter
20 input, and the outfan connection LED string of constant-current control circuit 20, provide constant operating current for LED string, its
In, LED string is the back light of display, and another secondary windings is directly connected to TV motherboard by output filter circuit
With loudspeaker etc., it is that mainboard and loudspeaker provide constant running voltage, in this switching power circuit, if by thermal-shutdown circuit 30
In the colelctor electrode of audion 32 be connected to the control port of the primary side switch control circuit in power circuit 10, work as temperature change
When, the output of whole Switching Power Supply is regulated and controled according to the input signal of the control port of primary side switch control circuit, however, by
It is quite big in the uncertainty of the power of loudspeaker load, i.e., with sound variation, its changed power very greatly and quickly, therefore, each road
Load is difficult to find the running parameter matched with Current Temperatures, and then, it is difficult to realize the internal temperature and environment of Switching Power Supply
Temperature reaches a thermal balance.However, for LED, in its course of work, its power is relatively stable, therefore, incited somebody to action
The colelctor electrode of the audion 32 in warm protection circuit 30 is connected to the reference edge of constant-current control circuit 20, when the temperature is changed, root
Regulate and control the running parameter of LED load, and then the adaptive change of output of Switching Power Supply according to the input signal of reference edge,
In regulation process, LED load can easily find the running parameter matched with Current Temperatures, and then, it is easy to accomplish Switching Power Supply it is interior
Portion's temperature and ambient temperature reach a thermal balance.
The operation principle with overheat protector switching power circuit that the present embodiment is provided is as follows：
When ambient temperature is normal, the audion 32 in thermal-shutdown circuit 30 is in cut-off state, does not affect power supply electricity
Road 10 and the normal work of constant-current control circuit 20；When ambient temperature is raised, the signal of telecommunication of the output of temperature sampling unit 31
Respective change, so audion 32 base stage and emitter stage between voltage difference respective change, when ambient temperature is increased to limit work(
During temperature value, the voltage difference is matched with the emitter junction conducting voltage of audion 32, and audion 32 is corresponding to be turned on, current constant control electricity
The input voltage of the reference edge on road 20 is accordingly dragged down, and the electric current for flowing through load accordingly reduces, the output phase of Switching Power Supply
Should reduce, the heating of Switching Power Supply is reduced, subsequently, if the temperature of Switching Power Supply has declined, the base of constant-current control circuit 20
The input voltage at quasi- end gos up, and the electric current for flowing through load accordingly increases, and the output of Switching Power Supply accordingly increases, with such
Push away, until the running parameter of load is adjusted to match with current environmental temperature so that be supported in temperature changing process with
The one running parameter holding work matched with Current Temperatures, also so that the internal temperature of Switching Power Supply and ambient temperature reach
One thermal balance.In addition, if ambient temperature is more severe, when temperature still persistently rises after limit work(temperature value is reached, then three pole
Pipe 32 is further turned on, and further drags down the input voltage of the reference edge of constant-current control circuit 20, when temperature reaches temperature threshold
When, the input voltage of the reference edge of constant-current control circuit 20 is pulled down to less than voltage threshold so that constant-current control circuit 20 is closed
Disconnected output, stops the load supplying by connecting.
Fig. 2 is referred to, is second embodiment of the switching power circuit with overheat protector that this utility model is provided
Structural representation.
On the basis of above-mentioned one embodiment, it is preferable that the thermal-shutdown circuit 30 also includes first resistor R1
With second resistance R2；First resistor R1 is connected across between the base stage of the audion 32 and emitter stage；Also, the temperature
The electrical signal of sampling unit 31 connects the base stage of the audion 32, specially：The electricity of the temperature sampling unit 31
Signal output part connects the base stage of the audion 32 by second resistance R2.
