CN101895209B - Power supply circuit and method thereof - Google Patents

Power supply circuit and method thereof Download PDF

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Publication number
CN101895209B
CN101895209B CN2009101454138A CN200910145413A CN101895209B CN 101895209 B CN101895209 B CN 101895209B CN 2009101454138 A CN2009101454138 A CN 2009101454138A CN 200910145413 A CN200910145413 A CN 200910145413A CN 101895209 B CN101895209 B CN 101895209B
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circuit
voltage
loop
power supply
feedback control
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CN101895209A (en
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吴忠文
涂建成
林文轩
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Novatek Microelectronics Corp
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Novatek Microelectronics Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The invention provides a power supply circuit and a method thereof. The power supply circuit is used for feeding back a power supply by a closed loop under a normal mode, and feeding back the power supply by an open loop under a power-saving mode. When the power supply feedback is detected to be in the open loop, and is actually in a zero-output state, the power supply circuit enters a power downstate; and if a back-end circuit requires power supply once again, feedback is cut back to the closed loop, and the power supply circuit restores to normal action.

Description

Power supply circuit and its method
Technical field
The relevant a kind of power supply circuit of the present invention, and particularly about a kind of high efficiency power supply circuit.
Background technology
The display unit such as display or television set has become the article that modern people life can not be perhaps.Display can as the screen of PC, show computer data.See that TV then is one of people's amusement.
Along with the new line of environmental consciousness, electronic installation the more has electricity-saving function.Yet, when traditional electronic devices enters battery saving mode, may be still in running order than the switching power circuit (switching power circuit) of power consumption, so its province's electrical efficiency is limited.
Summary of the invention
The purpose of this invention is to provide a kind of power supply circuit and method, wherein, under battery saving mode, power supply is fed back to out the loop; Under normal mode, power supply is fed back to the loop circuit.When detecting power supply feedback and continue to be in out the loop, and essence is in the zero output state, and then power supply circuit enters power-off (power down) state.
Another object of the present invention provides a kind of power supply circuit and method, and wherein, if back-end circuit needs power supply once again, then feedback switches back to the loop circuit, makes power supply circuit reply regular event.
According to an aspect of the present invention, propose a kind of power supply circuit, provide a supply voltage to a back-end circuit.This power supply circuit comprises: a switching power circuit, control this supply voltage; One loop circuit FEEDBACK CONTROL, under a normal mode, this loop circuit FEEDBACK CONTROL is fed back this supply voltage to this switching power circuit with a loop circuit; And one open circuit feedback control, and under a battery saving mode, this is opened circuit feedback control and opens this supply voltage of circuit feedback to this switching power circuit with one.When this switching power circuit continued to detect this and opens loop and this switching power circuit and be in an essence zero output state, this switching power circuit entered a " shut " mode".
According to a further aspect in the invention, propose a kind of power supply method, provide a supply voltage to a back-end circuit.This power supply method comprises: under a normal mode, feed back this supply voltage with a loop circuit; Under a battery saving mode, open this supply voltage of circuit feedback with one; And wherein ought continue to detect this and open the loop, enter a " shut " mode".
Description of drawings
For foregoing of the present invention can be become apparent, the below will cooperate accompanying drawing that preferred embodiment of the present invention is elaborated, wherein:
Fig. 1 shows the lower wattage power supply supply circuit according to the embodiment of the invention.
Fig. 2 shows according to the loop circuit FEEDBACK CONTROL in the lower wattage power supply supply circuit of the embodiment of the invention and the detailed circuit diagram of opening circuit feedback control.
Fig. 3 shows the circuit diagram according to the switching power circuit of the embodiment of the invention.
Fig. 4 shows the signal waveforms among Fig. 3.
Fig. 5 shows the digital delay loop according to the embodiment of the invention.
Embodiment
In embodiments of the present invention, under battery saving mode, power supply is fed back to out the loop; During regular event, power supply is fed back to the loop circuit.Therefore, when detecting power supply feedback and continue to be in out the loop, and switching power circuit is in the zero output state, and then switching power circuit will enter power-off (power down) state.If back-end circuit needs power supply once again, then feed back switchback to the loop circuit, make power supply circuit can reply regular event.
