CN203590545U - Constant current control circuit and system and liquid crystal display television - Google Patents
Constant current control circuit and system and liquid crystal display television Download PDFInfo
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- CN203590545U CN203590545U CN201320686280.7U CN201320686280U CN203590545U CN 203590545 U CN203590545 U CN 203590545U CN 201320686280 U CN201320686280 U CN 201320686280U CN 203590545 U CN203590545 U CN 203590545U
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- 238000006243 chemical reaction Methods 0.000 claims abstract description 45
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- 238000005070 sampling Methods 0.000 abstract description 9
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Abstract
The application discloses constant current control circuit and system and LCD TV, constant current control circuit includes: the power conversion circuit, the sampling circuit, the master control display chip and the driving circuit set various constant current rules in the master control display chip, and select the corresponding constant current rule in the master control display chip when the constant current parameters need to be adjusted. The main control display chip obtains a feedback signal obtained by sampling of the sampling circuit, the signal is compared with a current value preset in a selected constant current rule through a PID algorithm, a PWM duty ratio signal is output to the driver, the driver controls the output current of the power conversion circuit according to the PWM duty ratio signal, and therefore the purpose that a constant current power supply can be suitable for backlight plates of various specifications is achieved.
Description
Technical field
The application relates to constant current control technology field, more particularly, relates to a kind of constant-current controller backlight.
Background technology
LCD TV replaces traditional picture tube TV and plasm TV, the leading position of having captured market rapidly with its superior performance.
In prior art, the constant flow regulation system backlight of LCD TV mainly comprises constant-current supply and backlight screen, wherein constant-current supply comprises: DC power supply, power conversion circuit, sample circuit and constant current integrated circuit modules, wherein constant current integrated circuit modules is corresponding with the specification of back light system.When prior art is carried out constant flow regulation backlight, sample circuit gathers the output current signal of power conversion circuit by backlight screen, and output current signal is sent to constant current integrated circuit modules, constant current integrated circuit modules compares the current signal collecting and preset reference signal, thereby produce pwm signal (Pulse Width Modulation, pulse width modulating signal) output current is controlled, the constant current parameter of constant-current supply is generally determined by the size of constant current resistance, so the value of the output current of every kind of constant-current supply is changeless, the backlight of different size need to drive with the constant-current supply of different size.
Visible, in prior art, the backlight of every kind of specification all needs to drive with the constant-current supply of corresponding specification, thereby the specification of the constant-current supply causing is varied, is difficult to carry out unified management.
Utility model content
In view of this, the application provides a kind of constant-current control circuit, to reach the object that reduces constant-current supply specification.
To achieve these goals, the existing scheme proposing is as follows:
A kind of constant-current control circuit, comprising:
The power conversion circuit that input is connected with DC power supply, the power take-off of described power conversion circuit is connected with the input of backlight;
The sample circuit that input is connected with the output of backlight, described sample circuit is used for gathering output current or the voltage signal of power conversion circuit, and this signal is sent to master control display chip;
The master control display chip that first input end is connected with described sample circuit output, be used for the output current signal of the power conversion circuit that described sample circuit is detected by described backlight, compare with the predetermined current value in the default constant current rule of master control display chip, and output pulse width modulation signal PWM, in described master control display chip, prestore the default constant current rule of N kind, described N is not less than 1 positive integer;
The drive circuit that input is connected with the output of described master control display chip, the output of described drive circuit is connected with the power control end of described power conversion circuit.
Preferably, in above-mentioned constant-current control circuit, also comprise:
The protective circuit that first input end is connected with power conversion circuit power take-off; the second input of described protective circuit is connected with the current output terminal of power conversion circuit; the first output of described protective circuit is connected with the protection end of drive circuit, and the second output of described protective circuit is connected with the second input of described master control display chip.
Preferably, in above-mentioned constant-current control circuit, power conversion circuit comprises:
The inductance that first end is connected with DC power supply;
Anodal the first electric capacity being connected with the first end of inductance;
The anode diode that is connected with the second end of inductance;
Anodal the second electric capacity and the 3rd electric capacity being connected with the negative electrode of diode;
The minus earth of the first electric capacity, the second electric capacity and the 3rd electric capacity;
The field effect transistor that drain electrode is connected with the second end of inductance;
The positive pole of the first electric capacity is as the input of power conversion circuit;
The negative electrode of diode is as the power take-off of power conversion circuit;
The grid of field effect transistor is as the power control end of power conversion circuit;
The source electrode of field effect transistor is as the current output terminal of power conversion circuit.
