CN103546025A - Offline start-up circuit of switching regulator - Google Patents
Offline start-up circuit of switching regulator Download PDFInfo
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- CN103546025A CN103546025A CN201310488302.3A CN201310488302A CN103546025A CN 103546025 A CN103546025 A CN 103546025A CN 201310488302 A CN201310488302 A CN 201310488302A CN 103546025 A CN103546025 A CN 103546025A
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- 239000003990 capacitor Substances 0.000 claims abstract description 14
- 238000007600 charging Methods 0.000 claims description 12
- 238000002955 isolation Methods 0.000 claims description 10
- 230000008878 coupling Effects 0.000 claims description 9
- 238000010168 coupling process Methods 0.000 claims description 9
- 238000005859 coupling reaction Methods 0.000 claims description 9
- 238000004804 winding Methods 0.000 claims description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
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- 238000010438 heat treatment Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
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Abstract
The invention relates to an offline start-up circuit of a switching regulator, and provides separated or isolated direct-current output for generation of a circuit of a switching pulse. A large resistor is coupled to a direct-current input line and the isolated direct-current output to charge a filter capacitor to a value higher than that of normal voltage. A Zener diode is in serially coupled with the filter capacitor. The combination of the Zener diode is higher than normal Zener in voltage. The diode can respond to capacitor voltage and produce a starting pulse; a power supply is displayed when the offline start-up circuit is powered for the first time.
Description
Technical field
The present invention relates to power line, it is connected on switching regulator, is commonly called as off-line switching regulator.
Background technology
A common full wave bridge rectifier converts ac line voltage to DC pulse, and its part is filtered, and is then applied on switching regulator, to control the energy that offers transducer, secondly, under suitable voltage levvl, for rectifier provides an AC signal.This AC signal adjustment is also applied on filter capacitor, so that a direct current output to be provided.When switching regulator is worked under relatively high frequency, transducer and filter capacitor element may be very effective and relatively little.Yet normal power source line is operated under the 50HZ of half-wave off-line, 100Hz is all-wave, and the magnetic core of such frequency requirement transducer is enough large, and filter capacitor is also enough large, may several thousand millifarads.When a switching regulator is operated under 500KHZ, in the Area Ratio 50Hz situation of its filter capacitor, want little four orders of magnitude.The magnetic core of transducer can be reduced equally, also low-loss FERRITE CORE can be adopted.This power supply conventionally adopts a timing oscillator, both can be synchronously also can be so that phase place latchs the part of loop (PLL), for controlling and stable.Timing oscillator is used to produce a ramp voltage, with the direct current output with after adjustment, compares, and its result is used to adjust the pulse duration of switch, to control the power supply that offers transducer.When direct current output, rise, pressurizer reduces the duty ratio of switch, to reduce output.When direct current output declines, pressurizer increases duty ratio, to increase output.In constant frequency, the variation of duty ratio can change the direct current output of pressurizer.This switching regulator circuit relative complex that can become, to such an extent as to can be the form of integrated circuit (IC).Must provide direct voltage to this IC, so that it can be worked, this power supply of conventionally being exported by the direct current of IC obtains.Yet sort circuit can not self-starting, in the time of energising for the first time, must start separately.This normally connects a resistance and turns back in direct current supply line input in direct current output.When minimum linear voltage, this resistance must flow through enough electric currents, so that IC work.Therefore, resistance value is set.Under the highest power line voltage, resistance must can consume required power, to set rated power.The result of these requirements is, under relative low resistance, to have a relatively high consumption.In other words, resistance heating and relevant to specified high power.Any such power dissipation is wasted, so such startup is worthless.
Summary of the invention
An object of the present invention is, for start-up circuit of switching regulator circuit design, to adopt a large value resistance, to consume some power.
Second object of the present invention is to make the IC work relevant with switching regulator, provides the direct current of a large value resistance to input the capacitor charging to insulating power supply.
The 3rd object of the present invention is to provide on switching regulator IC start-up circuit on a sheet, that is, capacitor charging, when its electric charge reaches default value, produces starting impulse.
