CN1333513C - Switching power source circuit - Google Patents
Switching power source circuit Download PDFInfo
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- CN1333513C CN1333513C CNB2004100032579A CN200410003257A CN1333513C CN 1333513 C CN1333513 C CN 1333513C CN B2004100032579 A CNB2004100032579 A CN B2004100032579A CN 200410003257 A CN200410003257 A CN 200410003257A CN 1333513 C CN1333513 C CN 1333513C
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Abstract
Provided is a switching circuit capable of triggering with no trouble where an abnormal sound is prevented from occurring at intermittent oscillation. A voltage detecting circuit 1 detects decrease in a forward voltage which is induced at the drive coil T1 of a pulse transformer at intermittent oscillation. A peak current limit circuit 3 is operated when decrease in the forward voltage is detected at the voltage detecting circuit. An overcurrent detecting circuit 6 operates when the peak current limit circuit is operated to reduce the current flowing a power transistor. An input voltage detecting circuit 15 stops the peak current limit circuit during the period until it comes to be a normal state after a power supply is turned on.
Description
Technical field
The present invention relates to possess underloading intermittent oscillation corresponding circuits to realize the switching power circuit of low consumption electrification.
Background technology
As everyone knows, in existing switching power circuit, particularly in RCC (ringing chokeconverter) power mode, intermittent oscillation takes place during underloading.But, produce ' Pi, Pi ' sound and ' Bi at this intermittent oscillation state, Bi ' sound is known as unusual vibration, is taken as the state that takes place of not allowing.Yet this state has the effect that reduces consumption loss electric power, if use such as when standby is very effective in the low consumption electrification that realizes circuit.But, be practicability not because so problem of abnormal sound that produces, reality are arranged.
Therefore, the energy intermittent oscillation work if foregoing circuit does not produce abnormal sound when underloading, then when the switching power circuit standby, present intermittently (being known as burst mode (burst mode)) same effect of the underloading used with the power circuit that utilizes internal oscillator, the consumption electric power that can reduce when standby etc.
The reason that particularly can hear abnormal sound during the underloading intermittent oscillation of RCC power mode be because, if generation intermittent oscillation, then start action repeatedly, the rechargeable energy needs of the electrochemical capacitor that links to each other with secondary lead-out terminal etc. are a lot, for this energy is provided, power transistor flows through very big pulse current, so frequency of oscillation is slack-off, and enters audio region.Thisly can constantly take place repeatedly.
Fig. 5 is the switching power circuit that prevents to hear abnormal sound when the underloading intermittent oscillation.R1 is the big electric power type power resistor that is used to detect the electric current that flows through power transistor TR2.This circuit structure be for the following situation of correspondence to obtain same effect: follow the rising of the input voltage of AC power supplies, the parameter (r2) that compensates is added to overcurrent detects with transistor T R1 etc. for making overcurrent protection starting point among the control system S change (also action early during the same electrical flow valuve).Therefore; this circuit mode is: follow the variation of input voltage; to change the electric current I 1 that circuit overcurrent protection compensating resistance r2 that the proportional changing unit of voltage links to each other flows through with this, and mix with the voltage V1 that power resistance R 1 obtains, and overcurrent be detected with transistor T R1 move by current detecting.
Promptly; utilize this mode; not to change detection power transistor T R2 to flow through the detection resistance value self of electric current and detection voltage is risen, but the circuit overcurrent protection compensation is similarly diminished to obtain same effect with value and the burst mode (burstmode) of resistance r2.Thus, set resistance value r2＞r3, when switch SW 1 is opened, make it become the resistance value also littler (state that resistance r2 is in parallel with resistance r3) of equal valuely, make the electrorheological that flows through circuit overcurrent protection compensation usefulness resistance big than r2.
Thus, the action of circuit overcurrent protection begins the level step-down, and the electric current that power transistor TR2 is flow through is the current value lower than initial set value, and circuit overcurrent protection moves quickly.This is to utilize according to the overcurrent protection compensation of input voltage to use voltage, makes overcurrent detect voltage of equal valuely and raises, and the overcurrent protection starting point is moved early.
