CN106786395A - A kind of protection circuit and method - Google Patents
A kind of protection circuit and method Download PDFInfo
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- CN106786395A CN106786395A CN201611131821.4A CN201611131821A CN106786395A CN 106786395 A CN106786395 A CN 106786395A CN 201611131821 A CN201611131821 A CN 201611131821A CN 106786395 A CN106786395 A CN 106786395A
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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
- H02H7/122—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 for inverters, i.e. dc/ac converters
- H02H7/1227—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 for inverters, i.e. dc/ac converters responsive to abnormalities in the output circuit, e.g. short circuit
-
- 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
- H02H3/08—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 responsive to excess current
- H02H3/087—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 responsive to excess current for dc applications
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a kind of protection circuit, boost circuits, the direct circuit for being input to output that the parasitic diode that the boost circuits are provided with first switch is formed are applied to；The protection circuit includes：Over-current detection circuit, is configured to sample the first electric current for flowing through the first switch；And detect whether first electric current meets first condition；There is excessively stream in the output current that the first condition characterizes the boost circuits；First control circuit, is configured to, when first electric current meets the first condition, the first control signal be exported to second switch；Second switch, is configured to response first control signal, disconnects the direct circuit.The present invention also discloses a kind of guard method.
Description
Technical field
The present invention relates to boost circuits, more particularly to a kind of protection circuit and method.
Background technology
With the progress of electric circuit electronics technical technology, Switching Power Supply constantly develops to high power density, high efficiency, high reliability,
The defencive function of Switching Power Supply has become an important indicator of reliability.
Boost circuits as Switching Power Supply a kind of most basic topology, in can be applied to non-isolated product, power density
Can be made thin high with efficiency.But there is inherent shortcoming in boost circuits：There is one in boost circuits from being input to
The direct circuit of output, when the serious excessively stream of output end or when being short-circuited, the huge current flow that the direct circuit can be produced, and this
Active switching devices or passive device such as inductance that huge electric current will be damaged in boost circuits.
Therefore, it is current to the damage caused by boost circuits how to control the huge current flow produced by direct circuit
Problem demanding prompt solution.
The content of the invention
To solve existing technical problem, the embodiment of the present invention provides a kind of protection circuit and method.
What the technical scheme of the embodiment of the present invention was realized in：
A kind of protection circuit is the embodiment of the invention provides, boost circuits are applied to, the boost circuits are provided with logical
Cross the direct circuit for being input to output that the parasitic diode of first switch is formed；The protection circuit includes：
Over-current detection circuit, is configured to sample the first electric current for flowing through the first switch；And detection is described
Whether the first electric current meets first condition；There is excessively stream in the output current that the first condition characterizes the boost circuits；
First control circuit, is configured to when first electric current meets the first condition, to second switch output the
One control signal；
Second switch, is configured to response first control signal, disconnects the direct circuit.
The embodiment of the present invention additionally provides a kind of guard method, is applied to boost circuits, and the boost circuits are provided with
The direct circuit for being input to output formed by the parasitic diode of first switch, methods described is included：
The first electric current to flowing through the first switch is sampled；
Detect whether first electric current meets first condition；The first condition characterizes the output of the boost circuits
There is excessively stream in electric current；
When first electric current meets the first condition, controlled to the second switch output first of the protection circuit
Signal, to disconnect the direct circuit.
Protection circuit provided in an embodiment of the present invention and method, over-current detection circuit are opened flowing through the first of boost circuits
The first electric current for closing is sampled；And detect whether first electric current meets first condition；When first electric current meets institute
When stating first condition, first control circuit exports the first control signal to second switch；The second switch response described first
Control signal, disconnects the direct circuit, detects described by being used to the first electric current for flowing through the first switch
Whether the output current of boost circuits occurs excessively stream, and (this excessively stream is properly termed as the serious excessively stream of output end of the boost circuits
Or output short-circuit), and when the output current excessively stream of the boost circuits is detected, the direct circuit is disconnected, and so, can
To prevent damage of the output end of the boost circuits in serious excessively stream or output short-circuit to boost circuits, so that effectively
Protect boost circuits.
Brief description of the drawings
In accompanying drawing (it is not necessarily drawn to scale), similar reference phase described in different views
As part.Similar reference numerals with different letter suffix can represent the different examples of similar component.Accompanying drawing is with example
Unrestricted mode generally shows each embodiment discussed herein.
Fig. 1 is a kind of asynchronous boost electrical block diagrams in correlation technique；
Fig. 2 is a kind of synchronous boost electrical block diagrams in correlation technique；
Fig. 3 is the first the protection circuit structural representation of the embodiment of the present invention one；
Fig. 4 is the second protection circuit structural representation of the embodiment of the present invention 1；
Fig. 5 is the third protection circuit structural representation of the embodiment of the present invention one；
Fig. 6 is a kind of protection circuit structural representation of the embodiment of the present invention two；
Fig. 7 is another protection circuit structural representation of the embodiment of the present invention two；
Fig. 8 is the working timing figure of circuit shown in the Fig. 7 of the embodiment of the present invention two；
Fig. 9 is the third protection circuit structural representation of the embodiment of the present invention two；
Figure 10 is the 4th kind of protection circuit structural representation of the embodiment of the present invention 2；
Figure 11 is the over-current detection circuit structural representation of this embodiment of the present invention two；
Figure 12 is embodiment of the present invention guard method schematic flow sheet；
Figure 13 is using the simulation result figure of the circuit of the embodiment of the present invention.
