CN103579995A - 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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- CN103579995A CN103579995A CN201210271310.8A CN201210271310A CN103579995A CN 103579995 A CN103579995 A CN 103579995A CN 201210271310 A CN201210271310 A CN 201210271310A CN 103579995 A CN103579995 A CN 103579995A
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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, relate in particular to a kind of direct current input switch power supply and under-voltage protecting circuit thereof.
Background technology
In direct current input switch power supply; conventionally adopt under-voltage protecting circuit; when the input voltage vin of DC power supply is too low; drag down the voltage of the feedback compensation terminal Vcomp of PWM chip; to seal and stop the output of PWM chip; thereby make the metal-oxide-semiconductor cut-off of this PWM chip drives, play the effect of under-voltage protection like this.
Traditional under-voltage protecting circuit as shown in Figure 1, this circuit can be realized under-voltage protection function, but the precision of under-voltage protection point and return difference is all very poor.Be specially:
The upper limit when input voltage vin >Vup(under-voltage protection point) time; voltage-stabiliser tube VZ1 conducting; triode Q1 conducting; so; the collector voltage of triode Q1 is dragged down, and makes triode Q2 cut-off, and the feedback compensation terminal Vcomp of PWM chip is high level; therefore, PWM chip can work.Yet; lower limit when the designed under-voltage protection point of input voltage vin <Vdown1() time; because of the leakage current of voltage-stabiliser tube VZ1, understand some and flow through triode Q1; can make triode Q1 continue conducting; thereby make PWM chip still can continue to remain on operating state; therefore, actual under-voltage protection point lower limit Vdown can be lower than the lower limit Vdown1 of designed pressure protection point.And; because the size of leakage current and the size of triode Q1 On current of the voltage-stabiliser tube VZ1 of the same model of same producer has certain device discreteness; occurrence can not be accomplished very accurate; therefore; the under-voltage protection point of this circuit also will produce corresponding otherness; so the precision of under-voltage protection point is all very poor.
In addition; as shown in Figure 1; resistance R 4 plays return difference effect; ideally: when input voltage vin is elevated to from being less than the lower limit Vdown of under-voltage protection point the upper limit Vup that is less than under-voltage protection point gradually; flow through the electric current of resistance R 1, a part flows through voltage-stabiliser tube VZ1 and resistance R 2, and another part flows through resistance R 4 and triode Q2; the voltage that makes resistance R 2 two ends is all the time lower than the cut-in voltage of triode Q1, and then makes the feedback compensation terminal Vcomp of PWM chip all the time in low level.But due to the leakage current of voltage-stabiliser tube VZ1 and the occurrence of triode Q1 On current, can not accomplish very accurately, therefore, the precision of the return difference of this circuit 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 limitation, no longer completely applicable.
Summary of the invention
The technical problem to be solved in the present invention is, for the equal very poor defect of the above-mentioned under-voltage protection point of prior art and the precision of return difference, 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 in PWM chip and DC power supply, described under-voltage protecting circuit comprises:
Detection module for detection of the input voltage of DC power supply;
For during point voltage, controlling the out-of-work control module of PWM chip lower than protection at detected input voltage; And
Be connected between described detection module and described control module, and for playing the return difference module of return difference effect; Wherein,
Described detection module comprises three end adjustable shunt reference voltage sources and at least two divider resistances, and described at least two divider resistances are connected between DC power supply and ground, the input of described three end adjustable shunt reference voltage sources connects the tie point of corresponding two adjacent divider resistances, the plus earth of described three end adjustable shunt reference voltage sources, the negative electrode of described three end adjustable shunt reference voltage sources connects described control module, and described return difference module connects the tie point of corresponding two adjacent divider resistances.
In under-voltage protecting circuit of the present invention, described control module comprises the first resistor group, the second resistor group, voltage-stabiliser tube and switching tube, wherein, the first end of described the first resistor group connects DC power supply, the negative electrode of described voltage-stabiliser tube connects the second end of described the first resistor group and the negative electrode of described three end adjustable shunt reference voltage sources, the first end of the second resistor group described in the anodic bonding of described voltage-stabiliser tube, the second end ground connection of described the second resistor group, the control end of described switching tube connects the anode of described voltage-stabiliser tube, the first end of described switching tube is the output of described control module, the second end ground connection of described switching tube.
