CN105704866B - Control circuit and control method - Google Patents
Control circuit and control method Download PDFInfo
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- CN105704866B CN105704866B CN201610266213.8A CN201610266213A CN105704866B CN 105704866 B CN105704866 B CN 105704866B CN 201610266213 A CN201610266213 A CN 201610266213A CN 105704866 B CN105704866 B CN 105704866B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
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Abstract
The present invention provides a kind of control circuit and control method, and the control circuit is connected with on-off circuit, the state of switching tube in controlling switch circuit.Circuit is controlled to include drive control circuit, power supply module and drop-down module.Drive control circuit is electrically connected with the switching tube in on-off circuit.Power supply module connecting valve circuit, electric current is provided for drive control circuit.Pull down module and be electrically connected with the drive control circuit, when on-off circuit is in off-mode, drop-down module pulls down the supply voltage of drive control circuit.
Description
Technical field
The present invention relates to field of LED drive, and more particularly to a kind of control circuit and control method.
Background technology
In non-isolated voltage-dropping type LED drive circuit, the supply voltage VCC of drive control circuit by circuit input voltage
There is provided with the difference of output voltage, as shown in Figure 1.In system closedown, when input voltage is reduced to close or equal to output electricity
During pressure, the supply voltage VCC voltages reduction of drive control circuit.When the supply voltage VCC of drive control circuit is reduced to driving
When controlling the shut-off threshold value VA of circuit, drive control circuit stops producing switching tube drive signal, and system shutdown switch, LED is born
It is zero to carry electric current, causes output voltage to reduce, accordingly, and because load is changed into unloaded, input voltage is raised again.Input voltage
The pressure difference for causing input voltage and output voltage is become big by rise and the reduction of output voltage, the supply voltage of drive control circuit
VCC is raised.When the supply voltage VCC of drive control circuit is increased to the unlatching threshold value VB of drive control circuit, drive control
Circuit produces drive signal and gives switching tube Q10, and circuit is started working, and the electric current of LED load rises again, and output voltage rises again,
Input voltage declines again.The input voltage of reduction and elevated output voltage make input voltage and output voltage difference and reduced, and drive
The supply voltage VCC of dynamic control circuit declines, system power down again.Such repeatedly several cycles, until input voltage as little as without
Untill method is powered to drive control circuit, there is backflash in shutdown in LED load.
The content of the invention
There is provided one kind control circuit and control method in order to overcome the deficiencies in the prior art by the present invention.
To achieve these goals, the present invention provides one kind and is connected with on-off circuit and switching tube in controlling switch circuit
The control circuit of state, control circuit includes drive control circuit, power supply module and drop-down module.Drive control circuit is electrical
Switching tube in connecting valve circuit.Power supply module connecting valve circuit, electric current is provided for drive control circuit.Pull down module electricity
Property connection drive control circuit, when on-off circuit be in off-mode when, drop-down module drop-down drive control circuit power supply electricity
Pressure.
In one embodiment of the invention, the drop-down module includes switch and detection module.Switch in parallel is in drive control
The power end and ground of circuit.Detection module is electrically connected with switch, the state of detection module detection switch circuit, at on-off circuit
When off-mode, detection module output switch drive signal, switch conduction pulls down the supply voltage of drive control circuit.
In one embodiment of the invention, detection module is the voltage being parallel between the power end of drive control circuit and ground
Detection module, voltage detection module detects the supply voltage of drive control circuit, when the supply voltage of drive control circuit is less than
During the shut-off threshold value of drive control circuit, characterize on-off circuit and be in off-mode.
In one embodiment of the invention, voltage detection module includes the first divider resistance being connected in series and the second partial pressure electricity
Resistance, comparator, the first transmission gate and the second transmission gate.First divider resistance is connected with the supply voltage of drive control circuit.
