CN105407608A - Control circuit, LED constant current driving control circuit and control method thereof - Google Patents
Control circuit, LED constant current driving control circuit and control method thereof Download PDFInfo
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- CN105407608A CN105407608A CN201510895952.9A CN201510895952A CN105407608A CN 105407608 A CN105407608 A CN 105407608A CN 201510895952 A CN201510895952 A CN 201510895952A CN 105407608 A CN105407608 A CN 105407608A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention discloses a control circuit. The control circuit comprises a high-frequency oscillating circuit, a peak current detection circuit, a filter circuit, an error comparison circuit, a logic control circuit and a power tube, wherein the high-frequency oscillating circuit is used for generating a block signal; the peak current detection circuit is used for detecting and controlling peak current flowing through the power tube, and outputting an overcurrent control signal when the peak current flowing through the power tube reaches a preset peak current; the filter circuit is used for detecting voltage of a current sensing resistor, and generating a voltage average value signal; the error comparison circuit is used for receiving the voltage average value signal generated by the filter circuit, comparing the voltage average value signal with a built-in level reference signal, and outputting an average value control signal; and the logic control circuit is used for receiving the clock signal, the overcurrent control signal and the average value control signal, and outputting a power tube control signal to control on or off of the power tube, thereby making current of an external load electrically connected with the control circuit reach a preset target current.
Description
Technical field
The present invention relates to electronic technology field, particularly relate to a kind of control circuit, LED constant current Drive and Control Circuit and control method thereof.
Background technology
As shown in Figure 1, a kind of traditional non-isolation type LED drive circuit, it comprises main power inductance Lm, master power switch pipe MP, peak current detection resistance Rcs.When the electric current in Lm arrives certain value, when the voltage detected on resistance Rcs exceedes internal reference voltage Vref, control circuit is by peak value comparison method unit, and switching signal generating unit and driver element turn off master power switch pipe MP.Ls is auxiliary winding, Rd and Ru is the divider resistance of auxiliary winding, demagnetize in the common port access control circuit of Rd and Ru the comparator of detecting unit, when in main power inductance Lm during electric current vanishing, the common port voltage of described Rd and Ru reduces to zero, comparator exports demagnetization end signal ZXC, and open switching tube by switching signal generating unit and driver element, the control forming next cycle starts.
The BUCK mode of the LED drive power of the non-isolation type shown in Fig. 1 mainly voltage-dropping type, adopt the control mode of critical discontinuous, in the occasion that output current is larger, the advantage of critical discontinuous control mode is that control mode is simple, and the current stress in inductance is little.But when critical discontinuous control mode is used in the occasion of high voltage-small current, because its inductance value is too large, cause the whole lifting of driving power volume and the increase of cost.
Along with the development of high-voltage LED lamp pearl and LED drive power are to the more and more harsh requirement of cost and volume, low cost, the demand of small size gets more and more.The demand of high output voltage, little load current, high-frequency application is more and more universal, higher output voltage can improve conversion efficiency, higher driving frequency can the less inductance value of demand, adopt I-shaped inductance or paster series inductance can reduce the volume of driving power, reduce the cost adopting magnetic core EE inductance.For increasing high voltage-small current in the market, especially the application scenario of filament lamp, many LED chip factories start to trend towards discontinuous control mode to design LED drive power, and traditional LED Drive and Control Circuit is more and more difficult to the demand meeting this application.
Summary of the invention
In order to solve the problem, the invention provides a kind of control circuit, LED constant current Drive and Control Circuit and control method thereof, which employs full closed loop control technology, so that output current precision is high, not with input voltage, the impact of output voltage and inductance value change; And adopt the hop cycle control technology of fixed frequency, fixed current peak value, can discontinuous mode be operated in control circuit, and then the chip inductor of more small size can be used; Moreover the present invention does not need auxiliary winding to carry out demagnetization detection, and then reduces cost.
