CN2760850Y - Switch power supply capable of outputting steady power - Google Patents
Switch power supply capable of outputting steady power Download PDFInfo
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- CN2760850Y CN2760850Y CN 200420105906 CN200420105906U CN2760850Y CN 2760850 Y CN2760850 Y CN 2760850Y CN 200420105906 CN200420105906 CN 200420105906 CN 200420105906 U CN200420105906 U CN 200420105906U CN 2760850 Y CN2760850 Y CN 2760850Y
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Abstract
The utility model discloses a switching power supply capable of stabilizing output power. The utility model comprises a transformer and a self-excitation oscillator, wherein the transformer is composed of a primary winding T1-A and a primary winding T1-B; the utility model also comprises a fixed power output circuit which comprises voltage division resistors R4 and R5 and a transistor Q2, wherein input voltage signals are processed in the mode of voltage division through the voltage division resistors R4 and R5 and then connected with the base of the transistor Q2; the other end of the voltage division resistor R5 is coupled with the output stage of a switching transistor Q1 and one end of a resistor R6, and the other end of the voltage division resistor R4 is connected with the same-phase end of the primary winding T1-B; the collector of the transistor Q2 is connected in parallel with the control electrode of the switching transistor Q1, the emitter of a transistor Q2 is connected in parallel with the reverse-phase end of the primary winding T1-B and the other end of the resistor R6. Due to the adoption of the fixed power output circuit, the output power of the switching power supply is kept to be stable within a wide input and output voltage range. The utility model is particularly suitable for stable illuminating power supply and charging of batteries.
Description
Technical field
The utility model relates to a kind of Switching Power Supply of stable power output.Can satisfy the demand of stablizing power output, some other need stablize situation of power output etc. as illuminalive power-supply, battery charge and.
Background technology
The Switching Power Supply of general promotion light-emitting diode all is with special-purpose pulsewidth integrated manipulator, as " 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.Its weak point 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 also exist complicated voltage feedback circuit in the above-mentioned Switching Power Supply.
Summary of the invention
The purpose of this utility model is exactly in order to overcome above-mentioned the deficiencies in the prior art, proposes a kind of Switching Power Supply of stable power output.Especially input and output voltage needs the situation of wide region, as light-emitting diode power supply or battery charge.
The utility model realizes that the above-mentioned purpose scheme is: a kind of Switching Power Supply of stable power output, comprise transformer and self-excited oscillator, transformer is made up of elementary winding T1-A and elementary winding T1-B, the in-phase end of elementary winding T1-A is used to connect the positive pole of input voltage, self-excited oscillator comprises by resistance R 2, the charging circuit that capacitor C 3 is composed in series, the current transformation voltage feedback circuit that mainly comprises resistance R 6, primary winding T1-B and switching transistor Q1, the voltage of input is via resistance R 2, the charging circuit that capacitor C 3 is composed in series connects the in-phase end of elementary winding T1-B, the input of switching transistor Q1 and resistance R 2, capacitor C 3 also connects, the output stage of the end of oppisite phase serial connection switching transistor Q1 of elementary winding T1-A, another output stage of switching transistor Q1 connects the end of oppisite phase of elementary winding T1-B and the negative pole of input voltage by resistance R 6, also comprise the constant power output circuit, described constant power output circuit comprises divider resistance R4, R5 and transistor Q2, the voltage signal of input is through divider resistance R4, connect the base stage of transistor Q2 after the R5 dividing potential drop, another output stage of the other end of divider resistance R5 and switching transistor Q1, the one end coupling of resistance R 6, the in-phase end of the elementary winding T1-B of another termination of divider resistance R4, the collector electrode of transistor Q2 also connects the control utmost point of switching transistor Q1, the emitter of transistor Q2 also connects the end of oppisite phase of elementary winding T1-B and the other end of resistance R 6, elementary winding T1-A or elementary winding T1-B two ends output voltage signal.
Also comprise the input rectifying filter circuit, the voltage output cathode of input rectifying filter circuit connects the in-phase end of elementary winding T1-A, and the voltage output negative pole of input rectifying filter circuit connects the end of oppisite phase of elementary winding T1-B.
Described transformer also comprises secondary winding T1-C, through secondary winding T1-C two ends output voltage signal.
