CN204168124U - A kind of discharge circuit of power supply input filter capacitor and Switching Power Supply - Google Patents
A kind of discharge circuit of power supply input filter capacitor and Switching Power Supply Download PDFInfo
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- CN204168124U CN204168124U CN201420481112.9U CN201420481112U CN204168124U CN 204168124 U CN204168124 U CN 204168124U CN 201420481112 U CN201420481112 U CN 201420481112U CN 204168124 U CN204168124 U CN 204168124U
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Abstract
The application relates to a kind of discharge circuit and Switching Power Supply of power supply input filter capacitor.Wherein Switching Power Supply, comprising: coupling is in an AC-input voltage, the input filter at least comprising an electric capacity; Coupling is in the discharge circuit of input filter, and for according to a discharge signal, be capacitor discharge by a discharging current source and a discharge resistance, discharge circuit comprises: alternating voltage sampling circuit, provides a sampling rectified AC voltage by AC-input voltage; Signal transformation circuit, for providing a time varying signal extracted from sampling rectified AC voltage; Comparator circuit, for comparing sampling rectified AC voltage and time varying signal; Counting circuit, provides discharge signal for the output according to comparator circuit.In the embodiment of the present application, alternating voltage sensor circuit no matter at the high voltage of rectified input signal or low voltage, the change providing scope little or fluctuation.Compared with conventional method, in the embodiment of the present application, to be subject to the instable impact of noise or input ac voltage less for alternating voltage sensor circuit.
Description
Technical field
The application relates to switch power technology field, especially, relates to a kind of discharge circuit and Switching Power Supply of power supply input filter capacitor.
Background technology
Switching regulator AC-DC converter is widely used in household electrical appliance, in computer and electronic equipment, for it provides stabilized voltage power supply.It is little that Switching Power Supply has volume, the advantages such as good stability and high power.Mains switch finds to be widely used in portable type electronic product, and more concern is placed in performance issue always, such as emi protection (EMI) and stand-by power supply.For emi protection, the input port of transducer has one usually directly by the capacitor (X capacitor) that two AC line connect, and is used for suppressing the generation of noise.In traditional power supply, discharge resistance is usually in parallel with X-capacitor to discharge for it, avoids user to get an electric shock when equipment pulls out from supply socket.
Fig. 1 is used to the simple and easy schematic diagram that conventional power source transducer is described.As shown in Figure 1, transducer 100 contains input filter 101, rectifier bridge BD, capacitor C150 and dc-dc (DC/DCConverter).Input filter 101 contains an X-capacitor C100, the 2nd X-capacitor C130, discharge resistor R110 and inductor L120.Input filter 101 for stable AC power Vac, thus reduces electromagnetic interference (EMI).Rectifier bridge BD contains two inputs, two outputs and four diodes.Two inputs of rectifier bridge BD are connected with two outputs of inductor L1.Two outputs of rectifier bridge BD are connected with two terminals of capacitor 150.Rectifier bridge BD is used for rectification AC power, and capacitor 150, for the output of smooth commutation device, generates direct voltage Vbulk and flows to DC-DC converter.DC-DC converter is used for voltage Vbulk to be converted into controlled direct voltage Vo.
In input filter 101, two terminals of an X-capacitor C100 and two terminals of discharge resistor R110 are connected to two terminals of AC power Vac.Two inputs (being also referred to as choking-winding) of inductance L 120 are connected with the two ends of AC power Vac, and two outputs of inductance L 120 are connected with two terminals of the 2nd X-resistor C2.When power supply is in operation, capacitor C100 and C130 is charged by Vac, and AC power Vac stablized by input filter 101, and reduces electromagnetic interference (EMI).When the supply of AC power Vac stops, for example, after pulling out power supply from supply socket, need two capacitor discharges.As shown in fig. 1, traditional power supply 100 has discharge resistor R110 to be that capacitor C100 and C130 discharges.But, when AC power Vac works, because discharge resistor R110 continues consumed power, which reduce the efficiency of power-supply system, cause large standby power.Under idle condition, this standby power can form the substantial portions of the power consumption of power supply.
Various by introduce testing circuit determine that the method whether AC power has stopped being suggested, to reduce power loss, only have when AC power stops, use discharge resistor to X-capacitor discharge.Such as, traditional testing circuit with sampling AC voltage and predetermined constant reference voltage compare.Another kind of traditional testing circuit uses reference voltage, and this voltage is the fixed proportion of the crest voltage of Sample AC voltage.
