CN103220857B - A kind of LED constant-current control circuit - Google Patents
A kind of LED constant-current control circuit Download PDFInfo
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- CN103220857B CN103220857B CN201310123703.9A CN201310123703A CN103220857B CN 103220857 B CN103220857 B CN 103220857B CN 201310123703 A CN201310123703 A CN 201310123703A CN 103220857 B CN103220857 B CN 103220857B
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Abstract
The invention provides a kind of LED constant-current control circuit, this LED constant-current control circuit comprises power input port, load outputs mouth, detection port and constant-current control module, detection port is between power input port and load outputs mouth, constant-current control module comprises Master control chip and detection signal amplification module, Master control chip is connected electrically between power input port and load outputs mouth, detection signal amplification module is connected electrically between the comparison port of detection port and Master control chip, with by the electrical signal transfer at detection port place to comparing port, wherein, the signal of telecommunication collected can be amplified different multiples by detection signal amplification module, the signal of telecommunication of the different amplification exported according to detection signal amplification module to enable Master control chip and export the electric current of different size respectively.LED constant-current control circuit can make the LED of the load end being connected to LED constant-current control circuit can send the light of different brightness.
Description
Technical field
The present invention relates to integrated circuit, particularly, relate to a kind of LED constant-current control circuit.
Background technology
LED is a kind of display device of function admirable, has that life-span long, economize on electricity, brightness are high, an advantage such as at the bottom of fast response time and driving voltage.LED has all been employed as illumination component in a lot of equipment.Such as, in vehicle, the lighting apparatus such as headlight, position lamp, daytime running lamps all employ LED.But in the prior art, above-mentioned lighting apparatus is mutual independently LED, and each lighting apparatus needs a set of drive circuit corresponding with it, larger installing space is therefore needed to establish and corresponding drive circuit to install described illumination.
Therefore, the use number how reducing LED under the prerequisite of assurance function becomes this area technical problem urgently to be resolved hurrily.
Summary of the invention
The object of the present invention is to provide a kind of LED constant-current control circuit, this LED constant-current control circuit can export the electric current varied in size, thus the LED of the load end being connected to described LED constant-current control circuit can be made can to send the light of different brightness.
To achieve these goals, a kind of LED constant-current control circuit of the present invention, this LED constant-current control circuit comprises power input port, load outputs mouth, detection port and constant-current control module, described detection port is between described power input port and described load outputs mouth, described constant-current control module comprises Master control chip and detection signal amplification module, described Master control chip is connected electrically between described power input port and described load outputs mouth, described detection signal amplification module is connected electrically between the comparison port of described detection port and described Master control chip, so that the electrical signal transfer at described detection port place is compared port to described, wherein, the signal of telecommunication collected can be amplified different multiples by described detection signal amplification module, the signal of telecommunication of the different amplification exported according to described detection signal amplification module to enable described Master control chip and export the electric current of different size respectively.
Preferably, detection signal amplification module comprises the first operational amplifier, the first resistance, the second resistance, the first switch element, described first resistance and described first switch elements in series are at the reverse input end of described first operational amplifier, described second resistance is in parallel with described first resistance and described first switch element, the positive input of described first operational amplifier is electrically connected with described detection port, one end ground connection of described first switch element.
Preferably, described detection signal amplification module also comprises control power supply, and this control power supply is electrically connected with described first switch element, to control switching on and off of described first switch element.
Preferably, described first switch element is triode, and the base stage of described first switch element is connected with described control power electric, and collector electrode and described first resistance of described first switch element electrically connect, the grounded emitter of described first switch element.
Preferably, described LED constant-current control circuit also comprises the first protection diode, and the positive pole of this first protection diode is electrically connected with the described port that compares, and the negative pole of described first protection diode is electrically connected with the output of described detection signal amplification module.
Preferably, described LED constant-current control circuit also comprises input reverse-connection protection module, and this input reverse-connection protection module is connected to described power input port place, described LED constant-current control circuit to be disconnected when electric current is reverse.
Preferably, described input reverse-connection protection module comprises second switch element and the first voltage-stabiliser tube, between the positive pole that described second switch element is connected on described power input port and negative pole, described second switch element is metal-oxide-semiconductor, the described drain electrode of second switch element is connected with the negative electricity of power input port, the grid of described second switch element is electrically connected with the positive pole of described power input port, the source electrode of described second switch element is electrically connected with the positive pole of described first voltage-stabiliser tube, when positive pole and the negative pole reversal connection of described power input port, described second switch element disconnects, voltage is held by the first voltage-stabiliser tube.
