LED lamp bar short-circuit protection control device
Technical field
The utility model relates to the backlight control technology, particularly relates to a kind of control circuit with single channel or multi-way LED lamp bar short-circuit protection function for backlight control.
Background technology
The use of LCDs is very extensive at present, for example at television set, panel computer, notebook computer, the display of desktop computer, all used the liquid crystal display module in the electronic products such as mobile phone, in all demonstration modules, all used a material that is backlight, in backlight, generally all can place uniformly the light-emitting diode of some high brightness, allow these show that module can work, just need to allow these light-emitting diodes be that LED lamp bar can send the light of same brightness simultaneously, leaded light effect through backlight, it is soft just can to allow whole liquid crystal module send, light is realized display effect uniformly.In the prior art, usually all be provided with the LED short-circuit protection circuit, to realize the protection to LED lamp bar, still, these LED short-circuit protection circuits of prior art exist the circuit structure complexity, respond untimely, the drawback that production cost is higher.
The utility model content
The purpose of this utility model is to overcome the deficiency of prior art; a kind of LED lamp bar short-circuit protection control device is provided, can detects and protect control to the short circuit behavior of the LED lamp bar of single channel or multichannel, and it is simple to have a circuit structure; response is timely, the characteristics that production cost is low.
The technical scheme that its technical problem that solves the utility model adopts is: a kind of LED lamp bar short-circuit protection control device comprises:
One LED decides the current sample control circuit, is connected in the LED lamp bar current supply circuit, realizes deciding Current Control;
One switching circuit is connected in the LED lamp bar current supply circuit, and is to establish between LED lamp bar and the power supply, and the control end of switching circuit connects backlight control signal;
One LED short-circuit protection circuit; this LED short-circuit protection circuit is connected between the control end that LED decides current sample control circuit and switching circuit; this LED short-circuit protection circuit includes comparator; the in-phase input end of comparator is connected to LED and decides the current sample control circuit; the inverting input of comparator connects the threshold signal that presets; when the numerical value of the signal of the in-phase input end of described comparator during greater than the numerical value of the threshold signal of the inverting input of described comparator; this LED short-circuit protection circuit cuts off power supply by switching circuit and powers to LED lamp bar to the control end output control signal of switching circuit.
It is a plurality of that described LED decides the current sample control circuit, and each LED decides the current sample control circuit and is connected with a corresponding LED lamp bar respectively, and the in-phase input end of described comparator is decided the current sample control circuit with each LED respectively and is connected.
Described LED decides the current sample control circuit by the first triode, the second triode, the first resistance, the second resistance and the 3rd resistance consist of, the emitter of the first triode is connected to an end of the first resistance, the other end ground connection of the first resistance, the collector electrode of the first triode is connected to the negative pole end of LED lamp bar, the positive terminal of LED lamp bar is connected to switching circuit, one of the second resistance is connected to the positive terminal of LED lamp bar, the other end of the second resistance is connected to the collector electrode of the second triode, the grounded emitter of the second triode, the base stage of the second triode is connected to the emitter of the first triode, one of the 3rd resistance is connected to the collector electrode of the second triode, and the other end of the 3rd resistance is connected to the base stage of the first triode.
Described LED short-circuit protection circuit also comprises the 3rd triode; the 4th resistance; the 5th resistance; the 6th resistance; the 7th resistance; the first diode and the first electric capacity; the positive terminal of the first diode is connected to the collector electrode of described the first triode; the negative pole end of the first diode is connected to the in-phase input end of described comparator; the collector electrode of the 3rd triode is connected to the control end of described switching circuit; the grounded emitter of the 3rd triode; one of the 4th resistance is connected to the base stage of the 3rd triode; the other end ground connection of the 4th resistance; one of the 5th resistance is connected to the base stage of the 3rd triode; the output of another termination comparator of the 5th resistance; the output of one termination comparator of the 6th resistance; another termination comparator of the 6th resistance connect power end; the in-phase input end of one termination comparator of the 7th resistance; the earth terminal of another termination comparator of the 7th resistance; the in-phase input end of one termination comparator of the first electric capacity, the earth terminal of another termination comparator of the first electric capacity.
Described switching circuit comprises metal-oxide-semiconductor, the 4th triode, the 8th resistance, the 9th resistance, the tenth resistance and the 11 resistance, the source electrode of metal-oxide-semiconductor is connected to described power supply, the drain electrode of metal-oxide-semiconductor is connected to the positive terminal of described LED lamp bar, one end of the 8th resistance connects respectively the collector electrode of backlight control signal and the 3rd triode, the other end of the 8th resistance is connected to the base stage of the 4th triode, the base stage of one termination the 4th triode of the 9th resistance, the other end ground connection of the 9th resistance, the grounded emitter of the 4th triode, the collector electrode of the 4th triode is connected to an end of the tenth resistance, the other end of the tenth resistance is connected to the grid of metal-oxide-semiconductor, the source electrode of one termination metal-oxide-semiconductor of the 11 resistance, the grid of another termination metal-oxide-semiconductor of the 11 resistance.
