CN210405090U - BUCK converter circuit and direct current voltage reduction device using same - Google Patents
BUCK converter circuit and direct current voltage reduction device using same Download PDFInfo
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- CN210405090U CN210405090U CN201921818338.2U CN201921818338U CN210405090U CN 210405090 U CN210405090 U CN 210405090U CN 201921818338 U CN201921818338 U CN 201921818338U CN 210405090 U CN210405090 U CN 210405090U
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Abstract
The utility model relates to a BUCK converter circuit and applied this circuit's direct current step-down device mainly includes: the device comprises a switching tube, an energy storage inductor, a freewheeling diode, a filter capacitor, a control circuit, an overvoltage protector, a starting circuit and an oscillation feedback circuit; the control circuit comprises a driving circuit and an accelerating circuit, and further, a voltage sampling circuit, a current sampling circuit and a comparison circuit are added into an output circuit, so that the BUCK converter with ultra-wide voltage input, ultra-low power consumption, high efficiency, simple circuit topology and easy realization and the direct-current voltage reduction device with overcurrent and short-circuit protection and stable output voltage are realized.
Description
Technical Field
The utility model belongs to the technical field of electronic product, a DC step-down device of BUCK converter and applied this circuit with super wide voltage input and low-power consumption high efficiency characteristic is related to.
Background
In various switching power supplies, a BUCK circuit is generally adopted for a non-isolated step-down power supply, and in the existing DC-DC circuit on the market, the following are mainly adopted:
1. the special power supply chip is simple in circuit application, but high in cost, the voltage range of an input power supply is limited, the special power supply chip cannot normally work within the voltage range of the input power supply from several volts to hundreds of volts, the standby power consumption is high, generally, the standby power consumption is dozens or even hundreds of milliwatts, the low power consumption requirement of a product cannot be met, the power supply conversion efficiency is very low under the light load (such as 1mA output) working condition, generally, the power supply conversion efficiency is only 15% -30%, and the application requirement of high efficiency under the low power consumption condition cannot be met.
2. Discrete components, such as RCC circuits, etc., have the advantages of: the circuit structure is simple, and the voltage output performance which can be realized only by a special chip can be obtained only by a few discrete components; the RCC has the following defects: the efficiency is low, the transformer requires highly (the parameter is difficult to guarantee) and leads to producing the finished product defective rate high.
3. In other BUCK circuits, the power-on starting circuit and the normal working bias circuit are shared and are directly connected with the input power supply end, so that even after the power-on starting is finished, the front-stage input power supply end supplies power to provide bias for the control circuit, the input voltage range cannot be wide enough, and the efficiency improvement space is limited due to large loss.
Disclosure of Invention
The to-be-solved technical problem of the utility model lies in, to the above-mentioned defect of prior art, provide a DC step-down device of super wide voltage input, ultra-low power consumption, more efficient BUCK converter circuit and applied this circuit.
The utility model provides a technical scheme that its technical problem adopted is:
a BUCK converter circuit is constructed, mainly comprising: the circuit comprises a switching tube 2, an energy storage inductor 3, a freewheeling diode 4, a filter capacitor 5, an overvoltage protector 9, a control circuit 6, a starting circuit 7 and an oscillation feedback circuit 8, wherein the control circuit comprises a driving circuit 61 and an accelerating circuit 62; a source electrode S of the switch tube 2 is connected with an input power supply end VIN, a drain electrode D of the switch tube 2 is connected with one end of an energy storage inductor 3 and a cathode K of a fly-wheel diode 4, the other end of the energy storage inductor 3 is connected with a positive electrode end of a filter capacitor 5 and a low-voltage direct current power supply end VCC, an anode A of the fly-wheel diode 4, a cathode of the filter capacitor 5 and a grounding end of a control circuit 6 are connected with a power supply common ground GND, an input end NET2 of the control circuit 6 is connected with one end of a starting circuit 7 and one end of an oscillation feedback circuit 8, an output end of the control circuit 6 is respectively connected with the source electrode S and a grid electrode G of the switch tube 2, the other end of the starting circuit 7 is connected with the input power supply end VIN, the other end of the oscillation feedback circuit 8 is connected with a connection point NET1 of the switch tube 2 and the energy storage inductor 3, two ends of, and the third end of the starting circuit 7 is connected with the rear-stage low-voltage direct-current output end.