Preferably, described Master control chip is provided with the switch pin controlling the energising of described Master control chip or power-off, when described switch pin is in high level, described Master control chip energising, when the switch pin of described Master control chip is in low level, described Master control chip power-off.
Preferably; described LED constant-current control circuit also comprises input undervoltage protection module; described input undervoltage protection module is connected between described power input port and described switch pin, with described power input port input voltage lower than during the first reference voltage to described switch pin output low level.
Preferably; described input undervoltage protection module comprises the second operational amplifier and the 3rd switch element; described second operational amplifier can compare the input voltage of described power input port and described first reference voltage; when the input voltage of described power input port is lower than described first reference voltage; described second operational amplifier exports high level to described 3rd switch element, and described 3rd switch element is to described switch pin output low level.
Preferably, described 3rd switch element is metal-oxide-semiconductor, and the grid of described 3rd switch element is electrically connected with the output of described second operational amplifier, and the drain electrode of described 3rd switch element is electrically connected with described switch pin, the source ground of described 3rd switch element.
Preferably; described input undervoltage protection module also comprises the 3rd operational amplifier; the positive input of the 3rd operational amplifier is electrically connected with described power input port; the output of described 3rd operational amplifier is electrically connected with the positive input of described second operational amplifier, being that described first reference voltage is applied to described second operational amplifier by the voltage transitions of described power input port.
Preferably; described LED constant-current control circuit also comprises input overvoltage protective module; described input overvoltage protective module is connected between described power input port and described switch pin, with described power input port input voltage higher than during the second reference voltage to described switch pin output low level.
Preferably; described input overvoltage protective module comprises four-operational amplifier and the 4th switch element; described four-operational amplifier can compare the input voltage of described power input port and described second reference voltage; when the input voltage of described power input port is higher than described second reference voltage; described four-operational amplifier is to described 4th switch element output low level; and by described 4th switching elements conductive, thus to described switch pin output low level.
Preferably, described 4th switch element is diode, and the negative pole of described 4th switch element is electrically connected with the output of described four-operational amplifier, and the positive pole of described 4th switch element is electrically connected with described switch pin.
Preferably; described input overvoltage protective module also comprises the 5th operational amplifier; the positive input of the 5th operational amplifier is electrically connected with described power input port; the output of described 5th operational amplifier is electrically connected with the positive input of described four-operational amplifier, being that described second reference voltage is applied to described four-operational amplifier by the voltage transitions of described power input port.
Preferably; described LED constant-current control circuit also comprises output over-voltage protection module; described output over-voltage protection model calling between described load outputs mouth and described switch pin, with described load outputs mouth voltage higher than during the 3rd reference voltage to described switch pin output low level.
Preferably; described output over-voltage protection module comprises the 6th operational amplifier and the 5th switch element; the positive input of described 6th operational amplifier is applied with the 3rd reference voltage; described 6th operational amplifier can compare the output voltage of described load outputs mouth and described 3rd reference voltage; when the output voltage of described load outputs mouth is higher than described 3rd reference voltage; described 6th operational amplifier is to described 5th switch element output low level; and by described 5th switching elements conductive, thus to described switch pin output low level.
Preferably, described 5th switch element is diode, the positive pole of described 5th switch element is electrically connected with described switch pin, and the negative pole of described 5th switch element is connected with the output of described 6th operational amplifier, and the positive pole of described 5th switch element is electrically connected with described power input port.
In LED constant-current control circuit provided by the present invention, according to detection signal amplification module, detection signal can be amplified different multiples, described Master control chip exports the electric current of different size according to the multiplication factor of described detection signal, thus LED can be made to send the light of varying strength.
Accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for specification, is used from explanation the present invention, but is not construed as limiting the invention with embodiment one below.In the accompanying drawings:
Fig. 1 is the schematic diagram of a part for LED constant-current control circuit provided by the present invention;
Fig. 2 is the schematic diagram of the detection signal amplification module of LED constant-current control circuit provided by the present invention;
Fig. 3 is the schematic diagram of the input undervoltage protection module of LED constant-current control circuit provided by the present invention;
Fig. 4 is the schematic diagram of the input overvoltage protective module of LED constant-current control circuit provided by the present invention;
Fig. 5 is the schematic diagram of the output over-voltage protection module of LED constant-current control circuit provided by the present invention.