Preferably, in above-mentioned constant-current control circuit, sample circuit comprises:
The 14 resistance of first end ground connection, the second end of the 14 resistance is connected with the output of backlight;
The 19 resistance being connected with the second end of the 14 resistance;
One end is connected other end ground connection the 7th electric capacity with the 19 resistance;
The common port of the 14 resistance and the 19 resistance is as the input of sample circuit;
The common port of the 19 resistance and the 7th electric capacity is as sample circuit output.
Preferably, in above-mentioned constant-current control circuit, master control display chip comprises:
TSUMV59 chip or MSD3393 chip;
The ADC port of TSUMV59 or MSD3393 chip is as the first input end of master control display chip;
The IO port of TSUMV59 or MSD3393 chip is as the second input of master control display chip;
The PWM port of TSUMV59 or MSD3393 chip is as the output of master control display chip.
Preferably, in above-mentioned constant-current control circuit, drive circuit comprises:
The 9th resistance that first end is connected with the output of master control display chip;
The 11 resistance being connected with the 9th resistance the second end;
The 5th triode that base stage is connected with the 9th resistance the second end;
The second resistance that first end is connected with the collector electrode of the 5th triode;
The 3rd triode that base stage is connected with the collector electrode of the 5th triode;
The 3rd resistance that first end is connected with the 3rd transistor emitter;
The 8th resistance that first end is connected with the collector electrode of the 3rd triode;
The first triode that base stage is connected with the second end of the 8th resistance and the 4th triode;
The 5th resistance that first end is connected with the emitter of the 4th triode with the first triode;
The 6th resistance that first end is connected with the second end of the 5th resistance;
The collector electrode of the 4th triode, the emitter of the 5th triode, the second end of the 11 resistance and the second end ground connection of the 6th resistance;
The second end, the second end of the 3rd resistance and the collector electrode of the first triode of the second resistance are connected with power supply VCC;
The first end of the 9th resistance is as the input of drive circuit;
The base stage of the 4th triode is as the protection end of drive circuit;
The second end of the 5th resistance is as the output of drive circuit.
Preferably, in above-mentioned constant-current control circuit, protective circuit comprises:
The first resistance, the 4th resistance, the 7th resistance, the 20 resistance and the 16 resistance of series connection successively;
The 12 resistance, the 15 resistance and the 17 resistance of series connection successively, one end ground connection that the 12 resistance is not connected with the 15 resistance;
The 13 resistance that first end is connected with the common port of the 20 resistance with the 7th resistance, the second end ground connection of the 13 resistance;
The switching diode that first input end is connected with one end that the 16 resistance is not connected with the 20 resistance;
The tenth resistance that first end is connected with the output of switching diode;
The 6th triode that base stage is connected with the tenth resistance the second end;
The 7th resistance that first end is connected with the tenth resistance the second end;
Four electric capacity in parallel with the 7th resistance;
One end is connected other end ground connection with the 17 resistance the 5th electric capacity with the common port of the 15 resistance;
The 18 resistance that first end is connected with the second input of switching diode;
One end is connected with the second end of the 18 resistance, the 8th electric capacity of other end ground connection;
One end that the second input of switching diode is not connected with the 5th electric capacity with the 17 resistance is connected;
One end is connected with the 20 resistance common port with the 16 resistance, the 6th electric capacity of other end ground connection;
The transport and placing device that the first pin is connected with the second input of switching diode;
The 3rd pin of transport and placing device is connected with the common port of the 17 resistance with the 5th electric capacity; The 4th pin ground connection of transport and placing device; The 5th pin of transport and placing device is connected with the common port of the 20 resistance with the 16 resistance; The 7th pin of transport and placing device is connected with the first input end of switching diode;
One end not being connected with the 4th resistance of the first resistance is as the first input end of protective circuit;
The common port of the 15 resistance and the 12 resistance is as the second input of protective circuit;
The collector electrode of the 6th triode is as the first output of protective circuit;
The second end of described the 18 resistance is as the second output of protective circuit.
