CN104868448A - Switching power supply, control circuit and method for switching power supply, and open-circuit protection setting circuit for switching power supply - Google Patents
Switching power supply, control circuit and method for switching power supply, and open-circuit protection setting circuit for switching power supply Download PDFInfo
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Abstract
The invention relates to a switching power supply, a control circuit and method for the switching power supply, and an open-circuit protection setting circuit for the switching power supply. The control circuit for the switching power supply comprises a power-driven tube and the open-circuit protection setting circuit connected with one or more external pins of the control circuit; the open-circuit protection setting circuit comprises a time selection module, a first comparator and an RS trigger; the time selection module selects one of a plurality of preset reference times as an internal reference time according to the connection state of the one or more external pins; one input end of the first comparator is connected with the time selection module so as to receive the internal reference time; the other input end of the first comparator is used for receiving the inductance demagnetization time of the switching power supply; the first comparator is used for outputting a protection signal when the inductance demagnetization time is shorter than the internal reference time; the RS trigger is connected to the open-circuit protection setting circuit and used for receiving the protection signal, so that the RS trigger can output a triggering signal to switch off the power-driven tube.
Description
Technical field
The present invention relates to Switching Power Supply, particularly relate to and circuit and correlation method are set for the control circuit of Switching Power Supply and open-circuit-protection.
Background technology
Switching Power Supply is a kind of power supply being maintained burning voltage or electric current output by the turn-on and turn-off of control power drive pipe (such as transistor, field effect transistor, controllable silicon thyratron etc.).Compared with traditional linear power supply, the efficiency of Switching Power Supply is higher, loss and heating less, is therefore with a wide range of applications in electronic technology.
For Switching Power Supply, the energy of power outputting section is mainly stored in inductance in the mode of electric field/magnetic field conversion, and subsequently to load supplying.If load open circuit, the magnetic field energy in inductance cannot discharge, and inductance two ends there will be high pressure, likely the various device of breakdown switch power source internal.Therefore, need to detect output open circuit situation in time, and avoid when output open circuit being detected output voltage too high.Fig. 1 shows a kind of existing buck configuration Switching Power Supply, and comprise open-circuit-protection and arrange module 101, it is connected to pin ROVP, and pin ROVP is through resistor R2 ground connection.Open-circuit-protection arranges module 101 can make Switching Power Supply enter guard mode when open circuit overvoltage being detected, and output voltage Vout is now open-circuit-protection voltage Vovp.By the size of regulating resistance R2, different output open circuit protection voltage Vovp can be set.
But the open-circuit-protection voltage Vovp antijamming capability controlled by resistor is very poor, is subject to the impact of the external factor such as moist electric leakage, hot environment, PCB plate material, causes Vovp voltage deviation set point, even cause power-supply system work not normal.Therefore, the open-circuit-protection for Switching Power Supply that there is a need in the field to provide a kind of improvement arranges circuit.
Summary of the invention
The mode arranging open-circuit-protection voltage Vovp for traditional switch power acquisition resistance easily causes output open circuit to protect the comparatively large problem even lost efficacy of voltage deviation because of factors such as humidity electric leakage, external disturbance, the open-circuit-protection for Switching Power Supply that the invention provides a kind of improvement arranges circuit and method.
According to one embodiment of present invention, provide a kind of control circuit for Switching Power Supply, described control circuit comprises: power drive pipe; Open-circuit-protection arranges circuit, it is connected at least one external terminal of described control circuit, described open-circuit-protection arranges circuit and comprises: selection of time module, and its connection status based at least one external terminal described selects one of multiple default fiducial time as the internal reference time; And first comparator, an one input is connected to described selection of time module to receive the described internal reference time and its another input receives inductance demagnetization time of described Switching Power Supply, and described first comparator is output protection signal when the described inductance demagnetization time is less than the described internal reference time; And rest-set flip-flop, it is connected to described open-circuit-protection and arranges circuit to receive described guard signal, and described guard signal makes described rest-set flip-flop export the triggering signal turning off described power drive pipe.