Fig. 1 shows the lower wattage power supply supply circuit according to the embodiment of the invention.The lower wattage power supply supply circuit is installed in the electronic installation, such as display, lcd screen etc.As shown in Figure 1, lower wattage power supply supply circuit 100 comprises: filter 110, rectifier 120, transformer 130, switching power circuit 140, loop circuit FEEDBACK CONTROL 150, open circuit feedback control 160, capacitor C 1～C2 and diode D1～D2.Lower wattage power supply supply circuit 100 converts voltage source AC_in to direct voltage source, to be supplied to back-end circuit 191.Voltage source AC_in is such as the civil power that is 110V.
190 in small voltage source can be with selectivity direct voltage source in the electronic installation (such as DVI, VGA) etc. by being supplied to back-end circuit 191 after diode D3 and the D4 rectification.But, the confession induced current in small voltage source 190 is lower, and the selectivity direct voltage source not necessarily exists.
Filter 110 is in order to carry out filtering to voltage source AC_in.Filter 110 is such as being electromagnetic interference (EMI) filter.The output voltage of filter 110 is to input to rectifier 120.Rectifier 120 is rectified into direct voltage with the output voltage of filter 110.Rectifier 120 is such as being bridge rectifier.
According to the voltage that feeds back by loop circuit FEEDBACK CONTROL 150, switching power circuit 140 output control voltage V2.This control voltage V2 inputs to the primary side (primary side) of transformer 130.By the coupling of transformer 130, this control voltage V2 is coupled to the primary side (secondary side) of transformer 130.The coupling of switching power circuit 140 control transformers 130; In detail, when the output duty cycle (duty cycle) of switching power circuit 140 is healed when large, during the coupling of transformer 130 more for a long time; Vice versa.In addition, when the output duty cycle of switching power circuit 140 was 0, transformer 130 can not be coupled, further to reduce magnetic loss.
Diode D1 and D2 are with the primary side output voltage rectification of transformer 130, to be supplied to back-end circuit 191.Back-end circuit 191 is such as convergent-divergent circuit (scaler) etc.In addition, for more one advancing to reach voltage stabilizing, between back-end circuit 191 and diode D2, can also comprise low dropout voltage regulator (LDO (LoW Drop Out) regulator).
Loop circuit FEEDBACK CONTROL 150 feeds back to switching power circuit 140 with direct voltage V3 with loop circuit (close loop).Namely, switching power circuit 140 can produce the PWM output signal according to the output voltage V 1 of loop circuit FEEDBACK CONTROL 150, and this PWM output signal can controlled the level of controlling voltage V2.When lower wattage power supply supply circuit 100 was in normal running, loop circuit FEEDBACK CONTROL 150 can be in the loop circuit state, so that voltage V3 is fed back to switching power circuit 140.So, but the load variations of lower wattage power supply supply circuit 100 fast reaction back-end circuit 191.Such as, when load was large, the duty ratio of the PWM output signal that switching power circuit 140 produces (duty cycle) was large; Vice versa.
When entering battery saving mode, hold circuit feedback control 160 can form hold the loop and so that the loop circuit can't form.So, will be so that voltage V3 can't feed back to switching power circuit 140 by loop circuit FEEDBACK CONTROL 150, and also under certain condition, switching power circuit 140 can enter " shut " mode", with further power saving.Because switching power circuit 140 enters " shut " mode", transformer 130 does not carry out Energy Coupling, so transformer 130 can not transmit its energy to capacitor C 2.Because this moment, electric charge can't continue to accumulate in the capacitor C 2, the electric charge in being stored in capacitor C 2 is consumed (such as being consumed by the assembly in the loop circuit FEEDBACK CONTROL 150), and voltage V3 will reduce.If voltage V3 is too low, will causes switching power circuit 140 to be reset, and cause the misoperation of circuit.So in the present embodiment, if when voltage V3 is lower than critical value, switching power circuit 140 can return back to normal mode by " shut " mode".By allowing switch power circuit 140 switch between " shut " mode" and the normal manipulation mode, can reach the power consumption of saving switching power circuit 140.
