CN1225832C - Switching power supply - Google Patents
Switching power supply Download PDFInfo
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- CN1225832C CN1225832C CN 03114191 CN03114191A CN1225832C CN 1225832 C CN1225832 C CN 1225832C CN 03114191 CN03114191 CN 03114191 CN 03114191 A CN03114191 A CN 03114191A CN 1225832 C CN1225832 C CN 1225832C
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Abstract
The present invention relates to a switching power supply which comprises an input rectification filter circuit, a self-excited oscillation circuit, a surge voltage absorption circuit, a transformer, a discharging loop, a short-circuit protection circuit, a secondary rectification filter circuit, a secondary voltage stabilization circuit and a feedback circuit, wherein the surge voltage absorption circuit is connected in parallel with both ends of the primary winding TIA of the transformer; feedback control signals are input into the self-excited oscillation circuit by the feedback circuit mainly through a pair of photoelectric couplers U1A and U1B and for controlling the switching of a switching transistor; both ends of a charging capacitor C4, which are used for providing switching-on voltage for the switching transistor, are connected in parallel with the discharging loop mainly comprising a triode. Further, the switching power supply is provided with the short-circuit protection circuit for preventing the charging capacitor (C4) from accelerated charging when the output of the switching power supply has a short circuit. The switching power supply does not need a special pulse width integration controller, and has the advantages of small starting and continuous operation current and simple circuit. The switching power supply realizes constant voltage output and short-circuit protection.
Description
Technical field
The present invention relates to a kind of Switching Power Supply, especially a kind of have one-period ground and switch through the switching type power supply that is applied to the primary winding voltage.This Switching Power Supply is allowed very wide input voltage range, adapts to the voltage request of global different regions, is suitable for general DC power supply or charge power supply, is specially adapted to the charge power supply of cordless telephone, and the power supply of MD, CD and electronics hand account etc.
Background technology
General Switching Power Supply all is to adopt special-purpose pulsewidth integrated manipulator, for example " novel switched power supply practical technique " the 62nd, 63 page of Switching Power Supply of being introduced in the Electronic Industry Press---use pulsewidth integrated manipulator UC3842, it is the integrated circuit of applied current control (Current Mode Control) PWM.The deficiency of its existence is: 1, need special-purpose pulsewidth integrated manipulator, cost of manufacture height; 2, need bigger start and ongoing operation electric current; 3, the peripheral components requirement is more, is unfavorable for microminiaturization.
For this reason, it is that CN2523108, denomination of invention are the utility model patent of " a kind of self-oscillation flyback switched mode power supply " that the present inventor has proposed a kind of publication number, this patent has solved the deficiency that above-mentioned prior art exists, and does not need special-purpose pulsewidth integrated manipulator, start and the ongoing operation electric current is little, circuit is simple.But still also have following technical defective in actual applications: 1, when output short-circuit, output services frequency height, power are big, damage power device easily.2, when underload and high voltage when input, too fast switching frequency also usually can cause damage to power device.Particularly switching transistor is caused damage, cause reduce greatly the useful life of switching transistor, have a strong impact on the service behaviour of Switching Power Supply.
Summary of the invention
Purpose of the present invention is intended to overcome above-mentioned the deficiencies in the prior art, proposes a kind of Switching Power Supply with short-circuit protection.
Further, a time purpose of the present invention is to propose a kind ofly to prevent when underload and high voltage when importing that too fast switching frequency causes damage to switching transistor.
