CN102740538B - Led drive circuit - Google Patents
Led drive circuit Download PDFInfo
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- CN102740538B CN102740538B CN201110092617.7A CN201110092617A CN102740538B CN 102740538 B CN102740538 B CN 102740538B CN 201110092617 A CN201110092617 A CN 201110092617A CN 102740538 B CN102740538 B CN 102740538B
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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
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/20—Responsive to malfunctions or to light source life; for protection
- H05B47/24—Circuit arrangements for protecting against overvoltage
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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]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
- H05B45/56—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits involving measures to prevent abnormal temperature of the LEDs
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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- Circuit Arrangement For Electric Light Sources In General (AREA)
- Led Devices (AREA)
Abstract
The present invention relates to an LED drive circuit which includes a micro-control unit, a voltage protection unit and an LED light source. The voltage protection unit includes an under-voltage protection module, an overvoltage protection module and a reference voltage module. The under-voltage protection module includes a detection voltage input terminal and a reference minimum voltage input terminal. The overvoltage protection module comprises a detection voltage input and a reference maximum voltage input terminal. The reference voltage module provides reference minimum voltage to the under-voltage protection module and provides reference maximum voltage to the overvoltage protection module. The under-voltage protection module and a reference voltage regulation module are set, thus when input voltage is lower than rated minimum voltage, detection voltage is lower than the reference minimum voltage, and the LED light source is turned off. The overvoltage protection module and the reference voltage regulation module, thus when the input voltage is higher than rated maximum voltage, the detection voltage is higher than the reference maximum voltage, and the LED light source is turned off. The LED drive circuit can maintain a constant current characteristic and has the protection of under-voltage, overvoltage and overheating.
Description
Technical field
The present invention relates to a kind of lighting field, particularly relate to a kind of LED drive circuit.
Background technology
Along with the development of science and technology, the characteristics such as LED, as new type light source, possesses light efficiency high, energy-efficient, and the life-span is long, and low pressure is controlled, are widely used in the indoor and outdoor lighting in each field, have also occurred various LED drive circuit thereupon.All adopt DC-DC wave chopping technology to carry out driving LED at present in the place of low-voltage, it has the advantages such as power consumption is little, efficiency is high, reliable and stable, unit power volume is little, lightweight, but its cost is high, circuit is complicated, fragile, have the shortcomings such as stronger High-frequency Interference, bring inconvenience to user.In the application, LED drive circuit needs to keep constant-current characteristics as far as possible, namely when supply voltage change, the electric current of LED drive circuit still can be kept to change in less scope.Under the prerequisite keeping constant-current characteristics, defencive function is also very important, the defencive function of such as voltage and the defencive function of temperature.
Summary of the invention
The object of the present invention is to provide a kind of LED drive circuit, when its input voltage is between specified minimum voltage to specified ceiling voltage, under the adjustment of LED drive circuit, the operating current of described LED light source can keep constant-current characteristics; When the input voltage of LED drive circuit is not between specified minimum voltage to specified ceiling voltage, LED drive circuit controls to close LED light source, avoid input voltage too small or excessive time, damage driving LED drive circuit and LED light source; When ambient temperature changes, LED drive circuit can reduce the operating current of LED light source or close LED light source, avoids the too high light decay caused of the temperature of LED light source accelerate or burn out.
Above-mentioned purpose is achieved through the following technical solutions:
A kind of LED drive circuit, comprises micro-control unit, voltage protection unit and LED light source; When the input voltage of described LED drive circuit is between specified minimum voltage to specified ceiling voltage, described LED light source normally works;
Described voltage protection unit comprises under-voltage protective module, overvoltage protective module and reference voltage Voltage stabilizing module; Described under-voltage protective module comprises detection voltage input end and benchmark minimum voltage input; Described overvoltage protective module comprises detection voltage input end and reference maximum voltage input; Described reference voltage module provides benchmark minimum voltage for under-voltage protective module and provides reference maximum voltage for overvoltage protective module;
Arrange under-voltage protective module and reference voltage Voltage stabilizing module, when making input voltage lower than specified minimum voltage, the detection voltage of under-voltage protective module is lower than benchmark minimum voltage, and under-voltage protective module controls micro-control unit makes it close LED light source;
Arrange overvoltage protective module and reference voltage Voltage stabilizing module, when making input voltage higher than specified ceiling voltage, the detection voltage of overvoltage protective module is higher than reference maximum voltage, and overvoltage protective module controls micro-control unit makes it close LED light source.