A kind of LED lamp bar short-circuit protection control device of the present utility model is that the electric current that flows through LED lamp bar is controlled, and current signal is converted to voltage signal, realizes deciding electric current, ensures the useful life of LED.By detecting the voltage of the first triode current collection level; deliver to the in-phase input end of comparator; the threshold signal that namely presets with the reference settings voltage of inverting input compares; when the LED lamp is short-circuited fault; the voltage of the first triode current collection level rises, comparator output signal upset, control backlight switch signal; cut off the LED power supply, reach the function of LED protection.For the LED lamp of multichannel, by a plurality of the first diodes, allow a plurality of the first triode current collection step voltages consist of and logical relation, reach the multi-way LED lamp defencive function.
A kind of LED lamp bar short-circuit protection control device of the present utility model, wherein, LED decides the current sample control circuit flows through resistance by detection voltage, the current signal signal conversion voltage, the control triode is operated in the amplification region, realize deciding Current Control, peripheral components is simple, only needs two triodes and three resistance; The LED short-circuit protection circuit is by detecting the voltage of current collection level on the first triode, deliver to the in-phase input end of comparator, with the reference settings voltage ratio of inverting input, when the LED lamp is short-circuited fault, the voltage of triode current collection level rises, comparator output signal upset, control backlight switch signal, cut off the LED power supply, reach the function of LED protection; When having the multi-way LED lamp bar to need short-circuit protection; adopt discrete the first diode; the LED of multichannel is decided current collection step voltage on the first triode of current sample control circuit consists of and logical relation; reach protection LED multi-path function; any paths of LEDs lamp bar breaks down; can control backlight control signal, when backlight control signal is low level, cut off the LED power supply.
A kind of LED lamp bar short-circuit protection control device of the present utility model, to the LED current sample, current signal converts voltage signal to, and the resistance of the Vbe voltage of the electric current that the first resistance of current detecting flows through=second triode/detection resistance (i.e. the first resistance) realizes deciding electric current; The first transistor collector voltage is detected, compare with the reference voltage of setting, because the first triode is operated in the amplification region, flow through the electric current I _ LED of the first triode current collection level in situation about remaining unchanged, the voltage of the first transistor collector can be followed the state variation of LED lamp bar, the conducting voltage of a general LED lamp is 3.3V (Typ), so every short circuit one LEDs of LED lamp bar, the first transistor collector 3.3V (Typ) that can rise.Therefore can set neatly the reference voltage of comparator, set several lamp protective circuits of short circuit and begin to start to control.
The beneficial effects of the utility model are; owing to adopted LED to decide the current sample control circuit; switching circuit and LED short-circuit protection circuit consist of LED lamp bar short-circuit protection control device; and LED decides the current sample control circuit and is connected in the LED lamp bar current supply circuit; realize deciding Current Control; switching circuit is connected in the LED lamp bar current supply circuit; and switching circuit is to establish between LED lamp bar and the power supply; the control end of switching circuit connects backlight control signal; the LED short-circuit protection circuit then is connected between the control end that LED decides current sample control circuit and switching circuit; this LED short-circuit protection circuit includes comparator; the in-phase input end of comparator is connected to LED and decides the current sample control circuit; the inverting input of comparator connects the threshold signal that presets; when the numerical value of the signal of the in-phase input end of described comparator during greater than the numerical value of the threshold signal of the inverting input of described comparator; this LED short-circuit protection circuit cuts off power supply by switching circuit and powers to LED lamp bar to the control end output control signal of switching circuit.After adopting this structure, it is simple to the utlity model has the circuit structure, response in time, characteristics that production cost is low, and can adjust fixed current controling circuit according to different lamp bar parameters are set a protection point reference voltage flexibly, guarantee product normal reliable steady operation.
Below in conjunction with drawings and Examples the utility model is described in further detail; But a kind of LED lamp bar short-circuit protection control device of the present utility model is not limited to embodiment.
Description of drawings
Fig. 1 is embodiment one theory diagram of the present utility model;
Fig. 2 is embodiment one circuit theory diagrams of the present utility model;
Fig. 3 is embodiment two theory diagrams of the present utility model;
Fig. 4 is embodiment two circuit theory diagrams of the present utility model.
