CN113991611A - Switching power supply and protection circuit thereof - Google Patents
Switching power supply and protection circuit thereof Download PDFInfo
- Publication number
- CN113991611A CN113991611A CN202111470200.XA CN202111470200A CN113991611A CN 113991611 A CN113991611 A CN 113991611A CN 202111470200 A CN202111470200 A CN 202111470200A CN 113991611 A CN113991611 A CN 113991611A
- Authority
- CN
- China
- Prior art keywords
- power supply
- pull
- resistor
- switching
- control chip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000002159 abnormal effect Effects 0.000 claims abstract description 32
- 238000004804 winding Methods 0.000 claims description 22
- 239000003990 capacitor Substances 0.000 claims description 17
- 238000001514 detection method Methods 0.000 claims description 10
- 230000000087 stabilizing effect Effects 0.000 claims description 6
- 208000031361 Hiccup Diseases 0.000 abstract description 39
- 238000000034 method Methods 0.000 abstract description 15
- 238000009825 accumulation Methods 0.000 abstract description 8
- 102100036285 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial Human genes 0.000 description 11
- 101000875403 Homo sapiens 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial Proteins 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000002035 prolonged effect Effects 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 2
- 238000013021 overheating Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/06—Details with automatic reconnection
- H02H3/063—Details concerning the co-operation of many similar arrangements, e.g. in a network
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention provides a switching power supply and a protection circuit thereof, wherein the protection circuit is arranged between a power supply pin of a control chip in the switching power supply and the ground through a pull-down execution unit of the protection circuit; when the switching power supply has an output abnormal fault, the pull-down control unit controls the pull-down execution unit to be switched into a channel, and further the voltage of a power supply pin of the control chip is pulled down to the ground, so that the power supply pin of the control chip is charged from 0V to the starting point of the control chip in each time in the hiccup protection mode; compare in prior art from the undervoltage protection point of control chip to the charging process between the starting point, this application is showing and has lengthened the hiccup cycle, can avoid because the hiccup cycle is too short, and the power device that causes is because of the final heat accumulation of frequent machine-starting damages.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a switching power supply and a protection circuit thereof.
Background
The switching power supply is an AC-DC or DC-DC conversion unit, and is widely used in the industrial field due to its high efficiency, small size, and high reliability. The switching power supply is used as an auxiliary power supply unit of the system, and is stable and reliable, so that when abnormal faults such as overcurrent, short circuit and overvoltage occur in the output of the switching power supply, the switching power supply needs to be protected quickly and reliably.
In the existing switching power supply, when a control chip detects that the switching power supply has the output abnormal fault, the control chip performs wave sealing processing to stop the switching power supply to stop outputting, and simultaneously, the power supply connected with a VDD pin of the control chip is disconnected, and then the VDD power supply voltage is continuously reduced; when the VDD supply voltage drops to the undervoltage protection point VDD of the control chipUVLOThereafter, the switching power supply is turned off and enters a hiccup protection mode (hippoup). If the input of the switch power supply is not powered down, the switch power supply can restart, and the VDD power supply voltage is from VDDUVLOCharging to the starting point VDDONThen, the control chip restarts working, and when detecting that the output abnormal fault of the switching power supply is not relieved, the control chip seals the wave again; this is repeated until the output abnormality is resolved. Under normal conditions, the switching power supply enters a hiccup protection mode, and power limitation can be realized when the switching power supply has an output abnormal fault, so that power devices (a primary side MOS (metal oxide semiconductor) tube and a secondary side diode) in the switching power supply are protected from being damaged due to overstress or overheating.
In practical applications, however, in the hiccup protection mode, the hiccup period, i.e. the time interval between two starts of the switching power supply, is usually short; especially, under the condition of high-voltage input, the VDD power supply voltage can be quickly charged to VDDON. For a high-voltage input high-power switching power supply, the hiccup period is too short, so that the power device is easily damaged due to frequent starting and final heat accumulation in the hiccup protection mode.
