CN213027823U - Switching power supply circuit - Google Patents
Switching power supply circuit Download PDFInfo
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- CN213027823U CN213027823U CN202021529658.9U CN202021529658U CN213027823U CN 213027823 U CN213027823 U CN 213027823U CN 202021529658 U CN202021529658 U CN 202021529658U CN 213027823 U CN213027823 U CN 213027823U
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Abstract
The utility model discloses a switching power supply circuit, which comprises a chip power supply circuit, a voltage detection circuit, a first charging circuit and a second charging circuit; the chip power supply circuit is used for controlling the connection and disconnection of the power supply input end and the power supply end of the chip; the voltage detection circuit is used for detecting the actual measurement voltage of the power supply end of the chip; the first charging circuit is used for forming a first power supply signal in a first charging stage of each charging period of the switching power supply chip and controlling the power supply circuit of the chip to be switched on and off according to the first power supply signal; the second charging circuit is used for forming a second power supply signal in a second charging stage of each charging period of the switching power supply chip and controlling the power supply circuit of the chip to be switched on and switched off according to the second power supply signal. According to the technical scheme, the switching power supply circuit can guarantee normal work of the switching power supply chip in the charging period of the switching power supply chip under the condition that no auxiliary winding exists.
Description
Technical Field
The utility model relates to a switching power supply field especially relates to a switching power supply circuit.
Background
The switching power supply is widely applied to the industries of electric power, communication, fire fighting and the like at present. The switching power supply converts commercial power into constant output voltage and output current through a transformer. Due to the large amplitude variation between the peaks and the troughs of the mains supply, when the switching power supply is applied in countries with high mains supply peaks, such as india, higher requirements are put on the reliability of the switching power supply during operation.
In the prior art, as shown in fig. 1, a switching power supply circuit is provided. The switching power supply circuit comprises a constant-current constant-voltage circuit 100, a rectifying and filtering circuit 200 and a switching power supply chip IC.
In the working process of the switching power supply, when the switching tube integrated in the switching power supply chip IC is in a conducting state, the rectification filter circuit 200 charges the primary winding LP, and under the action of the auxiliary winding LA, the feedback pin VFB of the switching power supply chip IC obtains a feedback negative voltage, which is the refraction of the line voltage of the switching power supply circuit. When the switching tube is turned off, the energy in the primary winding LP is transferred to the secondary winding LS, the cathode of the diode D6 and the secondary winding LS obtain the output voltage Vout, and the output voltage Vout is fed back to the feedback pin VFB of the switching power chip IC under the action of the auxiliary winding LA, so that the detection of the output voltage Vout can only occur within the degaussing time TDS of the switching power chip IC of the diode D6. The switching power supply chip IC calculates and obtains the conduction time and the working frequency of the power switching tube Q according to the feedback output voltage Vout to realize the constant current and constant voltage functions.
In the field of existing switching power supplies, an auxiliary winding LA in a switching power supply circuit is usually removed, a floating drive architecture is adopted, the floating drive architecture can achieve constant-voltage and constant-current control under the condition that the auxiliary winding LA is not provided, as shown in fig. 1, a switching power supply chip IC detects a relative voltage difference of partial voltage between R3 and R4 through a VFB pin, the output voltage of the switching power supply circuit without the auxiliary winding LA can be reflected, and constant-voltage and constant-current control can be achieved based on the output voltage detected by the VFB pin. However, the switching power supply circuit with the auxiliary winding LA supplies power to the switching power supply chip IC through the auxiliary winding LA, and now, after the auxiliary winding LA is removed, the switching power supply chip IC cannot obtain an energy source, and if all the power is supplied to the switching power supply chip IC by the starting resistor R1, the power consumption of the switching power supply chip IC is very large.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a switching power supply circuit to the solution is under the condition of no auxiliary winding, and switching power supply circuit can't make switching power supply chip normally realize the problem of constant current constant voltage function.
The embodiment provides a switching power supply circuit, which comprises a switching power supply chip, a chip power supply circuit, a voltage detection circuit, a first charging circuit and a second charging circuit, wherein the chip power supply circuit is connected with the first charging circuit;
the chip power supply circuit is connected with a power supply input end and a chip power end of the switching power supply chip and is used for controlling the connection and disconnection of the power supply input end and the chip power end;
the voltage detection circuit is connected with the chip power supply circuit and is used for detecting the actually measured voltage of the power end of the chip;
the first charging circuit is connected with the voltage detection circuit and the chip power supply circuit and is used for forming a first power supply signal according to the actually measured voltage input by the voltage detection circuit in the first charging stage of each charging period of the switching power supply chip and controlling the chip power supply circuit to be switched on and switched off according to the first power supply signal;
and the second charging circuit is connected with the voltage detection circuit and the chip power supply circuit and is used for forming a second power supply signal according to the actually measured voltage input by the voltage detection circuit in a second charging stage of each charging period of the switching power supply chip and controlling the chip power supply circuit to be switched on and switched off according to the second power supply signal.
