CN114649958B - Switching power supply and charger - Google Patents
Switching power supply and charger Download PDFInfo
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- CN114649958B CN114649958B CN202210549633.2A CN202210549633A CN114649958B CN 114649958 B CN114649958 B CN 114649958B CN 202210549633 A CN202210549633 A CN 202210549633A CN 114649958 B CN114649958 B CN 114649958B
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- 238000001514 detection method Methods 0.000 claims abstract description 20
- 238000005070 sampling Methods 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 9
- 239000003990 capacitor Substances 0.000 claims description 7
- 230000003071 parasitic effect Effects 0.000 claims description 6
- 238000002955 isolation Methods 0.000 claims description 4
- 101100339482 Colletotrichum orbiculare (strain 104-T / ATCC 96160 / CBS 514.97 / LARS 414 / MAFF 240422) HOG1 gene Proteins 0.000 description 16
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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
- H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
- H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
- H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
- H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from AC mains by converters
- H02J7/04—Regulation of charging current or voltage
- H02J7/06—Regulation of charging current or voltage using discharge tubes or semiconductor devices
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
- H02M1/092—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices the control signals being transmitted optically
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- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The embodiment of the application discloses switching power supply and charger, switching power supply includes: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the valley bottom detection circuit is connected with the valley bottom judgment circuit, the PWM circuit and the control circuit, and the valley bottom judgment circuit is connected with the OSC circuit and the PWM circuit; the transformer comprises an auxiliary winding, a primary winding and a secondary winding, and the auxiliary winding is connected with the valley bottom detection circuit; the primary winding is connected with an external power supply and a first switching tube; the secondary winding is connected with a first diode, and the first diode is connected to a load; the PWM circuit is connected with one end of the first switch tube and the sampling resistor and the other end of the sampling resistor is grounded, and the PWM circuit is connected with a primary optocoupler in the feedback circuit and the other end of the primary optocoupler is grounded. By adopting the embodiment of the application, valley bottom number locking of the switching power supply can be realized.
Description
Technical Field
The application relates to the technical field of electronics, in particular to a switching power supply and a charger.
Background
Currently, electronic devices (such as mobile phones) can be charged by using a USB charger, and a switching power supply is an important component of the USB charger, which usually employs a maximum frequency clamp to limit the operating frequency range of the switching power supply in practice. However, when the operating frequency of the switching power supply is near the maximum clamp frequency, the switching power supply typically jumps between two or even more valleys, which may cause the operating frequency of the switching power supply to fluctuate dramatically, affecting loop stability and producing audible noise.
Disclosure of Invention
The embodiment of the application provides a switching power supply and a charger, which not only limits the maximum working frequency of the switching power supply, but also realizes valley bottom number locking of the switching power supply, and further improves the working stability of the switching power supply.
In a first aspect, an embodiment of the present application provides a switching power supply, where the switching power supply includes: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the detection circuit comprises a valley bottom detection circuit, a valley bottom judgment circuit, an OSC circuit and a PWM circuit, wherein the valley bottom detection circuit is connected with the valley bottom judgment circuit, the PWM circuit and a first pin of the control circuit, the valley bottom judgment circuit is connected with the OSC circuit and the PWM circuit, the PWM circuit is connected with a second pin, a third pin and a fourth pin of the control circuit, and the OSC circuit is connected with a fourth pin of the control circuit;
the transformer comprises an auxiliary winding, a primary winding and a secondary winding, wherein one end of the auxiliary winding is connected with the first pin, and the other end of the auxiliary winding is grounded; one end of the primary winding is connected with an external power supply, and the other end of the primary winding is connected with the first end of the first switching tube; one end of the secondary winding is connected with the anode of the first diode, and the other end of the secondary winding is grounded; the cathode of the first diode is connected with a load;
the PWM circuit is connected with the second end of the first switch tube through the second pin, and the PWM circuit is connected with the third end of the first switch tube, one end of the sampling resistor and the other end of the sampling resistor through the third pin and is grounded;
the feedback circuit realizes the isolation of the primary and secondary stages through the optical coupler, and one end of the primary optical coupler is connected with the fourth pin of the control circuit and the other end of the primary optical coupler is grounded.