Therefore, the drain current Id of power transistor TR2 only flows through very little, and then ' Pi, the abnormal sound of Pi ' sound etc. just be can't hear.
[patent documentation 1]
The spy opens the 2001-238440 communique
Move with intermittent oscillation during underloading during standby etc., to realize the low consumption electrification of circuit.The peak value of the peak current that produces when reducing the intermittent oscillation action by the peak current limit circuit; and abnormal sound, vibration sound are not heard; as previously mentioned, be that the circuit overcurrent protection compensation is similarly diminished to obtain same effect with value and the burst mode (burstmode) of resistance r2.Thus, set resistance value r2＞r3, when switch SW 1 is opened, make it become the resistance value also littler (state that resistance r2 is in parallel with resistance r3) of equal valuely, make the electrorheological that flows through circuit overcurrent protection compensation usefulness resistance big than r2.
But owing to make switch SW 1 short circuit, then becoming underloading must be by external signal.Therefore need extra input terminal and cause cost to rise.
Here can consider following structure: detect the minimizing of the forward voltage of pulse transformer with voltage detecting circuit, the action of forcing to reduce overcurrent sensing circuit by the action of peak current limit circuit begins voltage, so that the little current value of action set point of the common overcurrent sensing circuit of the current ratio that power transistor flows through carries out the action of overcurrent sensing circuit, unlike prior art, apply signal, even intermittent oscillation does not produce abnormal sound yet when underloading from the outside.
When but Switching Power Supply starts, because the initial forward voltage that does not have by the driving winding excitation of pulse transformer, so the peak current limit circuit moves.The peak drain current of power transistor is reduced, can not obtain the electric power of common state, can not start.
Summary of the invention
Switching power circuit of the present invention is to detect underloading by switching power circuit self, when intermittent oscillation is moved, reduces the peak drain current of power transistor, thereby also can start when common load condition.
The invention provides a kind of switching power circuit, the AC voltage of AC power supplies is carried out rectification by rectification circuit be transformed into commutating voltage, the commutating voltage that offers pulse transformer is carried out switch transition by power transistor, this pulse transformer comprises elementary winding, secondary winding and driving winding, when the power transistor with elementary windings in series carries out conduction and cut-off, on described driving winding, encouraged forward voltage, the switching power circuit pair load that is connected with the secondary winding of described pulse transformer provides the load voltage of regulation, it is characterized by switching power circuit comprises: voltage detecting circuit, when detecting intermittent oscillation by the minimizing of the forward voltage of the driving winding excitation of pulse transformer; The peak current limit circuit moves when described voltage detecting circuit detects the forward voltage minimizing; Overcurrent sensing circuit moves according to the peak current limit circuit operation, and the electric current that flows through power transistor is reduced; And input voltage detection circuit, detect commutating voltage, when dropping into, power supply described peak current limit circuit is quit work to becoming.
The present invention also provides a kind of switching power circuit, the AC voltage of AC power supplies is carried out rectification by rectification circuit be transformed into commutating voltage, the commutating voltage that offers pulse transformer is carried out switch transition by power transistor, this pulse transformer comprises elementary winding, secondary winding and driving winding, when the power transistor with elementary windings in series carries out conduction and cut-off, on described driving winding, encouraged forward voltage, the switching power circuit pair load that is connected with the secondary winding of described pulse transformer provides the load voltage of regulation, it is characterized by switching power circuit comprises: voltage detecting circuit, when detecting intermittent oscillation by the minimizing of the forward voltage of the driving winding excitation of pulse transformer; The peak current limit circuit moves when described voltage detecting circuit detects the forward voltage minimizing; Overcurrent sensing circuit moves according to the peak current limit circuit operation, and the electric current that flows through power transistor is reduced; And operation voltage provides circuit, detect commutating voltage, operation voltage is not provided and the peak current limit circuit is failure to actuate to becoming the normal condition when power supply drops into, operation voltage is provided when supply voltage becomes normal condition, for described peak current limit circuit to the peak current limit circuit.