Description of reference numerals
10: power input port 20: load outputs mouth
30: detection port 41: Master control chip
42: detection signal amplification module 411: compare port
412: switch pin 421: the first operational amplifier
422: the first resistance 423: the second resistance
424: the first switch elements 425: control power supply
50: the first protection diodes 60: input reverse-connection protection module
61: second switch element 62: the first voltage-stabiliser tube
70: input undervoltage protection module 71: the second operational amplifier
72: the three switch element 73: the three operational amplifiers
74: the second protection diodes 80: input overvoltage protective module
81: the four-operational amplifier 82: the four switch elements
83: the five operational amplifiers 90: output over-voltage protection module
91: the six operational amplifier 92: the five switch elements
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.
In the present invention, " ground connection " not refers to and is connected greatly really, but is connected with the ground of IC interior, relatively low at this place's current potential.
As depicted in figs. 1 and 2, the invention provides a kind of LED constant-current control circuit, this LED constant-current control circuit comprises power input port 10, load outputs mouth 20, detection port 30 and constant-current control module, detection port 30 is between power input port 10 and load outputs mouth 20, described constant-current control module comprises Master control chip 41 and detection signal amplification module 42, Master control chip 41 is connected electrically between power input port 10 and load outputs mouth 20, detection signal amplification module 42 is connected electrically between the comparison port 411 of detection port 30 and Master control chip 41, with by the electrical signal transfer at detection port 30 place to comparing port 411, wherein, the signal of telecommunication collected can be amplified different multiples by detection signal amplification module 42, with the electric current making Master control chip 41 can export different size respectively according to the signal of telecommunication of the different amplification of described detection signal amplification module 42 output.
Foreign current inputs described LED constant-current control circuit from power input port 10, and the electric current that electric current converts required size to by the Master control chip 41 of described constant-current control module is delivered to load outputs mouth 20.In the process, by detection port 30 to Master control chip 41 fed-back current signals.The current signal collected due to detection port 30 place is less, therefore needs to feed back to Master control chip 41 again after detection signal amplification module 42 amplifies.Master control chip 41 by compare that feedback current that port 411 receives and the input port of Master control chip 41 receive from power input port 10 input current compared with, the output current of adjustment Master control chip 41, thus the electric current that can ensure to output to load outputs mouth 20 is constant current.
In the present invention, the current signal feeding back to Master control chip 41 can be amplified different multiples according to different needs by detection signal amplification module 42.The Current adjustment being input to Master control chip 41 from power input port 10 becomes the output current of different size to export to load outputs mouth 20 according to the fed-back current signals of different amplification by Master control chip 41, thus the LED being connected on load outputs mouth 20 can be made to send the light of varying strength.
Different control signals can be inputted to detection signal amplification module 42 artificially, thus make the multiple that detection signal amplification module 42 can be different by the Current amplifier collected from detection port 30.
Introduce a kind of preferred implementation of detection signal amplification module 42 below.As shown in Figure 2, detection signal amplification module 42 comprises the first operational amplifier 421, first resistance 422, second resistance 423, first switch element 424, first resistance 422 and the first switch element 424 are connected on the reverse input end of the first operational amplifier 421, second resistance 423 is in parallel with the first resistance 422 and the first switch element 424, the positive input of the first operational amplifier 421 is electrically connected with detection port 30, one end ground connection of the first switch element 424.
When the first switch element 424 disconnects, by the electric current of the reverse input end of the first operational amplifier 421 by means of only the second resistance 423, now, the signal of telecommunication inputted from detection port 30 is amplified to the first multiplication factor by the first operational amplifier 421, is then delivered to the comparison port 411 of Master control chip 41.Master control chip 41, by being exaggerated the feedback signal of the first multiplication factor compared with the input current of power input port 10, exports the first continuous current.
When the first switch element 424 is connected, the second resistance 423 and the first resistance 422 is passed through by the electric current of the reverse input end of the first operational amplifier 421, now, the signal of telecommunication inputted from detection port 30 is amplified to the second multiplication factor by the first operational amplifier 421, is then delivered to the comparison port 411 of Master control chip 41.Master control chip 41, by being exaggerated the feedback signal of the second multiplication factor compared with the input current of power input port 10, exports the second continuous current.