It should be noted that in the present embodiment, first resistor R1 and second resistance R2 are for temperature sampling unit 31
The voltage of output carries out partial pressure, and the resistance for adjusting the two resistance can be realized needing to set to limiting work(temperature value according to user
Put, such as, when setting limit work(temperature value is 120 DEG C, i.e., when temperature reaches 120 DEG C, start to reduce the output work of Switching Power Supply
Rate.That is, need to meet at 120 DEG C, the voltage to the output of temperature sampling unit 31 of first resistor R1 and second resistance R2 is carried out
Partial pressure as a result, the voltage at first resistor R1 two ends, i.e. voltage difference between the base stage of audion 32 and emitter stage can
Emitter junction conducting voltage with audion 32, and then cause audion 32 to be switched to corresponding conducting state from cut-off state, three
32 colelctor electrode of pole pipe starts the input voltage of the reference edge for accordingly dragging down constant-current control circuit 20, and then passes through the electricity of load
Stream is corresponding to be reduced, and the output of Switching Power Supply accordingly reduces, and the heating of Switching Power Supply is reduced.If also, arranging temperature threshold
For 150 DEG C, i.e., when temperature reaches 150 DEG C, stop by connecing load supplying.That is, need to meet at 150 DEG C, first resistor R1
With second resistance R2 the voltage of the output of temperature sampling unit 31 is carried out partial pressure as a result, the electricity at first resistor R1 two ends
Pressure, i.e., the voltage difference between the base stage of audion 32 and emitter stage can match the emitter junction conducting voltage of audion 32, and then
So that audion 32 is further turned on, 32 colelctor electrode of audion further drags down the input electricity of the reference edge of constant-current control circuit 20
Pressure, and cause the low threshold value for turning off output to constant-current control circuit 20 of input voltage of reference edge.
In the present embodiment, work(temperature can be limited by adjusting the resistance of first resistor R1 and second resistance R2 to adjust
Value, does not so interfere with the precision and stability of sample temperature, effectively raises the reliability of circuit；Meanwhile, set up first
After resistance R1 and second resistance R2 carry out partial pressure so that the thermal-shutdown circuit 30 can compatible different temperature-sensing element, have
The compatibility that improve circuit of effect.
Fig. 3 is referred to, is the 3rd embodiment of the switching power circuit with overheat protector that this utility model is provided
Structural representation.
On the basis of above-mentioned first or second embodiment, it is preferable that the temperature sampling unit 31 also include by
3rd resistor R3 and critesistor RTThe series arm of composition；The first end of the series arm is the temperature sampling unit 31
Feeder ear VCC, 3rd resistor R3 and critesistor R in the series armTCommon node be the temperature sampling unit
31 electrical signal, the second end of the series arm are the earth terminal of the temperature sampling unit 31.
It should be noted that in the present embodiment, from critesistor RTAs temperature-sensing element, critesistor RTTypical case
Feature is temperature sensitive, shows different resistance values at different temperature.Critesistor RTIncluding two classes, a class is just
Temperature coefficient thermistor, its resistance value are raised with temperature and are increased；Another kind of is negative tempperature coefficient thermistor, its resistance value
Raise with temperature and reduce.
Further, the first end of 3rd resistor R3 is the first end of the series arm, 3rd resistor R3
The second end connect the critesistor RTFirst end, the critesistor RTThe second end be the second of the series arm
End.
In the present embodiment, critesistor RTThe voltage at two ends is the total electricity in first resistor R1 and second resistance R2
Pressure, and the voltage at first resistor R1 two ends is equal to the voltage difference between the base stage of audion 32 and emitter stage.Therefore, first
On the premise of the resistance of resistance R1 and second resistance R2 is constant, if critesistor RTThe voltage at two ends reduces, then first resistor R1
The voltage at two ends reduces, and the voltage difference between the base stage of audion 32 and emitter stage reduces；If critesistor RTThe voltage at two ends
Increase, then the voltage increase at first resistor R1 two ends, the voltage difference increase between the base stage of audion 32 and emitter stage.