In under-voltage protecting circuit of the present invention; described under-voltage protecting circuit also comprises the second diode; described return difference module comprises return difference resistance and the first diode; wherein; the feedback compensation terminal of PWM chip described in the anodic bonding of described the second diode; the negative electrode of described the second diode connects the first end of described switching tube and the negative electrode of described the first diode; the first end of return difference resistance described in the anodic bonding of described the first diode, the second end of described return difference resistance connects the tie point of corresponding two divider resistances.
In under-voltage protecting circuit of the present invention; described under-voltage protecting circuit also comprises the second diode; described return difference module comprises return difference resistance; wherein; the feedback compensation terminal of PWM chip described in the anodic bonding of described the second diode; the negative electrode of described the second diode connects the first end of described switching tube and the first end of described return difference resistance, and the second end of described return difference resistance connects the corresponding tie point of at least two divider resistances.
In under-voltage protecting circuit of the present invention, when PWM chip works, the second end place of described return difference resistance is greater than the feedback compensation terminal of PWM chip to the voltage on ground to the voltage on ground.
In under-voltage protecting circuit of the present invention; described return difference module comprises return difference resistance and the first diode; wherein; the negative electrode of described the first diode connects the first end of described switching tube and the feedback compensation terminal of described PWM chip; the first end of return difference resistance described in the anodic bonding of described the first diode, the second end of described return difference resistance connects the corresponding tie point of at least two divider resistances.
In under-voltage protecting circuit of the present invention, when PWM chip works, the second end place of described return difference resistance is less than the feedback compensation terminal of PWM chip to the voltage on ground to the voltage on ground.
In under-voltage protecting circuit of the present invention; described return difference module comprises return difference resistance and the first diode; wherein; the feedback compensation terminal of the first end of switching tube and described PWM chip described in the anodic bonding of described the first diode; the negative electrode of described the first diode connects the first end of described return difference resistance, and the second end of described return difference resistance connects the corresponding tie point of at least two divider resistances.
In under-voltage protecting circuit of the present invention, when PWM chip works, the second end place of described return difference resistance is less than the feedback compensation terminal of PWM chip to the voltage on ground to the voltage on ground.
In under-voltage protecting circuit of the present invention; described at least two divider resistances are the first divider resistance and the second divider resistance, and the tie point of described the first divider resistance and the second divider resistance is connected respectively described three inputs of end adjustable shunt reference 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 are the first divider resistance, the second divider resistance, the 3rd divider resistance; and described DC power supply connects ground by described the first divider resistance, the second divider resistance, the 3rd divider resistance successively; the second end of described return difference resistance connects the tie point of described the first divider resistance and the second divider resistance, and the input of described three end adjustable shunt reference voltage sources connects the tie point of described the second divider resistance and the 3rd divider resistance.
In under-voltage protecting circuit of the present invention; described at least two divider resistances are the first divider resistance, the second divider resistance, the 3rd divider resistance; and described DC power supply connects ground by described the first divider resistance, the second divider resistance, the 3rd divider resistance successively; the input of described three end adjustable shunt reference voltage sources connects the tie point of described the first divider resistance and the second divider resistance, and the second end of described return difference resistance connects the tie point of described the second divider resistance and the 3rd divider resistance.
The present invention also constructs a kind of direct current input switch power supply, is connected in DC power supply, and described direct current input switch power supply comprises PWM chip, and described direct current input switch power supply also comprises above-described under-voltage protecting circuit.
Implement technical scheme of the present invention, owing to having replaced traditional voltage-stabiliser tube and triode with three high end adjustable shunt reference voltage sources of precision, thus improved the precision of under-voltage protection point and return difference, thus make the application of this under-voltage protecting circuit more extensive.
In addition, the electric current of the return difference module in under-voltage protecting circuit can only one-way flow, has further improved return difference precision.
Accompanying drawing explanation
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 diagram of under-voltage protecting circuit embodiment mono-of the present invention;
Fig. 3 is the circuit diagram of under-voltage protecting circuit embodiment bis-of the present invention;
Fig. 4 is the circuit diagram of under-voltage protecting circuit embodiment tri-of the present invention;
Fig. 5 is the circuit diagram of under-voltage protecting circuit embodiment tetra-of the present invention;
Fig. 6 is the circuit diagram of under-voltage protecting circuit embodiment five of the present invention.