Realize the technical scheme of above-mentioned purpose: a kind of Switching Power Supply, comprise input rectifying filter circuit, transformer, secondary commutation filter circuit, self-maintained circuit and short-circuit protection circuit, wherein:
Transformer is made up of the first elementary winding, the second elementary winding and secondary winding;
Self-maintained circuit comprises charging circuit, voltage feedback circuit, first switching transistor, second switch transistor and the 3rd diode; Charging circuit by first resistance, first electric capacity, the 3rd resistance is in sequential series forms, voltage feedback circuit by the 4th resistance, the 6th resistance, the 5th resistance is in sequential series forms;
The voltage output of input rectifying filter circuit connects an end of the first elementary winding, this output also connects an end of the second elementary winding through charging circuit, the elementary 0V end of another termination of the second elementary winding, the other end of the first elementary winding is connected in series the second switch transistor drain in turn, connect elementary 0V end behind source electrode and the 5th resistance, the anode of transistorized grid of second switch and the 3rd diode, first electric capacity is connected with the link of first resistance, the negative electrode of the 3rd diode connects the collection utmost point of first switching transistor, the emitter-base bandgap grading of first switching transistor connects elementary 0V end, the end that the 5th resistance does not meet elementary 0V connects the base stage of first switching transistor and an end of the 4th resistance through the 6th resistance, another termination second elementary winding of the 4th resistance and the link of charging circuit, the voltage output of secondary winding connects the secondary commutation filter circuit;
Short-circuit protection circuit comprises the 13 resistance, the 6th electric capacity and first diode; one termination, first electric capacity of the 13 resistance and the link of first resistance; the negative electrode of another termination first diode of the 13 resistance and an end of the 6th electric capacity; the anode of first diode connects elementary 0V end, another termination the 3rd resistance of the 6th electric capacity and the link of first electric capacity.
Can and be connected to discharge circuit at the described first electric capacity two ends, first electric capacity and discharge circuit constitute discharge loop.
Described discharge circuit can comprise the 3rd switching transistor and first current-limiting resistance, the collection utmost point serial connection of the emitter-base bandgap grading of the 3rd switching transistor, first electric capacity, first current-limiting resistance and the 3rd switching transistor constitutes discharge loop, and the base stage of the 3rd switching transistor connects elementary 0V end through the 14 resistance.
Further, described discharge loop is in series with unidirectional conducting diode, and the emitter-base bandgap grading of the 3rd switching transistor connects the 3rd switching transistor collection utmost point through unidirectional conducting diode, first electric capacity and first current-limiting resistance and constitutes discharge loop.
Two ends at the described transformer first elementary winding also can and be connected to surge voltage absorbing circuit.
The output of described secondary commutation filter circuit is provided with feedback control circuit, and feedback control circuit is made up of first photoelectrical coupler, second photoelectrical coupler, the 7th resistance, secondary voltage stabilizing circuit, the 5th electric capacity, second diode, second resistance and second electric capacity; The output of secondary commutation filter circuit connects secondary voltage stabilizing circuit through first photoelectrical coupler, the 7th resistance; The anode of second diode connects the link of the second elementary winding and charging circuit; The elementary 0V end of one termination of the 5th electric capacity, the other end is connected with the negative electrode of second diode, an end of second photoelectrical coupler; The other end of second photoelectrical coupler is connected with the link of the 4th resistance with base stage, the 6th resistance of first switching transistor through second resistance; Second electric capacity is attempted by between the base stage and emitter-base bandgap grading of first switching transistor, makes High frequency filter and uses.
Described secondary voltage stabilizing circuit comprises the constant voltage circuit that is made of the 9th resistance, the tenth resistance, the 3rd electric capacity, the 11 resistance, the 12 resistance and voltage-stabiliser tube, the output of one terminates secondary current rectifying and wave filtering circuit of the 9th resistance and the 11 resistance, the negative electrode of another termination voltage-stabiliser tube of the 9th resistance, the control utmost point of another termination voltage-stabiliser tube of the 11 resistance and an end of the 12 resistance, the anode of another termination voltage-stabiliser tube of the 12 resistance, the tenth resistance of series connection and the 3rd electric capacity are attempted by between the negative electrode and the control utmost point of voltage-stabiliser tube.