The size of the first continuous current and varying in size of the second continuous current, therefore, under the first switch element 424 is connected and the first switch element 424 disconnects two states, the LED being connected on load outputs mouth 20 place can send the different electric current of two kinds of intensity.
The LED gone out due to the load outputs mouth 20 being connected on LED constant-current control circuit of the present invention can send the different electric current of two kinds of intensity, and therefore, same LED can realize two kinds of different functions.Such as, when LED constant-current control circuit of the present invention is applied on automobile, same LED can be used as side-marker lamp and the daytime running lamps of automobile simultaneously.
Although only disclose the situation making same LED send the light of two kinds of varying strengths in above-mentioned preferred implementation, but, those skilled in the art should be understood that, the first switch element 424 and the first resistance 422 can be organized in the direction input parallel connection of the first operational amplifier 421 more, the signal of telecommunication that detection port 30 inputs can be zoomed into more kinds of different multiple to make the first operational amplifier 421.For this area staff, this is very easy to realize, and do not repeat them here.
For the ease of controlling switching on and off of the first switch element 424, preferably, detection signal amplification module 42 can also comprise control power supply 425, and this control power supply 425 is electrically connected with the first switch element 424, to control switching on and off of the first switch element 424.
Such as, the first switch element 424 can be connected when control power supply 425 is powered to the first switch element 424, otherwise then make the first switch element 424 disconnect.
In the present invention, the concrete structure of the first switch element 424 is not restricted.Such as, the first switch element can be triode, also can be metal-oxide-semiconductor, or also can be other any switch elements that can realize above-mentioned functions.In preferred implementation in fig. 2, first switch element 424 is triode, the base stage of the first switch element 424 is electrically connected with control power supply 425, and collector electrode and first resistance 422 of the first switch element 424 electrically connect, the grounded emitter of the first switch element 424.When controlling power supply 425 and providing high level to the base stage of the first switch element 424, the first switch element 424 conducting, thus can make by the electric current of the reverse input end of the first operational amplifier 421 through the first resistance 422 and the second resistance 423.When controlling power supply 425 and not providing high level to the base stage of the first switch element 424, the first switch element 424 not conducting, thus can make by the electric current of the reverse input end of the first operational amplifier 421 merely through the second resistance 423.
When LED constant-current control circuit of the present invention is applied to automobile, the button controlling described control power supply 425 can be set at automobile cab.When pressing the button, control power supply 425 and send control signal to the first switch element 424, when not touching the button, control power supply 425 and do not send control signal to the first switch element 424.
In order to protect Master control chip 41; preferably; this LED constant-current control circuit can also comprise the first protection diode 50, the positive pole of this first protection diode 50 with compare port 411 and be electrically connected, first protects the negative pole of diode 50 to be electrically connected with the output of detection signal amplification module 42.If LED constant-current control circuit breaks down, the current signal causing detection port 30 to collect is larger, so this larger current signal can be amplified to larger by the first operational amplifier 421, and this larger current signal is fed back to Master control chip 41 may be burnt Master control chip 41.The generation of this situation can be prevented after first protection diode 50 is set.This is because; once the current potential of the first operational amplifier 421 output is higher than the current potential comparing port 411; first protection diode 50 can by electric current by, electric current excessive like this can not flow into Master control chip, thus when can avoid fault, Master control chip is burnt.
In order to avoid causing damage to the load of LED constant-current control circuit and the load outputs mouth that is connected on LED constant-current control circuit when power input port 10 both positive and negative polarity connects anti-situation; preferably, described LED constant-current control circuit can also comprise input reverse-connection protection module 60.This input reverse-connection protection module 60 is connected to power input port 10 place, described LED constant-current control circuit to be disconnected when electric current is reverse, thus Master control chip 41 grade can be avoided to be burnt because of power input port 10 both positive and negative polarity reversal connection.
As a kind of preferred implementation of the present invention; as shown in Figure 1; input reverse-connection protection module 60 comprises second switch element 61 and the first voltage-stabiliser tube 62; between the positive pole that second switch element 61 is connected on power input port 10 and negative pole; when positive pole and the negative pole reversal connection of power input port 10, second switch element 61 disconnects.