Embodiment
As shown in Figure 2, in the logic diagram of under-voltage protecting circuit embodiment mono-of the present invention, this under-voltage protecting circuit is connected in DC power supply and PWM chip, and comprises detection module 10, control module 20 and return difference module 30, wherein, detection module 10 is for detection of the input voltage of DC power supply; Control module 20 during point voltage, is controlled PWM chip and is quit work lower than protection for the input voltage detected; Return difference module 30 is connected between detection module 10 and control module 20 and plays return difference effect.And, detection module 10 comprises three end adjustable shunt reference voltage sources (Fig. 1 is not shown) and at least two divider resistance (not shown), and this module at least needs two divider resistances to be connected between DC power supply and ground, the input of three end adjustable shunt reference voltage sources connects the tie point of corresponding two adjacent divider resistances, the plus earth of three end adjustable shunt reference voltage sources, the negative electrode link control module 20 of three end adjustable shunt reference voltage sources, and return difference module 30 connects the tie point of corresponding two adjacent divider resistances.The input that it should be noted that return difference module 30 and three end adjustable shunt reference voltage sources herein 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 effect.
Fig. 3 is the circuit diagram of under-voltage protecting circuit embodiment bis-of the present invention, and this under-voltage protecting circuit comprises detection module, control module, return difference module and diode D2, and wherein, detection module comprises resistance R 1, resistance R 2 and three end adjustable shunt reference voltage source U.Control module comprises resistance R 4, resistance R 6, voltage-stabiliser tube VZ1 and triode Q1.Return difference module comprises resistance R 5 and diode D1.And resistance R 1, resistance R 2 are connected between DC power supply and ground, the tie point of resistance R 1 and resistance R 2 is connected the input of three end adjustable shunt reference voltage source U and the second end of resistance R 5, the plus earth of three end adjustable shunt reference voltage source U.The first end of resistance R 4 connects DC power supply, the second end of resistance R 4 connects the negative electrode of voltage-stabiliser tube VZ1 and the negative electrode of three end adjustable shunt reference voltage source U, the first end of anode connecting resistance R6 of voltage-stabiliser tube VZ1 and the base stage of triode Q1, the second end ground connection of resistance R 6, the grounded emitter of triode Q1, the collector electrode of triode Q1 connects the negative electrode of diode D2 and the negative electrode of diode D1, the anode of diode D2 meets the feedback compensation terminal Vcomp of PWM chip, the first end of the anode connecting resistance R5 of diode D1.Feedback compensation terminal Vcomp about PWM chip, it should be noted that, the feedback compensation terminal Vcomp of PWM chip is connected in the output of PWM chip, and when PWM chip works, export the pwm signal of a certain duty ratio, the feedback compensation terminal Vcomp of PWM chip is high level; When PWM chip quits work,, without pwm signal output, the feedback compensation terminal Vcomp of PWM chip is low level.And the voltage of the feedback compensation terminal Vcomp of PWM chip can be controlled the output of PWM chip, when the feedback compensation terminal Vcomp of PWM chip is high level, the normal operation of PWM chip; When the feedback compensation terminal Vcomp of PWM chip is low level, PWM chip quits work.
The following describes the operation principle of this under-voltage protecting circuit: first explanation, under under-voltage protection point, be limited to Vdown, on under-voltage protection point, be limited to Vup, return difference is Vup-Vdown.In addition; can choose according to following standard the resistance of resistance R 1, resistance R 2: when the input voltage vin of DC power supply equals under-voltage protection point upper limit Vup; the voltage of resistance R 2 just equals the reference voltage of three end adjustable shunt reference voltage source U; for example; when three end adjustable shunt reference voltage source U select model AZ431, reference voltage is 1.24V.When this under-voltage protecting circuit work, when the input voltage vin of DC power supply is greater than under-voltage protection point upper limit Vup, the voltage at resistance R 2 two ends will surpass 1.24V, and the negative electrode of three end adjustable shunt reference voltage source U is low level, is approximately 1V, the conducting voltage of voltage-stabiliser tube VZ1 is 5.1V, therefore, voltage-stabiliser tube VZ1 can not conducting, and triode Q1 is in cut-off state, the feedback compensation terminal Vcomp of PWM chip is high level, and PWM chip can work; When the input voltage vin of DC power supply is less than under-voltage protection point lower limit Vdown; the voltage at resistance R 2 two ends will be lower than 1.24V; the negative electrode of three end adjustable shunt reference voltage source U is high level; now voltage-stabiliser tube VZ1 conducting work, an electric current part that flows through VZ1 flows through resistance R 6, and another part flows through triode Q1; make triode Q1 in saturation conduction state; the feedback compensation terminal Vcomp of PWM chip by triode Q1 clamped be low level, the output of PWM chip is sealed, and quits work.