The normal phase input end of comparator is connected between the first divider resistance and the second divider resistance, the output end output switch of comparator
Drive signal.First transmission gate and the second transmission gate are connected between the inverting input of comparator and output end, are compared
The output of device determines the turn-on condition of the conducting state of the first transmission gate and the second transmission gate, the first transmission gate and the second transmission gate
On the contrary, first compares threshold value and inputted through the first transmission gate to comparator, second compares threshold value inputs to comparing through the second transmission gate
Device.
In one embodiment of the invention, detection module includes inductive current sampling resistor and inductive current slope detection electricity
Road, inductive current sampling resistor obtains inductive current during switching tube conducting, and inductive current slope detecting circuit is opened by detection
Close the slope of inductive current when pipe is turned on to obtain the change of input voltage, according to di/dt=(Vin-Vout)/L, work as di/
Dt characterizes on-off circuit and is in off-mode when being less than the slope threshold value of setting, di/dt is inductive current slope, and Vin is input
Voltage, Vout is output voltage, and L is inductance value.
In one embodiment of the invention, inductive current sampling resistor is connected between inductance and switching tube.
In one embodiment of the invention, when on-off circuit is Peak Current-Mode Controlled Circuit, detection module is electrically connected with and opened
Guan Guan, the ON time of detection switch pipe is characterized at on-off circuit when the ON time of switching tube is more than setting time threshold value
In off-mode.
In one embodiment of the invention, control circuit also includes current limliting module, and the current limliting module is connected with the switch.
In one embodiment of the invention, current limliting module is current-limiting resistance or current source.
In one embodiment of the invention, power supply module is resistance, and resistance needs to meet：(Vin-VB)/R1>VB/RS, Vin is
The supply voltage of on-off circuit, VB is the unlatching threshold value of drive control circuit, and R1 is the resistance value of power supply module, RSTo switch this
Resistance summation on bar branch road.
In one embodiment of the invention, power supply module is managed for JFET, and the output current of JFET pipes needs to meet：iJFET(@VCC
=VB)>VB/RS, iJFETFor the output current of JFET pipes, VCC is the supply voltage of drive control circuit, and VB is drive control electricity
The unlatching threshold value on road, RSTo switch the resistance summation on this branch road.
In one embodiment of the invention, switch as metal-oxide-semiconductor or triode.
Another aspect of the present invention also provides a kind of control method of above-mentioned control circuit, and this method is：With on-off circuit
Drop-down module is electrically connected with the drive control circuit being connected, when on-off circuit is in off-mode, drop-down module drop-down
The supply voltage of drive control circuit.
In summary, the control circuit that provides of the present invention and control method compared with prior art, with advantages below：
In system closedown, input voltage declines, and accordingly, the supply voltage of drive control circuit is also with decline.It is logical
Cross and drop-down module is electrically connected with drive control circuit, when the supply voltage of drive control circuit is less than drive control circuit
When turning off threshold value, drop-down module conducting pulls down the supply voltage of drive control circuit.The setting of drop-down module causes system to exist
During shutdown, the supply voltage of drive control circuit will not drive because the pressure difference of input voltage and output voltage changes and rebounds
Dynamic control circuit will not be repeatedly upper electric, so as to effectively inhibit system to load LED backflash in shutdown.Further, normal
During work, i.e., when the supply voltage of drive control circuit is more than the cut-in voltage of drive control circuit, drop-down module is not turned on,
The supply voltage of drive control circuit will not be pulled down, the efficiency of system will not be reduced.
For above and other objects of the present invention, feature and advantage can be become apparent, preferred embodiment cited below particularly,
And coordinate accompanying drawing, it is described in detail below.
Brief description of the drawings
Fig. 1 show the schematic block circuit diagram of existing LED drive circuit.
Fig. 2 show the theory diagram for the control circuit that the present invention is provided.
Fig. 3 show the circuit diagram of the control circuit of the offer of the embodiment of the present invention one.
Fig. 4 show the circuit diagram of the control circuit of the offer of the embodiment of the present invention two.
Fig. 5 show the circuit theory diagrams of detection module in Fig. 3 and Fig. 4.