In one embodiment, described control circuit also comprises: zero passage detection module, and it is connected to the inductance of described Switching Power Supply and described rest-set flip-flop and exports Continuity signal when the discharging current zero passage of described inductance to described rest-set flip-flop with the triggering signal making described rest-set flip-flop export power drive pipe described in conducting; And second comparator, it is connected to the sampling resistor of described Switching Power Supply and described rest-set flip-flop and sampled voltage signal on described sampling resistor exports to make described rest-set flip-flop the triggering signal turning off described power drive pipe to described rest-set flip-flop higher than exporting cut-off signals during reference voltage.
In one embodiment, described control circuit also comprises: logic and driver module, and it is connected to described rest-set flip-flop to receive described triggering signal and carry out conducting according to described triggering signal or turn off described power drive pipe.
In one embodiment, described open-circuit-protection arranges circuit and also comprises: pin status detection module, and it is connected at least one external terminal described to detect the connection status of at least one external terminal described and output combinational logic value; Register, it is connected to described pin status detection module to receive and store described combinational logic value and the described combinational logic value of the connection status of at least one external terminal described for reflection is supplied to described selection of time module.
In one embodiment, described pin status detection module is connected to enabling signal and is controlled by described enabling signal.
In one embodiment, for each external terminal at least one external terminal described, described pin status detection module comprises: current source, and it is connected to this external terminal; 3rd comparator, it receives the magnitude of voltage on this external terminal and described magnitude of voltage and reference voltage is made comparisons, and the output signal of described 3rd comparator indicates the connection status of this external terminal and is output to described register.
In one embodiment, for each external terminal at least one external terminal described, described pin status detection module also comprises: switch, and it is connected to described current source and is controlled by described enabling signal.
In one embodiment, described enabling signal is useful signal between the described Switching Power Supply starting period.
In one embodiment, the connection status of each external terminal is ground connection, unsettled and connect the one of senior middle school.
According to one embodiment of present invention, provide a kind of open-circuit-protection for Switching Power Supply and circuit is set, comprise: pin status detection module, it is connected at least one external terminal with the combinational logic value of the connection status of the connection status output reflection at least one external terminal described that detect at least one external terminal described; Register, it is connected to described pin status detection module to receive and to store described combinational logic value; Selection of time module, it is connected to described register to receive described combinational logic value and to select one of multiple default fiducial time as the internal reference time according to described combinational logic value; And first comparator; an one input is connected to described selection of time module to receive the described internal reference time and its another input receives inductance demagnetization time of described Switching Power Supply, described first comparator when the described inductance demagnetization time is less than the described internal reference time output protection signal to turn off the power drive pipe of described Switching Power Supply.
In one embodiment, the connection status of each external terminal is ground connection, unsettled and connect the one of senior middle school.
In one embodiment, at least one external terminal described is two external terminals, each external terminal has two kinds of connection status, and described pin status detection module exports one of four combinational logic values, and described selection of time module has four default fiducial times.
In one embodiment, at least one external terminal described is three external terminals, each external terminal has two kinds of connection status, and described pin status detection module exports one of eight combinational logic values, and described selection of time module has eight default fiducial times.
In one embodiment, the described inductance demagnetization time is the turn-off time of the power drive pipe of described Switching Power Supply.
In one embodiment, described pin status detection module is connected to enabling signal and is controlled by described enabling signal.
In one embodiment, for each external terminal at least one external terminal described, described pin status detection module comprises: current source, and it is connected to this external terminal; Second comparator, it receives the magnitude of voltage on this external terminal and described magnitude of voltage and reference voltage is made comparisons, and the output signal of described second comparator indicates the connection status of this external terminal and is output to described register.
In one embodiment, for each external terminal at least one external terminal described, described pin status detection module also comprises: switch, and it is connected to described current source and is controlled by described enabling signal.
In one embodiment, described enabling signal is useful signal between the described Switching Power Supply starting period.
According to one embodiment of present invention, provide a kind of Switching Power Supply, it comprises control circuit as above or open-circuit-protection as above arranges circuit.
According to one embodiment of present invention, provide a kind of control method for Switching Power Supply, comprising: the connection status detecting at least one external terminal of the control circuit of described Switching Power Supply; Connection status based at least one external terminal described selects one of multiple default fiducial time as the internal reference time; The inductance of described Switching Power Supply demagnetization time and described internal reference time are made comparisons; And when the described inductance demagnetization time is less than the described internal reference time output protection signal to turn off the power drive pipe of described Switching Power Supply.