Furthermore, a voltage sampling circuit or a current sampling circuit and a comparison circuit are added in the output circuit, so that the BUCK converter with ultra-wide voltage input, ultra-low power consumption, higher efficiency and simple circuit topology and easy realization and the direct-current voltage reduction device with overcurrent and short-circuit protection and stable output voltage are realized.
Compared with the prior art, the beneficial effects of the utility model are that:
1. ultra-wide input voltage range: the input working voltage range is 5V to 600V, and the application requirements of various wide-range power supply voltages are met.
2. Ultra-low power consumption: the input power is less than 5 milliwatts under typical light load (outputting 1 mA), and the input power is less than 1 milliwatt under micro load (outputting 100 uA), so that the requirement of products with extremely strict power consumption is met, and a zero-power-consumption standby power supply can be realized.
3. The full-load maximum efficiency reaches more than 90%, the conversion efficiency is high when the light-load application is carried out, the conversion efficiency is up to more than 65%, and the application requirements of low power consumption and high efficiency are met.
4. And a special power supply chip and a transformer are not needed, so that the production cost is reduced to a certain extent.
5. The power-on starting circuit is automatically disconnected after power-on starting is finished, and the feedback bias circuit structure is connected to the rear-stage low-voltage direct-current output end, so that the input voltage range is further widened, the loss is effectively reduced, and the conversion efficiency is improved.
Drawings
Fig. 1 is a schematic block diagram of an embodiment of a BUCK converter circuit and a dc voltage reduction device using the same.
Fig. 2 is a circuit diagram of an embodiment of a BUCK converter circuit and a dc voltage reduction device using the same.
Detailed Description
In order to facilitate the technical solutions of the present invention for those skilled in the art to understand, the present invention is further described in detail below with reference to the accompanying drawings, and the contents mentioned in the embodiments are not intended to limit the present invention.
As shown in fig. 1, the BUCK converter circuit 1 of the present invention includes: the device comprises a switching tube 2, an energy storage inductor 3, a freewheeling diode 4, a filter capacitor 5 and a control circuit 6;
a source S of the switch tube 2 is connected with an input power supply end VIN, a drain D of the switch tube 2 is connected with one end of an energy storage inductor 3 and a cathode K of a fly-wheel diode 4, the other end of the energy storage inductor 3 is connected with a positive end of a filter capacitor 5, an anode A of the fly-wheel diode 4 and a negative electrode of the filter capacitor 5 are connected with a power supply common ground GND, and an output end of the control circuit 6 is connected with a grid G of the switch tube 2;
the BUCK converter circuit 1 further includes: an overvoltage protector 9, a starting circuit 7 and an oscillation feedback circuit 8;
the control circuit 6 comprises a driving circuit 61 and an accelerating circuit 62;
the grounding end of the control circuit 6 is connected with a power supply common ground GND;
an input end NET2 of the control circuit 6 is connected with one end of the starting circuit 7 and one end of the oscillation feedback circuit 8, a power supply end of the control circuit 6 is connected with a source electrode S of the switching tube 2, the other end of the starting circuit 7 is connected with an input power supply end VIN, the other end of the oscillation feedback circuit 8 is connected with a connection point NET1 of the switching tube 2 and the energy storage inductor 3, and two ends of the overvoltage protector 9 are connected in parallel between a grid G and the source electrode S of the switching tube 2;
the switch tube 2 comprises a P-channel field effect tube or a PNP triode;
the freewheel diode 4 comprises a fast recovery diode or a schottky diode;
the third end of the starting circuit 7 is connected with the rear-stage low-voltage direct-current output end;
the low-voltage direct current power supply end VCC is connected with a rear-stage load;
the starting circuit 7 comprises a power-on starting circuit 71 and a low-voltage bias circuit 72;
the power-on starting circuit 71 is composed of a resistor and a capacitor which are connected in series or only composed of a resistor, one end of the power-on starting circuit is connected with the input end of the control circuit, and the other end of the power-on starting circuit is connected with the input power end;
the low-voltage bias circuit 72 is formed by connecting a resistor and a diode in series or only by a resistor, one end of the low-voltage bias circuit 72 is connected with an input end NET2 of the control circuit 6, and the other end of the low-voltage bias circuit 72 is connected with a rear-stage low-voltage direct-current output end;
the low-voltage dc output of the post-stage includes a dc output voltage directly or indirectly applied to the filter capacitor 5, including but not limited to: a low-voltage direct current power supply terminal VCC and an output voltage terminal VOUT.