Above-mentioned purpose can also be perfect further by following technical proposals.
Described under-voltage protective module comprises the first operational amplifier, the first pull-up resistor and the first pull down resistor; First pull-up resistor one end is connected to high level, the first pull-up resistor and the series connection of the first pull down resistor, first pull down resistor one end ground connection, and the node of the first pull-up resistor and the first pull down resistor is connected to the inverting input of the first operational amplifier;
Described overvoltage protective module comprises the second operational amplifier, the second pull-up resistor and the second pull down resistor; Second pull-up resistor one end is connected to high level, the second pull-up resistor and the series connection of the second pull down resistor, second pull down resistor one end ground connection, and the node of the second pull-up resistor and the second pull down resistor is connected to the in-phase input end of the second operational amplifier;
Described reference voltage Voltage stabilizing module comprises the first current-limiting resistance and reference voltage voltage stabilizing chip; First current-limiting resistance one end is connected to high level, the first current-limiting resistance and reference voltage voltage stabilizing chip-in series, reference voltage voltage stabilizing chip one end ground connection; The node of the first current-limiting resistance and reference voltage voltage stabilizing chip is connected to the in-phase input end of the first operational amplifier and the inverting input of the second operational amplifier;
The output of described first operational amplifier and the output of the second operational amplifier are connected to the voltage protection input port of micro-control unit; The positive power source terminal of described first operational amplifier and the positive power source terminal of the second operational amplifier are connected respectively to high level, the negative power end of described first operational amplifier and the negative power end of the second operational amplifier ground connection respectively.
Beneficial effect of the present invention:
When the input voltage of LED drive circuit of the present invention is between specified minimum voltage to specified ceiling voltage, under the adjustment of LED drive circuit, the operating current of described LED light source can keep constant-current characteristics; When the input voltage of LED drive circuit is not between specified minimum voltage to specified ceiling voltage, LED drive circuit controls to close LED light source, avoid input voltage too small or excessive time, damage driving LED drive circuit and LED light source; When ambient temperature changes, LED drive circuit can reduce the operating current of LED light source or close LED light source, avoids the too high light decay caused of the temperature of LED light source accelerate or burn out.
Accompanying drawing explanation
Fig. 1 is the structural representation of LED drive circuit of the present invention;
Fig. 2 is the circuit theory diagrams of LED drive circuit of the present invention;
Wherein:
101 first operational amplifiers (symbol U2A), 102 first pull-up resistors (symbol R2), 103 first pull down resistors (symbol R3);
201 second operational amplifiers (symbol U2B), 202 second pull-up resistors (symbol R4), 203 second pull down resistors (symbol R5), 204 second filter capacitors (symbol C2), 205 first counnter attack diodes (symbol D1), 206 second counnter attack diodes (symbol D2);
301 first current-limiting resistances (symbol R1), 302 reference voltage voltage stabilizing chips (symbol U3);
401 negative tempperature coefficient thermistors (symbol RT1), 402 divider resistances (symbol R6);
501 drive triode (symbol Q2), 502 second current-limiting resistances (symbol R11), 503 the 3rd pull down resistors (symbol R12), 504 the 3rd current-limiting resistances (symbol R10), 505 switch triodes (symbol Q1), 506 the 3rd pull-up resistors (symbol R9), 507 fly-wheel diodes (symbol D3), 508 afterflow inductance (symbol L1), 509 first filter capacitors (symbol C3), 510 current sampling resistors (symbol R13);
601 the 4th pull-up resistors (symbol R8), 602 switches (symbol K1);
701 single-chip microcomputers (symbol U1);
Filtering and storage source electric capacity (symbol C1); Rectifier bridge stack (symbol D4); LED1, LED2, LED3 LED light source.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, LED drive circuit of the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
