CN103579995B - Direct-current input switching power source and undervoltage protection circuit thereof - Google Patents
Direct-current input switching power source and undervoltage protection circuit thereof Download PDFInfo
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- CN103579995B CN103579995B CN201210271310.8A CN201210271310A CN103579995B CN 103579995 B CN103579995 B CN 103579995B CN 201210271310 A CN201210271310 A CN 201210271310A CN 103579995 B CN103579995 B CN 103579995B
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Abstract
The invention discloses a direct-current input switching power source and an undervoltage protection circuit of the direct-current input switching power source. The undervoltage protection circuit of the direct-current input switching power source comprises a detection module, a control module and a return difference module, wherein the detection module is used for detecting the input voltage of the direct-current power source, the control module is used for controlling a PWM chip to stop working when the detected input voltage is lower than the protection point voltage, the return difference module is used for playing a role in difference return, the detection module comprises a three-end adjustable shunt reference voltage source and at least two divider resistors, the divider resistors are connected between the direct-current power source and the ground in series, the input end of the three-end adjustable shunt reference voltage source is connected with a corresponding connecting point between every two adjacent divider resistors, an anode of the three-end adjustable shunt reference voltage source is grounded, a cathode of the three-end adjustable shunt reference voltage source is connected with the control module, and the return difference module is connected with the corresponding connecting point between every two adjacent divider resistors. According to the technical scheme, accuracy of an undervoltage protection point and accuracy of the return difference are improved, and thus the undervoltage protection circuit of the direct-current input switching power source can be wider in application range.
Description
Technical field
The present invention relates to power protection, more particularly, to a kind of direct current input switch power supply and its under-voltage protecting circuit.
Background technology
In direct current input switch power supply, generally adopt under-voltage protecting circuit, when the input voltage vin of DC source is too low
When, drag down the voltage of the feedback compensation terminal Vcomp of PWM chip, to seal and stop the output of PWM chip, so that this PWM chip is driven
Dynamic metal-oxide-semiconductor cut-off, plays the effect of under-voltage protection like this.
Traditional under-voltage protecting circuit as shown in Figure 1, this circuit can realize under-voltage protection function, but under-voltage protection point
And the precision of return difference is all very poor.It is specially：
Work as input voltage vin>Vup（The upper limit of under-voltage protection point）When, stabilivolt VZ1 turns on, and audion Q1 turns on, institute
So that the collector voltage of audion Q1 is pulled low so that audion Q2 cut-off, and the feedback compensation terminal Vcomp of PWM chip is high electricity
Flat, therefore, PWM chip can be with normal work.However, working as input voltage vin<Vdown1（The lower limit of designed under-voltage protection point）
When, understand some because of the leakage current of stabilivolt VZ1 and flow through audion Q1, audion Q1 can be made to continue conducting, so that PWM
Chip remains to be continually maintained in working condition, and therefore, actual under-voltage protection point lower limit Vdown can protect than designed pressure
The lower limit Vdown1 of point is lower.It is additionally, since the size of the leakage current of stabilivolt VZ1 and three poles of the same model of same producer
The size of pipe Q1 conducting electric current suffers from certain device discreteness, and it is very accurate that occurrence can not be accomplished, therefore, this circuit
Under-voltage protection point also will produce corresponding diversity, so, the precision of under-voltage protection point is all very poor.
In addition, as shown in figure 1, resistance R4 plays return difference effect, ideally：When input voltage vin is from less than under-voltage guarantor
When the lower limit Vdown of shield point is gradually increased to upper limit Vup less than under-voltage protection point, flow through the electric current of resistance R1, part stream
Cross stabilivolt VZ1 and resistance R2, another part flows through resistance R4 and audion Q2 so that the voltage at resistance R2 two ends is consistently lower than
The cut-in voltage of audion Q1, and then make the feedback compensation terminal Vcomp of PWM chip be in low level all the time.But due to steady
It is very accurate that the occurrence of the leakage current of pressure pipe VZ1 and audion Q1 conducting electric current can not be accomplished, therefore, the return difference of this circuit
Precision is also very poor.
When the required precision of under-voltage protection point and return difference is higher, this under-voltage protecting circuit has just shown office
Sex-limited, no longer completely applicable.