Fig. 2 shows according to the loop circuit FEEDBACK CONTROL 150 in the lower wattage power supply supply circuit 100 of the embodiment of the invention and the detailed circuit diagram of opening circuit feedback control 160.As shown in Figure 2, loop circuit FEEDBACK CONTROL 150 comprises: optically coupled circuit 151, Voltage Reference controller 152 and resistance R 1.Voltage Reference controller 152 comprises diode D5, resistance R 2 and R3.Open circuit feedback control 160 and comprise transistor Q1, resistance R 4 and R5.
Under normal mode, transistor Q1 is for closing, and voltage feedback paths is optically coupled circuit 151 and Voltage Reference controller 152 (the loop circuit feedback forms), so that voltage V3 feeds back to primary side by the primary side of transformer 130.On the contrary, when being under the battery saving mode, transistor Q1 is conducting, and Voltage Reference controller 152 is activated; Because voltage V4 is clamped down on by transistor Q1, so the loop circuit feedback can't form.Open circuit feedback control 160 and will inhale (sink) electric current (electric current is provided by Voltage Reference controller 152), and can not output current to Voltage Reference controller 152.At this moment, when being under the battery saving mode, because the output duty cycle of switching power circuit 140 can reduce (even being 0), voltage V3 can slowly fall down, because resistance R 2 consumes the electric charge that is stored in the capacitor C 2 with R3.In addition, Voltage Reference controller 152 can allow voltage V3 voltage stabilizing; And when opening loop when existing when not existing (that is loop circuit), Voltage Reference controller 152 can't normal running.
Fig. 3 shows the circuit diagram according to the switching power circuit 140 of the embodiment of the invention.As shown in Figure 3, switching power circuit 140 comprises: PWM produces circuit 310, comparator 320, postpones loop (delay loop) 330, comparator 340 and capacitor C 4.Comparator 320, delay loop 330 form pwm control circuits with comparator 340, produce circuit 310 with control PWM and whether enter " shut " mode".In detail, under power down mode, and the PWM output duty cycle that produces circuit 310 is when being lower than a critical point or being 0%, and then PWM produces circuit 310 and enters " shut " mode", to save power consumption.
The output duty cycle of PWM generation circuit 310 (that is, the duty ratio of its output signal OUT) relevant for voltage V1.The framework that PWM produces circuit 310 need not be particularly limited at this.PWM produces circuit 310 and also comprises an oscillating circuit (oscillator) (not being shown among the figure).
Comparator 320 comparative voltage V1 and reference voltage V DET1Such as, when voltage V1 is higher than reference voltage V DET1, the output signal of comparator 320 is low logic state, vice versa.
Postpone loop 330 and comprise current source 331 and capacitor C 4.When comparator 320 was exported the signal of high logic states, 331 output charges of current source can accumulate in the capacitor C 4, so that the voltage of node N1 rises gradually.When comparator 320 was exported the signal of low logic states, the electric charges that accumulate in the capacitor C 4 can discharge by the internal discharge path of comparator 320, so that the voltage of node N1 reduces to 0.
When the load variations of back-end circuit 191 is very large, may in this case, can not make switching power circuit 140 enter " shut " mode" so that voltage V1 is excessively low, produce otherwise have misoperation.In the present embodiment, preferably under battery saving mode, just make switching power circuit 140 enter " shut " mode".Postponing the generation that loop 330 and comparator 340 can be avoided misoperation, is to make switching power circuit 140 enter mistakenly " shut " mode" in this so-called misoperation.That is in the present embodiment, when the duty ratio of the output signal OUT that enters battery saving mode and switching power circuit 140 was 0, postponing loop 330 can with just output behind this condition delay, enter " shut " mode" with control switch power circuit 140.In more detail, when the duty ratio of the output signal OUT that enters battery saving mode and switching power circuit 140 is 0, preferably through after one period delay period, switching power circuit 140 just enters " shut " mode".Delay period be to decide according to need for a long time.