Fig. 6 show the theory diagram of the control circuit of the offer of the embodiment of the present invention three.
Fig. 7 show the schematic diagram of inductive current slope detecting circuit in Fig. 6.
Fig. 8 show the theory diagram for the control circuit that another embodiment is provided.
Embodiment
Fig. 1 show existing LED drive circuit, and the supply voltage VCC of drive control circuit is by defeated in the circuit
Enter the difference of voltage and output voltage to provide.When system closedown, when input voltage is reduced to close or equal to output voltage,
Drive control circuit loads LED current vanishing due to electricity shortage power down.Now, input voltage is raised, output voltage drop
Low, i.e. the difference increase of input voltage and output voltage, drive control circuit is reworked, and load LED current rises again, input electricity
Pressure and the difference of output voltage decline again, the power down once more of drive control circuit, the vanishing again of load LED current, so make repeatedly
LED must be loaded and backflash phenomenon occur in shutdown.
In view of this, as shown in Fig. 2 the present invention provides a kind of be connected with on-off circuit 100 and controlling switch circuit 100
The control circuit of interior switching tube Q10 states.Circuit is controlled to include drive control circuit 1, power supply module 2, drop-down module 3.Driving
The switching tube Q10 for controlling circuit 1 to be electrically connected with on-off circuit 100.The connecting valve circuit 100 of power supply module 2, is drive control
Circuit 1 provides electric current.Pull down module 3 and be electrically connected with drive control circuit 1, when on-off circuit 100 is in off-mode, drop-down
Module 3 will pull down the supply voltage VCC of drive control circuit.
In the present embodiment, on-off circuit 100 is BUCK circuits.However, the present invention is not limited in any way to this.In other
In embodiment, on-off circuit 100 can be other on-off circuits such as Boost circuit.
The control circuit that the present invention is provided on drive control circuit 1 by being electrically connected with drop-down module 3, in system closedown
When, when the supply voltage VCC of drive control circuit 1 turns off threshold value VA less than it, drop-down module 3 is turned on, by drive control electricity
The supply voltage VCC drop-downs on road 1.Due to pulling down the presence of module 3, the supply voltage of drive control circuit 1 in system closedown
VCC is not in bounce-back, and drive control circuit 1 will not be repeatedly upper electric because of the change of input voltage and output voltage, so as to have
Effect suppresses load LED backflash in shutdown.
In the present embodiment, drop-down module 3 includes switch S10 and detection module 31.Switch S10 is connected in parallel on drive control electricity
The power end and ground on road 1.In the present embodiment, drive control circuit 1 is drives floatingly, and the ground of drive control circuit 1 is referred to
One reference ground, rather than the earth.The state of the detection switch circuit 100 of detection module 31, when on-off circuit 100 is in off-mode
When, the output switch drive signal of detection module 31, switch S10 conductings pull down the supply voltage VCC of drive control circuit 1, drive
The dynamic control complete power down of circuit 1.
In the present embodiment, detection module 31 is the voltage detecting being parallel between the power end of drive control circuit 1 and ground
Module, the supply voltage VCC of voltage detection module detection drive control circuit 1, when the supply voltage VCC of drive control circuit is low
When the shut-off threshold value VA of drive control circuit, characterize on-off circuit 100 and be in off-mode.In the present embodiment, voltage inspection
Survey module with switch S10 to be connected, voltage detection module output switch drive signal changes switch S10 switch to S10 is switched
State.However, the present invention is not limited in any way to this.In other embodiments, voltage detection module 31 can only and drive control
Circuit 1 is connected, and the switching drive signal detected is exported to drive control circuit 1, by the driving switch of drive control circuit 1
S10。
Drop-down module 3 concrete operating principle be：When the supply voltage VCC of drive control circuit is less than drive control circuit
During 1 shut-off threshold value VA, voltage detection module output switch drive signal is electric by drive control to S10, switch S10 conductings is switched
The supply voltage VCC drop-downs on road, the complete power down of drive control circuit 1.In the present embodiment, switch S10 is NMOS tube.However,
The present invention is not limited in any way to this.In other embodiments, switch S10 can be PNOS pipes or triode.