LED drive circuit of the present invention, as shown in Figure 1, comprises micro-control unit (Micro Control Unit is called for short MCU), voltage protection unit and LED light source; When the input voltage of described LED drive circuit is between specified minimum voltage to specified ceiling voltage, described LED light source normally works; If specified minimum voltage is 11 volts, specified ceiling voltage is 30 volts;
Described voltage protection unit comprises under-voltage protective module, overvoltage protective module and reference voltage Voltage stabilizing module; Described under-voltage protective module comprises detection voltage input end and benchmark minimum voltage input; Described overvoltage protective module comprises detection voltage input end and reference maximum voltage input; Described reference voltage module provides benchmark minimum voltage for under-voltage protective module and provides reference maximum voltage for overvoltage protective module;
Arrange under-voltage protective module and reference voltage Voltage stabilizing module, when making input voltage lower than specified minimum voltage, the detection voltage of under-voltage protective module is lower than benchmark minimum voltage, and under-voltage protective module controls micro-control unit makes it close LED light source;
Arrange overvoltage protective module and reference voltage Voltage stabilizing module, when making input voltage higher than specified ceiling voltage, the detection voltage of overvoltage protective module is higher than reference maximum voltage, and overvoltage protective module controls micro-control unit makes it close LED light source.
Wherein, pulse width modulation (Pulse Width Modulation, be called for short PWM) ripple, be utilize the numeral of micro-control unit to export the very effective technology of one controlled analog circuit, be widely used in and control with many fields of conversion from measurement, the power that communicates.
As shown in Figure 2, described under-voltage protective module comprises the first operational amplifier 101 (symbol U2A), the first pull-up resistor 102 (symbol R2) and the first pull down resistor 103 (symbol R3); First pull-up resistor 102 (symbol R2) one end is connected to high level, first pull-up resistor 102 (symbol R2) and the series connection of the first pull down resistor 103 (symbol R3), first pull down resistor 103 (symbol R3) one end ground connection, the node of the first pull-up resistor 102 (symbol R2) and the first pull down resistor 103 (symbol R3) is connected to the inverting input (symbol pin 2) of the first operational amplifier 101 (symbol U2A);
Described overvoltage protective module comprises the second operational amplifier 201 (symbol U2B), the second pull-up resistor 202 (symbol R4) and the second pull down resistor 203 (symbol R5); Second pull-up resistor 202 (symbol R4) one end is connected to high level, second pull-up resistor 202 (symbol R4) and the series connection of the second pull down resistor 203 (symbol R5), second pull down resistor 203 (symbol R5) one end ground connection, the node of the second pull-up resistor 202 (symbol R4) and the second pull down resistor 203 (symbol R5) is connected to the in-phase input end (symbol pin 5) of the second operational amplifier 201 (symbol U2B);
Described reference voltage Voltage stabilizing module comprises the first current-limiting resistance 301 (symbol R1) and reference voltage voltage stabilizing chip 302 (symbol U3); First current-limiting resistance 301 (symbol R1) one end is connected to high level, first current-limiting resistance 301 (symbol R1) and reference voltage voltage stabilizing chip 302 (symbol U3) series connection, reference voltage voltage stabilizing chip 302 (symbol U3) one end ground connection; The node of the first current-limiting resistance 301 (symbol R1) and reference voltage voltage stabilizing chip 302 (symbol U3) is connected to the in-phase input end (symbol pin 3) of the first current-limiting resistance 301 (symbol R1) and the inverting input (symbol pin 6) of the second operational amplifier 201 (symbol U2B);
The output (symbol pin 1) of described first operational amplifier 101 (symbol U2A) and the output (symbol pin 7) of the second operational amplifier 201 (symbol U2B) are connected to the voltage protection input port (symbol PB2) of micro-control unit; The positive power source terminal (symbol pin 8) of described first operational amplifier 101 (symbol U2A) and the positive power source terminal (symbol pin 8) of the second operational amplifier 201 (symbol U2B) are connected respectively to high level, the negative power end (symbol pin 4) of described first operational amplifier 101 (symbol U2A) and the negative power end (symbol pin 4) of the second operational amplifier 201 (symbol U2B) ground connection respectively.