Specific embodiment
At present, as shown in figure 1, the basic composition of one kind of boost circuits includes：Inductance L, MOSFET Q1, diode D1 and
Corresponding electric capacity.This boost circuits are properly termed as asynchronous (Non-sync) boost circuits.In this boost circuits, by
In the presence of diode D1, there is input overvoltage, input undervoltage, output overcurrent, the unusual condition of output short-circuit in boost circuits
When, input voltage can be directly output to output end by diode D1, that is, exist by leading directly to that inductance L, diode D1 are formed
Circuit, now output voltage be approximately equal to input voltage, it is impossible to complete switch off；And the power consumption of D1 is big, so the efficiency of circuit is simultaneously
It is not very high.
Based on the defect existing for the boost circuits shown in Fig. 1, the boost circuits shown in Fig. 2 are generated.Such as Fig. 2 institutes
Show, the boost circuits are included：Inductance L, MOSFET Q1, MOSFET Q2 and corresponding electric capacity.This boost circuits can claim
It is synchronization (Sync) boost circuits.The conducting resistance of this boost circuits MOSFET Q2 can be very small, causes the power consumption of Q2
Substantially reduce, the efficiency of whole boost circuits is greatly improved.
The application principle of the boost circuits shown in Fig. 1 and Fig. 2 is：MOSFET Q1 are turned on, and input voltage source (VIN) is to electricity
Sense L is charged, and when MOSFET Q1 shut-offs, MOSFET Q2 or D1 difference afterflow are simultaneously charged to output capacitance Cout, have reached liter
The purpose of pressure.
Wherein, when boost circuits reach stable state, input voltage meets with output voltage relation：VOUT=VIN/(1-
D), while input electric current is more than output current.
Wherein, VOUTStatement output voltage, i.e. output end VOUT voltages, VINInput voltage, i.e. input VIN voltage are represented,
D represents the dutycycle of switch periods.
For the boost circuits shown in Fig. 2, there is parasitic diode in MOSFET Q2, and this parasitic diode be can not
Eliminated by improving manufacture craft, so in the boost circuits, still in the presence of one from the straight-through electricity for being input to output
Road, i.e., the direct circuit for being formed by the parasitic diode between the source-drain electrode of inductance L, MOSFET Q2.
There is the serious excessively stream of output end in boost circuit starts or normal work, or directly output end vo ut is short
When road is to ground, the electric current that the direct circuit is produced is by the state in that can not limit until inductance L saturations (inductance) or active
Untill switching device burns out, in some instances it may even be possible to circuit can be caused on fire, boost circuits are caused to damage.That is, output end exists
Unnecessary destruction can be caused when the serious excessively stream of electric current or output short-circuit to boost circuits.
Based on this, in various embodiments of the present invention：For the parasitic diode institute shape for being provided with first switch
Into the direct circuit for being input to output boost circuits, the first electric current to flowing through boost circuit first switches adopts
Sample；Detect whether first electric current meets first condition；The first condition characterizes the output current hair of the boost circuits
Raw excessively stream；When first electric current meets the first condition, to second switch output the first control letter of the protection circuit
Number, to disconnect the direct circuit.
Only represent the element of diverse location not to the ginseng of element it should be noted that used herein first, second ...
Number or function are defined；Or different parameters is represented, but the size to parameter is not defined.
Embodiment one
The protection circuit that the present embodiment is provided, is applied to boost circuits, and the boost circuits are provided with first and open
What the parasitic diode of pass was formed is input to the direct circuit of output, as shown in figure 3, the circuit includes：Over-current detection circuit
31st, first control circuit 32 and second switch 33；Wherein,
The first electric current that the over-current detection circuit 31 pairs flows through the first switch is sampled；And detect described first
Whether electric current meets first condition；When first electric current meets the first condition, the first control circuit 32 is to
Two switches 33 export the first control signal；The second switch 33 responds first control signal, disconnects the direct circuit.
Here, the first condition characterizes the output current generation excessively stream of the boost circuits.
In embodiments of the present invention, what the parasitic diode that the boost circuits are provided with first switch was formed
It is input to the direct circuit of output.That is, the boost circuits in the embodiment of the present invention are synchronization boost circuits, as such as
Boost circuits shown in Fig. 2.Correspondingly, the first switch is the metal-oxide-semiconductor Q2 in circuit shown in Fig. 2.
In synchronous boost circuits, detect described by being used to the first electric current for flowing through the first switch
Whether the output current of boost circuits occurs excessively stream, and (this excessively stream is properly termed as the serious excessively stream of output end of the boost circuits
Or output short-circuit), and when the output current excessively stream of the boost circuits is detected, the direct circuit is disconnected, and so, can
To prevent damage of the output end of the boost circuits in serious excessively stream or output short-circuit to boost circuits, so that effectively
Protect boost circuits.
In embodiments of the present invention, the over-current detection circuit 31 is not increase the basis of the boost circuit power consumptions
On, first electric current is sampled, because the over-current detection circuit 31 does not increase boost circuits in the course of the work
Power consumption, so improve the voltage conversion efficiency of boost circuits.