Preferably, in above-mentioned constant-current control circuit, transport and placing device, comprising: LM2904 transport and placing device.
A kind of Constant Current Control System backlight, comprising: DC power supply, backlight and above-mentioned any one constant-current control circuit.
A kind of LCD TV, comprising: above-mentioned any one constant-current control circuit.
From above-mentioned technical scheme, can find out, the disclosed constant-current control circuit of the application, by multiple constant current rule is set in master control display chip, when needs are adjusted constant current parameter, by choosing corresponding constant current rule in master control display chip, obtain the sample circuit feedback signal obtaining of sampling, master control display chip is by PID(proportion integration differentiation control algolithm) algorithm compares current value default in this signal and the constant current rule chosen, redefine PWM duty ratio, by the output current of the PWM duty cycling power translation circuit that redefines, visible the application by arranging multiple constant current rules in master control display chip, when needs change constant current parameter, user can be directly by choosing corresponding default constant current rule in described master control display chip, thereby reach the object of the backlight that a kind of constant-current supply can suitable for various size.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiment of the application, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the disclosed a kind of constant-current control circuit structure chart of the embodiment of the present application;
Fig. 2 is the disclosed a kind of constant-current control circuit structure chart of another embodiment of the application;
Fig. 3 is the disclosed a kind of constant-current control circuit structure chart of another embodiment of the application;
Fig. 4 is the flow chart of the data operation process of the open master control display chip of the embodiment of the present application.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present application, the technical scheme in the embodiment of the present application is clearly and completely described, obviously, described embodiment is only the application's part embodiment, rather than whole embodiment.Based on the embodiment in the application, those of ordinary skills are not making the every other embodiment obtaining under creative work prerequisite, all belong to the scope of the application's protection.
The application discloses a kind of constant-current control circuit, to solve the numerous and jumbled problem of specification of constant-current supply of the prior art.
Referring to Fig. 1, the structure chart of a kind of constant-current control circuit that Fig. 1 provides for the embodiment of the present application.
The constant-current control circuit that the application provides, comprising: the power conversion circuit 2 that input is connected with DC power supply 1, and the power take-off of power conversion circuit 2 is connected with the input of backlight 3;
The sample circuit 4 that input is connected with the output of backlight 3;
The master control display chip 5 that first input end is connected with sample circuit 4 outputs, for the output current signal of power conversion circuit 2 and the predetermined current value of default constant current rule that sample circuit 4 is detected by backlight 3, compare, and output pulse width modulation signal, in master control display chip 5, prestore the default constant current rule of N kind, N is not less than 1 positive integer;
The drive circuit 6 that input is connected with the output of master control display chip 5, drive circuit 6 outputs are connected with the power control end of power conversion circuit 2.
In the constant-current control circuit that the application provides, in master control display chip, be provided with multiple default constant current rule, and every kind of corresponding predetermined current value of default constant current rule.Sample circuit gathers the output current signal of power conversion circuit by backlight, and this current signal is sent to master control display chip, when master control display chip gets after current signal, the predetermined current value that this current signal is corresponding with current constant current rule compares, determine corresponding PWM duty cycle signals, and this PWM duty cycle signals is sent to drive circuit, drive circuit is modulated according to the output current of PWM duty cycle signals power ratio control translation circuit, when need constant-current control circuit constant current parameter time, user can directly choose required default constant current rule by master control display chip, technical scheme in visible the application, can directly choose required default constant current rule by master control display chip, complete the modulation to controlling power conversion circuit output current, do not need by changing constant current resistance, so the constant-current source of the constant-current circuit that application the application provides can the different backlight of suitable for various size.
Referring to Fig. 2, the structure chart of the constant-current control circuit that Fig. 2 provides for another embodiment of the application.
Be understandable that, for better backlight is protected, the constant-current control circuit providing with respect to a upper embodiment, the constant-current control circuit that the present embodiment provides also comprises:
The protective circuit 7 that first input end is connected with power conversion circuit 2 power take-offs; the second input of protective circuit 7 is connected with the current output terminal of power driving circuit 6; the first output of protective circuit 7 is connected with the protection end of drive circuit 6, and the second output of protective circuit is connected with the second input of master control display chip 5.