Content of the invention
The technical problem to be solved in the present invention is, the above-mentioned under-voltage protection point for prior art and the precision of return difference are equal
Very poor defect, provides a kind of under-voltage protecting circuit, and the precision of its under-voltage protection point and return difference is all very high.
The technical solution adopted for the present invention to solve the technical problems is：Construct a kind of under-voltage protecting circuit, be connected to PWM
Chip and DC source, described under-voltage protecting circuit includes：
For detecting the detection module of the input voltage of DC source；
For when the input voltage being detected is less than protection point voltage, controlling the out-of-work control module of PWM chip；
And
It is connected between described detection module and described control module, and be used for the return difference module of return difference effect；Wherein,
Described detection module includes three end adjustable shunt reference voltage sources and at least two divider resistances, and described at least two
Individual divider resistance is connected between DC source and ground, and the input of described three end adjustable shunt reference voltage sources connects accordingly
The junction point of two adjacent divider resistances, the plus earth of described three end adjustable shunt reference voltage sources, described three end adjustable shunts
The negative electrode of reference voltage source connects described control module, and, described return difference module connects corresponding two adjacent divider resistances
Junction point.
In under-voltage protecting circuit of the present invention, described control module includes first resistor group, second resistance group, steady
Pressure pipe and switching tube, wherein, the first end of described first resistor group connects DC source, and the negative electrode of described stabilivolt connects described the
Second end of one resistance group and the negative electrode of described three end adjustable shunt reference voltage sources, the anode of described stabilivolt connects described the
The first end of two resistance groups, the second end ground connection of described second resistance group, the control end of described switching tube connects described stabilivolt
Anode, the first end of described switching tube is the outfan of described control module, described switching tube second end ground connection.
In under-voltage protecting circuit of the present invention, described under-voltage protecting circuit also includes the second diode, described time
Difference module includes return difference resistance and the first diode, and wherein, the anode of described second diode connects the feedback of described PWM chip
Compensate end, the negative electrode of described second diode connects the first end of described switching tube and the negative electrode of described first diode, described
The anode of the first diode connects the first end of described return difference resistance, and the second end of described return difference resistance connects corresponding two partial pressures
The junction point of resistance.
In under-voltage protecting circuit of the present invention, described under-voltage protecting circuit also includes the second diode, described time
Difference module includes return difference resistance, and wherein, the anode of described second diode connects the feedback compensation terminal of described PWM chip, described
The negative electrode of the second diode connects the first end of described switching tube and the first end of described return difference resistance, and the of described return difference resistance
Two ends connect the corresponding junction point of at least two divider resistances.
In under-voltage protecting circuit of the present invention, in PWM chip normal work, the second end of described return difference resistance
Locate to the voltage on ground to be more than the voltage of the feedback compensation terminal of PWM chip to ground.
In under-voltage protecting circuit of the present invention, described return difference module includes return difference resistance and the first diode, its
In, the negative electrode of described first diode connects the first end of described switching tube and the feedback compensation terminal of described PWM chip, and described the
The anode of one diode connects the first end of described return difference resistance, and the second end of described return difference resistance connects at least two divider resistances
Corresponding junction point.
In under-voltage protecting circuit of the present invention, in PWM chip normal work, the second end of described return difference resistance
Locate to the voltage on ground to be less than the voltage of the feedback compensation terminal of PWM chip to ground.
In under-voltage protecting circuit of the present invention, described return difference module includes return difference resistance and the first diode, its
In, the anode of described first diode connects the first end of described switching tube and the feedback compensation terminal of described PWM chip, and described the
The negative electrode of one diode connects the first end of described return difference resistance, and the second end of described return difference resistance connects at least two divider resistances
Corresponding junction point.
In under-voltage protecting circuit of the present invention, in PWM chip normal work, the second end of described return difference resistance
Locate to the voltage on ground to be less than the voltage of the feedback compensation terminal of PWM chip to ground.
In under-voltage protecting circuit of the present invention, described at least two divider resistances are the first divider resistance and second
Divider resistance, and the junction point of described first divider resistance and the second divider resistance connects described three end adjustable shunt benchmark respectively
The input of voltage source and the second end of return difference resistance.