Further, the chip power supply circuit comprises a chip power supply switch tube and a current limiting tube;
the chip power supply switch tube is connected with the power supply input end, the current limiting tube, the first charging circuit and the second charging circuit;
the current limiting tube is connected with the chip power supply switch tube and the chip power end.
Furthermore, the control end of the chip power supply switch tube is connected with the first charging circuit, the first connection end is connected with the power supply input end, and the second connection end is connected with the current limiting tube and the second charging circuit.
Furthermore, the current limiting tube is a current limiting diode, the anode of the current limiting tube is connected with the chip power supply switch tube, and the cathode of the current limiting tube is connected with the chip power supply end;
or the current-limiting tube is a triode, the collector of the current-limiting tube is connected with the chip power supply switch tube, the emitter of the current-limiting tube is connected with the power end of the chip, and the base of the current-limiting tube is connected with the collector of the current-limiting tube;
or the current-limiting tube is an MOS tube, the drain electrode of the current-limiting tube is connected with the chip power supply switch tube, the source electrode of the current-limiting tube is connected with the chip power supply end, and the grid electrode of the current-limiting tube is connected with the drain electrode of the current-limiting tube.
Further, the voltage detection circuit comprises a first voltage-dividing resistor, a second voltage-dividing resistor and a third voltage-dividing resistor which are arranged in series between a power supply end and a ground end of the chip.
Further, the first charging circuit comprises a first comparator, a first logic gate and a first control switch tube;
the first comparator is connected with the first voltage-dividing resistor and the second voltage-dividing resistor, and is configured to collect a first measured voltage between the first voltage-dividing resistor and the second voltage-dividing resistor in a first charging stage of each charging cycle of the switching power supply chip, and form a first power supply signal according to the first measured voltage and a first reference voltage;
the first logic gate is connected with the first comparator and used for forming a first charging signal according to the first power supply signal;
and the first control switch tube is connected with the first logic gate and the chip power supply switch tube and is used for controlling the chip power supply switch tube to be switched on or switched off according to the first charging signal.
Further, the first charging circuit further comprises a first reference circuit, and the first reference circuit is connected to the first comparator and is configured to provide a first reference voltage to the first comparator.
Further, the second charging circuit comprises a second comparator, a second logic gate and a second control switch tube;
the second comparator is connected with the second voltage-dividing resistor and the third voltage-dividing resistor, and is configured to collect a second measured voltage between the second voltage-dividing resistor and the third voltage-dividing resistor in a second charging stage of each charging cycle of the switching power supply chip, and form a second power supply signal according to the second measured voltage and a second reference voltage;
the second logic gate is connected with the second comparator and used for forming a second charging signal according to the second power supply signal;
and the second control switch tube is connected with the second logic gate and the chip power supply switch tube and is used for controlling the chip power supply switch tube to be switched on or switched off according to the second charging signal.
Further, the second charging circuit further comprises a second reference circuit, and the second reference circuit is connected to the second comparator and is configured to provide a second reference voltage to the second comparator.
Further, the second charging circuit further comprises a blanking time circuit connected to the second logic gate for providing a blanking period signal to the second logic gate; the second logic gate forms the second charging signal according to the second power supply signal and the blanking period signal.
In the switch power supply circuit, under the condition of no auxiliary winding, the chip power supply circuit 10 is adopted to control the conduction of a power supply input end Vin and a chip power end VDD to supply power to a switch power supply chip; the voltage detection circuit 20 is adopted to detect the actual measurement voltage of the power supply end VDD of the chip; the first charging circuit 30 forms a first power supply signal according to the actually measured voltage input by the voltage detection circuit 20 in the first charging stage of each charging cycle of the switching power supply chip, and controls the chip power supply circuit 10 to be switched on and off according to the first power supply signal; the second charging circuit 40 forms a second power supply signal according to the measured voltage input by the voltage detection circuit 20 in the second charging phase of each charging cycle of the switching power supply chip, and controls the chip power supply circuit 10 to be switched on and off according to the second power supply signal, so that the switching power supply circuit can ensure the normal work of the switching power supply chip in the charging cycle of the switching power supply chip without an auxiliary winding.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.