Described secondary voltage stabilizing circuit also comprises the current-limiting control circuit that is made of triode, the 8th resistance, the 4th electric capacity and second current-limiting resistance, the collection utmost point of triode connects the negative electrode of voltage-stabiliser tube, base stage connects the anode of voltage-stabiliser tube and an end of second current-limiting resistance through the 8th resistance, the emitter-base bandgap grading of another termination triode of second current-limiting resistance, the 4th electric capacity are connected in parallel between the emitter-base bandgap grading and base stage of triode.
Described input rectifying filter circuit can adopt such structure: comprise diode bridge rectifier circuit and LC low pass filter, the output of diode bridge rectifier circuit connects the LC low pass filter, and the output of LC low pass filter connects the first elementary winding.
Described input rectifying filter circuit also can adopt such structure: comprise thermistor, fuse, first filter capacitor, inductor, diode rectifier bridge and second filter capacitor, connect inductor after thermistor and the fuse series connection, the input of inductor also connects first filter capacitor, and the output of inductor is after the diode rectifier bridge rectification and connect second filter capacitor.
Switching Power Supply according to the such scheme making, press the work of flyback converter principle, when switching transistor is switched on, electric current flows through transformer and it is magnetized, when switching transistor is turned off, magnetic energy will be by transformer coupled to secondary, and secondary control circuit control is output as constant voltage source or constant-current supply.Its tangible technique effect is: 1, by short-circuit protection circuit is set, output services frequency and power diminish when making short circuit, are not easy to damage power device, and is safe and reliable.2, feedback control circuit and output voltage stabilizing circuit are set, can both provide overvoltage and overcurrent and protect timely and regulate.3, by at the first electric capacity two ends and connect discharge circuit, make first electric capacity and discharge circuit constitute discharge loop.Before taking place feasible next cycle of oscillation, first electric capacity will charge to the transistorized conducting voltage of second switch through resistance, thereby produce a time of delay, when preventing underload and the infringement that the second switch transistor is caused of high voltage too fast switching frequency of when input, avoid the transistorized superheating phenomenon of second switch, improve second switch transistorized useful life, thereby improve the service behaviour of whole Switching Power Supply.4, do not have complicated circuit, it is very little that static state is kept operating current, only needs very little start and ongoing operation electric current, thereby, the less miniaturized component of optional diligent loss-rate.6, this Switching Power Supply active and passive device of very few number, therefore very cost saving.Simultaneously, because number of devices seldom, so be easy to be made into small-sized portable Switching Power Supply, is specially adapted to the power supply of charge power supply and MD, CD and the electronics hand account etc. of cordless telephone.7, the very wide input voltage range of design tolerable of entire circuit is to adapt to the voltage request of global different regions.In sum, the present invention is a kind of have short-circuit protection, small-sized and cheap Switching Power Supply.
Description of drawings
Fig. 1 is a circuit diagram of the present invention.
Fig. 2 is another kind of input rectifying filter circuit figure.
Embodiment
Embodiment: with reference to Fig. 1; a kind of Switching Power Supply comprises input rectifying filter circuit, surge voltage absorbing circuit, transformer, self-maintained circuit, discharge loop, short-circuit protection circuit, secondary commutation filter circuit, secondary voltage stabilizing circuit and feedback control circuit.
Constitute the input rectifying filter circuit by R1, D1-D4, C1, L1 and C2.By the surge voltage absorbing circuit that R3, C3, R4, D5 constitute, surge voltage absorbing circuit is attempted by the two ends of primary winding T1A.Form transformer T by elementary winding T1A, elementary winding T1B and secondary winding T1C.