In the present embodiment, as shown in figure 3, voltage detection module includes the first divider resistance R20 for being connected in series and the
Two divider resistance R21, comparator U1, the first transmission gate U2 and the second transmission gate U3.First divider resistance R20 and drive control electricity
The supply voltage VCC on road is connected.Comparator U1 normal phase input end is connected to the first divider resistance R20 and the second divider resistance
Between R21, comparator U1 output end passes through phase inverter U4 output switch drive signals.First transmission gate U2 and the second transmission gate
U3 is connected between comparator U1 inverting input and output end, comparator U1 output determine the first transmission gate U2 and
Second transmission gate U3 conducting state, the first transmission gate U2 and the second transmission gate U3 turn-on condition are on the contrary, first compares threshold value
Vref1 is inputted to comparator U1 through the first transmission gate U2, and second compares threshold value Vref2 inputs to comparator through the second transmission gate U3
U1。
In the present embodiment, the first transmission gate U2 and the second transmission gate U3 are constituted by PMOS parallel with one another and NMOS.
However, the present invention is not limited in any way to this.
In the present embodiment, first compares threshold value Vref1 compares threshold value Vref2 more than second, and first compares threshold value Vref1
Compare threshold value Vref2 for VB*K, second for VA*K.VB is the unlatching threshold value of drive control circuit, and VA is drive control circuit
Threshold value is turned off, K is the second divider resistance R21 and the first divider resistance R20 and the ratio of the second divider resistance R20 sums.However,
The present invention is not limited in any way to this.In other embodiments, user can compare threshold value Vref1 according to circuit requirements modification first
Compare threshold value Vref2 with second.
Specifically, in system closedown, input voltage is gradually reduced, the supply voltage of corresponding drive control circuit
VCC value also will be reduced gradually, be inputted after the first divider resistance R20 and the second divider resistance R21 partial pressures to comparator U1's
Voltage Vindiv will also decrease.When the voltage Vindiv of input to comparator U1 compares threshold value Vref1 higher than first, comparator
U1 exports high level, turns into the output of voltage detection module after reverser U4.Because switch S10 is NMOS tube, therefore now
S10 shut-offs are switched, drive control circuit 1 produces drive signal to switching tube Q10, circuit normal work.Comparator U1 outputs
High level signal is separately input into the first transmission gate U2 and the second transmission gate U3, the first transmission gate U2 shut-off, the second transmission gate U3
Conducting, second, which compares threshold value Vref2, inputs to comparator U1 through the second transmission gate U3 and is compared with voltage Vindiv.
It is more than and drives when the supply voltage VCC of drive control circuit drops to less than the unlatching threshold value VB of drive control circuit
During the shut-off threshold value VA of dynamic control circuit, it is compared, now compares because voltage Vindiv is only compared threshold value Vref2 with second
Device U1 still exports high level, and voltage detection module output low level switchs S10 still in off state.Only work as drive control
The supply voltage VCC of circuit is dropped to less than after the shut-off threshold value VA of drive control circuit, comparator U1 output low levels.First
Transmission gate U2 is turned on, the second transmission gate U3 shut-offs, and voltage detection module output high level, and switch S10 is turned on drive control
The supply voltage VCC drop-downs of circuit.The complete power down of drive control circuit 1, is stopped, and the electric current on load LED is zero, will not
Produce backflash.