The overvoltage protector 9 comprises a transient voltage suppressor TVS, or a voltage stabilizing diode, or a voltage dependent resistor, or an ESD suppressor, or a ceramic gas discharge tube;
the driving circuit 61 comprises a constant current circuit formed by triodes, or a switching circuit formed by field effect transistors;
the accelerating circuit 62 is composed of a triode, a resistor and a diode, or only a resistor;
the oscillation feedback circuit 8 is formed by connecting a resistor and a capacitor in series;
furthermore, on the basis of the BUCK converter circuit, a voltage sampling circuit, a current sampling circuit and a comparison circuit are added into an output circuit, so that the BUCK converter with ultra-wide voltage input, ultra-low power consumption, high efficiency, simple circuit topology and easy realization and a direct-current voltage reduction device with overcurrent and short-circuit protection and stable output voltage are realized.
The following describes the implementation manner of each part of the circuit in detail with reference to the circuit structure diagram of the embodiment:
as shown in figure 2 of the drawings, in which,
the switching tube 2 includes a switching tube Q1, including but not limited to: a P-channel fet, or a PNP triode.
The energy storage inductance 3 includes an inductor L1, including but not limited to: a chip power inductor, or a magnetic glue inductor, or an integrally formed inductor, or an I-shaped inductor, or a transformer inductor.
The freewheeling diode 4 includes a freewheeling diode D2 including, but not limited to: fast recovery diodes, or schottky diodes;
the filter capacitance 5 includes a capacitor C3, including but not limited to: electrolytic capacitors, or tantalum capacitors;
the overvoltage protector 9 includes a transient voltage suppressor TVS Z1, or is replaced with other similar functional devices, including but not limited to: the device comprises a transient voltage suppressor TVS, or a voltage stabilizing diode, or a piezoresistor, or an ESD suppressor, or a transient voltage suppressor TVS, or a ceramic gas discharge tube;
the driving circuit 61 comprises a constant current circuit consisting of a triode Q3, a triode Q5 and a resistor R2, or only a resistor R2 and a triode Q3 (the triode Q5 is not used), or only a resistor R2 and a triode Q3 and a field effect tube are used for replacing the triode;
the speed-up circuit 62 comprises a transistor Q2, a resistor R1, a diode D1 or only comprises a resistor R1;
the starting circuit 7 comprises a power-on starting circuit 71 and a low-voltage bias circuit 72;
the power-on starting circuit 71 is formed by connecting a resistor R3 and a capacitor C5 in series, one end of a resistor R3 is connected with an input end NET2 of the control circuit 6, the other end of the resistor R3 is connected with one end of a capacitor C5, and the other end of a capacitor C5 is connected with an input power supply end VIN;
the low-voltage bias circuit 72 is formed by connecting a resistor R9 and a diode D3 in series, one end of a resistor R9 is connected with an input end NET2 of the control circuit 6, the other end of the resistor R9 is connected with the cathode of a diode D3, and the anode of a diode D3 is connected with a low-voltage direct-current power supply end VCC;
the oscillation feedback circuit 8 comprises a resistor R5 and a capacitor C2 which are connected in series and connected between an input end NET2 of the control circuit 6 and a connection point NET1 of the switch tube and the energy storage inductor.