Disclosure of Invention
In view of the above, the present invention provides a switching power supply and a protection circuit thereof to prolong the hiccup period in the hiccup protection mode and avoid the damage of the power device due to the final thermal accumulation caused by frequent machine-up.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
the invention provides a protection circuit of a switching power supply in a first aspect, comprising: the pull-down power supply unit comprises a pull-down execution unit, a pull-down control unit and a pull-down power supply unit; wherein:
the pull-down execution unit is arranged between a power supply pin of a control chip in the switch power supply and the ground;
the output end of the pull-down control unit is connected with the control end of the pull-down execution unit and is used for controlling the pull-down execution unit to be switched into a path and maintaining a preset time length when the switching power supply has an output abnormal fault;
the pull-down power supply unit is used for supplying power to the protection circuit.
Optionally, the pull-down execution unit includes: the circuit comprises a first resistor, a second resistor and a first switching tube;
one end of the first resistor is connected with a power supply pin of the control chip;
the other end of the first resistor is connected with the input end of the first switching tube;
the output end of the first switching tube is grounded;
the control end of the first switching tube is used as the control end of the pull-down execution unit;
the second resistor is arranged between the control end and the output end of the first switch tube.
Optionally, the pull-down control unit includes: the third resistor, the fourth resistor and the second switch tube;
one end of the third resistor receives the power supply voltage output by the pull-down power supply unit;
the other end of the third resistor is connected with the input end of the second switching tube, and the connection point is used as the output end of the pull-down control unit;
the output end of the second switching tube is grounded;
the second switch tube control end receives a shutdown/fault signal; when the switching power supply has an output abnormal fault, the shutdown/fault signal controls the second switching tube to be switched off;
the fourth resistor is arranged between the control end and the output end of the second switch tube.
Optionally, the pull-down control unit includes: a fifth resistor, a sixth resistor and a comparator;
the output end of the comparator is used as the output end of the pull-down control unit;
a positive input end of the comparator is connected with one end of the fifth resistor and one end of the sixth resistor;
the other end of the fifth resistor receives the power supply voltage output by the pull-down power supply unit, and the other end of the sixth resistor is grounded;
the negative input end of the comparator receives a shutdown/fault signal; when the switching power supply has output abnormal faults, the shutdown/fault signal enables the comparator to output a conduction control signal.
Optionally, the shutdown/fault signal is derived from: and the power-off state pin of the control chip or the power-off state detection circuit of the switching power supply.
Optionally, the pull-down power supply unit takes power from an auxiliary winding of a switching transformer in the switching power supply.
Optionally, the pull-down power supply unit and the power supply pin of the control chip take power from the same auxiliary winding.
Optionally, the pull-down power supply unit includes: a diode and a capacitor;
the anode of the diode receives the power supply voltage of the auxiliary winding;
the cathode of the diode is grounded through the capacitor;
and the cathode of the diode provides a power supply voltage for the pull-down control unit.
Optionally, a voltage stabilizing circuit is further disposed between the pull-down power supply unit and the auxiliary winding.
The second aspect of the present invention also provides a switching power supply, including: a main circuit, a control chip, a detection circuit and a protection circuit of the switching power supply as described in any one of the paragraphs above of the first aspect; wherein:
the detection circuit is used for detecting the voltage and/or the current of the input end and/or the output end of the main circuit and outputting the voltage and/or the current to the control chip;
the control chip is used for realizing control and protection of the main circuit;
the protection circuit is used for pulling down the voltage of the power supply pin of the control chip to the ground when the switching power supply has output abnormal faults.
The protection circuit of the switching power supply is arranged between a power supply pin of a control chip in the switching power supply and the ground through the pull-down execution unit; when the switching power supply has an output abnormal fault, the pull-down control unit controls the pull-down execution unit to be switched to a channel, and further the voltage of the power supply pin of the control chip is pulled down to the ground, so that in the hiccup protection mode, after the voltage of the power supply pin of the control chip is pulled down to the ground for a preset time, the power supply pin of the control chip is charged from 0V to the starting point of the control chip; compare from the charging process between undervoltage protection point to the starting point among the prior art, this application is showing and has lengthened the hiccup cycle, can avoid because the hiccup cycle is too short, and the power device that causes damages because of the final heat accumulation of frequent machine-starting.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a protection circuit of a switching power supply according to an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating a connection relationship between a power supply pin of a control chip of a switching power supply and other circuits according to an embodiment of the present invention;
fig. 3 and fig. 4 are two circuit diagrams of the protection circuit of the switching power supply according to the embodiment of the invention;
FIG. 5 is a circuit diagram of a voltage regulator circuit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a switching power supply according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The invention provides a protection circuit of a switching power supply, which is used for prolonging a hiccup period in a hiccup protection mode and avoiding the damage of a power device caused by the final heat accumulation due to frequent starting.