When the both positive and negative polarity reversal connection of power input port 10, second switch element 61 disconnects, and the voltage of subsequent conditioning circuit is held by the first voltage-stabiliser tube 62, thus the components and parts in electric current can be avoided to receive damage, and the unexpected power-off of load being connected on load outputs mouth 20 can be avoided.
In the present invention, the concrete form of second switch element 61 is not limited, as long as can disconnect when the both positive and negative polarity reversal connection of power input port 10.Such as, second switch element 61 can be diode, triode or metal-oxide-semiconductor.As a kind of preferred implementation of the present invention, as shown in Figure 1, second switch element 61 can be metal-oxide-semiconductor, the drain electrode of second switch element 61 is connected with the negative electricity of power input port, the grid of second switch element 61 is electrically connected with the positive pole of power input port 10, and the source electrode of second switch element 61 is electrically connected with the positive pole of the first voltage-stabiliser tube 62.
When the both positive and negative polarity of power input port 10 does not have reversal connection, second switch element 61 conducting, when the both positive and negative polarity reversal connection of power input port 10, second switch element 61 disconnects.
Usually, as shown in Figure 1, Master control chip 41 is provided with controls this Master control chip 41 and be energized or the switch pin 412 of power-off, when switch pin 412 is in high level, Master control chip 41 is energized, when the switch pin 412 of Master control chip 41 is in low level, and Master control chip 41 power-off.
In order to the load preventing Master control chip 41 and be connected on load outputs mouth 20 place receives damage because input voltage is too low; preferably; as shown in Figure 3; described LED constant-current control circuit can also comprise input undervoltage protection module 70; input undervoltage protection module 70 is connected between power input port 10 and switch pin 412, with the input voltage in power input port 10 lower than the first reference voltage V
1time to switch pin 412 output low level.Usually, the first reference voltage V
1can be 2.5V.Described first reference voltage can be determined according to different chip types.
As a kind of embodiment of the present invention; preferably; as shown in Figure 3; input undervoltage protection module 70 can comprise the second operational amplifier 71 and the 3rd switch element 72; second operational amplifier 71 can compare the input voltage of power input port 10 and described first reference voltage, when the input voltage of power input port 10 is lower than described first reference voltage V
1time, the second operational amplifier 71 exports high level to the 3rd switch element 72, and Master control chip 41, to switch pin 412 output low level, is closed by the 3rd switch element 72.
Similarly, the present invention is to the concrete form of the 3rd switch element 72 and be not construed as limiting, as long as can when the second operational amplifier 71 exports high level to the 3rd switch element 72 to switch pin 412 output low level.As one embodiment of the present invention, as shown in Figure 3, the 3rd switch element 72 can be metal-oxide-semiconductor, and the grid of the 3rd switch element 72 is electrically connected with the output of the second operational amplifier 71, the drain electrode of the 3rd switch element 72 is electrically connected with switch pin 412, the source ground of the 3rd switch element 72.As shown in Figure 3, if the second operational amplifier 71 exports high level, the 3rd switch element 72 conducting, due to the grounded drain of the 3rd switch element 72, therefore, to switch pin 412 output low level, thus can close Master control chip 41.
In the present invention, directly described first reference voltage V can be applied at the positive input of the second operational amplifier 71
1.Or can be the first reference voltage V by the voltage transitions of power input port 10
1, and then input to the positive input of the second operational amplifier 71.As shown in Figure 3, in order to be the first reference voltage V by the voltage transitions of power input port 10
1input undervoltage protection module 70 can also comprise the 3rd operational amplifier 73; the positive input of the 3rd operational amplifier 73 is electrically connected with power input port 10; the output of the 3rd operational amplifier 73 is electrically connected with the positive input of the second operational amplifier 71, being the first reference voltage V by the voltage transitions of power input port 10
1be applied to the second operational amplifier 71.
In order to protect the second operational amplifier 71, preferably, between the output and ground of the second operational amplifier 71, parallel connection second diode 74 can be protected.
In order to prevent inputting excessive voltage from power input port 10, damage is caused to other elements Master control chip 41 and circuit; preferably; as shown in Figure 4; described LED constant-current control circuit can also comprise input overvoltage protective module 80; input overvoltage protective module 80 is connected between power input port 10 and switch pin 412, with the voltage inputted in power input port 10 higher than the second reference voltage V
2time to switch pin 412 output low level, Master control chip 41 is closed.Usually, the second reference voltage V
2can be 2.5V, the second reference voltage V can be determined according to different Master control chips
2occurrence.