Technical solution of the present invention is:
These objects and other object in the following manner, realize in a circuit arrangement.Switching regulator is provided an independent winding, in due course, when peak value is rectified, when can encourage IC, produces one and exchanges output.This rectification is filter capacitor charging, this electric capacity and pressurizer isolation, and it on required design level, has a direct current to export conventionally, and this level determines during by practical application.The coupling of isolation capacitance is worked IC under this design level, for example 15 volts.Electric capacity turns back in direct current input line by a large value resistance, and this will consume some power.When pressurizer, first is connected to direct current input line, this will not have direct current output, and pressurizer can not self-starting.Yet this isolation capacitance will charge by resistance.Start-up circuit comprises a series of Zener diodes that are connected in series, and it has the Zener voltage of a combination, far surpasses the operating voltage of normal electric capacity.This Zener diode string comprises pair of series dropping resistor, and a latch trigger circuit is connected to a Zener diode around.The input of latch is connected to a series resistance around.In the first stage of capacitor charging, magnitude of voltage, lower than Zener voltage, does not have electric current to flow in diode.Then, capacitor charging, to Zener voltage, starts to have electric current to flow into.When the voltage on latch input resistance reaches triggering level, latch is opened, by Zener diode short circuit in parallel.On series zener string, produce a current trigger.It is upper that this current trigger is coupling in IC, and the energy storing on electric capacity starts its work, and switching regulator will be started working.The selection of capacitance, to be provided a discharge time, is enough to guarantee that pressurizer starts reliably.Once pressurizer starts, in the situation that the voltage of the winding of transducer, lower than Zener voltage, charges to isolation capacitance.
Contrast patent documentation: CN202524616U off-line type constant current high-power LED energy-saving lamp driver 201220135227.3
accompanying drawing explanation:
Shown in Fig. 1 is the theory diagram of the switching regulator of description according to the present invention.
Shown in Fig. 2 is the waveform of circuit working in Fig. 1.
Shown in Fig. 3 is the schematic diagram that utilizes the Zener diode type of attachment of NPN transistor first-selection.
embodiment:
As Fig. 1, shown a switching regulator.Its+terminal 10 and-have a normal direct current input on terminal 11.This is conventionally by the output rectification of 110 volts of power lines and part filtering.Conventionally adopt a full-wave rectification bridge (not shown), in minimum value, be less than low linear voltage condition, to such an extent as to be normally input as 150 volts (peak values), but its under high linear voltage condition, they can be up to 190 volts.This part filtered electrical is pressed with a significantly oscillationg component, and this will be eliminated by the work of voltage regulator circuit.
The object of switching regulator is that electric current is worked under high switching frequency, can adopt relatively little filter capacitor and little efficient transducer (or inductance).For this reason, need a high switching speed.Yet because circuit may carry out a large amount of power transfer, switching device must be a high power devices, the ability of restricted upper limiting frequency.Conventionally adopt switching rate within the scope of 20 to 500KHZ, so that 50-100 watt to be provided.Switch 12 may be a power converter or a power MOSFET, on transducer 13, adopts switching current.On winding 14, there is its electric current, make switch close or open.Output winding 15 provides a suitable voltage, and it is by diode 17 rectifications and by electric capacity 18 filtering, so that a direct current output to be provided on terminal 19 and 20.This output supply power is used, and can be selected by user.For example, 5 volts is widely used voltage.Under 10 amperes of specified electric currents, can be by 50 watts.
In the present invention, have an extra winding 16 on transducer 13, it is coupling on diode 21, and its effect is to isolation capacitance 22 chargings, is conventionally charged to 15 volts.This voltage is coupled on pressurizer 24 by line 29, makes 23 work of IC switching regulator circuit.Pressurizer 24 receives an input by line 29, and it is applied on switching regulator circuit by line 25.It is characterized in that, be not activated input pulse on online 26, it will can not start.On switching regulator circuit 23 online 27, receive an induction input, and a pwm pulses is provided on online 28, so that switch 12 work.Because circuit 23 and 24 has traditional function, in switching regulator technology, well-known, they will can further not described.
The core of opening circuit is electric capacity 22, and itself and main power source direct current are exported isolated.Resistance 30 turns back to electric capacity 22 direct current input on terminal 10.The value of resistance 30 is relatively large, makes electric capacity 22 slowly charge to minimum 150 volts.When circuit first starts, at t
0constantly, electric capacity 22 will be recharged, as shown in the figure in Fig. 2.As shown in the figure, it is linear that charging charge is relatively, because resistance 30 is taken as current source.