FIG. 1 is a circuit diagram of the prior art;
fig. 2 is a circuit diagram of a switching power supply circuit according to an embodiment of the present invention;
fig. 3 is another circuit diagram of the switching power supply circuit according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a waveform according to an embodiment of the present invention;
fig. 5 is another schematic waveform diagram in an embodiment of the invention;
fig. 6 is another schematic waveform diagram in an embodiment of the present invention.
10. A chip power supply circuit; 20. a voltage detection circuit; 30. a first charging circuit; 31. a first comparator; 32. a first logic gate; 40. a second charging circuit; 41. a second comparator; 42. a second logic gate; 43. a blanking time circuit.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity to indicate like elements throughout.
It will be understood that when an element or layer is referred to as being "on" …, "adjacent to …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …," "directly adjacent to …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatial relationship terms such as "under …", "under …", "below", "under …", "above …", "above", and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below …" and "below …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In order to provide a thorough understanding of the present invention, detailed structures and steps will be provided in the following description so as to explain the technical solution provided by the present invention. The preferred embodiments of the present invention are described in detail below, however, other embodiments of the present invention are possible in addition to these detailed descriptions.
The present embodiment provides a switching power supply circuit, as shown in fig. 2 and fig. 3, including a switching power supply chip, further including a chip power supply circuit 10, a voltage detection circuit 20, a first charging circuit 30, and a second charging circuit 40; the chip power supply circuit 10 is connected with the power supply input end Vin and a chip power end VDD of the switch power supply chip and is used for controlling the connection and disconnection of the power supply input end Vin and the chip power end VDD; the voltage detection circuit 20 is connected with the chip power supply circuit 10 and is used for detecting the actually measured voltage of the power supply end VDD of the chip; the first charging circuit 30 is connected with the voltage detection circuit 20 and the chip power supply circuit 10, and is used for forming a first power supply signal according to the actually measured voltage input by the voltage detection circuit 20 in the first charging stage of each charging cycle of the switching power supply chip, and controlling the chip power supply circuit 10 to be switched on and off according to the first power supply signal; and the second charging circuit 40 is connected with the voltage detection circuit 20 and the chip power supply circuit 10, and is configured to form a second power supply signal according to the actually measured voltage input by the voltage detection circuit 20 in a second charging stage of each charging cycle of the switching power supply chip, and control the chip power supply circuit 10 to be turned on and off according to the second power supply signal.
The power supply input terminal Vin is a power supply terminal for supplying power to the switching power supply chip. The chip power supply end VDD is a power supply end of the switch power supply chip. The actually measured voltage is a voltage obtained by the voltage detection circuit 20 detecting the chip power supply terminal VDD of the switching power supply chip in real time. The charging period is a period for supplying power to the switching power supply chip so as to keep the voltage of the switching power supply chip stable. Generally, each charging cycle includes a first charging phase and a second charging phase. The first charging stage is a stage of switching the power supply chip to perform first charging in a charging cycle. The second charging stage is a stage of performing second charging on the switching power supply chip in the charging period.
As an example, as shown in fig. 3, the chip power supply circuit 10 is connected to a power supply input terminal Vin and a chip power supply terminal VDD, when the switching power supply chip needs to supply power, the chip power supply circuit 10 is turned on, and the power supply input terminal Vin supplies power to the chip power supply terminal VDD through the chip power supply circuit 10; when the switching power supply chip does not need to supply power, the chip power supply circuit 10 is disconnected, and the power supply input terminal Vin stops supplying power to the chip power supply terminal VDD.
As an example, as shown in fig. 3, the voltage detection circuit 20 is connected to the chip power supply circuit 10, and when the power supply input terminal Vin supplies power to the chip power terminal VDD through the chip power supply circuit 10 or the power supply input terminal Vin stops supplying power to the chip power terminal VDD, the voltage detection circuit 20 detects the chip power terminal VDD in real time to obtain a measured voltage corresponding to the chip power terminal VDD.
As an example, as shown in fig. 3, the first charging circuit 30 is connected to the voltage detection circuit 20 and the chip power supply circuit 10, and the first charging circuit 30 obtains the measured voltage output by the voltage detection circuit 20, and forms the first power supply signal based on the measured voltage output by the voltage detection circuit 20 in the first charging phase of each charging cycle of the switching power supply chip. The first charging circuit 30 controls the chip power supply circuit 10 to be turned on and off according to the first power supply signal in the first charging phase of each charging cycle of the switching power supply chip, so that the switching power supply chip normally operates in the first charging phase.