According to an aspect of of the present present invention, provide a kind of control circuit, it comprises: a high-frequency oscillating circuits, a peak current detection circuit, a filter circuit, an application condition circuit, a logic control circuit and power tube; Wherein, described high-frequency oscillating circuits is electrically connected with described logic control circuit, and described high-frequency oscillating circuits is for generation of the clock signal of a fixed frequency; Described peak current detection circuit is electrically connected with the drain electrode of described logic control circuit and described power tube respectively, described peak current detection circuit is used for the peak current that detection and control flows through described power tube, when the peak current flowing through described power tube reaches pre-set peak value electric current, output overcurrent control signal; Described filter circuit is electrically connected with the source electrode of described power tube and the current sense resistor of outside that is electrically connected with described control circuit respectively, and described filter circuit for detecting the voltage of described current sense resistor, and produces an average voltage value signal; Described application condition circuit is electrically connected with described filter circuit and described logic control circuit respectively, the average voltage value signal that described application condition circuit produces for receiving described filter circuit, and compare with built-in level reference signal, and export mean value control signal; Described logic control circuit is electrically connected with the grid of described power tube, the mistake flow control signals that described logic control circuit produces for the clock signal produced that receives described high-frequency oscillating circuits, described peak current detection circuit and the mean value control signal that described application condition circuit produces, and power output pipe control signal, to control conducting or the shutoff of described power tube, and then the electric current of the external loading be electrically connected with described control circuit is made to reach goal-selling electric current.
In one embodiment of this invention, described filter circuit is RC formula filter circuit.
In one embodiment of this invention, when the mean value control signal that described application condition circuit exports is high level, electric current on the external loading be electrically connected with described control circuit is less than goal-selling electric current, and described power tube is allowed to open and charges to external loading.
In one embodiment of this invention, described power tube control signal becomes high level at the rising edge of described clock signal, the conducting after described power tube control signal becomes high level of described power tube, the maximum ON time of described power tube determined by the high level duty ratio of described clock signal and frequency of oscillation.
In one embodiment of this invention, when flowing through the pre-set peak value electric current that the electric current on described power tube reaches set by described peak current detection circuit, the mistake flow control signals that described peak current detection circuit exports becomes high level, and then described power tube is turned off after described power tube control signal becomes low level.
In one embodiment of this invention, when the mean value control signal that described application condition circuit exports is low level, electric current on the external loading be electrically connected with described control circuit is greater than goal-selling electric current, and described power tube is prohibited to open and charges to external loading.
In one embodiment of this invention, described control circuit cuts out the power tube of current period conducting, makes the target current that the electric current flowing through external loading equals default.
In one embodiment of this invention, described control circuit, by skipping one or more clock signal period to forbid power tube conducting, makes the target current that the electric current flowing through external loading equals default.
According to another aspect of the present invention, propose a kind of LED drive chip, described chip comprises above-mentioned control circuit, and described LED drive chip, in order to control the electric current of the load be electrically connected with described LED drive chip, makes the electric current of described load be goal-selling electric current.
According to another aspect of the present invention, propose a kind of LED constant current Drive and Control Circuit, it comprises: an input ac voltage source, a rectifier bridge, an input capacitance, a current sense resistor, an inductance, a load, a fly-wheel diode and above-mentioned LED drive chip; The two ends in described input ac voltage source are electrically connected to the common connecting point of parallel connection two rectification branch roads of described rectifier bridge respectively; One end of described input capacitance is electrically connected to a wherein tie point of described common connecting point, and the other end of described input capacitance is electrically connected to wherein another tie point of described common connecting point; The D pin of described LED drive chip is electrically connected to one end of described input capacitance, and the CS pin of described LED drive chip is electrically connected to one end of described current sense resistor and the negative pole of described fly-wheel diode respectively, the GND pin ground connection of described LED drive chip; The other end of described current sense resistor is electrically connected to ground connection after described inductance and described load successively; The positive pole of described fly-wheel diode is electrically connected to the other end of described input capacitance and ground connection simultaneously; Wherein, described rectifier bridge and described input capacitance are in order to change the AC-input voltage in described input ac voltage source into DC input voitage; Described current sense resistor is in order to detect and to set the average current flowing through described load; Described LED drive chip is in order to the voltage by gathering on described current sense resistor, and the DC input voitage controlling to change transmits energy, so that make the electric current of described load be goal-selling electric current to described inductance and described load.