This switching power circuit, the AC voltage of AC power supplies is carried out rectification by rectification circuit, the commutating voltage that offers pulse transformer is carried out switch transition, the load that is connected with the secondary winding of described pulse transformer is provided the load voltage of regulation, comprise: voltage detecting circuit, when detecting intermittent oscillation by the minimizing of the forward voltage of the driving winding excitation of pulse transformer; The peak current limit circuit moves when described voltage detecting circuit detects the forward voltage minimizing; Overcurrent sensing circuit moves by the peak current limit circuit operation, and the electric current that flows through power transistor is reduced; Input voltage detection circuit makes described peak current limit circuit quit work to becoming when power supply drops into the normal condition.
The present invention also proposes a kind of switching power circuit, and described input voltage detection circuit comprises: the 1st and the 2nd voltage detecting resistance is connected in series between the output of described rectification circuit and ground; Electric capacity is connected in parallel with described the 2nd voltage detecting resistance; The 1st voltage detecting transistor, its base stage is connected with the described the 1st and the contact of the 2nd voltage detecting resistance; The 2nd voltage detecting transistor by the 1st voltage detecting transistor controls, makes the peak current limit circuit operation or is failure to actuate.
The present invention also proposes a kind of switching power circuit, the AC voltage of AC power supplies is carried out rectification by rectification circuit, the commutating voltage that offers pulse transformer is carried out switch transition, the load that is connected with the secondary winding of described pulse transformer is provided the load voltage of regulation, comprise: voltage detecting circuit, when detecting intermittent oscillation by the minimizing of the forward voltage of the driving winding excitation of pulse transformer; The peak current limit circuit moves when described voltage detecting circuit detects the forward voltage minimizing; Overcurrent sensing circuit moves by the peak current limit circuit operation, and the electric current that flows through power transistor is reduced; Operation voltage provides circuit, operation voltage is provided for when supply voltage becomes normal condition described peak current limit circuit.
The present invention also proposes a kind of switching power circuit, and described operation voltage provides circuit to comprise: the 1st and the 2nd voltage detecting resistance is connected in series between the output of described rectification circuit and ground; Electric capacity is connected in parallel with described the 2nd voltage detecting resistance, and the operation voltage that offers the peak current limit circuit is the charging voltage of described electric capacity charging.
Description of drawings
Fig. 1 is the block diagram of switching power circuit of the present invention.
Fig. 2 is the circuit diagram of switching power circuit of the present invention.
Fig. 3 is the block diagram of switching power circuit of the present invention.
Fig. 4 is the circuit diagram of switching power circuit of the present invention.
Fig. 5 is the circuit diagram of the switching power circuit of prior art.
Embodiment
Describe embodiments of the present invention in detail with reference to Fig. 1-Fig. 4.
Fig. 1 is abnormal sound and the switching power circuit that can start heard when having prevented the underloading intermittent oscillation of the present invention.Structure division same as the prior art is designated as identical symbol.
The AC voltage of the AC power supplies (not shown) of the elementary winding T1 side of pulse transformer T imposes on each structural detail that constitutes this switching power circuit via rectifier diode D1.
TR2 is a power transistor; make power transistor TR2 conducting or end by control signal; and then the voltage conversion of rectifier diode D1 rectification is exported to the secondary winding of pulse transformer by the elementary winding of the pulse transformer of connecting with power transistor TR2; resistance R 11 is to follow the rising of the input voltage of AC power supplies; being to make the overcurrent protection starting point to change the compensating resistance that compensates, is the 1st compensating resistance that the forward voltage of the driving winding T3 excitation of transformer T is added to the overcurrent sensing circuit 6 of control circuit 5.
In addition, C1 is the electrochemical capacitor that links to each other with the lead-out terminal of secondary winding T2 side, and via this electrochemical capacitor C1, load circuit (not shown) is connected.
The minimizing of the forward voltage of the driving winding T3 excitation of pulse transformer T when voltage detecting circuit 1 detects intermittent oscillation.Peak current limit circuit 3 moves according to the minimizing that voltage detecting circuit 1 detects forward voltage.The overcurrent sensing circuit 6 that is contained in control circuit 5 moves according to the action of peak current limit circuit, reduces the electric current that flows through power transistor.