In the present embodiment, power supply module 2 is resistance R10.In system closedown, due to input voltage reduction, driving control
When the supply voltage VCC of circuit processed drops below the shut-off threshold value VA of drive control circuit, switch S10 conductings.Now, as
The resistance R10 current limitings effect of power supply module 2, the discharge current of control input voltage.In view of when system starts, driving is controlled
The supply voltage VCC of circuit processed is less than shut-off threshold value VA, switch S10 conductings, to prevent the drive control circuit when system starts
Supply voltage VCC to do not reach its open threshold value VB, it is necessary to set power supply module 2 output current be more than flow through switch S10
The electric current of the branch road at place.In the present embodiment, resistance R10 needs to meet：(Vin-VB)/R1>VB/RS, Vin is on-off circuit
Supply voltage, VB is the unlatching threshold value of drive control circuit, and R1 is resistance R10 resistance value, RSTo switch on this branch road
Resistance summation.
Corresponding with above-mentioned control circuit, the present invention also provides a kind of control method.This method be with on-off circuit
Drop-down module 3 is electrically connected with the 100 drive control circuits 1 being connected, when on-off circuit 100 is in off-mode, drop-down
The supply voltage of the drop-down of module 3 drive control circuit 1, the complete power down of drive control circuit 1 is prevented effectively from input voltage and defeated
Go out the problem of drive control circuit is repeatedly upper electric when voltage changes.
Specifically, in system closedown, when the supply voltage VCC of drive control circuit is less than drive control circuit 1
When turning off threshold value VA, drop-down module 3 pulls down the supply voltage VCC of drive control circuit.In the present embodiment, drop-down module 3 is wrapped
Switch S10 and detection module 31 are included, and detection module 31 is voltage detection module.Switch S10 is connected in parallel on drive control circuit 1
Between power end and ground.Voltage detection module 31 is equally connected in parallel between the power end of drive control circuit 1 and ground.In this implementation
In example, voltage detection module is connected with switch S10, and voltage detection module output switch drive signal is opened to S10, change is switched
Close S10 on off state.However, the present invention is not limited in any way to this.In other embodiments, voltage detection module can only with
Drive control circuit 1 is connected, and the switching drive signal detected is exported to drive control circuit 1, by drive control circuit 1
Driving switch S10.
In the present embodiment, switch S10 is NMOS tube.However, the present invention is not limited in any way to this.In other embodiments
In, switch S10 can be PNOS pipes or triode.
Embodiment two
The present embodiment and embodiment one and its change are essentially identical, and difference is：First：Power supply module 2 is managed for JFET
Q11；Second, control circuit also includes current limliting module, and current limliting module is connected with switch S10.
When system starts, when the supply voltage VCC of drive control circuit is lower than its cut-in voltage VB, due to now opening
S10 conductings are closed, in order to ensure that the supply voltage VCC of drive control circuit can reach cut-in voltage VB within a certain period of time, are being opened
Close current limliting module of being connected on S10 branch road.In the present embodiment, current limliting module is resistance R11.However, the present invention does not make to this
It is any to limit.In other embodiments, current limliting module can be current source.
Likewise, when opening, the supply voltage VCC of drive control circuit can reach cut-in voltage VB in view of system, need
The electric current for setting JFET pipes Q11 to export is more than the electric current for flowing through current limliting module, i.e. the electric current of JFET pipes Q11 outputs needs to meet：
iJFET(@VCC=VB)>VB/RS, iJFETFor JFET pipes Q11 output current, VCC is the supply voltage of drive control circuit, VB
For the unlatching threshold value of drive control circuit, RSFor the resistance summation on switch S10 this branch road, in the present embodiment, RSFor resistance
Conducting resistance of the R11 resistance plus switch S10.In other embodiments, when current limliting module is current source, JFET pipes Q11
The electric current of output needs to meet：iJFET(@VCC=VB)>Is, is are the current value that current source is exported.
Embodiment three
The present embodiment and embodiment one and its change are essentially identical, and difference is：In the present embodiment, detection module 31 is wrapped
Inductive current sampling resistor R31 and inductive current slope detecting circuit 311 are included, inductive current sampling resistor R31 obtains switching tube
Inductive current during conducting, inductive current slope when inductive current slope detecting circuit 311 is turned on by detection switch pipe come
The change of input voltage is obtained, according to di/dt=(Vin-Vout)/L, switch is characterized when di/dt is less than setting slope threshold value
Circuit is in off-mode.Wherein, di/dt is inductive current slope, and Vin is input voltage, and Vout is output voltage, and L is electricity
Feel L1 inductance value.
