CN106658823B - A kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control - Google Patents
A kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control Download PDFInfo
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- CN106658823B CN106658823B CN201610976720.0A CN201610976720A CN106658823B CN 106658823 B CN106658823 B CN 106658823B CN 201610976720 A CN201610976720 A CN 201610976720A CN 106658823 B CN106658823 B CN 106658823B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Abstract
A kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control, circuit include it is more than two with LED lamp bead one-to-one correspondence and with the electronic switch of corresponding LED lamp bead parallel connection and the driver be connected for controlling electronic switch；The electronic switch is N-channel MOS pipe, and the drain electrode of the N-channel MOS pipe and the anode of LED lamp bead connect, and the source electrode of N-channel MOS pipe and the cathode of LED lamp bead connect, and driver controls the grid of N-channel MOS pipe by pwm signal；The circuit carries out brightness adjustment control according to following logic.Multiple LED lamp beads are cascaded, and are driven with constant-current source all the way, an electronic switch in parallel again in every LED lamp bead, so that it may accomplish that every LED lamp bead is individually lighted or extinguished.As long as the switching speed of electronic switch is sufficiently fast, the average current for flowing through every LED lamp bead can be adjusted by adjusting the duty ratio in each electronic switch period, to control the output power of each LED pixel point, the independent light on and off and light modulation of every LED lamp bead are realized.
Description
Technical field
The present invention relates to LED illumination lamp field more particularly to a kind of multiple LED pixel points of single channel constant current drive control
Circuit brightness adjustment control logic.
Background technique
LED illumination lamp on the market at present, most of is all to drive LED with constant-current drive circuit and adjust LED to drive
Streaming current, constant current driving in general 1 tunnel can only drive 1 paths of LEDs lamp string, and LED multi-path lamp string just needs multi-path constant-current drive circuit.
This constant current drive scheme must use multi-path constant-current drive circuit when being used in control Matrix LED pixel, and N number of pixel just needs
N number of constant-current drive circuit, just seeming to compare takes up space and higher cost.
Summary of the invention
Technical problem to be solved by the invention is to provide a kind of circuits of the multiple LED pixel points of single channel constant current drive control
Brightness adjustment control logic reduces the cost of LED lattice pixels driving circuit and simplifies circuit structure.
In order to solve the above technical problems, the technical scheme is that a kind of multiple LED pixels of single channel constant current drive control
The circuit brightness adjustment control logic of point further includes for driving including being serially connected the LED light string formed by more than two LED lamp beads
Move the logic control circuit of the LED light string, the logic control circuit include it is more than two corresponded with LED lamp bead and with
The electronic switch of corresponding LED lamp bead parallel connection and the driver be connected for controlling electronic switch；The electronic switch is N-channel
Metal-oxide-semiconductor, the drain electrode of the N-channel MOS pipe and the anode of LED lamp bead connect, the source electrode of N-channel MOS pipe and the cathode of LED lamp bead
Connection, driver control the grid of N-channel MOS pipe by pwm signal；The circuit carries out brightness adjustment control according to following logic:
(1) pwm pulse timing is asynchronous；
(2) there are fixed phase drifts for pwm pulse sequential logic；
(3) PWM sequential logic phase shift interval t=T/n；
PWM switch motion all the way is only filled perhaps within a very small period.
Multiple LED lamp beads are cascaded, and are driven with constant-current source all the way, an electronics in parallel again in every LED lamp bead
Switch, so that it may accomplish that every LED lamp bead is individually lighted or extinguished.As long as the switching speed of electronic switch is sufficiently fast, so that it may
To adjust the average current for flowing through every LED lamp bead by the duty ratio for adjusting each electronic switch period, so that control is every
The output power of a LED pixel point realizes the independent light on and off and light modulation of every LED lamp bead.
As an improvement, the driver is half-bridge driver.
As an improvement, the grid of N-channel MOS pipe and the cut-in voltage at source electrode both ends are Vgs, high side LED lamp bead the two poles of the earth pair
The voltage of GND is Vdg；When Vdg is greater than the supply voltage VDD of half-bridge driver, half-bridge driver is by high side N-channel MOS pipe
Vgs voltage raise.
As an improvement, when all light of LED light string, if the cathode voltage of LED lamp bead is plus its N-channel MOS pipe in parallel
Conducting voltage is greater than the voltage value of VDD, then the grid of N-channel MOS in parallel is connected to the upper bridge end of half-bridge driver.