In a second aspect, embodiments of the present application provide a charger including a switching power supply as described in the first aspect.
The embodiment of the application has the following beneficial effects:
it can be seen that the switching power supply and the charger described in the embodiments of the present application, wherein the switching power supply includes: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the valley bottom detection circuit is connected with the valley bottom judgment circuit, the PWM circuit and a first pin of the control circuit, the valley bottom judgment circuit is connected with the OSC circuit and the PWM circuit, and the PWM circuit is connected with a second pin and a third pin of the control circuit; the transformer comprises an auxiliary winding, a primary winding and a secondary winding, wherein one end of the auxiliary winding is connected with the first pin, and the other end of the auxiliary winding is grounded; one end of the primary winding is connected with an external power supply, and the other end of the primary winding is connected with the first end of the first switching tube; one end of the secondary winding is connected with the anode of the first diode and the other end of the secondary winding is grounded; the cathode of the first diode is connected with a load; the PWM circuit is connected with the second end of the first switch tube through the second pin, the PWM circuit is connected with the third end of the first switch tube through the third pin and is grounded through the sampling resistor, the maximum working frequency of the switch power supply is limited, valley bottom number locking of the switch power supply is achieved, and working stability of the switch power supply is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application 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 some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a switching power supply according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of another switching power supply provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of a switching tube according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a valley bottom determining circuit according to an embodiment of the present disclosure;
fig. 5 is a schematic waveform diagram in operation according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.
The terms "first," "second," and the like in the description and claims of the present application and in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
The following describes embodiments of the present application in detail.
In the related art, the operating frequency of the switching power supply operating in the resonant mode (QR) is inversely proportional to the load, please refer to fig. 1, where fig. 1 is a related art switching power supply including a control circuit including a valley detection circuit, an Oscillator (OSC), and a Pulse Width Modulation (PWM). The valley bottom detection circuit can be used for realizing valley bottom conduction of the switching power supply, the OSC can be used for limiting the maximum working frequency of the switching power supply according to the voltage of the FB pin, and the PWM circuit is used for generating PWM pulses for driving the switching tube.
The oscillator may also be referred to as an OSC circuit, and the pulse width modulation circuit may also be referred to as a PWM circuit.
In particular implementations, using this approach alone, the switching power supply typically jumps between two or even more valleys when the operating frequency is near the maximum clamp frequency, which can cause the operating frequency of the switching power supply to fluctuate dramatically, affecting loop stability and producing audible noise.
To solve the above-mentioned drawback, please refer to fig. 2, fig. 2 is a schematic structural diagram of a switching power supply according to an embodiment of the present application, and as shown in the drawing, the switching power supply according to the embodiment of the present application includes: control circuit, transformer, first switch tube Q 1 A first diode D 1 The control circuit comprises: the detection circuit comprises a valley bottom detection circuit, a valley bottom judgment circuit, an OSC circuit and a PWM circuit, wherein the valley bottom detection circuit is connected with the valley bottom judgment circuit, the PWM circuit and a first pin VS of the control circuit, the valley bottom judgment circuit is connected with the OSC circuit and the PWM circuit, the PWM circuit is connected with a second pin VG, a third pin CS and a fourth pin FB of the control circuit, and the OSC circuit is connected with the fourth pin FB of the control circuit;
the transformer comprises an auxiliary winding, a primary winding and a secondary winding, wherein one end of the auxiliary winding is connected with the first pin, and the other end of the auxiliary winding is grounded; one end of the primary winding is connected with an external power supply, and the other end of the primary winding is connected with the first switching tube Q 1 The first end of (a); one end of the secondary winding is connected with the first diode D 1 The anode and the other end of the anode are grounded; the first diode D 1 The cathode of (2) being connected to the load, i.e. via V out Connecting a load; the PWM circuit is connected with the first switching tube Q through the second pin VG 1 The PWM circuit is connected to the first switching tube Q through the third pin CS 1 Third terminal and sampling resistor R sense And a sampling resistor R sense And the other end of the same is grounded.