As a kind of embodiment of the present invention, as shown in Figure 4, input overvoltage protective module 80 and can comprise four-operational amplifier 81 and the 4th switch element 82, the four-operational amplifier 81 can to the input voltage of power input port 10 and the second reference voltage V
2compare, when the input voltage of power input port 10 is higher than described second reference voltage V
2time, Master control chip 41, to the 4th switch element 82 output low level, and by the 4th switch element 82 conducting, thus to switch pin 412 output low level, is closed by four-operational amplifier 81.
Similarly, the concrete form of the present invention to the 4th switch element 82 is not construed as limiting, if can four-operational amplifier 81 to during the 4th switch element 82 output low level to switch pin 412 output low level.As one embodiment of the present invention, as shown in Figure 4, the 4th switch element 82 can be diode, and the negative pole of the 4th switch element 82 is electrically connected with the output of four-operational amplifier 81, and the positive pole of the 4th switch element 82 is electrically connected with switch pin 412.When four-operational amplifier 81 output low level, the 4th switch element 82 conducting, due to the clamping action of diode, switch pin 412 is low level, thus is closed by Master control chip 41.
Similar with input undervoltage protection module 70, in the present invention, the second reference voltage V can be applied directly to the positive input of four-operational amplifier 81
2, can be also the second reference voltage V by the voltage transitions of power input port 10
2, be then applied to the positive input of four-operational amplifier 81.
Particularly; as shown in Figure 4; input overvoltage protective module 80 can also comprise the 5th operational amplifier 83; the positive input of the 5th operational amplifier 83 is electrically connected with power input port 10; the output of the 5th operational amplifier 83 is electrically connected with the positive input of four-operational amplifier 81, being the second reference voltage V by the voltage transitions of power input port 10
2be applied to described four-operational amplifier 81.
The load being docked at this load outputs mouth 20 in order to the voltage preventing load outputs mouth 20 from exporting is excessive is made city and is damaged; preferably; as shown in Figure 5; described LED constant-current control circuit can also comprise output over-voltage protection module 90; output over-voltage protection module 90 is connected between load outputs mouth 20 and switch pin 412, with the voltage at load outputs mouth 20 higher than the 3rd reference voltage V
3time to described switch pin 412 output low level, thus Master control chip 41 is closed.Usually, the 3rd reference voltage V
3can be 2.5V, the 3rd reference voltage V can be determined according to different Master control chips
3occurrence.
As a kind of embodiment of the present invention, as shown in Figure 5, the positive input that output over-voltage protection module 90 can comprise the 6th operational amplifier 91 and the 5th switch element the 92, six operational amplifier 91 is applied with the 3rd reference voltage V
3, the 6th operational amplifier 91 can to the output voltage of load outputs mouth 20 and the 3rd reference voltage V
3compare, when the output voltage of load outputs mouth 20 is higher than the 3rd reference voltage V
3time, Master control chip 41, to the 5th switch element 92 output low level, and by the 5th switch element 92 conducting, thus to switch pin 412 output low level, thus is closed by the 6th operational amplifier 91.In the present invention, the concrete form of the 5th switch element 92 is not also limited.
In execution mode in Figure 5,5th switch element 92 is diode, the positive pole of the 5th switch element 92 is electrically connected with switch pin 412, the negative pole of the 5th switch element 92 is connected with the output of the 6th operational amplifier 91, and the positive pole of the 5th switch element 92 is electrically connected with power input port 10.If output voltage is higher than the 3rd reference voltage V
3, so the 6th operational amplifier 91 is to the 5th switch element 92 output low level, and because the positive pole of the 5th switch element 92 is electrically connected with power input port 10, therefore, the 5th switch element 92 can be switched on.Because the 5th switch element 92 has clamping action, therefore Master control chip 41 to switch pin 412 output low level, and then can be closed by output over-voltage protection module 90.
One skilled in the art will appreciate that the positive pole of the 5th switch element 92 herein was both electrically connected with switch pin 412, be electrically connected with power input port 10 again.