Application content
In view of this, this application provides a kind of discharge circuit of power supply input filter capacitor, to overcome because discharge resistance is connected in input filter all the time in prior art, thus have influence on efficiency, the increase standby power of system;
And with the constant reference voltage of a predetermined reference voltage or an alternating voltage peak part, cause by noise or input ac voltage de-stabilising effect larger.
For achieving the above object, the application provides following technical scheme:
A discharge circuit for power supply input filter capacitor, comprising:
Rectification circuit, is coupled with the described input filter capacitor being coupled in AC-input voltage, and described rectification circuit is used for exporting a rectified AC voltage according to described AC-input voltage;
Discharge resistance, coupling is in described rectification circuit;
Power switch and discharging current source, series connection coupling is in described discharge resistance;
Charge/discharge control circuit, coupling, in described discharge resistance, for providing a discharge signal to make described power switch conducting, and utilizes described discharging current source to be the electric discharge of described input filter capacitor;
Wherein said charge/discharge control circuit comprises:
Alternating voltage sensor circuit, coupling in described discharge resistance, for obtaining one by the time varying signal that extracts in a sampling rectified AC voltage, and more described sampling rectified AC voltage and described time varying signal;
Counting circuit, for the output according to described alternating voltage sensor circuit, for described power switch provides discharge signal.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, the frequency of described time varying signal is identical with the frequency of described sampling rectified AC voltage, and described time varying signal has the first flat part intersected with the sloping portion of described sampling rectified AC voltage, and the second flat part intersected with the rising part of described sampling rectified AC voltage.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described alternating voltage sensor circuit comprises:
There is the voltage divider of the first resistance and the second resistance, and the sense node that provides described sampling rectified AC voltage between described first and second resistance;
Have the comparator of first input end and the second input, described first input end coupling is in described sense node;
Bidirectional diode equipment, there is coupling in the first terminal of described sense node, and coupling is in the second terminal of described comparator second input, described bidirectional diode equipment has the first diode and the second diode, wherein first terminal is coupled in the positive pole of described first diode and the negative pole of described second diode, the negative pole of described second terminal coupling in described first diode and the positive pole of the second diode;
Capacitor, has coupling in the first terminal of described bidirectional diode equipment, and second terminal of coupling between described comparator second input and ground.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described discharge circuit also comprises an edge detect circuit, and described edge detect circuit coupling in described comparator, and provides a pulse signal at the rising and falling edges that described comparator exports.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described edge detect circuit coupling is in described counting circuit, and described edge detect circuit is for exporting one for the pulse signal of the described counting circuit that resets.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described bidirectional diode equipment comprises two junction diodes.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described bidirectional diode equipment comprises two MOS transistor.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described bidirectional diode equipment comprises two bipolar transistors.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described bidirectional diode equipment comprises two and has sluggish amplifier respectively.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described rectification circuit comprises two diodes.
A discharge circuit for power supply input filter capacitor, comprising:
Rectification circuit, is coupled with the input filter capacitor being coupled in AC-input voltage, and described rectification circuit is used for providing a rectified AC voltage according to described AC-input voltage;
Discharge resistance, coupling is in described rectification circuit;
Power switch and discharging current source, series connection coupling is in described discharge resistance;
Charge/discharge control circuit, coupling, in described discharge resistance, for providing a discharge signal to make described power switch conducting, and utilizes described discharging current source to be the electric discharge of described input filter capacitor;
Wherein said charge/discharge control circuit comprises:
Alternating voltage sampling circuit, for according to providing a sampling rectified AC voltage in described AC-input voltage;
Signal transformation circuit, for providing a time varying signal extracted from described sampling rectified AC voltage;
Comparator circuit, for more described sampling rectified AC voltage and described time varying signal;
Counting circuit, for providing discharge signal according to the output of described comparator circuit.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, the frequency of described time varying signal is identical with the frequency of described sampling rectified AC voltage, and described time varying signal has the first flat part intersected with the sloping portion of described sampling rectified AC voltage, and the second flat part intersected with the rising part of described sampling rectified AC voltage.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described signal transformation circuit comprises:
Bidirectional diode equipment, there is coupling in the first terminal of alternating voltage sampling circuit, with second terminal of coupling in the input of described comparator, described bidirectional diode equipment arranges the first diode and the second diode between described first terminal and the second terminal, the positive pole of wherein said first terminal coupling in described first diode and the negative pole of the second diode, the negative pole of described second terminal coupling in described first diode and the positive pole of the second diode;
Capacitor, has coupling in the first terminal of described bidirectional diode equipment, and second terminal of coupling between described comparator second input and ground.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described discharge circuit also comprises an edge detect circuit, and described edge detect circuit coupling in described comparator, and provides a pulse signal at the rising and falling edges that described comparator exports.