Inductive current sampling resistor R31 is connected between inductance L1 and switching tube Q10.In the present embodiment, such as Fig. 6 institutes
Show, the ground of drive control circuit 1 is connected between inductive current sampling resistor R31 and inductance L1.This connected mode can be obtained
Inductive current during switching tube Q10 turn-on and turn-off, and in switching tube Q10 turn-on and turn-off, inductive current sampled point ISP's
Voltage is all positive voltage, facilitates the processing of circuit.However, the present invention is not limited in any way to this., can be by other embodiments
The ground and inductive current sampled point of drive control circuit are exchanged, obtained electricity of being sampled so in switching tube Q10 turn-on and turn-off
Inducing current sampled point ISP voltage is all negative value.Or, in other embodiments, inductive current sampling resistor R31 can be such as Fig. 8
Mode be attached, inductive current sampling resistor R31 connects with switching tube Q10 but is not attached to inductance in this kind of connected mode
In L1 discharge loop.Therefore, this kind of mode inductive current sampling resistor R31 is only able to detect electricity when switching tube Q10 is turned on
Inducing current.Due to need to only use inductive current when switching tube Q10 is turned in the present invention, therefore above-mentioned inductive current is sampled
Resistance R31 connected mode can be with.
As shown in fig. 7, the present embodiment provide inductive current slope detecting circuit 311 include electric capacity C31, resistance R32 and
Comparison circuit U31.Electric capacity C31 one end is connected with inductive current sampled point ISP, electric capacity the C31 other end and resistance R32 phases
Connection, inductive current sampled point ISP voltage charges for electric capacity C31.Comparison circuit U31 first input end is connected to electric capacity
C31 and resistance R32 common port, another input connect voltage ratio compared with threshold value Vref3.The inductive current that the present embodiment is provided is oblique
The slope of inductive current is converted to magnitude of voltage and is compared by rate detection circuit 311.
Due to the electric current i=C (dv/dt) on electric capacity C31, C is electric capacity C31 value, and dv/dt is inductive current sampled point
ISP voltage slope.When inductive current sampled point ISP voltage slope dv/dt is big, the electric current on electric capacity C31 is big, resistance
Voltage on R32 is high, therefore can judge that inductive current sampled point ISP voltage is oblique by the voltage on detection resistance R32
Rate dv/dt, that is, obtain inductive current slope di/dt.Specifically：When 100 normal work of on-off circuit, input voltage vin
Larger, switching tube Q10 conductings, inductive current sampled point ISP voltage slope dv/dt is big, and the voltage on resistance R32 is more than voltage
Compare threshold value Vref3, comparison circuit U31 output high level.In the present embodiment, switch S10 is NMOS tube, therefore more electric
Road U31 output terminates a reverser.However, not connecing phase inverter when switching S10 and being PMOS.When comparison circuit U31 outputs
During high level, phase inverter exports low level and is not turned on to S10, switch S10 is switched, and drop-down module 3 does not work.And when system is in
During off-mode, input voltage vin reduces, switching tube Q10 conductings, now inductive current sampled point ISP voltage slope dv/dt
Small, the voltage on resistance R32 is small, when the voltage on resistance R32 is less than voltage ratio compared with threshold value Vref3, comparison circuit U31 outputs
It is changed into high level after low level, inverted device to act on switch S10, switch S10 conductings, drop-down module 3 is electric by drive control
The voltage VCC drop-downs on road 1, the complete power down of drive control circuit 1.
Present embodiments provide it is a kind of detect the change of input voltage vin by detecting the slope of inductive current so that
Judge whether system is in off-mode.In other embodiments, when on-off circuit 100 is Peak Current-Mode Controlled Circuit, electricity
Inducing current slope di/dt is small, to reach the peak value of control, then needs larger ON time.Therefore, detection module can electrically connect
Switching tube Q10 is met, by judging the size of switching tube Q10 ON times, to judge the size of input voltage, so as to judge system
Whether off-mode is in.