Input voltage detection circuit 15 was failure to actuate peak current limit circuit 3 before the load voltage that encourages from the secondary winding T2 that starts to pulse transformer T becomes normal voltage.
By said structure, the detection voltage that reduces by voltage detecting circuit 1 detection forward voltage when then moving usually can not be detected, and peak current limit circuit 3 is failure to actuate.So the voltage that overcurrent sensing circuit 6 produces according to flowing through the current value of the 1st compensating resistance R11 moves.
As a result, when moving usually, the electric current that flows through is until obtain maximum output power, and when producing intermittent oscillation thus, power transistor TR2 resembles and flows through very big electric current the prior art, becomes the reason that produces abnormal sound.
But switching power circuit of the present invention detects the minimizing of the forward voltage that drives winding T3 generation by voltage detecting circuit 1 when the voltage intermittent oscillation of holding state.Reduce if detect forward voltage, then peak current limit circuit 3 actions, the action of forcing to reduce overcurrent sensing circuit 6 begins voltage.
Begin voltage by the action that force to reduce overcurrent sensing circuit 6, the electric current that flows through power transistor TR2 little current value when setting than the action of common overcurrent sensing circuit 6 makes overcurrent sensing circuit 6 actions.And reduce the overcurrent protection keying level thus, thereby reduce the peak value of the electric current that flows through power transistor TR2.
In addition, in the charging voltage of the electrochemical capacitor C1 that links to each other with the secondary winding T2 of pulse transformer T during than action usually under the low voltage, overcurrent sensing circuit 6 begins action, therefore, even intermittent oscillation does not make the frequency of oscillation when starting reduce yet, become the frequency of oscillation that is higher than sound wave, do not hear abnormal sound.
Yet, because driving the forward voltage self of winding T3 excitation when starting does not exist, therefore present the state same during underloading with intermittent oscillation, judge that by voltage detecting circuit 1 forward voltage is lower, peak current limit circuit 3 action makes overcurrent sensing circuit 6 with the low-voltage action, has suppressed the peak current of power transistor TR2 and can not start.
But in the switching power circuit of the present invention, input voltage detection circuit 15 was failure to actuate peak current limit circuit 3 before the load voltage that encourages from the secondary winding T2 that starts to pulse transformer T becomes normal voltage.Therefore, overcurrent sensing circuit 6 makes power transistor TR2 flow through common peak current by action usually, can accessiblely start.
Fig. 2 is the circuit diagram of other embodiment of expression switching power circuit of the present invention.
The AC voltage of the AC power supplies (not shown) of the elementary winding T1 side of pulse transformer T imposes on each structural detail that constitutes this switching power circuit via rectifier diode D1.
TR2 is a power transistor; make power transistor TR2 conducting or end by control signal; and then the voltage conversion of rectifier diode D1 rectification is exported to the secondary winding of pulse transformer by the elementary winding of the pulse transformer of connecting with power transistor TR2; resistance R 11 is to follow the rising of the input voltage of AC power supplies; being to make the overcurrent protection starting point to change the compensating resistance that compensates, is the 1st compensating resistance that the forward voltage of the driving winding T3 excitation of transformer T is added to the overcurrent sensing circuit 6 of control circuit 5.
In addition, C1 is the electrochemical capacitor that links to each other with the lead-out terminal of secondary winding T2 side, and via this electrochemical capacitor C1, load circuit (not shown) is connected.
The minimizing of the forward voltage of the driving winding T3 excitation of pulse transformer T when voltage detecting circuit 1 detects intermittent oscillation.Peak current limit circuit 3 moves according to the minimizing that voltage detecting circuit 1 detects forward voltage.The overcurrent sensing circuit 6 that is contained in control circuit 5 moves by the action that makes the peak current limit circuit, reduces the electric current that flows through power transistor.
And peak current limit circuit 3 comprises: by the peak current limit transistor 9 of voltage detecting transistor 7 controls; Series circuit between the collector electrode-emitter Lu Yudi 2 compensating resistance R12 of the described peak current limit transistor 9 in parallel with the 1st compensating resistance R11 of the overcurrent protection of definite power transistor TR2 action beginning voltage.In addition, between the collector electrode of peak current limit transistor 9 and base stage, be connected biasing resistor R16.