Preferably, in the discharge circuit of above-mentioned power supply input filter capacitor, described edge detect circuit coupling is in described counting circuit, and described edge detect circuit is for exporting one for the pulse signal of the described counting circuit that resets.
A kind of Switching Power Supply, comprising:
Input filter, coupling is in an AC-input voltage, and described input filter at least comprises an electric capacity;
Discharge circuit, coupling is in described input filter, and described discharge circuit is used for according to a discharge signal, is described capacitor discharge by a discharging current source and a discharge resistance,
Wherein said discharge circuit comprises:
Alternating voltage sampling circuit, for exporting a sampling rectified AC voltage according to described AC-input voltage;
Signal transformation circuit, provides a time varying signal extracted from described sampling rectified AC voltage for exporting;
Comparator circuit, for more described sampling rectified AC voltage and described time varying signal;
Counting circuit, for providing discharge signal according to the output of described comparator circuit.
Preferably, in above-mentioned Switching Power Supply, the frequency of described time varying signal is identical with the frequency of described sampling rectified AC voltage, and described time varying signal has the first flat part intersected with the sloping portion of described sampling rectified AC voltage, and the second flat part intersected with the rising part of described sampling rectified AC voltage.
Preferably, in above-mentioned Switching Power Supply, described signal transformation circuit comprises:
Bidirectional diode equipment, there is coupling in the first terminal of alternating voltage sampling circuit, with second terminal of coupling in the input of described comparator, described bidirectional diode equipment is provided with the first diode and the second diode between described first terminal and the second terminal, the positive pole of wherein said first terminal coupling in described first diode and the negative pole of the second diode, the negative pole of described second terminal coupling in described first diode and the positive pole of the second diode;
Capacitor, has coupling in the first terminal of described bidirectional diode equipment, and second terminal of coupling between described comparator second input and ground.
Preferably, in above-mentioned Switching Power Supply, described discharge circuit also comprises an edge detect circuit, and described edge detect circuit coupling in described comparator, and provides a pulse signal at the rising and falling edges that described comparator exports.
Preferably, in above-mentioned Switching Power Supply, described edge detect circuit coupling is in described counting circuit, and described edge detect circuit is for exporting one for the pulse signal of the described counting circuit that resets.
Known via above-mentioned technical scheme, compared with prior art, this application provides a kind of discharge circuit of power supply input filter capacitor, wherein alternating voltage sensor circuit is no matter at the high voltage of rectified input signal or low voltage, the change providing scope little or fluctuation.With the constant reference voltage compare of conventional method by a predetermined reference voltage or an alternating voltage peak part, in the embodiment of the present application, to be subject to the instable impact of noise or input ac voltage less for alternating voltage sensor circuit.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only the embodiment of the application, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the accompanying drawing provided.
Fig. 1 is used to the simple and easy schematic diagram that conventional power source transducer is described;
Fig. 2 is used to the simple and easy schematic diagram that AC-DC power-supply system is described;
Fig. 3 A is used to the simple and easy schematic diagram that alternating voltage sensor circuit is described;
Fig. 3 B is a simple and easy schematic diagram, is used for illustrating that bidirectional diode equipment to be applied in Fig. 3 A in alternating voltage sensor circuit;
Fig. 4 is an oscillogram, is used for various node waveform in alternating voltage sensor circuit 300 is in figure 3 a described;
Fig. 5 is used to the rough schematic that timing circuit is described;
Fig. 6 is used to the rough schematic that counting circuit is described;
Fig. 7 A and 7B is used to the oscillogram illustrating that alternating voltage sensor circuit 300 in figure 3 runs;
Fig. 8 is used to the rough schematic that alternating voltage sensor circuit 800 is described;
Fig. 9 A is used to the rough schematic that alternating voltage sensor circuit is described;
Fig. 9 B shows the bidirectional diode equipment that one contains two bipolar transistors.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present application, be clearly and completely described the technical scheme in the embodiment of the present application, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the application's protection.
