CN110011279A - A kind of protective circuit of switch power source and Switching Power Supply Preservation tactics - Google Patents
A kind of protective circuit of switch power source and Switching Power Supply Preservation tactics Download PDFInfo
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- CN110011279A CN110011279A CN201910204720.2A CN201910204720A CN110011279A CN 110011279 A CN110011279 A CN 110011279A CN 201910204720 A CN201910204720 A CN 201910204720A CN 110011279 A CN110011279 A CN 110011279A
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- power supply
- switching power
- resistor
- switching
- mos transistors
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Classifications
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- 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
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
Abstract
A kind of protective circuit of switch power source and Switching Power Supply Preservation tactics that the embodiment of the present invention proposes; the bypass MOS transistors for being grounded the start-up resistor of Switching Power Supply when protective circuit of switch power source includes closure; in order to guarantee before bypass MOS transistors are closed; Switching Power Supply can establish output, and protective circuit of switch power source is additionally provided with the reference voltage time delay module for delay.It establishes and exports in Switching Power Supply, and after bypass MOS transistors closure, start-up resistor ground connection controls the supply voltage supplying power for input end of chip no longer for Switching Power Supply, and the supply voltage input terminal of the chip of Switching Power Supply control at this time is powered only by switching mode power supply transformer.When Switching Power Supply output short-circuit, switching mode power supply transformer can stop the supply voltage supplying power for input end that chip is controlled for Switching Power Supply immediately, this power supply for allowing for Switching Power Supply control chip can be cut off rapidly, the power supply for avoiding Switching Power Supply control chip delays to cut off, the caused working time under abnormal short-circuit condition is too long, the excessive problem of device loss.
Description
Technical field
The present embodiments relate to circuit protection technical fields, and in particular to a kind of protective circuit of switch power source and switch electricity
Source protection strategy.
Background technique
With the fast development of science and technology, various electronic products increasingly come into people's lives, and electronic product is once another
The secondary life for changing us, the clothing, food, lodging and transportion -- basic necessities of life of people increasingly be unable to do without electronic product, these we be all familiar with cannot be again
Known mobile phone, television set, computer, washing machine, air-conditioning, automobile etc. electronic product all be unable to do without the support of accessory power supply, and
Switching Power Supply is even more to occupy the overwhelming majority in accessory power supply, if Switching Power Supply goes wrong, then the function of entire product will go out
It now paralyses, influences very big.So a good Switching Power Supply is most basic condition to an electronic product.
Switching Power Supply plays most important as an auxiliary system very important in electronic product in electronic product
Effect.
Now due to there are certain fluctuations for network voltage, some high-power electric appliances are especially put into suddenly, such as electronic
Machine starting, starting of air conditioner, possible moment drag down attachment network voltage, at this time at low voltage, the input condition of Switching Power Supply
Challenge will be present, it is possible to will be unable to start, entire electronic product is caused to be unable to run, so in order to guarantee Switching Power Supply low
Can normally it start in the case of pressure, Switching Power Supply needs to have " Width funtion input function ".
The output of Switching Power Supply is often used on connecting terminal, and maloperation can inevitably occur for operator, is caused defeated
It is short-circuit out, in order to guarantee Switching Power Supply when short circuit occurs can timely interrupt output, guarantee that itself device is not damaged, also protect
Operator does not come to harm, and Switching Power Supply needs to have " output short circuit protection function ".
But in the design of Switching Power Supply, " Width funtion input function " and " output short circuit protection function " be one very
Contradictory two parameters.It should guarantee work normally in very low input voltage lower switch power supply, this requires very low
Input condition lower switch power supply control chip can obtain enough operating currents (referred to as " low voltage starting characteristic "), and it is more big more
It is good；However, certainly, being also included under maximum input voltage and opening to guarantee that Switching Power Supply has " output short circuit protection function "
Short circuit occurs for the output of powered-down source, and Switching Power Supply also can be carried out power supply automatic protection, interrupt output, then specifically, Switching Power Supply
Output short-circuit needs the work of the chip of interrupt switch power-supply system control immediately once occurring, and interrupts power supply output, still, this
Control chip operation electric current is smaller, easier interruption, also easier carry out short-circuit protection, this is under high input voltage to short circuit
Protect particularly important (referred to as " high voltage short circuit protection ").So far, it is clear that " low voltage starting characteristic " and " high voltage short circuit protection "
To the operating current of Switching Power Supply control chip require obviously to have moved towards two it is extreme, one is wanted as big as possible, and one will to the greatest extent can
Can be small, this is unfavorable to the design of Switching Power Supply.