In one embodiment, described control method also comprises: provide electric current to each external terminal at least one external terminal described; Detect the magnitude of voltage on each external terminal; And the magnitude of voltage on each external terminal and reference voltage are made comparisons the connection status determining each external terminal.
In one embodiment, described control method also comprises: control to provide electric current to each external terminal at least one external terminal described by enabling signal.
In one embodiment, described enabling signal is useful signal between the described Switching Power Supply starting period.
In one embodiment, the connection status of each external terminal is ground connection, unsettled and connect the one of senior middle school.
In one embodiment, at least one external terminal described is two external terminals, and each external terminal has two kinds of connection status, and described multiple default fiducial time is four fiducial times corresponding with the connection status of described two external terminals.
In one embodiment, at least one external terminal described is three external terminals, and each external terminal has two kinds of connection status, and described multiple default fiducial time is eight fiducial times corresponding with the connection status of described three external terminals.
In one embodiment, the described inductance demagnetization time is the turn-off time of the power drive pipe of described Switching Power Supply.
As mentioned above, the invention provides a kind of novel open-circuit-protection for Switching Power Supply arrange circuit and method and adopt this open-circuit-protection to arrange the Switching Power Supply of circuit and method.The present invention can the connection status of external terminal of sense switch power control circuit; the mode of data segments configuration is used to realize different open-circuit-protection voltage Vovp; both improve the antijamming capability of circuit, eliminated outer meeting resistance again, enhance the stability of power-supply system.In addition, the present invention can detect the connection status of external terminal when circuit start, and stops detecting after startup completes, thus without the need to increasing the normal power consumption of chip.
Accompanying drawing explanation
Fig. 1 shows a kind of schematic diagram of existing Switching Power Supply.
Fig. 2 shows according to an embodiment of the inventionly has the schematic diagram that open-circuit-protection arranges the Switching Power Supply of circuit.
Fig. 3 shows the schematic diagram that open-circuit-protection according to an embodiment of the invention arranges circuit.
Fig. 4 shows the schematic diagram that open-circuit-protection according to an embodiment of the invention arranges the pin status detection module in circuit.
Embodiment
Below in conjunction with specific embodiments and the drawings, the invention will be further described, but it will be apparent to one skilled in the art that the following description and drawings are only exemplary, and should not limit the scope of the invention.The element in accompanying drawing with same or similar Reference numeral can operate similarly.
Fig. 2 shows according to an embodiment of the inventionly has the schematic diagram that open-circuit-protection arranges the Switching Power Supply of circuit.For ease of understand and exemplarily non-limiting, below with reference to the adjusting and voltage-reduction switch power supply shown in Fig. 2, circuit is arranged to open-circuit-protection according to the present invention and is described specifically.It should be understood that; open-circuit-protection of the present invention arranges the Switching Power Supply that circuit is not limited to be applied to as shown in Figure 2; but be applicable to various Switching Power Supply, such as isolated/non-isolated Switching Power Supply, positive activation type/inverse-excitation type switch power-supply, self-activated switch power supply, push-pull type Switching Power Supply, step down switching regulator, booster switcher power supply and reversible type Switching Power Supply etc.
As shown in Figure 2, this Switching Power Supply can comprise input voltage vin, start-up circuit R1 and C2, sustained diode 1, inductance L 1, output capacitor C1, output voltage Vout, control circuit 20 and sampling resistor Rcs.Load (such as, LED) can be coupled to the two ends of output capacitor C1, thus is powered by output voltage Vout.Control circuit 20 can be the form of packaged chip, and can comprise multiple external terminal, external terminal VCC, A, B, DRAIN, CS as shown in Figure 2 etc.Control circuit 20 also can comprise other pin (not shown) as required.Control circuit 20 comprises power drive pipe M1, and it can be connected between pin DRAIN and CS, thus is connected to one end of inductance L 1 and the positive pole of sustained diode 1 via pin DRAIN.The input that control circuit 20 carrys out control switch power supply by the turn-on and turn-off controlling power drive pipe M1 is powered, thus controls the output voltage Vout of this Switching Power Supply.Power drive pipe M1 can be any switch module being applicable to Switching Power Supply, such as transistor, field effect transistor, controllable silicon thyratron etc.Such as, the drain electrode of power drive pipe M1 can be connected to pin DRAIN, and source electrode can be connected to pin CS, and grid can be controlled by the signal GT in control circuit 20.Power drive pipe M1 be also not limited to as shown in Figure 2 with the connected mode of act as listed above, but can connect suitably in dissimilar Switching Power Supply and power with the input of control switch power supply.