In under-voltage protecting circuit of the present invention, described at least two divider resistances be the first divider resistance, second
Divider resistance, the 3rd divider resistance, and described DC source pass sequentially through described first divider resistance, the second divider resistance,
Three divider resistances connect ground, and the second end of described return difference resistance connects the connection of described first divider resistance and the second divider resistance
Point, the input of described three end adjustable shunt reference voltage sources connects the connection of described second divider resistance and the 3rd divider resistance
Point.
In under-voltage protecting circuit of the present invention, described at least two divider resistances be the first divider resistance, second
Divider resistance, the 3rd divider resistance, and described DC source pass sequentially through described first divider resistance, the second divider resistance,
Three divider resistances connect ground, and the input of described three end adjustable shunt reference voltage sources connects described first divider resistance and second
The junction point of divider resistance, the second end of described return difference resistance connects the connection of described second divider resistance and the 3rd divider resistance
Point.
The present invention also constructs a kind of direct current input switch power supply, is connected to DC source, described direct current input switch power supply
Including PWM chip, described direct current input switch power supply also includes above-described under-voltage protecting circuit.
Implement technical scheme, traditional due to be instead of with three end adjustable shunt reference voltage sources of high precision
Stabilivolt and audion, so improve the precision of under-voltage protection point and return difference, so that the application of this under-voltage protecting circuit
More extensive.
In addition, the electric current of return difference module in under-voltage protecting circuit can only one-way flow, further improve return difference essence
Degree.
Brief description
Below in conjunction with drawings and Examples, the invention will be further described, in accompanying drawing：
Fig. 1 is the circuit diagram of traditional under-voltage protecting circuit；
Fig. 2 is the logic chart of under-voltage protecting circuit embodiment one of the present invention；
Fig. 3 is the circuit diagram of under-voltage protecting circuit embodiment two of the present invention；
Fig. 4 is the circuit diagram of under-voltage protecting circuit embodiment three of the present invention；
Fig. 5 is the circuit diagram of under-voltage protecting circuit example IV of the present invention；
Fig. 6 is the circuit diagram of under-voltage protecting circuit embodiment five of the present invention.
Specific embodiment
As shown in Fig. 2 in the logic chart of under-voltage protecting circuit embodiment one of the present invention, this under-voltage protecting circuit is connected to
DC source and PWM chip, and include detection module 10, control module 20 and return difference module 30, wherein, detection module 10 is used for
The input voltage of detection DC source；Control module 20 is used for, when the input voltage being detected is less than protection point voltage, controlling
PWM chip quits work；Return difference module 30 is connected between detection module 10 and control module 20 and plays return difference effect.And,
Detection module 10 includes three end adjustable shunt reference voltage sources（Fig. 1 is not shown）With at least two divider resistances（Not shown）, and
This module at least needs two divider resistances to be connected between DC source and ground, the input of three end adjustable shunt reference voltage sources
End connects the junction point of corresponding two adjacent divider resistances, the plus earth of three end adjustable shunt reference voltage sources, and three ends are adjustable
The negative electrode link control module 20 of shunting reference voltage source, and, return difference module 30 connects corresponding two adjacent divider resistances
Junction point.Herein it should be noted that the input of return difference module 30 and three end adjustable shunt reference voltage sources can be connected in same
Point, also can be connected in different points, as long as can guarantee that return difference module 30 can play return difference and act on.
