CN112713770A - BUCK converter - Google Patents
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- CN112713770A CN112713770A CN202011545623.9A CN202011545623A CN112713770A CN 112713770 A CN112713770 A CN 112713770A CN 202011545623 A CN202011545623 A CN 202011545623A CN 112713770 A CN112713770 A CN 112713770A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
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Abstract
The invention provides a BUCK converter, wherein when the difference value of the input voltage minus the output voltage of a main circuit of the BUCK converter is less than or equal to a first preset voltage and is greater than zero, an auxiliary control circuit controls the voltage difference between two ends of an energy storage capacitor arranged between a collector of a switch tube and a charge pump to be the first preset voltage so as to maintain the output stability of the main circuit. That is, even if the voltage drop of the main circuit does not meet the condition, as long as the input voltage of the main circuit is greater than the output voltage, the output stability of the main circuit can be ensured, and the reliability of the BUCK converter is improved. And when the input voltage of the main circuit is less than or equal to the output voltage, the voltage difference between the energy storage capacitor and the two ends of the energy storage capacitor can be controlled to be a first preset voltage, and the output voltage of the main circuit is equal to the input voltage.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a BUCK converter.
Background
The DC-DC converter has advantages of outputting a stable voltage and having high efficiency, and is increasingly widely used in the fields of computers, automation or electronic instruments, and the like. A BUCK converter, also called BUCK converter, is a common kind of DC-DC converter, i.e. the output voltage is always smaller than the input voltage.
In the prior art, a schematic structural diagram of a BUCK converter is shown in fig. 1, and the operating principle is as follows: the charge pump is driven by a PWM (Pulse Width Modulation) signal output by the auxiliary control circuit, so that the on-off of the switching tube is controlled, and the harmonic component of the input voltage is inhibited from passing through by the voltage dividing resistor and the capacitor, namely the output voltage is the direct current component of the input voltage and then the micro ripple wave is added.
Due to the circuit characteristic requirements, a certain voltage drop is needed between the input voltage and the output voltage of the BUCK converter, so that stable output can be realized. That is, when the input voltage is greater than the set output voltage but the voltage drop is not satisfactory, the output voltage will appear jittering.
Disclosure of Invention
In view of this, embodiments of the present invention provide a BUCK converter to keep the output of the BUCK converter stable and improve the reliability of the BUCK converter when the voltage drop does not meet the requirement.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
the invention provides a BUCK converter, comprising: a main circuit and an auxiliary control circuit; wherein:
a charge pump is arranged at the base of the switching tube in the main circuit;
an energy storage capacitor is arranged between the collector of the switch tube and the charge pump;
a feedback circuit is arranged between the positive electrode and the negative electrode of the output end of the main circuit, and the feedback circuit outputs a feedback signal to the charge pump;
the auxiliary control circuit is used for controlling the voltage difference between two ends of the energy storage capacitor to be the first preset voltage when the difference value of the input voltage minus the output voltage of the main circuit is less than or equal to the first preset voltage and greater than zero so as to maintain the output stability of the main circuit.
Preferably, the auxiliary control circuit is further configured to:
and when the input voltage of the main circuit is less than or equal to the output voltage, controlling the voltage difference between two ends of the energy storage capacitor to be the first preset voltage so as to enable the output voltage of the main circuit to be equal to the input voltage.
Preferably, the auxiliary control circuit includes: an oscillation circuit, a booster circuit, and a linear amplification circuit;
the output end of the oscillating circuit is connected with the first input end of the booster circuit;
a second input end of the booster circuit is used as an input end of the auxiliary control circuit and is connected with the positive electrode of the output end of the main circuit;
the output end of the booster circuit is connected with the first input end of the linear amplification circuit;
the connection point of the collector of the switching tube and the energy storage capacitor is connected with the second input end of the linear amplification circuit;
and the output end of the linear amplification circuit is used as the output end of the auxiliary control circuit and is connected with the connection point of the energy storage capacitor and the charge pump.
Preferably, the oscillating circuit is configured to output a PWM signal to the first input terminal of the voltage boost circuit.