According to the embodiment of the application, Fig. 2 is used to the simple and easy schematic diagram that AC-DC power-supply system is described.As shown in Figure 2, power-supply system 200 contains input filter 201, rectifier bridge BD, input capacitor C250 and DC-DC converter 270 (DC-DC Converter).According to the application, transducer 270 can be any suitable power supply changeover device, comprises PFW (pulse frequency modulated) or PWM (pulse width modulation) transducer.Input filter 201 is similar to input filter 101 shown in Fig. 1, for reducing electromagnetic interference, comprises an X-capacitor C100, the 2nd X-capacitor C130, and an inductor L120.But, the discharge resistor R110 in Fig. 1 replace by the discharge circuit 220 in Fig. 2, it is for detecting ac line voltage in real time, and when input ac power stops, within one given period, give X-capacitor discharge.This situation is such as when power supply is extracted from plug, and this discharge circuit by removing X-capacitor discharge resistance, can have lower power loss in the EMI filter stage.
Discharge circuit 220 in Fig. 2, contains two diode D1 and D2, defines the full-wave rectifying circuit of two that has four bridge diode BD.Node 222 between diode D1 and D2, rectification circuit provides commutating voltage Vd.Current-limiting resistance R260 is coupled Vd.Charge/discharge control circuit 280 is at node 224 (mark voltage Va) coupled resistor R160.When AC-input voltage stops, discharge circuit is used in a controlled manner to X-capacitor discharge.According to the above, the application, by comparing the time varying signal of sampling rectification AC-input voltage and a signal transformation circuit, detects the existence of AC-input voltage, described by below.
In the embodiment of figure 2, charge/discharge control circuit 280 comprises high pressure (HV) inductor 230 (HV sensor), timing circuit 240 (Timer & Logic), mains switch K170 and the constant-current source being labeled as I_discharge.High voltage induction device 230 is coupled in node 224, receives commutating voltage Va, and for determining whether input is supply AC power.Before generation discharge signal, timing circuit 240 is for providing time of delay.
According to the embodiment of the application, Fig. 3 A is a rough schematic being used for illustrating alternating voltage sensor circuit.Alternating voltage sensor circuit 300 can be used an example of circuit as Fig. 2 mesohigh induction 230.As shown in Figure 3A, alternating voltage sensor circuit 300 contains the voltage divider with the first resistor R310 and the second resistor R320.Sense node 315 between the first and second resistors provides sampling rectified AC voltage Vb.In certain embodiments, the ratio selecting R310 and R320 is to promote that low-voltage circuit is implemented, for example, in order to keep Vb at 5 volts or lower.In addition, the selecting of resistance of R310 and R320 is to reduce the consumption of power supply in sensor circuit.For example, in certain embodiments, Vac can reach the magnitude of hectovolt, R310 can hundreds of K Ω, R320 can more than 100M Ω.Especially, the large resistance of R320 contributes to limiting electrical source consumption.
Alternating voltage sensor circuit 300 also comprises comparator 350, and it comprises first (positive pole) input and second (negative pole) input, and the first input is coupled with sense node 315.The first terminal 381 of bidirectional diode equipment 370 is coupled with sense node 315, and the second terminal 382 is coupled with second (negative pole) input terminal of comparator.As shown in fig. 3, bidirectional diode equipment 370 has the first diode device 380 and the second diode device 390.The first terminal 381 of bi-directional device and the positive pole of the first diode device 380 and the negative couplings of the second diode device 390, the second terminal 382 of bi-directional device is coupled with the positive pole of the negative pole of the second bipolar tube equipment 380 and the second diode device 390.Alternating voltage sensor circuit 300 also has a capacitor C330 be coupled with bidirectional diode equipment 370 terminal 382.Capacitor 330 is coupled in second (negative pole) of comparator between input terminal and ground G ND.The voltage of second (negative level) input terminal of comparator is appointed as Vc.In certain embodiments, comparator 350 is the hysteresis comparators (comparator with hysteresis) increasing error.In embodiment in figure 3 a, alternating voltage sensor circuit 300 also comprises the edge detect circuit 360 (Rising & Faling Edge Delector) be coupled with comparator 350, at output rising and the drop edge generation pulse signal Y_senser of comparator.As shown in fig. 3, bidirectional diode equipment 370 and capacitor 330 combine and form signal transformation circuit 395.