Comparator 340 comparison node voltage N1 and reference voltage V DET2Such as, when node voltage N1 is higher than reference voltage V DET2The time, the output signal PWM_OFF of comparator 320 is high logic state, vice versa.When output signal PWM_OFF was high logic state, switching power circuit 140 can enter " shut " mode"; Otherwise when output signal PWM_OFF was low logic state, switching power circuit 140 can return back to normal mode.
Transistor 390 is high power transistors, can provide High Level DC Voltage to transformer 130.Resistance R 6 is coupled to ground with an end of transistor 390.The grid of transistor 390 receives by PWM and produces the output signal OUT that circuit 310 produces, and its source electrode is coupled to transformer 130, and its drain electrode is coupled to resistance R 6.For switching power circuit 140, transistor 390 can be external transistor, or built-in transistor.
Fig. 4 shows the signal waveforms among Fig. 3.Now please refer to Fig. 3 and Fig. 4, how to make switching power circuit 140 switch on " shut " mode" and normal mode with explanation.In Fig. 4, OSC represents the output signal that PWM produces the oscillating circuit in the circuit 310.
At first, during soft start (soft start), voltage V1 can rise.Then, when under normal mode, voltage V1 can fix, and PWM produces the duty ratio of the output signal OUT of circuit 310 and also can fix.Then, when time T 1, the load of back-end circuit 191 begins to change, so voltage V1 increases.Such as, when back-end circuit 191 comprised light-emitting diode (LED), if the brightness of LED changes, then for the power supply circuit of the present embodiment, this was load and changes.
During load changed, the duty ratio that PWM produces the output signal OUT of circuit 310 also changed.When load became heavy, it is large that the duty ratio of output signal OUT becomes; Otherwise when load lightened, the duty ratio of output signal OUT diminished.Then, when time T 2, because voltage V1 is lower than reference voltage V DET1, so that the output signal of comparator 320 changes logic high state into by logic low state, so because the charging current of 331 pairs of capacitor C 4 of current source, node voltage N1 begins to rise.
Afterwards, when time T 3, owing to returning back to normal mode, so being increased to, voltage V1 is higher than reference voltage V DET1, then node voltage N1 becomes low logic state (because the low logic output signal of comparator 320 outputs).
Then, when time T 4, enter power down mode, so that voltage V1 is lower than reference voltage V DET1, and the duty ratio of signal OUT is 0% (but at this moment, switching power circuit 140 not yet enters " shut " mode").Because voltage V1 is lower than reference voltage V DET1, so that node voltage N1 begins to rise.When time T 5, node voltage N1 has been higher than reference voltage V DET2(that is, delay period cross) so signal PWM_OFF becomes high logic state, and closes switching power circuit 140 (PWM in the switching power circuit 140 produce circuit 310 and can be closed).As seen from Figure 4, reference voltage V DET2Value can determine time of delay.Refer to time of delay, and under battery saving mode, after the duty ratio of output signal OUT was 0%, after time of delay (between the time T 4 to T5 of Fig. 4 during), switching power circuit 140 just can be closed.At this, switching power circuit 140 is closed representative and is, PWM produces circuit 310 and can be closed, and comparator 320, delay loop 330 and comparator 340 still are in normal operating state.
Then, when time T 6, return back to normal operating state (may be because requirement or the voltage V3 of back-end circuit 191 are lower than critical value), voltage V1 gos up to being higher than reference voltage V DET1, so that node voltage N1 and signal PWM OFF become logic low state in time point T6.So after time point T6, switching power circuit 140 returns back to normal mode.
In Fig. 3, postpone loop 330 and implement with analog circuit.Yet the present invention is not limited to this, postpones loop 330 also to implement with digital circuit.Now please refer to Fig. 5, it shows the digital delay loop according to the embodiment of the invention.As shown in Figure 5, postpone loop 330 and comprise counter 510.When voltage N1 was logic low, counter 510 can be reset.Otherwise, when voltage N1 is logic when high, counter 510 countings.That is, can be considered rolling counters forward voltage N1 (or high logic output signal of count comparator 320).Counter 510 can be exported count value CN to comparator 520.Comparator 520 is this count value CN and counting reference value CN relatively REFWhen count value CN less than counting reference value CN REFThe time, the low logical signal PWM_OFF of comparator 520 outputs; Otherwise, when count value CN equals greatly to count reference value CN REFThe time, the high logical signal PWM_OFF of comparator 520 outputs.Counting reference value CN REFRelevant for the time of delay that postpones loop 330.