Fig. 3 is the circuit diagram of under-voltage protecting circuit embodiment two of the present invention, and this under-voltage protecting circuit includes detection module, control
Molding block, return difference module and diode D2, wherein, detection module includes resistance R1, resistance R2 and three end adjustable shunt benchmark electricity
Potential source U.Control module includes resistance R4, resistance R6, stabilivolt VZ1 and audion Q1.Return difference module includes resistance R5 and two poles
Pipe D1.And, resistance R1, resistance R2 are connected between DC source and ground, and the junction point of resistance R1 and resistance R2 connects three ends
The input of adjustable shunt reference voltage source U and second end of resistance R5, the anode of three end adjustable shunt reference voltage source U connects
Ground.The first end of resistance R4 connects DC source, and second end of resistance R4 connects negative electrode and the three end adjustable shunts of stabilivolt VZ1
The negative electrode of reference voltage source U, the first end of anode connecting resistance R6 of stabilivolt VZ1 and the base stage of audion Q1, the of resistance R6
Two end ground connection, the grounded emitter of audion Q1, the colelctor electrode of audion Q1 connects the negative electrode of diode D2 and the moon of diode D1
Pole, the anode of diode D2 connects the feedback compensation terminal Vcomp of PWM chip, the first end of the anode connecting resistance R5 of diode D1.Close
In the feedback compensation terminal Vcomp of PWM chip, it should be noted that, the feedback compensation terminal Vcomp of PWM chip is connected to PWM chip
Outfan, and in PWM chip normal work, that is, export the pwm signal of a certain dutycycle, the feedback compensation terminal of PWM chip
Vcomp is high level；When PWM chip quits work, that is, no pwm signal exports, and the feedback compensation terminal Vcomp of PWM chip is
Low level.And, the voltage of the feedback compensation terminal Vcomp of PWM chip can control the output of PWM chip, when the feedback of PWM chip
When compensating end Vcomp for high level, PWM chip normal work；When the feedback compensation terminal Vcomp of PWM chip is low level,
PWM chip quits work.
The operation principle of this under-voltage protecting circuit is described below：Explanation first, under-voltage protection point lower limit is Vdown,
The under-voltage protection point upper limit is Vup, and return difference is Vup-Vdown.In addition, resistance R1, resistance R2 can be chosen according to following standard
Resistance：When the input voltage vin of DC source is equal to under-voltage protection point upper limit Vup, the voltage of resistance R2 is just equal to three ends
The reference voltage of adjustable shunt reference voltage source U, for example, when three end adjustable shunt reference voltage source U select model AZ431, base
Quasi- voltage is 1.24V.When this under-voltage protecting circuit works, when the input voltage vin of DC source is more than on under-voltage protection point
During limit Vup, the voltage at resistance R2 two ends will exceed 1.24V, and the negative electrode of three end adjustable shunt reference voltage source U is low level,
It is about 1V, the conducting voltage of stabilivolt VZ1 is 5.1V, and therefore, stabilivolt VZ1 can not turn on, and audion Q1 is in cut-off shape
State, the feedback compensation terminal Vcomp of PWM chip is high level, and PWM chip can be with normal work；Input voltage when DC source
When Vin is less than under-voltage protection point lower limit Vdown, the voltage at resistance R2 two ends will be lower than 1.24V, three end adjustable shunt benchmark electricity
The negative electrode of potential source U is high level, now stabilivolt VZ1 ON operation, and the electric current part flowing through VZ1 flows through resistance R6, another
Part flows through audion Q1 so that audion Q1 is in saturation conduction state, and the feedback compensation terminal Vcomp of PWM chip is by three poles
Pipe Q1 clamped for low level, the output of PWM chip is sealed, and quits work.
The return difference module being made up of diode D1 and resistance R5, plays the effect of return difference in circuit.Work as input voltage
Vin when being gradually increased to less than under-voltage protection point upper limit Vup less than under-voltage protection point lower limit Vdown, due to just starting PWM core
The feedback compensation terminal Vcomp of piece by audion Q1 clamped for low level, flow through resistance R1 electric current some flow through resistance R5
With diode D1 composition branch road so that resistance R2 two ends voltage be less than 1.24V, three end adjustable shunt reference voltage source U's
Negative electrode is high level, and audion Q1 is constantly in saturation conduction state, and the feedback compensation terminal Vcomp of PWM chip always remains as
Low level, PWM chip does not work always；When input voltage vin is gradually lowered to be more than from upper limit Vup more than under-voltage protection point
During under-voltage protection point lower limit Vdown, the feedback compensation terminal Vcomp due to just starting PWM chip is high level, resistance R5 and two poles
The branch road of pipe D1 composition does not have electric current to flow through, and the voltage at resistance R2 two ends is higher than 1.24V, three end adjustable shunt reference voltage source U
Output be low level always, the feedback compensation terminal Vcomp of PWM chip is high level always, PWM chip normal work.