As shown in fig. 1, the protection circuit of the switching power supply includes: a pull-down execution unit 103, a pull-down control unit 102, and a pull-down power supply unit 101; wherein:
the pull-down execution unit 103 is arranged between a power supply pin VDD of a control chip in the switching power supply and a ground GND; when the pull-down execution unit 103 is open, it has no influence on the voltage at the power supply pin VDD, which is the voltage VDD1 provided by the power supply of the control chip; when the pull-down execution unit 103 is turned on, the voltage at the power supply pin VDD is pulled down to ground.
The output end of the pull-down control unit 102 is connected with the control end of the pull-down execution unit 103; when the switching power supply normally works, no instruction is sent out by the pull-down control unit 102; however, when the switching power supply has an output abnormal fault, such as an output overcurrent, a short circuit, an overvoltage and other abnormal faults, the pull-down control unit 102 sends a pull-down instruction Shutdown to the pull-down execution unit 103, and controls the pull-down execution unit 103 to switch to a path, so as to pull down the voltage at the power supply pin VDD to ground and maintain the preset time duration.
The pull-down power supply unit 101 is used for supplying power to the protection circuit; the energy storage device can store energy when the switching power supply works normally, and supply power to the pull-down control unit 102 when the power supply has an output abnormal fault.
The specific working principle is as follows:
referring to fig. 2, when the control chip detects that the switching power supply has the output abnormal fault, the wave-sealing process is performed, that is, the PWM signal is no longer sent to the MOS transistor VT1 connected to the primary winding S1 of the switching transformer 201 in the main circuit of the switching power supply, so that the MOS transistor VT1 stops working.
In the prior art, the MOS transistor VT1 needs to be relied on to stop working, so that the secondary winding S2 of the switching transformer stops outputting to the rear stage, and the auxiliary winding S3 of the switching transformer stops supplying power to the power supply pin VDD of the control chip; then, along with the discharge of the external capacitor of the power supply pin VDD, the voltage VDD1 of the power supply pin VDD is continuously reduced; when the voltage of the power supply pin VDD drops to the undervoltage protection point VDD of the control chipUVLOThereafter, the switching power supply is shut down and enters the hiccup protection mode. Under the condition that the input of the switching power supply is not powered down, the power supply pin VDD of the control chip receives the power supply of the starting circuit 202, and the voltage of the power supply pin VDD is from VDDUVLOCharging to the starting point VDDONThen, the control chip restarts working, and when detecting that the power output abnormal fault is not released, the control chip seals the wave again; the steps are repeated until the power output abnormal fault is relieved.
In this embodiment, when the control chip detects that the switching power supply has the output abnormal fault, the pull-down control unit 102 controls the pull-down execution unit 103 to switch to a pass, and directly pulls down the voltage at the power supply pin VDD to the ground, that is, 0V, so that the control chip can perform under-voltage protection and enter a hiccup protection mode; then, the pull-down power supply unit 101 discharges, and after a preset time period, the pull-down control unit 102 controls the pull-down execution unit 103 to return to the open circuit. Under the condition that the input of the switching power supply is not powered down, a power supply pin VDD of the control chip receives power supply of the starting circuit 202, and the voltage of the power supply pin VDD is charged from 0V to a starting point VDDONThen, the control chip restarts working, and when detecting that the power output abnormal fault is not released, the control chip seals the wave again; the steps are repeated until the power output abnormal fault is relieved.
Therefore, the present embodiment not only enables the switching power supply to enter the hiccup protection mode, and implements power limitation for output abnormal fault, thereby protecting the MOS transistor VT1 and the secondary side diode (not shown in fig. 2) from being damaged by overstress or overheating; in the hiccup protection mode, each time the charging process of the power supply pin VDD of the control chip is started from 0V to the starting point VDDONFinishing; compared with the slave undervoltage protection point VDD in the prior artUVLOTo the starting point VDDONThe charging process between, this embodiment is showing and has lengthened the hiccup cycle, can avoid because the hiccup cycle is too short, and the power device that causes is because of the final heat accumulation of frequent machine-starting damages.
