CN203406783U - Step-down circuit and switching power supply - Google Patents
Step-down circuit and switching power supply Download PDFInfo
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- CN203406783U CN203406783U CN201320499420.XU CN201320499420U CN203406783U CN 203406783 U CN203406783 U CN 203406783U CN 201320499420 U CN201320499420 U CN 201320499420U CN 203406783 U CN203406783 U CN 203406783U
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Abstract
The utility model provides a step-down circuit and a switching power supply, which comprise a power supply input end, a reference voltage supply module, a comparator used for comparing the output voltage of the step-down circuit with a reference voltage, a controlled first switch, a controlled second switch, a controlled third switch, an RC circuit used for controlling the working frequency of the step-down circuit, and an LC resonance circuit used for storing electric energy and providing the output voltage of the step-down circuit. According to the technical scheme of the utility model, the step-down circuit has the advantages of lower cost and easy realization. Meanwhile, the working frequency and the output voltage range of the step-down circuit can be adjusted according to needs.
Description
Technical field
The utility model relates to a kind of reduction voltage circuit for Switching Power Supply, particularly a kind of reduction voltage circuit and Switching Power Supply thereof for the Switching Power Supply used at vehicle electronics.
Background technology
In vehicle electronics, the classification of waterproof of instrument is more and more higher.The circuit board of gauge internal should meet caloric value can not be too large, also will meet the alap requirement of instrument power consumption to car load.In order to improve power-efficient and to reduce power consumption simultaneously, instrument adopts switching power circuit conventionally.
Current most of switching power circuit adopts complicated integrated power supply chip or complicated starting of oscillation and voltage stabilizing circuit to realize.Wherein, for direct-current switch power supply, adopt integrated chip or complicated analog circuit scheme more.Integrated chip scheme cost is very high, and complicated analog circuit exists the problem that reliability is low.In addition, two schemes is due to the limitation of design, and the operating frequency when operation at full load is generally nonadjustable, and the input and output of power supply are simultaneously also non-adjustable, even if adjustable its adjustment process is also very complicated.
Therefore, need a kind of with low cost, realize simple and can according to circumstances adjust frequency and the reduction voltage circuit of the switching circuit of power supply input/output bound.
Summary of the invention
The utility model is intended to propose a kind of reduction voltage circuit of the Switching Power Supply addressing the above problem.
This reduction voltage circuit comprises: for electrical input; Reference voltage provides module, for reference voltage is provided; Comparator, for comparing output voltage and the reference voltage of reduction voltage circuit; The first switch, its control end receives the output of comparator, and its input connects for electrical input; Second switch, its control end connects the output of the first switch, and its input connects for electrical input, and its output connects RC circuit; The 3rd switch, its control end connects the output of second switch by RC circuit, and its input connects for electrical input, and its output connects LC resonant circuit; Wherein, the output voltage of reduction voltage circuit is provided by LC resonant circuit.
Further, the first switch of this reduction voltage circuit is PNP pipe, and its control end, input and output are respectively the base stage of this PNP pipe, emitter and collector.Preferably, the output of this first switch is also connected with the control end of second switch by the first resistance-grounded system and by the second resistor respectively.
Further, the second switch of this reduction voltage circuit is PNP pipe, and its control end, input and output are respectively the base stage of this PNP pipe, emitter and collector.Preferably, the input of this second switch connects for electrical input by the 3rd resistor.
Further, the 3rd switch of this reduction voltage circuit is NPN pipe, and its control end, input and output are respectively the base stage of this NPN pipe, collector and emitter.
Further, the RC circuit of this reduction voltage circuit comprises the second capacitor and the 4th resistor, wherein one end of the second capacitor and one end of the 4th resistor are all connected the output of second switch, the other end ground connection of the second capacitor, and the other end of the 4th resistor connects the control end of the 3rd switch.
Further, the LC resonant circuit of this reduction voltage circuit comprises inductor, the first capacitor and the first diode, wherein one end of inductor and the negative electrode of the first diode are all connected the output of the 3rd switch, the other end of inductor is by series connection the first capacitor grounding, the plus earth of the first diode.Preferably, this LC resonant circuit also comprises the 5th resistor, the 6th resistor, wherein after inductor and the 5th resistor in series, and is connected with the series circuit that the 6th resistor forms by the first capacitor.
Further, it is voltage stabilizing didoe that the reference voltage of this reduction voltage circuit provides module, its plus earth, and its negative electrode connects the normal phase input end of comparator.
In addition, the utility model also provides a kind of Switching Power Supply that comprises above-mentioned reduction voltage circuit.
