CN103796399A - Undistorted LED PWM luminance control circuit - Google Patents
Undistorted LED PWM luminance control circuit Download PDFInfo
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- CN103796399A CN103796399A CN201410081380.6A CN201410081380A CN103796399A CN 103796399 A CN103796399 A CN 103796399A CN 201410081380 A CN201410081380 A CN 201410081380A CN 103796399 A CN103796399 A CN 103796399A
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- led
- pwm
- pwm signal
- undistorted
- drive current
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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
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
Abstract
The invention discloses an undistorted LED PWM control circuit. The undistorted LED PWM luminance control circuit comprises an LED constant current driver, a PWM signal generating circuit, a switching tube Q1, a comparator Com1 and a digital control module. By means of the undistorted LED PWM luminance control circuit, PWM constant current output loss can be corrected, the integrity of LED constant current output signals can be kept, and LED luminance distortion is avoided.
Description
Technical field
The present invention relates to LED illumination control circuit, be specifically related to a kind of undistorted LED PWM intednsity circuit.
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Background technology
Nowadays, LED is the perfect light source of acting on behalf of conventional light source, and its power consumption is very low, and electricity conversion is high, becomes the focus in photo field, and regulates LED brightness to have following three kinds of common methods:
The one, use SET resistance, drive and control the in parallel different transfer resistance in IC pin RSET two ends at LED, use a direct voltage that LED is set and drive the electric current of controlling IC pin RSET, thereby change the forward operating current of LED, reach the object that regulates ALED luminosity; The 2nd, linear regulation; The 3rd, adopt PWM technology, utilize pwm control signal, recently regulate the luminosity of ALED by controlling the duty of forward operating current of LED.
But adopt first method dimming controlling method to lack flexibility, cannot allow user change luminous intensity.Linear regulation can lower efficiency, and causes the color offset of white light LEDs towards yellow spectrum, and the simulation light modulation meeting of linear regulation reduces the precision of output current;
And adopt numeral or cry the LED brightness adjustment control method of PWM to be greater than the switch frequency of 100HZ, the pulse duty factor that changes LED drive current with the method for pulse-width modulation is carried out real brightness adjustment control of managing LED, can avoid human eye perceives to arrive light modulation scintillation, light modulation is larger than scope.Therefore, PWM control technology is controlled simple with it, flexibly and the good advantage of dynamic response and become the control mode that is widely used in LED most.
LED is carried out under the background of brightness regulation in use PWM control technology, traditional LED driver is LED constant-flow driver, it is according to PWM output driving current, but due to the constraint of internal drive dynamic corresponding time, constant-flow driver firing current can be than the slow certain hour of pwm signal, close simultaneously, therefore can cause the switching tube opening time fewer than the actual PWM control time, cause driving current signal loss.In addition, adopt the constant-flow driver Acceleration of starting method of simulation can only reduce the loss of pwm signal, but can not eliminate the impact of this effect completely, and need to pay the cost of chip area (cost) and power consumption aspect.
Summary of the invention
The weak point existing in order to solve prior art, the invention provides a kind of undistorted LED PWM intednsity circuit, and it can proofread and correct the loss of PWM constant current output, makes LED constant current output signal keep complete, makes LED brightness undistorted.
The technical solution used in the present invention is as follows:
A kind of undistorted LED PWM intednsity circuit, comprises LED constant-flow driver, pwm signal circuit for generating, switching tube Q1, comparator C om1 and digital control module; Described LED constant-flow driver is for generation of drive current Iled; Described pwm signal circuit for generating is for generation of pwm signal, and controls LED constant-flow driver and produce drive current Iled; Described switching tube Q1 is for controlling the unlatching of drive current Iled, and when pwm signal is while being high, the drive current Iled of switching tube Q1 opens, and when pwm signal is while being low, the drive current Iled of switching tube Q1 closes; Described comparator C om1 is used for obtaining driving current signal and it is extracted as to Vled signal, relatively obtains in real time actual switch pipe Q1 opening time difference dT; Described digital control module is electrically connected with comparator C om1, for obtaining opening time difference dT, and time difference dT is added to the loss that starts with correcting switch pipe Q1 in pwm signal.