The return difference module being comprised of diode D1 and resistance R 5 plays the effect of return difference in circuit.When input voltage vin is elevated to while being less than under-voltage protection point upper limit Vup gradually from being less than under-voltage protection point lower limit Vdown, due to the feedback compensation terminal Vcomp that just starts PWM chip by triode Q1 clamped be low level, flow through resistance R 1 electric current some flow through the branch road that resistance R 5 and diode D1 form, make the voltage at resistance R 2 two ends lower than 1.24V, the negative electrode of three end adjustable shunt reference voltage source U is high level, triode Q1 is always in saturation conduction state, the feedback compensation terminal Vcomp of PWM chip remains low level always, and PWM chip is not worked always; When input voltage vin is reduced to while being greater than under-voltage protection point lower limit Vdown gradually from being greater than the upper limit Vup of under-voltage protection point; owing to just starting the feedback compensation terminal Vcomp of PWM chip, it is high level; the branch road that resistance R 5 and diode D1 form does not have electric current to flow through; the voltage at resistance R 2 two ends is higher than 1.24V; the output of three end adjustable shunt reference voltage source U is low level always; the feedback compensation terminal Vcomp of PWM chip is high level always, the normal operation of PWM chip.
Fig. 4 is the circuit diagram of under-voltage protecting circuit embodiment tri-of the present invention; this under-voltage protecting circuit comprises detection module, control module, return difference module and diode D2; wherein, detection module comprises resistance R 1, resistance R 2, resistance R 3 and three end adjustable shunt reference voltage source U.Control module comprises resistance R 4, resistance R 6, voltage-stabiliser tube VZ1 and triode Q1.Return difference module comprises resistance R 5.And DC power supply connects ground, the three input contact resistance R2 of end adjustable shunt reference voltage source U and the tie point (B) of resistance R 3, the plus earth of three end adjustable shunt reference voltage source U by resistance R 1, resistance R 2, resistance R 3 successively.The first end of resistance R 4 connects DC power supply, the second end of resistance R 4 connects the negative electrode of voltage-stabiliser tube VZ1 and the negative electrode of three end adjustable shunt reference voltage source U, the first end of anode connecting resistance R6 of voltage-stabiliser tube VZ1 and the base stage of triode Q1, the second end ground connection of resistance R 6, the grounded emitter of triode Q1, the collector electrode of triode Q1 connects the negative electrode of diode D2 and the first end of resistance R 5, the feedback compensation terminal Vcomp of the anodic bonding PWM chip of diode D2, the second end contact resistance R1 of resistance R 5 and the tie point (A) of resistance R 2.
Principle and the embodiment shown in Fig. 3 of the operation principle of the under-voltage protection shown in this embodiment and generation return difference are basic identical; difference is; owing to having saved diode D1; and; PWM chip when normal operation when under-voltage (DC power supply do not occur); the voltage that the voltage of its feedback compensation terminal Vcomp output is likely located higher than resistance R 1, R2 tie point (A), thus electric current from left to right can in resistance R 5, be produced.In addition, in DC power supply, occur when under-voltage, the electric current that flows through resistance R 5 is dextrosinistral.So resistance R 5 is different in the situation that, the flow direction of its electric current is different, can make like this loss of this circuit become large, thereby make the deterioration in accuracy of return difference.Generation for fear of this situation, therefore, this embodiment is provided with three by divider resistance, and the second end of resistance R 5 is connected to the tie point place of resistance R 1, resistance R 2, to guarantee that the voltage at A point place is greater than the voltage of the feedback compensation terminal Vcomp output of PWM chip all the time, thereby make the electric current of resistance R 5 to flow to a left side from the right side, and can not flow to the right side from a left side.Certainly, in other embodiments, as long as can guarantee that resistance R 5 second end places are greater than the voltage of the feedback compensation terminal Vcomp of PWM chip to the voltage on ground when PWM chip works, resistance R 5 second ends also can be connected to the tie point place of resistance R 2, resistance R 3, or, when divider resistance is other quantity, resistance R 5 second ends are connected to the tie point place of other two suitable adjacent resistors.