It is worth noting that there is also a way in the prior art to make the hiccup protection time longer by increasing the starting resistance/capacitance of the start-up circuit 202; however, the power supply startup time is also prolonged by the method, so that the use experience of a user is reduced, and even the power supply time sequence of the whole system is influenced. And this protection circuit that this embodiment provided only under hiccup protection mode, just can prolong hiccup cycle to do not influence the length of time of normal machine-starting, more can not bring the influence to complete machine system power supply time sequence, do benefit to popularization and application.
On the basis of the previous embodiment, referring to fig. 3, the present embodiment provides a specific implementation form of the pull-down execution unit 103, including: the circuit comprises a first resistor R1, a second resistor R2 and a first switch tube Q1; wherein:
one end of the first resistor R1 is connected with a power supply pin VDD of the control chip; the other end of the first resistor R1 is connected with the input end of a first switch tube Q1; the output end of the first switching tube Q1 is grounded GND; the control end of the first switching tube Q1 is used as the control end of the pull-down execution unit 103; the second resistor R2 is disposed between the control terminal and the output terminal of the first switch Q1.
In practical applications, the second resistor R2 may also be connected in parallel with a capacitor, which is not shown in fig. 3; in addition, the first resistor R1 and the second resistor R2 may be a series-parallel connection of a plurality of resistors, and the resistance values thereof may be determined according to the actual application environment, and are within the protection scope of the present application.
In addition, various implementation forms are possible for the pull-down control unit 102, and fig. 3 and 4 are two specific examples respectively; as shown in fig. 3, the pull-down control unit 102 includes: a third resistor R3, a fourth resistor R4 and a second switch tube Q2; wherein:
one end of the third resistor R3 receives the supply voltage VDD2 output by the pull-down power supply unit 101; the other end of the third resistor R3 is connected to the input end of the second switch tube Q2, and the connection point is used as the output end of the pull-down control unit 102; the output end of the second switch tube Q2 is grounded GND; the control end of the second switch tube Q2 receives a shutdown/fault signal VREF; when the switching power supply has an output abnormal fault, the shutdown/fault signal VREF controls the second switching tube Q2 to be switched off; the fourth resistor R4 is disposed between the control terminal and the output terminal of the second switch Q2.
Alternatively, as shown in fig. 4, the pull-down control unit 102 includes: a fifth resistor R5, a sixth resistor R6 and a comparator U1; wherein:
the output terminal of the comparator U1 serves as the output terminal of the pull-down control unit 102; a positive input end of the comparator U1 is connected to one end of the fifth resistor R5 and one end of the sixth resistor R6; the other end of the fifth resistor R5 receives the supply voltage VDD2 output by the pull-down power supply unit 101, and the other end of the sixth resistor R6 is grounded to GND; the negative input of comparator U1 receives shutdown/fault signal VREF; when the switching power supply has an output abnormal fault, the shutdown/fault signal VREF causes the comparator U1 to output a turn-on control signal.
It should be noted that the control chip may have a shutdown state pin, so that when the control chip detects that the switching power supply has an output abnormal fault and causes the control chip to perform undervoltage shutdown, the control chip directly outputs the shutdown/fault signal VREF, and further controls the pull-down execution unit 103 to switch to the path. Or, when the control chip does not have the power-off state pin, whether the MOS transistor VT1 stops working or not and whether the control chip is in an under-voltage power-off state or not can be detected through an additionally arranged power-off state detection circuit; the shutdown state detection circuit may specifically rectify a PWM signal output from the control chip to the MOS transistor VT1, determine a voltage after rectification, and if the voltage is 0V, indicate that the switching power supply has an output abnormal fault and the control chip is in a wave-sealing state.
It should be further noted that the pull-down power supply unit 101 may obtain power from an auxiliary winding of the switching transformer, such as S3 shown in fig. 2 to 4, that is, the pull-down power supply unit 101 and the power supply pin VDD of the control chip obtain power from the same auxiliary winding S3; in practical applications, the pull-down power supply unit 101 may also be another single auxiliary winding (not shown), and even other auxiliary power supplies may be used to supply power to the pull-down power supply unit 101; all within the scope of protection of the present application, depending on the specific application environment.