Also comprise the output voltage protective circuit; described output voltage protective circuit comprises capacitor C 6, diode D8, voltage-stabiliser tube Z2 and transistor Q3; the in-phase end of the negative electrode of diode D8 and connecting resistance R4 and elementary winding T1-B; the anode of diode D8 also connects the emitter of transistor Q3 and an end of capacitor C 6; the other end of capacitor C 6 also connects the end of oppisite phase of elementary winding T1-B; the base stage of transistor Q3 links to each other with the positive pole of voltage-stabiliser tube Z2; the negative pole of voltage-stabiliser tube Z2 also connects the end of oppisite phase of elementary winding T1-B, the collector electrode of transistor Q3 and connecting resistance R2 and capacitor C 3.
Also comprise delay circuit, described delay circuit comprises resistance R 13, transistor Q4 and diode D10, described resistance R 13 1 ends link to each other with the end of oppisite phase of elementary winding T1-B, the base stage coupling of the other end of resistance R 13 and transistor Q4, behind the emitter serial connection diode D10 of transistor Q4, the negative electrode of diode D10 is coupled with the in-phase end of elementary winding T1-B, an end of capacitor C 3 again, the other end coupling of the collector electrode of transistor Q4 and capacitor C 3.
Also comprise temperature-compensation circuit, described temperature-compensation circuit comprises resistance R 7 and diode D7, divider resistance R5 by diode D7 forward and switching transistor Q1 output stage, resistance R 6 and connect, the in-phase end of the elementary winding T1-B of resistance R 7 one terminations or the in-phase end of elementary winding T1-A, resistance R 7 other ends also meet divider resistance R5 and the anode of diode D7.
Described switching transistor Q1 can be field effect transistor MOSFET or bipolar transistor.
End of oppisite phase at described primary winding T1-A is provided with high frequency noise minimizing circuit, described high frequency noise reduces circuit and comprises capacitor C 11, the end of oppisite phase of the elementary winding T1-A of one termination of capacitor C 11, the end of oppisite phase coupling of the other end of capacitor C 11 and elementary winding T1-B.
Described capacitor C 3 is provided with the accelerated charging circuit, described accelerated charging circuit comprises diode D11, capacitor C 9 and resistance R 14, after capacitor C 9 and resistance R 14 series connection, one end of another termination capacitor C 3 of capacitor C 9, the other end of another termination capacitor C 3 of resistance R 14, the negative electrode of diode D11 also connects capacitor C 9, resistance R 14, and the anode of diode D11 connects the end of oppisite phase of elementary winding T1-B.
Also comprise output rectifier and filter, described output voltage signal is through the output rectifier and filter external load.
Adopt the beneficial effect of above scheme: 1,, make the power output of Switching Power Supply keep stable, extremely be fit to stable illuminalive power-supply and battery charge in quite broad input and output voltage range owing to adopted the constant power output circuit; 2, surge voltage absorbing circuit is set, absorb the energy of the leakage inductance of primary winding T1-A, thereby the voltage at the two ends of assurance primary winding T1-A is unlikely too high, breakdown switch pipe Q1, improve the useful life of switching tube Q1, thereby improve the service behaviour of whole Switching Power Supply; 3, because the output voltage protective circuit is set, during overtension, keep the circulation vibration of whole Switching Power Supply, unlikely breakdown switch pipe Q1 improves the useful life of switching tube Q1 and the device of protection output, be unlikely to be punctured, thereby improve the service behaviour of whole Switching Power Supply by too high voltages; 4, the high-frequency noise that current rectifying and wave filtering circuit can the elimination Switching Power Supply makes it unlikely and passes back in the input circuit; Piezo-resistance VDR1 wherein is as the input voltage clamper, and the high pressure that prevents from the power supply to be responded to breaks entire circuit; 5, temperature-compensation circuit can be done temperature-compensating to the conducting voltage of transistor Q2, improves the stability of whole Switching Power Supply; 6, owing to be provided with delay circuit, when Switching Power Supply is imported very high voltage, increase the needed time cycle of whole self-oscillation, lower frequency of oscillation, thereby reduce the master switch loss, reduce the working temperature of switching tube Q1, increase the working life of switching tube Q1; 7, accelerated charging circuit and delay circuit are set and work together, thereby reach the purpose of output short circuit protection; 8, high frequency noise is set and reduces circuit, reducing to external world, electromagnetic high-frequency disturbs.
Description of drawings
Also in conjunction with the accompanying drawings the utility model is described in further detail below by specific embodiment.
Fig. 1 is the utility model embodiment one circuit diagram.
Fig. 2 is the utility model embodiment two circuit diagrams.