The series connection string of five Zener diode 31-35 is coupling in around electric capacity 22.These diodes preferably obtain from the knot of traditional transistorized emitter-base stage of ICNPN.The puncture voltage of these diodes is generally 6.3 volts, so the puncture voltage of this series connection string is 31.5 volts, that is, and the electricity 36 shown in Fig. 2.This Zener diode string also comprises resistance 37-39.Once Zener diode starts conducting, will there is electric current to pass through, electric capacity 22 starts electric discharge.This electric current will flow to resistance 37 and 38.Voltage drop on resistance 38 will encourage latch 40, so, by Zener diode 34 and resistance 38 short circuit effectively.This has shortened the time that generation current triggers in series diode string, so that diode 41 is coupled to a starting impulse on pressurizer 24 by line 26.The electric current that offers switching regulator circuit 23 and 24 comes from the energy storing on electric capacity 22.Switch 12 will be started working, and will occur an output voltage on terminal 19-20.At this constantly, conventional pressurizer is by control circuit.As shown in Figure 2, due to winding 16 and the diode 21 of transducer, the voltage on electric capacity 22 is by the level that decays to 15 volts.
T in Fig. 2
1to t
2time in, pressurizer will start.The value of its duration and electric capacity 22 is functional relations, because its discharging current offers switch I C( module 23 and 24 by path 29) required normal current.In this time period, the variation of voltage is also approximate is linear, because IC normal current is relatively constant.When capacitance voltage drops to when being approximately 25.2 volts (voltage drop on four Zener diode 31-33 and 35), zener is by conducting.At time t
2time, voltage regulator circuit will start, and select the probability of such starting component very large.Yet, if started, do not occur, due to the charging current on resistance 30, electric capacity 22 will charge again.When voltage reaches 31.5 volts again, zener is by conducting again, and pressurizer 24 receives a starting impulse.This operation will repeat always, until pressurizer starts.
Shown in Fig. 3 is a first-selected start-up circuit.Wherein, there is part identical with the element of same numeral in Fig. 1.Zener diode is that the knot by emitter-base stage of NPN transistor 43-47 forms.These diodes are coupled in series on resistance 37 and 38, at electric capacity 22 around.Transistorized collector electrode all turns back on electric capacity 22, to such an extent as to they are all reverse biased.Therefore, transistor 43-47 is latched and is isolated on IC circuit epitaxial material substrate.Transistor 48 is lateral PNP transistors that a diode connects, and has the function of diode 41 in Fig. 1.
Example
The structure of the voltage regulator circuit shown in Fig. 1 has adopted the circuit in Fig. 3.This IC is the form that traditional monocrystal silicon PN junction is isolated.Be the value of the element of employing below:
| Element | Value | Unit |
| | 10 | |
| Resistance | ||
| 30 | 500 | Kilohm |
| Resistance 37-39 | 10K | Ohm |
The design of pressurizer itself is under 10 amperes, and the output of one 5 volts is provided, and, can provide the ability of 50 watts that is.Transducer winding 16 and diode 21 produce one normal 15 volts on electric capacity 15.Pulse frequency by line 28 is 100kHz.In the scope of 0 to 10 ampere, the scope of the output voltage of 5 volts is 5.00 volts to 4.95 volts.T shown in Fig. 2
1to t
2the time interval be 0.5 millisecond, the startup of circuit comes from discharging condition, is conventionally about 1.0 milliseconds.
The present invention has been described completely, and detailed description an example.When a people who is skilled in technique reads foregoing description, select alternative or identical element, spirit of the present invention and intention will be apparent.Therefore, the present invention is limited by claim only.