In summary, the control circuit and control method that the present invention is provided are in system closedown, and input voltage declines, accordingly
, the supply voltage of drive control circuit is also with decline.By being electrically connected with drop-down module on drive control circuit, work as drive
When the supply voltage of dynamic control circuit is less than the shut-off threshold value of drive control circuit, drop-down module is turned on drive control circuit
Supply voltage is pulled down.The setting of drop-down module causes system in shutdown, and the supply voltage of drive control circuit will not be because of input
The pressure difference change of voltage and output voltage and rebound, drive control circuit will not be repeatedly upper electric, so as to effectively inhibit and be
System loads LED backflash in shutdown.Further, in normal work, i.e., driven when the supply voltage of drive control circuit is more than
During the cut-in voltage of dynamic control circuit, drop-down module is not turned on, and the supply voltage of drive control circuit will not be pulled down, no
The efficiency of system can be reduced.
It is any to know this skill although the present invention is disclosed above by preferred embodiment, but is not limited to the present invention
Skill person, without departing from the spirit and scope of the present invention, can make a little change and retouching, therefore protection scope of the present invention is worked as
It is defined depending on claims scope claimed.
Claims (12)
1. one kind control circuit, it is characterised in that the state of switching tube, institute in the simultaneously controlling switch circuit that is connected with on-off circuit
Stating control circuit includes：
Drive control circuit, is electrically connected with the switching tube in on-off circuit；
Power supply module, connecting valve circuit provides electric current for drive control circuit；
Module is pulled down, the drive control circuit is electrically connected with, when on-off circuit is in off-mode, drop-down module drop-down is driven
The supply voltage of dynamic control circuit, the drop-down module includes：
Switch, is parallel to the power end and ground of drive control circuit；
Detection module, is electrically connected with the switch, and the state of the detection module detection switch circuit is closed when on-off circuit is in
During machine state, detection module output switch drive signal, switch conduction pulls down the supply voltage of drive control circuit.
2. control circuit according to claim 1, it is characterised in that the detection module is to be parallel to the drive control
Voltage detection module between the power end and ground of circuit, the power supply electricity of the voltage detection module detection drive control circuit
Pressure, when the supply voltage of drive control circuit is less than the shut-off threshold value of drive control circuit, characterizes on-off circuit and is in shutdown
State.
3. control circuit according to claim 2, it is characterised in that the voltage detection module includes：
The first divider resistance and the second divider resistance being connected in series, the supply voltage of the first divider resistance and drive control circuit
It is connected；Comparator, the normal phase input end of comparator is connected between the first divider resistance and the second divider resistance, comparator
Output end output switch drive signal；
First transmission gate and the second transmission gate, are connected between the inverting input of comparator and output end, comparator
Output determines the turn-on condition phase of the conducting state of the first transmission gate and the second transmission gate, the first transmission gate and the second transmission gate
Instead, first compares threshold value and is inputted through the first transmission gate to comparator, and second compares threshold value inputs to comparator through the second transmission gate.
4. control circuit according to claim 1, it is characterised in that the detection module includes inductive current sampling resistor
With inductive current slope detecting circuit, the inductive current sampling resistor obtains inductive current during switching tube conducting, inductance electricity
The slope of inductive current when slope detecting circuit is turned on by detection switch pipe is flowed to obtain the change of input voltage, according to
Di/dt=(Vin-Vout)/L, on-off circuit is characterized when di/dt is less than the slope threshold value of setting in off-mode, di/dt
For inductive current slope, Vin is input voltage, and Vout is output voltage, and L is inductance value.
5. control circuit according to claim 4, it is characterised in that the inductive current sampling resistor be connected to inductance and
Between switching tube.