In one preferred embodiment, the critesistor RTFor semistor, and three pole
Pipe 32 is NPN triode.
It should be noted that in the present embodiment, from semistor, and connected according to foregoing circuit
Relation, can learn when ambient temperature is raised, critesistor RTResistance increase, critesistor RTThe voltage increase at two ends, first
The voltage correspondence at resistance R1 two ends increases, i.e., the voltage difference correspondence between the base stage of NPN triode and emitter stage increases, and works as voltage
When difference is more than the emitter junction conducting voltage of NPN triode, NPN triode is accordingly turned on.
Another preferred embodiment in, the critesistor RTFor negative tempperature coefficient thermistor, and described three
Pole pipe 32 is NPN triode.
It should be noted that in the present embodiment, from negative tempperature coefficient thermistor, and connected according to foregoing circuit
Relation, can learn when ambient temperature is raised, critesistor RTResistance reduce, critesistor RTThe voltage at two ends reduces, and first
The voltage correspondence at resistance R1 two ends reduces, i.e., the voltage difference correspondence between the base stage of NPN triode and emitter stage reduces, and works as voltage
When difference is less than the emitter junction conducting voltage of NPN triode, NPN triode is accordingly turned on.
Fig. 4 is referred to, is the 4th embodiment of the switching power circuit with overheat protector that this utility model is provided
Structural representation.
The present embodiment with the difference of above-mentioned 3rd embodiment is, in the switch with overheat protector that the present embodiment is provided
In power circuit, the critesistor RTFirst end be the series arm first end, the critesistor RTThe second end
Connect the first end of 3rd resistor R3, the second end of 3rd resistor R3 is the second end of the series arm.
It should be noted that compared to second embodiment, this enforcement is by 3rd resistor R3 and critesistor RTPosition
Exchange, therefore, in the present embodiment, the voltage at 3rd resistor R3 two ends is the total electricity in first resistor R1 and second resistance R2
Press, the voltage at first resistor R1 two ends is equal to the voltage difference between the base stage of audion 32 and emitter stage in the same manner.Further, first
On the premise of the resistance of resistance R1 and second resistance R2 is constant, if the voltage at 3rd resistor R3 two ends reduces, first resistor R1
The voltage at two ends reduces, and the voltage difference between the base stage of audion 32 and emitter stage reduces；If the voltage at 3rd resistor R3 two ends
Increase, then the voltage increase at first resistor R1 two ends, the voltage difference increase between the base stage of audion 32 and emitter stage.
In one preferred embodiment, the critesistor RTFor negative tempperature coefficient thermistor, and three pole
Pipe 32 is NPN triode.
It should be noted that in the present embodiment, from negative tempperature coefficient thermistor, and connected according to foregoing circuit
Relation, when can learn that ambient temperature is raised, critesistor RTResistance reduce, critesistor RTThe voltage at two ends reduces, and the 3rd is electric
The voltage increase at resistance R3 two ends, the voltage correspondence at first resistor R1 two ends increase, i.e., between the base stage of NPN triode and emitter stage
Voltage difference correspondence increase, when voltage difference more than NPN triode emitter junction conducting voltage when, NPN triode is accordingly turned on.
Another preferred embodiment in, the critesistor RTFor semistor, and described three
Pole pipe 32 is NPN triode.
It should be noted that in the present embodiment, from semistor, and connected according to foregoing circuit
Relation, can learn when ambient temperature is raised, critesistor RTResistance increase, critesistor RTThe voltage increase at two ends, the 3rd
The voltage at resistance R3 two ends reduces, and the voltage correspondence at first resistor R1 two ends reduces, i.e., the base stage of NPN triode and emitter stage it
Between voltage difference correspondence reduce, when voltage difference less than NPN triode emitter junction conducting voltage when, NPN triode is accordingly turned on.