Self-maintained circuit comprises by resistance R 2, capacitor C 4, the charging circuit that resistance R 7 is composed in series, by resistance R 8, R10, the voltage feedback circuit that R9 is in series, primary winding T1B, switching transistor Q2, Q1 and diode D8, the elementary 0V end of the termination of elementary winding T1B, the other end is through resistance R 7, capacitor C 4, resistance R 2 connects the output of input rectifying filter circuit, switching transistor Q2 is the MOS field-effect transistor, the input of switching transistor Q2 and capacitor C 4, the anode of resistance R 2 and D8 also connects, connect elementary 0V end after the output of elementary winding T1A serial connection switching transistor Q2 and the resistance R 9, the negative electrode of D8 connects the collection utmost point of transistor Q1, the emitter-base bandgap grading of transistor Q1 connects elementary 0V end, between the base stage of transistor Q1 and the emitter-base bandgap grading and connect capacitor C 5, the base stage of transistor Q1 and connecting resistance R8, R10, the other end of resistance R 8 also connects the anode of elementary winding T1B and D7, the other end of resistance R 10 connects elementary 0V end through resistance R 9
At capacitor C 4 two ends and be connected to discharge loop, discharge circuit comprises that resistance R 20, current-limiting resistance R6 and transistor Q4 form, and the emitter-base bandgap grading of transistor Q4 connects the collection utmost point through C4 and current-limiting resistance R6 and forms discharge loop, and the base stage of transistor Q4 connects elementary 0V end through resistance R 20.
Short-circuit protection circuit comprises resistance R 19, capacitor C 13 and diode D6; the grid of one termination switching transistor Q2 of resistance R 19; the negative electrode of another terminating diode D6 of resistance R 19 and an end of capacitor C 13, the anode of diode D6 connect elementary 0V end, and the other end of C13 also meets R7 and C4.
Constitute the secondary commutation filter circuit by D9, C6 and C7.The output of secondary commutation filter circuit is provided with feedback control circuit, feedback control circuit is made up of photoelectrical coupler U1A, U1B, resistance R 11, secondary voltage stabilizing circuit, capacitor C 12, diode D7, resistance R 5 and capacitor C 5, the output of secondary commutation filter circuit connects secondary voltage stabilizing circuit through photoelectrical coupler U1A, resistance R 11, the elementary 0V end of the termination of charging capacitor C12, the end of the negative electrode of the other end and D7 and photoelectrical coupler U1B also connects, and the other end of photoelectrical coupler U1B is through resistance R 5 and connect base stage and the resistance R 10 of transistor Q1.
Secondary voltage stabilizing circuit comprises constant voltage circuit and current-limiting control circuit, constant voltage circuit is made up of R14, R15, C8, R16, R18 and U2, the end of R14 and R16 also connects the output of secondary commutation filter circuit, the negative electrode of another termination voltage-stabiliser tube U2 of R14, the other end of R16 also connects the control utmost point and the resistance R 18 of voltage-stabiliser tube U2, the anode of another termination voltage-stabiliser tube U2 of resistance R 18, the R15 of series connection and C8 are attempted by between the negative electrode and the control utmost point of voltage-stabiliser tube U2.Current-limiting control circuit comprises triode Q3, resistance R 13, capacitor C 10 and current-limiting resistance R12, the collection utmost point of triode Q3 connects the negative electrode of voltage-stabiliser tube U2, base stage is through resistance R 13 and connect the anode of voltage-stabiliser tube U2 and the end of current-limiting resistance R12, the emitter-base bandgap grading of another termination triode Q3 of current-limiting resistance R12, capacitor C 10 is connected in parallel on emitter-base bandgap grading and the base stage two ends of triode Q3, and the output of secondary commutation filter circuit is in parallel with the emitter-base bandgap grading of Q3 after C11 connects elementary 0V end through capacitor C 7.
The output of secondary voltage stabilizing circuit is provided with filter circuit; filter circuit constitutes a low pass LC filter by L2, C9, and its resonance frequency can be reduced to the ripple of output current very low far below switching frequency; voltage-stabiliser tube Z1 is as output over-voltage protection, to prevent too high output voltage.