In Switching Power Supply design, power supply system passes through access switch electricity after start-up resistor current limliting from Switching Power Supply input
Source controls the supply voltage input terminal of chip, gives Switching Power Supply control chip to provide initialization supply voltage, designer is in order to protect
Card can control chip power supply in the case where inputting low-voltage to Switching Power Supply, and often the starting current of Switching Power Supply is arranged
It is larger, start-up resistor is generally all smaller, but which results in when high input voltage, the power supply electricity of Switching Power Supply
Existing " surplus " is flowed out, so that the power supply of Switching Power Supply control chip delays to cut off in Switching Power Supply output short-circuit, is caused
Switching Power Supply working time under abnormal short-circuit condition is too long, and device loss is excessive, and device temperature rise is got higher.
Summary of the invention
When short circuit occurs in order to solve Switching Power Supply, cutting and the excessively high technical problem of device temperature of delaying of powering,
The embodiment of the invention provides a kind of protective circuit of switch power source and Switching Power Supply Preservation tactics.
In view of this, in a first aspect, the embodiment of the present invention provides a kind of protective circuit of switch power source, applied to switch electricity
Source, the Switching Power Supply include Switching Power Supply control chip, start-up resistor and switching mode power supply transformer, the Switching Power Supply control
The supply voltage input terminal of chip connects with a winding output end of the start-up resistor and the switching mode power supply transformer respectively
It connects, the protective circuit of switch power source includes:
Reference voltage time delay module and bypass MOS transistors；
The reference voltage output end of the input terminal of the reference voltage time delay module and Switching Power Supply control chip connects
It connects, for being delayed；
The control terminal of the bypass MOS transistors is connect with the reference voltage time delay module output end, passes through the benchmark electricity
Time delay module is pressed to provide control voltage；
The bypass MOS transistors also respectively with the start-up resistor and connect, bypass MOS transistors closure makes the starting
Resistance be connected to.
Optionally, the reference voltage time delay module includes:
First resistor, first capacitor and first diode；
One end of the first resistor is connect with the reference voltage output end, and the other end distinguishes the first diode
Anode is connected with one end of first capacitor；
The cathode of the first diode is connect with the input terminal of the charge-discharge modules；
The other end of the first capacitor is grounded.
Optionally, the protective circuit of switch power source further include: charge-discharge modules；
The input terminal of the charge-discharge modules is connect with the reference voltage time delay module output end, input terminal and the side
The control terminal of road metal-oxide-semiconductor connects；
The charge-discharge modules are charged by the reference voltage time delay module, and are discharged to the bypass MOS transistors.
Optionally, the charge-discharge modules include:
Electrolytic capacitor and second resistance；
The anode of the electrolytic capacitor is connect with the reference voltage time delay module, cathode ground connection；
The second resistance is in parallel with the electrolytic capacitor.
Optionally, the protective circuit of switch power source further include:
Input terminal is connect with the reference voltage time delay module, and output end is connect with the charge-discharge modules input terminal, is used
In the Current amplifier module for the charging current for increasing the charge-discharge modules.
Optionally, the Current amplifier module includes:
NPN type triode, PNP type triode and 3rd resistor；
The base stage of the NPN type triode is connect with the reference voltage time delay module, emitter ground connection, collector and institute
State the base stage connection of positive-negative-positive triode；
The collector of the positive-negative-positive triode is connect with one end of the 3rd resistor, emitter and triode power supply electricity
Source connection；
The other end of the 3rd resistor is connect with the charge-discharge modules.
Optionally, the bypass MOS transistors are N-channel mos field-effect tube；
The source electrodes of the bypass MOS transistors is grounded, and grid connect with the charge-discharge modules, drain and the start-up resistor and
The connection of field-effect tube power supply.
Second aspect, the embodiment of the present invention also provide a kind of Switching Power Supply Preservation tactics, comprising:
When Switching Power Supply starts, power supply system passes through the supply voltage input terminal that start-up resistor is that Switching Power Supply controls chip
Power supply；
The reference voltage of the reference voltage output end output of Switching Power Supply control chip is delayed mould by reference voltage
Block, delay threshold time；
In threshold time, Switching Power Supply establishes output, and switching mode power supply transformer winding is that the Switching Power Supply controls chip
Supply voltage supplying power for input end；
After threshold time, reference voltage time delay module is that the control terminal of bypass MOS transistors is powered；
When meeting the starting voltage of bypass MOS transistors, the connection of the start-up resistor and ground is connected in the bypass MOS transistors,
The start-up resistor is no longer the power supply supplying power for input end of the Switching Power Supply control chip；
When the Switching Power Supply output short-circuit, the switching mode power supply transformer winding stops being that the Switching Power Supply controls
The supply voltage supplying power for input end of chip, the Switching Power Supply control chip stop working.