Fig. 5 is referred to, is the 5th embodiment of the switching power circuit with overheat protector that this utility model is provided
Structural representation.
On the basis of above-mentioned second embodiment, it is preferable that the temperature sampling unit 31 also includes 3rd resistor R3
With integrated temperature sensor L1；Integrated temperature sensor L1 has positive power source terminal, electrical signal and negative power end；Institute
The first end for stating 3rd resistor R3 is the feeder ear V of the temperature sampling unit 31CC, the second end connection of 3rd resistor R3
The positive power source terminal of integrated temperature sensor L1；The electrical signal of integrated temperature sensor L1 is adopted for the temperature
The electrical signal of sample unit 31, the negative power end are the earth terminal of the temperature sampling unit 31.
It should be noted that in the present embodiment, from integrated temperature sensor L1 as temperature-sensing element, so-called integrated temperature
Degree sensor L1 is just referred to and is integrated with temperature sensor, signal amplification circuit, temperature-compensation circuit, reference power circuit 10 etc.
In interior less semiconductor chip.Its typical feature is temperature sensitive, and exports different electricity at different temperature
Signal.Electrical signal types according to output are divided, and it is two classes that integrated temperature sensor L1 is divided to, and a class is current mode, and which is in difference
At a temperature of export different voltage signals；Another kind of is current mode, and which exports different current signals at different temperature.
Integrated temperature sensor L1 and traditional critesistor RTCompare, with the linearity it is good, sensitivity is high, output signal
Greatly, and standardizing standard advantage.
Further, integrated temperature sensor L1 is positive temperature coefficient temperature sensor, and the audion 32 is
NPN triode.
It should be noted that voltage-type integrated temperature sensor L1 of this enforcement from positive temperature coefficient, and according to above-mentioned
Circuit connecting relation, can learn when ambient temperature is raised, the voltage increase of integrated temperature sensor L1 output, first resistor R1
The voltage correspondence at two ends increases, i.e., the voltage difference correspondence between the base stage of NPN triode and emitter stage increases, when voltage difference is more than
During the emitter junction conducting voltage of NPN triode, NPN triode is accordingly turned on.
The switching power circuit with overheat protector that this utility model embodiment is provided, arranges thermal-shutdown circuit, including
Temperature sampling unit and audion, wherein, the base stage of the electrical signal connecting triode of temperature sampling unit, audion
Grounded emitter, colelctor electrode connect the reference edge of constant-current control circuit；And by the voltage output end connection constant current of power circuit
The input of control circuit, the outfan connection load incoming end of constant-current control circuit, can be in variation of ambient temperature, by mistake
The input voltage of the reference edge of the colelctor electrode control constant-current control circuit of the audion in warm protection circuit, and then according to current temperature
Degree adaptively regulates and controls to the output of Switching Power Supply so that what constant-current control circuit was connect is supported on temperature change mistake
The running parameter holding work matched with Current Temperatures with one in journey, meanwhile, also so that the internal temperature of Switching Power Supply and
Ambient temperature reaches a thermal balance, can be effectively reduced power supply itself and load because of excess temperature impaired probability, and carry
High Consumer's Experience.
The above is preferred implementation of the present utility model, it is noted that for the ordinary skill of the art
For personnel, on the premise of without departing from this utility model principle, some improvement and deformation can also be made, these improve and become
Shape is also considered as protection domain of the present utility model.
Claims (11)
1. a kind of switching power circuit with overheat protector, it is characterised in that including power input, load incoming end, power supply
Circuit, constant-current control circuit and thermal-shutdown circuit；
The power circuit has voltage input end and voltage output end；The constant-current control circuit has input, outfan
And reference edge；
The power input connects the voltage input end of the power circuit；The voltage output end connection institute of the power circuit
State the input of constant-current control circuit；The outfan of the constant-current control circuit connects the load incoming end；
The thermal-shutdown circuit includes temperature sampling unit and audion；The temperature sampling unit has electric signal output
End, earth terminal and the feeder ear for accessing DC power signal；The electrical signal connects the base stage of the audion；
The grounded emitter of the audion, the colelctor electrode of the audion connect the reference edge of the constant-current control circuit.