Embodiment
Embodiment one,
Referring to Fig. 1, shown in Figure 2, a kind of LED lamp bar short-circuit protection control device of the present utility model comprises:
One LED decides current sample control circuit 1, is connected in the LED lamp bar current supply circuit, realizes deciding Current Control;
One switching circuit 2 is connected in the LED lamp bar current supply circuit, and is to establish between LED lamp bar 10 and the power supply V_LED, and the control end of switching circuit 2 connects backlight control signal BACKLIGHT_ON;
One LED short-circuit protection circuit 3; this LED short-circuit protection circuit 3 is connected between the control end that LED decides current sample control circuit 1 and switching circuit 2; this LED short-circuit protection circuit 3 includes comparator; the in-phase input end of comparator is connected to LED and decides current sample control circuit 1; the inverting input of comparator connects the threshold signal that presets; when the numerical value of the signal of the in-phase input end of described comparator during greater than the numerical value of the threshold signal of the inverting input of described comparator; this LED short-circuit protection circuit 3 cuts off power supply to 10 power supplies of LED lamp bar to the control end output control signal of switching circuit 2 by switching circuit 2.
Described LED decides current sample control circuit 1 by the first triode V5, the second triode V4, the first resistance R 11, the second resistance R 9 and the 3rd resistance R 10 consist of, the emitter of the first triode V5 is connected to an end of the first resistance R 11, the other end ground connection of the first resistance R 11, the collector electrode of the first triode V5 is connected to the negative pole end of LED lamp bar, the positive terminal of LED lamp bar is connected to switching circuit, one of the second resistance R 9 is connected to the positive terminal of LED lamp bar, the other end of the second resistance R 9 is connected to the collector electrode of the second triode V4, the grounded emitter of the second triode V4, the base stage of the second triode V4 is connected to the emitter of the first triode V5, one of the 3rd resistance R 10 is connected to the collector electrode of the second triode V4, and the other end of the 3rd resistance R 10 is connected to the base stage of the first triode V5.
Described LED short-circuit protection circuit 2 also comprises the 3rd triode V3; the 4th resistance R 5; the 5th resistance R 6; the 6th resistance R 7; the 7th resistance R 8; the first diode D1 and the first capacitor C 1; the positive terminal of the first diode D1 is connected to the collector electrode of described the first triode V5; the negative pole end of the first diode D1 is connected to the in-phase input end of described comparator; the collector electrode of the 3rd triode V3 is connected to the control end of described switching circuit; the grounded emitter of the 3rd triode V3; one of the 4th resistance R 5 is connected to the base stage of the 3rd triode V3; the other end ground connection of the 4th resistance R 5; one of the 5th resistance R 6 is connected to the base stage of the 3rd triode V3; the output of another termination comparator of the 5th resistance R 6; the output of one termination comparator of the 6th resistance R 7; another termination comparator of the 6th resistance R 7 connect power end; the in-phase input end of one termination comparator of the 7th resistance R 8; the earth terminal of another termination comparator of the 7th resistance R 8; the in-phase input end of one termination comparator of the first capacitor C 1, the earth terminal of another termination comparator of the first capacitor C 1.
Described switching circuit 3 comprises metal-oxide-semiconductor V1, the 4th triode V2, the 8th resistance R 4, the 9th resistance R 3, the tenth resistance R 2 and the 11 resistance R 1, the source electrode of metal-oxide-semiconductor V1 is connected to described power supply V_LED, the drain electrode of metal-oxide-semiconductor V1 is connected to the positive terminal of described LED lamp bar, one end of the 8th resistance R 4 connects respectively the collector electrode of backlight control signal BACKLIGHT_ON and the 3rd triode V3, the other end of the 8th resistance R 4 is connected to the base stage of the 4th triode V2, the base stage of one termination the 4th triode V2 of the 9th resistance R 3, the other end ground connection of the 9th resistance R 3, the grounded emitter of the 4th triode V2, the collector electrode of the 4th triode V2 is connected to an end of the tenth resistance R 2, the other end of the tenth resistance R 2 is connected to the grid of metal-oxide-semiconductor V1, the source electrode of one termination metal-oxide-semiconductor V1 of the 11 resistance R 1, the grid of another termination metal-oxide-semiconductor V1 of the 11 resistance R 1.
When control signal BACKLIGHT_ON is high level, metal-oxide-semiconductor V1 conducting, LED power supply V_LED begins to make LED lamp bar current flowing, the I_LED electric current increases gradually, the resistance value of the Vbe magnitude of voltage of I_LED set point=second triode V4/first resistance R 11, the Vbe magnitude of voltage of general the second triode V4 is 0.6V, when I_LED reaches set point, if I_LED continues to increase, the Ib electric current of the second triode V4 increases, and therefore the IC electric current of the second triode V4 increases, and the first triode V5 is operated in the amplification region, the Ib electric current of the first triode V5 reduces, the IC electric current of the first triode V5 reduces, and I_LED is reduced, whole circuit closed loop, play degenerative effect, realize deciding Current Control.