The feedback circuit realizes the isolation of a primary side and a secondary side through an optical coupler, one end of the primary optical coupler Opto is connected with a fourth pin FB of the control circuit, the other end of the primary optical coupler Opto is grounded, the feedback circuit transmits a load feedback signal, namely the voltage of the fourth pin FB, to the OSC circuit and the PWM circuit through the primary optical coupler Opto, the OSC circuit generates a corresponding frequency signal according to the voltage of the fourth pin FB, and the PWM circuit obtains a feedback voltage corresponding to a third pin CS according to the voltage of the fourth pin FB.
The feedback circuit further comprises a secondary optical coupler Opto, and one end of the secondary optical coupler Opto passes through the first resistor R 1 Connecting a first diode D 1 The other end of the secondary optical coupler Opto is grounded through a precision reference source TL431, and the feedback circuit passes through the precision reference source TL431 and a third resistor R 3 And a fourth resistor R 4 A third resistor R for realizing voltage stabilization 3 One end is connected with a fourth resistor R 4 And the other end is grounded, a fourth resistor R 4 Is connected with a first diode D 1 In addition, a second resistor R 2 The two ends of the secondary optical coupler Opto are connected in parallel, and one end of the secondary optical coupler Opto passes through the compensation component and passes through the third resistor R 3 The compensating component comprising a resistor R connected in series to ground comp And a capacitor C comp . The feedback circuit realizes the primary and secondary feedback functions through the optocoupler.
The first pin VG is used for driving the first switch tube Q 1 The second pin VS is used for detecting the voltage change of the auxiliary winding, the third pin CS is used for detecting the current flowing through the first switching tube Q1, and the fourth pin FB is used for detecting the voltage of the primary optocoupler of the feedback circuit.
In a specific implementation, the higher the input voltage of the OSC circuit, i.e., the higher the FB voltage of the fourth pin, the faster the frequency.
In the specific implementation, the homonymous end of the auxiliary winding is connected with the first pin VS, and the heteronymous end of the auxiliary winding is grounded; the dotted end of the primary winding is connected with a first switch tube Q 1 The synonym end of the primary winding is connected with an external power supply; the same-name end of the secondary winding is connected with the anode of the first diode, and the different-name end of the secondary winding is grounded.
Optionally, the first switch tube includes an NMOS tube and a parasitic diode, or the first switch tube includes an NMOS tube.
In a specific implementation, as shown in fig. 3, the first switch tube Q 1 May include an NMOS transistor and a parasitic diode, a first switch transistor Q 1 A parasitic diode is connected between the first terminal and the third terminal. First switch tube Q 1 The first terminal of (1) is a drain electrode, the second terminal is a grid electrode and the third terminal is a source electrode. The positive pole of the parasitic diode is connected with the first switch tube Q 1 The negative pole of the parasitic diode is connected with the first switch tube Q 1 The first end of (a).
Of course, the first switch tube Q 1 The transistor can also be composed of only one NMOS transistor, wherein the first end of the NMOS transistor is a drain electrode, the second end of the NMOS transistor is a grid electrode, and the third end of the NMOS transistor is a source electrode.
Optionally, the external power supply is grounded through a first capacitor, and the first diode is grounded through a second capacitor.
Wherein the external power supply V in Through the first capacitor C in Ground, the first diode D 1 Through a second capacitor C o And (4) grounding.