Under-voltage protective module and reference voltage Voltage stabilizing module are set, make input voltage lower than (when input voltage is lower than 11 volts) during specified minimum voltage, the voltage (i.e. the detection voltage of under-voltage protective module) of the inverting input (symbol pin 2) of described first operational amplifier 101 (symbol U2A) is lower than the voltage (i.e. benchmark minimum voltage) of its in-phase input end (symbol pin 3); The output (symbol pin 1) of described first operational amplifier 101 (symbol U2A) exports high level, and micro-control unit is closed to constant current driving unit output pulse width modulating wave and then closed LED light source (namely micro-control unit closes LED light source);
Overvoltage protective module and reference voltage Voltage stabilizing module are set, make input voltage higher than (when input voltage is higher than 30 volts) during specified ceiling voltage, the voltage (i.e. the detection voltage of overvoltage protective module) of the in-phase input end (symbol pin 5) of described second operational amplifier 201 (symbol U2B) is higher than the voltage (i.e. reference maximum voltage) of its inverting input (symbol pin 6); The output (symbol pin 7) of described second operational amplifier 201 (symbol U2B) exports high level, and micro-control unit is closed to constant current driving unit output pulse width modulating wave and then closed LED light source (namely micro-control unit closes LED light source).
As shown in Figure 2, LED drive circuit also comprises overtemperature protection unit, and described overtemperature protection unit comprises negative tempperature coefficient thermistor 401 (symbol RT1) and divider resistance 402 (symbol R6); Negative tempperature coefficient thermistor 401 (symbol RT1) is connected to high level, negative tempperature coefficient thermistor 401 (symbol RT1) and divider resistance 402 (symbol R6) series connection, divider resistance 402 (symbol R6) ground connection; Node between negative tempperature coefficient thermistor 401 (symbol RT1) and divider resistance 402 (symbol R6) is connected to the overtemperature protection input port (symbol PB1) of micro-control unit.
Wherein, negative tempperature coefficient thermistor 401 (symbol RT1) reduces along with temperature raises resistance.
Electric current when described micro-control unit works according to LED light source, arranges the upper limit and the maximum operating currenbt of the running current of LED light source;
The operating current of described overtemperature protection unit be greater than running current upper in limited time, the pulse width modulation wave that micro-control unit controls exports to constant current driving unit and then the electric current turning LED light source down;
When the operating current of described overtemperature protection unit is greater than maximum operating currenbt, micro-control unit is closed to constant current driving unit output pulse width modulating wave and then is closed LED light source.
Wherein, electric current when LED light source normally works is a scope, this scope is set to the running current of LED light source; The maximum current that LED light source can bear is set to the maximum operating currenbt of LED light source.
As shown in Figure 2, described constant current driving unit comprises driving triode 501 (symbol Q2), second current-limiting resistance 502 (symbol R11), 3rd pull down resistor 503 (symbol R12), 3rd current-limiting resistance 504 (symbol R10), switch triode 505 (symbol Q1), 3rd pull-up resistor 506 (symbol R9), fly-wheel diode 507 (symbol D3), afterflow inductance 508 (symbol L1), the first filter capacitor 509 (symbol C3) and current sampling resistor 510 (symbol R13);
The base stage of described driving triode 501 (symbol Q2) is connected with the pulse width modulation wave delivery outlet (symbol PB3) of micro-control unit by the second current-limiting resistance 502 (symbol R11);
The grounded emitter of described driving triode 501 (symbol Q2), connects between its emitter with base stage, the 3rd pull down resistor 503 (symbol R12);
The collector electrode of described driving triode 501 (symbol Q2) is connected with the base stage of switch triode 505 (symbol Q1) by the 3rd current-limiting resistance 504 (symbol R10);
The emitter of described switch triode 501 (symbol Q2) is connected to high level, the 3rd pull-up resistor 506 (symbol R9) of connecting between the base stage of described switch triode 505 (symbol Q1) and emitter;
The collector electrode of described switch triode 505 (symbol Q1) is by fly-wheel diode 507 (symbol D3) ground connection, and the collector electrode of described switch triode 505 (symbol Q1) is by afterflow inductance 508 (symbol L1) and the first filter capacitor 509 (symbol C3) ground connection; The node of afterflow inductance 508 (symbol L1) and the first filter capacitor 509 (symbol C3) is by LED light source and current sampling resistor 510 (symbol R13) ground connection;
The node of described LED light source and current sampling resistor 510 (symbol R13) is connected to the sample rate current input port (symbol PB4) of micro-control unit.
