CN109302771B - LED constant current driving module - Google Patents
LED constant current driving module Download PDFInfo
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- CN109302771B CN109302771B CN201811234174.9A CN201811234174A CN109302771B CN 109302771 B CN109302771 B CN 109302771B CN 201811234174 A CN201811234174 A CN 201811234174A CN 109302771 B CN109302771 B CN 109302771B
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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]
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Abstract
The invention relates to an LED constant current driving module, which comprises an error amplifier, a first switch, a second switch and a signal stabilizing module, wherein the error amplifier is connected with the first switch; a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming resistor; a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier; the signal stabilizing module is connected with a signal output end of the error amplifier, when a dimming signal input end of the error amplifier is at a high level, the error amplifier controls the first switch to be switched on and controls the second switch to be switched off, and the signal stabilizing module outputs a first constant signal.
Description
Technical Field
The invention relates to a dimming device, in particular to an LED constant current driving module.
Background
With the progress of science and technology, the dimming requirements of LED lamps and laser LED lamps become more and more obvious, and as the PWM dimming has the characteristic of not changing the spectral wavelength, a good PWM dimming LED constant-current driving chip is more easily accepted by the market!
Fig. 1 shows a general LED linear constant current driving module. The module detects the voltage on the RCS resistor through a CS pin, inputs the voltage into an EA module (an error amplifier) of a chip, compares the voltage with a reference voltage and amplifies the voltage, outputs a constant DRV voltage and further enables an output LED lamp to be constant in current; PWM square wave signals are input through the PWM pins, and then the brightness of the LED lamp is modulated and output, so that the expected effect is achieved.
According to the traditional LED linear constant current module, a PWM square wave signal is used for dimming, the PWM signal is introduced into the EA amplifier module, and the EA amplifier module is switched on or off to achieve the PWM dimming effect.
Therefore, when the module enters PWM dimming, a certain time is required since the EA amplifier module is stable from off to on, which is called setup time; due to the existence of the establishment time, when the frequency of the PWM signal is higher or the duty ratio is lower, the linearity of the output current along with the linearity of the duty ratio is not kept linear and consistent any more.
The technical characteristics and the disadvantages of the traditional technology are that: when the traditional LED linear constant current module is used for PWM dimming, a certain setup time is needed from turning off to turning on of the EA amplifier module, and the setup time can affect the linearity of output current, and is particularly obvious when the PWM frequency is high or the duty ratio is small.
Disclosure of Invention
The invention aims to provide an LED constant current driving module which can adjust the frequency of a PWM dimming signal to be high under the condition that the periphery of a chip is not changed, so that the constant current linearity is expected, can be compatible with a PWM signal scheme with higher frequency, is more convenient for other systems to apply, and further enables the system to be stable during PWM dimming and outputs the LED constant current driving module which achieves the aim of the expected constant current linearity by designing an internal sampling and compensating module. Another objective of the present invention is to provide an LED constant current driving module in which the DRV driving signal of the chip and the input PWM signal are switched in the same phase, that is, when the frequency of the input PWM signal is high, the desired constant current linearity can be still maintained. It is still another object of the present invention to provide a method for increasing the input PWM dimming frequency of an LED linear constant current control system, so that the desired constant current linearity can be maintained when the input PWM signal frequency is high, and a stable voltage VC1 value of a loop compensation capacitor C1 can be obtained. And the whole chip system enters the LED constant current driving module in a stable constant current PWM control state.
The technical scheme of the invention is that the LED constant current driving module is characterized by comprising an error amplifier, a first switch, a second switch and a signal stabilizing module;
a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming current sampling resistor;
a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier;
the signal stabilizing module is connected with a signal output end of the error amplifier, when a dimming signal input end of the error amplifier is at a high level, the error amplifier controls the first switch to be switched on and controls the second switch to be switched off, and the signal stabilizing module outputs a first constant signal.
Preferably, the method comprises the following steps: the signal stabilizing module comprises a first capacitor and a second capacitor, wherein the first capacitor is connected with the second capacitor in parallel and is connected with the signal output end of the error amplifier.
Preferably, the method comprises the following steps: the dimming circuit is characterized by further comprising a buffer and a level shifter, the input end of the buffer is connected with the dimming signal input end, the output end of the buffer is connected with the input end of the level shifter, the level shifter is connected with the second capacitor in parallel, the level shifter shifts a dimming signal input by the dimming signal input end to the second capacitor, and the output end of the level shifter controls load work through the dimming signal after the level shifter is shifted.
Preferably, the method comprises the following steps: the first constant signal has the same value as the reference signal input from the reference signal input terminal.
The other technical scheme of the invention is that the LED constant current driving module is characterized by comprising an error amplifier, a first switch, a second switch and a signal stabilizing module;
a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming current sampling resistor;
a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier;
the signal stabilizing module is connected with a signal output end of the error amplifier, when a dimming signal input end of the error amplifier is at a low level, the error amplifier controls the first switch to be switched off and controls the second switch to be switched on, and a signal output end of the error amplifier outputs a second constant signal.
Preferably, the method comprises the following steps: still include buffer and level shifter, the input of buffer is connected adjust luminance signal input end, the output of buffer is connected level shifter's input error amplifier is in when error amplifier's the signal input of adjusting luminance is the low level, level shifter's output low level signal.
Preferably, the method comprises the following steps: and after the dimming signal input end of the error amplifier is changed from the low level to the high level, the error amplifier controls the first switch to be switched on and controls the second switch to be switched off, and the signal stabilizing module outputs a first constant signal.
Preferably, the method comprises the following steps: the signal stabilizing module comprises a first capacitor and a second capacitor, wherein the first capacitor is connected with the second capacitor in parallel and is connected with the signal output end of the error amplifier.
Preferably, the method comprises the following steps: the level shifter is connected with the second capacitor in parallel, the level shifter shifts the dimming signal input by the dimming signal input end to the second capacitor, and the output end of the level shifter controls the load to work through outputting the shifted dimming signal.
Preferably, the method comprises the following steps: the first constant signal has the same value as the reference signal input from the reference signal input terminal.
Compared with the prior art, the invention has the beneficial effects that:
the LED linear constant current driving module enables a system to adjust the frequency of a high PWM dimming signal without changing the periphery of a chip, so that the expected constant current linearity is achieved.
The DRV driving signal of the chip is switched with the input PWM signal in phase, so that expected constant current linearity can be kept when the frequency of the input PWM signal is high.
According to the invention, the input PWM dimming frequency of the LED linear constant-current control system can be obviously improved, so that the expected constant-current linearity can be still maintained when the input PWM signal frequency is higher.
The cycle of the invention is repeated, so that a stable voltage VC1 value of the loop compensation capacitor C1 can be obtained. And at this point, the whole chip system enters a stable constant current PWM control state.
Drawings
Fig. 1 is a circuit block diagram of a conventional LED constant current driving module;
fig. 2 is a circuit block diagram of an LED constant current driving module according to a first embodiment of the invention;
FIG. 3 is a waveform diagram of a key node of the LED linear constant current driving module according to the present invention;
fig. 4 is a circuit block diagram of an LED constant current driving module according to a second embodiment of the present invention.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings:
fig. 2 and 3 show a first embodiment of the present invention.
Referring to fig. 2 and 3, the LED constant current driving module includes an error amplifier, a first switch, a second switch, a first capacitor, a second capacitor, a buffer and a level shifter; the first capacitor is connected with the second capacitor in parallel and is connected with the signal output end of the error amplifier; a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming current sampling resistor; a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier;
the signal output end of the error amplifier is respectively connected with a grid electrode of a second MOS tube and one end of a first capacitor, a source electrode of the second MOS tube is respectively connected with the second capacitor and a level shifter, the output end of the level shifter is connected with the grid electrode of the first MOS tube, the source electrode of the first MOS tube is connected with a common end of a dimming current sampling resistor and a CS pin, and a drain electrode of the first MOS tube is connected with a load LED; when the dimming signal input end of the error amplifier is at a high level, the constant current driving module controls the first switch to be switched on and controls the second switch to be switched off, and the first capacitor and the second capacitor output a first constant signal; the value of the first constant signal is the same as that of the reference signal input by the reference signal input end;
the input end of the buffer is connected with the dimming signal input end, the output end of the buffer is connected with the input end of the level shifter, the level shifter is connected with the second capacitor in parallel, the level shifter shifts the dimming signal input by the dimming signal input end to the second capacitor, and the output end of the level shifter controls the load to work through the dimming signal after the output displacement.