Referring to Fig. 3, the structure chart of the constant-current control circuit that Fig. 3 provides for another embodiment of the application.
Referring to Fig. 3, be understandable that, the power conversion circuit in the above-mentioned all embodiment of the application, can comprise:
The inductance T that first end is connected with DC power supply;
Anodal the first capacitor C 1 being connected with the first end of inductance T;
The anode diode D1 that is connected with the second end of inductance T;
Anodal the second capacitor C 2 and the 3rd capacitor C 3 being connected with the negative electrode of diode D1;
The minus earth of the first capacitor C 1, the second capacitor C 2 and the 3rd capacitor C 3;
The field effect transistor Q2 that drain electrode is connected with the second end of inductance T;
The positive pole of the first capacitor C 1 is as the input of power conversion circuit;
The negative electrode of diode D1 is as the power take-off of power conversion circuit;
The grid of field effect transistor Q2 is as the power control end of power conversion circuit;
The source electrode of field effect transistor Q2 is as the current output terminal of power conversion circuit.
Referring to Fig. 3, be understandable that, in the above-mentioned all embodiment of the application, sample circuit can comprise:
The second end of the 14 resistance R 14, the 14 resistance R 14 of first end ground connection is connected with the output of backlight;
The 19 resistance R 19 being connected with the second end of the 14 resistance R 14;
One end is connected other end ground connection the 7th capacitor C 7 with the 19 resistance R 19;
The common port of the 14 resistance R 14 and the 19 resistance R 19 is as the input of sample circuit;
The common port of the 19 resistance R 19 and the 7th capacitor C 7 is as sample circuit output.
Be understandable that, in the above-mentioned all embodiment of the application, master control display chip can comprise:
TSUMV59 chip or MSD3393 chip;
Wherein, the ADC port of TSUMV59 or MSD3393 chip is used as the first input end of master control display chip;
The IO port of TSUMV59 or MSD3393 chip is brought in use as the second input of master control display chip;
The PWM port of TSUMV59 or MSD3393 chip is brought in use as the output of master control display chip.
When TSUMV59 or MSD3393 chip get by ADC port the sample rate current that sample circuit collects, by the pid algorithm of this built-in chip type, process sample rate current and the predetermined current value corresponding with the constant current rule of choosing in current TS UMV59 or MSD3393 chip, obtain error adjusted value, then by PWM value and the error adjusted value of current TS UMV59 or the output of MSD3393 chip, output PWM duty cycle signals is to driver, driver is by the conducting state of PWM duty cycle signals control field effect transistor, thus the modulation of realization to constant current output.
Certainly TSUMV59 chip can be specially TSUMV59XE-Z1 chip, and MSD3393 chip can be specially MSD3393LU chip.
Referring to Fig. 4, Fig. 4 is the flow chart of the data operation process of master control display chip in the embodiment of the present application:
This process comprises:
Step S401, calculates current error: e (k)=r (k)-u (k);
Step S402, proportional output: Up (k)=Kp*e (k);
Step S403, integration item output: Ui (k)=Ki*e (k)+u (k-1);
Step S404:PI adjusts parameter: P (k)=up (k)+u (k);
Step S405: upgrade output duty cycle;
Step S406:u (k-1)=u (k).
Wherein, u (k) is the current value of current sampling, r (k) is predetermined current value, u (k-1) is current sampling data last time, e (k) is this sample rate current error amount, P (k) is PWM duty ratio, and Kp is that ratio is adjusted coefficient, and Ki is that integration is adjusted coefficient.