Preferably, LED drive circuit also comprises control unit, and described control unit comprises the 4th pull-up resistor 601 (symbol R8) and switch 602 (symbol K1); 4th pull-up resistor 601 (symbol R8) is connected to high level, the 4th pull-up resistor 601 (symbol R8) and switch 602 (symbol K1) series connection, switch 602 (symbol K1) ground connection; The node of the 4th pull-up resistor 601 (symbol R8) and switch is connected to the power supply signal input port (symbol PB0) of micro-control unit; The switching signal that described micro-control unit produces according to switch 602 (symbol K1), by described constant current driving unit, voltage protection unit and overtemperature protection unit controls LED light source.
Preferably, described micro-control unit is single-chip microcomputer 701 (symbol U1); Described single-chip microcomputer 701 (symbol U1) is according to the switching signal of power supply signal input port (symbol PB0), by pulse width modulation wave delivery outlet (symbol PB3) to constant current driving unit output pulse width modulating wave, make LED light source work; Again sample rate current input port (symbol PB4) operating current to LED light source is sampled; The running current of the LED light source that the operating current of LED light source and single-chip microcomputer U1 are arranged compares by single-chip microcomputer 701 (symbol U1), according to the output pulse width modulating wave of comparative result adjustment pulse width modulation wave delivery outlet (symbol PB3), and then the operating current of adjustment LED light source, thus reach the object of constant current.
Preferably, the node of described second pull-up resistor 202 (symbol R4) and the second pull down resistor 203 (symbol R5) is by the second filter capacitor 204 (symbol C2) ground connection.
Preferably, the output (symbol pin 1) of described first operational amplifier 101 (symbol U2A) is connected to the voltage protection input port (symbol PB2) of micro-control unit by the first counnter attack diode 205 (symbol D1).
The output (symbol pin 7) of described second operational amplifier 201 (symbol U2B) is connected to the voltage protection input port (symbol PB2) of micro-control unit by the second counnter attack diode 206 (symbol D2).
Preferably, input voltage is by two input pole (symbol 1 and 3) inputs of rectifier bridge stack (symbol D4), the positive pole (symbol 2) of rectifier bridge stack (symbol D4) exports high level, negative pole (symbol 4) ground connection of rectifier bridge stack (symbol D4).
When the input voltage of LED drive circuit of the present invention is between specified minimum voltage to specified ceiling voltage, under the adjustment of LED drive circuit, the operating current of described LED light source can keep constant-current characteristics; When the input voltage of LED drive circuit is not between specified minimum voltage to specified ceiling voltage, LED drive circuit controls to close LED light source, avoid input voltage too small or excessive time, damage driving LED drive circuit and LED light source; When ambient temperature changes, LED drive circuit can reduce the operating current of LED light source or close LED light source, avoids the too high light decay caused of the temperature of LED light source accelerate or burn out.
Finally it should be noted that obviously, those skilled in the art can carry out various change and modification to the present invention and not depart from the spirit and scope of the present invention.Like this, if these amendments of the present invention and modification belong within the scope of the claims in the present invention and equivalent technologies thereof, then the present invention is also intended to comprise these change and modification.