As shown in fig. 3 and 4, the pull-down power supply unit 101 includes: a first diode D1 and a first capacitor C1; wherein the anode of the first diode D1 receives a corresponding supply voltage; the cathode of the first diode D1 is grounded GND through a first capacitor C1; the cathode of the first diode D1 provides the pull-down control unit 102 with the supply voltage VDD 2. After the pull-down control unit 102 controls the pull-down execution unit 103 to switch to the on state, the first capacitor C1 starts to discharge with the loss of power of the auxiliary winding S3, and after a preset time period, the supply voltage VDD2 becomes a low level, so that the pull-down control unit 102 shown in fig. 3 or fig. 4 controls the pull-down execution unit 103 to return to the off state; that is, the predetermined time period may be varied by adjusting the specific parameter setting of the first capacitor C1. Similarly, the power supply 203 of the control chip includes: a second diode D2 and a second capacitor C2; wherein the anode of the second diode D2 receives a corresponding supply voltage; the cathode of the second diode D2 is connected to the ground GND through the second capacitor C2; the cathode of the second diode D2 provides the supply voltage VDD1 for the control chip. In fig. 3 and fig. 4, the auxiliary winding S3 is shown passing through the fourth diode D4 and the fourth capacitor C4 to provide the power supply voltage for the pull-down power supply unit 101 and the power supply 203.
Preferably, a voltage stabilizing circuit 204 is further disposed between the pull-down power supply unit 101 and the auxiliary winding S3. The voltage stabilizing circuit 204 can stabilize the voltage provided by the auxiliary winding S3 to a constant value required by a later stage; it specifically includes what is shown in fig. 5: a third switch tube Q3, a voltage reference chip TL 431U 1, a third capacitor C3, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10; the input end of the third switching tube Q3 is connected with one end of a seventh resistor R7, and the connection point is connected with the cathode of a fourth diode D4 connected with the same-name end of the auxiliary winding S3; a fourth capacitor C4 is connected between the fourth diode D4 and the ground; a control end of the third switching tube Q3 is connected to the other end of the seventh resistor R7, one end of the third capacitor C3 and the negative electrode of the voltage reference chip TL 431U 1; the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are sequentially connected in series, and the other end of the eighth resistor R8 is connected with the pull-down power supply unit 101 and the power supply 203 of the control chip; the other end of the tenth resistor R10 is grounded with the anode of the voltage reference chip TL 431U 1; the other end of the third capacitor C3 is connected to the reference terminal of the voltage reference chip TL 431U 1 and the connection point of the ninth resistor R9 and the tenth resistor R10. Fig. 5 shows only one specific example of the voltage stabilization method, but is not limited thereto.
The auxiliary winding S3 of the main power transformer outputs through the fourth diode D4, and can further stabilize the voltage through the voltage stabilizing link; the power supply pin VDD of the control chip is then supplied with the power supply voltage VDD1 through the power supply 203, and the pull-down control unit 102 is also supplied with the power supply circuit VDD2 through the pull-down power supply unit 101. This configuration can save the auxiliary winding, and can make the power supply 203 and the pull-down power supply unit 101 share the same voltage stabilizing circuit 204, which is beneficial to reduce the cost, but is not limited thereto.
For the structure shown in fig. 3, the specific working principle is as follows:
when the switching power supply normally works, the Shutdown/fault signal VREF is at a high level, for example, 5V, at this time, the second switching tube Q2 is closed, no instruction is issued by the pull-down control unit 102, at this time, Shutdown is a low level signal, so that the first switching tube Q1 in the pull-down execution unit 103 is open, and there is no influence on the supply voltage VDD1 of the control chip.
When the switching power supply has output abnormal fault, the control chip seals waves, and the power supply voltage VDD1 of the control chip is reduced to VDDUVLOEntering a hiccup protection mode; then, the Shutdown/fault signal VREF is switched to a low level, for example, 0V, the second switching tube Q2 is turned off, the pull-down control unit 102 issues a pull-down instruction to the pull-down execution unit 103, at this time, Shutdown is a high level signal, so that the first switching tube Q1 in the pull-down execution unit 103 is switched to be closed, the circuit is switched to be a pass, the power supply voltage VDD1 of the control chip is pulled down to 0V, and the power supply voltage 1 of the control chip starts to charge from 0V in the hiccup protection mode, so as to prolong the hiccup period.