Here, during practical application, can by way of the parallel equivalent resistance of the first switch two ends come to described
First electric current is sampled, and the purpose of the boost circuit power consumptions is not increased so as to reach.
In one embodiment, in the middle of the second switch 33 can be arranged on the boost circuit output stages and load,
That is, it is in series with the second switch 33 between the output stage and load.After first control signal is received, institute
State second switch 33 and respond first control signal, disconnect the connection between the boost circuit output ends and load.This
Sample, can realize that load is fully disconnected with boost circuit primes, that is to say, that the prime of boost circuits remain as one it is complete
Whole boost topologys, so as to protect load and boost circuits simultaneously.Meanwhile, the power consumption of boost circuits will not be increased, so that
Improve the voltage conversion efficiency of boost circuits.
Wherein, can know with reference to Fig. 2, the output stage refers to boost circuit output ends (VOUT)；Boost primes are
Refer to comprising inductance L, metal-oxide-semiconductor Q1, metal-oxide-semiconductor Q2 these devices circuit, the circuit can realize the boost conversion of DC voltage.
In one embodiment, the second switch 33 can also be serially connected in the input of the boost circuits.It is specific next
Say, in the circuit shown in Fig. 2, the second switch of being connected between input VIN and inductance L.Controlled when receiving described first
After signal processed, the second switch 33 responds first control signal, disconnects between the boost circuit input ends and inductance
Connection.
During practical application, the second switch 33 comprising P-channel metal-oxide-semiconductor FET (PMOS) or
NMOS, but the relative NMOS of the grid of PMOS level control is simple, therefore will phase to second switch conducting and the control for disconnecting
To fairly simple, so as to reduce circuit cost.
During practical application, in the boost circuit courses of work, the stability of boost circuital currents is should also ensure that.
Based on this, in one embodiment, as shown in figure 4, the protection circuit can also include：Second control circuit 34；Its
In,
During the boost circuits normal work, the second control circuit 34 can be made by the control mode of negative-feedback
The boost circuit output ends voltages keep constant.
Here, during practical application, the second control circuit 34 is by the 3rd switch (such as Fig. 2 to the boost circuits
Shown Q1) current sample, the current loop circuit of the boost circuits is controlled, so as to realize the stabilization of boost circuital currents
Property, i.e., the voltage of described boost circuit outputs stabilization.Meanwhile, the second control circuit 34 also limit the 3rd switch
Peak point current, it is achieved thereby that in the boost circuits inductive current peak value control.
When first electric current meets the first condition, the second control circuit 34 is exported to the first switch
Second control signal, and to the 3rd switch the 3rd control signal of output of the boost circuits, so that the boost circuits stop
Boosting modulation only is carried out to input voltage.
Wherein, the second control control signal is reverse with the phase of the 3rd control signal.
In other words, the second control circuit 34 closes the front stage circuits of the boost circuits, makes the boost
Circuit is closed.
From the above description, it will be seen that in embodiments of the present invention, the electric current to the first switch of boost circuits is adopted
Sample be used to judging output current whether excessively stream, and the current sample of the 3rd of boost circuits switch is used for current loop circuit
Control and the 3rd switch peak current limitation.
In one embodiment, as shown in figure 5, the protection circuit can also include：3rd control circuit 35；Wherein,
The 3rd control circuit 35 controls the testing result of over-current detection circuit output in real time to described first
Circuit 32 and second control circuit 34, to allow the first control circuit 32 and second control circuit 34 to know the boost
Whether the output current of circuit there is excessively stream.
Here, during practical application, when boost circuits are possible to that error condition can be in, such as described first switch is missed
During disconnection, now the testing result of the over-current detection circuit 31 is invalid, at this time, it may be necessary to be detected by output end voltage
Whether output end current there is excessively stream.So the 3rd control circuit 35 is received and enables signal；The enable signal is responded, will be described
The testing result of over-current detection circuit 31 is exported to the first control circuit 32 and second control circuit 34 in real time, to allow
State first control circuit 32 and second control circuit 34 knows whether the output current of the boost circuits occurs excessively stream.
Based on this, in one embodiment, the 3rd control circuit 35 is received and removes enable signal, is gone to enable described in response and is believed
Number, detect whether the output end voltage of the boost circuits meets second condition；The second condition characterizes the output end electricity
Force down input voltage in the boost circuits to preset value；And to the first control circuit 32 and second control circuit
34 output testing results；
Correspondingly, when the output end voltage of the boost circuits meets the second condition, the first control electricity
Road, the first control signal is exported to the second switch；It is when the output end voltage of the boost circuits meets the Article 2
During part, the second control circuit 34 exports the second control signal to the first switch, and to the 3rd of the boost circuits the
Switch the 3rd control signal of output.
Wherein, it is described to remove to enable signal for indicating to carry out over-current detection using the output voltage.
When the described 3rd control circuit 35 receives enable signal, the testing result of the over-current detection circuit 31 is illustrated
It is invalid, it is necessary to carry out over-current detection using output voltage.
Here, the preset value is configured as needed, for example for, it is assumed that parasitic two pole of power MOSFET
Tube voltage drop is in 0.5V-0.7V, so preset value can be set to 1V.
In one embodiment, after the prime and output stage of the boost circuits are closed, it is possible to achieve the boost electricity
Road and the soft start of the second switch.