Fig. 5 is the circuit diagram of under-voltage protecting circuit embodiment tetra-of the present invention, and this under-voltage protecting circuit comprises detection module, control module, return difference module, and wherein, detection module comprises resistance R 1, resistance R 2, resistance R 3 and three end adjustable shunt reference voltage source U.Control module comprises resistance R 4, resistance R 6, voltage-stabiliser tube VZ1 and triode Q1.Return difference module comprises resistance R 5 and diode D1.And DC power supply connects ground, the three input contact resistance R1 of end adjustable shunt reference voltage source U and the tie point (A) of resistance R 2, the plus earth of three end adjustable shunt reference voltage source U by resistance R 1, resistance R 2, resistance R 3 successively.The first end of resistance R 4 connects DC power supply, the second end of resistance R 4 connects the negative electrode of voltage-stabiliser tube VZ1 and the negative electrode of three end adjustable shunt reference voltage source U, the first end of anode connecting resistance R6 of voltage-stabiliser tube VZ1 and the base stage of triode Q1, the second end ground connection of resistance R 6, the grounded emitter of triode Q1, the collector electrode of triode 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 R 5, the second end contact resistance R2 of resistance R 5 and the tie point (B) of resistance R 3.
Principle and the embodiment shown in Fig. 3 of the operation principle of the under-voltage protection shown in this embodiment and generation return difference are basic identical, difference is, owing to having saved diode D2, and, PWM chip when normal operation when under-voltage (DC power supply do not occur), although its feedback compensation terminal Vcomp output is high level, but the voltage of its feedback compensation terminal Vcomp output is likely located the voltage on ground lower than second end (B) of resistance R 5, can in resistance R 5, produce dextrosinistral electric current like this, thereby the voltage of the feedback compensation terminal Vcomp of PWM chip is affected.For avoiding the generation of this situation, so, the divider resistance of this embodiment is provided with three, and the tie point (B) that the second end of resistance R 5 is connected to resistance R 2, resistance R 3 is located, to guarantee that B point place is less than the voltage of the feedback compensation terminal Vcomp output of PWM chip all the time to the voltage on ground.Certainly, in other embodiments, as long as can guarantee that resistance R 5 second end places are less than the voltage of the feedback compensation terminal of PWM chip to the voltage on ground when PWM chip works, resistance R 5 second ends also can be connected to the tie point place of resistance R 1, resistance R 2, or, when divider resistance is other quantity, resistance R 5 second ends are connected to the tie point place of other two suitable 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 comprises detection module, control module, return difference module, and wherein, detection module comprises resistance R 1, resistance R 2, resistance R 3 and three end adjustable shunt reference voltage source U.Control module comprises resistance R 4, resistance R 6, voltage-stabiliser tube VZ1 and triode Q1.Return difference module comprises resistance R 5 and diode D1.And DC power supply connects ground, the three input contact resistance R1 of end adjustable shunt reference voltage source U and the tie point (A) of resistance R 2, the plus earth of three end adjustable shunt reference voltage source U by resistance R 1, resistance R 2, resistance R 3 successively.The first end of resistance R 4 connects DC power supply, the second end of resistance R 4 connects the negative electrode of voltage-stabiliser tube VZ1 and the negative electrode of three end adjustable shunt reference voltage source U, the first end of anode connecting resistance R6 of voltage-stabiliser tube VZ1 and the base stage of triode Q1, the second end ground connection of resistance R 6, the grounded emitter of triode Q1, the collector electrode of triode 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 R 5, the second end contact resistance R2 of resistance R 5 and the tie point (B) of resistance R 3.