For the structure shown in fig. 4, the specific working principle is as follows:
the pull-down control unit 102 divides the supply voltage VDD2 provided by the pull-down power supply unit 101 to generate VDD2/K, where K is a division coefficient.
When the switching power supply normally works, the Shutdown/fault signal VREF is at a high level, for example, 5V, and the voltage division coefficient K is selected reasonably, so that VDD2/K is lower than VREF, for example, VDD2/K is 2.5V, VREF is 5V, so that the comparator U1 outputs a low level, no instruction is issued, Shutdown is a low level signal at this time, and then the first switch tube Q1 in the pull-down execution unit 103 is turned off, and there is no influence on the supply voltage VDD1 of the control chip.
In a switching power supplyWhen the output abnormal fault occurs, the control chip seals the wave, and the power supply voltage VDD1 is reduced to VDDUVLOEntering a hiccup protection mode; then, the power-off/fault signal VREF is switched to a low level, for example, 0V, at this time, VDD2/K is higher than VREF, for example, VDD2/K is 2.5V, VREF is 0V, so that the comparator U1 outputs a high level, the pull-down execution unit 103 issues a pull-down instruction, at this time, Shutdown is a high level signal, further, the first switch Q1 in the pull-down execution unit 103 is switched to be closed, the execution circuit is switched to be in a pass operation, the power supply voltage VDD1 of the control chip is pulled down to 0V, so that in the hiccup protection mode, the power supply voltage VDD1 of the control chip is charged from 0V, and the hiccup period is prolonged.
No matter which structure is adopted, the voltage of the power supply pin VDD of the control chip can be charged from 0V to VDD under the condition that the input of the switching power supply is not powered down and the hiccup protection modeONIn (1). Compare the traditional scheme that provides in prior art like this, the hiccup cycle can show the extension, can effectively solve high-voltage high-power switching power supply under hiccup protection mode, because of hiccup cycle is too short and the problem of frequent machine-starting final heat accumulation and damage.
Another embodiment of the present invention further provides a switching power supply, as shown in fig. 6, specifically including: a main circuit, a control chip, a detection circuit (not shown in the figure) and a protection circuit. Wherein:
the main circuit can be an AC-DC conversion circuit, a DC-DC conversion circuit or an AC-AC conversion circuit, the topology of the main circuit can be in the form of forward excitation, flyback and the like, only the switching transformer 201 and the switching tube VT1 are shown in fig. 6, the end with the same name of the transformer winding is not labeled, and the network connected with the source electrode of the switching tube VT1 is not shown; the former stage of the switching transformer 201 can also be provided with corresponding input filtering, conversion topology and the like, and the latter stage of the switching transformer 201 can also be provided with corresponding conversion topology, output filtering and the like, which are determined according to the specific application environment and are all within the protection scope of the application; in addition, fig. 6 only illustrates the start-up circuit 202, but the present invention is not limited thereto, and other solutions in the prior art may also be adopted.
The detection circuit is used for detecting the voltage and/or the current of the input end and/or the output end of the main circuit and outputting the voltage and/or the current to the control chip so as to be used for the control chip to perform calculation, other processing and the like.
The control chip is used for realizing control and protection of the main circuit; the control function at least comprises PWM control of a switching tube VT1 connected with a switching transformer in the main circuit, and the protection function at least comprises abnormal fault protection of overcurrent, short circuit, overvoltage and the like of the output of the main circuit.
The protection circuit is used for pulling down the voltage of a power supply pin VDD of the control chip to the ground when the switching power supply has an output abnormal fault. The specific structure and the working principle of the protection circuit can be obtained by referring to the above embodiments, and are not described in detail herein.