Optionally, the Switching Power Supply Preservation tactics further include:
After Switching Power Supply control chip stops working, the charge and discharge mould that is connect with the control terminal of the bypass MOS transistors
BOB(beginning of block) electric discharge controls the bypass MOS transistors and continues that the connection of the start-up resistor and ground is connected, until the charge-discharge modules
Voltage be lower than the bypass MOS transistors starting voltage.
Compared with prior art, a kind of protective circuit of switch power source that the embodiment of the present invention proposes is applied to Switching Power Supply, packet
The bypass MOS transistors for being grounded the start-up resistor of Switching Power Supply when including closure, in order to guarantee before bypass MOS transistors are closed, switch electricity
Source can establish output, and protective circuit of switch power source is additionally provided with the reference voltage time delay module for delay.It is built in Switching Power Supply
Vertical output, and after bypass MOS transistors closure, start-up resistor ground connection controls the supply voltage input terminal of chip no longer for Switching Power Supply
The supply voltage input terminal of power supply, the chip of Switching Power Supply control at this time is powered only by switching mode power supply transformer.When switch electricity
When the output short-circuit of source, switching mode power supply transformer can stop the supply voltage supplying power for input end that chip is controlled for Switching Power Supply immediately,
This power supply for allowing for Switching Power Supply control chip can be cut off rapidly, and the power supply for avoiding Switching Power Supply control chip is slow
It cannot cut off, the caused working time under abnormal short-circuit condition is too long, the excessive problem of device loss.
Detailed description of the invention
In order to illustrate the technical solution of the embodiments of the present invention more clearly, below will be in embodiment or description of the prior art
Required attached drawing is briefly described, it should be apparent that, the accompanying drawings in the following description is only some realities of the invention
Example is applied, it for those of ordinary skill in the art, without any creative labor, can also be attached according to these
Figure obtains other attached drawings.
Fig. 1 is a kind of protective circuit of switch power source block diagram that the embodiment of the present invention one provides；
Fig. 2 is a kind of protective circuit of switch power source block diagram provided by Embodiment 2 of the present invention；
Fig. 3 is a kind of protective circuit of switch power source block diagram that the embodiment of the present invention three provides；
Fig. 4 is a kind of circuit diagram of protective circuit of switch power source provided in an embodiment of the present invention.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiments of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill people
Member's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
Important component of the Switching Power Supply as electronic product, generally includes:
Switching Power Supply controls chip, is the core component of Switching Power Supply, other devices for control switch power supply；
Start-up resistor, for Switching Power Supply control chip to be connect with power supply system, to input switch power supply control chip
Electric current carry out current limliting；With
Switching mode power supply transformer is used for voltage transformation；
Switching Power Supply control the supply voltage input terminal (VCC) of chip respectively with start-up resistor and switching mode power supply transformer
One winding output end connection.
In Switching Power Supply starting, power supply system passes through access switch electricity after start-up resistor current limliting from Switching Power Supply input
Source controls the supply voltage input terminal of chip, provides initialization supply voltage to Switching Power Supply control chip, in design, in order to
Guarantee " the low-voltage starting characteristic " of Switching Power Supply, the resistance value of start-up resistor is usually smaller.
Normally start in Switching Power Supply, and after establishing output, the supply voltage input terminal that Switching Power Supply controls chip is main
By switching mode power supply transformer winding power, no longer fully relies on and obtain electric current from start-up resistor.
When Switching Power Supply output short-circuit, the winding of switching mode power supply transformer can not be in normal output voltage, no longer to open
The supply voltage supplying power for input end of power supply control chip is closed, switching power source device is burnt out in order to prevent at this time, needs to cut off power supply
System and Switching Power Supply control chip supply voltage input terminal connection, and if power supply system provides high voltage at this time, by
Electric current " surplus " smaller in start-up resistor resistance value, being flowed through in start-up resistor, it will lead to the power supply of Switching Power Supply control chip
It delays to cut off, so that " high voltage short circuit protection " is undesirable.
In order to make Switching Power Supply be provided simultaneously with " low voltage starting characteristic " and " high voltage short circuit protection ", the present invention provides one kind
Protective circuit of switch power source applied to Switching Power Supply.
Embodiment one
Fig. 1 is a kind of protective circuit of switch power source schematic diagram provided in an embodiment of the present invention, referring to Fig.1, the Switching Power Supply
Protect circuit, comprising:
Reference voltage time delay module and bypass MOS transistors；
The reference voltage output end of the input terminal of the reference voltage time delay module and Switching Power Supply control chip
(VREF) it connects, for being delayed；
The control terminal of the bypass MOS transistors is connect with the reference voltage time delay module output end, passes through the charge and discharge
Module provides control voltage；
The bypass MOS transistors also respectively with the start-up resistor and connect, bypass MOS transistors closure makes the starting
Resistance be connected to.