The operation principle of the under-voltage protection shown in this embodiment is compared with the operation principle of the under-voltage protection of the embodiment shown in Fig. 3, be not both the principle that return difference produces, specific as follows: when input voltage vin is elevated to while being less than under-voltage protection point upper limit Vup gradually from being less than under-voltage protection point lower limit Vdown, the feedback compensation terminal Vcomp of PWM chip by triode Q1 clamped be low level, PWM chip quits work; When input voltage vin is reduced to while being greater than under-voltage protection point lower limit Vdown gradually from being greater than under-voltage protection point upper limit Vup; owing to just starting the feedback compensation terminal Vcomp of PWM chip, it is high level; the electric current that flows through resistance R 5 and diode D1 produces certain voltage in resistance R 3; thereby the voltage in resistance R 2 and resistance R 3 is raise; be that A point place is to the voltage rising on ground; produce return difference, the feedback compensation terminal Vcomp that makes PWM chip is high level always, the normal operation of PWM chip.In addition, it should be noted that, for guaranteeing that the return difference module that resistance R 5 and diode D1 form can play return difference effect, must guarantee that the second end of resistance R 5 is less than the voltage of the feedback compensation terminal Vcomp of PWM chip to the voltage on ground.Certainly, be more than an embodiment, as long as can guarantee that the second end place of resistance R 5 is less than the voltage of the feedback compensation terminal Vcomp of PWM chip to the voltage on ground, the second end of resistance R 5 also can be connected to the tie point place of resistance R 1, resistance R 2, or, when divider resistance has other quantity, the second end of resistance R 5 also can be connected to the tie point place of other two suitable 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 for converting the input voltage of DC power supply, and this direct current input switch power supply comprises the under-voltage protecting circuit described in PWM chip and above arbitrary embodiment.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.For example, resistance R 4, resistance R 6 can be replaced by the first resistor group, the second resistor group respectively, and the resistance that the first resistor group and the second resistor group can be joined by a plurality of series, parallel or mixing respectively forms.In addition, triode Q1 also can select other switching tube, such as low power metal-oxide-semiconductor etc.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in claim scope of the present invention.
Claims (13)
1. a under-voltage protecting circuit, is connected in PWM chip and DC power supply, it is characterized in that, described under-voltage protecting circuit comprises:
Detection module for detection of the input voltage of DC power supply;
For during point voltage, controlling the out-of-work control module of PWM chip lower than protection at detected input voltage; And
Be connected between described detection module and described control module, and for playing the return difference module of return difference effect; Wherein,
Described detection module comprises three end adjustable shunt reference voltage sources and at least two divider resistances, and described at least two divider resistances are connected between DC power supply and ground, the input of described three end adjustable shunt reference voltage sources connects the tie point of corresponding two adjacent divider resistances, the plus earth of described three end adjustable shunt reference voltage sources, the negative electrode of described three end adjustable shunt reference voltage sources connects described control module, and described return difference module connects the tie point of corresponding two adjacent divider resistances.
2. under-voltage protecting circuit according to claim 1, it is characterized in that, described control module comprises the first resistor group, the second resistor group, voltage-stabiliser tube and switching tube, wherein, the first end of described the first resistor group connects DC power supply, the negative electrode of described voltage-stabiliser tube connects the second end of described the first resistor group and the negative electrode of described three end adjustable shunt reference voltage sources, the first end of the second resistor group described in the anodic bonding of described voltage-stabiliser tube, the second end ground connection of described the second resistor group, the control end of described switching tube connects the anode of described voltage-stabiliser tube, the first end of described switching tube is the output of described control module, the second end ground connection of described switching tube.
3. under-voltage protecting circuit according to claim 2; it is characterized in that; described under-voltage protecting circuit also comprises the second diode; described return difference module comprises return difference resistance and the first diode; wherein; the feedback compensation terminal of PWM chip described in the anodic bonding of described the second diode; the negative electrode of described the second diode connects the first end of described switching tube and the negative electrode of described the first diode; the first end of return difference resistance described in the anodic bonding of described the first diode, the second end of described return difference resistance connects the tie point of corresponding two divider resistances.
4. under-voltage protecting circuit according to claim 2; it is characterized in that; described under-voltage protecting circuit also comprises the second diode; described return difference module comprises return difference resistance; wherein; the feedback compensation terminal of PWM chip described in the anodic bonding of described the second diode, the negative electrode of described the second diode connects the first end of described switching tube and the first end of described return difference resistance, and the second end of described return difference resistance connects the corresponding tie point of at least two divider resistances.