Optionally, the valley bottom detection circuit is configured to detect a valley bottom in a working process of the switching power supply, generate a valley bottom signal, and transmit the valley bottom signal to the valley bottom determination circuit and the PWM circuit;
the OSC circuit is used for generating a first frequency signal and a second frequency signal according to the voltage of the fourth pin FB after the switching tube is switched on every time, and transmitting the first frequency signal and the second frequency signal to the valley bottom judging circuit;
the valley bottom judging circuit is used for generating an enable signal according to the first frequency signal, the second frequency signal and the valley bottom signal and transmitting the enable signal to the PWM circuit;
the PWM circuit is configured to generate a PWM pulse for driving a switching tube according to the enable signal, the valley signal, the voltage of the third pin CS, and the voltage of the fourth pin FB, where the PWM pulse is used to control the first power tube to generate an output voltage.
In specific implementation, the Valley bottom detection circuit may be configured to detect a Valley bottom during a working process of the switching power supply and generate a Valley bottom signal Valley, and then transmit the generated Valley bottom signal to the PWM circuit and the Valley bottom determination circuit.
In addition, the OSC circuit can be used to generate two clamp frequency signals according to the FB voltage of the fourth pin after each switching on of the switching tube: the first frequency signal OSC1 and the second frequency signal OSC2, and further transmit the clamp frequency signals OSC1 and OSC2 to the valley bottom determination circuit; the two clamp frequency signals OSC1 and OSC2 can be used to limit the maximum operating frequency of the switching power supply according to the load feedback information, i.e., the FB voltage of the fourth pin.
The valley bottom judging circuit can be used for generating an enable signal EN and transmitting the enable signal EN to the PWM circuit. The valley bottom judging circuit can combine two clamping frequency signals OSC1 and OSC2 with the valley bottom number of the switching power supply in the working process to output an enable EN signal, the enable EN signal is used for enabling the PWM circuit to output high-level pulses when the valley bottom arrives, and the enable EN signal limits the maximum working frequency of the switching power supply.
In one embodiment, the PWM circuit is used for generating PWM pulses for driving the switching tube, and the PWM pulses are used for controlling a main power tube, i.e. the first switching tube Q 1 To generate an output voltage. When the enable signal EN of the valley bottom judging circuit received by the PWM circuit is high, the PWM circuit outputs a high-level pulse immediately when the valley bottom signal comes.
Optionally, the PWM circuit is configured to output a high level pulse immediately when the valley bottom signal arrives when the enable signal is high;
in specific implementation, when the enable signal EN of the valley bottom determining circuit received by the PWM circuit is high, the PWM circuit outputs a high level pulse immediately when the valley bottom signal arrives.
Optionally, the PWM circuit is configured to immediately output a low level pulse when the voltage sampled at the third pin reaches the feedback voltage corresponding to the fourth pin.
In a specific implementation, when the voltage sampled by the PWM circuit at the third pin CS reaches the feedback voltage corresponding to the fourth pin FB, the PWM circuit immediately outputs a low level pulse.
Optionally, the valley bottom determining circuit includes: the circuit comprises a counter, a data register, a comparator, an AND gate circuit and an OR gate circuit;
the counter is used for clearing and counting the valley bottom number in each switching period when each switching period is started;
the data register is used for updating and keeping a value obtained by subtracting one from the valley bottom number of the previous period into the data register at the beginning of each switching period;
the comparator is used for comparing the first value in the counter with the second value in the data register to obtain a comparison result;
the AND gate circuit is used for carrying out logical AND operation according to the comparison result and the first frequency signal to obtain a first operation result;
and the OR gate circuit is used for carrying out logical OR operation according to the second frequency signal and the first operation result to obtain a second operation result, and generating the enable signal according to the second operation result.