Particularly, control circuit 20 also comprises zero passage detection module 201, and it is coupled to inductance L 1 to detect the discharging current Iout whether zero passage of inductance L 1 via pin DRAIN, and exports Continuity signal S1 when the discharging current Iout zero passage of inductance L 1 being detected; Comparator 202, an one input is connected to sampling resistor Rcs to detect the sampled voltage signal on sampling resistor Rcs via pin CS, its another input receives reference voltage Vcs, and detecting that the sampled voltage signal of Rcs on sampling resistor exports cut-off signals R1 higher than during reference voltage Vcs; Open-circuit-protection arranges circuit 203, and its connection status detecting external terminal A, B correspondingly to arrange the value of output open circuit protection voltage Vovp, and provides cut-off signals R2 to carry out corresponding open-circuit-protection when output open circuit being detected; Rest-set flip-flop 204, its reception arranges output S1, R1 and R2 of circuit 203 from zero passage detection module 201, comparator 202 and open-circuit-protection and correspondingly provides triggering signal Q; And logic and driver module 205, it receives the triggering signal Q from rest-set flip-flop 204 and correspondingly controls the turn-on and turn-off of power drive pipe M1 through drive singal GT.Control circuit 20 can also comprise other protective circuits with the state of sense switch power supply; and when abnormal conditions being detected output protection signal to rest-set flip-flop 204; thus effectively make power drive pipe M1 turn off via logic and driver module 205, make control circuit 20 or whole Switching Power Supply enter guard mode.
At work, input voltage vin provides enabling signal VCC between resistance R1 and capacitor C2, and enabling signal VCC can power to control circuit 20.Such as, when Switching Power Supply starts, capacitor C2 charges until enabling signal VCC enters normal work higher than making control circuit 20 after a certain threshold value, and such as, control circuit 20 controls power drive pipe M1 conducting.When the M1 conducting of power drive pipe, input voltage vin is charged to capacitor C1 and inductance L 1, and diode D1 ends, and electric current flow to ground from energization input through load, inductance L 1, power drive pipe M1 and sampling resistor Rcs.During this period, electric current increases, and the sampled voltage signal on sampling resistor Rcs increases gradually, when sampled voltage signal increases above reference voltage Vcs, the output switching activity of comparator 202, thus rest-set flip-flop 204 exports triggering signal Q makes logic and driver module 205 switch-off power driving tube M1.
After power drive pipe M1 turns off, the electric charge on capacitor C1 powers to the load, and the energy simultaneously stored in inductance L 1 powers to the load via sustained diode 1.Zero passage detection module 201 detects the discharging current Iout of inductance L 1, and when the discharging current Iout zero passage of inductance L 1 (such as, when being reduced to 0 from positive current) send Continuity signal S1, rest-set flip-flop 204 is made to export triggering signal Q, logic and driver module 205 conducting power driving tube M1, thus input voltage vin is charged to inductance L 1 and capacitor C1 again.In this way, power drive pipe M1 periodically turn-on and turn-off, provide the output voltage Vout of expectation at switched power output.