Claims (8)
1. the off-line start-up circuit of a switching regulator, it is characterized in that: in switching regulator power supply, there is a direct current input, a level shift transducer, a pulse width modulating switch, with modulation and control, supply with the electric energy of the direct current input of transducer, the combination of an output rectification filter, a direct current output is provided, pulse-generating circuit provides pwm pulses for switch, be that direct current output can provide direct current output for pulse-generating circuit, a start-up circuit, when power supply is switched on, show its work, comprise: an isolation capacitance can store enough energy, its in start-up time interval for pulse-generating circuit provides power supply, on transducer, there is a winding, be connected in series rectification coupling, for isolation capacitance produces a specified charging voltage, pulse-generating circuit is charged due to specified charging voltage, first resistively couple is between direct current input and electric capacity, and it has a sufficiently high value, and pulse-generating circuit cannot be worked, and the value of the first resistance is enough low, when pulse-generating circuit lost efficacy, is capacitor charging, a plurality of Zener diodes are coupled in series in around isolation capacitance, in conjunction with Zener voltage paranormal charging voltage far away, on the contrary, when the electric charge on isolation capacitance surpasses the Zener voltage of combination, the part of direct current input comes from Zener current, it is the response to Zener current at the beginning that starting impulse produces circuit.
2. the off-line start-up circuit of a kind of switching regulator according to claim 1, is characterized in that: the circuit at the beginning Zener current being given a response, comprising: a latch is at least coupling on a Zener diode; Opening latch is that Zener current is made to response,, increases suddenly Zener current that is; For the Zener current of unexpected increase, pulse-generating circuit produces a starting impulse.
3. the off-line start-up circuit of a kind of switching regulator according to claim 2, is characterized in that: the circuit that electric current is given a response, comprising: second resistance is connected in series on Zener diode, and coupling triggers latch.
4. the off-line start-up circuit of a kind of switching regulator according to claim 2, is characterized in that: the work of pulse-generating circuit is relevant to Voltagre regulator, therefore, when drain current is very little, it is not worked, that is, start pulse and use on Voltagre regulator.
5. the off-line start-up circuit of a kind of switching regulator according to claim 4, is characterized in that: the device of the starting impulse of employing comprises a diode being connected in series, and it is polarized to pass through starting current pulse.
6. the off-line start-up circuit of a kind of switching regulator according to claim 1, is characterized in that: each Zener diode is that NPN transistor base stage is to the knot of emitter.
7. the off-line start-up circuit of a kind of switching regulator according to claim 6, is characterized in that: the collector electrode of NPN transistor turns back on isolation resistance, i.e. reverse bias.
8. the off-line start-up circuit of a kind of switching regulator according to claim 7, it is characterized in that: the device that latch is comprised of a PNP transistor and the coupling of NPN transistor, the second resistively couple is between one of them emitter and base stage of crossing coupling transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310488302.3A CN103546025A (en) | 2013-10-18 | 2013-10-18 | Offline start-up circuit of switching regulator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310488302.3A CN103546025A (en) | 2013-10-18 | 2013-10-18 | Offline start-up circuit of switching regulator |
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| Publication Number | Publication Date |
|---|---|
| CN103546025A true CN103546025A (en) | 2014-01-29 |
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| CN201310488302.3A Pending CN103546025A (en) | 2013-10-18 | 2013-10-18 | Offline start-up circuit of switching regulator |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111682747A (en) * | 2020-05-28 | 2020-09-18 | 深圳市航天新源科技有限公司 | Starting circuit of switching power supply and switching power supply |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070210840A1 (en) * | 2006-03-10 | 2007-09-13 | On-Bright Electronics (Shanghai) Co., Ltd. | System and method for power on reset and under voltage lockout schemes |
| CN103138551A (en) * | 2011-11-30 | 2013-06-05 | 深圳市明微电子股份有限公司 | Control method and device for low current started and low voltage protection circuit |
-
2013
- 2013-10-18 CN CN201310488302.3A patent/CN103546025A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070210840A1 (en) * | 2006-03-10 | 2007-09-13 | On-Bright Electronics (Shanghai) Co., Ltd. | System and method for power on reset and under voltage lockout schemes |
| CN103138551A (en) * | 2011-11-30 | 2013-06-05 | 深圳市明微电子股份有限公司 | Control method and device for low current started and low voltage protection circuit |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111682747A (en) * | 2020-05-28 | 2020-09-18 | 深圳市航天新源科技有限公司 | Starting circuit of switching power supply and switching power supply |
| CN111682747B (en) * | 2020-05-28 | 2021-12-17 | 深圳市航天新源科技有限公司 | Starting circuit of switching power supply and switching power supply |
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Application publication date: 20140129 |