In a specific implementation, as shown in fig. 4, the valley bottom determining circuit may include a counter, a data register, a comparator, an AND circuit AND OR an OR circuit OR. The counter is cleared and counts the bottom number in each switching period at the beginning of each switching period, and the data register updates and holds the value obtained by subtracting one from the bottom number in the previous period at the beginning of each switching period. The comparator is used for comparing the values in the current counter AND the data register, the AND gate AND is used for realizing the logical AND operation of the comparator AND the OSC1 to obtain a first operation result, OR the OR gate OR is used for realizing the logical OR operation of the OSC2 AND the first operation result output by the AND gate AND to obtain a second operation result, AND the enable signal can be generated according to the second operation result.
Optionally, the value in the data register is updated before the counter is cleared.
In a specific implementation, the value in the data register should be updated before the counter is cleared.
In the specific implementation, assuming that the number of the operating valleys of the switching power supply in the previous period is N, the value in the data register is updated to N-1 and stored when the current period starts, and then the value in the counter is cleared. When the PWM circuit samples that the voltage of the third pin CS reaches the feedback voltage corresponding to the fourth pin FB, the PWM circuit immediately outputs a low level pulse, the valley bottom detection circuit starts to detect the valley bottom, when the second frequency signal OSC2 is high, OR the number m of the valley bottoms counted by the counter is greater than OR equal to N-1 (i.e., the comparator outputs high) and the first frequency signal OSC1 is high, the output enable signal EN of the OR gate circuit OR is high, i.e., the enable signal EN output by the valley bottom determination circuit is high, the PWM circuit will immediately output a high level pulse when the next valley bottom signal comes, at this time, the next switching period starts, the value in the data register is updated, the value in the counter is cleared, and the circuit thus performs a switching cycle.
Further, as shown in fig. 5, fig. 5 shows specific waveforms of various parts of the controller during operation in the embodiment of the present application, wherein the frequency of the clamp frequency signal OSC1 is higher than the frequency of OSC 2.
Assuming that the switching power supply in the previous period works at the Nth valley, the value in the data register in the initial period of the period is t 0 Is updated to N-1. The value of the counter is at t 1 The time is cleared to 0. At t 2 At that time, when the voltage of the third pin CS reaches the feedback voltage corresponding to the fourth pin FB, the second pin VG signal becomes a low level, the valley bottom detection circuit can detect a valley bottom signal, and the counter counts the number of valleys in the current period according to the valley bottom signal, where a waveform diagram before the count to the N-1 th valley bottom is omitted in fig. 5.
Further, the first clock signal OSC1 and the second clock signal OSC2 dynamically change according to the load feedback information, i.e., the voltage level of the fourth pin FB, for the case that the load power decreases and the valley number increases: the arrival time of the high level of the first clock signal OSC1 is at the bottom of the Nth valley t 4 After time, OSC1 is at t, as in FIG. 5 5 At time goes high, OSC2 at t 6 The time is changed to high level, and the valley bottom judging circuit is at t 5 Output high level at time t 7 The PWM circuit will output high level pulse when the time, namely the next valley bottom arrives, the counter is at t 8 The current working valley bottom number is recorded to be N +1 at the moment, and the value in the data register is at t 9 The time is updated to N, and then the value in the counter is at t 10 The time is reset, and the increment of the valley number in the working process of the period is realized; for the case that the load power increases and the number of the valleys decreases, the high level of the second clock signal OSC2 arrives at the bottom of the N-1 th valley t 3 Before the moment, the valley bottom judging circuit outputs the high level after the high level of the OSC2 arrives, and the PWM circuit outputs the high level immediately when the next valley bottom arrives, so that the reduction of the valley bottom number in the working process of the period is realized. Since the increase and decrease of the valley bottom number need to satisfy the above-mentioned conditions, in the embodiment of the present application, the circuit can lock the valley bottom number when the load is stable, and the switching of the valley bottom number of the switching power supply can occur only when the output power significantly changes, which causes the magnitude of the FB voltage of the fourth pin to significantly change, and the clamp frequency signals OSC1 and OSC2 also significantly change to reach the condition of increasing or decreasing the valley bottom number.