Fig. 4 is the circuit diagram of under-voltage protecting circuit embodiment three of the present invention, and this under-voltage protecting circuit includes detection module, control
Molding block, return difference module and diode D2, wherein, detection module includes resistance R1, resistance R2, resistance R3 and three end adjustable shunts
Reference voltage source U.Control module includes resistance R4, resistance R6, stabilivolt VZ1 and audion Q1.Return difference module includes resistance R5.
And, DC source passes sequentially through resistance R1, resistance R2, resistance R3 connect ground, the input of three end adjustable shunt reference voltage source U
End connects the junction point (B) of resistance R2 and resistance R3, the plus earth of three end adjustable shunt reference voltage source U.The of resistance R4
One end connection DC source, the negative electrode of the second end connection stabilivolt VZ1 of resistance R4 and three end adjustable shunt reference voltage source U's
Negative electrode, the first end of anode connecting resistance R6 of stabilivolt VZ1 and the base stage of audion Q1, the second end ground connection of resistance R6, three poles
The grounded emitter of pipe Q1, the colelctor electrode of audion Q1 connects the negative electrode of diode D2 and the first end of resistance R5, diode D2's
Anode connects the feedback compensation terminal Vcomp of PWM chip, and second end of resistance R5 connects the junction point (A) of resistance R1 and resistance R2.
The principle of the operation principle of the under-voltage protection shown in this embodiment and generation return difference is basic with the embodiment shown in Fig. 3
Identical, except that, due to eliminating diode D1, and, during PWM chip normal work（DC source is not owed
During pressure）, its feedback compensation terminal Vcomp output voltage may be above resistance R1, R2 junction point（A）The voltage at place, thus meeting
Electric current from left to right is produced on resistance R5.In addition, DC source occur under-voltage when, flow through resistance R5 electric current be from the right side to
Left.So, in different situations, the flow direction of its electric current is different for resistance R5, and the loss of this circuit so can be made to become big, thus
Make the deterioration in accuracy of return difference.In order to avoid this occurrence of, therefore, divider resistance is provided with three by this embodiment,
And connect second end of resistance R5 to resistance R1, the junction point of resistance R2, to ensure that the voltage at A point is consistently greater than
The voltage of the feedback compensation terminal Vcomp output of PWM chip, so that the electric current of resistance R5 can only flow to a left side from the right side, and can not
It flow to the right side from a left side.Certainly, in other embodiments, arrive at resistance R5 second end in PWM chip normal work as long as can guarantee that
The voltage on ground is more than the voltage of the feedback compensation terminal Vcomp of PWM chip, and resistance R5 second end may also connect to resistance R2, resistance
At the junction point of R3, or, when divider resistance is other quantity, resistance R5 second end is connected to other suitable two adjacent electricity
At the junction point of resistance.
Fig. 5 is the circuit diagram of under-voltage protecting circuit example IV of the present invention, and this under-voltage protecting circuit includes detection module, control
Molding block, return difference module, wherein, detection module includes resistance R1, resistance R2, resistance R3 and three end adjustable shunt reference voltage sources
U.Control module includes resistance R4, resistance R6, stabilivolt VZ1 and audion Q1.Return difference module includes resistance R5 and diode D1.
And, DC source passes sequentially through resistance R1, resistance R2, resistance R3 connect ground, the input of three end adjustable shunt reference voltage source U
End connects the junction point of resistance R1 and resistance R2（A）, the plus earth of three end adjustable shunt reference voltage source U.The of resistance R4
One end connection DC source, the negative electrode of the second end connection stabilivolt VZ1 of resistance R4 and three end adjustable shunt reference voltage source U's
Negative electrode, the first end of anode connecting resistance R6 of stabilivolt VZ1 and the base stage of audion Q1, the second end ground connection of resistance R6, three poles
The grounded emitter of pipe Q1, the colelctor electrode of audion Q1 meets the negative electrode of diode D1 and the feedback compensation terminal Vcomp of PWM chip,
The anode of the first terminating diode D1 of resistance R5, second end of resistance R5 connects the junction point of resistance R2 and resistance R3（B）.