5. under-voltage protecting circuit according to claim 4, is characterized in that, when PWM chip works, the second end place of described return difference resistance is greater than the feedback compensation terminal of PWM chip to the voltage on ground to the voltage on ground.
6. under-voltage protecting circuit according to claim 2; it is characterized in that; described return difference module comprises return difference resistance and the first diode; wherein; the negative electrode of described the first diode connects the first end of described switching tube and the feedback compensation terminal of described PWM chip; the first end of return difference resistance described in the anodic bonding of described the first diode, the second end of described return difference resistance connects the corresponding tie point of at least two divider resistances.
7. under-voltage protecting circuit according to claim 6, is characterized in that, when PWM chip works, the second end place of described return difference resistance is less than the feedback compensation terminal of PWM chip to the voltage on ground to the voltage on ground.
8. under-voltage protecting circuit according to claim 2; it is characterized in that; described return difference module comprises return difference resistance and the first diode; wherein; the feedback compensation terminal of the first end of switching tube and described PWM chip described in the anodic bonding of described the first diode; the negative electrode of described the first diode connects the first end of described return difference resistance, and the second end of described return difference resistance connects the corresponding tie point of at least two divider resistances.
9. under-voltage protecting circuit according to claim 8, is characterized in that, when PWM chip works, the second end place of described return difference resistance is less than the feedback compensation terminal of PWM chip to the voltage on ground to the voltage on ground.
10. under-voltage protecting circuit according to claim 3; it is characterized in that; described at least two divider resistances are the first divider resistance and the second divider resistance, and the tie point of described the first divider resistance and the second divider resistance is connected respectively described three inputs of end adjustable shunt reference voltage source and the second end of return difference resistance.
11. according to the under-voltage protecting circuit described in claim 4 or 5; it is characterized in that; described at least two divider resistances are the first divider resistance, the second divider resistance, the 3rd divider resistance; and described DC power supply connects ground by described the first divider resistance, the second divider resistance, the 3rd divider resistance successively; the second end of described return difference resistance connects the tie point of described the first divider resistance and the second divider resistance, and the input of described three end adjustable shunt reference voltage sources connects the tie point of described the second divider resistance and the 3rd divider resistance.
12. according to the under-voltage protecting circuit described in claim 6 to 9 any one; it is characterized in that; described at least two divider resistances are the first divider resistance, the second divider resistance, the 3rd divider resistance; and described DC power supply connects ground by described the first divider resistance, the second divider resistance, the 3rd divider resistance successively; the input of described three end adjustable shunt reference voltage sources connects the tie point of described the first divider resistance and the second divider resistance, and the second end of described return difference resistance connects the tie point of described the second divider resistance and the 3rd divider resistance.
13. 1 kinds of direct current input switch power supplys, are connected in DC power supply, and described direct current input switch power supply comprises PWM chip, it is characterized in that, described direct current input switch power supply also comprises the under-voltage protecting circuit described in claim 1-9.
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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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| CN103579995B CN103579995B (en) | 2017-02-22 |
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| CN109245052A (en) * | 2018-08-29 | 2019-01-18 | 广州金升阳科技有限公司 | A kind of short-circuit protection circuit and the Switching Power Supply comprising the circuit |
| 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 protection circuit and chip circuit |
| CN110837287A (en) * | 2019-10-17 | 2020-02-25 | 广州金升阳科技有限公司 | Restart circuit |
| CN116978904A (en) * | 2023-07-27 | 2023-10-31 | 屹晶微电子(台州)有限公司 | Power supply voltage stabilizing circuit and integrated chip |
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| CN109245052A (en) * | 2018-08-29 | 2019-01-18 | 广州金升阳科技有限公司 | A kind of short-circuit protection circuit and the Switching Power Supply comprising the circuit |
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| CN110837287A (en) * | 2019-10-17 | 2020-02-25 | 广州金升阳科技有限公司 | Restart circuit |
| CN110837287B (en) * | 2019-10-17 | 2021-03-02 | 广州金升阳科技有限公司 | Restart circuit |
| CN116978904A (en) * | 2023-07-27 | 2023-10-31 | 屹晶微电子(台州)有限公司 | Power supply voltage stabilizing circuit and integrated chip |
| 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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