The overvoltage protector 9:
the overvoltage protector 9 includes a transient voltage suppressor TVS, or is replaced with other similar functional devices, including but not limited to: a transient voltage suppressor TVS, or a zener diode, or a varistor, or an ESD suppressor, or a ceramic gas discharge tube.
The specific embodiment is as follows:
the overvoltage protection device 9 includes a transient voltage suppressor TVS Z1, and two ends of an anode and a cathode of the transient voltage suppressor Z1 are respectively connected in parallel between the gate G and the source S of the switching transistor 2, for protecting the switching transistor 2 from being damaged due to the voltage of the input power source terminal VIN exceeding the VGS limit value of the switching transistor 2.
The control circuit 6:
the BUCK converter consists of a non-special power supply chip, is combined with a starting circuit 7 and an oscillation feedback circuit 8, realizes the optimized control of the BUCK converter, and has higher conversion efficiency and the like in three aspects of ultra-wide input voltage range, ultra-low power consumption, light-load application and the like, and exceeds the special power supply chip;
the control circuit 6 includes a driving circuit 61 and an accelerating circuit 62.
The drive circuit 61:
the driving circuit 61 includes a constant current circuit formed by a transistor, or a switching circuit formed by a field effect transistor.
The specific embodiment is as follows:
the driving circuit 61 is composed of transistors Q3, Q5 and a resistor R2, and the basic connection relationship is as follows: an emitter of the triode Q3 is connected with a base of the triode Q5 and one end of the resistor R2, an emitter of the triode Q5 and the other end of the resistor R2 are connected to a power common ground GND, a base of the triode Q3 is connected with a collector of the triode Q5, one end of the starting resistor R3, one end of the oscillation feedback resistor R5, an output end of the comparison circuit 10 and an input end NET2 of the control circuit 6, and a collector of the triode Q3 is connected with one end of the R1 in the acceleration circuit, the base of the Q1 in the acceleration circuit and a cathode of the D1 in the acceleration circuit. The working process is as follows: the transistor Q3 is used for pushing the switch tube Q1, and the resistor R2 and the transistor Q5 are used for limiting the maximum driving current of the switch tube Q1;
the third triode Q3 comprises a Darlington composite tube, or a composite tube formed by two triodes, or a single triode;
the fifth triode Q5 comprises an NPN triode or an N-channel field effect transistor.
The speed-up circuit 62:
the speed-up circuit 62 may comprise a transistor, a resistor, a diode, or may comprise only a resistor.
The specific embodiment is as follows:
the accelerating circuit 62 is composed of a triode Q2, a resistor R1 and a diode D1, and basically connected as follows: the base electrode of the triode Q2 is connected with one end of a resistor R1, the cathode of a diode D1 and the collector electrode of the triode Q3 in the driving circuit 61, the other end of the resistor R1 is connected with the collector electrode of the triode Q2, the source electrode S of the switching tube 2 and the input power supply end VIN, and the anode electrode of the diode D1 is connected with the emitter electrode of the triode Q2 and the grid electrode G of the switching tube 2;
the working process is as follows: the speed of the switching tube Q1 is accelerated when the switching tube Q1 is cut off, so that the loss is reduced, and the conversion efficiency is improved. The triode Q2 comprises a Darlington composite tube, or a composite tube formed by two triodes, or a single triode.
The start-up circuit 7:
the starting circuit 7 comprises a power-on starting circuit 71 and a low-voltage bias circuit 72.
The power-on starting circuit 71 is connected with an input power supply end VIN, a bias is provided for the triode Q3 in the driving circuit 61 at the power-on moment, the power-on starting circuit 71 fails due to the fact that two ends of the capacitor C5 are fully charged after starting, the bias of the triode Q3 in the driving circuit 61 is provided by the low-voltage bias circuit 72, and the low-voltage direct-current power supply end VCC is sent to the input end NET2 of the control circuit 6 through the diode D3 and the resistor R9.
