CN1333514C - Switching power source circuit - Google Patents
Switching power source circuit Download PDFInfo
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- CN1333514C CN1333514C CNB2004100032583A CN200410003258A CN1333514C CN 1333514 C CN1333514 C CN 1333514C CN B2004100032583 A CNB2004100032583 A CN B2004100032583A CN 200410003258 A CN200410003258 A CN 200410003258A CN 1333514 C CN1333514 C CN 1333514C
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- voltage
- circuit
- resistance
- current limit
- peak current
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Abstract
To detect intermittent oscillation operation with a light load by a switching power supply circuit itself, and to reduce the peak drain current of a power transistor during intermittent oscillation operation. The voltage detecting circuit 1 detects the voltage decrease in the forward direction of a drive coil. A peak current limit circuit 3 is operated by decreasing the detected forward voltage. An overcurrent detecting circuit 6 operates when the peak current limit circuit is operated, and reduces the current flowing a power transistor TR2. The decrease in the forward voltage is detected with the voltage detecting circuit at voltage intermittent oscillation, and the peak current limit circuit is made to operate to forcedly decrease the operation start voltage of the overcurrent detecting circuit. The overcurrent detecting circuit is operated at the value of current flowing the power transistor which is less than the normal operation setting of the overcurrent detecting circuit.
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. 3 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 the overcurrent protection starting point 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 the circuit overcurrent protection in the control system 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.
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.
The switching power circuit that the present invention proposes carries out rectification with the AC voltage of AC power supplies, its commutating voltage is offered pulse transformer to carry out switch transition, the load that is connected with the secondary winding of described pulse transformer is provided the load voltage of regulation, the pulse transformer of described switching power circuit comprises elementary winding, secondary winding and driving winding, when the power transistor with described elementary windings in series carries out conduction and cut-off, on described driving winding, encouraged forward voltage, 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.The minimizing of the forward voltage during intermittent oscillation is detected by described voltage detecting circuit, the action that makes the peak current limit circuit operation and force to reduce overcurrent sensing circuit begins voltage, and the electric current that flows through power transistor little current value when setting than the action of common overcurrent sensing circuit makes the overcurrent sensing circuit action.
The present invention proposes a kind of switching power circuit in addition, and described input voltage detection circuit comprises: the voltage detecting transistor; The 1st detects resistance and the 2nd detection resistance, is connected with the transistorized base stage of this voltage detecting and is applied in forward voltage; Electric capacity charges by being applied to the 1st forward voltage that detects resistance.The forward voltage that when moving usually described driving winding is obtained detects resistance with the described the 1st and the 2nd resistance ratio that detects resistance carries out dividing potential drop, magnitude of voltage (the 2nd detects the resistance both end voltage) according to dividing potential drop makes the voltage detecting transistor turns, the peak current limit circuit is failure to actuate, and during intermittent oscillation since the forward voltage that described driving winding obtains reduce, then the 1st the 2nd voltage that detects the resistance two ends that detects resistance and the 2nd detection electric resistance partial pressure also reduces and described voltage detecting transistor is ended, and makes the peak current limit circuit operation.
The present invention also proposes a kind of switching power circuit, and described peak current limit circuit comprises: the peak current limit transistor, by described voltage detecting transistor controls; The series circuit of the transistorized collector electrode of described peak current limit-emitter Lu Yudi 2 compensating resistances, the 1st compensating resistance that begins voltage with the overcurrent protection action of the described power transistor of compensation is in parallel.Described voltage detecting transistor is ended, thereby make the peak current limit circuit operation make described the 1st compensating resistance in parallel with the 2nd compensating resistance.
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 circuit diagram of the switching power circuit of prior art.
Embodiment
Describe embodiments of the present invention in detail with reference to Fig. 1 and Fig. 2.
Fig. 1 is a switching power circuit of hearing abnormal sound 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.
Make TR2 conducting or end by control signal; thereby the elementary winding of pulse transformer by series connection is with it changed the voltage of rectifier diode D1 rectification; export the secondary winding of pulse transformer to; 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 this electrochemical capacitor C1 links to each other with load circuit (not shown).
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.
By said structure, then action can not be detected by the detection voltage that voltage detecting circuit 1 detects the forward voltage minimizing usually, and peak current limit circuit 3 is failure to actuate.Therefore overcurrent sensing circuit 6 moves according to the current value that flows through the 1st compensating resistance R11 with by the voltage that the current sense resistor of power transistor TR2 etc. obtains.
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 make 3 actions of peak current limit circuit, 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 reduce the frequency of oscillation when starting yet, become the frequency of oscillation that is higher than sound wave, do not hear abnormal sound.
Fig. 2 is the circuit diagram of other embodiment of expression switching power circuit of the present invention.
With aforementioned same, the AC voltage of the AC power supplies (not shown) of the elementary winding T1 side of pulse transformer T is via after-applied each structural detail that constitutes this switching power circuit of giving of rectifier diode D1 rectification.
Make TR2 conducting or end by control signal; thereby the elementary winding of pulse transformer by series connection is with it changed the voltage of rectifier diode D1 rectification; export the secondary winding of pulse transformer to; 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 side, and this electrochemical capacitor C1 links to each other with load circuit (not shown).
Voltage detecting circuit 1 comprises: voltage detecting transistor 7; The forward voltage that links to each other with the base stage of voltage detecting transistor 7, the driving winding T3 of pulse transformer T is produced the 1st detects resistance R 14 and the 2nd detection resistance R 15 via what diode 8 applied; And the capacitor C 11 that is connected the 2nd detection resistance R 15 two ends.