Preferably, the oscillation circuit includes: the circuit comprises a first capacitor, a first resistor and a Schmitt trigger; wherein:
the first resistor is connected between the input end and the output end of the Schmitt trigger;
the input end of the Schmitt trigger is grounded through the first capacitor, and the output end of the Schmitt trigger serves as the output end of the oscillating circuit and outputs a square wave signal to the first input end of the booster circuit.
Preferably, the boost circuit is configured to output a second preset voltage to the first input terminal of the linear amplification circuit.
Preferably, the booster circuit includes: first to fourth diodes and second to fifth capacitors; wherein:
the anode of the fourth diode is used as the second input end of the booster circuit;
the cathode of the fourth diode is connected with the anode of the third diode, and the connecting point is connected with one end of the second capacitor;
the cathode of the third diode is connected with the anode of the second diode, and the connecting point is connected with one end of the fifth capacitor;
the cathode of the second diode is connected with the anode of the first diode, and the connecting point is connected with one end of the third capacitor;
the cathode of the first diode is connected with one end of the fourth capacitor, and the connection point is used as the output end of the booster circuit;
the other end of the second capacitor is connected with the other end of the third capacitor, and a connection point is used as a first input end of the booster circuit;
the other end of the fourth capacitor and the other end of the fifth capacitor are both grounded.
Preferably, the second preset voltage is: the output voltage of the main circuit subtracts the voltage drop of the two diodes, and subtracts the preset loss voltage value of the switching tube after adding twice of the high level voltage value output by the oscillation circuit.
Preferably, the linear amplification circuit includes: the voltage regulator tube, the triode and the second resistor; wherein:
the base electrode of the triode is connected with one end of the second resistor and the cathode of the voltage stabilizing tube;
the collector of the triode is connected with the other end of the second resistor, and the connection point is used as the first input end of the linear amplification circuit;
the anode of the voltage-stabilizing tube is used as a second input end of the linear amplifying circuit;
and the emitter of the triode is used as the output end of the linear amplification circuit.
Preferably, the first preset voltage is: and the voltage drop between the base electrode and the collector electrode of the triode is subtracted from the voltage stabilizing value of the voltage stabilizing tube.
Based on the BUCK converter provided by the embodiment of the invention, when the difference between the input voltage and the output voltage of the main circuit is less than or equal to the first preset voltage and greater than zero, the auxiliary control circuit controls the voltage difference between the collector of the switching tube and the energy storage capacitor between the charge pumps to be the first preset voltage so as to maintain the output stability of the main circuit. That is, even if the voltage drop of the main circuit does not meet the condition, as long as the input voltage of the main circuit is greater than the output voltage, the output stability of the main circuit can be ensured, and the reliability of the BUCK converter is improved. And when the input voltage of the main circuit is less than or equal to the output voltage, the voltage difference between the energy storage capacitor and the two ends of the energy storage capacitor can be controlled to be a first preset voltage, and the output voltage of the main circuit is equal to the input voltage.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic diagram of a BUCK converter in the prior art;
FIG. 2 is an equivalent circuit diagram of a prior art BUCK converter with a switch tube turned on;
FIG. 3 is an equivalent circuit diagram of a prior art BUCK converter with the switch tube turned off;
FIG. 4 is a graph of the output voltage waveform of a prior art BUCK converter;
FIG. 5 is a schematic structural diagram of a BUCK converter according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of an auxiliary control circuit of the BUCK converter according to the embodiment of the present invention;
FIG. 7 is a schematic diagram of an oscillating circuit in an auxiliary control circuit of the BUCK converter according to the embodiment of the present invention;
FIG. 8 is a schematic diagram of a boost circuit in an auxiliary control circuit of the BUCK converter according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of a linear amplifier circuit in an auxiliary control circuit of the BUCK converter according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of a specific structure of a BUCK converter according to an embodiment of the present invention;