And input voltage detection circuit 15 comprises: the 1st voltage detecting resistance R 17 and the 2nd voltage detecting resistance R 18 of connecting between rectifier diode D1 and ground; The capacitor C 12 in parallel with the 2nd voltage detecting resistance R 18; The 1st voltage detecting transistor 10 that its base stage and the 1st voltage detecting resistance R 17 link to each other with the contact of the 2nd voltage detecting resistance R 18; The 2nd supply voltage that links to each other with the 1st voltage detecting transistor 10 and link to each other with the base stage of peak current limit transistor 9 detects transistor 11.
Switching circuit of the present invention control signal by control circuit 5 when common action makes power transistor TR2 carry out conduction and cut-off and produces voltage at the secondary winding T2 of pulse transformer T, and meanwhile the driving winding T3 at pulse transformer T has encouraged forward voltage.
The forward voltage of excitation imposes on resistance R 14 via diode 8 when moving usually, to capacitor C 11 chargings.The charging voltage of capacitor C 11 makes 7 conductings of voltage detecting transistor.Therefore, the bias voltage that imposes on resistance R 12 and biasing resistor R16 is ground connection via the collector electrode-emitter of voltage detecting transistor 7, and peak current limit transistor 9 ends.
Therefore, overcurrent sensing circuit 6 moves according to the voltage that the current value that flows through resistance R 11 produces, and allows the electric current that can obtain maximum output power flow through when moving usually.
When the underloading of holding state etc. and since the control signal power transistor TR2 of control circuit 5 during than work usually deadline elongated, therefore, the forward voltage that drives winding T3 excitation reduces.
Therefore, because forward voltage reduces, diode 8 and also reduced by first both end voltage that detects resistance R 14 and the electric capacity 11 of the second detection resistance R, 15 dividing potential drops is so the base voltage of voltage detecting transistor 7 also reduces.Therefore, voltage detecting transistor 7 ends.
If voltage detecting transistor 7 ends, the end of biasing resistor R16 is disengaged via the state of the collector electrode-grounded emitter of voltage detecting transistor 7 before this.Therefore, the bias voltage that is added in biasing resistor 16 via diode 8 is added to the base stage of peak current limit transistor 9, makes 9 conductings of peak current limit transistor.
9 conductings of peak current limit transistor, then the 2nd compensating resistance R12 becomes state in parallel with the 1st compensating resistance R11.Therefore, the action of overcurrent sensing circuit 6 begins level and descends, and the peak current of power transistor TR2 is flow through in restriction.
Be forced to reduce because the action of overcurrent sensing circuit 6 begins voltage, the electric current that flows through power transistor TR2 little current value when setting than the action of common overcurrent sensing circuit 6 makes overcurrent sensing circuit 6 actions.And reducing the overcurrent keying level thus, the peak value that then flows through the electric current of power transistor TR2 also descends.
In addition, in the charging voltage of the electrochemical capacitor C1 that links to each other with the secondary winding T2 of pulse transformer T1 during than action usually under the low voltage, overcurrent sensing circuit 6 begins action, therefore, even intermittent oscillation does not reduce the frequency of oscillation when starting yet, become the frequency of oscillation that is higher than sound wave, even therefore when underloading intermittent oscillation also move with the quick oscillation frequency, do not hear ' Pi, the abnormal sound of Pi ' sound etc.
As previously mentioned, because driving the forward voltage self of winding T3 excitation when starting does not exist, therefore present the state same during underloading with intermittent oscillation, judge that by voltage detecting circuit 1 forward voltage is lower, peak current limit circuit 3 action makes overcurrent sensing circuit 6 with the low-voltage action, has suppressed the peak current of power transistor TR2 and can not start.
But in the switching power circuit of the present invention, the C12 of input voltage detection circuit 15 made the 1st voltage detecting transistor 10 end before being charged to assigned voltage, therefore the 2nd voltage detecting transistor 11 conductings.11 conductings of the 2nd voltage detecting transistor, then peak current limit transistor 9 is forced to end.
Therefore, the voltage that overcurrent sensing circuit 6 produces according to flowing through the current value of the 1st compensating resistance R11 moves, and allows the electric current that can obtain maximum output power flow through, and can start.