In one embodiment of this invention, when described power tube control signal becomes high level and after described power tube conducting, described DC input voitage is charged to described inductance by the power tube of described LED drive chip, described current sense resistor and described load at the rising edge of described clock signal.
In one embodiment of this invention, the mistake flow control signals exported when described peak current detection circuit becomes high level and described power tube is closed have no progeny, and described inductance carries out afterflow by described fly-wheel diode.
According to another aspect of the present invention, propose a kind of LED constant current drived control method, adopt above-mentioned control circuit, comprise the following steps: high-frequency oscillating circuits produces the clock signal of a fixed frequency and is sent to logic control circuit; Peak current detection circuit detection and control flows through the peak current of power tube, and when the peak current flowing through described power tube reaches pre-set peak value electric current, described peak current detection circuit output overcurrent control signal is also sent to logic control circuit; Filter circuit detects the voltage of current sense resistor, and produces an average voltage value signal to be sent to described application condition circuit; Application condition circuit receives the average voltage value signal that described filter circuit produces, and compares with built-in level reference signal, and output mean value controls signal to described logic control circuit; The mistake flow control signals that described logic control circuit receives the clock signal that described high-frequency oscillating circuits produces, described peak current detection circuit produces and the mean value control signal that described application condition circuit produces, and power output pipe control signal, to control conducting or the shutoff of described power tube, and then the electric current of the external loading be electrically connected with described control circuit is made to reach goal-selling electric current.
In one embodiment of this invention, when the mean value control signal that described application condition circuit exports is high level, electric current on the external loading be electrically connected with described control circuit is less than goal-selling electric current, and described power tube is allowed to open and charges to external loading; Or when the mean value control signal that described application condition circuit exports is low level, the electric current on the external loading be electrically connected with described control circuit is greater than goal-selling electric current, described power tube is prohibited conducting and charges to external loading.
In one embodiment of this invention, described control circuit close current period conducting power tube or by skipping one or more clock signal period to forbid power tube conducting, make the target current that the electric current flowing through external loading equals default.
The invention has the advantages that, control circuit of the present invention, LED drive chip, LED constant current Drive and Control Circuit and control method thereof are by have employed full closed loop control technology, so that output current precision is high, not with input voltage, the impact of output voltage and inductance value change; And adopt the hop cycle control technology of fixed frequency, fixed current peak value, can discontinuous mode be operated in control circuit, and then the chip inductor of more small size can be used; Moreover the present invention does not need auxiliary winding to carry out demagnetization detection, and then reduces cost.In addition, components and parts used in the present invention are less, and control mode is relatively simple, and reliability is strong.
Accompanying drawing explanation
Fig. 1 is the circuit connection diagram of traditional non-isolation type LED drive circuit;
Fig. 2 is the inside connection diagram of the control circuit of one embodiment of the invention;
Fig. 3 is the constant-current LED Drive and Control Circuit of one embodiment of the invention;
Fig. 4 is the working timing figure of the control circuit in the constant-current LED Drive and Control Circuit shown in Fig. 3;
Fig. 5 is the steps flow chart schematic diagram of one embodiment of the invention LED constant current drived control method.
Embodiment
Elaborate below in conjunction with the embodiment of accompanying drawing to control circuit provided by the invention, LED drive chip, constant-current LED Drive and Control Circuit and control method thereof.