Through adding this protection circuit, when the power output fault that appears unusually, after the control chip carries out the encapsulation and handles, this protection circuit also can act for the voltage of control chip's power supply pin VDD can be pulled down to ground (0V), gets into hiccup protection mode, and its hiccup cycle is from 0V charge to VDDONThe hiccup period is obviously prolonged, and the damage of the power device caused by frequent starting and final thermal accumulation due to too short hiccup period can be avoided.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the above description of the disclosed embodiments, the features described in the embodiments in this specification may be replaced or combined with each other to enable those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A protection circuit for a switching power supply, comprising: the pull-down power supply unit comprises a pull-down execution unit, a pull-down control unit and a pull-down power supply unit; wherein:
the pull-down execution unit is arranged between a power supply pin of a control chip in the switch power supply and the ground;
the output end of the pull-down control unit is connected with the control end of the pull-down execution unit and is used for controlling the pull-down execution unit to be switched into a path and maintaining a preset time length when the switching power supply has an output abnormal fault;
the pull-down power supply unit is used for supplying power to the protection circuit.
2. The protection circuit of claim 1, wherein the pull-down execution unit comprises: the circuit comprises a first resistor, a second resistor and a first switching tube;
one end of the first resistor is connected with a power supply pin of the control chip;
the other end of the first resistor is connected with the input end of the first switching tube;
the output end of the first switching tube is grounded;
the control end of the first switching tube is used as the control end of the pull-down execution unit;
the second resistor is arranged between the control end and the output end of the first switch tube.
3. The protection circuit of the switching power supply according to claim 1, wherein the pull-down control unit comprises: the third resistor, the fourth resistor and the second switch tube;
one end of the third resistor receives the power supply voltage output by the pull-down power supply unit;
the other end of the third resistor is connected with the input end of the second switching tube, and the connection point is used as the output end of the pull-down control unit;
the output end of the second switching tube is grounded;
the second switch tube control end receives a shutdown/fault signal; when the switching power supply has an output abnormal fault, the shutdown/fault signal controls the second switching tube to be switched off;
the fourth resistor is arranged between the control end and the output end of the second switch tube.
4. The protection circuit of the switching power supply according to claim 1, wherein the pull-down control unit comprises: a fifth resistor, a sixth resistor and a comparator;
the output end of the comparator is used as the output end of the pull-down control unit;
a positive input end of the comparator is connected with one end of the fifth resistor and one end of the sixth resistor;
the other end of the fifth resistor receives the power supply voltage output by the pull-down power supply unit, and the other end of the sixth resistor is grounded;
the negative input end of the comparator receives a shutdown/fault signal; when the switching power supply has output abnormal faults, the shutdown/fault signal enables the comparator to output a conduction control signal.
5. The protection circuit of a switching power supply according to claim 3 or 4, wherein the shutdown/fault signal is derived from: and the power-off state pin of the control chip or the power-off state detection circuit of the switching power supply.
6. The protection circuit of any one of claims 1 to 4, wherein the pull-down power supply unit is configured to take power from an auxiliary winding of a switching transformer in the switching power supply.
7. The protection circuit of claim 6, wherein the pull-down power supply unit and the power supply pin of the control chip are powered from the same auxiliary winding.
8. The protection circuit of the switching power supply according to claim 7, wherein the pull-down power supply unit comprises: a diode and a capacitor;
the anode of the diode receives the power supply voltage of the auxiliary winding;
the cathode of the diode is grounded through the capacitor;
and the cathode of the diode provides a power supply voltage for the pull-down control unit.
9. The protection circuit of claim 6, wherein a voltage stabilizing circuit is further disposed between the pull-down power supply unit and the auxiliary winding.
