CN117134617A - Switching power supply and related charger - Google Patents
Switching power supply and related charger Download PDFInfo
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- CN117134617A CN117134617A CN202211051012.8A CN202211051012A CN117134617A CN 117134617 A CN117134617 A CN 117134617A CN 202211051012 A CN202211051012 A CN 202211051012A CN 117134617 A CN117134617 A CN 117134617A
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- 238000001514 detection method Methods 0.000 claims abstract description 20
- 238000005070 sampling Methods 0.000 claims abstract description 11
- 239000003990 capacitor Substances 0.000 claims description 8
- 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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Classifications
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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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The embodiment of the application discloses a switching power supply and a related charger, wherein the switching power supply comprises: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the device 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 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, wherein the auxiliary winding is connected with the valley 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 with a load; the PWM circuit is connected with the first switch tube, one end of the sampling resistor and the other end of the sampling resistor to the ground, and the PWM circuit is connected with the primary optocoupler in the feedback circuit and the other end of the primary optocoupler to the ground. The embodiment of the application can realize the valley number locking of the switching power supply.
Description
Technical Field
The application relates to the technical field of electronics, in particular to a switching power supply and a related charger.
Background
Currently, an electronic device (such as a mobile phone) can use a USB charger to charge the electronic device, and a switching power supply is an important component of the charger, and in practice, the operating frequency range of the switching power supply is limited by using a maximum frequency clamp. However, when the operating frequency of the switching power supply is near the maximum clamping frequency, the switching power supply typically hops between two or even more valleys, which can 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 related charger, which not only limit the maximum working frequency of the switching power supply, but also realize the valley number locking of the switching power supply, thereby improving the working stability of the switching power supply.
In a first aspect, an embodiment of the present application provides the switching power supply, including: control circuit, transformer, first switching tube, first diode, feedback circuit, control circuit includes: the device comprises a valley bottom detection circuit, a valley bottom judging circuit, an OSC circuit and a PWM circuit, wherein the valley bottom detection circuit is connected with the valley bottom judging circuit, the PWM circuit and a first pin of a control circuit, the valley bottom judging 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 the 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 the second pin, and is connected with the third end of the first switching tube and one end of the sampling resistor through the third pin, and the other end of the sampling resistor is grounded;
the feedback circuit realizes primary and secondary isolation through an optocoupler, and 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.
In a second aspect, embodiments of the present application provide a charger comprising 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 device comprises a valley bottom detection circuit, a valley bottom judging circuit, an OSC circuit and a PWM circuit, wherein the valley bottom detection circuit is connected with first pins of the valley bottom judging circuit, the PWM circuit and the control circuit, the valley bottom judging circuit is connected with the OSC circuit and the PWM circuit, and the PWM circuit is connected with second pins and third pins 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 a 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 the second pin, and is connected with the third end of the first switching tube through the third pin and grounded through the sampling resistor.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a switching power supply according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of another switching power supply according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a switching tube according to an embodiment of the present application;
fig. 4 is a schematic structural diagram of a valley bottom judging circuit according to an embodiment of the present application;
fig. 5 is a schematic diagram of waveforms during operation according to an embodiment of the present application.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The terms first, second and the like in the description and in the claims and in the above-described figures are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may 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 may be included in at least one embodiment of the application. The appearances of such phrases 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. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
Embodiments of the present application are described in detail below.
In the related art, an operating frequency of a switching power supply operating in a resonant mode (QR) is inversely proportional to a load, please refer to fig. 1, fig. 1 is a switching power supply in the related art, which includes a control circuit including a valley detection circuit, an Oscillator (OSC), and a pulse width modulation circuit (pulse width modulation, PWM). The valley detection circuit can be used for realizing valley 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 FB pin voltage, and the PWM circuit is used for generating PWM pulses for driving the switching tube.
Among them, the oscillator may also be called an OSC circuit, and the pulse width modulation circuit may also be called a PWM circuit.
In a specific implementation, when the operating frequency is near the maximum clamping frequency, the switching power supply typically hops between two or more valleys, which can cause the operating frequency of the switching power supply to fluctuate dramatically, affecting loop stability and producing audible noise.