The beneficial effect that the present invention compared with prior art has: the present invention adopts digital signal processing module to proofread and correct the loss of PWM constant current output, makes LED constant current output signal keep complete.
Accompanying drawing explanation
Fig. 1: circuit theory diagrams of the present invention;
Fig. 2: time difference compensation principle figure of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.
As shown in Figure 1, a kind of undistorted LED PWM intednsity circuit, comprises LED constant-flow driver, pwm signal circuit for generating, switching tube Q1, comparator C om1 and digital control module; Described LED constant-flow driver is for generation of drive current Iled; Described pwm signal circuit for generating is for generation of pwm signal, and controls LED constant-flow driver and produce drive current Iled; Described switching tube Q1 is for controlling the unlatching of drive current Iled, and when pwm signal is while being high, the drive current Iled of switching tube Q1 opens, and when pwm signal is while being low, the drive current Iled of switching tube Q1 closes; Described comparator C om1 is used for obtaining driving current signal and it is extracted as to Vled signal, relatively obtains in real time actual switch pipe Q1 opening time difference dT; Described digital control module is electrically connected with comparator C om1, for obtaining opening time difference dT, and time difference dT is added to the loss that starts with correcting switch pipe (Q1) in pwm signal.
As shown in Figure 2, can see by elongating pwm signal, new Iled2 signal and pwm signal are occurred simultaneously, and now circuit does not have PWM gradation loss.
Claims (1)
1. a undistorted LED PWM intednsity circuit, is characterized in that, comprises LED constant-flow driver, pwm signal circuit for generating, switching tube (Q1), comparator (Com1) and digital control module;
Described LED constant-flow driver is for generation of drive current (Iled);
Described pwm signal circuit for generating is for generation of pwm signal, and controls LED constant-flow driver and produce drive current (Iled);
Described switching tube (Q1) is for controlling the unlatching of drive current (Iled), and when pwm signal is while being high, the drive current (Iled) of switching tube (Q1) is opened, and when pwm signal is while being low, the drive current (Iled) of switching tube (Q1) is closed;
Described comparator (Com1), for obtaining driving current signal and it being extracted as to Vled signal, relatively obtains actual switch pipe (Q1) opening time difference (dT) in real time;
Described digital control module is electrically connected with comparator (Com1), for obtaining opening time difference (dT), and time difference (dT) is added to the loss that starts with correcting switch pipe (Q1) in pwm signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410081380.6A CN103796399A (en) | 2014-03-07 | 2014-03-07 | Undistorted LED PWM luminance control circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410081380.6A CN103796399A (en) | 2014-03-07 | 2014-03-07 | Undistorted LED PWM luminance control circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103796399A true CN103796399A (en) | 2014-05-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410081380.6A Pending CN103796399A (en) | 2014-03-07 | 2014-03-07 | Undistorted LED PWM luminance control circuit |
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| Country | Link |
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| CN (1) | CN103796399A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112673710A (en) * | 2018-09-11 | 2021-04-16 | 罗姆股份有限公司 | LED drive device, illumination device, and in-vehicle display device |
| CN114187882A (en) * | 2021-11-24 | 2022-03-15 | 当趣网络科技(杭州)有限公司 | System and method for adjusting brightness of display screen of projector |
-
2014
- 2014-03-07 CN CN201410081380.6A patent/CN103796399A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112673710A (en) * | 2018-09-11 | 2021-04-16 | 罗姆股份有限公司 | LED drive device, illumination device, and in-vehicle display device |
| CN112673710B (en) * | 2018-09-11 | 2023-08-29 | 罗姆股份有限公司 | LED driving device, lighting device and vehicle-mounted display device |
| CN114187882A (en) * | 2021-11-24 | 2022-03-15 | 当趣网络科技(杭州)有限公司 | System and method for adjusting brightness of display screen of projector |
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| PB01 | Publication | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20140514 |