Referring to Fig. 3, be understandable that, in the above-mentioned all embodiment of the application, drive circuit can comprise:
The 9th resistance R 9 that first end is connected with the output of master control display chip;
The 11 resistance R 11 being connected with the 9th resistance R 9 second ends;
The 5th triode Q5 that base stage is connected with the 9th resistance R 9 second ends;
The second resistance R 2 that first end is connected with the collector electrode of the 5th triode Q5;
The 3rd triode Q3 that base stage is connected with the collector electrode of the 5th triode Q5;
The 3rd resistance R 3 that first end is connected with the 3rd triode Q3 emitter;
The 8th resistance R 8 that first end is connected with the collector electrode of the 3rd triode Q3;
The first triode Q1 that base stage is connected with the second end of the 8th resistance R 5 and the 4th triode 14;
The 5th resistance R 5 that first end is connected with the emitter of the 4th triode Q4 with the first triode Q1;
The 6th resistance R 6 that first end is connected with the second end of the 5th resistance R 5;
The collector electrode of the 4th triode Q4, the emitter of the 5th triode Q5, the second end of the 11 resistance R 11 and the second end ground connection of the 6th resistance R 6;
The second end, the second end of the 3rd resistance R 3 and the collector electrode of the first triode Q1 of the second resistance R 2 are connected with power supply VCC;
The first end of the 9th resistance R 9 is as the input of drive circuit;
The base stage of the 4th triode Q4 is as the protection end of drive circuit;
The second end of the 5th resistance R 5 is as the output of drive circuit.
Referring to Fig. 3, in the above-mentioned all embodiment of the application, protective circuit can comprise:
The first resistance R 1, the 4th resistance R 4, the 7th resistance R the 7, the 20 resistance R the 20 and the 16 resistance R 16 of series connection successively;
One end ground connection that the 12 resistance R the 12, the 15 resistance R 15 of series connection and the 17 resistance R 17, the 12 resistance R 12 are not connected with the 15 resistance R 15 successively;
The second end ground connection of the 13 resistance R 13, the 13 resistance R 13 that first end is connected with the common port of the 20 resistance R 20 with the 7th resistance R 7;
The switching diode D2 that first input end is connected with one end that the 16 resistance R 16 is not connected with the 20 resistance R 20;
The tenth resistance R 10 that first end is connected with the output of switching diode D2;
The 6th triode Q6 that base stage is connected with the tenth resistance R 10 second ends;
The 7th resistance R 7 that first end is connected with the tenth resistance R 10 second ends;
Four capacitor C 4 in parallel with the 7th resistance R 7;
One end is connected other end ground connection with the 17 resistance R 17 the 5th capacitor C 5 with the common port of the 15 resistance R 15;
The 18 resistance R 18 that first end is connected with the second input of switching diode D2;
One end is connected with the second end of the 18 resistance R 18, the 8th capacitor C 8 of other end ground connection;
One end that the second input of switching diode D2 is not connected with the 5th capacitor C 5 with the 17 resistance R 17 is connected;
One end is connected with the 20 resistance R 20 common ports with the 16 resistance R 16, the 6th capacitor C 6 of other end ground connection;
The transport and placing device U1 that the first pin is connected with the second input of switching diode D2;
The 3rd pin of transport and placing device U1 is connected with the common port of the 17 resistance R 17 with the 5th capacitor C 5; The 4th pin ground connection of transport and placing device U1; The 5th pin of transport and placing device U1 is connected with the common port of the 20 resistance R 20 with the 16 resistance R 16; The 7th pin of transport and placing device U1 is connected with the first input end of switching diode D2;
One end not being connected with the 4th resistance R 4 of the first resistance R 1 is as the first input end of protective circuit;
The common port of the 15 resistance R 15 and the 12 resistance R 12 is as the second input of protective circuit;
The collector electrode of the 6th triode Q6 is as the first output of protective circuit;
The second end of the 18 resistance R 18 is as the second output of protective circuit.
In addition, the transport and placing device in the above embodiments of the present application can be the transport and placing device of various ways, for example: can be: LM2904 transport and placing device.
In addition, the application also provides a kind of constant-current control circuit in another embodiment, referring to Fig. 3, the constant-current control circuit that the present embodiment provides comprises the technical characterictic in above-mentioned all embodiment, because the technical characterictic in the present embodiment is all made respectively detailed introduction in the above-described embodiments, therefore needn't tire out and state.