When load open circuit, output voltage Vout can rise gradually, and the demagnetization time Toff of inductance L 1 shortens, and open-circuit-protection arranges circuit 203 and judges that Switching Power Supply exports overvoltage of whether opening a way by comparing Toff and internal reference time Tovp.Particularly, when meeting the following conditions, open-circuit-protection arranges circuit 203 can judge output open circuit overvoltage and output protection signal R2:
Wherein Toff is that inductance (such as, L1) demagnetizes the time, and Tovp is the fiducial time of chip internal setting, L is inductance value (such as, the inductance value of inductance L 1), and Vcs is the reference voltage threshold of comparator 202, Vout is output voltage, and Rcs is sampling resistor.Open-circuit-protection arranges circuit 203 can export cut-off signal R2 when open circuit overvoltage being detected; rest-set flip-flop 204 correspondingly exports triggering signal Q to make logic and driver module 205 switch-off power driving tube M1; make Switching Power Supply enter guard mode, output voltage Vout is now open-circuit-protection voltage Vovp.Therefore by regulating internal reference time Tovp, open-circuit-protection arranges circuit 203 can not initiate guard mode in the same time, thus provides different output open circuit protection voltage Vovp, as described in detail referring to Fig. 3.
After switch power supply system enters guard mode, VCC voltage starts to decline; When VCC arrives under-voltage protection threshold value, switch power supply system will be restarted.Simultaneous Switching power-supply system constantly detects load condition (that is, overvoltage of whether opening a way), if trouble shooting, this switch power supply system can restart normal work.
Fig. 3 shows the schematic diagram that open-circuit-protection according to an embodiment of the invention arranges circuit 203.Open-circuit-protection arranges circuit 203 and comprises: pin status detection module 301, register 302, selection of time module 303 and comparator 304.Pin status detection module 301 is connected to (control circuit 20 such as shown in Fig. 2) at least one external terminal is to detect the connection status of this pin.Exemplarily, two external terminals A, B have been shown in Fig. 2 and 3.In specific implementation, can use a pin or two or more pin, the present invention is unrestricted in this regard.Each external terminal can have multiple connection status, such as ground connection, unsettled, connect height (connecing chip power) etc., can select according to actual needs.Pin status detection module 301 carrys out output combinational logic value by the connection status detecting each external terminal.Such as, if use two external terminals A, B, each pin has ground connection and unsettled two kinds of connection status (can represent by logical value 0 and 1 respectively), then pin status detection module 301 can export 00,01,10,11 4 kind of connection status, namely 2
2; If there are 3 external terminal A, B, C respectively having 2 kinds of connection status, then can provide 2
3namely eight kinds of connection status export.In specific implementation, can configuration pin number and pin connection status as required.
The combinational logic value that pin status detection module 301 exports can be received by register 302 and store, and is output to selection of time module 303 subsequently.Selection of time module 303 receives the combinational logic value from register 302, and correspondingly selects different internal reference time Tovp, such as selects Tovp1 based on combinational logic value 00, and select Tovp2 based on combinational logic value 01, the rest may be inferred.Tovp1, Tovp2, Tovp3, Tovp4 etc. can arrange circuit 203 inside at open-circuit-protection and pre-set the internal reference time.In another embodiment, as required the Tovp time reasonably can be divided into some sections, the digital state one_to_one corresponding exported with pin status detection module 301, thus realize data segments configuration.For example, two external terminals A, B can realize 4 kinds of different protection voltages and arrange.Such as when A pin ground connection, B pin are unsettled, pin status detection module 301 detects that the connection status of A, B pin is after 0,1, and selection of time module 303 selects Tovp2 as the fiducial time of open-circuit-protection voltage.
Tovp fiducial time selected by selection of time module 303 is output to comparator 304, and receiving inductance demagnetization time Toff gone back by comparator 304.When comparator 304 detects that inductance demagnetization time Toff is less than selected Tovp fiducial time (that is, open-circuit-protection circuit 203 is set judge output open circuit overvoltage), output protection signal R2.See Fig. 2, this guard signal R2 is provided to rest-set flip-flop 204, and it exports triggering signal Q and makes logic and driver module 205 switch-off power driving tube M1, thus Switching Power Supply enters guard mode.As mentioned above, inductance demagnetization time Toff can calculate shown in (1), or directly can adopt turn-off time of power drive pipe M1 of Switching Power Supply.
As above; by configuration open-circuit-protection, each external terminal that circuit 203 will detect is set (such as; pin A, B) connection status; such as be set to ground connection, unsettled, connect one of high; just Tovp fiducial time selected by circuit 203 can be set control on demand open-circuit-protection, corresponding open-circuit-protection voltage Vovp is provided thus.