The course of work: receive civil power when this Switching Power Supply and get on, capacitor C1 and C2 are charged to the peak value of supply voltage immediately, supply voltage is through the high resistant resistance R 2 of series connection, C4,7 pairs of elementary winding T1B chargings of low-resistance resistance R, voltage on C4 rises to the conducting voltage of Q2, Q2 promptly begins conducting, positive feedback voltage along with elementary winding T1B, switching transistor Q2 enters the deep layer conducting, the electric current of primary winding T1A begins to rise, this electric current flow through simultaneously Q2 and R9, voltage on R9 rises and makes the Q1 conducting, voltage on the Q2 grid reduces and makes the output current of switching transistor Q2 reduce, secondary winding T1C output voltage reduces, thereby makes output voltage maintain a steady state value.Simultaneously, elementary winding T1B produces a negative voltage immediately and makes Q2 quicken to end.In this process, the energy that is stored among the transformer T begins to be stored into C7 through secondary winding T1C, D9, C6, and the energy in transformer T discharges and finishes, and switching transistor Q2 is conducting again more again, finishes a cycle of oscillation.When output voltage was higher than the partial pressure value that is set by R16 and R18, the U2 cathode voltage descended, and the electric current of U1A and U1B can increase.At this moment, the bias voltage that the electric current of U1B produces on resistance R 10 increases, and makes Q1 do sth. in advance conducting, and the ON time of switching transistor Q2 reduces thereupon, and final, output voltage can be adjusted on the predefined numerical value of the voltage divider of being made up of R16 and R18 automatically.When load current very little, voltage can maintain this preset value, if load current constantly increases, the voltage of R12 can be followed rising, when the voltage on the R12 is raised to set point, Q3 is conducting immediately, the electric current of photoelectrical coupler U1A, U1B increases, and Q1 does sth. in advance conducting, and the ON time of switching tube Q2 also reduces thereupon, the energy that is stored in transformer also reduces, the output voltage of secondary winding T1C thereby reduction.After output voltage reduced, therefore output current also reduced, and ultimate current can maintain near the preset value.At this moment, this Switching Power Supply is operated in constant current state, and constant current output is provided.
In above-mentioned adjustment process, when making the output current minimizing of switching transistor Q2 whenever the minimizing of the voltage on the Q2 grid, elementary winding T1B flyback immediately produces a negative voltage, and this negative voltage makes Q2 quicken to end on the one hand; On the other hand, under the negative voltage effect when elementary winding T1B flyback, triode Q4 conducting, the discharge loop discharge that charging capacitor C4 constitutes through the collection utmost point and emitter-base bandgap grading, the diode D10 of resistance R 6, triode Q4, before taking place feasible next cycle of oscillation, C4 will charge to the conducting voltage of Q2 through R2, thereby produces a time of delay, when preventing underload and high voltage too fast switching frequency of when input switching transistor is caused damage.
In the charging process of capacitor C 4,, provide another path to make the C4 charging by accelerated charging resistance R 19.Because normal operating frequency is by the voltage decision of accelerated charging resistance R 19 and C13; when output short-circuit, the voltage at T1C two ends is very little, thereby the voltage of the voltage at T1B two ends and C13 becomes very little; output frequency and power diminish, and realize short-circuit protection function by C13, D10 and R19.
Switching Power Supply changes the inversion frequency of switching transistor Q2 by the function of load.Its operating frequency is approximately by 50K to 200KHZ, and operating frequency is the highest when underload maximum input voltage; On the contrary, frequency is minimum when maximum load and minimum input voltage.