Specifically, after the boost circuits are closed, the 3rd control circuit 35 determines the restarting boost electricity
The stand-by period on road；After the stand-by period reaches, the boost circuits and second switch are restarted；The over-current detection
Circuit 31 detects that the first electric current for flowing through the first switch is sampled in circuit restarting procedure；And detect described
Whether one electric current meets the first condition；When first electric current meets the first condition, the first control circuit
32 export first control signal to second switch 33, so that the second switch 33 stops restarting；Correspondingly, institute is worked as
When stating the first electric current and meeting the first condition, the second control circuit 34 is to first switch output the second control letter
Number, and the 3rd control signal is exported to the described 3rd switch, so that the boost circuits stop restarting.
In the restarting procedure of the boost circuits and second switch 33, when detecting the output current still
During generation excessively stream, boost circuits and second switch 33 can be allowed to stop restarting.Then after the new again stand-by period reaches, then
It is secondary to go to detect whether the output current still occurs excessively stream, when the over-current phenomenon avoidance for detecting the output current disappears,
Under the control of the 3rd control circuit 35, the boost circuits and second switch 33 can normal soft starts.This soft start side
Formula is properly termed as the soft start of " hiccup (hiccup) " pattern, using this soft starting mode, can substantially reduce boost circuits
And the power consumption of second switch.
During practical application, the stand-by period is the capacitance according to needed for soft start and the sampling electricity to the output end
Press to determine.
Embodiment two
The present embodiment is a concrete application example of circuit shown in Fig. 5.
In the present embodiment, as shown in fig. 6, boost circuits 61 include：Inductance L, metal-oxide-semiconductor Q1, metal-oxide-semiconductor Q2, input electricity
Hold Cin and output capacitor Cout1；
Over-current detection circuit (OC) 31, the electric current to flowing through metal-oxide-semiconductor Q2 is sampled, and judges whether excessively stream；
First control circuit 32 includes PMOS logic control circuits (PMOS Control)；
Second switch 33 includes PMOS Q3；
Second control circuit 34 includes：Resistance R1, resistance R2, error amplifier EA0, comparator Comp1, a SR
Latch SR1, pulse width modulation (PWM) logic control circuit (PWM Control) and phase inverter INV1.Resistance R1, resistance
R2, error amplifier EA0, comparator Comp1 and the first S/R latch SR1 form electric current loop negative feedback control circuit, come
Control the stability of boost circuital currents；
3rd control circuit 35 includes：SS logic control circuits (SS Control) and switch S3.
Wherein, metal-oxide-semiconductor Q1 and Q2 are N-channel metal oxide semiconductor field effect tube (NMOS).
For convenience, in the following description, by the negative of resistance R1, resistance R2 and error amplifier EA0
The node that input is formed referred to as FB；The output end node of boost circuits is VOUT, and load end node is VOUT_LOAD, by mistake
The output end of difference operation amplifier EA0 is referred to as SS_Ready.In the chips, these nodes are properly termed as the pin of chip.
PGATE, SS are the pin of chip.
The operation principle of the protection circuit shown in Fig. 6 is：
In the boost circuit courses of work, 31 pairs of electric currents for flowing through metal-oxide-semiconductor Q2 of the over-current detection circuit are sampled,
And over-current detection (obtaining detection signal Q2_OC) is carried out, and when there is excessively stream in the output current of the boost circuits, SS logics
Control circuit will switch S3 conductings, and so as to drag down the voltage of SS pins, now the normal phase input end of error amplifier EA0 connects
SS pins, rather than reference signal node VREF, so that error amplifier EA0 exports low level, and export extremely
PMOS logic control circuits, PMOS logic control circuits draw high the voltage of PGATE, and export to PMOS according to low level signal
The grid of Q3, so as to cause PMOS Q3 to turn off.Wherein, PMOS logic control circuits receive enable signal (EN_Q2) (high level
Signal) start working afterwards.
Meanwhile, the low level signal of error amplifier EA0 outputs so that metal-oxide-semiconductor Q1 and metal-oxide-semiconductor Q2 disconnects, so that
Stop being charged for electric capacity Cout1, i.e. boost circuits are stopped.
For first control circuit 32 (PMOS logic control circuits) and the 3rd control circuit 35, as shown in fig. 7, the first control
Circuit processed 32 includes：Second latch SR2, the second phase inverter INV2, switch S1, switch S2, Zener diode (zener
Diode) Z1, current source IA；
3rd control circuit 35 includes：Comparator Comp2, multi-channel gating device, the 3rd S/R latch SR3, delayer, switch
S3.Wherein, comparator Comp2 is hysteresis comparator.Comparator Comp2, multi-channel gating device, the 3rd S/R latch SR3, delayer
Composition SS logic control circuits.
With reference to Fig. 7, the operation principle of first control circuit 32 (PMOS logic control circuits) is：
During PMOS Q3 start, the signal ON switch that first control circuit 32 is exported using the second latch SR2
S1, the electric current (such as 60 μ A) that now current source IA is provided progressively drags down the voltage of PGATE pins up to being less than from PGATE ends
VOUT pin voltages.When the gate source voltage of PMOS Q3 is less than threshold voltage, PMOS Q3 are progressively turned on, and now one from boosting
Circuit to the current path for loading progressively is set up, and the output current of output end is slow to charge to output capacitance Cout1, simultaneously because
The progressively conducting of PMOS Q3, the voltage at VOUT_LOAD ends also slowly rises, so as to realize the soft start of load terminal voltage, it is to avoid
The generation of load end surge current.When PMOS Q3 gate source voltage clamper to the clamp voltage with Zener diode Z1 (such as
When 8V) identical, PMOS Q3 are fully on.