In order to solve the above-mentioned drawbacks, 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, as shown in the drawings, in which the switching power supply includes: control circuit, transformer and first switch tube Q 1 First diode D 1 A feedback circuit, the control circuit comprising: a valley detection circuit, a valley judgment circuit, an OSC circuit and a PWM circuit, wherein the valley detection circuit is connected with the valley judgment circuit, the PWM circuit and a first pin VS of the control circuit, the valley 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 is connected with the first switch tube Q 1 Is a first end of (2); one end of the secondary winding is connected with the first diode D 1 The anode and the other end of the capacitor are grounded; the first diode D 1 Is connected to the load through the cathode of V out Connecting a load; the PWM circuit is connected with the first switch tube Q through the second pin VG 1 The PWM circuit is connected with the first switch tube Q through the third pin CS 1 And a sampling resistor R sense One end of (2) and sampling resistor R sense The other end of which is grounded.
The feedback circuit realizes primary and secondary isolation through an optocoupler, one end of the primary optocoupler Opto is connected with a fourth pin FB of the control circuit and the other end of the primary optocoupler Opto is grounded, the feedback circuit transmits a load feedback signal, namely a fourth pin FB voltage, into the OSC circuit and the PWM circuit through the primary optocoupler Opto, the OSC circuit generates a corresponding frequency signal according to the fourth pin FB voltage, and the PWM circuit obtains a feedback voltage corresponding to a third pin CS according to the fourth pin FB voltage.
Wherein the feedback circuit further comprises a secondary optocoupler Opto, one end of which passes through the first resistor R 1 Is connected with a first diode D 1 The other end of the secondary optocoupler Opto is grounded through the precision reference source TL431, and the feedback circuit is connected through the precision reference source TL431 and a third resistor R 3 And a fourth resistor R 4 Realize the voltage stabilizing function, the third resistor R 3 One end is connected with a fourth resistor R 4 And the other end is grounded, the fourth resistor R 4 The other end of (a) is connected with a first diode D 1 In addition, a second resistance R 2 Connected in parallel to two ends of the secondary optocoupler Opto, one end of the secondary optocoupler Opto passing through the compensation componentAnd through a third resistor R 3 The compensation assembly comprises a resistor R connected in series comp And a capacitor C comp . The feedback circuit realizes the primary and secondary feedback functions through an optocoupler.
Wherein the first pin VG is used for driving the first switching tube Q 1 The second pin VS is used for detecting the voltage variation 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 fourth pin FB voltage, the faster the frequency.
In the specific implementation, the homonymous end of the auxiliary winding is connected with a first pin VS, and the heteronymous end of the auxiliary winding is grounded; the homonymous 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 homonymous end of the secondary winding is connected with the anode of the first diode, and the heteronymous end of the secondary winding is grounded.
Optionally, the first switching tube comprises an NMOS tube and a parasitic diode, or the first switching tube comprises an NMOS tube.
In particular, as shown in FIG. 3, a first switching tube Q 1 May include NMOS transistor and parasitic diode, the 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 is the drain, the second terminal is the gate, and the third terminal is the source. The positive stage of the parasitic diode is connected with the first switch tube Q 1 A cathode of the parasitic diode is connected with the first switch tube Q 1 Is provided.
Of course, the first switching tube Q 1 The device can also be composed of only one NMOS tube, wherein the first end of the NMOS tube is a drain electrode, the second end of the NMOS tube is a grid electrode and the third end of the NMOS tube 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 a first capacitor C in Grounded (earth)First diode D 1 Through a second capacitor C o And (5) grounding.
Optionally, the valley detection circuit is configured to detect a valley in the working process of the switching power supply, generate a valley signal, and transmit the valley signal to the valley judgment circuit and the PWM circuit;
the OSC circuit is configured to generate a first frequency signal and a second frequency signal according to a voltage of the fourth pin FB after each switching tube is turned on, and transmit 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 enabling signal according to the first frequency signal, the second frequency signal and the valley bottom signal and transmitting the enabling signal to the PWM circuit;
the PWM circuit is used for generating PWM pulses for driving the switching tube according to the enabling signal, the valley signal, the third pin CS voltage and the fourth pin FB voltage, and the PWM pulses are used for controlling the first power tube to generate output voltage.