As an example, as shown in fig. 3, the second charging circuit 40 is connected to the voltage detection circuit 20 and the chip power supply circuit 10, and the second charging circuit 40 obtains the measured voltage output by the voltage detection circuit 20, and forms the second power supply signal based on the measured voltage output by the voltage detection circuit 20 in the second charging phase of each charging cycle of the switching power supply chip. The second charging circuit 40 controls the chip power supply circuit 10 to be turned on and off according to the second power supply signal in a second charging phase of each charging cycle of the switching power supply chip, so that the switching power supply chip normally operates in the second charging phase.
In this embodiment, the switching power supply circuit uses the chip power supply circuit 10 to control the conduction of the power supply input terminal Vin and the chip power terminal VDD to supply power to the switching power supply chip without an auxiliary winding; the voltage detection circuit 20 is adopted to detect the actual measurement voltage of the power supply end VDD of the chip; the first charging circuit 30 forms a first power supply signal according to the actually measured voltage input by the voltage detection circuit 20 in the first charging stage of each charging cycle of the switching power supply chip, and controls the chip power supply circuit 10 to be switched on and off according to the first power supply signal; the second charging circuit 40 forms a second power supply signal according to the measured voltage input by the voltage detection circuit 20 in the second charging phase of each charging cycle of the switching power supply chip, and controls the chip power supply circuit 10 to be switched on and off according to the second power supply signal, so that the switching power supply circuit can ensure the normal work of the switching power supply chip in the charging cycle of the switching power supply chip without an auxiliary winding.
In one embodiment, as shown in fig. 3, the chip power supply circuit 10 includes a chip power supply switch Q1 and a current limiting tube Q2; the chip power supply switch tube Q1 is connected with the power supply input end Vin, the current limiting tube Q2, the first charging circuit 30 and the second charging circuit 40; the current-limiting tube Q2 is connected with the chip power supply switch tube Q1 and a chip power supply end VDD.
The chip power supply switch Q1 is a switch for turning on and off the chip power supply circuit 10. The current limiting tube Q2 is a device for preventing the chip power supply circuit 10 from being turned on, and the power supply input terminal Vin supplies a reverse current to the chip power supply terminal VDD through the chip power supply circuit 10.
As an example, the current limiting tube Q2 is connected to the chip power supply switch Q1 and the chip power supply terminal VDD, when the chip power supply circuit 10 is turned on, the power supply input terminal Vin is prevented from causing loss to the chip power supply switch Q1 by the reverse current of the chip power supply circuit 10 supplying power to the chip power supply terminal VDD, and the reliability of the chip power supply circuit 10 supplying power to the switch power supply chip is improved.
In this embodiment, the chip power supply switch Q1 is connected to the power supply input terminal Vin, the current limiting tube Q2, the first charging circuit 30 and the second charging circuit 40, and the chip power supply switch Q1 can control the chip power supply circuit 10 to be turned on or off by the first charging signal generated by the first charging circuit 30 or the second charging signal generated by the second charging circuit 40, so that the switching power supply circuit can ensure the normal operation of the switching power supply chip in the charging cycle of the switching power supply chip without the auxiliary winding. Further, the current limiting tube Q2 can prevent the reverse current of the power supply input end Vin to the power supply end VDD of the chip from causing loss to the chip power supply switch tube Q1 through the chip power supply circuit 10, and improve the reliability of the chip power supply circuit 10 to supply power to the switch power supply chip.
In one embodiment, as shown in fig. 3, the control terminal of the chip power switch Q1 is connected to the first charging circuit 30, the first connection terminal is connected to the power input terminal Vin, and the second connection terminal is connected to the current limiting tube Q2 and the second charging circuit 40.
Specifically, the chip power supply switch Q1 may be a transistor or a MOS transistor. As an example, the chip supply switch Q1 is a triode, the collector of the chip supply switch Q1 is connected to the supply input Vin, the base of the chip supply switch Q1 is connected to the first charging circuit 30, and the emitter of the chip supply switch Q1 is connected to the current limiting transistor Q2 and the second charging circuit 40. As another example, the chip supply switch Q1 is a MOS transistor, the drain of the chip supply switch Q1 is connected to the supply input terminal Vin, the gate of the chip supply switch Q1 is connected to the first charging circuit 30, and the source of the chip supply switch Q1 is connected to the current limiting transistor Q2 and the second charging circuit 40.