FIG. 11 is a waveform diagram of the output of the Schmitt trigger of the oscillating circuit in the auxiliary control circuit of the BUCK converter according to the embodiment of the present invention;
fig. 12 is a diagram of voltage waveforms of a boost circuit in an auxiliary control circuit of a BUCK converter according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
In the prior art, a schematic structural diagram of a BUCK converter is shown in fig. 1, and the operating principle is as follows: the on and off of the switching tube is controlled by a driving pulse signal output by the control circuit, when the pulse outputs a high level, the switching tube is on, an equivalent diagram is shown in fig. 2, at the moment, the voltage at two ends of the diode is equal to the output voltage Vout, and therefore the diode is in a reverse cut-off state; the current flows to the output end of the BUCK converter after flowing through the inductor, the current in the inductor gradually rises, self-induction potentials with positive left end and negative right end are generated at the two ends of the inductor to block the rise of the current, and the inductor converts the electric energy into magnetic energy for storage. After a period of time, the pulse changes to low level, the switching tube is turned off, the equivalent diagram is shown in fig. 3, but the current in the inductor cannot change suddenly, and at this time, the self-inductance potential at the two ends of the inductor prevents the current from decreasing, so that the diode is conducted in the forward direction, the current in the inductor forms a loop through the diode, the current value gradually decreases, and the magnetic energy stored in the inductor is converted into electric energy to be released. And repeating the process of switching on and switching off the switching tube.
Therefore, the operating characteristics of the BUCK converter require a certain voltage drop between the input voltage Vin and the output voltage Vout, and particularly, when Vin-Vout is greater than 1.5V, the BUCK converter can stably output. For example, if the BUCK converter requires 12V output, the input voltage Vin must be 13.5V or higher, and if the input voltage is 12V, it cannot be satisfied. The reason is that when Vin-Vout <1.5V, or Vin is lower than Vout set value, Vout shows jittered waveform, and the waveform diagram is shown in FIG. 4, i.e. BUCK converter output voltage can not be kept stable.
For the above problems, in the prior art, the input/output voltage drop can only be further reduced by using a better chip to replace the chip, but this undoubtedly increases the system cost greatly, and the problem of large voltage drop cannot be solved well, and output jitter still exists.
Therefore, the embodiment of the invention provides the BUCK converter, so that when the voltage drop does not meet the requirement, the output of the BUCK converter is kept stable, and the reliability of the BUCK converter is improved.
Specifically, a schematic structural diagram of the BUCK converter is shown in fig. 5, and includes: a main circuit 110 and an auxiliary control circuit 120; wherein:
the connection structure of the main circuit 110 is the same as the prior art, and as shown in fig. 1, a charge pump is arranged at the base of the switching tube Q2; an energy storage capacitor C6 is arranged between the collector of the switching tube Q2 and the charge pump; a feedback circuit (including two voltage dividing resistors connected in series) is disposed between the positive and negative terminals of the output end of the main circuit 110, and the feedback circuit outputs a feedback signal (shown as FB in fig. 5) to the charge pump.
The auxiliary control circuit 120 is configured to control a voltage difference across the energy storage capacitor C6 to be a first preset voltage when a difference between the input voltage and the output voltage of the main circuit 110 is less than or equal to the first preset voltage and greater than zero, so as to maintain the output of the main circuit 110 stable.
The schematic structural diagram of the auxiliary control circuit 120 is shown in fig. 6, and includes: an oscillation circuit 210, a booster circuit 220, and a linear amplifier circuit 230; the specific connection mode is as follows:
the output end of the oscillating circuit 210 is connected with the first input end of the boosting circuit 220; a second input end of the voltage boost circuit 220 is used as an input end of the auxiliary control circuit 120 and is connected with the positive pole of the output end of the main circuit 110; the output terminal of the voltage boost circuit 220 is connected to the first input terminal of the linear amplification circuit 230; the junction point of the collector of the switching tube Q2 and the energy storage capacitor C6 (as shown at V2 in fig. 6) is connected to the second input terminal of the linear amplification circuit 230; the output of the linear amplification circuit 230, which serves as the output of the auxiliary control circuit 120, is connected to the junction of the energy storage capacitor C6 and the charge pump (as shown at V1 in fig. 6).