Therefore, if the size of selected the 1st voltage detecting resistance R 17 and voltage charging capacitor C 12 makes the 2nd supply voltage detect transistor 11 and ended before becoming common operate condition, then can start without barrier.
Fig. 3 is the block diagram of expression other embodiment of switching power circuit of the present invention.Compared to Figure 1, except operation voltage generation circuit 16 replacement input voltage detection circuits 15 are set, be identical.
Usually the action of operate condition and light condition is identical with Fig. 1.
Yet being set at when starting, the operation voltage generation circuit 16 in the switching circuit of the present invention can not provide electric current to peak current limit circuit 3, before the load voltage of the secondary winding T2 of pulse transformer T excitation becomes normal voltage, do not produce operation voltage, peak current limit circuit 3 is failure to actuate.Therefore overcurrent sensing circuit 6 is by action usually, and power transistor TR2 can flow through common electric current, can accessiblely start.
Fig. 4 is the circuit diagram of other embodiment of expression switching power circuit of the present invention.
Operation voltage generation circuit 16 comprises: the 1st voltage detecting resistance R 17 and the 2nd voltage detecting resistance R 18 of connecting between rectifier diode D1 and ground; The voltage charging capacitor C 12 in parallel with the 2nd voltage detecting resistance R 18.At the contact of the 1st voltage detecting resistance R 17 and the 2nd voltage detecting resistance R 18, connect the 2nd resistance R 12 that links to each other with peak current limit transistor 9.
Because it is lower when starting by the forward voltage that drives winding T3 excitation.Therefore when underloading and intermittent oscillation present same minimizing, it is lower to detect forward voltage by voltage detecting circuit 1, peak current limit circuit 3 action makes overcurrent sensing circuit 6 with the low voltage action, has suppressed the peak current of power transistor TR2 and can not start.
But the operation voltage generation circuit 16 in the switching circuit of the present invention provides sufficient operation voltage can not for peak current limit transistor 9 when capacitor C 11 chargings, thereby is failure to actuate.
Therefore, the voltage that overcurrent sensing circuit 6 produces according to flowing through the current value of compensating resistance R11 moves, and allows the electric current that can obtain maximum output power flow through when moving usually, can start.
Therefore, if the size of selected the 1st voltage detecting resistance R 17 and capacitor C 12 was failure to actuate peak current limit transistor 9 before becoming common operate condition, then can start without barrier.
Constituting of switching power circuit of the present invention: the minimizing of forward voltage when detecting intermittent oscillation by voltage detecting circuit, the action that makes the peak current limit circuit operation and force to reduce overcurrent sensing circuit begins voltage, the electric current that flows through power transistor is the less current value when setting than the action of common overcurrent sensing circuit, makes the overcurrent sensing circuit action.Owing to force between the normal condition peak current limit circuit is failure to actuate to becoming at starting state, can start without barrier.
Claims (4)
1. switching power circuit, the AC voltage of AC power supplies is carried out rectification by rectification circuit be transformed into commutating voltage, the commutating voltage that offers pulse transformer is carried out switch transition by power transistor, this pulse transformer comprises elementary winding, secondary winding and driving winding, when the power transistor with elementary windings in series carries out conduction and cut-off, on described driving winding, encouraged forward voltage, the switching power circuit pair load that is connected with the secondary winding of described pulse transformer provides the load voltage of regulation, it is characterized by switching power circuit and comprises:
Voltage detecting circuit, when detecting intermittent oscillation by the minimizing of the forward voltage of the driving winding excitation of pulse transformer;
The peak current limit circuit moves when described voltage detecting circuit detects the forward voltage minimizing;
Overcurrent sensing circuit moves according to the peak current limit circuit operation, and the electric current that flows through power transistor is reduced; And
Input voltage detection circuit detects commutating voltage, to becoming described peak current limit circuit is quit work when power supply drops into.