As an improvement, the upper bridge of half-bridge driver, which is driven through bootstrap capacitor C1 and bootstrap diode D1, makes half-bridge driver
The voltage value of pin HB remain that the voltage than pin HS is higher by the voltage value of a Vgs, pin HS respectively with N-channel
The source electrode of metal-oxide-semiconductor is connected with the cathode of corresponding high side LED lamp bead；If the pin HI of half-bridge driver exports high level at this time,
The pin HO that half-bridge driver is connect with the grid of N-channel MOS pipe then exports the voltage of HB；The lower bridge output of half-bridge driver is straight
It connects and is powered by VDD, if the pin LI of half-bridge driver exports high level, half-bridge driver N-channel corresponding with downside LED lamp bead
The pin LO of metal-oxide-semiconductor grid connection then exports the voltage of VDD, guarantees that the voltage value of VDD has to be larger than the conducting of N-channel MOS pipe
Voltage.
As an improvement, when pin HI exports high level, signal after the Bootstrap of the upper bridge of half-bridge driver
N-channel MOS, the conducting of N-channel MOS pipe are accessed, corresponding lamp bead LED lamp bead does not work；When pin HI exports low level, half-bridge is driven
Dynamic device is failure to actuate, and N-channel MOS pipe is not turned on, corresponding LED lamp bead all light；Then pass through the duty ratio of adjustment pin HI high level
It is flowed through to adjust the duty ratio of half-bridge driver output signal to adjust the turn-on time in N-channel MOS each period to change
The average current size of corresponding LED lamp bead.
The beneficial effect of the invention compared with the existing technology is:
Multiple LED lamp beads are cascaded, and are driven with constant-current source all the way, an electronics in parallel again in every LED lamp bead
Switch, so that it may accomplish that every LED lamp bead is individually lighted or extinguished；As long as the switching speed of electronic switch is sufficiently fast, so that it may
To adjust the average current for flowing through every LED lamp bead by the duty ratio for adjusting each electronic switch period, so that control is every
The output power of a LED pixel point, realizes the independent light on and off and light modulation of every LED lamp bead, i.e. single channel constant current drive control is multiple
LED pixel point reduces the cost of LED lattice pixels driving circuit and simplifies circuit structure.
Detailed description of the invention
Fig. 1 is logical circuitry of the present invention.
Fig. 2 is application circuit of the present invention.
Fig. 3 is asynchronous fixed phase drift PWM sequential logic figure.
Specific embodiment
The invention is further explained in the following combination with the attached drawings of the specification.
As shown in Figure 1, a kind of circuit of the multiple LED pixel points of single channel constant current drive control, including by more than two LED light
Pearl is serially connected the LED light string of composition and the logic control circuit for driving the LED light string.As shown in Fig. 2, the present embodiment
LED light string be made of six LED lamp beads, be LED1-LED6 respectively, wherein LED1-LED3 be high side LED lamp bead, LED4-
LED6 is downside LED lamp bead；Each LED lamp bead is a pixel, also can be set according to actual needs the quantity of pixel.
The logic control circuit includes six and corresponds and the electronic switch in parallel with corresponding LED lamp bead and be used for LED lamp bead
Control the driver of electronic switch conducting；In the present embodiment, electronic switch selects N-channel MOS pipe Q1-Q6 to replace, and selects
Three half-bridge driver U1-U3 drive N-channel MOS to be connected, and half-bridge driver output signal is controlled with pwm signal.
Guarantee N-channel MOS pipe normal switch, must just be added and open in the grid G of N-channel MOS pipe and source S both ends
Voltage Vgs, general Vgs > 5 ~ 10V.But there are PN junction voltage Vf, Vf=3 ~ 4V for LED chip itself；With the increasing of LED serial number
Add, high side LED lamp bead the two poles of the earth also correspondingly increase GND voltage Vdg, when Vdg is greater than half-bridge driven supply voltage VDD, with regard to nothing
Method guarantees N-channel MOS pipe grid source plate voltage Vgs, and the N-channel MOS pipe of high side can not be normally-open, this just needs to drive using half-bridge
Dynamic circuit raises the Vgs voltage of the N-channel MOS pipe of high side.