Further, several possible replacement schemes in the circuit: 1) if the numerical value of C4 is not too big, the emitter-base bandgap grading of transistor Q4 and collection extremely can reverse grafts, and the transistor Q4 behind the reverse graft is operated in the reversal connection state of the emitter-base bandgap grading and the collection utmost point, and the sense of current is constant, can save D10.2) D10 can be connected on the also contact of R7, D7 and R8.3) littler if discharging current requires, in addition the D10 of discharge circuit can be changed into R6 also can, this moment, the current amplification factor of Q4 became about 1.4) the serial connection position of R7 and C4 is interchangeable.5) value of R5, R6 and C12 can be zero (C12 disconnection).6) less because of the relative R2 of R19, R2 also can be connected on the also contact of R19 and C13.7) voltage stabilizing circuit in the secondary control circuit (R14, R15, C8, R16, R18 and U2) can be replaced by single voltage-stabiliser tube, and the negative electrode of voltage-stabiliser tube is connected on the collection utmost point of Q3, and the anode of voltage-stabiliser tube is connected on the 0V end of output, the i.e. negative pole of capacitor C 9.In addition, a termination D6 negative electrode and the R19 of C13, the other end of C13 can be connected on the also contact of T1B, R7, R8.8) in feedback control circuit, the R5 of serial connection, U1B can transpositions.9) voltage stabilizing circuit on the secondary control circuit (the also contact of U1A, R14 and R16) can directly connect on the also contact of C6, D9, C7.
Resistance R 1 in Fig. 1 current rectifying and wave filtering circuit can be fuse Fuse or the R1 fuse Fuse that connects again.
The also available another kind of input rectifying filter circuit as shown in Figure 2 of input rectifying filter circuit among Fig. 1 replaces, in Fig. 2, the input rectifying filter circuit comprises thermistor R1, fuse Fuse, filter capacitor C1, common-mode inductor L1, diode rectifier bridge and filter capacitor C2, the input of common-mode inductor L1 also meets filter capacitor C1, and the output of common-mode inductor L1 is after the diode rectifier bridge rectification and meet filter capacitor C2.NTC thermistor R1 and fuse Fuse can exchange, and C1 can be placed directly in input.
The present embodiment Switching Power Supply is provided with surge absorbing circuit, and purpose is the surge voltage that absorbs switching transistor, thereby reduces the noise of Switching Power Supply.This circuit can change over single formed (D5 short circuit, R3 open a way) by R4 and C3 and changes a voltage-stabiliser tube into again or with R4, R3, C3, the negative electrode of the negative electrode of voltage-stabiliser tube and diode D5 joins, the anode of voltage-stabiliser tube is connected on the positive pole of capacitor C2, and these three kinds of surge absorbing circuits also are applicable among the present invention.
The present embodiment Switching Power Supply also can be made into two or above output, as long as add one or more windings at transformer, one or more current rectifying and wave filtering circuits just can be realized the Switching Power Supply of many group outputs.
Claims (10)
1, a kind of Switching Power Supply comprises input rectifying filter circuit, transformer, secondary commutation filter circuit and self-maintained circuit;
Transformer is made up of the first elementary winding (T1A), the second elementary winding (T1B) and secondary winding (T1C);
Self-maintained circuit comprises charging circuit, voltage feedback circuit, first switching transistor (Q1), second switch transistor (Q2) and the 3rd diode (D8); Charging circuit is by first resistance (R2), first electric capacity (C4), the 3rd resistance (R7) in sequential series composition, and voltage feedback circuit is by the 4th resistance (R8), the 6th resistance (R10), in sequential series the forming of the 5th resistance (R9);
The voltage output of input rectifying filter circuit connects an end of the first elementary winding (T1A), this output also connects an end of the second elementary winding (T1B) through charging circuit, the elementary 0V end of another termination of the second elementary winding (T1B), the other end of the first elementary winding (T1A) is connected in series the drain electrode of second switch transistor (Q2) in turn, connect elementary 0V end behind source electrode and the 5th resistance (R9), the anode of the grid of second switch transistor (Q2) and the 3rd diode (D8), first electric capacity (C4) is connected with the link of first resistance (R2), the negative electrode of the 3rd diode (D8) connects the collection utmost point of first switching transistor (Q1), the emitter-base bandgap grading of first switching transistor (Q1) connects elementary 0V end, the end that the 5th resistance (R9) does not meet elementary 0V connects the base stage of first switching transistor (Q1) and an end of the 4th resistance (R8) through the 6th resistance (R10), another termination second elementary winding (T1B) of the 4th resistance (R8) and the link of charging circuit, the voltage output of secondary winding (T1C) connects the secondary commutation filter circuit;
It is characterized in that: also comprise short-circuit protection circuit; described short-circuit protection circuit comprises the 13 resistance (R19), the 6th electric capacity (C13) and first diode (D6); one termination, first electric capacity (C4) of the 13 resistance (R19) and the link of first resistance (R2); the negative electrode of another termination first diode (D6) of the 13 resistance (R19) and an end of the 6th electric capacity (C13); the anode of first diode (D6) connects elementary 0V end, another termination the 3rd resistance (R7) of the 6th electric capacity (C13) and the link of first electric capacity (C4).