This reduction voltage circuit, except comprising necessary element, only adopts comparator as power feedback, with simple controlled switch, controls current flowing.The simple R C circuit that resistor and capacitor form simultaneously can be controlled the operating frequency of reduction voltage circuit, the LC resonant circuit that inductor, capacitor form can storage of electrical energy and the output voltage of reduction voltage circuit is provided, and modal voltage-stabilizing device can be controlled the output voltage of reduction voltage circuit.Therefore, reduction voltage circuit design of the present utility model, at utmost to have reduced components and parts, has reduced cost and has been easy to and realized, and can adjust as required operating frequency and the output voltage range of reduction voltage circuit simultaneously.
Accompanying drawing explanation
Only with reference to accompanying drawing, provide explanation by way of example now, wherein:
Fig. 1 is according to the exemplary circuit diagram of the reduction voltage circuit of Switching Power Supply of the present utility model.
Embodiment
Fig. 1 illustrates the circuit diagram of the reduction voltage circuit of illustrative switch power supply of the present utility model.This reduction voltage circuit mainly comprises direct current supply input U12, comparator U1A, reference voltage provides module, first, second, and third switch, for the RC circuit of controlled hypotension circuit work frequency and for energy storage so that the LC resonant circuit of output voltage to be provided.Wherein, reference voltage provides module to be realized by voltage stabilizing didoe D1.First, second, and third switch is realized by PNP pipe Q1, PNP pipe Q2 and NPN pipe Q3 respectively.The voltage at the capacitor C2 two ends in LC resonant circuit is as the output voltage of the voltage output end V_OUT of this reduction voltage circuit.
First the structure of reduction voltage circuit is described with reference to figure 1.
The in-phase input end (+) of comparator U1A by resistor R1, is connected to direct current supply input U12 respectively and by the reverse ground connection of voltage stabilizing didoe D1, voltage stabilizing didoe D1 provides the reference voltage of the in-phase input end that is applied to comparator U1A.The inverting input (-) of comparator U1A is connected with the voltage output end V_OUT of reduction voltage circuit through resistor R2, and the voltage output end V_OUT of reduction voltage circuit forms the feedback loop of the inverting input that is connected to comparator U1A through resistor R2.The base stage that the output COMP OUT of comparator U1A connects respectively PNP pipe Q1 with by resistor R3, be connected direct current supply input U1A, the output COMP OUT of resistor R1 and R3 comparator U1A in series is to the feedback loop of in-phase input end.
The emitter of PNP pipe Q1 connects direct current supply input U12, and the collector electrode of Q1 is respectively by resistor R4 ground connection and by the base stage of resistor R5 connection PNP pipe Q2.The emitter of PNP pipe Q2 connects direct current supply input U12 by resistor R6, and the collector electrode of Q2 is respectively by capacitor C1 ground connection and the base stage that is connected NPN pipe Q3 by resistor R7.Capacitor C1 and resistor R7 have formed the RC circuit in reduction voltage circuit.The collector electrode of NPN pipe Q3 is connected with direct current supply input U12, and the emitter of Q3 is respectively by one end of the reverse ground connection of diode D2 and connection inductor L1.
The other end of inductor L1 is connected with one end of resistor R8, and the series circuit that resistor R8 forms with capacitor C2 and capacitor R9 is connected and through resistor R2, fed back the inverting input that accesses comparator U1A, the other end ground connection of capacitor C2.The voltage at the series circuit two ends that capacitor C2 and capacitor R9 form i.e. the output voltage V of this reduction voltage circuit
output.Wherein, inductor L1, resistor R8 and R9, capacitor C2 and diode D2 have formed LC resonant circuit.Resistor R10 is connected between voltage output end V_OUT and ground, as output loading.
To the operation principle of this reduction voltage circuit be described now.
First, when direct current supply input U12(input voltage is V
input, V
input>V
output) while powering on, the stable state of voltage stabilizing didoe D1 in reverse breakdown.The voltage of the in-phase input end of comparator U1A equals the burning voltage (being reference voltage) of voltage stabilizing didoe D1, and the voltage of the inverting input of comparator U1A equals the output voltage V of reduction voltage circuit
output, V now
outputfor 0V.Due to the voltage of the in-phase input end of the comparator voltage higher than inverting input, so the output COMP OUT of comparator U1A output high level (equals the input voltage V of direct current supply input U12
input, V
inputfor just), this high level is fed into the base stage of PNP pipe Q1.The voltage of PNP pipe Q1 emitter also equals input voltage V
input; The collector electrode of PNP pipe Q1 is by resistor R4 ground connection, and collector voltage is 0V, and PNP pipe Q1 turn-offs.
Now, the base stage of PNP pipe Q2 is by resistor R5 and R4 series connection ground connection, and the base voltage of Q2 is 0V.The emitter of PNP pipe Q2 connects direct current supply input U12 by resistor R6, because emitter base voltage is higher than its conducting voltage, and PNP pipe Q2 conducting.Electric current charges to capacitor C1 through resistor R6 by direct current supply input U12, and the voltage at C1 two ends raises gradually.