10. A switching power supply, comprising: a main circuit, a control chip, a detection circuit, and a protection circuit of the switching power supply according to any one of claims 1 to 9; wherein:
the detection circuit is used for detecting the voltage and/or the current of the input end and/or the output end of the main circuit and outputting the voltage and/or the current to the control chip;
the control chip is used for realizing control and protection of the main circuit;
the protection circuit is used for pulling down the voltage of the power supply pin of the control chip to the ground when the switching power supply has output abnormal faults.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111470200.XA CN113991611B (en) | 2021-12-03 | 2021-12-03 | Switch power supply and protection circuit thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111470200.XA CN113991611B (en) | 2021-12-03 | 2021-12-03 | Switch power supply and protection circuit thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113991611A true CN113991611A (en) | 2022-01-28 |
| CN113991611B CN113991611B (en) | 2024-04-12 |
Family
ID=79733218
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111470200.XA Active CN113991611B (en) | 2021-12-03 | 2021-12-03 | Switch power supply and protection circuit thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113991611B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116406053A (en) * | 2023-06-08 | 2023-07-07 | 广东东菱电源科技有限公司 | Non-isolated topology afterglow removing circuit |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101257258A (en) * | 2007-02-28 | 2008-09-03 | 群康科技(深圳)有限公司 | Switch power circuit |
| CN101847934A (en) * | 2010-05-07 | 2010-09-29 | Bcd半导体制造有限公司 | A kind of Switching Power Supply |
| CN105610314A (en) * | 2016-02-24 | 2016-05-25 | 广州金升阳科技有限公司 | Input undervoltage protection circuit and method |
| JP2016116298A (en) * | 2014-12-12 | 2016-06-23 | 富士通株式会社 | Power supply unit, power supply circuit and method for controlling power supply circuit |
| CN214958665U (en) * | 2021-05-17 | 2021-11-30 | 成都信息工程大学 | Hiccup protection circuit, power chip |
-
2021
- 2021-12-03 CN CN202111470200.XA patent/CN113991611B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101257258A (en) * | 2007-02-28 | 2008-09-03 | 群康科技(深圳)有限公司 | Switch power circuit |
| CN101847934A (en) * | 2010-05-07 | 2010-09-29 | Bcd半导体制造有限公司 | A kind of Switching Power Supply |
| JP2016116298A (en) * | 2014-12-12 | 2016-06-23 | 富士通株式会社 | Power supply unit, power supply circuit and method for controlling power supply circuit |
| CN105610314A (en) * | 2016-02-24 | 2016-05-25 | 广州金升阳科技有限公司 | Input undervoltage protection circuit and method |
| CN214958665U (en) * | 2021-05-17 | 2021-11-30 | 成都信息工程大学 | Hiccup protection circuit, power chip |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116406053A (en) * | 2023-06-08 | 2023-07-07 | 广东东菱电源科技有限公司 | Non-isolated topology afterglow removing circuit |
| CN116406053B (en) * | 2023-06-08 | 2023-08-25 | 广东东菱电源科技有限公司 | Non-isolated topology afterglow removing circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113991611B (en) | 2024-04-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10090770B2 (en) | Isolated power converter with output voltage protection | |
| EP3258586B1 (en) | Power converter with load switch fault protection | |
| US9667055B2 (en) | Over-voltage protection apparatus and method of operating the same | |
| CN111697809B (en) | Switching power supply and control method thereof | |
| CN105529914B (en) | High-voltage starting circuit | |
| JP4752166B2 (en) | Switching power supply with storage capacitance and power regulation mechanism | |
| CN107947557B (en) | Soft start circuit for resisting overvoltage and undervoltage surges | |
| CN113991611B (en) | Switch power supply and protection circuit thereof | |
| CN104184331A (en) | Flyback switching power supply | |
| CN212163157U (en) | Driving circuit of startup input surge current prevention relay | |
| CN205490127U (en) | High -voltage startup circuit | |
| CN210350768U (en) | Protective circuit | |
| CN215817490U (en) | Output short-circuit protection circuit and switching power supply system | |
| CN107332435B (en) | Power supply circuit of pulse width modulation chip and switching power supply | |
| CN216390802U (en) | Switching power supply circuit of ammeter | |
| CN213782946U (en) | Charging circuit and uninterruptible power supply comprising same | |
| CN110492442B (en) | ACDC switching power supply protection circuit and protection method | |
| US6577485B2 (en) | Ultra-wide input range power supply for circuit protection devices | |
| CN219322275U (en) | Power supply circuit, auxiliary power supply and electronic equipment | |
| CN111697807B (en) | Switching power supply circuit and converter | |
| CN111384844A (en) | Power supply circuit for inhibiting instant starting-up impact current | |
| CN217824233U (en) | Voltage protection circuit and electric equipment | |
| CN110798056A (en) | Power supply circuit | |
| JP2020025434A (en) | Power supply circuit | |
| CN217522734U (en) | Starting circuit, power supply circuit and electronic equipment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |