CN110049596B - Pulse input detection circuit for white light LED dimming - Google Patents
Pulse input detection circuit for white light LED dimming Download PDFInfo
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- CN110049596B CN110049596B CN201910348987.9A CN201910348987A CN110049596B CN 110049596 B CN110049596 B CN 110049596B CN 201910348987 A CN201910348987 A CN 201910348987A CN 110049596 B CN110049596 B CN 110049596B
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- 238000001514 detection method Methods 0.000 title claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- 239000003990 capacitor Substances 0.000 claims description 23
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
Classifications
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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]
- H05B45/10—Controlling the intensity of the light
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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]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
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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
The invention provides a pulse input detection circuit for dimming a white light LED, which is characterized in that a level conversion circuit and a voltage division network circuit powered by a reference voltage are added in front of a traditional pulse low-pass filter. When a pulse signal for changing the brightness of the white light LED is required to be provided, the direct-current voltage signal in linear and proportional relation with the duty ratio of the input pulse signal can be obtained only by setting the duty ratio information of the pulse signal and without changing the high-level voltage of the pulse signal, so that the level range of the input pulse signal is greatly widened, the requirement on the output level of a front-stage circuit is reduced, and the direct-current voltage signal has universality.
Description
Technical Field
The invention relates to the field of circuits, in particular to a pulse input detection circuit.
Background
White light LEDs are required to change their brightness according to the environment in applications such as cell phones, tablet computers, and various portable multimedia player screens. The present white LED driver chip generally designs a Ctrl pin for detecting an input pulse signal. The purpose of adjusting the current flowing through the LED is achieved by changing the high level and the duty ratio of the pulse signal and converting the pulse signal through the LED driving chip. However, since the pulse signal with duty ratio information is generally generated by the front-end circuit of the LED driver chip, the high level of the pulse signal has a certain value in some applications, which is inconvenient to change the voltage level, and limits the application of the pulse detection method.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a pulse input detection circuit for dimming a white light LED.
The technical scheme adopted for solving the technical problems is as follows:
a pulse input detection circuit for white light LED dimming comprises a band gap reference circuit, a buffer circuit, an inverter circuit, a PMOS tube M1, an NMOS tube M2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2; the bandgap reference circuit generates a reference voltage VREF and inputs the reference voltage VREF to the buffer circuit; the buffer circuit outputs a voltage signal V1; the grid electrode of the PMOS tube M1 is connected with the grid electrode of the NMOS tube M2, the source electrode of the PMOS tube M1 is connected with the voltage V1, the drain electrode of the PMOS tube M1 is connected with the drain electrode of the NMOS tube M2, the source electrode of the NMOS tube M2 is grounded, the M1 tube and the M2 tube form a level conversion circuit, and the voltage signal V1 is used as a power signal of the level conversion circuit; the inverter circuit shapes the pulse input signal into a square wave signal V2, and the square wave signal V2 is output to the grid electrodes of the M1 pipe and the M2 pipe; the level conversion circuit formed by the M1 pipe and the M2 pipe converts the square wave signal V2 into a pulse signal V3, wherein the high level value of the pulse signal V3 is a voltage value of V1, and the voltage value is output from a drain electrode connecting point of the M1 pipe and the M2 pipe; the voltage V3 is connected with one end of the resistor R1, the other end of the resistor R1 is connected with one end of the resistor R2, the other end of the resistor R2 is connected with the ground, the resistor R1 and the resistor R2 form a voltage dividing circuit, the pulse signal V3 is divided, and a divided signal V4 is output at the connecting point of the resistor R1 and the resistor R2; one end of a resistor R3 is connected with a voltage V4, and the other end of the resistor R3 is respectively connected with one end of a capacitor C1 and one end of the resistor R4; the other end of the capacitor C1 is connected with the ground; the other end of the resistor R4 is connected with one end of the capacitor C2; the other end of the capacitor C2 is connected with the ground; the resistor R3, the capacitor C1, the resistor R4 and the capacitor C2 form a two-stage low-pass filter, the signal V4 is filtered, the direct current level Vdc is output from the other end of the resistor R4, and the signal of the current flowing through the LED is controlled.
The invention has the beneficial effects that the level conversion circuit and the voltage dividing network circuit which are powered by the reference voltage are added before the traditional pulse low-pass filter. When a pulse signal for changing the brightness of the white light LED is required to be provided, the direct-current voltage signal in linear and proportional relation with the duty ratio of the input pulse signal can be obtained only by setting the duty ratio information of the pulse signal and without changing the high-level voltage of the pulse signal, so that the level range of the input pulse signal is greatly widened, the requirement on the output level of a front-stage circuit is reduced, and the direct-current voltage signal has universality.
Drawings
FIG. 1 is a block diagram of an embodiment of a detection circuit of the present invention.
Detailed Description
The invention will be further described with reference to the drawings and examples.
As shown in fig. 1, a pulse input detection circuit for dimming a white LED includes a bandgap reference circuit, including a bandgap reference circuit, a buffer circuit, an inverter circuit, a PMOS transistor M1, an NMOS transistor M2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, and a capacitor C2; the bandgap reference circuit generates a reference voltage VREF and inputs the reference voltage VREF to the buffer circuit; the buffer circuit outputs a voltage signal V1; the grid electrode g of the PMOS tube M1 is connected with the grid electrode g of the NMOS tube M2, the source electrode s of the PMOS tube M1 is connected with the voltage V1, the drain electrode d of the PMOS tube M1 is connected with the drain electrode d of the NMOS tube M2, the source electrode s of the NMOS tube M2 is grounded, the M1 tube and the M2 tube form a level conversion circuit, and the voltage signal V1 is used as a power signal of the level conversion circuit; the inverter circuit shapes the pulse input signal into a square wave signal V2, and the square wave signal V2 is output to the grid electrodes g of the M1 pipe and the M2 pipe; the level conversion circuit formed by the M1 pipe and the M2 pipe converts the square wave signal V2 into a pulse signal V3, wherein the high level value of the pulse signal V3 is the voltage value of V1, and the voltage value is output from the d connecting point of the drains of the M1 pipe and the M2 pipe; the voltage V3 is connected with one end a of the resistor R1, the other end b of the resistor R1 is connected with one end c of the resistor R2, the other end e of the resistor R2 is connected with the ground, the resistor R1 and the resistor R2 form a voltage dividing circuit, the pulse signal V3 is divided, and a divided signal V4 is output at a connecting point of the resistor R1 and the resistor R2; one end f of the resistor R3 is connected with the voltage V4, and the other end h of the resistor R3 is respectively connected with one end j of the capacitor C1 and one end m of the resistor R4; the other end k of the capacitor C1 is connected with the ground; the other end n of the resistor R4 is connected with one end p of the capacitor C2; the other end q of the capacitor C2 is connected with the ground; the resistor R3, the capacitor C1, the resistor R4 and the capacitor C2 form a two-stage low-pass filter, the signal V4 is filtered, the direct current level Vdc is output from the other end n of the resistor R4, and the signal of the current flowing through the LED is controlled.
As shown in fig. 1, the working flow of the detection circuit of the present invention is: the external pulse signal is input into an inverter circuit, and after the inverter circuit shapes the input pulse, the inverter circuit outputs a signal V2; the V2 signal is input into a level conversion circuit consisting of a PMOS tube M1 and an NMOS tube M2. The bandgap reference circuit generates a bandgap reference voltage VREF; the bandgap reference voltage VREF is input into a buffer circuit, and the buffer circuit outputs a voltage signal V1; the voltage signal V1 is connected with the source electrode of the PMOS tube M1 and is used as the power supply voltage of the level converter; when (when)After the V2 signal is converted by the level converter, the high level voltage of the output pulse signal V3 is converted into a level V1; the voltage signal V3 is connected to a voltage division network consisting of a resistor R1 and a resistor R2; the product of the level V1 and the voltage dividing ratio of the voltage dividing network is the DC level Vdc obtained when the pulse signal inputs the hundred percent duty ratio, namelyThe voltage division pulse signal V4 output by the voltage division network passes through a two-stage low-pass filter consisting of a resistor R3, a capacitor C1, a resistor R4 and a capacitor C2 to obtain a direct current level signal Vdc; the relationship between the magnitude of the direct current level signal Vdc and the duty ratio of the input pulse signal can be expressed by the formula: />Where dc_pulse is the duty cycle size of the externally input pulse signal. The magnitude of the DC level signal Vdc outputted at this time is irrelevant to the high level of the externally inputted pulse signal and is only in a proportional relation with the magnitude of the pulse duty ratio, so that the level requirement on the output pulse signal of the front-stage circuit can be reduced, and the application range of the pulse input detection circuit is widened.
Claims (1)
1. The utility model provides a pulse input detection circuitry for white light LED adjusts luminance, includes band gap reference circuit, buffer circuit, inverter circuit, PMOS pipe M1, NMOS pipe M2, resistance R1, resistance R2, resistance R3, resistance R4, electric capacity C1 and electric capacity C2, its characterized in that:
the pulse input detection circuit for white light LED dimming is characterized in that a band gap reference circuit generates a reference voltage VREF and inputs the reference voltage VREF to a buffer circuit: the buffer circuit outputs a voltage signal V1, wherein the grid electrode of the PMOS tube M1 is connected with the grid electrode of the NMOS tube M2, the source electrode of the PMOS tube M1 is connected with the voltage V1, the drain electrode of the PMOS tube M1 is connected with the drain electrode of the NMOS tube M2, the source electrode of the NMOS tube M2 is grounded, the MI tube and the M2 tube form a level conversion circuit, the voltage signal V1 is used as a power signal of the level conversion circuit, the inverter circuit shapes a pulse input signal into a square wave signal V2, the square wave signal V2 is output to the grid electrodes of the M1 tube and the M2 tube, the level conversion circuit formed by the M1 tube and the M2 tube converts the square wave signal V2 into a pulse signal V3, wherein the high level value of the pulse signal V3 is the voltage value of V1, one end of a resistor R1 is connected with the output from the drain electrode connection point of the M1 tube and the M2 tube, the other end of the resistor R1 is connected with one end of the resistor R2, the other end of the resistor R2 is connected with the ground, the other end of the resistor R1 and the resistor R4 are connected with one end of the resistor R4 after the voltage division circuit and the resistor R2 are connected with the other end of the resistor R4 respectively; the other end of the capacitor C1 is connected with the ground, the other end of the resistor R4 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with the ground, the resistor R3, the capacitor C1, the resistor R4 and the capacitor C2 form a two-stage low-pass filter, the voltage V4 is filtered, the direct-current level Vdc is output from the other end of the resistor R4, and the signal of the current flowing through the LED is controlled.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910348987.9A CN110049596B (en) | 2019-04-28 | 2019-04-28 | Pulse input detection circuit for white light LED dimming |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910348987.9A CN110049596B (en) | 2019-04-28 | 2019-04-28 | Pulse input detection circuit for white light LED dimming |
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| CN110049596A CN110049596A (en) | 2019-07-23 |
| CN110049596B true CN110049596B (en) | 2024-02-20 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110706668A (en) * | 2019-09-18 | 2020-01-17 | 深圳市华星光电技术有限公司 | GOA circuit driving system and display device |
| CN114040180B (en) * | 2020-08-26 | 2023-07-25 | 苏州中科全象智能科技有限公司 | Projection brightness control method for 3D structured light camera |
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| CN107426871A (en) * | 2017-08-04 | 2017-12-01 | 欧普照明股份有限公司 | A kind of signaling conversion circuit, dimming LED (Light Emitting Diode) driving power and light fixture |
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Address after: B201, zero one square, Xi'an Software Park, 72 Keji 2nd Road, high tech Zone, Xi'an City, Shaanxi Province, 710000 Applicant after: Tuoer Microelectronics Co.,Ltd. Address before: B201, zero one square, Xi'an Software Park, 72 Keji 2nd Road, high tech Zone, Xi'an City, Shaanxi Province, 710000 Applicant before: Xi'an Tuoer Microelectronics Co.,Ltd. Address after: B201, zero one square, Xi'an Software Park, 72 Keji 2nd Road, high tech Zone, Xi'an City, Shaanxi Province, 710000 Applicant after: Xi'an Tuoer Microelectronics Co.,Ltd. Address before: B201, zero one square, Xi'an Software Park, 72 Keji 2nd Road, high tech Zone, Xi'an City, Shaanxi Province, 710000 Applicant before: XI'AN TUOER MICROELECTRONICS Co.,Ltd. |
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