The structure of the power-on starting circuit which is automatically disconnected after the power-on starting is finished and the low-voltage bias circuit 72 connected to the low-voltage direct-current end further widens the input voltage range and effectively reduces the loss.
Power-on start circuit 71:
the power-on starting circuit 71 is formed by connecting a resistor R3 and a capacitor C5 in series, one end of the capacitor C5 is connected with an input power supply end VIN and a source S of a switch tube Q1, the other end of the capacitor C5 is connected with one end of a resistor R3, the other end of the resistor R3 is connected with an input end NET2 of the control circuit 6, and the working process is as follows: after power-on, the voltage passes through the capacitor C5 and is limited by the starting resistor R3, and then is sent to the input end NET2 of the control circuit 6, that is, the transistor Q3 in the driving circuit 61 is turned on to drive the switching tube Q1 to be turned on. The switching tube Q1 turns on the subsequent current diode D2 to be turned off, and the input power source terminal VIN charges the energy storage inductor L1, and simultaneously provides energy to the filter capacitor C3 and the subsequent load.
Low voltage bias circuit 72:
the low-voltage bias circuit 72 is formed by connecting a resistor R9 and a diode D3 in series, one end of the resistor R9 is connected with an input end NET2 of the control circuit 6, the other end of the resistor R9 is connected with a cathode of a diode D3, and an anode of a diode D3 is connected with a low-voltage direct-current power supply end VCC.
Oscillation feedback circuit 8:
the oscillation feedback circuit 8 is formed by connecting a capacitor C2 and a resistor R5 in series, and the basic connection relationship is as follows: one end of a capacitor C2 is connected with the drain of a switch tube Q1, one end of an energy storage inductor L1 and the cathode of a freewheeling diode D2, the other end of the capacitor C2 is connected with a resistor R5, the other end of a resistor R5 is connected with the input end NET2 of the control circuit 6, the other end of the energy storage inductor L1 is connected with the anode of a filter capacitor C3 and a low-voltage direct-current power supply end VCC, and the cathode of the filter capacitor C3 and the anode of the freewheeling diode D2 are connected with a power supply common ground GND. The working process is as follows: after the switching tube Q1 is conducted, the output voltage of the switching tube Q1 is fed back to the input end NET2 of the control circuit 6 through the oscillation feedback circuit 5 to control the conduction of the switching tube Q1 through the triode Q3, when the capacitor C2 is fully charged, the triode Q3 is cut off, and the switching tube Q1 is cut off immediately; when the switching tube Q1 is turned off and the subsequent current diode D2 is turned on, the energy storage inductor L1 releases all the energy stored in the previous stage to the filter capacitor C3 and the subsequent load.
The comparison circuit 10:
the comparison circuit 10 includes a circuit composed of a triode, or a circuit composed of an operational amplifier chip, or a circuit composed of a comparator chip.
The specific embodiment is as follows:
the comparison circuit 10 comprises a transistor Q6 and a resistor R6, and is basically connected as follows: one end of the resistor R6 is connected with the base electrode of the triode Q6, the other end of the resistor R6 is connected with output signals of current sampling and voltage sampling, the emitter electrode of the triode Q6 is connected with the power supply common ground GND, and the collector electrode of the triode Q6, namely the output end of the comparison circuit 10, is connected with the input end NET2 of the control circuit;
the transistor Q6 comprises an NPN transistor or an N-channel field effect transistor.
Output voltage stabilizing circuit:
the output voltage stabilizing circuit is realized by a voltage sampling circuit and a comparison circuit, the voltage sampling circuit is formed by connecting a voltage stabilizing diode and a current limiting resistor in series or is formed by two divider resistors, the voltage sampling circuit is connected between an output voltage end and a grounding end, and a voltage sampling signal is taken out from a central contact of the voltage sampling circuit.