The principle of the operation principle of the under-voltage protection shown in this embodiment and generation return difference is basic with the embodiment shown in Fig. 3
Identical, except that, due to eliminating diode D2, and, during PWM chip normal work（DC source is not owed
During pressure）, although its feedback compensation terminal Vcomp output is high level, and the voltage of its feedback compensation terminal Vcomp output is possible to
The second end less than resistance R5（B）Locate the voltage to ground, so can produce dextrosinistral electric current on resistance R5, so that
The voltage of the feedback compensation terminal Vcomp of PWM chip is affected.This for avoiding the occurrence of, so, this embodiment point
Piezoresistance is provided with three, and second end of resistance R5 is connected to the junction point of resistance R2, resistance R3（B）Place, to ensure B
At point, the voltage to ground is consistently less than the voltage that the feedback compensation terminal Vcomp of PWM chip exports.Certainly, in other embodiments,
As long as can guarantee that the voltage arriving ground at resistance R5 second end in PWM chip normal work is less than the feedback compensation terminal of PWM chip
Voltage, resistance R5 second end may also connect to resistance R1, at the junction point of resistance R2, or, be other numbers in divider resistance
During amount, resistance R5 second end is connected at the junction point of other suitable two adjacent resistors.
Fig. 6 is the circuit diagram of under-voltage protecting circuit embodiment five of the present invention, and this under-voltage protecting circuit includes detection module, control
Molding block, return difference module, wherein, detection module includes resistance R1, resistance R2, resistance R3 and three end adjustable shunt reference voltage sources
U.Control module includes resistance R4, resistance R6, stabilivolt VZ1 and audion Q1.Return difference module includes resistance R5 and diode D1.
And, DC source passes sequentially through resistance R1, resistance R2, resistance R3 connect ground, the input of three end adjustable shunt reference voltage source U
End connects the junction point of resistance R1 and resistance R2（A）, the plus earth of three end adjustable shunt reference voltage source U.The of resistance R4
One end connection DC source, the negative electrode of the second end connection stabilivolt VZ1 of resistance R4 and three end adjustable shunt reference voltage source U's
Negative electrode, the first end of anode connecting resistance R6 of stabilivolt VZ1 and the base stage of audion Q1, the second end ground connection of resistance R6, three poles
The grounded emitter of pipe Q1, the colelctor electrode of audion Q1 meets the anode of diode D1 and the feedback compensation terminal Vcomp of PWM chip,
The negative electrode of the first terminating diode D1 of resistance R5, second end of resistance R5 connects the junction point of resistance R2 and resistance R3（B）.
The operation principle of the under-voltage protection of the operation principle of the under-voltage protection shown in this embodiment and the embodiment shown in Fig. 3
Compare, be not both the principle of return difference generation, specific as follows：When input voltage vin from less than under-voltage protection point lower limit Vdown by
When being gradually increased to less than under-voltage protection point upper limit Vup, the feedback compensation terminal Vcomp of PWM chip by audion Q1 clamped for low electricity
Flat, PWM chip quits work；When input voltage vin is from being gradually lowered to more than under-voltage protection more than under-voltage protection point upper limit Vup
During point lower limit Vdown, the feedback compensation terminal Vcomp due to just starting PWM chip is high level, flows through resistance R5 and diode D1
Electric current certain voltage is produced on resistance R3 so that voltage on resistance R2 and resistance R3 raises, at A point, arrive ground
Voltage raises, and produces return difference, and the feedback compensation terminal Vcomp making PWM chip is high level always, PWM chip normal work.Separately
Outward, it should be noted that, for ensure resistance R5 and diode D1 composition return difference module can play return difference effect, it is necessary to assure resistance
Second end of R5 to ground voltage be less than PWM chip feedback compensation terminal Vcomp voltage.Certainly, an above simply enforcement
Example, as long as can guarantee that the voltage arriving ground at second end of resistance R5 is less than the voltage of the feedback compensation terminal Vcomp of PWM chip, electricity
Second end of resistance R5 is also attached to resistance R1, at the junction point of resistance R2, or, when divider resistance has other quantity, electricity
Second end of resistance R5 is also attached at the junction point of other suitable two adjacent divider resistances.