Fig. 3 is the utility model embodiment three-circuit figure.
Fig. 4 is the utility model embodiment four circuit diagrams.
Embodiment
Embodiment one; as shown in Figure 1; a kind of Switching Power Supply of stable power output comprises input rectifying filter circuit, transformer, output rectifier and filter, self-excited oscillator, constant power output circuit, surge voltage absorbing circuit and output voltage protective circuit.
Wherein, transformer is made up of elementary winding T1-A, elementary winding T1-B and secondary winding T1-C, when the input voltage of Switching Power Supply is lower, for example is less than 48 volts, and output does not simultaneously need again to isolate with input, and then secondary winding T1-C can.
The input rectifying filter circuit comprises fuse F1, piezo-resistance VDR1, resistance R 1, diode D1, D2, D3, D4, capacitor C 1, C2 and inductance L 1.Diode D1, D2, D3, D4 constitute bridge rectifier, and capacitor C 1, C2 and inductance L 1 are formed pi type filter, with the high-frequency noise elimination of Switching Power Supply, and the unlikely input circuit of passing back.The output of input rectifying filter circuit meets elementary winding T1-A.Piezo-resistance VDR1 is as the input voltage clamper, and the high pressure that prevents from the power supply to be responded to breaks entire circuit.Direct current when input, diode D1, D2, D3, D4 can, just can as long as D1 and D4 replace with wiring.Resistance R 1 can, promptly resistance equals 0.Piezo-resistance VDR1 can.When the direct input DC power of Switching Power Supply, as when being used on the automobile, can not need the input rectifying filter circuit.
Self-excited oscillator comprises resistance R 2, capacitor C 3, resistance R 3, R6, primary winding T1-A, T1-B and switching transistor Q1.The charging circuit that the voltage output of input rectifying filter circuit is composed in series via resistance R 2, capacitor C 3, resistance R 3 connects the end of elementary winding T1-B, the input of switching transistor Q1 and resistance R 2, capacitor C 3 also connect, elementary winding T1-A links to each other with the collector electrode of switching transistor Q1, the emitter of switching transistor Q1 and the other end that meets elementary winding T1-B after resistance R 6 is connected in series.The series position of resistance R 3 and capacitor C 3 can exchange.Resistance R 3 can not exist, and promptly resistance equals 0.Switching tube Q1 can be bipolar transistor or MOS transistor.
The constant power output circuit comprises resistance R 4, R5, capacitor C 8 and transistor Q2.One end of resistance R 4 and connecting resistance R3 and elementary winding T1-B, the other end of resistance R 4 also connects an end of base stage and the resistance R 5 of transistor Q2, the other end of resistance R 5 also connects the emitter of switching transistor Q1 and an end of resistance R 6, the collector electrode of transistor Q2 and connecting resistance R2 and capacitor C 3, the emitter of transistor Q2 also connects elementary winding T1-B and resistance R 6, one end of capacitor C 8 also connects an end of base stage and the resistance R 5 of transistor Q2, the other end of capacitor C 8 and connecting resistance R6 and elementary winding T1-B.Capacitor C 8 can not exist, and promptly capacitance equals 0.
The output voltage protective circuit comprises resistance R 9, R10, R11, capacitor C 6, diode D8, voltage-stabiliser tube Z2 and transistor Q3.The negative electrode of diode D8 is by resistance R 9 and connecting resistance R4 and elementary winding T1-B, the anode of diode D8 also connects emitter and the capacitor C 6 of transistor Q3, the other end of capacitor C 6 also connects elementary winding T1-B and resistance R 6, the base stage of transistor Q3 links to each other with the positive pole of voltage-stabiliser tube Z2, the negative pole of voltage-stabiliser tube Z2 is by resistance R 11 and connect elementary winding T1-B and resistance R 6, one end of resistance R 10 also connects emitter and the capacitor C 6 of transistor Q3, the other end of resistance R 10 also connects the base stage of transistor Q3 and the positive pole of voltage-stabiliser tube Z2, the collector electrode of transistor Q3 and connecting resistance R2 and capacitor C 3.Resistance R 9, R11 can, promptly resistance equals 0.Resistance R 10 can, promptly resistance equals ∞.