Specifically, in the embodiment of the present application, the effect of reference voltage time delay module delay is to guarantee to close in bypass MOS transistors
Before conjunction, Switching Power Supply can establish output, because Switching Power Supply can not establish output at once in Switching Power Supply starting, if
, may be when the control terminal of bypass MOS transistors reach starting voltage if there is no reference voltage time delay module, Switching Power Supply is not yet
Output is established, this results in switching mode power supply transformer that can not control chip power supply for Switching Power Supply, and Switching Power Supply controls chip only
It can be powered by start-up resistor, and at this time since bypass MOS transistors control terminal has reached starting voltage, so bypass MOS transistors can close
Conjunction is grounded start-up resistor, so that start-up resistor can not control chip power supply also for Switching Power Supply, so as to cause the power supply that opens the light
Control chip is not powered, and can not be worked.
A kind of protective circuit of switch power source applied to Switching Power Supply that the embodiment of the present invention proposes, including will be opened when closure
The bypass MOS transistors of the start-up resistor ground connection in powered-down source, in order to guarantee before bypass MOS transistors are closed, Switching Power Supply can be established defeated
Out, protective circuit of switch power source is additionally provided with the reference voltage time delay module for delay.It establishes and exports in Switching Power Supply, and bypass
After metal-oxide-semiconductor closure, start-up resistor ground connection no longer controls the supply voltage supplying power for input end of chip for Switching Power Supply, switchs at this time
The supply voltage input terminal of power supply control chip is powered only by switching mode power supply transformer.When Switching Power Supply output short-circuit,
Switching mode power supply transformer can stop the supply voltage supplying power for input end that chip is controlled for Switching Power Supply immediately, this allows for switch electricity
The power supply of source control chip can be cut off rapidly, and the power supply for avoiding Switching Power Supply control chip delays to cut off, and be caused
The working time under abnormal short-circuit condition it is too long, the excessive problem of device loss solves " low voltage starting characteristic " and " high pressure
This contradiction of short-circuit protection ", so that the two characteristics can be guaranteed.
Embodiment two
Fig. 2 is a kind of protective circuit of switch power source schematic diagram provided in an embodiment of the present invention, referring to Fig. 2, the Switching Power Supply
Protect circuit, comprising:
Reference voltage time delay module, charge-discharge modules and bypass MOS transistors；
The reference voltage output end of the input terminal of the reference voltage time delay module and Switching Power Supply control chip
(VREF) it connects, for being delayed；
The input terminal of the charge-discharge modules is connect with the reference voltage time delay module output end, passes through the benchmark electricity
Pressure time delay module charges；
The control terminal of the bypass MOS transistors is connect with the charge-discharge modules output end, is mentioned by the charge-discharge modules
For controlling voltage；
The bypass MOS transistors also respectively with the start-up resistor and connect, bypass MOS transistors closure makes the starting
Resistance be connected to.
Due to Switching Power Supply short circuit, it will usually cause the device of Switching Power Supply to heat up, if when temperature is not fallen, it is split
Powered-down source is restarted, and biggish damage can be generated to device, so that the service life of device shortens.It is asked to solve this
Topic, the embodiment of the present application increase charge-discharge modules in protective circuit of switch power source, and the effect of charge-discharge modules is for side
The control terminal of road metal-oxide-semiconductor provides starting voltage, and guarantees to pass through within a period of time that Switching Power Supply controls that chip stops working
Discharging function remains closed bypass MOS transistors, to make Switching Power Supply control chip rest a period of time, makes entire Switching Power Supply
Carry out radiating and cooling.
The protective circuit of switch power source that the embodiment of the present invention proposes, when Switching Power Supply normally starts, Switching Power Supply is established
After output, switching mode power supply transformer can control the supply voltage supplying power for input end of chip for Switching Power Supply, when meeting bypass MOS transistors
Starting voltage when, bypass MOS transistors closure, start-up resistor be connected to, no longer for Switching Power Supply control chip supply voltage
Supplying power for input end, the chip of Switching Power Supply control at this time is powered only by switching mode power supply transformer, if Switching Power Supply output short-circuit,
Then switching mode power supply transformer can stop controlling chip power supply for Switching Power Supply at once, and at this time since charge-discharge modules have electric discharge
Function ensure that bypass MOS transistors still remain closed whithin a period of time, to make start-up resistor that can not be during this period of time
Switching Power Supply controls chip power supply, causes Switching Power Supply control chip that can not restart can only rest during this period of time, and opens
Powered-down source can make device radiate within this section of time of having a rest, avoid that device temperature is excessively high, and caused device is easy aging,
The problem of shortening to service life, while also solving " low voltage starting characteristic " and " high voltage short circuit protection " this contradiction, make
Obtaining the two characteristics can be guaranteed.