In this embodiment, the chip power supply switch Q1 is connected to the power supply input terminal Vin, the current limiting tube Q2, the first charging circuit 30 and the second charging circuit 40, and the chip power supply switch Q1 can control the chip power supply switch Q1 of the chip power supply circuit 10 to be turned on or off by the first charging signal generated by the first charging circuit 30 or the second charging signal generated by the second charging circuit 40, so that the switching power supply circuit can ensure the normal operation of the switching power supply chip in the charging period of the switching power supply chip without the auxiliary winding.
In one embodiment, as shown in fig. 2 and 3, the current limiting tube Q2 may be a current limiting diode, a current limiting transistor, or a current limiting MOS transistor. As an example, the current-limiting tube Q2 is a current-limiting diode, the positive electrode of the current-limiting tube Q2 is connected to the chip power supply switch Q1, and the negative electrode of the current-limiting tube Q2 is connected to the chip power supply terminal VDD. As another example, the current-limiting tube Q2 is a triode, the collector of the current-limiting tube Q2 is connected to the chip power supply switch Q1, the emitter of the current-limiting tube Q2 is connected to the chip power supply terminal VDD, and the base of the current-limiting tube Q2 is connected to the collector of the current-limiting tube Q2. As another example, the current-limiting tube Q2 is a MOS transistor, the drain of the current-limiting tube Q2 is connected to the chip power supply switch Q1, the source of the current-limiting tube Q2 is connected to the chip power supply terminal VDD, and the gate of the current-limiting tube Q2 is connected to the drain of the current-limiting tube Q2.
In this embodiment, the current-limiting tube Q2 may be a current-limiting diode, a current-limiting triode, or a current-limiting MOS transistor, the current-limiting tube Q2 is connected to the chip power supply switch Q1 and the chip power supply terminal VDD, when the chip power supply circuit 10 is turned on, the power supply input terminal Vin is prevented from causing loss to the chip power supply switch Q1 by a reverse current supplied to the chip power supply terminal VDD by the chip power supply circuit 10, and the reliability of the chip power supply circuit 10 in supplying power to the switch power supply is improved.
In one embodiment, as shown in fig. 3, the voltage detection circuit 20 includes a first voltage dividing resistor Ra, a second voltage dividing resistor Rb, and a third voltage dividing resistor Rc serially arranged between the chip power source terminal VDD and the ground terminal.
In this embodiment, the first voltage dividing resistor Ra, the second voltage dividing resistor Rb and the third voltage dividing resistor Rc are serially connected between the chip power source terminal VDD and the ground terminal, so as to divide the voltage of the chip power source terminal VDD, and the voltage detection circuit 20 obtains the actual measurement voltage of the chip power source terminal VDD through the voltage division processing of the first voltage dividing resistor Ra, the second voltage dividing resistor Rb and the third voltage dividing resistor Rc, so that the switching power source circuit performs the next processing on the actual measurement voltage corresponding to the chip power source terminal VDD, thereby ensuring the normal operation of the switching power source chip in the charging cycle of the switching power source chip without an auxiliary winding.
In one embodiment, as shown in fig. 3, the first charging circuit 30 includes a first comparator 31, a first logic gate 32, and a first control switch M1; the first comparator 31 is connected with the first voltage-dividing resistor Ra and the second voltage-dividing resistor Rb, and is configured to collect a first measured voltage between the first voltage-dividing resistor Ra and the second voltage-dividing resistor Rb in a first charging phase of each charging cycle of the switching power supply chip, and form a first power supply signal according to the first measured voltage and a first reference voltage; a first logic gate 32 connected to the first comparator 31 for forming a first charging signal according to the first power supply signal; and the first control switch tube M1 is connected to the first logic gate 32 and the chip power supply switch tube Q1, and is configured to control the chip power supply switch tube Q1 to be turned on or off according to the first charging signal.
The first logic gate 32 is a gate circuit for performing logic processing on multiple signals. The first logic gate 32 comprises an enable signal input and a supply signal input for deriving an enable signal and a first supply signal, respectively. The first logic gate 32 is configured to perform logic processing on the enable signal and the first power supply signal to form a first charging signal, and control the chip power supply switch Q1 to be turned on or off based on the first charging signal. The enable signal is a signal for logic processing with the first power supply signal. As an example, the first logic gate 32 may be a nand gate. The first measured voltage is a first measured voltage between the first and second divider resistors Ra and Rb.
Specifically, the first comparator 31 is connected to the first voltage-dividing resistor Ra and the second voltage-dividing resistor Rb, and the first comparator 31 collects a first measured voltage between the first voltage-dividing resistor Ra and the second voltage-dividing resistor Rb in a first charging phase of each charging cycle of the switching power supply chip, and compares the first measured voltage with a first reference voltage to form a first power supply signal. The first logic gate 32 forms a first charging signal according to the first power supply signal; the first control switch M1 controls the chip power switch Q1 to turn on or off according to the first charging signal. The first reference voltage is a voltage used for comparing with the first measured voltage.
As an example, during a first charging phase of each charging cycle of the switching power supply chip, the first comparator 31 compares a first measured voltage with a first reference voltage, and generates a first power supply signal when the measured voltage is smaller than the first reference voltage. The first logic gate 32 forms a first charging signal according to the first power supply signal and the enable signal obtained from the enable signal input terminal, and the first control switch tube M1 controls the chip power supply switch tube Q1 to be turned on according to the first charging signal to charge the switching power supply chip. In the first charging stage of each charging cycle of the switching power supply chip, when the measured voltage is greater than the first reference voltage, the first comparator 31 stops outputting the first power supply signal, the enable signal is inverted, the first logic gate 32 stops outputting the first charging signal, the first control switch tube M1 is turned off, the chip power supply switch tube Q1 is controlled to be turned off, and the switching power supply chip is stopped being charged.
In this embodiment, when the measured voltage is smaller than the first reference voltage in the first charging phase of each charging cycle of the switching power supply chip, the first control switch M1 controls the chip power supply switch Q1 to be turned on according to the first charging signal to charge the switching power supply chip; when the measured voltage is greater than the first reference voltage, the first comparator 31 stops outputting the first power supply signal, the enable signal is inverted, the first logic gate 32 stops outputting the first charging signal, the first control switch tube M1 is turned off, the chip power supply switch tube Q1 is controlled to be turned off, and the switching power supply chip is stopped being charged.
In one embodiment, as shown in fig. 3, the first charging circuit 30 further includes a first reference circuit ref1, and the first reference circuit ref1 is connected to the first comparator 31 for providing a first reference voltage to the first comparator 31.
In this embodiment, the first comparator 31 can compare the first reference voltage provided by the first reference circuit ref1 with the first measured voltage to form a first power supply signal, and the first logic gate 32 forms a first charging signal according to the first power supply signal; the first control switch tube M1 controls the chip power supply switch tube Q1 to be switched on or switched off according to the first charging signal, so that the normal operation of the switching power supply chip is ensured when the first charging phase of each charging cycle of the switching power supply chip is in the condition of no auxiliary winding.
In one embodiment, as shown in fig. 3, the second charging circuit 40 includes a second comparator 41, a second logic gate 42, and a second control switch M2; the second comparator 41 is connected to the second voltage-dividing resistor Rb and the third voltage-dividing resistor Rc, and configured to collect a second measured voltage between the second voltage-dividing resistor Rb and the third voltage-dividing resistor Rc in a second charging phase of each charging cycle of the switching power supply chip, and form a second power supply signal according to the second measured voltage and a second reference voltage; a second logic gate 42, connected to the second comparator 41, for forming a second charging signal according to the second power supply signal; and the second control switch M2 is connected to the second logic gate 42 and the chip power supply switch Q1, and is configured to control the chip power supply switch Q1 to turn on or off according to the second charging signal.
The second logic gate 42 is a gate circuit for performing logic processing on multiple signals. The second logic gate 42 comprises a supply signal input and a control signal input for deriving a second supply signal and a control signal, respectively. The second logic gate 42 is used for performing logic processing on the control signal and the second power supply signal to form a second charging signal, and controlling the chip power supply switch Q1 to be turned on or off based on the second charging signal. As an example, the second logic gate 42 may be an and nor gate circuit. The second measured voltage is a measured voltage between the second and third voltage dividing resistors Rb and Rc. The second reference voltage is a voltage for comparison with the second measured voltage.
Specifically, the second comparator 41 is connected to the second voltage-dividing resistor Rb and the second voltage-dividing resistor Rb, and the second comparator 41 collects a second measured voltage between the second voltage-dividing resistor Rb and the second voltage-dividing resistor Rb in a second charging phase of each charging cycle of the switching power supply chip, and compares the second measured voltage with a second reference voltage to form a second power supply signal. The second logic gate 42 forms a second charging signal according to the second power supply signal; the second control switch M2 controls the on/off of the chip power supply switch Q1 according to the second charging signal.