6. control circuit according to claim 1, it is characterised in that when the on-off circuit is Peak Current-Mode Controlled Circuit
When, the detection module is electrically connected with switching tube, the ON time of detection switch pipe, when the ON time of switching tube is more than setting
On-off circuit is characterized during time threshold and is in off-mode.
7. control circuit according to claim 1, it is characterised in that the control circuit also includes current limliting module, described
Current limliting module is connected with the switch.
8. control circuit according to claim 7, it is characterised in that the current limliting module is current-limiting resistance or current source.
9. control circuit according to claim 1, it is characterised in that the power supply module is resistance, the resistance need to expire
Foot：(Vin-VB)/R1>VB/RS, Vin is the supply voltage of on-off circuit, and VB is the unlatching threshold value of drive control circuit, and R1 is
The resistance value of power supply module, RSTo switch the resistance summation on this branch road.
10. control circuit according to claim 1, it is characterised in that the power supply module is managed for JFET, the JFET pipes
Output current need meet：iJFET(@VCC=VB)>VB/RS, iJFETFor the output current of JFET pipes, VCC is drive control circuit
Supply voltage, VB be drive control circuit unlatching threshold value, RSTo switch the resistance summation on this branch road.
11. control circuit according to claim 1, it is characterised in that the switch is metal-oxide-semiconductor or triode.
12. a kind of control method of control circuit, it is characterised in that electric on the drive control circuit being connected with on-off circuit
Property connection drop-down module, when on-off circuit be in off-mode when, drop-down module pull down drive control circuit supply voltage, institute
Stating drop-down module includes：
Switch, is parallel to the power end and ground of drive control circuit；
Detection module, is electrically connected with the switch, and the state of the detection module detection switch circuit is closed when on-off circuit is in
During machine state, detection module output switch drive signal, switch conduction pulls down the supply voltage of drive control circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| CN106300944B (en) | 2016-08-06 | 2018-12-14 | 杰华特微电子（张家港）有限公司 | Over-current control circuit crosses method of flow control and the power-supply system using it |
| CN108172184A (en) * | 2018-01-02 | 2018-06-15 | 京东方科技集团股份有限公司 | Shutdown discharge circuit and display module |
| CN109121246B (en) * | 2018-07-24 | 2021-02-19 | 苏州浪潮智能科技有限公司 | Control circuit of LED on server and server |
| JP7156047B2 (en) * | 2019-01-16 | 2022-10-19 | 株式会社島津製作所 | Chromatography device and load switch circuit |
| CN112051883B (en) * | 2020-08-06 | 2022-11-29 | 苏州浪潮智能科技有限公司 | Chip control method for realizing quick current response |
| CN112650377B (en) * | 2020-12-22 | 2022-09-02 | 海光信息技术股份有限公司 | I2C bus pull-up power supply method, circuit and chip |
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| CN101835302B (en) * | 2009-03-13 | 2013-04-24 | 建兴电子科技股份有限公司 | Drive circuit for controlling quick closedown of light-emitting diode (LED) |
| JP5576892B2 (en) * | 2012-03-13 | 2014-08-20 | オムロンオートモーティブエレクトロニクス株式会社 | LED lighting and disconnection detection control device |
| CN104883799B (en) * | 2015-06-12 | 2018-11-23 | 昂宝电子（上海）有限公司 | Control method, control circuit, system and LED lamp for LED driving |
| CN205726544U (en) * | 2016-04-26 | 2016-11-23 | 杰华特微电子（杭州）有限公司 | Control circuit |
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Address after: Room 901-23, 9 / F, west 4 building, Xigang development center, 298 Zhenhua Road, Sandun Town, Xihu District, Hangzhou City, Zhejiang Province, 310030 Patentee after: Jiehuate Microelectronics Co.,Ltd. Address before: Room 424, building 1, 1500 Wenyi West Road, Cangqian street, Yuhang District, Hangzhou City, Zhejiang Province Patentee before: JOULWATT TECHNOLOGY (HANGZHOU) Co.,Ltd. |
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