As shown in Fig. 2, the upper bridge driving of half-bridge driver U1 can make pin by bootstrap capacitor C1 and bootstrap diode D1
The voltage value of HB remains that the voltage (i.e. the S pole tension of N-channel MOS pipe Q1) than pin HS is higher by the voltage value of a Vgs,
If at this time PWM6 export high level, the pole G of pin HO(N channel MOS tube Q1) output pin HB voltage.Half-bridge driver U1
Lower bridge output directly powered by VDD, if PWM3 export high level, the pole G of pin LO(N channel MOS tube Q4) export VDD's
Voltage, so the voltage value of VDD has to be larger than the conducting voltage of N-channel MOS pipe.When LED pixel point all light, if LED lamp bead
Cathode voltage is greater than the voltage value of VDD plus the conducting voltage of its N-channel MOS pipe in parallel, just must be N-channel MOS in parallel
The pole G of pipe is connected to the upper bridge end of half-bridge driver.
As shown in Fig. 2, when the PWM6 of half-bridge driver U1 exports high level, by the bootstrapping of bridge on half-bridge driver U1
Signal is accessed N-channel MOS pipe Q1, N-channel MOS pipe Q1 conducting after boosting, lamp bead LED1 does not work；When PWM6 exports low level
When, half-bridge driver U1 is failure to actuate, and N-channel MOS pipe Q1 is not turned on, lamp bead LED1 all light.It can be by adjusting PWM6 high level
Duty ratio is come when adjusting conducting of the duty ratio of half-bridge driver U1 output signal to adjust N-channel MOS pipe Q1 each period
Between change the average current size for flowing through lamp bead LED1.Other five LED lamp beads are also similarly to control, to realize with one
Road constant-current drive circuit drives six LED and every LED can individually adjust its electric current.
For the electrical characteristic of the circuit of the multiple LED pixel points of single channel constant current drive control, a kind of feasible light modulation is provided
Control logic scheme: thinking of the invention is that PWM switch motion all the way is only filled perhaps within a very small period, is ensured that
There was only a LED under the premise of minimum switch conduction times, on route is conducting, and guarantees every two adjacent pulse
Time interval is much larger than the time of switching pulse, and the output power of time circuit same in this way is provided only to a LED, output electricity
Pressure and electric current are all stable.Electrical control logic chart is spaced between every road PWM as shown in figure 3, every road PWM duty cycle is T
Time is t=T/n, time-interval averaging distribution.
The PWM sequential logic of asynchronous fixed phase drift has 4 essential characteristics:
1, pwm pulse timing is asynchronous.It ensure that in minimum turn-on time, circuit can provide enough power to maintain one
LED electric current.
2, there are fixed phase drifts for pwm pulse sequential logic.The distance between widen and guarantee burst pulse, there is circuit enough
Time respond next pulse.The response time for being averagely allocated to every LED is identical.
3, PWM sequential logic phase shift interval t=T/n.It ensure that the characteristic of each switch is consistent, distribute each LED all
To equal output power.
4, PWM switch motion all the way is only filled perhaps within a very small period.
When pwm pulse width W is much larger than the duty cycle 2us of circuit, circuit has had enough response times (very much
A period) output power required for circuit is provided, the interference constant-current circuit that switching pulse is formed has sufficient time to do
Adjustment.
Claims (6)
1. a kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control, including by more than two LED light
Pearl is serially connected the LED light string of composition, it is characterised in that: further includes the logic control circuit for driving the LED light string, institute
Stating logic control circuit includes two or more and LED lamp bead one-to-one correspondence and the electronic switch and use in parallel with corresponding LED lamp bead
In the driver of control electronic switch conducting；The electronic switch is N-channel MOS pipe, the drain electrode of the N-channel MOS pipe and LED
The anode of lamp bead connects, and the source electrode of N-channel MOS pipe and the cathode of LED lamp bead connect, and driver controls N-channel by pwm signal
The grid of metal-oxide-semiconductor；The logic control circuit carries out brightness adjustment control according to following logic:
(1) pwm pulse timing is asynchronous；
(2) there are fixed phase drifts for pwm pulse sequential logic；
(3) PWM sequential logic phase shift interval t=T/n；
(4) PWM switch motion all the way is only filled perhaps within a very small period.
2. a kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control according to claim 1,
It is characterized by: the driver is half-bridge driver.