The specific embodiment is as follows:
the output voltage stabilizing circuit is realized by a voltage sampling circuit 12 and a comparison circuit 10, wherein the voltage sampling circuit 12 comprises a voltage stabilizing diode Z2 and a current limiting resistor R7 which are connected in series, and the basic connection relationship is as follows: the cathode of the zener diode Z2 is connected to the output voltage terminal VOUT, the anode of the zener diode Z2 and one end of the current limiting resistor R7 are connected to the input terminal of the comparator circuit 10, and the other end of the current limiting resistor R7 is connected to the power supply common ground GND.
The working process is as follows: when the direct current output voltage of the output voltage end VOUT is higher than the breakdown voltage-stabilizing value of the zener diode Z2, the direct current output voltage of the output voltage end VOUT obtains a sampling voltage signal on the current-limiting resistor, and the sampling voltage signal is output through the comparison circuit 10 and then sent to the input end NET2 of the control circuit 6, namely the base of the triode Q3 in the driving circuit 61, so that the triode Q3 is cut off, the switching tube Q1 is also cut off immediately, and after the switching tube Q1 is cut off, the direct current output voltage of the output voltage end VOUT immediately drops; z2 is cut off when the direct current output voltage of the output voltage end VOUT is lower than the voltage stabilization value of a voltage stabilizing diode Z2, the comparison circuit 10 outputs high level at the moment and sends the high level to the input end NET2 of the control circuit 6, namely, the base electrode of a triode Q3 in the driving circuit 61 enables the triode Q3 to be conducted, so that a driving switch tube Q1 is conducted, the direct current output voltage of the output voltage end VOUT rises, and the process is continuously and automatically repeated to realize the stability of the direct current output voltage.
The overcurrent protection circuit:
the overcurrent protection circuit is realized by a current sampling circuit and a comparison circuit, the current sampling circuit comprises a current sampling resistor, a triode and a biasing resistor, two ends of the current sampling resistor are respectively connected with an emitting electrode of the triode and one end of the biasing resistor, a base electrode of the triode is connected with the other end of the biasing resistor, and a collector electrode of the triode is connected with the input end of the comparison circuit; the transistor comprises a PNP transistor.
Furthermore, a capacitor can be connected between the base of the triode in the current sampling circuit and the power supply common ground GND.
The specific embodiment is as follows:
the overcurrent protection circuit is realized by a current sampling circuit 11 and a comparison circuit 10, wherein the current sampling circuit 11 comprises a current sampling resistor R8, a triode Q7 and a resistor R9, and the basic connection relation is as follows: one end of the resistor R8 is connected with one end of the energy storage inductor L1, a low-voltage direct current power supply end VCC and an emitting electrode of the triode Q7, the other end of the resistor R8 is connected with one end of the resistor R9 and an output voltage end VOUT, a base electrode of the triode Q7 is connected with the other end of the resistor R9, and a collector electrode of the triode Q7 is connected with an input end of the comparison circuit 10; the transistor Q7 comprises a PNP transistor.
Further, a capacitor C6 may be connected between the base of the transistor in the current sampling circuit and the power supply common ground GND.
The working process is as follows: when the output current is larger than a certain value, the voltage difference signal on the current sampling resistor R8 passes through the triode Q7 and the comparison circuit 10
The output high-low level is sent to the input end NET2 of the control circuit 6, namely, the base electrode of the triode Q3 in the driving circuit 61, so that the triode Q3 is cut off, the switching tube Q1 is also cut off immediately, and the direct current output voltage of the output voltage end VOUT is reduced immediately, which causes the output current to be correspondingly reduced.
The above description is only the specific embodiment of the preferred embodiment of the present invention, and is not intended to limit the present invention in any form, and although the present invention has been disclosed with the preferred embodiment, but not limited to the present invention, any skilled person familiar with the art can make some changes or modifications to equivalent embodiments with equivalent changes within the technical scope of the present invention, but all the technical essence (technical solution and its utility model concept) of the present invention is any simple modification, equivalent changes and modifications to the above embodiments, and still belongs to the technical scope of the present invention.