Along with capacitor, C1 constantly charges, when the base-emitter voltage of NPN pipe Q3 is during higher than its conducting voltage, and Q3 conducting.Electric current charges to capacitor C2 through inductor L1, resistor R8, R9 by direct current supply input U12, and the voltage at C2 two ends constantly raises.
When the raise output voltage V of the voltage output end V_OUT that makes reduction voltage circuit of the voltage at capacitor C2 two ends
outputduring higher than the voltage of voltage regulation of voltage stabilizing didoe D1, be that the voltage of inverting input of comparator U1A is higher than the reference voltage of in-phase input end, the outputting cutting of the output COMP OUT of comparator U1A changes low level (for 0V) into, now the base voltage of PNP pipe Q1 is 0V, the emitter base voltage of Q1 is greater than its conducting voltage, and PNP pipe Q1 switches to conducting by shutoff.
Now, the base voltage of the PNP of conducting originally pipe Q2, because the conducting of PNP pipe Q1 is risen, makes the emitter base voltage of PNP pipe Q2 lower than its conducting voltage, causes PNP pipe Q2 to switch to shutoff by conducting.Capacitor C1 starts electric discharge, and its both end voltage reduces gradually, and the base voltage of NPN pipe Q3 also reduces gradually.When the base-emitter voltage of NPN pipe Q3 is during lower than its conducting voltage, Q3 switches to shutoff by conducting.
At NPN pipe Q3, close and have no progeny, the LC resonant circuit consisting of inductor L1, resistor R8, R9 and capacitor C2 starts electric discharge, and keeping provides output voltage to the voltage output end V_OUT of reduction voltage circuit, and now diode D2 plays afterflow.Capacitor C2 electric discharge causes the lower voltage at its two ends, when the lower voltage at C2 two ends is to the output voltage V that makes reduction voltage circuit
outputduring again lower than the voltage of voltage regulation of voltage stabilizing didoe D1, the inverting input of comparator U1A is again lower than the voltage of in-phase input end, and now the output voltage of the output COMP OUT of comparator U1A switches to high level again.
Thus, by the output voltage of reduction voltage circuit and the voltage of voltage regulation of voltage stabilizing didoe D1 that are relatively fed to by feedback loop, output repetitive cycling between high level and low level of the output COMP OUT of comparator U1A is switched, and then made Q1, Q2 and Q3 repetitive cycling switching between turn-on and turn-off respectively.The turn-on and turn-off of NPN pipe Q3 are switched LC resonant circuit repetitive cycling between charging and discharging state, so that the output voltage V of the voltage output end V_OUT of reduction voltage circuit
outputremain the burning voltage of voltage stabilizing didoe D1, so the voltage of voltage regulation of voltage stabilizing didoe D1 has determined the output voltage of this reduction voltage circuit.
In above-mentioned repetitive cycling process, the emitter voltage of NPN pipe Q3 equals the output voltage V of reduction voltage circuit all the time
outputtherefore in RC circuit, the speed that discharges and recharges of capacitor C1 has determined that the NPN pipe base voltage of Q3 and the difference of emitter voltage reach the speed of base-emitter conducting voltage or shutoff voltage, the operating frequency that is RC circuit has determined the NPN pipe conducting of Q3 and the switching frequency of off state, and then has determined the switching frequency of the charging and discharging state of LC resonant circuit.The switching of the charging and discharging state of LC resonant circuit causes by comparing the output voltage V of reduction voltage circuit
outputand the magnitude relationship between the voltage of voltage regulation of voltage stabilizing didoe D1, so that the output of comparator U1A is switched at high level and low level.Hence one can see that, and RC circuit has determined the operating frequency of this reduction voltage circuit.
Like this, by changing the voltage of voltage regulation of voltage stabilizing didoe D1, can regulate the output voltage V of the reduction voltage circuit of this Switching Power Supply
output.And by the capacitor C1 in adjusting RC circuit and the parameter of resistor R7, can adjust the operating frequency of reduction voltage circuit.
In practice, as required, reference voltage provides module also can adopt voltage stabilizing circuit, and voltage stabilizing chip etc. substitute.First, second, and third switch also can all or part of employing field effect transistor, comparator, even adopts the thyristor that is applicable to high voltage and large electric current as switch element.
Should be appreciated that above-mentioned example is only illustrative and is not used in the scope that limits the application.In the situation that the spirit that does not depart from the application in the form of embodiment described herein and details, make various to delete, substitute and change be apparent for those skilled in the art.In addition, disclosing of the application is appreciated that and comprises that herein clear and definite or implicit disclosed arbitrary characteristics or Feature Combination or its summarize arbitrarily.