3. a kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control according to claim 2,
It is characterized by: the grid of N-channel MOS pipe and the cut-in voltage at source electrode both ends are Vgs, electricity of the high side LED lamp bead the two poles of the earth to GND
Pressure is Vdg；When Vdg is greater than the supply voltage VDD of half-bridge driver, half-bridge driver is electric by the Vgs of high side N-channel MOS pipe
Pressure is raised.
4. a kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control according to claim 3,
It is characterized by: when all light of LED light string, if the cathode voltage of LED lamp bead is plus the electric conduction of its N-channel MOS pipe in parallel
Pressure is greater than the voltage value of VDD, then the grid of N-channel MOS in parallel is connected to the upper bridge end of half-bridge driver.
5. a kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control according to claim 4,
It is characterized by: the upper bridge of half-bridge driver, which is driven through bootstrap capacitor C1 and bootstrap diode D1, makes the pin of half-bridge driver
The voltage value of HB remains that the voltage than pin HS is higher by the voltage value of a Vgs, pin HS respectively with N-channel MOS pipe
Source electrode is connected with the cathode of corresponding high side LED lamp bead；If the pin HI of half-bridge driver exports high level, half-bridge driven at this time
The pin HO that device is connect with the grid of N-channel MOS pipe then exports the voltage of HB；The lower bridge of half-bridge driver exports directly by VDD
Power supply, if the pin LI of half-bridge driver exports high level, half-bridge driver N-channel MOS pipe grid corresponding with downside LED lamp bead
The pin LO of pole connection then exports the voltage of VDD, guarantees that the voltage value of VDD has to be larger than the conducting voltage of N-channel MOS pipe；
Pin HI and pin LI is separately connected PWM light modulation input terminal；One end of the bootstrap capacitor of pin HB connection half-bridge driver
And booster diode；The grid G of the N-channel switch metal-oxide-semiconductor at the both ends pin HO connection high side LED；Pin LO connection downside LED two
The grid G of the N-channel switch metal-oxide-semiconductor at end；The source S and bootstrapping of the N-channel switch metal-oxide-semiconductor at the both ends pin HS connection high side LED
The other end of capacitor.
6. a kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control according to claim 5,
It is characterized by: signal is accessed N ditch after the Bootstrap of the upper bridge of half-bridge driver when pin HI exports high level
Road MOS, the conducting of N-channel MOS pipe, corresponding lamp bead LED lamp bead do not work；When pin HI exports low level, half-bridge driver is not
Movement, N-channel MOS pipe are not turned on, corresponding LED lamp bead all light；Then adjusted by the duty ratio of adjustment pin HI high level
The duty ratio of half-bridge driver output signal flows through corresponding LED to adjust the turn-on time in N-channel MOS each period to change
The average current size of lamp bead.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610976720.0A CN106658823B (en) | 2016-11-08 | 2016-11-08 | A kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control |
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| CN201610976720.0A CN106658823B (en) | 2016-11-08 | 2016-11-08 | A kind of circuit brightness adjustment control logic of the multiple LED pixel points of single channel constant current drive control |
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| CN107493635A (en) * | 2017-09-22 | 2017-12-19 | 浙江晶日照明科技有限公司 | A kind of more pixel drive systems of LED |
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| CN108684112A (en) * | 2018-07-27 | 2018-10-19 | 杭州旗翔光电科技有限公司 | A kind of distribution-adjustable light than LED plant lamps |
| CN109121258A (en) * | 2018-10-12 | 2019-01-01 | 青岛亿联客信息技术有限公司 | A kind of light-dimming method and dimming device |
| CN110213864A (en) * | 2019-07-15 | 2019-09-06 | 上海阿卡得电子有限公司 | The device of single channel light modulation shutdown power supply circuit control multiple-channel output light adjusting circuit |
| CN113498234B (en) * | 2020-04-01 | 2023-05-12 | 炬芯科技股份有限公司 | MOS tube driving circuit and enhanced LED driving circuit |
| CN112235905A (en) * | 2020-10-23 | 2021-01-15 | 青岛易来智能科技股份有限公司 | Brightness adjusting circuit, lamp and LED brightness control method |
| CN115734416B (en) * | 2022-10-18 | 2023-09-19 | 深圳市美矽微半导体有限公司 | LED wide voltage self-adaptive control method, control circuit and display device |
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