Shown in Figure 2, the invention provides a kind of control circuit, it comprises: high-frequency oscillating circuits 1, peak current detection circuit 2, filter circuit 3, application condition circuit 4, logic control circuit 5 and a power tube MP; Wherein, described high-frequency oscillating circuits 1 is electrically connected with described logic control circuit 5, and described high-frequency oscillating circuits 1 is for generation of the clock signal clk of a fixed frequency; Described peak current detection circuit 2 is electrically connected with the drain electrode of described logic control circuit 5 and described power tube MP respectively, described peak current detection circuit 2 flows through the peak current of described power tube MP for detection and control, when the peak current flowing through described power tube MP reaches pre-set peak value electric current, output overcurrent control signal OCP; Described filter circuit 3 is electrically connected (referring to Fig. 3) with the source electrode of described power tube MP and the current sense resistor Rcs of outside that is electrically connected with described control circuit respectively, the described voltage filter of momentary fluctuation, for detecting the voltage of described current sense resistor Rcs, is produced the signal CS_avg of the mean value of an approximate described voltage by described filter circuit 3 simultaneously; Described application condition circuit 4 is electrically connected with described filter circuit 3 and described logic control circuit 5 respectively, the average voltage value signal CS_avg that described application condition circuit 4 produces for receiving described filter circuit 3, and compare with built-in level reference signal Vref, and export mean value control signal COMPO; Described logic control circuit 5 is electrically connected with the grid of described power tube MP, the mistake flow control signals OCP that described logic control circuit 5 produces for clock signal clk, the described peak current detection circuit 2 receiving described high-frequency oscillating circuits 1 and produce and the mean value control signal COMPO that described application condition circuit 4 produces, and power output pipe control signal GATE, to control conducting or the shutoff of described power tube MP, and then the electric current of the external loading be electrically connected with described control circuit is made to reach goal-selling electric current.It is noted that the electric current of external loading described herein refers to the average current flowing through external loading.
Specifically, in the present embodiment, described filter circuit 3 is RC formula filter circuit.And in other embodiments, described filter circuit 3 is not limited to this, such as, it can be RLC formula filter circuit etc.
Further, when the mean value control signal COMPO that described application condition circuit 4 exports is high level, electric current on the external loading be electrically connected with described control circuit is less than default target current, and described power tube MP is allowed to open and charges to external loading.
Shown in Figure 4, described power tube control signal GATE becomes high level at the rising edge of described clock signal clk, described power tube MP conducting after described power tube control signal GATE becomes high level, the maximum ON time of described power tube MP determined by the high level duty ratio of described clock signal clk and frequency of oscillation.That is, the maximum ON time of described power tube MP is by the duty ratio of oscillator and determines the cycle of oscillation of high-frequency oscillating circuits, and the product of duty ratio and cycle of oscillation is oscillator signal (i.e. clock signal) and is in the time that high level occupies, therefore change frequency of oscillation and duty ratio can change maximum ON time.Described power tube control signal GATE rises to high level and is determined by described clock signal clk.
And when flowing through the pre-set peak value electric current that the electric current on described power tube MP reaches set by described peak current detection circuit 2, the mistake flow control signals OCP that described peak current detection circuit 2 exports becomes high level, and then described power tube MP is turned off after described power tube control signal GATE becomes low level.
When the mean value control signal COMPO that described application condition circuit 4 exports is low level, the electric current on the external loading be electrically connected with described control circuit is greater than goal-selling electric current, and described power tube MP is prohibited to open and charges to external loading.Now, described control circuit cuts out the power tube MP of current period conducting.Or described control circuit forbids power tube MP conducting by skipping one or more clock signal period, and to make the electric current flowing through external loading equal goal-selling electric current, the energy namely realizing control circuit transmission equals the energy of load consumption.
The present invention also provides a kind of LED drive chip U1 (marking in Fig. 3), it comprises the control circuit such as shown in Fig. 2, described LED drive chip U1, in order to control the electric current of the load be electrically connected with described LED drive chip U1, makes the electric current of described load be goal-selling electric current.