In a specific implementation, the Valley detection circuit can be used for detecting the Valley in the working process of the switching power supply and generating a Valley signal Valley, and then transmitting the generated Valley signal to the PWM circuit and the Valley judgment circuit.
In addition, the OSC circuit may be configured to generate two clamp frequency signals according to the FB voltage of the fourth pin after each switch is turned on: the first frequency signal OSC1 and the second frequency signal OSC2, and then the clamp frequency signals OSC1 and OSC2 are transmitted to the valley bottom judging circuit; the two clamp frequency signals OSC1 and OSC2 may then be used to limit the maximum operating frequency of the switching power supply according to the load feedback information, i.e., the fourth pin FB voltage.
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 the two clamping frequency signals OSC1 and OSC2 with the valley bottom number in the working process of the switching power supply to output an enable EN signal, wherein 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 to generate PWM pulse for driving the switching tube, and the PWM pulse is used to control 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 arrives.
Optionally, the PWM circuit is configured to output a high-level pulse immediately when the valley signal arrives when the enable signal is high;
in a specific implementation, 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 arrives.
Optionally, the PWM circuit is configured to output a low-level pulse immediately when the voltage sampled to the third pin reaches the feedback voltage corresponding to the fourth pin.
In a specific implementation, when the voltage sampled by the PWM circuit to the third pin CS reaches the feedback voltage corresponding to the fourth pin FB, the PWM circuit will immediately output a low-level pulse.
Optionally, the valley bottom judging circuit includes: the device comprises a counter, a data register, a comparator, an AND gate circuit and an OR gate circuit;
the counter is used for resetting and counting the valley bottom number in each switching period when each switching period is initialized;
the data register is used for updating the value of subtracting one from the valley bottom number of the previous period into the data register and keeping the value when each switching period is started;
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 enabling 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 gate AND an OR gate OR. The counter clears and counts the valley bottom number in each switching period at the beginning of each switching period, and the data register updates and maintains the value of the valley bottom number of the last period minus one into the data register at the beginning of each switching period. The comparator is used for comparing the current counter with the median value of 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, 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, updating the value in the data register is cleared prior to the counter.
In particular implementations, the value in the data register should be updated prior to the counter being cleared.
In a specific implementation, assuming that the bottom of the working valley of the switching power supply in the previous period is N, the value in the data register is updated to N-1 and stored at the beginning of the current period, 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 detection circuit starts to detect the valley, when the second frequency signal OSC2 is high, OR when the number m of the valleys counted by the counter is greater than OR equal to N-1 (i.e. the output of the comparator is high) and the first frequency signal OSC1 is high, the output enable signal EN of the OR circuit is high, i.e. the enable signal EN output by the valley judgment circuit is high, the PWM circuit immediately outputs a high level pulse when the next valley signal arrives, at this time, the next switching cycle starts, the value in the data register is updated, the value in the counter is cleared, and the circuit performs switching cycle in this way.
Further, as shown in fig. 5, fig. 5 shows a specific waveform of each part in the operation process of the controller in the embodiment of the present application, where the frequency of the clamp frequency signal OSC1 is higher than the frequency of OSC 2.
Assuming that the switching power supply of the previous cycle is operated at the Nth valley, the value in the data register at the initial stage of the cycle 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 When the voltage of the third pin CS reaches the feedback voltage corresponding to the fourth pin FB, the signal of the second pin VG becomes low level, the valley bottom detection circuit may detect the valley bottom signal, and the counter counts the valley bottom number of the current period according to the valley bottom signal, where the waveform diagram before counting to the N-1 th valley bottom is omitted in fig. 5.