The disclosed power supply circuit of the above embodiment of the present invention has multiple advantages, below only enumerates the part advantage and is described as follows.Under battery saving mode, can make switching power circuit enter " shut " mode", to close its inside assembly that consumes energy, further save power consumption.
In sum, although the present invention with the embodiment exposure as above, yet it is not to limit the present invention.The persond having ordinary knowledge in the technical field of the present invention, without departing from the spirit and scope of the present invention, when doing the various changes that are equal to or replacement.Therefore, protection scope of the present invention is when looking accompanying being as the criterion that the application's claim scope defines.

Claims (18)

1. a power supply circuit provides a supply voltage to a back-end circuit, and this power supply circuit comprises:
One switching power circuit is controlled this supply voltage;
One loop circuit FEEDBACK CONTROL, under a normal mode, this loop circuit FEEDBACK CONTROL feeds back to this switching power circuit with a loop circuit with this supply voltage; And
One opens circuit feedback control, and under a battery saving mode, this is opened circuit feedback control and opens the loop with one this supply voltage is fed back to this switching power circuit;
Wherein when this switching power circuit continued to detect this and opens loop and this switching power circuit and be in an essence zero output state, this switching power circuit entered a " shut " mode";
Under this normal mode, this transistor of opening circuit feedback control is for closing, and this loop circuit forms;
When being under this battery saving mode, this this transistor of opening circuit feedback control is conducting, and a Voltage Reference controller of this loop circuit FEEDBACK CONTROL is activated, one node voltage of this Voltage Reference controller is clamped down on by this this transistor of opening circuit feedback control, so this loop circuit can't form; This is opened circuit feedback control an electric current that is provided by this Voltage Reference controller is provided, and this opens the not exportable electric current of circuit feedback control to this Voltage Reference controller; One output duty cycle of this switching power circuit reduces; When this when existing and this loop circuit of opening the loop did not exist, this Voltage Reference controller can't normal running.
2. power supply circuit according to claim 1, it is characterized in that, when this back-end circuit needed power supply, this loop circuit FEEDBACK CONTROL fed back to this switching power circuit with this loop circuit with this supply voltage, made this switching power circuit operate in this normal mode.
3. power supply circuit according to claim 1 is characterized in that, also comprises:
One transformer, this switching power circuit are coupled to a primary side of this transformer, and this back-end circuit and this loop circuit feedback controlled coupling are to a primary side of this transformer;
Wherein, this transformer is coupled to its primary side with an output voltage of this switching power circuit, to become this supply voltage.
4. power supply circuit according to claim 3 is characterized in that, is controlled by this output duty cycle of this switching power circuit during the coupling of this transformer.
5. power supply circuit according to claim 3 is characterized in that, responds the appearance of this loop circuit, and this switching power circuit is controlled this output voltage.
6. power supply circuit according to claim 3, it is characterized in that, when entering this battery saving mode, this is opened circuit feedback control and forms this and open the loop and so that this loop circuit FEEDBACK CONTROL can't form this loop circuit, so, this supply voltage can't feed back to this switching power circuit via this loop circuit.
7. power supply circuit according to claim 1 is characterized in that, when this supply voltage was lower than a critical value, this this " shut " mode" of switch power supply route returned back to this normal mode.
8. power supply circuit according to claim 3 is characterized in that, this loop circuit FEEDBACK CONTROL comprises:
One optically coupled circuit is coupled to this switching power circuit; And
This Voltage Reference controller is coupled to this optically coupled circuit, this this supply voltage of Voltage Reference controller voltage stabilizing;
Wherein, under this normal mode, this optically coupled circuit and this Voltage Reference controller form this loop circuit, so that this supply voltage is fed back to this primary side of this transformer by this primary side of this transformer.