The present invention also constructs a kind of direct current input switch power supply, and this direct current input switch power supply is used for defeated to DC source
Enter voltage and enter line translation, and this direct current input switch power supply includes the under-voltage protection described in PWM chip and any of the above embodiment
Circuit.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for the skill of this area
For art personnel, the present invention can have various modifications and variations.For example, resistance R4, resistance R6 can respectively by first resistor group,
Two resistance groups are replacing, and first resistor group and second resistance group can be respectively by the resistance groups of multiple series, parallel or mixing connection
Become.In addition, audion Q1 also can be selected for other switching tubes, for example low power metal-oxide-semiconductor etc..All in the spirit and principles in the present invention
Within, any modification, equivalent substitution and improvement made etc., should be included within scope of the presently claimed invention.
Claims (12)
1. a kind of under-voltage protecting circuit, is connected to PWM chip and DC source it is characterised in that described under-voltage protecting circuit bag
Include：
For detecting the detection module of the input voltage of DC source；
For when the input voltage being detected is less than protection point voltage, controlling the out-of-work control module of PWM chip；Described
Control module includes first resistor group, second resistance group, stabilivolt and switching tube, wherein, the first end of described first resistor group
Connect DC source, the negative electrode of described stabilivolt connects the second end and the three end adjustable shunt reference voltage sources of described first resistor group
Negative electrode, the anode of described stabilivolt connects the first end of described second resistance group, the second end ground connection of described second resistance group,
The control end of described switching tube connects the anode of described stabilivolt, and the first end of described switching tube is the output of described control module
End, the second end ground connection of described switching tube；And
It is connected between described detection module and described control module, and be used for the return difference module of return difference effect；Wherein,
Described detection module includes described three end adjustable shunt reference voltage sources and at least two divider resistances, and described at least two
Individual divider resistance is connected between DC source and ground, and the input of described three end adjustable shunt reference voltage sources connects accordingly
The junction point of two adjacent divider resistances, the plus earth of described three end adjustable shunt reference voltage sources, described three end adjustable shunts
The negative electrode of reference voltage source connects described control module, and, described return difference module connects corresponding two adjacent divider resistances
Junction point.
2. under-voltage protecting circuit according to claim 1 is it is characterised in that described under-voltage protecting circuit also includes the two or two
Pole pipe, described return difference module includes return difference resistance and the first diode, and wherein, the anode connection of described second diode is described
The feedback compensation terminal of PWM chip, the negative electrode of described second diode connects the first end of described switching tube and described one or two pole
The negative electrode of pipe, the anode of described first diode connects the first end of described return difference resistance, and the second end of described return difference resistance is even
Connect the junction point of corresponding two divider resistances.
3. under-voltage protecting circuit according to claim 1 is it is characterised in that described under-voltage protecting circuit also includes the two or two
Pole pipe, described return difference module includes return difference resistance, and wherein, the anode of described second diode connects the feedback of described PWM chip
Compensate end, the negative electrode of described second diode connects the first end of described switching tube and the first end of described return difference resistance, described
Second end of return difference resistance connects the corresponding junction point of at least two divider resistances.
4. under-voltage protecting circuit according to claim 3 is it is characterised in that in PWM chip normal work, described return difference
The voltage arriving ground at second end of resistance is more than the voltage of the feedback compensation terminal of PWM chip to ground.
5. under-voltage protecting circuit according to claim 1 is it is characterised in that described return difference module includes return difference resistance and
One diode, wherein, the negative electrode of described first diode connects the first end of described switching tube and the feedback benefit of described PWM chip
Repay end, the anode of described first diode connects the first end of described return difference resistance, the second end of described return difference resistance connect to
The corresponding junction point of few two divider resistances.
6. under-voltage protecting circuit according to claim 5 is it is characterised in that in PWM chip normal work, described return difference
The voltage arriving ground at second end of resistance is less than the voltage of the feedback compensation terminal of PWM chip to ground.
7. under-voltage protecting circuit according to claim 1 is it is characterised in that described return difference module includes return difference resistance and
One diode, wherein, the anode of described first diode connects the first end of described switching tube and the feedback benefit of described PWM chip
Repay end, the negative electrode of described first diode connects the first end of described return difference resistance, the second end of described return difference resistance connect to
The corresponding junction point of few two divider resistances.