2. switching power circuit as claimed in claim 1, described input voltage detection circuit comprises:
The the 1st and the 2nd voltage detecting resistance is connected in series between the output of described rectification circuit and ground;
Electric capacity is connected in parallel with described the 2nd voltage detecting resistance;
The 1st voltage detecting transistor, its base stage is connected with the described the 1st and the contact of the 2nd voltage detecting resistance;
The 2nd voltage detecting transistor by the 1st voltage detecting transistor controls, makes the peak current limit circuit operation or is failure to actuate.
3. switching power circuit, the AC voltage of AC power supplies is carried out rectification by rectification circuit be transformed into commutating voltage, the commutating voltage that offers pulse transformer is carried out switch transition by power transistor, this pulse transformer comprises elementary winding, secondary winding and driving winding, when the power transistor with elementary windings in series carries out conduction and cut-off, on described driving winding, encouraged forward voltage, the switching power circuit pair load that is connected with the secondary winding of described pulse transformer provides the load voltage of regulation, it is characterized by switching power circuit and comprises:
Voltage detecting circuit, when detecting intermittent oscillation by the minimizing of the forward voltage of the driving winding excitation of pulse transformer;
The peak current limit circuit moves when described voltage detecting circuit detects the forward voltage minimizing;
Overcurrent sensing circuit moves according to the peak current limit circuit operation, and the electric current that flows through power transistor is reduced; And
Operation voltage provides circuit, detect commutating voltage, operation voltage is not provided and the peak current limit circuit is failure to actuate to becoming the normal condition when power supply drops into, operation voltage is provided when supply voltage becomes normal condition, for described peak current limit circuit to the peak current limit circuit.
4. switching power circuit as claimed in claim 3, described operation voltage provides circuit to comprise:
The the 1st and the 2nd voltage detecting resistance is connected in series between the output of described rectification circuit and ground;
Electric capacity is connected in parallel with described the 2nd voltage detecting resistance,
It is characterized by, the operation voltage that offers the peak current limit circuit is the charging voltage of described electric capacity charging.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP029854/03 | 2003-02-06 | ||
| JP029854/2003 | 2003-02-06 | ||
| JP2003029854A JP4307097B2 (en) | 2003-02-06 | 2003-02-06 | Switching power supply circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1520016A CN1520016A (en) | 2004-08-11 |
| CN1333513C true CN1333513C (en) | 2007-08-22 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100032579A Expired - Fee Related CN1333513C (en) | 2003-02-06 | 2004-02-03 | Switching power source circuit |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP4307097B2 (en) |
| CN (1) | CN1333513C (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7245510B2 (en) * | 2005-07-07 | 2007-07-17 | Power Integrations, Inc. | Method and apparatus for conditional response to a fault condition in a switching power supply |
| US20110273805A1 (en) * | 2010-05-06 | 2011-11-10 | Nguyen Don J | Hdmi cable connect apparatus and method |
| JP5608544B2 (en) * | 2010-12-22 | 2014-10-15 | ルネサスエレクトロニクス株式会社 | Output circuit |
| CN111884512A (en) * | 2020-03-18 | 2020-11-03 | 深圳市航嘉驰源电气股份有限公司 | Switching power supply, power adapter and charger |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0799773A (en) * | 1993-09-27 | 1995-04-11 | Tec Corp | Switching power source unit |
| JPH0923644A (en) * | 1995-07-04 | 1997-01-21 | Matsushita Electric Ind Co Ltd | Switching power supply |
| JP2000134946A (en) * | 1998-10-27 | 2000-05-12 | Canon Inc | High voltage power supply |
-
2003
- 2003-02-06 JP JP2003029854A patent/JP4307097B2/en not_active Expired - Fee Related
-
2004
- 2004-02-03 CN CNB2004100032579A patent/CN1333513C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0799773A (en) * | 1993-09-27 | 1995-04-11 | Tec Corp | Switching power source unit |
| JPH0923644A (en) * | 1995-07-04 | 1997-01-21 | Matsushita Electric Ind Co Ltd | Switching power supply |
| JP2000134946A (en) * | 1998-10-27 | 2000-05-12 | Canon Inc | High voltage power supply |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4307097B2 (en) | 2009-08-05 |
| JP2004242438A (en) | 2004-08-26 |
| CN1520016A (en) | 2004-08-11 |
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