9. power supply circuit according to claim 3 is characterized in that this switching power circuit comprises:
One signal generating circuit is coupled to this transformer; And
One control circuit is coupled to this signal generating circuit, and this control circuit is controlled this signal generating circuit and entered this " shut " mode".
10. power supply circuit according to claim 9 is characterized in that, this control circuit comprises:
One first comparator is coupled to this loop circuit FEEDBACK CONTROL, and this first comparator is one first voltage and one first reference voltage that feed back of this loop circuit FEEDBACK CONTROL relatively, and exports a comparison signal;
One postpones loop, produces a second voltage according to this comparison signal; And
One second comparator, relatively this second voltage and one second reference voltage control signal to this signal generating circuit to export one, and this control signal is controlled this signal generating circuit and whether is entered this " shut " mode".
11. power supply circuit according to claim 10 is characterized in that this delay loop comprises:
One current source; And
One electric capacity receives this comparison signal, and this current source is to this capacitor charging.
12. power supply circuit according to claim 9 is characterized in that, this control circuit comprises:
One first comparator is coupled to this loop circuit FEEDBACK CONTROL, and this first comparator is one first voltage and one first reference voltage that feed back of this loop circuit FEEDBACK CONTROL relatively, and exports a comparison signal;
One counter is counted this comparison signal and is produced a count signal; And
One second comparator, relatively this count signal and a counting reference value control signal to this signal generating circuit to export one, and this control signal is controlled this signal generating circuit and whether is entered this " shut " mode".
13. a power supply method provides a supply voltage to a back-end circuit, this power supply method comprises:
Under a normal mode, to feed back this supply voltage, this loop circuit is controlled by a loop circuit FEEDBACK CONTROL by a loop circuit;
Under a battery saving mode, open the loop feeding back this supply voltage by one, this is opened the loop and opens circuit feedback control by one and controlled; And
Wherein ought continue to detect this and open the loop, enter a " shut " mode", wherein,
Under this normal mode, this transistor of opening circuit feedback control is for closing, and this loop circuit forms;
When being under this battery saving mode, this this transistor of opening circuit feedback control is conducting, and a Voltage Reference controller of this loop circuit FEEDBACK CONTROL is activated, one node voltage of this Voltage Reference controller is clamped down on by this this transistor of opening circuit feedback control, so this loop circuit can't form; This is opened circuit feedback control an electric current that is provided by this Voltage Reference controller is provided, and this opens the not exportable electric current of circuit feedback control to this Voltage Reference controller; When this when existing and this loop circuit of opening the loop did not exist, this Voltage Reference controller can't normal running.
14. power supply method according to claim 13 is characterized in that, also comprises:
When entering this battery saving mode, form this and open the loop and interrupt this loop circuit.
15. power supply method according to claim 13 is characterized in that, also comprises:
When this supply voltage is lower than a critical value, return back to this normal mode by this " shut " mode".
16. power supply method according to claim 13 is characterized in that, also comprises:
Utilize this loop circuit to come this supply voltage of voltage stabilizing.
17. power supply method according to claim 13 is characterized in that, also comprises:
One first voltage and one first reference voltage that relatively feed back by this loop circuit are to export a comparison signal;
Produce a second voltage according to this comparison signal; And
Relatively this second voltage and one second reference voltage, to export a control signal, whether this control signal control enters this " shut " mode".
18. power supply method according to claim 13 is characterized in that, also comprises:
One first voltage and one first reference voltage that relatively feed back by this loop circuit, and export a comparison signal;
One counter is counted this comparison signal and is produced a count signal; And
One second comparator, relatively this count signal and is counted reference value, and to export a control signal, whether this control signal control enters this " shut " mode".
CN2009101454138A 2009-05-19 2009-05-19 Power supply circuit and method thereof Active CN101895209B (en)

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CN105867502B (en) * 2016-05-18 2017-10-10 湖州绿明微电子有限公司 LDO pressure regulators, alternating current equipment
CN112260530B (en) * 2020-12-22 2021-03-12 深圳英集芯科技股份有限公司 Power supply soft start control circuit, control chip and control device
CN114696426A (en) * 2022-04-29 2022-07-01 深圳市正浩创新科技股份有限公司 Power supply control method and device and power supply equipment

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