Claims (8)
1. BUCK converter circuit (1) comprising: the device comprises a switching tube (2), an energy storage inductor (3), a freewheeling diode (4), a filter capacitor (5) and a control circuit (6); a source electrode (S) of the switch tube (2) is connected with an input power supply end (VIN), a drain electrode (D) of the switch tube (2) is connected with one end of an energy storage inductor (3) and a cathode (K) of a fly-wheel diode (4), the other end of the energy storage inductor (3) is connected with a positive electrode end of a filter capacitor (5), an anode (A) of the fly-wheel diode (4) and a negative electrode of the filter capacitor (5) are connected with a power supply common Ground (GND), and an output end of a control circuit (6) is connected with a grid electrode (G) of the switch tube (2);
the method is characterized in that:
further comprising: the overvoltage protection device (9), the starting circuit (7) and the oscillation feedback circuit (8);
the control circuit (6) comprises a driving circuit (61) and an accelerating circuit (62);
the grounding end of the control circuit (6) is connected with a power supply common Ground (GND);
the input end (NET 2) of the control circuit (6) is connected with one end of the starting circuit (7) and one end of the oscillation feedback circuit (8), the power supply end of the control circuit (6) is connected with the source electrode (S) and the input power supply end (VIN) of the switch tube (2), the other end of the starting circuit (7) is connected with the input power supply end (VIN), the other end of the oscillation feedback circuit (8) is connected with the connection point (NET 1) of the switch tube (2) and the energy storage inductor (3), and two ends of the overvoltage protector (9) are connected in parallel between the grid electrode (G) and the source electrode (S) of the switch tube (2);
the switch tube (2) comprises a P-channel field effect tube or a PNP triode;
the freewheeling diode (4) comprises a fast recovery diode or a schottky diode;
the third end of the starting circuit (7) is connected with the rear-stage low-voltage direct-current output end;
the starting circuit (7) comprises a power-on starting circuit (71) and a low-voltage bias circuit (72);
the power-on starting circuit (71) is formed by connecting a resistor and a capacitor in series or only by the resistor, one end of the power-on starting circuit (71) is connected with an input end (NET 2) of the control circuit (6), and the other end of the power-on starting circuit (71) is connected with an input power supply end (VIN);
the low-voltage bias circuit (72) is formed by connecting a resistor (R9) and a diode (D3) in series or only by a resistor (R9), one end of the low-voltage bias circuit (72) is connected with the input end (NET 2) of the control circuit (6), and the other end of the low-voltage bias circuit (72) is connected with the rear-stage low-voltage direct-current output end;
the rear-stage low-voltage direct-current output end comprises a direct-current output voltage directly or indirectly from the filter capacitor (5);
the overvoltage protector (9) comprises a transient voltage suppressor TVS, or a voltage stabilizing diode, or a piezoresistor, or an ESD suppressor, or a ceramic gas discharge tube;
the driving circuit (61) comprises a constant current circuit formed by triodes, or a switching circuit formed by the triodes, or a switching circuit formed by field effect transistors;
the accelerating circuit (62) is composed of a triode, a resistor and a diode, or is only composed of a resistor;
the oscillation feedback circuit (8) is formed by connecting a resistor and a capacitor in series.
2. BUCK converter circuit (1) according to claim 1, characterized in that: the driving circuit (61) is composed of triodes (Q3, Q5) and a resistor (R2); basic connection relation: an emitter of a third triode (Q3) is connected with a base of a fifth triode (Q5) and one end of a second resistor (R2), an emitter of the fifth triode (Q5) and the other end of the second resistor (R2) are connected to a power supply common Ground (GND), a base of the third triode (Q3) is connected with a collector of the fifth triode (Q5), one end of a starting circuit (7), one end of a fifth resistor (R5) in an oscillation feedback circuit (8) and an output end of a comparison circuit (10), and a collector of the third triode (Q3) is connected with one end of a first resistor (R1) in an acceleration circuit (62), a base of a second triode (Q2) in the acceleration circuit (62) and a cathode of a first diode (D1) in the acceleration circuit (62);
the third triode (Q3) comprises a Darlington composite tube, or a composite tube formed by two triodes, or a single triode, or an N-channel field effect tube;
the fifth triode (Q5) comprises an NPN triode or an N-channel field effect transistor.