Specifically, the schematic structural diagrams of the circuits in the auxiliary control circuit 120 are shown in fig. 7 to 9:
the oscillation circuit 210: the schematic structural diagram is shown in fig. 7, and includes: a first capacitor C1, a first resistor R1 and a Schmitt trigger U1; wherein:
the first resistor R1 is connected between the input end and the output end of the Schmitt trigger U1; the input terminal of the schmitt trigger U1 is grounded through the first capacitor C1, and the output terminal of the schmitt trigger U1 serves as the output terminal of the oscillating circuit 210, and outputs a square wave signal to the first input terminal of the voltage boosting circuit 220. Note that the schmitt trigger U1 is a comparator circuit including positive feedback, in which the internal oscillation signal of the schmitt trigger U1 is a sine wave, and the output signal of the oscillator circuit 210 is a square wave, and the waveform diagram thereof is as shown in fig. 11.
In practical applications, the oscillation circuit 210 is configured to generate a PWM (Pulse Width Modulation) signal to the first input terminal of the voltage boost circuit 220, that is, the output signal of the oscillation circuit 210 and the output voltage Vout of the main circuit 110 jointly act on the voltage boost circuit 220 to drive the voltage boost circuit 220, so that the output voltage rises to a second preset voltage.
The booster circuit 220: the schematic diagram of the structure is shown in fig. 8, and the function is to output a second preset voltage to the first input terminal of the linear amplifying circuit 230 so as to further act on the main circuit 110; the booster circuit 220 includes: a first diode D1 through a fourth diode D4 and a second capacitor C2 through a fifth capacitor C5; wherein:
the anode of the fourth diode D4 serves as the second input terminal of the voltage boost circuit 220; the cathode of the fourth diode D4 is connected with the anode of the third diode D3, and the connection point is connected with one end of the second capacitor C2; the cathode of the third diode D3 is connected with the anode of the second diode D2, and the connection point is connected with one end of the fifth capacitor C5; the cathode of the second diode D2 is connected with the anode of the first diode D1, and the connection point is connected with one end of the third capacitor C3; the cathode of the first diode D1 is connected to one end of the fourth capacitor C4, and the connection point is used as the output end of the voltage boost circuit 220; the other end of the second capacitor C2 is connected to the other end of the third capacitor C3, and the connection point is used as the first input end of the voltage boost circuit 220; the other end of the fourth capacitor C4 and the other end of the fifth capacitor C5 are both grounded.
As can be seen from the schematic structural diagrams of the oscillating circuit 210 and the voltage boost circuit 220 shown in fig. 7 and fig. 8, the magnitude of the second preset voltage output by the voltage boost circuit 220 is related to the output voltage Vout, and specifically, the second preset voltage is: the voltage drop of the two diodes is subtracted from the output voltage of the main circuit 110, and the voltage value is added to twice the high level voltage value output by the oscillating circuit 210, and then the preset loss voltage value of the switching tube is subtracted.
For example, the output square wave signal of the oscillating circuit 210 is divided into a high level and a low level, and the high level is assumed to be 5V. If the output square wave signal acts on the second capacitor C2 of the voltage boost circuit 220, and the second capacitor C2 does not have sudden change, the voltage value at the connection point of the second capacitor C2 and the fourth diode D4 is Vout-0.7V if the output square wave signal is 0V; if the output square wave signal is 5V, the energy of C2 and D4 is ensured not to flow to Vout but to D3 due to the unidirectional conductivity of the diodes, and the fifth capacitor C5 plays a role of storing energy, so that the voltage is smoother, and at this time, the voltage at the connection point of the third diode D3 and the fourth diode D4 is Vout-0.7+5V, that is, about Vout + 4.3V. Similarly, if a square wave signal is output to the third capacitor C3, the voltage is about Vout + 8.6V; however, since there is a certain loss of energy during switching, the second preset voltage output by the boost circuit 220 is about Vout +8V, and the output voltage waveform at each point is as shown in fig. 12.