Shown in Figure 3, the present invention also provides a kind of LED constant current Drive and Control Circuit, comprising: an input ac voltage source Vac, a rectifier bridge BD1, an input capacitance Cin, a current sense resistor Rcs, an inductance L 1, load (not marking in figure), a sustained diode 1 and above-mentioned LED drive chip U1; The two ends of described input ac voltage source Vac are electrically connected to the common connecting point of parallel connection two rectification branch roads of described rectifier bridge BD1 respectively; One end of described input capacitance Cin is electrically connected to a wherein tie point of described common connecting point, and the other end of described input capacitance Cin is electrically connected to wherein another tie point of described common connecting point; The VCC pin of described LED drive chip U1 is electrically connected to a constant voltage constant current power Cvcc, the D pin (i.e. the Drain pin of the power tube MP of described LED drive chip U1 inside) of described LED drive chip U1 is electrically connected to one end of described input capacitance Cin, the CS pin of described LED drive chip U1 is electrically connected to one end of described current sense resistor Rcs and the negative pole of described sustained diode 1 respectively, the GND pin ground connection of described LED drive chip U1; The other end of described current sense resistor Rcs is electrically connected to ground connection after described inductance L 1 and described load successively, and the other end of described current sense resistor Rcs is electrically connected to the GND pin of described LED drive chip U1 simultaneously; The positive pole of described sustained diode 1 is electrically connected to the other end of described input capacitance Cin and ground connection simultaneously; Wherein, described rectifier bridge BD1 and described input capacitance Cin is in order to change the AC-input voltage of described input ac voltage source Vac into DC input voitage; Described current sense resistor Rcs is in order to detect and to set the average current flowing through described load; Described LED drive chip U1 is in order to the voltage by gathering on described current sense resistor Rcs, and the DC input voitage controlling to change transmits energy, so that make the electric current flowing through described load be goal-selling electric current to described inductance L 1 and described load.Wherein, described LED drive chip U1 and peripheral circuit (comprising current sense resistor Rcs, inductance L 1, load and sustained diode 1 etc.) form a closed control loop.
Furthermore, when described power tube control signal GATE becomes high level and after described power tube MP conducting, described DC input voitage is charged to described inductance L 1 by the power tube MP of described LED drive chip U1, described current sense resistor Rcs and described load at the rising edge of described clock signal clk.Wherein, the electric current of described inductance L 1 is flow through as shown in Figure 4.
The mistake flow control signals OCP exported when described peak current detection circuit 2 becomes low level and described power tube MP is closed have no progeny, and described inductance L 1 carries out afterflow by described sustained diode 1.
To sum up, control circuit of the present invention, LED drive chip and adopt the constant-current LED Drive and Control Circuit of described LED drive chip (voltage that described LED drive chip U1 samples on described current sense resistor Rcs with utilizing the CS pin complete period is for the electric current of control flow check overload by adopting full closed loop control technology, therefore be full closed loop control), so that output current precision is high, not with input voltage, the impact of output voltage and inductance value change; And adopt fixed frequency, fixed current peak value hop cycle control technology (according to Fig. 4, the power tube MP of described LED drive chip U1 is unlatching each clock cycle, has partial periodicity to be skipped; The number of skip cycle is realized by closed control loop, main manifestations is the level height of described mean value control signal COMPO, if when described mean value control signal COMPO is low level, then cycle of oscillation can be skipped), can discontinuous mode be operated in control circuit, and then the chip inductor of more small size can be used; Moreover, the present invention does not need auxiliary winding to carry out demagnetization detection, and (passing through in prior art demagnetizes detects to judge whether described power tube MP opens, and the unlatching of power tube MP of the present invention determined by closed control loop, main manifestations is the level height of described mean value control signal COMPO, if when described mean value control signal COMPO is high level, described power tube MP can be opened at the rising edge of clock signal.And the closedown of described power tube MP determined by the described flow control signals OCP and described mean value control signal COMPO that crosses), and then reduce cost.In addition, components and parts used in the present invention are less, and control mode is relatively simple, and reliability is strong.
In addition, the present invention also provides a kind of LED constant current drived control method, adopts above-mentioned control circuit, said method comprising the steps of:
Step S510: high-frequency oscillating circuits produces the clock signal of a fixed frequency and is sent to logic control circuit.
Step S520: peak current detection circuit detection and control flows through the peak current of power tube, when the peak current flowing through described power tube reaches pre-set peak value electric current, described peak current detection circuit output overcurrent control signal is also sent to logic control circuit.
Step S530: filter circuit detects the voltage of current sense resistor, and produces an average voltage value signal to be sent to described application condition circuit.
Step S540: application condition circuit receives the average voltage value signal that described filter circuit produces, and compares with built-in level reference signal, and output mean value controls signal to described logic control circuit.
Step S550: the mistake flow control signals that logic control circuit receives the clock signal that described high-frequency oscillating circuits produces, described peak current detection circuit produces and the mean value control signal that described application condition circuit produces, and power output pipe control signal, to control conducting or the shutoff of described power tube, and then the electric current of the external loading be electrically connected with described control circuit is made to reach goal-selling electric current.