In specific implementation, in the embodiment of the present application, the valley bottom determining circuit may implement valley bottom locking according to a relationship between the two clamp frequency signals OSC1 and OSC2 and the number of valleys in the current period and the previous period, and at the same time, limit the maximum operating frequency of the switching power supply, improve the operating efficiency of the converter, and reduce audible noise during operation.
It can be seen that the switching power supply described in the embodiments of the present application, wherein the switching power supply includes: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the valley bottom detection circuit is connected with the valley bottom judgment circuit, the PWM circuit and a first pin of the control circuit, the valley bottom judgment circuit is connected with the OSC circuit and the PWM circuit, the PWM circuit is connected with a second pin, a third pin and a fourth pin of the control circuit, and the OSC circuit is connected with a fourth pin of the control circuit; the transformer comprises an auxiliary winding, a primary winding and a secondary winding, wherein one end of the auxiliary winding is connected with the first pin, and the other end of the auxiliary winding is grounded; one end of the primary winding is connected with an external power supply, and the other end of the primary winding is connected with the first end of the first switching tube; one end of the secondary winding is connected with the anode of the first diode, and the other end of the secondary winding is grounded; the cathode of the first diode is connected with a load; the PWM circuit is connected with the second end of the first switching tube through a second pin, and the PWM circuit is connected with the third end of the first switching tube, one end of the sampling resistor and the other end of the sampling resistor through a third pin and is grounded; the feedback circuit realizes the isolation of the primary and secondary stages through the optical coupler, and one end of the primary optical coupler is connected with the fourth pin of the control circuit and the other end of the primary optical coupler is grounded.
Further, the enable signal EN is generated by the valley bottom determination circuit and transmitted to the PWM circuit. The valley bottom judging circuit can combine two clamping frequency signals OSC1 and OSC2 with the valley bottom number of the switching power supply in the working process to output an enable EN signal, the enable EN signal is used for enabling the PWM circuit, so that the PWM circuit can output high-level pulses when the valley bottom arrives, the enable EN signal limits the maximum working frequency of the switching power supply, namely the maximum working frequency is limited below OSC1 or OSC2, meanwhile, the valley jump problem of the switching power supply is solved through the valley bottom judging circuit, and the working stability of the switching power supply is ensured.
In a specific implementation, the correspondence between the first and second clock signals OSC1 and OSC2 and the voltage of the fourth pin may be set in the OSC circuit in advance, and the switching sensitivity of the switching power supply may be adjusted by setting the difference between the OSC1 and the OSC 2.
This application embodiment promptly, can realize switching power supply's valley bottom number locking, restricted switching power supply's maximum operating frequency simultaneously, promoted switching power supply's job stabilization nature.
In the embodiment of the application, a charger can be further provided, and the charger comprises the switching power supply, so that the valley bottom locking of the switching power supply is realized, the maximum working frequency of the switching power supply is limited, and the stability of the charger is ensured.
The foregoing is an implementation of the embodiments of the present application, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the principle of the embodiments of the present application, and these modifications and decorations are also regarded as the protection scope of the present application.