In the situation of normal operation, the conduction voltage drop of the first triode V5 current collection step voltage Vc=V_LED-lamp bar, generally speaking, in order to guarantee the conducting of LED lamp bar, V_LED voltage design load can be than the conduction voltage drop of lamp bar about high 1V, and therefore the first triode V5 current collection step voltage Vc is about 1V.
The conducting voltage of a general LED lamp is 3.3V (Typ), and simultaneously the first triode V5 is operated in the amplification region, so every short circuit one LEDs of LED lamp bar, the first triode V5 current collection step voltage Vc 3.3V (Typ) that can rise.The first triode V5 current collection step voltage Vc delivers to the in-phase input end of comparator; the protective valve threshold voltage of setting with the inverting input of comparator compares; if Vc voltage is higher than the voltage with reference to V_Reference; comparator output high level; the BACKLIGHT_ON control signal is pulled down to low level; metal-oxide-semiconductor V1 cut-off, the protection of LED lamp bar.
Embodiment two,
Referring to Fig. 3, shown in Figure 4, a kind of LED lamp bar short-circuit protection control device of the present utility model, be that with the difference of embodiment one described LED decides current sample control circuit 2 for a plurality of, each LED decides current sample control circuit 2 and is connected with a corresponding LED lamp bar respectively; The in-phase input end of described comparator is decided current sample control circuit 1 with each LED respectively and is connected, by a plurality of the first diodes, the first triode current collection step voltage that allows a plurality of LED decide current sample control circuit 1 consist of and logical relation.
Such as; another LED decides current sample control circuit 1 by the first triode V7; the second triode V6; the first resistance R 14; the second resistance R 12 and the 3rd resistance R 13 consist of; then the first diode of LED short-circuit protection circuit 2 also is a plurality of; wherein; the first diode D1 is used for connecting by the first triode V5; the second triode V4; the first resistance R 11; the LED that the second resistance R 9 and the 3rd resistance R 10 consist of decides current sample control circuit 1; the first diode D2 is used for connecting by the first triode V7; the second triode V6; the first resistance R 14; the LED that the second resistance R 12 and the 3rd resistance R 13 consist of decides current sample control circuit 1, and the rest may be inferred.
A kind of LED lamp bar short-circuit protection control device of the present utility model is that the electric current that flows through LED lamp bar is controlled, and current signal is converted to voltage signal, realizes deciding electric current, ensures the useful life of LED.By detecting the voltage of the first triode current collection level; deliver to the in-phase input end of comparator; the threshold signal that namely presets with the reference settings voltage of inverting input compares; when the LED lamp is short-circuited fault; the voltage of the first triode current collection level rises, comparator output signal upset, control backlight switch signal; cut off the LED power supply, reach the function of LED protection.For the LED lamp of multichannel, by a plurality of the first diodes, allow a plurality of the first triode current collection step voltages consist of and logical relation, reach the multi-way LED lamp defencive function.
A kind of LED lamp bar short-circuit protection control device of the present utility model, wherein, LED decides the current sample control circuit flows through resistance by detection voltage, the current signal signal conversion voltage, the control triode is operated in the amplification region, realize deciding Current Control, peripheral components is simple, only needs two triodes and three resistance; The LED short-circuit protection circuit is by detecting the voltage of current collection level on the first triode, deliver to the in-phase input end of comparator, with the reference settings voltage ratio of inverting input, when the LED lamp is short-circuited fault, the voltage of triode current collection level rises, comparator output signal upset, control backlight switch signal, cut off the LED power supply, reach the function of LED protection; When having the multi-way LED lamp bar to need short-circuit protection; adopt discrete the first diode; the LED of multichannel is decided current collection step voltage on the first triode of current sample control circuit consists of and logical relation; reach protection LED multi-path function; any paths of LEDs lamp bar breaks down; can control backlight control signal, when backlight control signal is low level, cut off the LED power supply.
A kind of LED lamp bar short-circuit protection control device of the present utility model, to the LED current sample, current signal converts voltage signal to, and the resistance of the Vbe voltage of the electric current that the first resistance of current detecting flows through=second triode/detection resistance (i.e. the first resistance) realizes deciding electric current; The first transistor collector voltage is detected, compare with the reference voltage of setting, because the first triode is operated in the amplification region, flow through the electric current I _ LED of the first triode current collection level in situation about remaining unchanged, the voltage of the first transistor collector can be followed the state variation of LED lamp bar, the conducting voltage of a general LED lamp is 3.3V (Typ), so every short circuit one LEDs of LED lamp bar, the first transistor collector 3.3V (Typ) that can rise.Therefore can set neatly the reference voltage of comparator, set several lamp protective circuits of short circuit and begin to start to control.
Above-described embodiment only is used for further specifying a kind of LED lamp bar short-circuit protection control device of the present utility model; but the utility model is not limited to embodiment; every foundation technical spirit of the present utility model all falls in the protection range of technical solutions of the utility model any simple modification, equivalent variations and modification that above embodiment does.