As an example, as shown in fig. 4, the control signals are PUL _ pre and PUL. In the second charging phase of each charging cycle of the switching power supply chip, the second comparator 41 compares the second measured voltage with the second reference voltage, and generates a second power supply signal when the measured voltage is smaller than the second reference voltage. The second logic gate 42 forms a second charging signal according to the second power supply signal and the enable signal obtained from the enable signal input terminal, and the second control switch tube M2 controls the chip power supply switch tube Q1 to be turned on according to the second charging signal to charge the switching power supply chip. In the second charging stage of each charging cycle of the switching power supply chip, when the measured voltage is greater than the second reference voltage, the second comparator 41 stops outputting the second power supply signal, the control signal is inverted, the second logic gate 42 stops outputting the second charging signal, the second control switch tube M2 is turned off, the control chip power supply switch tube Q1 is turned off, and the switching power supply chip is stopped being charged.
In this embodiment, when the measured voltage is smaller than the second reference voltage in the second charging phase of each charging cycle of the switching power supply chip, the second comparator 41 outputs a second charging signal, and the second control switch M2 controls the chip power supply switch Q1 to be turned on according to the second charging signal to charge the switching power supply chip; when the measured voltage is greater than the second reference voltage, the second ssss comparator 41 stops outputting the second power supply signal, the control signal is inverted, the second logic gate 42 stops outputting the second charging signal, the second control switch M2 is turned off, the chip power supply switch Q1 is turned off, and the switching power supply chip is stopped being charged. The normal work of the switching power supply chip is ensured when the second charging stage of each charging cycle of the switching power supply chip is in the condition of no auxiliary winding.
In one embodiment, as shown in fig. 3, the second charging circuit 40 further includes a second reference circuit ref2, and the second reference circuit ref2 is connected to the second comparator 41 for providing a second reference voltage to the second comparator 41.
In this embodiment, the second comparator 41 can compare the second reference voltage provided by the second reference circuit ref2 with the second measured voltage to form a second power supply signal, and the second logic gate 42 forms a second charging signal according to the second power supply signal; and the second control switch tube M2 controls the chip power supply switch tube Q1 to be switched on or switched off according to the second charging signal, so that the normal work of the switching power supply chip is ensured in the second charging stage of each charging period of the switching power supply chip under the condition of no auxiliary winding.
In one embodiment, the second charging circuit 40 further comprises a blanking time circuit 43 connected to the second logic gate 42 for providing a blanking period signal to the second logic gate 42; the second logic gate 42 forms a second charging signal based on the second supply signal and the blanking period signal.
The blanking time circuit 43 is a circuit for avoiding the interference signal from affecting the accuracy of the second charging signal output by the second logic gate 42. The blanking period signal is a time signal for masking the interference signal.
As an example, as shown in fig. 5 and 6, when the measured voltage of the power supply terminal VDD of the chip is smaller than the second reference voltage, the second comparator 41 outputs the second charging signal according to the blanking time signal, and the second control switch transistor M2 controls the chip power supply switch transistor Q1 to be turned on to charge the switching power supply chip according to the second charging signal during the blanking time, wherein the CS pin is the current detection pin of the switching power supply chip.
In the present embodiment, the blanking time circuit 43 supplies the blanking period signal to the second logic gate 42; the second logic gate 42 forms a second charging signal based on the second supply signal and the blanking period signal. And the second control switch tube M2 controls the conduction of the chip power supply switch tube Q1 to charge the switch power supply chip according to the second charging signal in the blanking time so as to ensure that the actually measured voltage of the chip power supply end VDD can be kept stable.
The above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A switching power supply circuit comprises a switching power supply chip, and is characterized by further comprising a chip power supply circuit, a voltage detection circuit, a first charging circuit and a second charging circuit;
the chip power supply circuit is connected with a power supply input end and a chip power end of the switching power supply chip and is used for controlling the connection and disconnection of the power supply input end and the chip power end;
the voltage detection circuit is connected with the chip power supply circuit and is used for detecting the actually measured voltage of the power end of the chip;
the first charging circuit is connected with the voltage detection circuit and the chip power supply circuit and is used for forming a first power supply signal according to the actually measured voltage input by the voltage detection circuit in the first charging stage of each charging period of the switching power supply chip and controlling the chip power supply circuit to be switched on and switched off according to the first power supply signal;
and the second charging circuit is connected with the voltage detection circuit and the chip power supply circuit and is used for forming a second power supply signal according to the actually measured voltage input by the voltage detection circuit in a second charging stage of each charging period of the switching power supply chip and controlling the chip power supply circuit to be switched on and switched off according to the second power supply signal.