Embodiment three
Fig. 3 is a kind of protective circuit of switch power source schematic diagram provided in an embodiment of the present invention, referring to Fig. 3, the Switching Power Supply
Protect circuit, comprising:
Reference voltage time delay module, charge-discharge modules, Current amplifier module and bypass MOS transistors；
The reference voltage output end of the input terminal of the reference voltage time delay module and Switching Power Supply control chip
(VREF) it connects, for being delayed；
The input terminal of the Current amplifier module is connect with the reference voltage time delay module, output end and the charge and discharge
Module input connection, the electric current for exporting reference voltage time delay module increase, that is, increase filling for the charge-discharge modules
Electric current, to accelerate the charging rate of charge-discharge modules；
The control terminal of the bypass MOS transistors is connect with the charge-discharge modules output end, is mentioned by the charge-discharge modules
For controlling voltage；
The bypass MOS transistors also respectively with the start-up resistor and connect, bypass MOS transistors closure makes the starting
Resistance be connected to.
A kind of protective circuit of switch power source provided by the embodiments of the present application, when Switching Power Supply normally starts, Switching Power Supply
After establishing output, switching mode power supply transformer can control the supply voltage supplying power for input end of chip for Switching Power Supply, when charge and discharge mould
When the voltage of block meets the starting voltage of bypass MOS transistors, bypass MOS transistors closure, start-up resistor is connected to ground, be no longer switch it is electric
Source controls the supply voltage supplying power for input end of chip, and the chip of Switching Power Supply control at this time only passes through switching mode power supply transformer at this moment
Power supply, if Switching Power Supply output short-circuit, switching mode power supply transformer can stop controlling chip power supply for Switching Power Supply at once, and this
When due to charge-discharge modules have discharging function, ensure that bypass MOS transistors still remain closed whithin a period of time, to make to start
Resistance does not also control chip power supply during this period of time for Switching Power Supply, so this guarantees work as Switching Power Supply output short-circuit
When, Switching Power Supply control chip can stop working at once, and not work whithin a period of time, avoid Switching Power Supply control core
The power supply of piece delays to cut off, and the caused working time under abnormal short-circuit condition is too long, and device loss is excessive, also by
So that device is radiated in this idle a period of time, avoids the excessively high problem of device temperature rise, and the reference voltage being arranged is delayed
Circuit ensure that before bypass MOS transistors closure, Switching Power Supply completes the foundation of output, and the Current amplifier module being arranged will be used for
The electric current that reference voltage time delay module is exported increases, that is, increases the charging current of the charge-discharge modules, to accelerate charge and discharge
The charging rate of electric module.
One specific example:
As shown in figure 4, " P " network is Switching Power Supply input voltage, and it is " N " network with reference to ground, R108 is start-up resistor,
R108 is powered by the VCC that diode D32 controls chip to Switching Power Supply；
Reference voltage time delay module may include:
First resistor R171, first capacitor C108 and first diode D31；
One end of the first resistor R171 is connect with reference voltage output end VREF, and the other end distinguishes the one or two pole
The anode of pipe D31 is connected with one end of first capacitor C108；
The cathode of the first diode D31 is connect with Current amplifier module；
The other end of the first capacitor C108 is grounded.
Current amplifier module may include:
NPN type triode Q7, PNP type triode Q5 and 3rd resistor R95；
The base stage of the NPN type triode Q7 is connect with the cathode of first diode D31 in reference voltage time delay module, hair
Emitter grounding, collector are connect by resistance R169 with the base stage of the positive-negative-positive Q5 triode；
The collector of the positive-negative-positive triode Q5 is connect with one end of the 3rd resistor R95, and emitter and triode supply
Power supply VCC connection, base stage are connect by resistance R170 with triode power supply VCC；
The other end of the 3rd resistor R95 is connect with the charge-discharge modules input terminal.
Charge-discharge modules include:
Electrolytic capacitor E17 and second resistance R94；
The anode of the electrolytic capacitor E17 is connect with the 3rd resistor R95 in Current amplifier module, cathode ground connection；
The second resistance R94 is in parallel with the electrolytic capacitor E17.
Bypass MOS transistors are N-channel mos field-effect tube Q4；
The source electrode of the bypass MOS transistors Q4 is grounded, and grid is connect with the anode of electrolytic capacitor E17 in charge-discharge modules, is leaked
Pole is connect with the start-up resistor R180 and field-effect tube power supply MOSVCC.