2, Switching Power Supply according to claim 1 is characterized in that: at described first electric capacity (C4) two ends and be connected to discharge circuit, first electric capacity (C4) constitutes discharge loop with discharge circuit.
3, Switching Power Supply according to claim 2, it is characterized in that: described discharge circuit comprises the 3rd switching transistor (Q4) and first current-limiting resistance (R6), the collection utmost point serial connection of the emitter-base bandgap grading of the 3rd switching transistor (Q4), first electric capacity (C4), first current-limiting resistance (R6) and the 3rd switching transistor (Q4) constitutes discharge loop, and the base stage of the 3rd switching transistor (Q4) connects elementary 0V end through the 14 resistance (R20).
4, Switching Power Supply according to claim 3, it is characterized in that: described discharge loop is in series with unidirectional conducting diode (D10), and the emitter-base bandgap grading of the 3rd switching transistor (Q4) connects the 3rd switching transistor (Q4) the collection utmost point through unidirectional conducting diode (D10), first electric capacity (C4) and first current-limiting resistance (R6) and constitutes discharge loop.
5, according to any described Switching Power Supply of claim 1～4, it is characterized in that: at the two ends of the described transformer first elementary winding (T1A) and be connected to surge voltage absorbing circuit.
6, Switching Power Supply according to claim 5, it is characterized in that: the output of described secondary commutation filter circuit is provided with feedback control circuit, and feedback control circuit is made up of first photoelectrical coupler (U1A), second photoelectrical coupler (U1B), the 7th resistance (R11), secondary voltage stabilizing circuit, the 5th electric capacity (C12), second diode (D7), second resistance (R5) and second electric capacity (C5); The output of secondary commutation filter circuit connects secondary voltage stabilizing circuit through first photoelectrical coupler (U1A), the 7th resistance (R11); The anode of second diode (D7) connects the link of the second elementary winding (T1B) and charging circuit; The elementary 0V end of one termination of the 5th electric capacity (C12), the other end is connected with the negative electrode of second diode (D7), an end of second photoelectrical coupler (U1B); The other end of second photoelectrical coupler (U1B) is connected with the link of the 4th resistance (R8) with base stage, the 6th resistance (R10) of first switching transistor (Q1) through second resistance (R5); Second electric capacity (C5) is attempted by between the base stage and emitter-base bandgap grading of first switching transistor (Q1).
7, Switching Power Supply according to claim 6, it is characterized in that: described secondary voltage stabilizing circuit comprises by the 9th resistance (R14), the tenth resistance (R15), the 3rd electric capacity (C8), the 11 resistance (R16), the constant voltage circuit that the 12 resistance (R18) and voltage-stabiliser tube (U2) constitute, the output of one terminates secondary current rectifying and wave filtering circuit of the 9th resistance (R14) and the 11 resistance (R16), the negative electrode of another termination voltage-stabiliser tube (U2) of the 9th resistance (R14), the control utmost point of another termination voltage-stabiliser tube (U2) of the 11 resistance (R16) and an end of the 12 resistance (R18), the anode of another termination voltage-stabiliser tube (U2) of the 12 resistance (R18), the tenth resistance (R15) of series connection and the 3rd electric capacity (C8) are attempted by between the negative electrode and the control utmost point of voltage-stabiliser tube (U2).