In figure 3, diode D380 and D390 in double direction diode equipment 370 is shown as semiconductor junction diode.In an alternative embodiment, as shown in Figure 3 B, each diode in bidirectional diode equipment 370 can become diode-connected transistor NPN, or PNP bipolar transistor, or diode-connected NMOS, or POMS transistor.
Fig. 4 is an oscillogram, is used for various node waveform in alternating voltage sensor circuit 300 is in figure 3 a described.As shown in Figure 4, the node 315Vb in Fig. 3, the positive pole input of comparator 350 is full-wave rectification AC-input voltage of a sampling.Voltage Vc is time varying signal, and it is extracted from sampling rectified AC voltage Vb by signal transformation circuit 395.As shown in Figure 4, time varying signal Vc contains rising part 401, sloping portion 403, also has the part 402 and 404 that two substances are mild.Rising part 401 and sloping portion 403 are followed voltage Vb and are changed, and the forward drop of bidirectional diode D380 and D390 causes there is voltage difference between Vb and Vc.In the diagram, the mild portion 402 and 404 of Vc when Vb changes magnitude, caused by the ME for maintenance (voltage holding) of capacitor C330.When the voltage of Vb is greater than Vc, the output of comparator 350 is high level.Positive at the slope of the rising part 401, all-wave Vb of Vc.When the voltage of Vb is less than Vc, the output of comparator 350 is low levels.Negative at the slope of the sloping portion 403, all-wave Vb of Vc.If the voltage of Vb is through the flat part 402 and 404 of Vc, comparator 350 outputs signal upset, from high to low or from low to high.The upset that comparator 350 outputs signal is used for showing that AC-input voltage can exist.In certain embodiments, edge detect circuit 360 is coupled with comparator 350, thus the rising exported at comparator and drop edge produce pulse signal Y_senser.The existence of this pulse signal shows that AC-input voltage exists.
According to the embodiment of the application, Fig. 5 is used to the simple and easy schematic diagram that timing circuit is described.Timing circuit 500 in Fig. 5 is as timing circuit 240 example in Fig. 2.As shown in Figure 5, timing circuit 500 comprises oscillator 501 (Oscillator), logic control 502 (Logic Control) and N-BIT counting circuit 503 (n bit Counter).Oscillator 501 produces CLK pulse signal, as the basic clock signal in counting circuit 503.Unless the reset signal of receiving, otherwise counting circuit 503 will increase, and when N-BIT counter terminates counting, counting circuit 503 produces the output signal being labeled as Y_Discharge.In other words, in the time continued by N-BIT counter, do not have reset signal, discharge signal is triggered.
According to the embodiment of the application, Fig. 6 is used to the rough schematic that counting circuit is described.Counting circuit 600 in Fig. 6 is examples for the N-BITt counting circuit 503 in Fig. 5.In optionally embodiment, also can use other suitable counting circuits.As shown in Figure 6, counting circuit 600 contains a large amount of D flip-flops be connected in series, and it is marked as T1, T2.。。Tn。Input clock signal CLK is coupled with trigger T1.Reset signal is coupled with each trigger.Y-Discharge is as the output of counting circuit.
As shown in Figure 5, logic control circuit 502 is Received signal strength Y_senser from the high voltage induction device Fig. 3 A, and provides a reset signal.As mentioned above, pulse signal Y_senser confirms that AC-input voltage is received.In other words, as long as alternating voltage exists, counting circuit 503 will reset repeatedly.If N-BIT counter does not receive reseting pulse signal, counter continues counting, and cp signal transmission is in trigger.As arrival trigger nth, N-BIT counter disappears, and at this moment a sign shows in during the disappearance of N-BIT counter, and AC-input voltage stops.When N-BIT counter disappears, Y_Discharge turns on the power switch K170, causes capacitor C100 and C130 to be discharged by current source I_source.