When over-current detection circuit 31 detects output current generation excessively stream, i.e., when the load overcurrent or defeated that generation is serious
When going out short circuit, the 3rd control circuit (SS logic control circuits) 35 can be by the voltage pull-down of SS pins, so that switch S2 connects
Logical, the voltage of PGATE pins is driven high, and causes PMOS Q3 to turn off, and load disconnects from the output end of boost circuits.
It should be noted that：During practical application, metal-oxide-semiconductor Q2 can be determined according to the peak power output of boost circuits
Corresponding first current threshold (being used for judging the whether serious excessively stream of output current or output short-circuit).
Be can be seen that in the chips from Fig. 6 and Fig. 7, be integrated with metal-oxide-semiconductor Q1, metal-oxide-semiconductor Q2, over-current detection circuit 31, first
Control circuit 32, the control circuit 35 of second control circuit 34 and the 3rd.And constitute the other devices of boost circuits 61, PMOS
Q3 is then not integrated on chip.
Can know in from the description above, the 3rd control circuit 35 notifies over-current detection result to give the second control electricity
Road 34, and second control circuit 34 notifies over-current detection result to give first control circuit 32.
When the serious load overcurrent of generation or output short-circuit persistently occur, boost electricity is started using hiccup pattern
Road and PMOS Q3, to reduce the power consumption of boost circuits and PMOS Q3.
Fig. 8 is the timing diagram of the circuit groundwork node shown in Fig. 7.The start-up course of hiccup pattern includes：
First stage, when be short-circuited (HS) when, the voltage of VOUT_LOAD points declines, and the electric current (IL) of inductance L is raised,
The current signal (Q2_OC) for flowing through metal-oxide-semiconductor Q2 of now over-current detection circuit detection is uprised, now the SS of the 3rd control circuit 35
Logic control circuit will switch SS conductings, so as to the voltage of SS pins be dragged down rapidly, so that the level of SS_READY becomes
Low, the low level of SS_READY causes the gate source voltage (V of POMS Q3GS_PMOS) no-voltage is risen to, ultimately result in PMOS Q3 passes
Disconnected, load disconnects from the output end of boost circuits, realizes the protection of load cut-off.Meanwhile, the voltage step-down of SS_READY makes
Obtain metal-oxide-semiconductor Q1 and Q2 to disconnect, boost circuits are stopped.
Second stage, after the protection of load cut-off starts, the SS logic control circuit time delays of the 3rd control circuit 35 set
After fixing time, switch S3 is disconnected, now electric capacity Css is electrically charged again so that the voltage of SS pins is raised, when SS voltage ratios FB electricity
When pressing high, the output of error amplifier EA0 is that the level of SS_READY is uprised, and the voltage of SS_READY is uprised so that MOS
Pipe Q1, metal-oxide-semiconductor Q2 and PMOS Q3 restart, and during boost circuits restart, inductive current (IL) can increase
Plus, if short circuit phenomenon is still present, the voltage of VOUT_LOAD points is still low pressure, over-current detection circuit output signal (Q2_
OC high level) is remained as, now the SS logic control circuits of the 3rd control circuit 35 can be again switched on switching S3, by SS pins
Voltage is dragged down rapidly, so that the voltage of SS_READY step-down again, the voltage step-down of SS_READY causes the grid of POMS Q3
Source voltage (VGS_PMOS) be again raised to zero, ultimately result in PMOS Q3 and stop conducting, load from the output end of boost circuits again
It is disconnected, the protection of load cut-off is realized again.Meanwhile, step-down causes metal-oxide-semiconductor Q1 and Q2 to the voltage of SS_READY again
Shutdown switch.If load short circuits are continued for, second stage can be repeated always.
Phase III, after second stage terminates, after the SS logic control circuit delay adjustmentses times of the 3rd control circuit 35,
Switch S3 is disconnected, now electric capacity Css is electrically charged again, and the voltage of SS pins is raised again, so that the level of SS_READY
Uprise, SS_READY high level causes that metal-oxide-semiconductor Q1, metal-oxide-semiconductor Q2 and PMOS Q3 restart, in the restarting of these devices
During, inductive current (IL) can increase, and when short circuit phenomenon disappears, the voltage of VOUT_LOAD points is raised, over-current detection electricity
Road output signal (Q2_OC) is low level, is finally completed metal-oxide-semiconductor Q1, the startup of metal-oxide-semiconductor Q2 and PMOS Q3, boost circuits
Switching function recover.
Wherein, the above-mentioned process that restarts is properly termed as soft start-up process, is an automatic process restarted.Entirely started
The time of Cheng Suoxu is properly termed as the hiccup time.And, from the above description, it will be seen that the duration of hiccup time is by FB's
The capacitance of voltage and Css is determined.