2. The switching power supply circuit according to claim 1, wherein the chip power supply circuit includes a chip power supply switching tube and a current limiting tube;
the chip power supply switch tube is connected with the power supply input end, the current limiting tube, the first charging circuit and the second charging circuit;
the current limiting tube is connected with the chip power supply switch tube and the chip power end.
3. The switching power supply circuit according to claim 2, wherein the control terminal of the chip power supply switching tube is connected to the first charging circuit, the first connection terminal is connected to the power supply input terminal, and the second connection terminal is connected to the current limiting tube and the second charging circuit.
4. The switching power supply circuit according to claim 2, wherein the current limiting tube is a current limiting diode, an anode of the current limiting tube is connected to the chip power supply switching tube, and a cathode of the current limiting tube is connected to the chip power supply terminal;
or the current-limiting tube is a triode, the collector of the current-limiting tube is connected with the chip power supply switch tube, the emitter of the current-limiting tube is connected with the power end of the chip, and the base of the current-limiting tube is connected with the collector of the current-limiting tube;
or the current-limiting tube is an MOS tube, the drain electrode of the current-limiting tube is connected with the chip power supply switch tube, the source electrode of the current-limiting tube is connected with the chip power supply end, and the grid electrode of the current-limiting tube is connected with the drain electrode of the current-limiting tube.
5. The switching power supply circuit according to claim 1, wherein the voltage detection circuit includes a first voltage-dividing resistor, a second voltage-dividing resistor, and a third voltage-dividing resistor arranged in series between a power supply terminal and a ground terminal of the chip.
6. The switching power supply circuit according to claim 5, wherein the first charging circuit comprises a first comparator, a first logic gate and a first control switch tube;
the first comparator is connected with the first voltage-dividing resistor and the second voltage-dividing resistor, and is configured to collect a first measured voltage between the first voltage-dividing resistor and the second voltage-dividing resistor in a first charging stage of each charging cycle of the switching power supply chip, and form a first power supply signal according to the first measured voltage and a first reference voltage;
the first logic gate is connected with the first comparator and used for forming a first charging signal according to the first power supply signal;
and the first control switch tube is connected with the first logic gate and the chip power supply switch tube and is used for controlling the chip power supply switch tube to be switched on or switched off according to the first charging signal.
7. The switching power supply circuit according to claim 6, wherein said first charging circuit further comprises a first reference circuit connected to said first comparator for providing a first reference voltage to said first comparator.
8. The switching power supply circuit according to claim 5, wherein the second charging circuit comprises a second comparator, a second logic gate and a second control switch tube;
the second comparator is connected with the second voltage-dividing resistor and the third voltage-dividing resistor, and is configured to collect a second measured voltage between the second voltage-dividing resistor and the third voltage-dividing resistor in a second charging stage of each charging cycle of the switching power supply chip, and form a second power supply signal according to the second measured voltage and a second reference voltage;
the second logic gate is connected with the second comparator and used for forming a second charging signal according to the second power supply signal;
and the second control switch tube is connected with the second logic gate and the chip power supply switch tube and is used for controlling the chip power supply switch tube to be switched on or switched off according to the second charging signal.
9. The switching power supply circuit according to claim 8, wherein said second charging circuit further comprises a second reference circuit connected to said second comparator for providing a second reference voltage to said second comparator.
10. The switching power supply circuit according to claim 9, wherein said second charging circuit further comprises a blanking time circuit connected to said second logic gate for providing a blanking period signal to said second logic gate; the second logic gate forms the second charging signal according to the second power supply signal and the blanking period signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021529658.9U CN213027823U (en) | 2020-07-28 | 2020-07-28 | Switching power supply circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021529658.9U CN213027823U (en) | 2020-07-28 | 2020-07-28 | Switching power supply circuit |
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| Publication Number | Publication Date |
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| CN213027823U true CN213027823U (en) | 2021-04-20 |
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| CN202021529658.9U Active CN213027823U (en) | 2020-07-28 | 2020-07-28 | Switching power supply circuit |
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| CN (1) | CN213027823U (en) |
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Address after: Building 3A28, Smart Home Phase II, No. 76 Baohe Avenue, Baolong Community, Baolong Street, Longgang District, Shenzhen City, Guangdong Province, 518000 Patentee after: Shenzhen Chuangxin Microelectronics Co.,Ltd. Address before: 518000 Room 401, block a, Longgang smart home, 76 Baohe Avenue, Baolong community, Baolong street, Longgang District, Shenzhen City, Guangdong Province Patentee before: SHENZHEN CHUANGXINWEI MICROELECTRONICS Co.,Ltd. |
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