The modules (as pin status detection module 301, register 302, selection of time module 303) that open-circuit-protection is arranged in circuit 203 can be controlled by enabling signal Start.Enabling signal Start can be the signal startup stage of indicating Switching Power Supply whether to be in.Such as, the startup stage of by the enabling signal VCC detected as described above with reference to FIG. 2, enabling signal Start can determine whether Switching Power Supply is in, and be effective time Switching Power Supply is in startup stage.Such as in Switching Power Supply startup or after restarting, enabling signal Start can carry out clearing process to modules, again detects external terminal state.In addition, after Switching Power Supply has started (it is in normal work period), enabling signal Start has become invalid, thus pin status detection module 301 is without the need to detecting the connection status of external terminal A, B etc. constantly.Now, Tovp fiducial time during Switching Power Supply startup stage selected by selection of time module 303 is still output to comparator 304, thus open-circuit-protection arranges circuit 203 can detect open circuit overvoltage constantly at Switching Power Supply duration of work.In this way, improve open-circuit-protection arrange the job stability of circuit 203 and reduce its power consumption.
Fig. 4 shows the schematic diagram that open-circuit-protection according to an embodiment of the invention arranges the pin status detection module 301 in circuit 203.Arrange for open-circuit-protection each external terminal (such as, pin A) that circuit 203 will detect, pin status detection module 301 can comprise circuit structure as shown in Figure 4 to detect the connection status of this pin.Exemplarily non-limiting, Fig. 4 is a kind of rough schematic of pin connection status testing circuit implementation of pull-up current.Pin status detection module 301 also can adopt other structures (such as pull-down current source) to detect pin connection status.This kind of circuit can detect two kinds of connection status of external terminal A, such as ground connection or unsettled.When control circuit chip enable, inner enabling signal start controllable switch K1 closes, and Iup is inner pull-up current source, if now external terminal A ground connection, so voltage VA is low level; If now external terminal A is unsettled, so voltage VA is the high level close to supply voltage vdd.VA voltage and suitable reference level Vref are made comparisons by comparator (comp) 401, draw corresponding logic level values, it reflects the connection status of now external terminal A (such as, ground connection or unsettled, correspondingly output logic level 0 or 1), and be transferred to register 302 via optional NOR gate 402.Such as, NOR gate 402 only just exports effective logical value Y when inner enabling signal start is effective.In this way, pin status detection module 301 can detect the connection status of each external terminal, and output combinational logic value.After control circuit chip enable completes, start signal is by cut-off switch K1 and close measuring ability, does not increase electric current when chip is normally worked.
Fig. 4 shows a kind of exemplary approach that pin status detection module 301 detects the connection status of external terminal A, and it judges pin connection status by detecting pin voltage.Those skilled in the art can conceive any other implementation to detect the connection status of external terminal A, such as, judge pin connection status by detecting pin electric current.The present invention is unrestricted in this regard.
As mentioned above, the invention provides a kind of novel open-circuit-protection for Switching Power Supply arrange circuit and method and adopt this open-circuit-protection to arrange the Switching Power Supply of circuit and method.By arranging the connection status of the external terminal of switching power source control circuit; open-circuit-protection arranges the connection status of these external terminals of electric circuit inspection; the mode of data segments configuration is used to realize different open-circuit-protection voltage Vovp; both improve the antijamming capability of circuit; eliminate outer meeting resistance again, enhance the stability of power-supply system.
Such scheme when chip enable by the connection status of start signal controlling pin status detection module 301 detection chip external terminal, by pin pull-up current or pull-down current, can detect the impedance of pin, judges the connection status of pin; After chip enable completes, pull-up or pull-down current can be disconnected, thus not increase the running current of chip.By pull-up or pull-down current are arranged higher, the interference effect of the external factor such as pin moist electric leakage, hot environment, PCB plate material can be reduced further, thus improve the accuracy of open-circuit-protection voltage Vovp.
By reference to the accompanying drawings embodiments of the invention are described above.Should be appreciated that; above-described embodiment is just to explanation of the present invention; instead of limitation of the present invention; any innovation and creation do not exceeded in spirit of the present invention; include but not limited to the replacement of the change to local structure, the type to components and parts or model; and the replacement of other unsubstantialities or amendment, all fall within scope.