2. the switching power circuit with overheat protector as claimed in claim 1, it is characterised in that the thermal-shutdown circuit is also
Including first resistor and second resistance；
The first resistor is connected across between the base stage of the audion and emitter stage；Also,
The electrical signal of the temperature sampling unit connects the base stage of the audion, specially：
The electrical signal of the temperature sampling unit connects the base stage of the audion by the second resistance.
3. the switching power circuit with overheat protector as any one of claim 1 or 2, it is characterised in that the temperature
Degree sampling unit also includes the series arm being made up of 3rd resistor and critesistor；
The first end of the series arm is the feeder ear of the temperature sampling unit, the 3rd resistor in the series arm and
The common node of critesistor is the electrical signal of the temperature sampling unit, and the second end of the series arm is described
The earth terminal of temperature sampling unit.
4. the switching power circuit with overheat protector as claimed in claim 3, it is characterised in that the first of the 3rd resistor
The first end for the series arm, the second end of the 3rd resistor is held to connect the first end of the critesistor, the heat
Second end of quick resistance is the second end of the series arm.
5. the switching power circuit with overheat protector as claimed in claim 4, it is characterised in that the critesistor is positive temperature
Degree coefficient resistance, and the audion is NPN triode.
6. the switching power circuit with overheat protector as claimed in claim 4, it is characterised in that the critesistor is subzero temperature
Degree coefficient resistance, and the audion is PNP triode.
7. the switching power circuit with overheat protector as claimed in claim 3, it is characterised in that the first of the critesistor
Hold the first end for the series arm, the second end of the critesistor connects the first end of the 3rd resistor, described the
Second end of three resistance is the second end of the series arm.
8. the switching power circuit with overheat protector as claimed in claim 7, it is characterised in that the critesistor is subzero temperature
Degree coefficient resistance, and the audion is NPN triode.
9. the switching power circuit with overheat protector as claimed in claim 7, it is characterised in that the critesistor is positive temperature
Degree coefficient resistance, and the audion is PNP triode.
10. the switching power circuit with overheat protector as any one of claim 1 or 2, it is characterised in that the temperature
Degree sampling unit also includes 3rd resistor and integrated temperature sensor；The integrated temperature sensor has positive power source terminal, telecommunications
Number outfan and negative power end；
The first end of the 3rd resistor is the feeder ear of the temperature sampling unit, and the second end of the 3rd resistor connects institute
State the positive power source terminal of integrated temperature sensor；The electrical signal of the integrated temperature sensor is the temperature sampling unit
Electrical signal, the negative power end is the earth terminal of the temperature sampling unit.
11. switching power circuits with overheat protector as claimed in claim 10, it is characterised in that the integrated temperature sensing
Device is positive temperature coefficient temperature sensor, and the audion is NPN triode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621050842.9U CN206041465U (en) | 2016-09-12 | 2016-09-12 | Switching power supply circuit with over-temperature protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621050842.9U CN206041465U (en) | 2016-09-12 | 2016-09-12 | Switching power supply circuit with over-temperature protection |
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| Publication Number | Publication Date |
|---|---|
| CN206041465U true CN206041465U (en) | 2017-03-22 |
Family
ID=58299908
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201621050842.9U Active CN206041465U (en) | 2016-09-12 | 2016-09-12 | Switching power supply circuit with over-temperature protection |
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| CN109510480A (en) * | 2018-12-27 | 2019-03-22 | 李清明 | Low-voltage lighting system |
| CN111749903B (en) * | 2019-03-28 | 2022-06-24 | 杭州三花研究院有限公司 | Control method, control system, and electric pump |
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| C14 | Grant of patent or utility model | ||
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