For convenient, understand, constant-current control circuit the embodiment of the present application being provided at this is made simple introduction: the DCIN in the present embodiment is direct current Source input, DCOUT is constant current output positive pole, LED1, LED2, LED3 and LED4 can be considered as the LED quantity in backlight, wherein the number of LED does not limit, U2 is master control display chip TSUMV59 or MSD3393, R14 is current sampling resistor, the ADC port that sample rate current signal is input to main control chip by R19 carries out analog-to-digital conversion, master control display chip is exported PWM duty cycle signals by the output voltage of drive circuit control BOOST booster circuit (being the power conversion circuit in the application) after pid algorithm calculates, thereby obtain stable output current,
From accompanying drawing 3, the protective circuit in the embodiment of the present application comprises current protection and voltage protection; By the source electrode place of field effect transistor Q2, obtained the output current of power conversion circuit, by the common port of the 7th resistance R 7 and the 13 resistance R 13, obtain the output voltage of power output circuit;
When the output current of power conversion circuit exceedes preset value, transport and placing device U1 output current signal control switch diode output high level in protective circuit, turn-off drive circuit, and, transport and placing device U1 is also sent to current signal master control display chip U1, master control display chip U1 will get after current signal, the predetermined current value of this current signal and current preset constant current rule is compared, output PWM duty cycle signals is to drive circuit, and drive circuit is modulated the output current of power conversion circuit according to PWM duty cycle signals;
As seen from Figure 3, first resistance R 1 in parallel with the second capacitor C 2, the 4th resistance R 4, the resistance pressure-dividing network that the 7th resistance R the 7 and the 13 resistance R 13 forms forms overvoltage crowbar, when the voltage that resistance pressure-dividing network is got is greater than after the reference voltage of comparator of amplifier U1 composition, transport and placing device is exported a high level signal control switch diode forward conducting, control drive circuit turn-offs, and this high level signal is sent to master control display chip, Master control chip U1 gets after high level signal, controlling PWM duty cycle signals reduces, until the output voltage of power output circuit is reduced in normal range (NR).
And, as seen from Figure 3, the 14 resistance R 14 is current sampling resistor, the sample rate current signal of the 14 resistance R 14 is transported to the first input end ADC of master control display chip by the 19 resistance R 19, this current sampling signal is carried out to analog-to-digital conversion, after PID calculates, export PWM duty cycle signals to drive circuit, drive circuit is according to the output current of PWM duty cycle signals modulation power translation circuit.
It should be noted that, the default constant current rule in the application can be directly by obtaining in master control display chip.
The embodiment being provided from the application, the constant-current control circuit that the application provides, utilized the redundant resource of master control display chip, cast out constant-current controller special in prior art, make equipment cost lower, and, realized constant current digitlization, the change of default constant current rule does not need to revise hardware, adopts the constant-current control circuit that the application provides can export multiple constant current value.
In addition, the application also provides a kind of Constant Current Control System backlight, can comprise: the constant-current control circuit in the above-mentioned all embodiment of DC power supply, backlight and the application.
A kind of LCD TV, can comprise: the constant-current control circuit in above-mentioned all embodiment.
Finally, also it should be noted that, in this article, relational terms such as the first and second grades is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply and between these entities or operation, have the relation of any this reality or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thereby the process, method, article or the equipment that make to comprise a series of key elements not only comprise those key elements, but also comprise other key elements of clearly not listing, or be also included as the intrinsic key element of this process, method, article or equipment.The in the situation that of more restrictions not, the key element being limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment that comprises key element and also have other identical element.
In this specification, each embodiment adopts the mode of going forward one by one to describe, and each embodiment stresses is and the difference of other embodiment, between each embodiment identical similar part mutually referring to.
To the above-mentioned explanation of the disclosed embodiments, make professional and technical personnel in the field can realize or use the application.To the multiple modification of these embodiment, will be apparent for those skilled in the art, General Principle as defined herein can, in the case of not departing from the application's spirit or scope, realize in other embodiments.Therefore, the application will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (10)
1. a constant-current control circuit, is characterized in that, comprising:
The power conversion circuit that input is connected with DC power supply, the power take-off of described power conversion circuit is connected with the input of backlight;
The sample circuit that input is connected with the output of backlight;
The master control display chip that first input end is connected with described sample circuit output, for the output current signal of power conversion circuit and the predetermined current value of default constant current rule that described sample circuit is detected by described backlight, compare, and output pulse width modulation signal, in described master control display chip, prestore the default constant current rule of N kind, described N is not less than 1 positive integer;
The drive circuit that input is connected with the output of described master control display chip, described drive circuit output is connected with the power control end of described power conversion circuit.