Output rectifier and filter comprises rectifier diode D6, capacitor C 4, C5.The positive pole of rectifier diode D6 connects the end of oppisite phase of secondary winding T1-C, and the negative pole of rectifier diode D6 links to each other with the in-phase end of secondary winding T1-C by capacitor C 5.Load can be several light-emitting diodes of series connection or rechargeable battery, and the positive pole of load connects the positive pole of rectifier diode D6, and the negative pole of load connects the in-phase end of secondary winding T1-C.Filter capacitor C7 one end links to each other with the in-phase end of secondary winding T1-C, and the end of filter capacitor C7 also connects elementary winding T1-B and resistance R 6.Capacitor C 4, C5 can, promptly capacitance equals 0.When input voltage is lower, for example be less than 20 volts, filter capacitor C7 also can.
Surge voltage absorbing circuit comprises diode D5 and voltage-stabiliser tube Z1.The negative electrode of diode D5 links to each other with the negative pole of voltage-stabiliser tube Z1, and the anode of diode D5 links to each other with the end of oppisite phase of elementary winding T1-A, and the positive pole of voltage-stabiliser tube Z1 links to each other with the in-phase end of elementary winding T1-A.Surge voltage absorbing circuit will be by the energy absorption of the leakage inductance of transformer T1-A, and is unlikely too high with the voltage at the two ends that guarantee T1-A, breakdown switch pipe Q1.When input voltage is lower, for example be less than 20 volts, surge voltage absorbing circuit can.
The course of work is as follows:
The load of Switching Power Supply can be that light-emitting diode, storage battery or other need be stablized the load of power output.Switching transistor Q1 contains a connection stage and an off-phases during operation, this Switching Power Supply is powered by elementary winding T1-B, and elementary winding T1-B, self-excited oscillator, constant power output circuit are realized jointly to the power supply of light-emitting diode or the charging of storage battery.
Self-oscillation: switching transistor Q1 connects via a high resistant resistance R 2, an elementary winding T1-B, capacitor C 3,3 continuous steps of low-resistance resistance R during connecting.At first, the DC power supply of capacitor C 2 outputs is charged to capacitor C 3 through resistance R 2, voltage on capacitor C 3 rises to switching transistor Q1 conducting voltage, switching transistor Q1 enters the deep layer conducting, the electric current of primary winding T1-A begins to rise, this electric current flow through simultaneously switching transistor Q1 and resistance R 6.Voltage rising when resistance R 6, and the resistance R 5 in the constant power output circuit is added to the voltage on the resistance R 6 on the base stage of transistor Q2, voltage on transistor Q2 base stage rises to and makes transistor Q2 conducting, voltage on the switching transistor Q1 base stage reduces and makes switching transistor Q1 end, and elementary winding T1-B produces a negative voltage makes switching transistor Q1 quicken to end.Simultaneously, the energy that is stored among the transformer T also begins to see through secondary winding T1-C, diode D6, capacitor C4 to capacitor C 5 and load discharge, finish until all energy releases of Switching Power Supply, switching transistor Q1 is conducting again more again, so just finishes a cycle of oscillation.
In the constant power output circuit, the base voltage of transistor Q2 is made of two voltage additions, and one is the voltage on the resistance R 6, receives the base stage of transistor Q2 through resistance R 5.Another is the voltage on the elementary winding T1-B, receives through resistance R 4 on the base stage of transistor Q2.By being directly proportional with voltage on being added to elementary winding T1-A through the forward voltage on the elementary winding T1-B, ratio is exactly the number of turns ratio of elementary winding T1-B and elementary winding T1-A.So as resistance R 4 is received on the contact of resistance R 2 and capacitor C 2, its effect is the same.When just input voltage was very high, the power consumption of resistance R 4 was bigger, so when low-voltage is imported, for example 48 volts below the DC, generally all can directly receive on the capacitor C 2 of direct current output point.Resistance R 4 is added to a voltage that is proportional to input on the base stage of transistor Q2, when input voltage big more, resistance R 4 is also big more at the bias voltage of transistor Q2 base stage, because the conducting voltage of transistor Q2 is constant under certain environment, so it is big more to work as input voltage, electric current required on the resistance R 6 is also more little, makes transistor Q2 conducting with regard to being enough to produce enough big voltage, and switching transistor Q1 ends.So it is high more to work as input voltage, the electric current of the primary of flowing through winding T1-A, switching transistor Q1, resistance R 6 is then few more.When load current is excessive, the corresponding increase of the electric current of the resistance R of flowing through 6, the voltage negative feedback effect of resistance R 6 make the base voltage of switching transistor Q1 reduce, thereby the conducting state of control switch transistor Q1 reduces electric current in the further conducting of transistor Q2.Just can make power output in quite broad input voltage range as long as suitably choose the numerical value of resistance R 4, R5, R6, keep stable, reach firm power control.