Fig. 7 A and 7B is used to the oscillogram illustrating that alternating voltage sensor circuit 300 in figure 3 runs.The above and Fig. 4, Vb are sampling full-wave rectification AC-input voltage, and voltage Vc is the time varying signal being derived from sampling rectified AC voltage Vb.In fig. 7, when Vb and Vc intersects mutually, produce pulse signal Y_senser, show the existence of AC-input voltage.When AC-input voltage stops, pulse signal Y_senser no longer reset counter.In this, when AC-input voltage stops, Vb keeps input ac voltage substantially constant lower than the X-capacitor of Vc, EMS filter.N-BIT counter was propagated, as shown in T blank stage vertical dotted line in Fig. 7 A by each stage of each clock signal clk.After the Tblank time, counter terminates, and provides Y_discharge.Y_discharge signal conduction mains switch K170, makes capacitor C100 and C130 be discharged by current source I_source.Therefore, Vb and Vc starts to decline.It is similar that example in Fig. 7 B illustrates with Fig. 7 A, except when during AC-input voltage stopping, Vb is higher than Vc.In the embodiment of the application, the Tblank time can be selected according to the progression n in the frequency of clock signal clk and N-BIT, (Tblank=n*Tosc, Tosc are the cycles of clock signal clk).Such as, in certain embodiments, Tblank can be set to 50 to 60 milliseconds.’
As previously discussed, in the embodiment of the application, alternating voltage sensor circuit is configured to the time varying signal of providing source from sampling rectified AC voltage, and alternating voltage sensor circuit, by comparing sampling rectified AC voltage and time varying signal, decides the existence of AC-input voltage.The example of Fig. 3 describes the above, and time varying signal obtains by using signal transformation circuit, it comprises bidirectional diode equipment and capacitor.As shown in Figure 4, the crosspoint between Vb and Vc appears in two flat part 402 and 404 of time varying signal Vc.Due to the pressure drop in bidirectional diode equipment, two flat part of Vc compensate from the crest of Vb and trough.Therefore, in the embodiment of the present application, alternating voltage sensor circuit no matter at the high voltage of rectified input signal Vb or low voltage, the change providing scope little or fluctuation.Result, with the constant reference voltage compare of conventional method by a predetermined reference voltage or an alternating voltage peak part, to be subject to the instable impact of noise or input ac voltage less for alternating voltage sensor circuit in the embodiment of the present application.
According to other embodiments of the application, Fig. 8 is used to the rough schematic that alternating voltage sensor circuit 800 is described.Alternating voltage sensor circuit 800 is similar with the alternating current impression circuit 300 in Fig. 3, except the bipolar diode equipment in Fig. 3, by replace by two amplifiers (AMP801 and AMP802) with sluggishness.AMP801 has power supply fan-out capability, and amplifier AMP802 amplifier has sinking fan-out capability simultaneously.
According to other embodiments of the application, Fig. 9 A is used to the rough schematic that alternating voltage sensor circuit 900 is described.As shown in the figure, alternating voltage sensor circuit 900 is similar with the alternating voltage induced current 300 in Fig. 3 A, except the bipolar diode equipment 370 in Fig. 3 replace by two MOS transistor (nmos pass transistor and PMOS transistor).
Fig. 9 B shows bidirectional diode equipment 373, contains two bipolar transistors, and one is NPN bipolar tube, and another is PNP bipolar tube.
In this specification, each embodiment adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar portion mutually see.For the device that embodiment provides, the method provided due to itself and embodiment is corresponding, so description is fairly simple, relevant part illustrates see method part.
To the above-mentioned explanation of provided embodiment, professional and technical personnel in the field are realized or uses the application.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein when not departing from the spirit or scope of the application, can realize in other embodiments.Therefore, the application can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle provided in this article and features of novelty.
Claims (20)
1. a discharge circuit for power supply input filter capacitor, is characterized in that, comprising:
Rectification circuit, is coupled with the input filter capacitor being coupled in AC-input voltage, and described rectification circuit is used for exporting a rectified AC voltage according to described AC-input voltage;
Discharge resistance, coupling is in described rectification circuit;
Power switch and discharging current source, series connection coupling is in described discharge resistance;
Charge/discharge control circuit, coupling, in described discharge resistance, for providing a discharge signal to make described power switch conducting, and utilizes described discharging current source to be the electric discharge of described input filter capacitor;
Wherein said charge/discharge control circuit comprises:
Alternating voltage sensor circuit, coupling in described discharge resistance, for obtaining one by the time varying signal that extracts in a sampling rectified AC voltage, and more described sampling rectified AC voltage and described time varying signal;
Counting circuit, for the output according to described alternating voltage sensor circuit, for described power switch provides discharge signal.
2. the discharge circuit of power supply input filter capacitor according to claim 1, the frequency of described time varying signal is identical with the frequency of described sampling rectified AC voltage, and described time varying signal has the first flat part intersected with the sloping portion of described sampling rectified AC voltage, and the second flat part intersected with the rising part of described sampling rectified AC voltage.