Protective circuit of switch power source provided by the invention is applied in Switching Power Supply, a kind of novel switch electricity is formed
Source, novel Switching Power Supply include: Switching Power Supply control chip, start-up resistor, switching mode power supply transformer and any of the above-described implementation
Protective circuit of switch power source described in example；
The supply voltage input terminal of Switching Power Supply control chip respectively with the start-up resistor and the Switching Power Supply
One winding output end of transformer connects；
The reference voltage output end of the input terminal of the protective circuit of switch power source and Switching Power Supply control chip connects
It connects, the input terminal of the protective circuit of switch power source is connect with the start-up resistor.
Novel switched power supply provided by the embodiments of the present application, by the way that the protective circuit of switch power source of this programme proposition is arranged,
It ensure that in Switching Power Supply short circuit, the power supply of Switching Power Supply control chip can be cut off at once, avoid Switching Power Supply control
The power supply of coremaking piece delays to cut off, and the caused working time under abnormal short-circuit condition is too long, and device loss is excessive, device
Temperature rise is got higher.And protective circuit of switch power source is when that can keep one section of discharge condition after Switching Power Supply controls powering down chips
Between, so that start-up resistor is kept ground connection, do not control chip power supply for Switching Power Supply, since the power supply of Switching Power Supply control chip disappears
It loses, Switching Power Supply control chip enters " rest " of a period of time, and Switching Power Supply control chip is the " big of entire Switching Power Supply
Brain ", this section " rest " of " brain " make other devices of Switching Power Supply that can not enter operating mode (also and then resting), device
Part because " rest " loss of entire Switching Power Supply is not further added by, and this period device radiating, device surface is comprehensive
Temperature is closed to reduce rapidly.It has passed through this section " rest " time (discharge time of protective circuit of switch power source), switching circuit protection
Circuit automatically exits from operating mode, bypass MOS transistors shutdown, due to the runback bit function of Switching Power Supply control chip, Switching Power Supply
A new wheel starting is initially entered, the power supply of Switching Power Supply control chip starts to restore, until reaching entry condition, if at this time
" short circuit " still has, then repeatedly above procedure, if " short circuit " releases at this time, Switching Power Supply enters normal mode of operation.
Protective circuit of switch power source by the way that this programme proposition is arranged in Switching Power Supply can be as far as possible by starting current
It improves, when meeting " low voltage starting characteristic ", while solving the problems, such as " high voltage short circuit protection ".
Specifically, protective circuit of switch power source provided in this embodiment is applied when in Switching Power Supply, corresponding control
Method, comprising: when Switching Power Supply starts, power supply system passes through the supply voltage input that start-up resistor is that Switching Power Supply controls chip
End power supply；
The reference voltage of the reference voltage output end output of Switching Power Supply control chip is delayed mould by reference voltage
Block, delay threshold time；
In threshold time, Switching Power Supply establishes output, and switching mode power supply transformer winding is that the Switching Power Supply controls chip
Supply voltage supplying power for input end；
After threshold time, reference voltage time delay module is charge-discharge modules charging；
When the voltage of the charge-discharge modules meets the starting voltage of bypass MOS transistors, described in the bypass MOS transistors conducting
The connection of start-up resistor and ground, the start-up resistor are no longer that the power supply input terminal of the Switching Power Supply control chip supplies
Electricity；
When the Switching Power Supply output short-circuit, the switching mode power supply transformer winding stops being that the Switching Power Supply controls
The supply voltage supplying power for input end of chip, the Switching Power Supply control chip stop working；
The charge-discharge modules electric discharge controls the bypass MOS transistors and continues that the connection of the start-up resistor and ground is connected, directly
It is lower than the starting voltage of the bypass MOS transistors to the voltage of the charge-discharge modules.
For the protective circuit of switch power source described in Fig. 4, when Switching Power Supply powers on, and switched power output mouth at this time
Normally, input voltage P passes through R180, and D32 powers to the VCC pin of Switching Power Supply control chip, and Q4 is in an off state at this time,
The reference voltage output pin VREF that Switching Power Supply controls chip is low level；When Switching Power Supply control chip voltage charging terminates
And after stablizing, the VREF that Switching Power Supply controls chip is high level (common is 5V), and by R171, D31, C108 is delayed
" T " processing, in T time, Q4 is still within off state, and Switching Power Supply establishes output, and so far, Switching Power Supply controls chip
VCC pin mainly by switching mode power supply transformer winding power, no longer fully relies on and obtains electric current from R180.After T time,
Charging starts on E17, and the upper voltage of E17 (will also continue to rise) after reaching the cut-in voltage of metal-oxide-semiconductor Q4, Q4 conducting, the upstream R180
The electric current crossed all walks the pole D-S of Q4, and start-up resistor R180 no longer powers to the VCC pin of Switching Power Supply control chip, switch
The VCC pin of power supply control chip relies solely on switching mode power supply transformer winding power.So far, Switching Power Supply normally started
Journey is completed.