When input voltage is lower, for example be less than 20 volts, output does not simultaneously need again to isolate with input that then secondary winding T1-C can.Surge absorbing circuit diode D5, voltage-stabiliser tube Z1 also can, filter capacitor C7 also can.
The output voltage protective circuit: when transformer T1 flyback, elementary winding T1-B sees through resistance R 9, and diode D8 is to capacitor C 6 chargings, and the charging voltage on the capacitor C 6 is determined by the ratio of power output secondary winding T1-C and elementary winding T1-B.If this ratio is N, and output voltage is V
0, then the voltage on the capacitor C 6 is=V
0/ N, and V
0Determined by load light-emitting diode or storage battery.Resistance R 10, R11, voltage-stabiliser tube Z2 and transistor Q3 form a voltage detecting circuit.Resistance R 10, R11 and transistor Q3 constitute the Vbe amplifier, so the trigger voltage of whole group circuit is the conducting voltage of Vbe (R10+R11)/R10+Z2.
When output voltage is too high, make the voltage on the capacitor C 6 be raised to the whole trigger voltage of organizing circuit, transistor Q3 conducting descends the voltage of transistor Q1, and Q1 is ended.Because of capacitor C 6 much larger than capacitor C 3, end so transistor Q1 keeps, reduce to the trigger voltage that is less than whole group circuit until the voltage of capacitor C 6, the voltage on the capacitor C 3 just can rise to the conducting voltage of transistor Q1, whole recirculation cycle of oscillation.
Embodiment two, as shown in Figure 2, be, when the time directly by the two ends output voltage of elementary winding T1-A with the difference of embodiment one, the anode of rectifier diode D6 connects the end of oppisite phase of elementary winding T1-A, and the negative electrode of rectifier diode D6 links to each other with the in-phase end of elementary winding T1-A by capacitor C 5.Load can be several light-emitting diodes of series connection or rechargeable battery, and the positive pole of load connects the negative electrode of rectifier diode D6, and the negative pole of load connects the end in the same way of elementary winding T1-A.Capacitor C 4, C5 can, promptly capacitance equals 0.
Embodiment three, as shown in Figure 3, be, when the time directly by the two ends output voltage of elementary winding T1-B with the difference of embodiment one, the anode of rectifier diode D6 connects the end of oppisite phase of elementary winding T1-B, and the negative electrode of rectifier diode D6 links to each other with the in-phase end of elementary winding T1-B by capacitor C 5.Load can be several light-emitting diodes of series connection or rechargeable battery, and the positive pole of load connects the negative electrode of rectifier diode D6, and the negative pole of load connects the end in the same way of elementary winding T1-B.Capacitor C 4, C5 can, promptly capacitance equals 0.
Embodiment four, as shown in Figure 4, are that with first difference of embodiment one be provided with delay circuit at the two ends of capacitor C 3, delay circuit comprises resistance R 13, transistor Q4, diode D10, resistance R 12.Described resistance R 13 1 ends link to each other with the end of oppisite phase of elementary winding T1-B, the other end of resistance R 13 links to each other with the base stage of transistor Q4, the emitter of transistor Q4 links to each other with the anode of diode D10, the negative electrode of diode D10 is linked resistance R 3 and is linked on the contact of elementary winding T1-B again, and the collector electrode of transistor Q4 is linked on the contact of capacitor C 3 and switching tube Q1 base stage by resistance R 12.
When transistor Q2 conducting, switching tube Q1 closes, and becomes negative voltage with the tie point of resistance R 3, electric current flow through resistance R 13, transistor Q4, diode D10, resistance R 3, elementary winding T1-B.This electric current makes transistor Q4 conducting, and capacitor C 3 is through resistance R 12, transistor Q4, diode D10 discharge.After the magnetic energy that is stored in transformer T1 discharges fully, the vanishing of elementary winding T1-B both end voltage, capacitor C 3 is through resistance R 2 chargings, voltage on capacitor C 3 is charged to the conducting voltage of switching tube Q1, switching tube Q1 conducting, electric current flow through primary winding T1-A, switching tube Q1, resistance R 6 flow back to power cathode again, at this moment produce a forward voltage and make switching tube Q1 enter the deep layer conducting on elementary winding T1-B.The electric current of primary winding T1-A rises, and the voltage of resistance R 6 rises until transistor Q2 conducting, and repeat whole cycle of oscillation once more.
In the above-mentioned delay circuit, the series position of diode D10 and transistor Q4 can exchange, and promptly receives the base stage of transistor Q4 after diode D10 and resistance R 13 series connection again, and the emitter-base bandgap grading of transistor Q4 is received on the contact of resistance R 3 and capacitor C 3.In addition because the value of general resistance R 3 is not very big, so the negative electrode of diode D10 can be received on the contact of resistance R 3 and elementary winding T1-B.The value of resistance R 12 can be zero, and promptly the collector electrode of transistor Q4 is directly received on the contact of capacitor C 3 and switching tube Q1 base stage.The serial connection position of resistance R 3 and capacitor C 3 can exchange.
Embodiment four is with second difference of embodiment one, has increased temperature-compensation circuit, accelerated charging circuit and high frequency noise and has reduced circuit.Temperature-compensation circuit comprises resistance R 7 and diode D7, and divider resistance R5 links to each other with the emitter of switching transistor Q1 by diode D7, the in-phase end of the elementary winding T1-B of resistance R 7 one terminations, and resistance R 7 other ends also meet divider resistance R5 and the anode of diode D7.The negative electrode of diode D7 connects the contact of switching tube Q1 and resistance R 6.
When the switching transistor conducting, the electric current resistance R 6 of flowing through, on resistance R 6, produce a voltage, meanwhile, the tie point of primary winding T1-B and diode D7 also produces a positive voltage, this voltage makes the electric current resistance R 7 of flowing through, diode D7, resistance R 6 flows back to power supply negative terminal again, because the resistance value of resistance R 7 is quite big, and the resistance value of resistance R 6 is very little, so the voltage that the electric current of the diode D7 that flows through is produced on resistance R 6 is very little, this electric current is the bias current of diode, makes diode produce a forward conduction voltage V
F, the voltage addition on this voltage and the resistance R 6 is added the voltage that resistance R 4 and resistance R 5 produced and is added on the base stage of transistor Q2, when the base voltage Vbe of transistor Q2 arrives the conducting voltage of transistor Q2, and transistor Q2 conducting, switching tube Q1 closes.
In addition, the end that resistance R 7 links to each other with the in-phase end of elementary winding T1-B also can be received the positive pole of power supply, promptly receives the in-phase end of elementary winding T1-A, so that the bias current of diode D7 to be provided.
When ambient temperature changes, the forward conduction voltage V of diode
FCan present negative temperature coefficientization, and the required conducting voltage of transistor Q2 also is the negative temperature coefficient variation, the chances are-2mv/ ℃, as long as suitably choose diode and its operating current, the conducting voltage of transistor Q2 can be done good temperature-compensating, makes variations in temperature very little with the variations in temperature of the conducting that makes transistor Q2 to the electric current of the required resistance R 6 of flowing through.
Accelerated charging circuit:, be provided with accelerated charging circuit and delay circuit and work together in order to reach the purpose of output short circuit protection.The accelerated charging circuit comprises diode D11, capacitor C 9 and resistance R 14, after capacitor C 9 and resistance R 14 series connection, one end of another termination capacitor C 3 of capacitor C 9, the other end of another termination capacitor C 3 of resistance R 14, the negative electrode of diode D11 also connects capacitor C 9, resistance R 14, and the anode of diode D11 connects the end of oppisite phase of elementary winding T1-B.
In normal operating conditions, when switching transistor Q1 closed, the in-phase end of elementary winding T1-B was a negative voltage, and electric current flows through the in-phase end that diode D11, capacitor C 9 and resistance R 3 flow to elementary winding T1-B by power supply negative terminal.Capacitor C 9 is by this current charges.Finish when transformer energy discharges, elementary winding T1-B two ends are no-voltages, and transistor Q4 is no longer with capacitor C 3 discharges, and capacitor C 3 begins to see through resistance R 2 and resistance R 14 chargings.When output short-circuit, the voltage at elementary winding T1-B two ends seldom can not be to capacitor C 9 chargings, and therefore, capacitor C 9 can not see through resistance R 14 to capacitor C 3 accelerated chargings.Charging current is only by resistance R 2 chargings.