Here, for the SS logic control circuits of the 3rd control circuit 35, when boost circuits 61 are in error condition,
When such as metal-oxide-semiconductor Q2 is opened by wrong diagnosis, signal EN_Q2 zero setting, as low level signal are enabled, it can be understood as be one and go to enable
Signal, the SS logic control circuits of the 3rd control circuit 35 use output end voltage (VOUT) know whether output end current is sent out
Raw excessively stream, specifically, works as VOUTLess than input (VIN) voltage (VIN) and during more than preset value (such as 1V), it is believed that output end electricity
Stream there occurs excessively stream.Certainly, when it is high level to enable signal EN_Q2, the logic control circuit of the 3rd control circuit 35 is utilized
The over-current detection result of over-current detection circuit 31 knows whether output end current occurs excessively stream.
In powerful boost circuits application, such as the voltage of input (VIN) is far below output end (VOUT) voltage
When, PMOS Q3 have high current, i.e., with larger total grid electric charge (Qg), and high current (Qg) can reduce the shut-off of PMOS Q3
Speed, so may result in cut-off current much larger than setting value.Therefore during practical application, in specific applied environment, such as Fig. 9
It is shown, Schottky diode D1 to a PGATE end can be bridged from VIN ends, to accelerate the turn-off speed of PMOS Q3.
During practical application, it is also possible to which PMOS Q3 are arranged on into input, the guarantor to circuit is realized by disconnecting input
Shield.As shown in Figure 10, PMOS Q3 are serially connected between VIN ends and inductance L, so as to realize the disconnection of boost circuits input.
Wherein, the circuit shown in Figure 10 is used the 3rd control circuit and second control circuit and the electricity shown in Fig. 6 and 7
The work on road is identical, so corresponding operation principle is also identical, repeats no more here.
Circuit shown in Figure 10 with circuit shown in Fig. 6 and Fig. 7 except that：
First, because PMOS Q3 are serially connected in input, so needs concatenate one between ground and the drain electrode of PMOS Q3
Diode D2.So, when output current occurs excessively stream, PMOS Q3 are immediately opened, and can be now electricity using diode D2
Sense L afterflows, to ensure inductance L normal works.
Second, because the source electrode of PMOS Q3 is connected with input (VIN), so first control circuit 32 is also required to
It is connected with input (VIN).
Here, it is necessary to what is illustrated is：PMOS logic controls (PMOS Logic Control) bag in circuit shown in Figure 10
The corresponding device that circuit is controlled with door and the 3rd of the first control circuit 32 shown in Fig. 7 is contained.
Figure 11 shows the circuit composition of over-current detection circuit 31.As shown in figure 11, over-current detection circuit (OC) 31 includes：
Resistance R3, current source Iset, switch S4, switch S5 and comparator Comp3.
When metal-oxide-semiconductor Q2 is in the conduction state, switch S4 and switch S5 are turned on, and over-current detection circuit 31 is started working, when
IQ2*RQ2>Iset*R3When, comparator Comp3 output high level signals illustrate to there occurs excessively stream.Wherein, IQ2Expression flows through MOS passes
The electric current of Q2, RQ2Represent that MOS closes the conducting resistance of Q2, IsetRepresent the electric current that current source Iset is provided, R3Represent the electricity of resistance R3
Resistance.
It can be seen from fig. 11 that there is no any extra loss on the power transmission loop of boost circuits, so excessively stream
Detection circuit 31 is a kind of idle detection circuit.
Based on above-described embodiment protection circuit, the embodiment of the present invention additionally provides a kind of guard method, is applied to boost electricity
Road, the direct circuit for being input to output that the parasitic diode that the boost circuits are provided with first switch is formed, such as
Shown in Figure 12, the method is comprised the following steps：
Step 1201：The first electric current to flowing through the first switch is sampled；
Step 1202：Detect whether first electric current meets first condition；The first condition characterizes the boost electricity
There is excessively stream in the output current on road；
Step 1203：When first electric current meets the first condition, the second switch to the protection circuit is defeated
Go out the first control signal, to disconnect the direct circuit.
Here, in one embodiment, the disconnection direct circuit, including：
Disconnect the connection of the boost circuit output ends and load.
Here, during practical application, the disconnection direct circuit can also be the input for disconnecting the boost circuits.
In one embodiment, the method can also include：
When first electric current meets the first condition, to the first switch the second control signal of output, and to
3rd switch the 3rd control signal of output of the boost circuits, so that the boost circuits stop rising input voltage
Pressure modulation；Wherein,
The second control control signal is reverse with the phase of the 3rd control signal.
In one embodiment, the method can also include：
When enable signal is received, go to enable signal described in response, detect the output end voltage of the boost circuits
Whether second condition is met；The second condition sign output end voltage is less than the input voltage of the boost circuits extremely
Preset value；
When the output end voltage of the boost circuits meets the second condition, first is exported to the second switch
Control signal；The second control signal is exported to the first switch, and the 3rd control signal is exported to the described 3rd switch.
Wherein, it is described to remove to enable signal for indicating to carry out over-current detection using the output voltage.
During practical application, after boost circuits are closed, after reaching the stand-by period, the restarting boost circuits and the
Two switches；
Detect that the first electric current for flowing through the first switch is sampled in circuit restarting procedure；And detection institute
State whether the first electric current meets the first condition；
When first electric current meets the first condition, first control signal is exported to the second switch,
So that the second switch stops restarting；
When first electric current meets the first condition, to the first switch the second control signal of output, and to
3rd switch the 3rd control signal of output, so that the boost circuits stop restarting.