2. constant-current control circuit according to claim 1, is characterized in that, also comprises:
The protective circuit that first input end is connected with power conversion circuit power take-off; the second input of described protective circuit is connected with the current output terminal of power conversion circuit; the first output of described protective circuit is connected with the protection end of drive circuit, and the second output of described protective circuit is connected with the second input of described master control display chip.
3. constant-current control circuit according to claim 1, is characterized in that, described power conversion circuit comprises:
The inductance that first end is connected with DC power supply;
Anodal the first electric capacity being connected with the first end of described inductance;
The anode diode that is connected with the second end of described inductance;
Anodal the second electric capacity being connected with the negative electrode of described diode and the 3rd electric capacity;
The minus earth of described the first electric capacity, the second electric capacity and the 3rd electric capacity;
The field effect transistor that drain electrode is connected with the second end of described inductance;
The positive pole of described the first electric capacity is as the input of described power conversion circuit;
The negative electrode of described diode is as the power take-off of described power conversion circuit;
The grid of described field effect transistor is as the power control end of described power conversion circuit;
The source electrode of described field effect transistor is as the current output terminal of described power conversion circuit.
4. constant-current control circuit according to claim 1, is characterized in that, described sample circuit comprises:
The 14 resistance of first end ground connection, the second end of described the 14 resistance is connected with the output of described backlight;
The 19 resistance being connected with the second end of described the 14 resistance;
The 7th electric capacity that one end is connected other end ground connection with described the 19 resistance;
The common port of described the 14 resistance and the 19 resistance is as the input of described sample circuit;
The common port of described the 19 resistance and described the 7th electric capacity is as described sample circuit output.
5. constant-current control circuit according to claim 1, is characterized in that, described master control display chip comprises:
TSUMV59 chip or MSD3393 chip;
The ADC port of described TSUMV59 or MSD3393 chip is as the first input end of described master control display chip;
The IO port of described TSUMV59 or MSD3393 chip is as the second input of described master control display chip;
The PWM port of described TSUMV59 or MSD3393 chip is as the output of described master control display chip.
6. constant-current control circuit according to claim 1, is characterized in that, described drive circuit comprises:
The 9th resistance that first end is connected with the output of described master control display chip;
The 11 resistance being connected with described the 9th resistance the second end;
The 5th triode that base stage is connected with described the 9th resistance the second end;
The second resistance that first end is connected with the collector electrode of described the 5th triode;
The 3rd triode that base stage is connected with the collector electrode of described the 5th triode;
The 3rd resistance that first end is connected with described the 3rd transistor emitter;
The 8th resistance that first end is connected with the collector electrode of described the 3rd triode;
The first triode that base stage is connected with the second end of described the 8th resistance and the 4th triode;
The 5th resistance that first end is connected with the emitter of the 4th triode with described the first triode;
The 6th resistance that first end is connected with the second end of described the 5th resistance;
The collector electrode of described the 4th triode, the emitter of the 5th triode, the second end of the 11 resistance and the second end ground connection of the 6th resistance;
The second end, the second end of the 3rd resistance and the collector electrode of the first triode of described the second resistance are connected with power supply VCC;
The first end of described the 9th resistance is as the input of described drive circuit;
The base stage of described the 4th triode is as the protection end of described drive circuit;
The second end of described the 5th resistance is as the output of described drive circuit.