Claims (8)
1. a LED drive circuit, is characterized in that:
Comprise micro-control unit, voltage protection unit and LED light source; When the input voltage of described LED drive circuit is between specified minimum voltage to specified ceiling voltage, described LED light source normally works;
Described voltage protection unit comprises under-voltage protective module, overvoltage protective module and reference voltage Voltage stabilizing module; Described under-voltage protective module comprises detection voltage input end and benchmark minimum voltage input; Described overvoltage protective module comprises detection voltage input end and reference maximum voltage input; Described reference voltage module provides benchmark minimum voltage for under-voltage protective module and provides reference maximum voltage for overvoltage protective module;
Arrange under-voltage protective module and reference voltage Voltage stabilizing module, when making input voltage lower than specified minimum voltage, the detection voltage of under-voltage protective module is lower than benchmark minimum voltage, and under-voltage protective module controls micro-control unit makes it close LED light source;
Arrange overvoltage protective module and reference voltage Voltage stabilizing module, when making input voltage higher than specified ceiling voltage, the detection voltage of overvoltage protective module is higher than reference maximum voltage, and overvoltage protective module controls micro-control unit makes it close LED light source; Described specified minimum voltage is 11 volts, and described specified ceiling voltage is 30 volts; And
Constant current driving unit, described constant current driving unit comprises driving triode (501), second current-limiting resistance (502), 3rd pull down resistor (503), the 3rd current-limiting resistance (504), switch triode (505), 3rd pull-up resistor (506), fly-wheel diode (507), afterflow inductance (508), the first filter capacitor (509) and current sampling resistor (510);
The base stage of described driving triode (501) is connected with the pulse width modulation wave delivery outlet of micro-control unit by the second current-limiting resistance (502);
The grounded emitter of described driving triode (501), the 3rd pull down resistor (503) of connecting between its emitter with base stage;
The collector electrode of described driving triode (501) is connected with the base stage of switch triode (505) by the 3rd current-limiting resistance (504);
The emitter of described switch triode (505) is connected to high level, the 3rd pull-up resistor (506) of connecting between the base stage of described switch triode (505) and emitter;
The collector electrode of described switch triode (505) is by fly-wheel diode (507) ground connection, and the collector electrode of described switch triode (505) is by afterflow inductance (508) and the first filter capacitor (509) ground connection; The node of described afterflow inductance (508) and the first filter capacitor (509) is by LED light source and current sampling resistor (510) ground connection;
The node of described LED light source and current sampling resistor (510) is connected to the sample rate current input port of micro-control unit;
Also comprise overtemperature protection unit, described overtemperature protection unit comprises negative tempperature coefficient thermistor (401) and divider resistance (402); Negative tempperature coefficient thermistor (401) is connected to high level, negative tempperature coefficient thermistor (401) and divider resistance (402) series connection, divider resistance (402) ground connection; Node between negative tempperature coefficient thermistor (401) and divider resistance (402) is connected to the overtemperature protection input port of micro-control unit.
2. LED drive circuit according to claim 1, is characterized in that:
Described under-voltage protective module comprises the first operational amplifier (101), the first pull-up resistor (102) and the first pull down resistor (103); First pull-up resistor (102) one end is connected to high level, first pull-up resistor (102) and the first pull down resistor (103) series connection, first pull down resistor (103) one end ground connection, the node of the first pull-up resistor (102) and the first pull down resistor (103) is connected to the inverting input of the first operational amplifier (101);
Described overvoltage protective module comprises the second operational amplifier (201), the second pull-up resistor (202) and the second pull down resistor (203); Second pull-up resistor (202) one end is connected to high level, second pull-up resistor (202) and the second pull down resistor (203) series connection, second pull down resistor (203) one end ground connection, the node of the second pull-up resistor (202) and the second pull down resistor (203) is connected to the in-phase input end of the second operational amplifier (201);
Described reference voltage Voltage stabilizing module comprises the first current-limiting resistance (301) and reference voltage voltage stabilizing chip (302); First current-limiting resistance (301) one end is connected to high level, the first current-limiting resistance (301) and reference voltage voltage stabilizing chip (302) series connection, reference voltage voltage stabilizing chip (302) one end ground connection; The node of the first current-limiting resistance (301) and reference voltage voltage stabilizing chip (302) is connected to the in-phase input end of the first operational amplifier (101) and the inverting input of the second operational amplifier (201);
The output of described first operational amplifier (101) and the output of the second operational amplifier (201) are connected to the voltage protection input port of micro-control unit; The positive power source terminal of described first operational amplifier (101) and the positive power source terminal of the second operational amplifier (201) are connected respectively to high level, the negative power end of described first operational amplifier (101) and the negative power end of the second operational amplifier (201) ground connection respectively.