During design, resistance R 14 is provided than resistance R 2 big a lot of charging currents, make entire circuit very fast in the charging of capacitor C 3 just often, operating frequency is normal; When short circuit, 3 of capacitor C are by resistance R 2 chargings, and charging is slow a lot, and operating frequency is much lower, thereby the power during short-circuit condition is also very little, and the circuit of whole Switching Power Supply is protected.
High frequency noise reduces circuit: comprise capacitor C 11 and resistance R 15, and after capacitor C 11 and resistance R 15 series connection, the end of oppisite phase of the elementary winding T1-A of another termination of capacitor C 11, the end of oppisite phase of the elementary winding T1-B of another termination of resistance R 15.When switching transistor Q1 closes, the inductance of elementary winding T1-B or leakage inductance and capacitor C 11 resonance, much lower when this frequency ratio does not have capacitor C 11, so high frequency noise is also few a lot.When switching transistor Q1 conducting, capacitor C 11 is through switching transistor Q1, resistance R 6, resistance R 15 discharges, makes capacitor C 11 at another cycle resonance once more.
Wherein the value of resistance R 15 can be zero, promptly is equivalent to resistance R 15 short circuits.
In embodiment one to four, the serial connection position of resistance R 3 and capacitor C 3 all can exchange.
If in transformer T, increase winding and output rectification circuit, just can make the multi-output switching power supply, the gross power of its output is by fixedly output power circuit restriction.
Claims (10)
1, a kind of Switching Power Supply of stable power output, comprise transformer and self-excited oscillator, transformer is made up of elementary winding T1-A and elementary winding T1-B, the in-phase end of elementary winding T1-A is used to connect the positive pole of input voltage, self-excited oscillator comprises by resistance R 2, the charging circuit that capacitor C 3 is composed in series, the current transformation voltage feedback circuit that mainly comprises resistance R 6, primary winding T1-B and switching transistor Q1, the voltage of input is via resistance R 2, the charging circuit that capacitor C 3 is composed in series connects the in-phase end of elementary winding T1-B, the input of switching transistor Q1 and resistance R 2, capacitor C 3 also connects, the output stage of the end of oppisite phase serial connection switching transistor Q1 of elementary winding T1-A, another output stage of switching transistor Q1 connects the end of oppisite phase of elementary winding T1-B and the negative pole of input voltage by resistance R 6, it is characterized in that: also comprise the constant power output circuit, described constant power output circuit comprises divider resistance R4, R5 and transistor Q2, the voltage signal of input is through divider resistance R4, connect the base stage of transistor Q2 after the R5 dividing potential drop, another output stage of the other end of divider resistance R5 and switching transistor Q1, the one end coupling of resistance R 6, the in-phase end of the elementary winding T1-B of another termination of divider resistance R4, the collector electrode of transistor Q2 also connects the control utmost point of switching transistor Q1, the emitter of transistor Q2 also connects the end of oppisite phase of elementary winding T1-B and the other end of resistance R 6, elementary winding T1-A or elementary winding T1-B two ends output voltage signal.
2, the Switching Power Supply of a kind of stable power output according to claim 1, it is characterized in that: also comprise the input rectifying filter circuit, the voltage output cathode of input rectifying filter circuit connects the in-phase end of elementary winding T1-A, and the voltage output negative pole of input rectifying filter circuit connects the end of oppisite phase of elementary winding T1-B.
3, the Switching Power Supply of a kind of stable power output according to claim 1 is characterized in that: described transformer also comprises secondary winding T1-C, through secondary winding T1-C two ends output voltage signal.
4; the Switching Power Supply of a kind of stable power output according to claim 1; it is characterized in that: also comprise the output voltage protective circuit; described output voltage protective circuit comprises capacitor C 6; diode D8; voltage-stabiliser tube Z2 and transistor Q3; the in-phase end of the negative electrode of diode D8 and connecting resistance R4 and elementary winding T1-B; the anode of diode D8 also connects the emitter of transistor Q3 and an end of capacitor C 6; the other end of capacitor C 6 also connects the end of oppisite phase of elementary winding T1-B; the base stage of transistor Q3 links to each other with the positive pole of voltage-stabiliser tube Z2; the negative pole of voltage-stabiliser tube Z2 also connects the end of oppisite phase of elementary winding T1-B, the collector electrode of transistor Q3 and connecting resistance R2 and capacitor C 3.