3. BUCK converter circuit (1) according to claim 1, characterized in that: the accelerating circuit (62) comprises a second triode (Q2), a first resistor (R1) and a first diode (D1); the basic connection relationship is as follows: the base electrode of the second triode (Q2) is connected with one end of the first resistor (R1), the cathode of the first diode (D1) and the collector electrode of the third triode (Q3) in the driving circuit (61), the other end of the first resistor (R1) is connected with the collector electrode of the second triode (Q2), the source electrode (S) of the switch tube (2) and the input power supply end (VIN), and the anode of the first diode (D1) is connected with the emitter electrode of the second triode (Q2) and the grid electrode (G) of the switch tube (2);
the triode (Q2) comprises a Darlington composite tube, or a composite tube formed by two triodes, or a single triode.
4. A dc voltage reducing device comprising the BUCK converter circuit (1) according to any of claims 1 to 3, further comprising: a current sampling circuit (11), a voltage sampling circuit (12), and a comparison circuit (10); a sampling resistor in the current sampling circuit (11) is connected in series between a low-voltage direct-current power supply end (VCC) and an output voltage end (VOUT) and is used for sampling the current of a rear-stage load, and a current sampling signal taken out from the output end of the current sampling circuit is connected with the input end of the comparison circuit (10); the voltage sampling circuit (12) is connected between the output voltage end (VOUT) and a power supply common ground GND, and a voltage sampling signal is taken out from a central joint of the voltage sampling circuit (12) and is sent to the input end of the comparison circuit (10).
5. The dc voltage dropping apparatus according to claim 4, wherein: the comparison circuit (10) comprises a circuit formed by triodes, or a circuit formed by an operational amplifier chip, or a circuit formed by a comparator chip.
6. The dc voltage dropping apparatus according to claim 4, wherein: the voltage sampling circuit (12) is formed by connecting a voltage stabilizing diode and a current limiting resistor in series or two voltage dividing resistors.
7. The dc voltage dropping apparatus according to claim 4, wherein: the current sampling circuit (11) comprises a current sampling resistor, a triode and a biasing resistor; two ends of the current sampling resistor are respectively connected with an emitting electrode of the triode and one end of the bias resistor, a base electrode of the triode is connected with the other end of the bias resistor, and a collector electrode of the triode is connected with an input end of a comparison circuit (10);
the transistor comprises a PNP transistor.
8. The dc voltage dropping apparatus according to claim 7, wherein: furthermore, the current sampling circuit also comprises a capacitor; and two ends of the capacitor are respectively connected between the base electrode of the triode in the current sampling circuit and the power supply common Ground (GND).
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112491267A (en) * | 2020-11-04 | 2021-03-12 | 深圳市崧盛电子股份有限公司 | Common-ground BUCK constant current driving circuit and multi-output switching power supply |
| CN114400897A (en) * | 2022-02-17 | 2022-04-26 | 深圳信息职业技术学院 | Self-excitation type Buck converter |
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2019
- 2019-10-28 CN CN201921818338.2U patent/CN210405090U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112491267A (en) * | 2020-11-04 | 2021-03-12 | 深圳市崧盛电子股份有限公司 | Common-ground BUCK constant current driving circuit and multi-output switching power supply |
| CN112491267B (en) * | 2020-11-04 | 2022-03-18 | 深圳市崧盛电子股份有限公司 | Common-ground BUCK constant current driving circuit and multi-output switching power supply |
| CN114400897A (en) * | 2022-02-17 | 2022-04-26 | 深圳信息职业技术学院 | Self-excitation type Buck converter |
| CN114400897B (en) * | 2022-02-17 | 2022-12-20 | 深圳信息职业技术学院 | Self-excitation type Buck converter |
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