When Switching Power Supply output short-circuit, the power supply of switching mode power supply transformer auxiliary winding disappears, and the electricity flowed through on R180
Stream is also bypassed by the pole D-S of Q4, and VCC does not have voltage supplementary loop, is declined rapidly, until being not sufficient to ensure that power supply chip works,
Cause power supply control chip " rest ", entire Switching Power Supply is in halted state.
Since capacitance characteristic determines, the upper voltage of E17 will not be mutated, and E17 and R94 form discharge loop, and the upper voltage of E17 passes through
The T1 time is gradually decrease to the cut-in voltage of Q4, and within the T1 time, the VCC pin of Switching Power Supply control chip cannot charge, and opens
It closes power supply control chip not work, resting state is lasting.After time " T1 ", unlatching electricity of the upper voltage of E17 lower than metal-oxide-semiconductor Q4
Pressure, Q4 shutdown, R180 start to power by the VCC pin that D32 controls chip to Switching Power Supply again, open into a new wheel
Dynamic process.
By " rest " of T1 time, device is not further added by loss during this period of time, and fever no longer further increases, device
Part persistently radiates, by controlling T1 time, i.e., the degree of controllable heat dissipation.
Switching Power Supply provided by the embodiments of the present application is guaranteed by the way that the protective circuit of switch power source of this programme proposition is arranged
In Switching Power Supply short circuit, the power supply of Switching Power Supply control chip can be cut off at once, avoid Switching Power Supply control core
The power supply of piece delays to cut off, and the caused working time under abnormal short-circuit condition is too long, and device loss is excessive, device temperature rise
It gets higher.And protective circuit of switch power source can keep discharge condition for a period of time after Switching Power Supply controls powering down chips, make
Start-up resistor keeps ground connection, does not control chip power supply for Switching Power Supply, since the power supply of Switching Power Supply control chip disappears, switch
Power supply control chip enters " rest " of a period of time, and Switching Power Supply control chip is " brain " of entire Switching Power Supply, " big
This section " rest " of brain " enter Switching Power Supply other devices can not operating mode (also and then resting), device because
" rest " is further added by the loss of entire Switching Power Supply not, and this period device radiating, device surface integrated temperature
It reduces rapidly.It has passed through this section " rest " time (discharge time of protective circuit of switch power source), switching circuit protects circuit certainly
It is dynamic to exit operating mode, bypass MOS transistors shutdown, due to the runback bit function of Switching Power Supply control chip, Switching Power Supply start into
Enter a new wheel starting, the power supply of Switching Power Supply control chip starts to restore, until reaching entry condition, if at this time " short circuit "
It still has, then repeatedly above procedure, if " short circuit " releases at this time, Switching Power Supply enters normal mode of operation.
Protective circuit of switch power source by the way that this programme proposition is arranged in Switching Power Supply can be as far as possible by starting current
It improves, when meeting " low voltage starting characteristic ", while solving the problems, such as " high voltage short circuit protection ".
It should be noted that, in this document, the terms "include", "comprise" or its any other variant are intended to non-row
His property includes, so that the process, method, article or the device that include a series of elements not only include those elements, and
And further include other elements that are not explicitly listed, or further include for this process, method, article or device institute it is intrinsic
Element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that including being somebody's turn to do
There is also other identical elements in the process, method of element, article or device.
It should be noted that, in this document, the relational terms of such as " first " and " second " or the like are used merely to one
A entity or operation with another entity or operate distinguish, without necessarily requiring or implying these entities or operation it
Between there are any actual relationship or orders.
Through the above description of the embodiments, those skilled in the art can be understood that each reality of the present invention
Applying method described in example can realize by means of software and necessary general hardware platform, naturally it is also possible to by hardware,
But the former is more preferably embodiment in many cases.Based on this understanding, technical solution of the present invention is substantially in other words
The part that contributes to existing technology can be embodied in the form of software products, which is stored in one
In a storage medium (such as ROM/RAM, magnetic disk, CD), including some instructions are used so that a terminal device (can be hand
Machine, computer, server, air conditioner or network equipment etc.) execute method or implementation described in each embodiment of the present invention
Method described in certain parts of example.
The above is only a preferred embodiment of the present invention, is not intended to limit the scope of the invention, all to utilize this hair
Equivalent structure or equivalent flow shift made by bright specification and accompanying drawing content is applied directly or indirectly in other relevant skills
Art field, is included within the scope of the present invention.