The linear amplifier circuit 230 is equivalent to a small-sized voltage regulator, and the structure diagram thereof is shown in fig. 9, which includes: a voltage regulator tube T1, a triode Q1 and a second resistor R2; wherein:
the base electrode of the triode T1 is connected with one end of the second resistor R2 and the cathode of the voltage regulator tube T1; the collector of the transistor Q1 is connected to the other end of the second resistor R2, and the connection point is used as the first input end of the linear amplifying circuit 230; the anode of the voltage regulator tube T1 is used as the second input end of the linear amplifying circuit 230; the emitter of the transistor Q1 serves as the output of the linear amplification circuit 230.
The specific operation principle of the linear amplification circuit 230 is as follows: assuming that the voltage stabilizing value of the voltage stabilizing tube is Vz, and because 0.6V voltage drop exists between the base electrode and the collector electrode of the triode Q1, the output voltage is the base electrode voltage + Vz-0.6V of the switch tube Q2, namely V1+ Vz-0.6V, and acts on the collector electrode (namely V2) of the switch tube Q2; therefore, the auxiliary control circuit 120 controls the voltage difference (i.e., V2-V1) across the energy storage capacitor C6 (as shown at V1 and V2 in fig. 10) to be the first preset voltage, i.e., controls the voltage difference across the energy storage capacitor C6 to be maintained at Vz-0.6V. It should be noted that the regulated value Vz of the regulator tube is selected with reference to the voltage of V1, and is not limited herein.
Referring to the schematic structural diagrams shown in fig. 6 to 9, a detailed structural diagram of the BUCK converter according to the embodiment of the present invention is shown in fig. 10, wherein the auxiliary control circuit 120 does not function when the difference between the input voltage and the output voltage of the main circuit 110 is greater than the first predetermined voltage, i.e., Vin > Vout + Vz-0.6V; if the difference between the input voltage and the output voltage of the main circuit 110 is less than or equal to the first predetermined voltage and greater than zero, i.e., Vout < Vin ≦ Vout + Vz-0.6V, the auxiliary control circuit 120 boosts the voltage waveform of V2, so that the voltage drop between V2 and V1 is maintained at about Vz-0.6V, which can ensure that the output waveform of the main circuit 110 does not jitter and remains stable. Therefore, the BUCK converter provided by the embodiment of the invention can maintain the output stability of the BUCK converter as long as the input voltage of the BUCK converter is greater than the output voltage without the 1.5V voltage drop between the input and the output of the BUCK converter.
It should be noted that even when the input voltage of the main circuit 110 is less than or equal to the output voltage, the auxiliary control circuit 120 can still control the voltage difference across the energy storage capacitor C6 to be the first preset voltage, although the output voltage of the auxiliary control circuit will drop with the drop of the input voltage due to the limitation of the topology of the converter and cannot reach the set value, the auxiliary control circuit 120 can provide sufficient energy for the charge pump, and control the switch Q2 to be fully turned on, so that the output voltage of the main circuit 110 is equal to the input voltage and keeps a straight line, that is, the output voltage waveform does not appear jitter, and stable energy can be provided.
To sum up, in the BUCK converter provided in the embodiment of the present invention, the boost circuit 220 is equivalent to an external charge pump, and the linear amplification circuit 230 is a small voltage regulator, so that the application space of the BUCK converter is widened, and only minor hardware changes are performed, which does not greatly increase the system cost, and thus, the problems of large voltage drop and voltage jitter of the BUCK converter in the prior art can be solved, the reliability of the BUCK converter is improved, and the BUCK converter has practical significance.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A BUCK converter, comprising: a main circuit and an auxiliary control circuit; wherein:
a charge pump is arranged at the base of the switching tube in the main circuit;
an energy storage capacitor is arranged between the collector of the switch tube and the charge pump;
a feedback circuit is arranged between the positive electrode and the negative electrode of the output end of the main circuit, and the feedback circuit outputs a feedback signal to the charge pump;
the auxiliary control circuit is used for controlling the voltage difference between two ends of the energy storage capacitor to be the first preset voltage when the difference value of the input voltage minus the output voltage of the main circuit is less than or equal to the first preset voltage and greater than zero so as to maintain the output stability of the main circuit.