As one embodiment of the present invention, the 3rd reference voltage V
3with the first reference voltage V
1equal.Therefore, in order to make the structure of LED constant-current control circuit of the present invention more simple, the positive input of the output of the 3rd operational amplifier 73 with the 6th operational amplifier 91 can be connected, thus the first reference voltage V that the 3rd operational amplifier 73 is exported
1as the 3rd reference voltage V
3be applied to the positive input of the 6th operational amplifier.
Output over-voltage protection module 90 can when when the overtension that load outputs mouth 20 exports, and available protecting load, avoids load to damage.
Below the preferred embodiment of the present invention is described in detail by reference to the accompanying drawings; but; the present invention is not limited to the detail in above-mentioned execution mode; within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.
It should be noted that in addition, each the concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode.In order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible compound mode.
In addition, also can carry out combination in any between various different execution mode of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.
Claims (16)
1. a LED constant-current control circuit, this LED constant-current control circuit comprises power input port, load outputs mouth, detection port and constant-current control module, described detection port is between described power input port and described load outputs mouth, described constant-current control module comprises Master control chip and detection signal amplification module, described Master control chip is connected electrically between described power input port and described load outputs mouth, described detection signal amplification module is connected electrically between the comparison port of described detection port and described Master control chip, so that the electrical signal transfer at described detection port place is compared port to described, it is characterized in that, the signal of telecommunication collected can be amplified different multiples by described detection signal amplification module, the signal of telecommunication of the different amplification exported according to described detection signal amplification module to enable described Master control chip and export the electric current of different size respectively,
Described detection signal amplification module comprises the first operational amplifier, the first resistance, the second resistance, the first switch element, described first resistance and described first switch elements in series are at the reverse input end of described first operational amplifier, described second resistance is in parallel with described first resistance and described first switch element, the positive input of described first operational amplifier is electrically connected with described detection port, one end ground connection of described first switch element;
Described detection signal amplification module also comprises control power supply, and this control power supply is electrically connected with described first switch element, to control switching on and off of described first switch element;
Described first switch element is triode, and the base stage of described first switch element is connected with described control power electric, and collector electrode and described first resistance of described first switch element electrically connect, the grounded emitter of described first switch element;
When controlling power supply and providing high level to the base stage of the first switch element, the first switching elements conductive, thus make by the electric current of the reverse input end of the first operational amplifier through the first resistance and the second resistance; When controlling power supply and not providing high level to the base stage of the first switch element, the first switch element not conducting, thus make to flow only through the second resistance by the electric current of the reverse input end of the first operational amplifier.
2. LED constant-current control circuit according to claim 1; it is characterized in that; described LED constant-current control circuit also comprises the first protection diode; the positive pole of this first protection diode is electrically connected with the described port that compares, and the negative pole of described first protection diode is electrically connected with the output of described detection signal amplification module.
3. LED constant-current control circuit as claimed in any of claims 1 to 2; it is characterized in that; described LED constant-current control circuit also comprises input reverse-connection protection module; this input reverse-connection protection module is connected to described power input port place, described LED constant-current control circuit to be disconnected when electric current is reverse.
4. LED constant-current control circuit according to claim 3, it is characterized in that, described input reverse-connection protection module comprises second switch element and the first voltage-stabiliser tube, between the positive pole that described second switch element is connected on described power input port and negative pole, second switch element is metal-oxide-semiconductor, the drain electrode of second switch element is connected with the negative electricity of power input port, the grid of second switch element is electrically connected with the positive pole of power input port, the source electrode of second switch element is electrically connected with the positive pole of the first voltage-stabiliser tube, when positive pole and the negative pole reversal connection of described power input port, described second switch element disconnects, voltage is held by the first voltage-stabiliser tube.
5. LED constant-current control circuit as claimed in any of claims 1 to 2, it is characterized in that, described Master control chip is provided with the switch pin controlling the energising of described Master control chip or power-off, when described switch pin is in high level, described Master control chip energising, when the switch pin of described Master control chip is in low level, described Master control chip power-off.
6. LED constant-current control circuit according to claim 5; it is characterized in that; described LED constant-current control circuit also comprises input undervoltage protection module; described input undervoltage protection module is connected between described power input port and described switch pin, with described power input port input voltage lower than during the first reference voltage to described switch pin output low level.