Claims (8)
1. A switching power supply, characterized in that the switching power supply comprises: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the detection circuit comprises a valley bottom detection circuit, a valley bottom judgment circuit, an OSC circuit and a PWM circuit, wherein the valley bottom detection circuit is connected with the valley bottom judgment circuit, the PWM circuit and a first pin of the control circuit, the valley bottom judgment circuit is connected with the OSC circuit and the PWM circuit, the PWM circuit is connected with a second pin, a third pin and a fourth pin of the control circuit, and the OSC circuit is connected with a fourth pin of the control circuit;
the transformer comprises an auxiliary winding, a primary winding and a secondary winding, wherein one end of the auxiliary winding is connected with the first pin, and the other end of the auxiliary winding is grounded; one end of the primary winding is connected with an external power supply, and the other end of the primary winding is connected with the first end of the first switching tube; one end of the secondary winding is connected with the anode of the first diode, and the other end of the secondary winding is grounded; the cathode of the first diode is connected with a load;
the PWM circuit is connected with the second end of the first switch tube through the second pin, and the PWM circuit is connected with the third end of the first switch tube, one end of the sampling resistor and the other end of the sampling resistor through the third pin and is grounded;
the feedback circuit realizes the isolation of a primary side and a secondary side through a primary optocoupler, one end of the primary optocoupler is connected with a fourth pin of the control circuit, and the other end of the primary optocoupler is grounded; the first pin is connected with the output end of the auxiliary winding; the second pin is connected with the grid electrode of the first switching tube; the third pin is connected with the source electrode of the first switch tube; the fourth pin is used for detecting the voltage of a primary optocoupler of the feedback circuit;
the valley bottom detection circuit is used for detecting valley bottoms in the working process of the switching power supply, generating valley bottom signals and transmitting the valley bottom signals to the valley bottom judgment circuit and the PWM circuit;
the OSC circuit is used for generating a first frequency signal and a second frequency signal according to the voltage of a fourth pin after the switching tube is switched on every time, and transmitting the first frequency signal and the second frequency signal to the valley bottom judging circuit;
the valley bottom judging circuit is used for generating an enable signal according to the first frequency signal, the second frequency signal and the valley bottom signal, and specifically, when the number of the valley bottoms in the current period is greater than or equal to a value obtained by subtracting one from the number of the valley bottoms in the previous period and the first frequency signal is high, the enable signal generated by the valley bottom judging circuit is at a high level; when the second frequency signal is high, the enabling signal generated by the valley bottom judging circuit is high level, and the enabling signal is transmitted to the PWM circuit;
the PWM circuit is used for generating PWM pulses for driving a switch tube according to the enable signal, the valley bottom signal, the voltage of the third pin and the voltage of the fourth pin, and the PWM pulses are used for controlling the first switch tube to generate output voltage.
2. The switching power supply according to claim 1,
and the PWM circuit is used for outputting a high-level pulse immediately when the valley bottom signal arrives when the enable signal is high.
3. The switching power supply according to claim 1,
and the PWM circuit is used for immediately outputting low-level pulse when the voltage sampled to the third pin reaches the feedback voltage corresponding to the fourth pin.
4. The switching power supply according to claim 1, wherein the valley determination circuit comprises: the circuit comprises a counter, a data register, a comparator, an AND gate circuit and an OR gate circuit;
the counter is used for clearing and counting the valley bottom number in each switching period when each switching period is started;
the data register is used for updating and keeping a value obtained by subtracting one from the valley bottom number of the previous period into the data register at the beginning of each switching period;
the comparator is used for comparing the first value in the counter with the second value in the data register to obtain a comparison result;
the AND gate circuit is used for carrying out logical AND operation according to the comparison result and the first frequency signal to obtain a first operation result;
and the OR gate circuit is used for carrying out logical OR operation according to the second frequency signal and the first operation result to obtain a second operation result, and generating the enable signal according to the second operation result.
5. The switching power supply according to claim 4, wherein the value in the data register is updated before the counter is cleared.
6. The switching power supply according to any one of claims 1-5, wherein said first switching tube comprises an NMOS tube and a parasitic diode, or wherein said first switching tube comprises an NMOS tube.
7. The switching power supply according to any one of claims 1 to 5, wherein said external power supply is grounded through a first capacitor, and said first diode is grounded through a second capacitor.