Furthermore, when the mean value control signal that described application condition circuit exports is high level, the electric current on the external loading be electrically connected with described control circuit is less than goal-selling electric current, and described power tube is allowed to open and charges to external loading; Or when the mean value control signal that described application condition circuit exports is low level, the electric current on the external loading be electrically connected with described control circuit is greater than goal-selling electric current, described power tube is prohibited conducting and charges to external loading.
In addition, described control circuit close current period conducting power tube or by skipping one or more clock signal period to forbid power tube conducting, make the target current that the electric current flowing through external loading equals default.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (15)
1. a control circuit, is characterized in that, comprising: a high-frequency oscillating circuits, a peak current detection circuit, a filter circuit, an application condition circuit, a logic control circuit and power tube; Wherein,
Described high-frequency oscillating circuits is electrically connected with described logic control circuit, and described high-frequency oscillating circuits is for generation of the clock signal of a fixed frequency;
Described peak current detection circuit is electrically connected with the drain electrode of described logic control circuit and described power tube respectively, described peak current detection circuit is used for the peak current that detection and control flows through described power tube, when the peak current flowing through described power tube reaches pre-set peak value electric current, output overcurrent control signal;
Described filter circuit is electrically connected with the source electrode of described power tube and the current sense resistor of outside that is electrically connected with described control circuit respectively, and described filter circuit for detecting the voltage of described current sense resistor, and produces an average voltage value signal;
Described application condition circuit is electrically connected with described filter circuit and described logic control circuit respectively, the average voltage value signal that described application condition circuit produces for receiving described filter circuit, and compare with built-in level reference signal, and export mean value control signal;
Described logic control circuit is electrically connected with the grid of described power tube, the mistake flow control signals that described logic control circuit produces for the clock signal produced that receives described high-frequency oscillating circuits, described peak current detection circuit and the mean value control signal that described application condition circuit produces, and power output pipe control signal, to control conducting or the shutoff of described power tube, and then the electric current of the external loading be electrically connected with described control circuit is made to reach goal-selling electric current.
2. control circuit according to claim 1, is characterized in that, described filter circuit is RC formula filter circuit.
3. control circuit according to claim 1, it is characterized in that, when the mean value control signal that described application condition circuit exports is high level, electric current on the external loading be electrically connected with described control circuit is less than goal-selling electric current, and described power tube is allowed to open and charges to external loading.
4. the control circuit according to claim 1 or 3, it is characterized in that, described power tube control signal becomes high level at the rising edge of described clock signal, the conducting after described power tube control signal becomes high level of described power tube, the maximum ON time of described power tube determined by the high level duty ratio of described clock signal and frequency of oscillation.
5. control circuit according to claim 1, it is characterized in that, when flowing through the pre-set peak value electric current that the electric current on described power tube reaches set by described peak current detection circuit, the mistake flow control signals that described peak current detection circuit exports becomes high level, and then described power tube is turned off after described power tube control signal becomes low level.
6. control circuit according to claim 1 or 5, it is characterized in that, when the mean value control signal that described application condition circuit exports is low level, electric current on the external loading be electrically connected with described control circuit is greater than goal-selling electric current, and described power tube is prohibited to open and charges to external loading.
7. control circuit according to claim 6, is characterized in that, described control circuit cuts out the power tube of current period conducting, makes the electric current flowing through external loading equal goal-selling electric current.
8. control circuit according to claim 6, is characterized in that, described control circuit, by skipping one or more clock signal period to forbid power tube conducting, makes the electric current flowing through external loading equal goal-selling electric current.
9. a LED drive chip, it is characterized in that, described chip comprises the control circuit described in any one in claim 1-8 item, and described LED drive chip, in order to control the electric current of the load be electrically connected with described LED drive chip, makes the electric current of described load be goal-selling electric current.