Further, the first frequency signal OSC1 and the second frequency signal OSC2 dynamically change according to the load feedback information, i.e. the voltage of the fourth pin FB, and the valley count increases when the load power decreases: the arrival time of the high level of the first frequency signal OSC1 is at the Nth valley, i.e. t in the diagram 4 After the time, as in FIG. 5, OSC1 is at t 5 Time goes high, OSC2 at t 6 The time becomes high level, and the valley bottom judging circuit will at t 5 Output high level at time, so at t 7 The PWM circuit outputs high level pulse when the moment, the next valley arrives, and the counter is at t 8 The current valley bottom number recorded at the moment is N+1, and the value in the data register is t 9 The time is updated to N, then the value in the counter is at t 10 The moment is cleared, and the increase of the valley bottom number in the working process of the period is realized at the moment; for the situation that the load power increases and the valley bottom decreases, the time when the high level of the second frequency signal OSC2 arrives is at the N-1 valley bottom, i.e. t in the figure 3 Before the moment, the valley bottom judging circuit can output high level after the OSC2 high level arrives at this moment, and the PWM circuit can output high level immediately when the next valley bottom arrives at this moment, so that the reduction of the valley bottom number in the period working process is realized. Because the increase and decrease of the valley count are required to satisfy the above conditions, the circuit can lock the valley count when the load is stable in the embodiment of the application, and cause the fourth pin FB voltage only when the output power is significantly changedThe magnitude of the clamp frequency signals OSC1 and OSC2 also changes significantly, and the switching power supply will switch the valley number when the condition that the valley number is increased or decreased is achieved.
In a specific implementation, in the embodiment of the application, the valley bottom judging circuit can realize valley bottom locking according to the relation between the two clamping frequency signals OSC1 and OSC2 and the valley bottom of the current period and the valley bottom of the previous period, and meanwhile, the maximum working frequency of the switching power supply is limited, the working efficiency of the converter is improved, and the audible noise during working is reduced.
It can be seen that the switching power supply described in the embodiment of the present application, wherein the switching power supply includes: control circuit, transformer, first switch tube, first diode, feedback circuit, control circuit includes: the device comprises a valley bottom detection circuit, a valley bottom judging circuit, an OSC circuit and a PWM circuit, wherein the valley bottom detection circuit is connected with first pins of the valley bottom judging circuit, the PWM circuit and the control circuit, the valley bottom judging circuit is connected with the OSC circuit and the PWM circuit, the PWM circuit is connected with second pins, third pins and fourth pins of the control circuit, and the OSC circuit is connected with the fourth pins 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 a 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 the second pin, and is connected with the third end of the first switching tube and one end of the sampling resistor through the third pin, and the other end of the sampling resistor is grounded; the feedback circuit realizes primary and secondary isolation through an optical coupler, and one end of the primary optical coupler is connected with a fourth pin of the control circuit and the other end of the primary optical coupler is grounded.
Further, an enable signal EN is generated by the valley bottom determination circuit, and the enable signal EN is transferred to the PWM circuit. The valley bottom judging circuit can combine the two clamping frequency signals OSC1 and OSC2 with the valley bottom number in the working process of the switching power supply 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, 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 bottom judging circuit solves the problem of valley jumping of the switching power supply, and the working stability of the switching power supply is ensured.
In a specific implementation, the correspondence between the first frequency signal OSC1 and the second frequency signal OSC2 and the fourth pin voltage may be set in the OSC circuit in advance, and meanwhile, the switching sensitivity of the switching power supply may be adjusted by setting the magnitude of the difference between OSC1 and OSC 2.
The embodiment of the application can realize the valley number locking of the switching power supply, limit the maximum working frequency of the switching power supply and improve the working stability of the switching power supply.
In the embodiment of the application, the charger also comprises the switch power supply, the switch power supply realizes valley locking, the maximum working frequency of the switch power supply is limited, and the stability of the charger is ensured.
The foregoing is a description of embodiments of the present application, and it should be noted that, for those skilled in the art, modifications and variations can be made without departing from the principles of the embodiments of the present application, and such modifications and variations are also considered to be within the scope of the present application.
Claims (9)
1. A switching power supply is characterized in that,
the switching power supply includes: the control circuit, the transformer, the first switching tube, the first diode and the feedback circuit;
wherein the control circuit includes: a valley bottom detection circuit, a valley bottom judgment circuit, an OSC circuit, and a PWM circuit;
wherein,
the valley detection circuit is connected with the valley judging circuit, the PWM circuit and the first pin of the control circuit, the valley judging circuit is connected with the OSC circuit and the PWM circuit, the PWM circuit is connected with the second pin, the third pin and the fourth pin of the control circuit, and the OSC circuit is connected with the 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 the second pin, and is connected with the third end of the first switching tube and one end of the sampling resistor through the third pin, and the other end of the sampling resistor is grounded;
the feedback circuit realizes primary and secondary isolation through a primary optocoupler, and 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.