2. The BUCK converter according to claim 1, wherein the auxiliary control circuit is further configured to:
and when the input voltage of the main circuit is less than or equal to the output voltage, controlling the voltage difference between two ends of the energy storage capacitor to be the first preset voltage so as to enable the output voltage of the main circuit to be equal to the input voltage.
3. BUCK converter according to claim 1 or 2, characterized in that said auxiliary control circuit comprises: an oscillation circuit, a booster circuit, and a linear amplification circuit;
the output end of the oscillating circuit is connected with the first input end of the booster circuit;
a second input end of the booster circuit is used as an input end of the auxiliary control circuit and is connected with the positive electrode of the output end of the main circuit;
the output end of the booster circuit is connected with the first input end of the linear amplification circuit;
the connection point of the collector of the switching tube and the energy storage capacitor is connected with the second input end of the linear amplification circuit;
and the output end of the linear amplification circuit is used as the output end of the auxiliary control circuit and is connected with the connection point of the energy storage capacitor and the charge pump.
4. The BUCK converter according to claim 3, wherein the oscillation circuit is configured to output a PWM signal to the first input terminal of the boost circuit.
5. The BUCK converter according to claim 4, wherein the oscillation circuit includes: the circuit comprises a first capacitor, a first resistor and a Schmitt trigger; wherein:
the first resistor is connected between the input end and the output end of the Schmitt trigger;
the input end of the Schmitt trigger is grounded through the first capacitor, and the output end of the Schmitt trigger serves as the output end of the oscillating circuit and outputs a square wave signal to the first input end of the booster circuit.
6. The BUCK converter according to claim 3, wherein the boost circuit is configured to output a second predetermined voltage to the first input of the linear amplification circuit.
7. The BUCK converter according to claim 6, wherein the boost circuit includes: first to fourth diodes and second to fifth capacitors; wherein:
the anode of the fourth diode is used as the second input end of the booster circuit;
the cathode of the fourth diode is connected with the anode of the third diode, and the connecting point is connected with one end of the second capacitor;
the cathode of the third diode is connected with the anode of the second diode, and the connecting point is connected with one end of the fifth capacitor;
the cathode of the second diode is connected with the anode of the first diode, and the connecting point is connected with one end of the third capacitor;
the cathode of the first diode is connected with one end of the fourth capacitor, and the connection point is used as the output end of the booster circuit;
the other end of the second capacitor is connected with the other end of the third capacitor, and a connection point is used as a first input end of the booster circuit;
the other end of the fourth capacitor and the other end of the fifth capacitor are both grounded.
8. The BUCK converter according to claim 7, wherein the second preset voltage is: the output voltage of the main circuit subtracts the voltage drop of the two diodes, and subtracts the preset loss voltage value of the switching tube after adding twice of the high level voltage value output by the oscillation circuit.
9. The BUCK converter according to claim 3, wherein the linear amplification circuit includes: the voltage regulator tube, the triode and the second resistor; wherein:
the base electrode of the triode is connected with one end of the second resistor and the cathode of the voltage stabilizing tube;
the collector of the triode is connected with the other end of the second resistor, and the connection point is used as the first input end of the linear amplification circuit;
the anode of the voltage-stabilizing tube is used as a second input end of the linear amplifying circuit;
and the emitter of the triode is used as the output end of the linear amplification circuit.
10. The BUCK converter according to claim 9, wherein the first predetermined voltage is: and the voltage drop between the base electrode and the collector electrode of the triode is subtracted from the voltage stabilizing value of the voltage stabilizing tube.
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| CN202011545623.9A CN112713770B (en) | 2020-12-24 | 2020-12-24 | BUCK converter |
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| CN202011545623.9A CN112713770B (en) | 2020-12-24 | 2020-12-24 | BUCK converter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110299842A (en) * | 2019-07-23 | 2019-10-01 | 东莞保力电子有限公司 | A kind of pressurization afterflow low voltage difference Buck type switching power unit |
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| CN112713770B (en) | 2022-04-05 |
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