3. the discharge circuit of power supply input filter capacitor according to claim 1, described alternating voltage sensor circuit comprises:
There is the voltage divider of the first resistance and the second resistance, and the sense node that provides described sampling rectified AC voltage between described first and second resistance;
Have the comparator of first input end and the second input, described first input end coupling is in described sense node;
Bidirectional diode equipment, there is coupling in the first terminal of described sense node, and coupling is in the second terminal of described comparator second input, described bidirectional diode equipment has the first diode and the second diode, wherein first terminal is coupled in the positive pole of described first diode and the negative pole of described second diode, the negative pole of described second terminal coupling in described first diode and the positive pole of the second diode;
Capacitor, has coupling in the first terminal of described bidirectional diode equipment, and second terminal of coupling between described comparator second input and ground.
4. the discharge circuit of power supply input filter capacitor according to claim 3, it is characterized in that, also comprise an edge detect circuit, described edge detect circuit coupling in described comparator, and provides a pulse signal at the rising and falling edges that described comparator exports.
5. the discharge circuit of power supply input filter capacitor according to claim 4, is characterized in that, described edge detect circuit coupling is in described counting circuit, and described edge detect circuit is for exporting one for the pulse signal of the described counting circuit that resets.
6. the discharge circuit of power supply input filter capacitor according to claim 3, is characterized in that, described bidirectional diode equipment comprises two junction diodes.
7. the discharge circuit of power supply input filter capacitor according to claim 3, is characterized in that, described bidirectional diode equipment comprises two MOS transistor.
8. the discharge circuit of power supply input filter capacitor according to claim 3, is characterized in that, described bidirectional diode equipment comprises two bipolar transistors.
9. the discharge circuit of power supply input filter capacitor according to claim 3, is characterized in that, described bidirectional diode equipment comprises two and has sluggish amplifier respectively.
10. the discharge circuit of power supply input filter capacitor according to claim 1, is characterized in that, described rectification circuit comprises two diodes.
The discharge circuit of 11. 1 kinds of power supply input filter capacitors, is characterized in that, comprising:
Rectification circuit, is coupled with the input filter capacitor being coupled in AC-input voltage, and described rectification circuit is used to provide a rectified AC voltage according to described AC-input voltage;
Discharge resistance, coupling is in described rectification circuit;
Power switch and discharging current source, series connection coupling is in described discharge resistance;
Charge/discharge control circuit, coupling, in described discharge resistance, for providing a discharge signal to make described power switch conducting, and utilizes described discharging current source to be the electric discharge of described input filter capacitor;
Wherein said charge/discharge control circuit comprises:
Alternating voltage sampling circuit, for providing a sampling rectified AC voltage according to described AC-input voltage;
Signal transformation circuit, for providing a time varying signal extracted from described sampling rectified AC voltage;
Comparator circuit, for more described sampling rectified AC voltage and described time varying signal;
Counting circuit, for providing discharge signal according to the output of described comparator circuit.
The discharge circuit of 12. power supply input filter capacitors according to claim 11, it is characterized in that, the frequency of described time varying signal is identical with the frequency of described sampling rectified AC voltage, and described time varying signal has the first flat part intersected with the sloping portion of described sampling rectified AC voltage, and the second flat part intersected with the rising part of described sampling rectified AC voltage.
The discharge circuit of 13. power supply input filter capacitors according to claim 11, it is characterized in that, described signal transformation circuit comprises:
Bidirectional diode equipment, there is coupling in the first terminal of alternating voltage sampling circuit, with second terminal of coupling in the input of described comparator, described bidirectional diode equipment is provided with the first diode and the second diode between described first terminal and the second terminal, the positive pole of wherein said first terminal coupling in described first diode and the negative pole of the second diode, the negative pole of described second terminal coupling in described first diode and the positive pole of the second diode;
Capacitor, has coupling in the first terminal of described bidirectional diode equipment, and second terminal of coupling between described comparator second input and ground.
The discharge circuit of 14. power supply input filter capacitors according to claim 13, it is characterized in that, also comprise an edge detect circuit, described edge detect circuit coupling in described comparator, and provides a pulse signal at the rising and falling edges that described comparator exports.
The discharge circuit of 15. power supply input filter capacitors according to claim 14, is characterized in that, described edge detect circuit coupling is in described counting circuit, and described edge detect circuit is for exporting one for the pulse signal of the described counting circuit that resets.