2. The switching power supply of claim 1 wherein said valley detection circuit is configured to detect a valley during operation of said switching power supply and to generate a valley signal and to communicate said valley signal to said valley determination circuit and said PWM circuit;
the OSC circuit is configured to generate a first frequency signal and a second frequency signal according to a voltage of a fourth pin after each switching tube is turned on, and transmit 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 enabling signal according to the first frequency signal, the second frequency signal and the valley bottom signal and transmitting the enabling signal to the PWM circuit;
the PWM circuit is used for generating PWM pulses for driving the switching tube according to the enabling signals, the valley signals, the third pin and the fourth pin voltage, and the PWM pulses are used for controlling the first switching tube to generate output voltages.
3. A switching power supply as defined in claim 2, wherein,
the PWM circuit is used for outputting high-level pulse immediately when the valley signal arrives when the enable signal is high.
4. A switching power supply as defined in claim 2, wherein,
and the PWM circuit is used for outputting low-level pulses immediately when the voltage sampled to the third pin reaches the feedback voltage corresponding to the fourth pin.
5. The switching power supply according to any one of claims 2 to 4, wherein the valley bottom judgment circuit includes: the device comprises a counter, a data register, a comparator, an AND gate circuit and an OR gate circuit;
the counter is used for resetting and counting the valley bottom number in each switching period when each switching period is initialized;
the data register is used for updating the value of subtracting one from the valley bottom number of the previous period into the data register and keeping the value when each switching period is started;
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 enabling signal according to the second operation result.
6. The switching power supply of claim 5 wherein the update of the value in the data register is cleared prior to the counter.
7. The switching power supply according to any one of claims 1 to 6, wherein the first switching transistor comprises an NMOS transistor and a parasitic diode, or wherein the first switching transistor comprises an NMOS transistor.
8. The switching power supply of any one of claims 1-7 wherein the external power supply is grounded via a first capacitor and the first diode is grounded via a second capacitor.
9. A charger comprising a switching power supply as claimed in any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211051012.8A CN117134617A (en) | 2022-05-20 | 2022-05-20 | Switching power supply and related charger |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211051012.8A CN117134617A (en) | 2022-05-20 | 2022-05-20 | Switching power supply and related charger |
| CN202210549633.2A CN114649958B (en) | 2022-05-20 | 2022-05-20 | Switching power supply and charger |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CN202210549633.2A Division CN114649958B (en) | 2022-05-20 | 2022-05-20 | Switching power supply and charger |
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| Publication Number | Publication Date |
|---|---|
| CN117134617A true CN117134617A (en) | 2023-11-28 |
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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 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202210549633.2A Active CN114649958B (en) | 2022-05-20 | 2022-05-20 | Switching power supply and charger |
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| CN (2) | CN114649958B (en) |
| WO (1) | WO2023221812A1 (en) |
Families Citing this family (1)
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| 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 |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8482937B2 (en) * | 2010-06-11 | 2013-07-09 | System General Corporation | Switching control circuits with valley lock for power converters |
| 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 |
| CN108173435B (en) * | 2018-02-08 | 2023-08-15 | 无锡硅动力微电子股份有限公司 | Switch power supply control unit and quasi-resonant switch power supply self-adaptive valley locking circuit |
| 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 |
| CN109067213B (en) * | 2018-08-08 | 2019-12-20 | 苏州博创集成电路设计有限公司 | Switching power supply controller in quasi-resonance mode and control method |
| CN111490681A (en) * | 2020-05-07 | 2020-08-04 | 安徽省东科半导体有限公司 | Quasi-resonance switch power supply controller based on valley bottom 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
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2023
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| Publication number | Publication date |
|---|---|
| WO2023221812A1 (en) | 2023-11-23 |
| CN114649958B (en) | 2022-07-29 |
| CN114649958A (en) | 2022-06-21 |
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