Claims (9)
1. a kind of protective circuit of switch power source is applied to Switching Power Supply, which is characterized in that the Switching Power Supply includes Switching Power Supply
Control chip, start-up resistor and switching mode power supply transformer, the supply voltage input terminal of the Switching Power Supply control chip respectively with
The start-up resistor is connected with a winding output end of the switching mode power supply transformer, the protective circuit of switch power source packet
It includes:
Reference voltage time delay module and bypass MOS transistors；
The input terminal of the reference voltage time delay module is connect with the reference voltage output end of Switching Power Supply control chip, is used
In delay；
The control terminal of the bypass MOS transistors is connect with the reference voltage time delay module output end, is prolonged by the reference voltage
When module provide control voltage；
The bypass MOS transistors also respectively with the start-up resistor and connect, bypass MOS transistors closure makes the start-up resistor
It is connected to ground.
2. protective circuit of switch power source according to claim 1, which is characterized in that the reference voltage time delay module packet
It includes:
First resistor, first capacitor and first diode；
One end of the first resistor is connect with the reference voltage output end, and the other end distinguishes the anode of the first diode
It is connected with one end of first capacitor；
The cathode of the first diode is connect with the input terminal of the charge-discharge modules；
The other end of the first capacitor is grounded.
3. protective circuit of switch power source according to claim 1, which is characterized in that the protective circuit of switch power source also wraps
It includes: charge-discharge modules；
The input terminal of the charge-discharge modules is connect with the reference voltage time delay module output end, input terminal and the bypass
The control terminal of metal-oxide-semiconductor connects；
The charge-discharge modules are charged by the reference voltage time delay module, and are discharged to the bypass MOS transistors.
4. protective circuit of switch power source according to claim 3, which is characterized in that the charge-discharge modules include:
Electrolytic capacitor and second resistance；
The anode of the electrolytic capacitor is connect with the reference voltage time delay module, cathode ground connection；
The second resistance is in parallel with the electrolytic capacitor.
5. protective circuit of switch power source according to claim 3, which is characterized in that the protective circuit of switch power source also wraps
It includes:
Input terminal is connect with the reference voltage time delay module, and output end is connect with the charge-discharge modules input terminal, for increasing
The Current amplifier module of the charging current of the big charge-discharge modules.
6. protective circuit of switch power source according to claim 5, which is characterized in that the Current amplifier module includes:
NPN type triode, PNP type triode and 3rd resistor；
The base stage of the NPN type triode is connect with the reference voltage time delay module, emitter ground connection, collector with it is described
The base stage of positive-negative-positive triode connects；
The collector of the positive-negative-positive triode is connect with one end of the 3rd resistor, and emitter and triode power supply connect
It connects；
The other end of the 3rd resistor is connect with the charge-discharge modules.
7. protective circuit of switch power source according to claim 1, which is characterized in that the bypass MOS transistors are N-channel mos
Field-effect tube；
The source electrode of the bypass MOS transistors is grounded, and grid is connect with the charge-discharge modules, and drain electrode is imitated with the start-up resistor and field
It should the connection of pipe power supply.
8. a kind of Switching Power Supply Preservation tactics characterized by comprising
When Switching Power Supply starts, power supply system passes through the supply voltage input terminal confession that start-up resistor is that Switching Power Supply controls chip
Electricity；
The reference voltage of the reference voltage output end output of the Switching Power Supply control chip is prolonged by reference voltage time delay module
When threshold time；
In threshold time, Switching Power Supply establishes output, and switching mode power supply transformer winding is the confession that the Switching Power Supply controls chip
Piezoelectric voltage supplying power for input end；
After threshold time, reference voltage time delay module is that the control terminal of bypass MOS transistors is powered；
When meeting the starting voltage of bypass MOS transistors, the connection of the start-up resistor and ground is connected in the bypass MOS transistors, described
Start-up resistor is no longer the power supply supplying power for input end of the Switching Power Supply control chip；
When the Switching Power Supply output short-circuit, the switching mode power supply transformer winding stops being that the Switching Power Supply controls chip
Supply voltage supplying power for input end, Switching Power Supply control chip stops working.
9. Switching Power Supply Preservation tactics according to claim 8, which is characterized in that the Switching Power Supply Preservation tactics also wrap
It includes:
After the Switching Power Supply control chip stops working, the charge-discharge modules connecting with the control terminal of the bypass MOS transistors are opened
Begin to discharge, controls the bypass MOS transistors and continue that the connection of the start-up resistor and ground is connected, until the electricity of the charge-discharge modules
Force down the starting voltage in the bypass MOS transistors.
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| CN201910204720.2A CN110011279B (en) | 2019-03-18 | 2019-03-18 | Switching power supply protection circuit and switching power supply protection method |
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| CN201910204720.2A CN110011279B (en) | 2019-03-18 | 2019-03-18 | Switching power supply protection circuit and switching power supply protection method |
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