5, the Switching Power Supply of a kind of stable power output according to claim 1, it is characterized in that: also comprise delay circuit, described delay circuit comprises resistance R 13, transistor Q4 and diode D10, described resistance R 13 1 ends link to each other with the end of oppisite phase of elementary winding T1-B, the base stage coupling of the other end of resistance R 13 and transistor Q4, behind the emitter serial connection diode D10 of transistor Q4, the negative electrode of diode D10 is coupled with the in-phase end of elementary winding T1-B, an end of capacitor C 3 again, the other end coupling of the collector electrode of transistor Q4 and capacitor C 3.
6, the Switching Power Supply of a kind of stable power output according to claim 1, it is characterized in that: also comprise temperature-compensation circuit, described temperature-compensation circuit comprises resistance R 7 and diode D7, divider resistance R5 by diode D7 forward and switching transistor Q1 output stage, resistance R 6 and connect, the in-phase end of the elementary winding T1-B of resistance R 7 one terminations or the in-phase end of elementary winding T1-A, resistance R 7 other ends also meet divider resistance R5 and the anode of diode D7.
7, the Switching Power Supply of a kind of stable power output according to claim 1 is characterized in that: described switching transistor Q1 can be field effect transistor MOSFET or bipolar transistor.
8, the Switching Power Supply of a kind of stable power output according to claim 1, it is characterized in that: the end of oppisite phase at described primary winding T1-A is provided with high frequency noise minimizing circuit, described high frequency noise reduces circuit and comprises capacitor C 11, the end of oppisite phase of the elementary winding T1-A of one termination of capacitor C 11, the end of oppisite phase coupling of the other end of capacitor C 11 and elementary winding T1-B.
9, the Switching Power Supply of a kind of stable power output according to claim 5, it is characterized in that: described capacitor C 3 is provided with the accelerated charging circuit, described accelerated charging circuit comprises diode D11, capacitor C 9 and resistance R 14, after capacitor C 9 and resistance R 14 series connection, one end of another termination capacitor C 3 of capacitor C 9, the other end of another termination capacitor C 3 of resistance R 14, the negative electrode of diode D11 also connects capacitor C 9, resistance R 14, and the anode of diode D11 connects the end of oppisite phase of elementary winding T1-B.
10, according to the Switching Power Supply of one of them described a kind of stable power output of claim 1-9, it is characterized in that: also comprise output rectifier and filter, described output voltage signal is through the output rectifier and filter external load.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420105906 CN2760850Y (en) | 2004-12-29 | 2004-12-29 | Switch power supply capable of outputting steady power |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200420105906 CN2760850Y (en) | 2004-12-29 | 2004-12-29 | Switch power supply capable of outputting steady power |
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| Publication Number | Publication Date |
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| CN2760850Y true CN2760850Y (en) | 2006-02-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 200420105906 Expired - Fee Related CN2760850Y (en) | 2004-12-29 | 2004-12-29 | Switch power supply capable of outputting steady power |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8031490B2 (en) | 2006-08-25 | 2011-10-04 | Panasonic Electric Works Co., Ltd. | Power supply circuit and power supply system |
| CN101277065B (en) * | 2008-01-18 | 2013-07-24 | 天宝电子（惠州）有限公司 | Switch power supply of inverse-excitation type self-excitation converting circuit RCC |
| CN104883043A (en) * | 2014-02-28 | 2015-09-02 | 深圳市海洋王照明工程有限公司 | Switching mode power supply |
| CN107646165A (en) * | 2015-05-22 | 2018-01-30 | 飞利浦照明控股有限公司 | LED driver and LED driving methods |
-
2004
- 2004-12-29 CN CN 200420105906 patent/CN2760850Y/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8031490B2 (en) | 2006-08-25 | 2011-10-04 | Panasonic Electric Works Co., Ltd. | Power supply circuit and power supply system |
| CN101507091B (en) * | 2006-08-25 | 2012-03-07 | 松下电工株式会社 | Power supply circuit and power supply system |
| CN101277065B (en) * | 2008-01-18 | 2013-07-24 | 天宝电子（惠州）有限公司 | Switch power supply of inverse-excitation type self-excitation converting circuit RCC |
| CN104883043A (en) * | 2014-02-28 | 2015-09-02 | 深圳市海洋王照明工程有限公司 | Switching mode power supply |
| CN107646165A (en) * | 2015-05-22 | 2018-01-30 | 飞利浦照明控股有限公司 | LED driver and LED driving methods |
| CN107646165B (en) * | 2015-05-22 | 2020-01-17 | 飞利浦照明控股有限公司 | LED driver and LED driving method |
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