8. under-voltage protecting circuit according to claim 7 is it is characterised in that in PWM chip normal work, described return difference
The voltage arriving ground at second end of resistance is less than the voltage of the feedback compensation terminal of PWM chip to ground.
9. under-voltage protecting circuit according to claim 2 is it is characterised in that described at least two divider resistances are first point
Piezoresistance and the second divider resistance, and the junction point of described first divider resistance and the second divider resistance connects described three ends respectively
The input of adjustable shunt reference voltage source and the second end of return difference resistance.
10. the under-voltage protecting circuit according to claim 3 or 4 is it is characterised in that described at least two divider resistances are the
One divider resistance, the second divider resistance, the 3rd divider resistance, and described DC source pass sequentially through described first divider resistance,
Second divider resistance, the 3rd divider resistance connect ground, and the second end of described return difference resistance connects described first divider resistance and the
The junction point of two divider resistances, the input of described three end adjustable shunt reference voltage sources connects described second divider resistance and the
The junction point of three divider resistances.
11. under-voltage protecting circuits according to any one of claim 5 to 8 are it is characterised in that described at least two partial pressures are electric
Hinder and pass sequentially through described first partial pressure for the first divider resistance, the second divider resistance, the 3rd divider resistance, and described DC source
Resistance, the second divider resistance, the 3rd divider resistance connect ground, and the input of described three end adjustable shunt reference voltage sources connects institute
State the first divider resistance and the junction point of the second divider resistance, the second end of described return difference resistance connects described second divider resistance
Junction point with the 3rd divider resistance.
A kind of 12. direct current input switch power supplys, are connected to DC source, and described direct current input switch power supply includes PWM chip, its
It is characterised by, described direct current input switch power supply also includes the under-voltage protecting circuit described in claim 1-8.
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| CN201210271310.8A CN103579995B (en) | 2012-08-01 | 2012-08-01 | Direct-current input switching power source and undervoltage protection circuit thereof |
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| CN201210271310.8A CN103579995B (en) | 2012-08-01 | 2012-08-01 | Direct-current input switching power source and undervoltage protection circuit thereof |
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| CN103579995A CN103579995A (en) | 2014-02-12 |
| CN103579995B true CN103579995B (en) | 2017-02-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109245052B (en) * | 2018-08-29 | 2024-04-12 | 广州金升阳科技有限公司 | Short-circuit protection circuit and switching power supply comprising same |
| CN109873398A (en) * | 2019-02-21 | 2019-06-11 | 广州视源电子科技股份有限公司 | Chip under-voltage protecting circuit and chip circuit |
| CN110837287B (en) * | 2019-10-17 | 2021-03-02 | 广州金升阳科技有限公司 | Restart circuit |
| CN116978904B (en) * | 2023-07-27 | 2024-02-23 | 屹晶微电子(台州)有限公司 | Power supply voltage stabilizing circuit and integrated chip |
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|---|---|---|---|---|
| CN1913272A (en) * | 2005-08-11 | 2007-02-14 | 艾默生网络能源系统有限公司 | Novel input undervoltage/overvoltage protection circuit |
| CN101436771A (en) * | 2007-11-16 | 2009-05-20 | 艾默生网络能源系统有限公司 | Power supply under-voltage protection circuit and power supply comprising same |
| CN201950344U (en) * | 2011-01-25 | 2011-08-31 | 深圳华意隆电气股份有限公司 | Voltage-type PWM half-bridge hard-switch inversion welding and cutting machine |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08191565A (en) * | 1995-01-05 | 1996-07-23 | Matsushita Electric Ind Co Ltd | Switching power supply |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1913272A (en) * | 2005-08-11 | 2007-02-14 | 艾默生网络能源系统有限公司 | Novel input undervoltage/overvoltage protection circuit |
| CN101436771A (en) * | 2007-11-16 | 2009-05-20 | 艾默生网络能源系统有限公司 | Power supply under-voltage protection circuit and power supply comprising same |
| CN201950344U (en) * | 2011-01-25 | 2011-08-31 | 深圳华意隆电气股份有限公司 | Voltage-type PWM half-bridge hard-switch inversion welding and cutting machine |
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| CN103579995A (en) | 2014-02-12 |
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