Meanwhile, in order to be better described using the technical scheme of the embodiment of the present invention, protection can be played to boost circuits
Effect, emulation experiment has been carried out using the circuit shown in Fig. 6 and Fig. 7.Experiment condition is：Caused using the resistance of 100m Ω
Boost circuits are short-circuited.
Figure 13 shows simulation result.When allowing boost circuits to be short-circuited using control logic, metal-oxide-semiconductor Q2 hairs are detected
The serious excessively stream of life, now protection circuit can disconnect PMOS Q3, and boost circuits are closed, to play protection boost circuits
Effect.After boost circuits are closed, the soft starting mode using hiccup pattern starts boost circuits and PMOS Q3, obtains
Simulation result as shown in fig. 13 that.Wherein, in fig. 13, from top to bottom, the curve in every width figure is represented respectively：Soft start-up process
Middle input VIN and output end VOUT_LOAD voltage curves, voltage (SS_READY voltages) curve of soft start, metal-oxide-semiconductor Q2 are tight
Traffic identifier curve, output end fault control curve, the current curve of inductance L are crossed again.From such results, it can be seen that boost is electric
Road is working properly, absolutely proves that boost circuits have obtained effectively protecting using after scheme provided in an embodiment of the present invention, tool
Body surface is present：After using scheme provided in an embodiment of the present invention to disconnect PMOS Q3, and boost circuits closed, boost
Circuit can realize soft start；Meanwhile, in soft start-up process, the peak point current of inductance L is controlled effectively.Work as load end
After short circuit disappears, boost circuits can well restart and return to normal output.
The above, only presently preferred embodiments of the present invention is not intended to limit the scope of the present invention.
Claims (13)
1. a kind of protection circuit, it is characterised in that be applied to boost circuits, the boost circuits are provided with first switch
The direct circuit for being input to output that is formed of parasitic diode；The protection circuit includes：
Over-current detection circuit, is configured to sample the first electric current for flowing through the first switch；And detection described first
Whether electric current meets first condition；There is excessively stream in the output current that the first condition characterizes the boost circuits；
First control circuit, is configured to, when first electric current meets the first condition, be controlled to second switch output first
Signal processed；
Second switch, is configured to response first control signal, disconnects the direct circuit.
2. protection circuit according to claim 1, it is characterised in that the over-current detection circuit, is configured to pass parallel connection
The mode of equivalent resistance is sampled to first electric current.
3. protection circuit according to claim 1, it is characterised in that the second switch, is configured to disconnect the boost
Circuit output end and the connection for loading.
4. protection circuit according to claim 3, it is characterised in that the second switch includes P-channel metal oxide
Semiconductor field PMOS.
5. protection circuit according to claim 1, it is characterised in that the protection circuit also includes：
Second control circuit, is configured to when first electric current meets the first condition, to first switch output the
Two control signals, and to the 3rd switch the 3rd control signal of output of the boost circuits, so that the boost circuits stop
Boosting modulation is carried out to input voltage；Wherein,
The second control control signal is reverse with the phase of the 3rd control signal；
During the boost circuits normal work, the second control circuit can be by the current sample to the described 3rd switch
The current loop circuit of the boost circuits is controlled, makes the boost circuit output ends voltages keep constant.
6. protection circuit according to claim 5, it is characterised in that the protection circuit also includes：
3rd control circuit, is configured to export the testing result of the over-current detection circuit to the first control circuit and the
Two control circuits.
7. protection circuit according to claim 6, it is characterised in that the 3rd control circuit, is additionally configured to：
Reception goes to enable signal；
Go to enable signal described in response, detect whether the output end voltage of the boost circuits meets second condition；Described second
Condition characterizes the input voltage of the output end voltage less than the boost circuits to preset value；And to the described first control
Circuit and second control circuit output testing result；
Correspondingly, the first control circuit, is additionally configured to meet the Article 2 when the output end voltage of the boost circuits
During part, the first control signal is exported to the second switch；
The second control circuit, is additionally configured to when the output end voltage of the boost circuits meets the second condition, to
The first switch exports the second control signal, and to the 3rd switch the 3rd control signal of output of the boost circuits；Its
In,
It is described to remove to enable signal for indicating to carry out over-current detection using the output voltage.
8. the protection circuit according to claim 6 or 7, it is characterised in that the 3rd control circuit, is additionally configured to
After boost circuits are closed, after reaching the stand-by period, the boost circuits and second switch are restarted；
The over-current detection circuit, is additionally configured to the first electricity that the detection in circuit restarting procedure flows through the first switch
Stream is sampled；And detect whether first electric current meets the first condition；
The first control circuit, is additionally configured to, when first electric current meets the first condition, be exported to second switch
First control signal, so that the second switch stops restarting；
Correspondingly, the second control circuit, is additionally configured to when first electric current meets the first condition, to described
One switch the second control signal of output, and the 3rd control signal is exported to the described 3rd switch, so that the boost circuits stop
Restarting.
9. a kind of guard method, it is characterised in that be applied to boost circuits, the boost circuits are provided with first switch
The direct circuit for being input to output that is formed of parasitic diode, methods described includes：
The first electric current to flowing through the first switch is sampled；
Detect whether first electric current meets first condition；The first condition characterizes the output current of the boost circuits
Generation excessively stream；
When first electric current meets the first condition, to second switch output the first control letter of the protection circuit
Number, to disconnect the direct circuit.