Claims (27)
1. for a control circuit for Switching Power Supply, it is characterized in that, described control circuit comprises:
Power drive pipe;
Open-circuit-protection arranges circuit, and it is connected at least one external terminal of described control circuit, and described open-circuit-protection arranges circuit and comprises:
Selection of time module, its connection status based at least one external terminal described selects one of multiple default fiducial time as the internal reference time; And
First comparator, an one input is connected to described selection of time module to receive the described internal reference time and its another input receives inductance demagnetization time of described Switching Power Supply, and described first comparator is output protection signal when the described inductance demagnetization time is less than the described internal reference time; And
Rest-set flip-flop, it is connected to described open-circuit-protection and arranges circuit to receive described guard signal, and described guard signal makes described rest-set flip-flop export the triggering signal turning off described power drive pipe.
2. control circuit as claimed in claim 1, is characterized in that, also comprise:
Zero passage detection module, it is connected to the inductance of described Switching Power Supply and described rest-set flip-flop and exports Continuity signal when the discharging current zero passage of described inductance to described rest-set flip-flop with the triggering signal making described rest-set flip-flop export power drive pipe described in conducting; And
Second comparator, it is connected to the sampling resistor of described Switching Power Supply and described rest-set flip-flop and sampled voltage signal on described sampling resistor exports to make described rest-set flip-flop the triggering signal turning off described power drive pipe to described rest-set flip-flop higher than exporting cut-off signals during reference voltage.
3. control circuit as claimed in claim 2, is characterized in that, also comprise:
Logic and driver module, it is connected to described rest-set flip-flop to receive described triggering signal and carry out conducting according to described triggering signal or turn off described power drive pipe.
4. control circuit as claimed in claim 1, it is characterized in that, described open-circuit-protection arranges circuit and also comprises:
Pin status detection module, it is connected at least one external terminal described to detect the connection status of at least one external terminal described and output combinational logic value; And
Register, it is connected to described pin status detection module to receive and store described combinational logic value and the described combinational logic value of the connection status of at least one external terminal described for reflection is supplied to described selection of time module.
5. control circuit as claimed in claim 4, it is characterized in that, described pin status detection module is connected to enabling signal and is controlled by described enabling signal.
6. control circuit as claimed in claim 5, it is characterized in that, for each external terminal at least one external terminal described, described pin status detection module comprises:
Current source, it is connected to this external terminal; And
3rd comparator, it receives the magnitude of voltage on this external terminal and described magnitude of voltage and reference voltage is made comparisons, and the output signal of described 3rd comparator indicates the connection status of this external terminal and is output to described register.
7. control circuit as claimed in claim 6, it is characterized in that, for each external terminal at least one external terminal described, described pin status detection module also comprises:
Switch, it is connected to described current source and is controlled by described enabling signal.
8. control circuit as claimed in claim 5, it is characterized in that, described enabling signal is useful signal between the described Switching Power Supply starting period.
9. control circuit as claimed in claim 1, is characterized in that, the connection status of each external terminal is ground connection, unsettled and connect the one of senior middle school.
10. the open-circuit-protection for Switching Power Supply arranges a circuit, it is characterized in that, comprising:
Pin status detection module, it is connected at least one external terminal with the combinational logic value of the connection status of the connection status output reflection at least one external terminal described that detect at least one external terminal described;
Register, it is connected to described pin status detection module to receive and to store described combinational logic value;
Selection of time module, it is connected to described register to receive described combinational logic value and to select one of multiple default fiducial time as the internal reference time according to described combinational logic value; And
First comparator; an one input is connected to described selection of time module to receive the described internal reference time and its another input receives inductance demagnetization time of described Switching Power Supply, described first comparator when the described inductance demagnetization time is less than the described internal reference time output protection signal to turn off the power drive pipe of described Switching Power Supply.
11. open-circuit-protections as claimed in claim 10 arrange circuit, it is characterized in that, the connection status of each external terminal is ground connection, unsettled and connect the one of senior middle school.