7. LED constant-current control circuit according to claim 6; it is characterized in that; described input undervoltage protection module comprises the second operational amplifier and the 3rd switch element; described second operational amplifier can compare the input voltage of described power input port and described first reference voltage; when the input voltage of described power input port is lower than described first reference voltage; described second operational amplifier exports high level to described 3rd switch element, and described 3rd switch element is to described switch pin output low level.
8. LED constant-current control circuit according to claim 7, it is characterized in that, described 3rd switch element is metal-oxide-semiconductor, the grid of described 3rd switch element is electrically connected with the output of described second operational amplifier, the drain electrode of described 3rd switch element is electrically connected with described switch pin, the source ground of described 3rd switch element.
9. LED constant-current control circuit according to claim 7; it is characterized in that; described input undervoltage protection module also comprises the 3rd operational amplifier; the positive input of the 3rd operational amplifier is electrically connected with described power input port; the output of described 3rd operational amplifier is electrically connected with the positive input of described second operational amplifier, being that described first reference voltage is applied to described second operational amplifier by the voltage transitions of described power input port.
10. LED constant-current control circuit according to claim 5; it is characterized in that; described LED constant-current control circuit also comprises input overvoltage protective module; described input overvoltage protective module is connected between described power input port and described switch pin, with described power input port input voltage higher than during the second reference voltage to described switch pin output low level.
11. LED constant-current control circuit according to claim 10; it is characterized in that; described input overvoltage protective module comprises four-operational amplifier and the 4th switch element; described four-operational amplifier can compare the input voltage of described power input port and described second reference voltage; when the input voltage of described power input port is higher than described second reference voltage; described four-operational amplifier is to described 4th switch element output low level; and by described 4th switching elements conductive, thus to described switch pin output low level.
12. LED constant-current control circuit according to claim 11, it is characterized in that, described 4th switch element is diode, and the negative pole of described 4th switch element is electrically connected with the output of described four-operational amplifier, and the positive pole of described 4th switch element is electrically connected with described switch pin.
13. LED constant-current control circuit according to claim 12; it is characterized in that; described input overvoltage protective module also comprises the 5th operational amplifier; the positive input of the 5th operational amplifier is electrically connected with described power input port; the output of described 5th operational amplifier is electrically connected with the positive input of described four-operational amplifier, being that described second reference voltage is applied to described four-operational amplifier by the voltage transitions of described power input port.
14. LED constant-current control circuit according to claim 5; it is characterized in that; described LED constant-current control circuit also comprises output over-voltage protection module; described output over-voltage protection model calling between described load outputs mouth and described switch pin, with described load outputs mouth voltage higher than during the 3rd reference voltage to described switch pin output low level.
15. LED constant-current control circuit according to claim 14, it is characterized in that, described output over-voltage protection module comprises the 6th operational amplifier and the 5th switch element, the positive input of described 6th operational amplifier is applied with the 3rd reference voltage, described 6th operational amplifier can compare the output voltage of described load outputs mouth and described 3rd reference voltage, when the output voltage of described load outputs mouth is higher than described 3rd reference voltage, described 6th operational amplifier is to described 5th switch element output low level, and by described 5th switching elements conductive, thus to described switch pin output low level.
16. LED constant-current control circuit according to claim 15, it is characterized in that, described 5th switch element is diode, the positive pole of described 5th switch element is electrically connected with described switch pin, the negative pole of described 5th switch element is connected with the output of described 6th operational amplifier, and the positive pole of described 5th switch element is electrically connected with described power input port.
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| CN109062304B (en) * | 2018-05-31 | 2024-04-26 | 北京励芯泰思特测试技术有限公司 | Constant current load circuit, electronic load and related system |
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| CN201608937U (en) * | 2009-07-01 | 2010-10-13 | 西安孚莱德光电科技有限公司 | Simple Smart Dimmable LED Driver |
| CN102833902A (en) * | 2011-06-14 | 2012-12-19 | 海洋王照明科技股份有限公司 | Boosting LED (light-emitting diode) constant-current drive circuit |
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| CN201608937U (en) * | 2009-07-01 | 2010-10-13 | 西安孚莱德光电科技有限公司 | Simple Smart Dimmable LED Driver |
| CN102833902A (en) * | 2011-06-14 | 2012-12-19 | 海洋王照明科技股份有限公司 | Boosting LED (light-emitting diode) constant-current drive circuit |
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