10. method according to claim 9, it is characterised in that the disconnection direct circuit, including：
Disconnect the connection of the boost circuit output ends and load.
11. methods according to claim 9, it is characterised in that methods described also includes：
When first electric current meets the first condition, the second control signal is exported to the first switch, and to described
3rd switch the 3rd control signal of output of boost circuits, so that the boost circuits stop carrying out boosting tune to input voltage
System；Wherein,
The second control control signal is reverse with the phase of the 3rd control signal.
12. methods according to claim 11, it is characterised in that methods described also includes：
When enable signal is received, go to enable signal described in response, whether the output end voltage of the detection boost circuits
Meet second condition；The second condition characterizes input voltage of the output end voltage less than the boost circuits to default
Value；
When the output end voltage of the boost circuits meets the second condition, controlled to second switch output first
Signal；The second control signal is exported to the first switch, and the 3rd control signal is exported to the described 3rd switch；Wherein,
It is described to remove to enable signal for indicating to carry out over-current detection using the output voltage.
13. method according to claim 11 or 12, it is characterised in that methods described also includes：
After boost circuits are closed, after reaching the stand-by period, the boost circuits and second switch are restarted；
Detect that the first electric current for flowing through the first switch is sampled in circuit restarting procedure；And detect described the
Whether one electric current meets the first condition；
When first electric current meets the first condition, first control signal is exported to the second switch, so that
The second switch stops restarting；
When first electric current meets the first condition, the second control signal is exported to the first switch, and to described
3rd switch the 3rd control signal of output, so that the boost circuits stop restarting.
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| CN107394749A (en) * | 2017-08-23 | 2017-11-24 | 惠州拓邦电气技术有限公司 | A kind of protection circuit |
| CN107659145A (en) * | 2017-10-23 | 2018-02-02 | 山东超越数控电子有限公司 | A kind of circuit structure of extension DC/DC power input voltage scopes |
| CN109713644A (en) * | 2017-10-26 | 2019-05-03 | 凌力尔特科技控股有限责任公司 | The hiccup overcurrent protection of synchronous multiphase switch convertor |
| CN111490567A (en) * | 2019-01-28 | 2020-08-04 | 青岛海信移动通信技术股份有限公司 | Mobile terminal and power supply control method thereof |
| CN112019051A (en) * | 2020-08-28 | 2020-12-01 | 无锡英迪芯微电子科技股份有限公司 | Buck converter with built-in over-current protection control circuit |
| CN112421577A (en) * | 2020-10-28 | 2021-02-26 | 爱士惟新能源技术(江苏)有限公司 | Rapid power-off protection method for photovoltaic inverter |
| CN112534668A (en) * | 2018-04-10 | 2021-03-19 | 德州仪器公司 | Boost converter short circuit protection |
| CN113612208A (en) * | 2021-07-20 | 2021-11-05 | Tcl华星光电技术有限公司 | Current limiting circuit |
| CN113794184A (en) * | 2021-09-17 | 2021-12-14 | 四川科陆新能电气有限公司 | Short circuit prevention circuit of direct current converter |
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| CN107659145A (en) * | 2017-10-23 | 2018-02-02 | 山东超越数控电子有限公司 | A kind of circuit structure of extension DC/DC power input voltage scopes |
| CN109713644A (en) * | 2017-10-26 | 2019-05-03 | 凌力尔特科技控股有限责任公司 | The hiccup overcurrent protection of synchronous multiphase switch convertor |
| CN109713644B (en) * | 2017-10-26 | 2022-11-08 | 亚德诺半导体国际无限责任公司 | Hiccup over-current protection for synchronous multiphase switching converter |
| CN112534668B (en) * | 2018-04-10 | 2023-09-29 | 德州仪器公司 | Boost converter short circuit protection |
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| CN111490567A (en) * | 2019-01-28 | 2020-08-04 | 青岛海信移动通信技术股份有限公司 | Mobile terminal and power supply control method thereof |
| CN112019051B (en) * | 2020-08-28 | 2021-06-15 | 无锡英迪芯微电子科技股份有限公司 | Buck converter with built-in over-current protection control circuit |
| CN112019051A (en) * | 2020-08-28 | 2020-12-01 | 无锡英迪芯微电子科技股份有限公司 | Buck converter with built-in over-current protection control circuit |
| CN112421577B (en) * | 2020-10-28 | 2022-06-21 | 爱士惟新能源技术(江苏)有限公司 | Rapid power-off protection method for photovoltaic inverter |
| CN112421577A (en) * | 2020-10-28 | 2021-02-26 | 爱士惟新能源技术(江苏)有限公司 | Rapid power-off protection method for photovoltaic inverter |
| CN113612208A (en) * | 2021-07-20 | 2021-11-05 | Tcl华星光电技术有限公司 | Current limiting circuit |
| CN113612208B (en) * | 2021-07-20 | 2022-10-04 | Tcl华星光电技术有限公司 | Current limiting circuit |
| CN113794184A (en) * | 2021-09-17 | 2021-12-14 | 四川科陆新能电气有限公司 | Short circuit prevention circuit of direct current converter |
| CN113794184B (en) * | 2021-09-17 | 2023-11-21 | 四川科陆新能电气有限公司 | Short circuit preventing circuit of direct current converter |
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