7. constant-current control circuit according to claim 2, is characterized in that, described protective circuit comprises:
The first resistance, the 4th resistance, the 7th resistance, the 20 resistance and the 16 resistance of series connection successively;
The 12 resistance, the 15 resistance and the 17 resistance of series connection successively, one end ground connection that described the 12 resistance is not connected with described the 15 resistance;
The 13 resistance that first end is connected with the common port of the 20 resistance with described the 7th resistance, the second end ground connection of described the 13 resistance;
The switching diode that first input end is connected with one end that described the 16 resistance is not connected with described the 20 resistance;
The tenth resistance that first end is connected with the output of described switching diode;
The 6th triode that base stage is connected with described the tenth resistance the second end;
The 7th resistance that first end is connected with described the tenth resistance the second end;
Four electric capacity in parallel with described the 7th resistance;
One end is connected other end ground connection with described the 17 resistance the 5th electric capacity with the common port of described the 15 resistance;
The 18 resistance that first end is connected with the second input of described switching diode;
One end is connected with the second end of described the 18 resistance, the 8th electric capacity of other end ground connection;
One end that the second input of described switching diode is not connected with the 5th electric capacity with described the 17 resistance is connected;
One end is connected with the 20 resistance common port with described the 16 resistance, the 6th electric capacity of other end ground connection;
The transport and placing device that the first pin is connected with the second input of described switching diode;
The 3rd pin of described transport and placing device is connected with the common port of the 17 resistance with described the 5th electric capacity; The 4th pin ground connection of described transport and placing device; The 5th pin of described transport and placing device is connected with the common port of the 20 resistance with described the 16 resistance; The 7th pin of described transport and placing device is connected with the first input end of described switching diode;
One end not being connected with described the 4th resistance of described the first resistance is as the first input end of described protective circuit;
The common port of described the 15 resistance and the 12 resistance is as the second input of described protective circuit;
The collector electrode of described the 6th triode is as the first output of described protective circuit;
The second end of described the 18 resistance is as the second output of described protective circuit.
8. constant-current control circuit according to claim 7, is characterized in that, described transport and placing device, comprising: LM2904 transport and placing device.
9. a Constant Current Control System backlight, is characterized in that, comprising: the constant-current control circuit in DC power supply, backlight and claim 1-8 any one claim.
10. a LCD TV, is characterized in that, comprising: the constant-current control circuit in claim 1-8 any one claim.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320686280.7U CN203590545U (en) | 2013-10-31 | 2013-10-31 | Constant current control circuit and system and liquid crystal display television |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320686280.7U CN203590545U (en) | 2013-10-31 | 2013-10-31 | Constant current control circuit and system and liquid crystal display television |
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| Publication Number | Publication Date |
|---|---|
| CN203590545U true CN203590545U (en) | 2014-05-07 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201320686280.7U Expired - Lifetime CN203590545U (en) | 2013-10-31 | 2013-10-31 | Constant current control circuit and system and liquid crystal display television |
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| CN (1) | CN203590545U (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104308330A (en) * | 2014-08-13 | 2015-01-28 | 深圳市绿能芯科技有限公司 | Electric welding machine and constant-current control circuit |
| CN105070251A (en) * | 2015-07-22 | 2015-11-18 | Tcl海外电子（惠州）有限公司 | Backlight control method and device |
| TWI576006B (en) * | 2014-09-19 | 2017-03-21 | Light emitting diode controller and method thereof | |
| TWI630841B (en) * | 2017-04-12 | 2018-07-21 | 點晶科技股份有限公司 | Driving circuit and illumination device |
| CN116206570A (en) * | 2021-11-30 | 2023-06-02 | 北京讯通安添通讯科技有限公司 | Screen backlight brightness adjusting method and adjusting system |
-
2013
- 2013-10-31 CN CN201320686280.7U patent/CN203590545U/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104308330A (en) * | 2014-08-13 | 2015-01-28 | 深圳市绿能芯科技有限公司 | Electric welding machine and constant-current control circuit |
| CN104308330B (en) * | 2014-08-13 | 2016-08-17 | 深圳市绿能芯科技有限公司 | A kind of electric welding machine and constant-current control circuit thereof |
| TWI576006B (en) * | 2014-09-19 | 2017-03-21 | Light emitting diode controller and method thereof | |
| CN105070251A (en) * | 2015-07-22 | 2015-11-18 | Tcl海外电子（惠州）有限公司 | Backlight control method and device |
| TWI630841B (en) * | 2017-04-12 | 2018-07-21 | 點晶科技股份有限公司 | Driving circuit and illumination device |
| US10448475B2 (en) | 2017-04-12 | 2019-10-15 | Silicon Touch Technology Inc. | Driving circuit and illumination device |
| CN116206570A (en) * | 2021-11-30 | 2023-06-02 | 北京讯通安添通讯科技有限公司 | Screen backlight brightness adjusting method and adjusting system |
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