3. LED drive circuit according to claim 1, is characterized in that:
Also comprise control unit, described control unit comprises the 4th pull-up resistor (601) and switch (602); 4th pull-up resistor (601) is connected to high level, the 4th pull-up resistor (601) and switch (602) series connection, switch (602) ground connection; The node of the 4th pull-up resistor (601) and switch (602) is connected to the power supply signal input port of micro-control unit; The switching signal that described micro-control unit produces according to switch (602), by described constant current driving unit, voltage protection unit and overtemperature protection unit controls LED light source.
4. LED drive circuit according to claim 2, is characterized in that:
Arrange under-voltage protective module and reference voltage Voltage stabilizing module, when making input voltage lower than specified minimum voltage, the voltage of the inverting input of described first operational amplifier (101) is lower than the voltage of its in-phase input end; The output of described first operational amplifier (101) exports high level, and micro-control unit closes LED light source;
Arrange overvoltage protective module and reference voltage Voltage stabilizing module, when making input voltage higher than specified ceiling voltage, the voltage of the in-phase input end of described second operational amplifier (201) is higher than the voltage of its inverting input; The output of described second operational amplifier (201) exports high level, and micro-control unit closes LED light source.
5. LED drive circuit according to claim 1, is characterized in that:
Electric current when described micro-control unit normally works according to LED light source, the upper limit of the running current of setting and maximum operating currenbt;
The operating current of described overtemperature protection unit be greater than running current upper in limited time, the pulse width modulation wave that micro-control unit controls exports to constant current driving unit and then the electric current turning LED light source down;
When the operating current of described overtemperature protection unit is greater than maximum operating currenbt, micro-control unit is closed to constant current driving unit output pulse width modulating wave and then is closed LED light source.
6. LED drive circuit according to claim 3, is characterized in that:
Described micro-control unit is single-chip microcomputer (701); Described single-chip microcomputer (701), according to the switching signal of power supply signal input port, by pulse width modulation wave delivery outlet to constant current driving unit output pulse width modulating wave, makes LED light source work; Sampled to the operating current of LED light source in sample rate current input port again; The running current of the LED light source that the operating current of LED light source and single-chip microcomputer (701) are arranged compares by single-chip microcomputer (701), according to the output pulse width modulating wave of comparative result adjustment pulse width modulation wave delivery outlet, and then the operating current of adjustment LED light source.
7. LED drive circuit according to claim 2, is characterized in that:
The node of described second pull-up resistor (202) and the second pull down resistor (203) is by the second filter capacitor (204) ground connection.
8. LED drive circuit according to claim 2, is characterized in that:
The output of described first operational amplifier (101) is connected to the voltage protection input port of micro-control unit by the first counnter attack diode (205);
The output of described second operational amplifier (201) is connected to the voltage protection input port of micro-control unit by the second counnter attack diode (206).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110092617.7A CN102740538B (en) | 2011-04-13 | 2011-04-13 | Led drive circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201110092617.7A CN102740538B (en) | 2011-04-13 | 2011-04-13 | Led drive circuit |
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| CN102740538A CN102740538A (en) | 2012-10-17 |
| CN102740538B true CN102740538B (en) | 2015-03-11 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3537851A4 (en) * | 2017-06-27 | 2020-06-10 | Shenzhen Chuangwei-RGB Electronic Co., Ltd. | Led light bar network current foldback circuit, driving power supply and tv set |
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