12. open-circuit-protections as claimed in claim 10 arrange circuit; it is characterized in that; at least one external terminal described is two external terminals; each external terminal has two kinds of connection status; described pin status detection module exports one of four combinational logic values, and described selection of time module has four default fiducial times.
13. open-circuit-protections as claimed in claim 10 arrange circuit; it is characterized in that; at least one external terminal described is three external terminals; each external terminal has two kinds of connection status; described pin status detection module exports one of eight combinational logic values, and described selection of time module has eight default fiducial times.
14. open-circuit-protections as claimed in claim 10 arrange circuit, it is characterized in that, the described inductance demagnetization time is turn-off time of the power drive pipe of described Switching Power Supply.
15. open-circuit-protections as claimed in claim 10 arrange circuit, and it is characterized in that, described pin status detection module is connected to enabling signal and is controlled by described enabling signal.
16. open-circuit-protections as claimed in claim 15 arrange circuit, it is characterized in that, for each external terminal at least one external terminal described, described pin status detection module comprises:
Current source, it is connected to this external terminal; And
Second comparator, it receives the magnitude of voltage on this external terminal and described magnitude of voltage and reference voltage is made comparisons, and the output signal of described second comparator indicates the connection status of this external terminal and is output to described register.
17. open-circuit-protections as claimed in claim 16 arrange circuit, it is characterized in that, for each external terminal at least one external terminal described, described pin status detection module also comprises:
Switch, it is connected to described current source and is controlled by described enabling signal.
18. open-circuit-protections as claimed in claim 15 arrange circuit, it is characterized in that, described enabling signal is useful signal between the described Switching Power Supply starting period.
19. 1 kinds of Switching Power Supplies, is characterized in that, described Switching Power Supply comprises control circuit as claimed in any one of claims 1-9 wherein or the open-circuit-protection according to any one of claim 10-18 arranges circuit.
20. 1 kinds, for the control method of Switching Power Supply, comprising:
Detect the connection status of at least one external terminal of the control circuit of described Switching Power Supply;
Connection status based at least one external terminal described selects one of multiple default fiducial time as the internal reference time;
The inductance of described Switching Power Supply demagnetization time and described internal reference time are made comparisons; And
When the described inductance demagnetization time is less than the described internal reference time, output protection signal is to turn off the power drive pipe of described Switching Power Supply.
21. control methods as claimed in claim 20, is characterized in that, also comprise:
Electric current is provided to each external terminal at least one external terminal described;
Detect the magnitude of voltage on each external terminal; And
Magnitude of voltage on each external terminal and reference voltage are made comparisons the connection status determining each external terminal.
22. control methods as claimed in claim 21, is characterized in that, also comprise:
Control to provide electric current to each external terminal at least one external terminal described by enabling signal.
23. control methods as claimed in claim 22, is characterized in that, described enabling signal is useful signal between the described Switching Power Supply starting period.
24. control methods as claimed in claim 20, is characterized in that, the connection status of each external terminal is ground connection, unsettled and connect the one of senior middle school.
25. control methods as claimed in claim 20, it is characterized in that, at least one external terminal described is two external terminals, and each external terminal has two kinds of connection status, and described multiple default fiducial time is four fiducial times corresponding with the connection status of described two external terminals.
26. control methods as claimed in claim 20, it is characterized in that, at least one external terminal described is three external terminals, and each external terminal has two kinds of connection status, and described multiple default fiducial time is eight fiducial times corresponding with the connection status of described three external terminals.
27. control methods as claimed in claim 20, is characterized in that, the described inductance demagnetization time is turn-off time of the power drive pipe of described Switching Power Supply.
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| CN201510348972.4A CN104868448A (en) | 2015-06-19 | 2015-06-19 | Switching power supply, control circuit and method for switching power supply, and open-circuit protection setting circuit for switching power supply |
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| CN201510348972.4A CN104868448A (en) | 2015-06-19 | 2015-06-19 | Switching power supply, control circuit and method for switching power supply, and open-circuit protection setting circuit for switching power supply |
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| CN201510348972.4A Pending CN104868448A (en) | 2015-06-19 | 2015-06-19 | Switching power supply, control circuit and method for switching power supply, and open-circuit protection setting circuit for switching power supply |
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