16. 1 kinds of Switching Power Supplies, is characterized in that, comprising:
Input filter, coupling is in an AC-input voltage, and described input filter at least comprises an electric capacity;
Discharge circuit, coupling is in described input filter, and described discharge circuit is used for according to a discharge signal, is described capacitor discharge by a discharging current source and a discharge resistance,
Wherein said discharge circuit comprises:
Alternating voltage sampling circuit, for exporting a sampling rectified AC voltage according to described AC-input voltage;
Signal transformation circuit, for exporting a time varying signal extracted from described sampling rectified AC voltage;
Comparator circuit, for more described sampling rectified AC voltage and described time varying signal;
Counting circuit, exports discharge signal for the output according to described comparator circuit.
17. Switching Power Supplies according to claim 16, it is characterized in that, the frequency of described time varying signal is identical with the frequency of described sampling rectified AC voltage, and described time varying signal has the first flat part intersected with the sloping portion of described sampling rectified AC voltage, and the second flat part intersected with the rising part of described sampling rectified AC voltage.
18. Switching Power Supplies according to claim 16, is characterized in that, described signal transformation circuit comprises:
Bidirectional diode equipment, there is coupling in the first terminal of alternating voltage sampling circuit, with second terminal of coupling in the input of described comparator, described bidirectional diode equipment is provided with the first diode and the second diode between described first terminal and the second terminal, the positive pole of wherein said first terminal coupling in described first diode and the negative pole of the second diode, the negative pole of described second terminal coupling in described first diode and the positive pole of the second diode;
Capacitor, has coupling in the first terminal of described bidirectional diode equipment, and second terminal of coupling between described comparator second input and ground.
19. Switching Power Supplies according to claim 18, is characterized in that, also comprise an edge detect circuit, and described edge detect circuit coupling in described comparator, and provides a pulse signal at the rising and falling edges that described comparator exports.
20. Switching Power Supplies according to claim 19, is characterized in that, described edge detect circuit coupling is in described counting circuit, and described edge detect circuit is for exporting one for the pulse signal of the described counting circuit that resets.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420481112.9U CN204168124U (en) | 2014-08-25 | 2014-08-25 | A kind of discharge circuit of power supply input filter capacitor and Switching Power Supply |
| US14/871,201 US9831763B2 (en) | 2014-08-25 | 2015-09-30 | Capacitor discharge circuit for power supply EMI filters |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420481112.9U CN204168124U (en) | 2014-08-25 | 2014-08-25 | A kind of discharge circuit of power supply input filter capacitor and Switching Power Supply |
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| Publication Number | Publication Date |
|---|---|
| CN204168124U true CN204168124U (en) | 2015-02-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420481112.9U Active CN204168124U (en) | 2014-08-25 | 2014-08-25 | A kind of discharge circuit of power supply input filter capacitor and Switching Power Supply |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107425707A (en) * | 2016-05-24 | 2017-12-01 | 三垦电气株式会社 | Capacitor discharge circuit |
| CN108933519A (en) * | 2017-05-22 | 2018-12-04 | 伟诠电子股份有限公司 | Control circuit and method for detecting power receiving state and discharging capacitor voltage according to the detected state |
| CN110445361A (en) * | 2019-08-01 | 2019-11-12 | 成都芯源系统有限公司 | Discharge circuit and discharge method of safety capacitor |
-
2014
- 2014-08-25 CN CN201420481112.9U patent/CN204168124U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107425707A (en) * | 2016-05-24 | 2017-12-01 | 三垦电气株式会社 | Capacitor discharge circuit |
| CN107425707B (en) * | 2016-05-24 | 2019-11-08 | 三垦电气株式会社 | Capacitor discharge circuit |
| CN108933519A (en) * | 2017-05-22 | 2018-12-04 | 伟诠电子股份有限公司 | Control circuit and method for detecting power receiving state and discharging capacitor voltage according to the detected state |
| CN110445361A (en) * | 2019-08-01 | 2019-11-12 | 成都芯源系统有限公司 | Discharge circuit and discharge method of safety capacitor |
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Effective date of registration: 20210202 Address after: No. 1600, Zixing Road, Minhang District, Shanghai 200241 Patentee after: BCD (SHANGHAI) MICRO-ELECTRONICS Ltd. Address before: 200233 No. 800, Xuhui District, Shanghai, Yishan Road Patentee before: BCD Semiconductor Manufacturing Ltd. |