10. a LED constant current Drive and Control Circuit, it is characterized in that, comprising: an input ac voltage source, a rectifier bridge, an input capacitance, a current sense resistor, an inductance, a load, a fly-wheel diode and LED drive chip according to claim 9; The two ends in described input ac voltage source are electrically connected to the common connecting point of parallel connection two rectification branch roads of described rectifier bridge respectively; One end of described input capacitance is electrically connected to a wherein tie point of described common connecting point, and the other end of described input capacitance is electrically connected to wherein another tie point of described common connecting point;
The D pin of described LED drive chip is electrically connected to one end of described input capacitance, and the CS pin of described LED drive chip is electrically connected to one end of described current sense resistor and the negative pole of described fly-wheel diode respectively, the GND pin ground connection of described LED drive chip;
The other end of described current sense resistor is electrically connected to ground connection after described inductance and described load successively;
The positive pole of described fly-wheel diode is electrically connected to the other end of described input capacitance and ground connection simultaneously; Wherein,
Described rectifier bridge and described input capacitance are in order to change the AC-input voltage in described input ac voltage source into DC input voitage;
Described current sense resistor is in order to detect and to set the average current flowing through described load;
Described LED drive chip is in order to the voltage by gathering on described current sense resistor, and the DC input voitage controlling to change transmits energy, so that make the electric current of described load be goal-selling electric current to described inductance and described load.
11. LED constant current Drive and Control Circuit according to claim 10, it is characterized in that, when described power tube control signal becomes high level and after described power tube conducting, described DC input voitage is charged to described inductance by the power tube of described LED drive chip, described current sense resistor and described load at the rising edge of described clock signal.
12. LED constant current Drive and Control Circuit according to claim 10, it is characterized in that, the mistake flow control signals exported when described peak current detection circuit becomes high level and described power tube is closed have no progeny, and described inductance carries out afterflow by described fly-wheel diode.
13. 1 kinds of LED constant current drived control methods, adopt control circuit according to claim 1, it is characterized in that, comprise the following steps:
High-frequency oscillating circuits produces the clock signal of a fixed frequency and is sent to logic control circuit;
Peak current detection circuit detection and control flows through the peak current of power tube, and when the peak current flowing through described power tube reaches pre-set peak value electric current, described peak current detection circuit output overcurrent control signal is also sent to logic control circuit;
Filter circuit detects the voltage of current sense resistor, and produces an average voltage value signal to be sent to described application condition circuit; Application condition circuit receives the average voltage value signal that described filter circuit produces, and compares with built-in level reference signal, and output mean value controls signal to described logic control circuit;
The mistake flow control signals that described logic control circuit receives the clock signal that described high-frequency oscillating circuits produces, described peak current detection circuit produces and the mean value control signal that described application condition circuit produces, and power output pipe control signal, to control conducting or the shutoff of described power tube, and then the electric current of the external loading be electrically connected with described control circuit is made to reach goal-selling electric current.
14. LED constant current drived control methods according to claim 13, it is characterized in that, when the mean value control signal that described application condition circuit exports is high level, electric current on the external loading be electrically connected with described control circuit is less than goal-selling electric current, and described power tube is allowed to open and charges to external loading; Or when the mean value control signal that described application condition circuit exports is low level, the electric current on the external loading be electrically connected with described control circuit is greater than goal-selling electric current, described power tube is prohibited conducting and charges to external loading.
15. LED constant current drived control methods according to claim 14, described control circuit close current period conducting power tube or by skipping one or more clock signal period to forbid power tube conducting, make the electric current flowing through external loading equal goal-selling electric current.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108063609A (en) * | 2017-12-27 | 2018-05-22 | 杰华特微电子（杭州）有限公司 | A kind of frequency control circuit, control method and on-off circuit |
| CN110361590A (en) * | 2019-07-19 | 2019-10-22 | 广东浪潮大数据研究有限公司 | A kind of clock pulses wave arrangement for detecting |
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| CN108063609A (en) * | 2017-12-27 | 2018-05-22 | 杰华特微电子（杭州）有限公司 | A kind of frequency control circuit, control method and on-off circuit |
| CN108063609B (en) * | 2017-12-27 | 2024-01-23 | 杰华特微电子股份有限公司 | Frequency control circuit, control method and switching circuit |
| CN110361590A (en) * | 2019-07-19 | 2019-10-22 | 广东浪潮大数据研究有限公司 | A kind of clock pulses wave arrangement for detecting |
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