Being connected the 2nd capacitor C 11 that detects resistance R 15 two ends removes noise contribution and will also have the voltage that the 2nd detection resistance R 15 two ends are produced to have the effect of time constant from the voltage integrating meter of the 1st detection resistance R 14.
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.
If the resistance value r2 of the resistance value r1 of the 1st compensating resistance R11 and the 2nd compensating resistance R12 satisfies: r1＞r2.Specifically, making r1 and the ratio of r2 is about 10: 1.
Switching power 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 during common the action, according to detecting the voltage ratio of resistance R 14 with R15 capacitor C 11 is charged.The charging voltage of capacitor C 11 makes 7 conductings of voltage detecting transistor.Therefore, the bias voltage that imposes on compensating resistance R12 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 compensating resistance R11 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 power transistor TR2 during than work usually deadline elongated, therefore, the forward voltage that drives winding T3 excitation reduces.
Therefore, the both end voltage that detects the capacitor C 11 of resistance R 14 via diode 8 and first reduces, so the base potential voltage of voltage detecting transistor 7 reduces.Therefore, voltage detecting transistor 7 ends.
Voltage detecting transistor 7 ends, and then 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 R16 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 compensating resistance equivalence diminishes and the detection electric current essence that flows into overcurrent sensing circuit 6 becomes big, and 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 common action 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 T 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.
Constituting of switching power circuit of the present invention: drive the minimizing of the forward voltage of winding generation 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.Unlike prior art, apply signal, even intermittent oscillation does not produce abnormal sound yet when underloading from the outside.
Claims (3)
1. switching power circuit, the AC voltage of AC power supplies is carried out rectification, its commutating voltage is offered pulse transformer to carry out switch transition, the load that is connected with the secondary winding of described pulse transformer is provided the load voltage of regulation, the pulse transformer of described switching power circuit comprises elementary winding, secondary winding and driving winding, when the power transistor with described elementary windings in series carries out conduction and cut-off, encouraged forward voltage on described driving winding, this switching power circuit has:
Voltage detecting circuit detects because the intermittent oscillation during underloading and 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,
It is characterized by, the minimizing of the forward voltage that produces during intermittent oscillation is detected by described voltage detecting circuit, the action that makes the peak current limit circuit operation and force to reduce overcurrent sensing circuit begins voltage, and the electric current that flows through power transistor little current value when setting than the action of common overcurrent sensing circuit makes the overcurrent sensing circuit action.
2. switching power circuit as claimed in claim 1 is characterized by, and described voltage detecting circuit comprises:
The voltage detecting transistor;
The 1st detects resistance, is connected with the transistorized base stage of this voltage detecting and is applied in forward voltage;
Electric capacity charges by being applied to the 1st forward voltage that detects resistance;
The 2nd detects resistance, with described the 1st detection resistance the forward voltage that applies is carried out dividing potential drop,
The forward voltage that when moving usually described driving winding is obtained detects resistance with the described the 1st and the 2nd resistance ratio that detects resistance carries out dividing potential drop, magnitude of voltage according to dividing potential drop makes the voltage detecting transistor turns, the peak current limit circuit is failure to actuate, and during the underloading intermittent oscillation since the forward voltage that described driving winding obtains reduce, then detect resistance and carry out the voltage minimizing that the 2nd of dividing potential drop detects the resistance two ends with the 1st, thereby make described voltage detecting transistor end, make the peak current limit circuit operation.
3. switching power circuit as claimed in claim 2 is characterized by, and described peak current limit circuit comprises:
The peak current limit transistor is by described voltage detecting transistor controls;
The series circuit of the transistorized collector electrode of described peak current limit-emitter Lu Yudi 2 compensating resistances, the 1st compensating resistance that begins voltage with the overcurrent protection action of the described power transistor of compensation is in parallel,
Described voltage detecting transistor is ended, thereby make the peak current limit circuit operation make described the 1st compensating resistance in parallel with the 2nd compensating resistance.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP029855/2003 | 2003-02-06 | ||
| JP2003029855A JP2004242439A (en) | 2003-02-06 | 2003-02-06 | Switching power supply circuit |
| JP029855/03 | 2003-02-06 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1520017A CN1520017A (en) | 2004-08-11 |
| CN1333514C true CN1333514C (en) | 2007-08-22 |
Family
ID=32956917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004100032583A Expired - Fee Related CN1333514C (en) | 2003-02-06 | 2004-02-03 | Switching power source circuit |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2004242439A (en) |
| CN (1) | CN1333514C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010288334A (en) | 2009-06-09 | 2010-12-24 | Panasonic Corp | Switching power supply apparatus and semiconductor device |
| JP5341627B2 (en) * | 2009-06-11 | 2013-11-13 | パナソニック株式会社 | Semiconductor device and switching power supply device |
| CN112531650A (en) * | 2020-12-07 | 2021-03-19 | 华羿微电子股份有限公司 | From power MOSFET who takes short-circuit protection |
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 JP2003029855A patent/JP2004242439A/en active Pending
-
2004
- 2004-02-03 CN CNB2004100032583A patent/CN1333514C/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 |
|---|---|
| JP2004242439A (en) | 2004-08-26 |
| CN1520017A (en) | 2004-08-11 |
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Granted publication date: 20070822 Termination date: 20220203 |