8, Switching Power Supply according to claim 7, it is characterized in that: described secondary voltage stabilizing circuit also comprises by triode (Q3), the 8th resistance (R13), the current-limiting control circuit that the 4th electric capacity (C10) and second current-limiting resistance (R12) constitute, the collection utmost point of triode (Q3) connects the negative electrode of voltage-stabiliser tube (U2), base stage connects the anode of voltage-stabiliser tube (U2) and an end of second current-limiting resistance (R12) through the 8th resistance (R13), the emitter-base bandgap grading of another termination triode (Q3) of second current-limiting resistance (R12), the 4th electric capacity (C10) is connected in parallel between the emitter-base bandgap grading and base stage of triode (Q3).
9, Switching Power Supply according to claim 8, it is characterized in that: described input rectifying filter circuit comprises diode bridge rectifier circuit and LC low pass filter, the output of diode bridge rectifier circuit connects the LC low pass filter, and the output of LC low pass filter connects the first elementary winding (T1A).
10, Switching Power Supply according to claim 8, it is characterized in that: described input rectifying filter circuit comprises thermistor (R1), fuse (Fuse), first filter capacitor (C1), inductor (L1), diode rectifier bridge and second filter capacitor (C2), connect inductor (L1) after thermistor (R1) and fuse (Fuse) series connection, the input of inductor (L1) also connects first filter capacitor (C1), and the output of inductor (L1) is after the diode rectifier bridge rectification and connect second filter capacitor (C2).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03114191 CN1225832C (en) | 2003-04-08 | 2003-04-08 | Switching power supply |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03114191 CN1225832C (en) | 2003-04-08 | 2003-04-08 | Switching power supply |
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| CN1447507A CN1447507A (en) | 2003-10-08 |
| CN1225832C true CN1225832C (en) | 2005-11-02 |
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| CN 03114191 Expired - Fee Related CN1225832C (en) | 2003-04-08 | 2003-04-08 | Switching power supply |
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| JP4724229B2 (en) | 2005-10-09 | 2011-07-13 | システム ジェネラル コーポレーション | Switching control circuit for power converter with controlled primary side |
| CN101212184B (en) * | 2007-12-21 | 2010-06-09 | 康舒科技股份有限公司 | Slope compensation method and circuit for power switching circuit |
| CN102055346B (en) * | 2009-11-09 | 2013-08-21 | 群康科技(深圳)有限公司 | Switch power supply circuit |
| CN102158102B (en) * | 2010-02-11 | 2014-11-26 | 深圳长城开发科技股份有限公司 | Anti-high voltage surge switching power supply |
| CN102055344B (en) * | 2010-12-22 | 2013-03-06 | 上海明石光电科技有限公司 | Switch power supply |
| JP5796206B2 (en) * | 2011-01-28 | 2015-10-21 | パナソニックＩｐマネジメント株式会社 | Switching power supply circuit, semiconductor light emitting device lighting device and lighting apparatus using the same |
| CN103401451A (en) * | 2013-08-02 | 2013-11-20 | 金海新源电气江苏有限公司 | Switching power supply for combiner box |
| JP2015192535A (en) * | 2014-03-28 | 2015-11-02 | サンケン電気株式会社 | Switching power unit |
| CN105826899B (en) * | 2016-05-05 | 2018-09-14 | 杰华特微电子（杭州）有限公司 | Excess temperature protection method and switching circuit with overheat protector function |
-
2003
- 2003-04-08 CN CN 03114191 patent/CN1225832C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1447507A (en) | 2003-10-08 |
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