8. A charger, characterized in that it comprises a switching power supply according to any one of claims 1-7.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210549633.2A CN114649958B (en) | 2022-05-20 | 2022-05-20 | Switching power supply and charger |
| CN202211051012.8A CN117134617A (en) | 2022-05-20 | 2022-05-20 | Switching power supply and related charger |
| PCT/CN2023/092944 WO2023221812A1 (en) | 2022-05-20 | 2023-05-09 | Switch power source and charger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210549633.2A CN114649958B (en) | 2022-05-20 | 2022-05-20 | Switching power supply and charger |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211051012.8A Division CN117134617A (en) | 2022-05-20 | 2022-05-20 | Switching power supply and related charger |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114649958A CN114649958A (en) | 2022-06-21 |
| CN114649958B true CN114649958B (en) | 2022-07-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210549633.2A Active CN114649958B (en) | 2022-05-20 | 2022-05-20 | Switching power supply and charger |
| CN202211051012.8A Pending CN117134617A (en) | 2022-05-20 | 2022-05-20 | Switching power supply and related charger |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211051012.8A Pending CN117134617A (en) | 2022-05-20 | 2022-05-20 | Switching power supply and related charger |
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| Country | Link |
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| CN (2) | CN114649958B (en) |
| WO (1) | WO2023221812A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114649958B (en) * | 2022-05-20 | 2022-07-29 | 深圳英集芯科技股份有限公司 | Switching power supply and charger |
Citations (4)
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| CN102208871A (en) * | 2010-06-11 | 2011-10-05 | 崇贸科技股份有限公司 | Switching power converter and switching control circuit thereof |
| CN108173435A (en) * | 2018-02-08 | 2018-06-15 | 无锡硅动力微电子股份有限公司 | Switching Power Supply control unit and the adaptive the lowest point lock-in circuit of Quasi-resonant switching power supply |
| CN108599320A (en) * | 2018-06-04 | 2018-09-28 | 深圳英集芯科技有限公司 | A kind of wireless charging system |
| CN109067213A (en) * | 2018-08-08 | 2018-12-21 | 苏州博创集成电路设计有限公司 | The switch power controller and control method of quasi-resonant mode |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9431911B2 (en) * | 2014-07-16 | 2016-08-30 | Grenergy Opto Inc. | Switching mode power supply capable of providing a block time in response to an output current |
| US9929657B2 (en) * | 2015-02-17 | 2018-03-27 | Semiconductor Components Industries, Llc | Alternating valley switching for power converter |
| CN109302066B (en) * | 2017-07-25 | 2020-06-26 | 上海三思电子工程有限公司 | Sampling circuit of primary inductance peak current in switching power supply and switching power supply |
| CN111490681B (en) * | 2020-05-07 | 2024-07-02 | 东科半导体(安徽)股份有限公司 | Quasi-resonant switching power supply controller based on valley locking |
| CN213585566U (en) * | 2020-11-11 | 2021-06-29 | 富满微电子集团股份有限公司 | Valley bottom locking circuit based on quasi-resonance control technology, chip and power supply |
| CN114649958B (en) * | 2022-05-20 | 2022-07-29 | 深圳英集芯科技股份有限公司 | Switching power supply and charger |
-
2022
- 2022-05-20 CN CN202210549633.2A patent/CN114649958B/en active Active
- 2022-05-20 CN CN202211051012.8A patent/CN117134617A/en active Pending
-
2023
- 2023-05-09 WO PCT/CN2023/092944 patent/WO2023221812A1/en unknown
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102208871A (en) * | 2010-06-11 | 2011-10-05 | 崇贸科技股份有限公司 | Switching power converter and switching control circuit thereof |
| CN108173435A (en) * | 2018-02-08 | 2018-06-15 | 无锡硅动力微电子股份有限公司 | Switching Power Supply control unit and the adaptive the lowest point lock-in circuit of Quasi-resonant switching power supply |
| CN108599320A (en) * | 2018-06-04 | 2018-09-28 | 深圳英集芯科技有限公司 | A kind of wireless charging system |
| CN109067213A (en) * | 2018-08-08 | 2018-12-21 | 苏州博创集成电路设计有限公司 | The switch power controller and control method of quasi-resonant mode |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114649958A (en) | 2022-06-21 |
| CN117134617A (en) | 2023-11-28 |
| WO2023221812A1 (en) | 2023-11-23 |
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