Claims (11)
1. a reduction voltage circuit, is characterized in that described reduction voltage circuit comprises:
For electrical input;
Reference voltage provides module, for reference voltage is provided;
Comparator, for output voltage and the described reference voltage of more described reduction voltage circuit;
The first switch, the control end of described the first switch receives the output of described comparator, and the input of described the first switch connects described for electrical input;
Second switch, the control end of described second switch connects the output of described the first switch, and the input of described second switch connects described for electrical input, and the output of described second switch connects RC circuit;
The 3rd switch, the control end of described the 3rd switch connects the output of described second switch by described RC circuit, and the input of described the 3rd switch connects described for electrical input, and the output of described the 3rd switch connects LC resonant circuit;
Wherein, the output voltage of described reduction voltage circuit is provided by LC resonant circuit.
2. reduction voltage circuit as claimed in claim 1, wherein said the first switch is PNP pipe, the control end of described the first switch, input and output are respectively the base stage of described PNP pipe, emitter and collector.
3. reduction voltage circuit as claimed in claim 2, the output of wherein said the first switch is also connected with the control end of described second switch by the first resistance-grounded system and by the second resistor respectively.
4. reduction voltage circuit as claimed in claim 1, wherein said second switch is PNP pipe, the control end of described second switch, input and output are respectively the base stage of described PNP pipe, emitter and collector.
5. reduction voltage circuit as claimed in claim 4, the input of wherein said second switch connects described for electrical input by the 3rd resistor.
6. reduction voltage circuit as claimed in claim 1, wherein said the 3rd switch is NPN pipe, the control end of described the 3rd switch, input and output are respectively the base stage of described NPN pipe, collector and emitter.
7. reduction voltage circuit as claimed in claim 1, wherein said RC circuit comprises the second capacitor and the 4th resistor, one end of described the second capacitor and one end of described the 4th resistor are all connected the output of described second switch, the other end ground connection of described the second capacitor, the other end of described the 4th resistor connects the control end of described the 3rd switch.
8. reduction voltage circuit as claimed in claim 1, wherein said LC resonant circuit comprises inductor, the first capacitor and the first diode, one end of described inductor and the negative electrode of described the first diode are all connected the output of described the 3rd switch, the other end of described inductor is by described the first capacitor grounding of series connection, the plus earth of described the first diode.
9. reduction voltage circuit as claimed in claim 8, wherein said LC resonant circuit also comprises the 5th resistor, the 6th resistor, after described inductor and described the 5th resistor in series, and connected with the series circuit that described the 6th resistor forms by described the first capacitor.
10. reduction voltage circuit as claimed in claim 1, it is voltage stabilizing didoe that wherein said reference voltage provides module, the plus earth of described voltage stabilizing didoe, its negative electrode connects the normal phase input end of described comparator.
11. 1 kinds of Switching Power Supplies, comprise the reduction voltage circuit as described in any one in claim 1 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320499420.XU CN203406783U (en) | 2013-08-15 | 2013-08-15 | Step-down circuit and switching power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320499420.XU CN203406783U (en) | 2013-08-15 | 2013-08-15 | Step-down circuit and switching power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203406783U true CN203406783U (en) | 2014-01-22 |
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ID=49942703
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320499420.XU Expired - Lifetime CN203406783U (en) | 2013-08-15 | 2013-08-15 | Step-down circuit and switching power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203406783U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106251812A (en) * | 2016-08-16 | 2016-12-21 | 深圳天珑无线科技有限公司 | A kind of backlight drive circuit and electronic equipment |
| CN107909992A (en) * | 2017-12-04 | 2018-04-13 | 成都星达微科技有限公司 | A kind of campus dormitory active noise reduction system of powered stable |
-
2013
- 2013-08-15 CN CN201320499420.XU patent/CN203406783U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106251812A (en) * | 2016-08-16 | 2016-12-21 | 深圳天珑无线科技有限公司 | A kind of backlight drive circuit and electronic equipment |
| CN107909992A (en) * | 2017-12-04 | 2018-04-13 | 成都星达微科技有限公司 | A kind of campus dormitory active noise reduction system of powered stable |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20181224 Address after: 241009 No. 18 Tianzhushan Road, Wuhu City, Anhui Province Patentee after: Continental automotive body electronic system (Wuhu) Co.,Ltd. Address before: 241009 No. 27 Yinhu Road, Wuhu Economic and Technological Development Zone, Anhui Province Patentee before: Continental automotive electronics (Wuhu) Co.,Ltd. |
|
| TR01 | Transfer of patent right | ||
| CX01 | Expiry of patent term |
Granted publication date: 20140122 |
|
| CX01 | Expiry of patent term |