And an error amplifier, the other end of a second capacitor with a drain electrode of a second MSO tube connected with a source electrode of the second MSO tube, a buffer, a load and the other end of the dimming current sampling resistor are sequentially connected in parallel between the working voltage VDD of the power supply inside the LED constant current driving module and the voltage of the common ground VSS of the circuit.
The working principle of the LED constant current driving module is as follows: an error amplifier of the chip sends the detected voltage of the CS pin to the error amplifier, so that the voltage on the first capacitor is gradually increased, then the voltage on a second capacitor output by a source follower controlled by the output voltage of the error amplifier is gradually increased, and after the voltage on the CS pin is stabilized, the voltage of the CS pin is just equal to a reference voltage REF; at the moment, the PWM input signal is also input to the input end of the level shifter through the buffer, and because the PWM signal is H at the moment, the level shifter shifts the VDD voltage when the PWM signal is input to H to output the voltage on the second capacitor, and then the voltage is output to a DRV pin through the level shifter, and the peripheral first MOS tube is controlled to be gradually conducted; then from the power supply VDD, through the load LED, through the first MOS transistor, through the dimming current sampling resistor RCSA current loop is formed for the ground; when the voltage of the pin CS is just equal to the reference voltage REF, the chip tends to be stable; when the PWM signal is L, the first switch is controlled to be switched off, the second switch is controlled to be switched on, and at the moment, the input of the error amplifier is in short circuit connection, so that the output of the error amplifier is unchanged; at this time, the PWM signal is L, and is input to the power supply after passing through the bufferThe level shifter outputs L in the same way, namely the DRV signal output is pulled to the ground, and at the moment, the first peripheral MOS tube is switched off and has no output current; when the PWM signal is H again, the voltage on the output second capacitor is output to the DRV pin through the level shifter, so that the CS voltage which can quickly tend to be stable is output; the above steps are repeated in a circulating way, so that a stable voltage value of the loop compensation first capacitor can be obtained, and the whole chip system enters a stable constant current PWM control state.
Fig. 4 shows a second embodiment of the invention.
Referring to fig. 4, the LED constant current driving module includes an error amplifier, a first switch and a second switch; a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming current sampling resistor; a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier; the signal stabilizing module is connected with a signal output end of the error amplifier, when a dimming signal input end of the error amplifier is at a low level, the error amplifier controls the first switch to be switched off and controls the second switch to be switched on, and a signal output end of the error amplifier outputs a second constant signal.
The LED constant current driving module further comprises a buffer and a level shifter, the input end of the buffer is connected with the dimming signal input end, the output end of the buffer is connected with the input end of the level shifter, and when the dimming signal input end of the error amplifier is at a low level, the output end of the level shifter outputs a low level signal.
The error amplifier controls the first switch to be switched on and controls the second switch to be switched off after the dimming signal input end of the error amplifier is changed from the low level to the high level, the signal stabilizing module outputs a first constant signal, and the value of the first constant signal is the same as that of the reference signal input end.
The LED constant current driving module further comprises a signal stabilizing module, the signal stabilizing module comprises a first capacitor and a second capacitor, and the first capacitor is connected with the second capacitor in parallel and is connected with the signal output end of the error amplifier. The level shifter is connected with the second capacitor in parallel, the level shifter shifts the dimming signal input by the dimming signal input end to the second capacitor, and the output end of the level shifter controls the load to work through outputting the shifted dimming signal.
The LED constant current driving module further comprises a first MSO tube and a second MSO tube, the grid electrode of the first MSO tube is connected with the output end of the level shifter, the source electrode of the first MSO tube is connected with the dimming current sampling resistor and the common end of the CS pin, and the drain electrode of the first MOS tube is connected with the load LED; the grid electrode of the second MOS tube is respectively connected with the signal output end of the error amplifier and one end of the first capacitor, the source electrode of the second MOS tube is respectively connected with the second capacitor and the level shifter,
and a diode, an error amplifier, the other end of a second capacitor with a drain electrode of a second MSO tube connected with a source electrode of the second MSO tube and a buffer are sequentially connected in parallel between the working voltage VDD of the power supply inside the LED constant current driving module and the voltage of the common ground VSS of the circuit. The common ground VSS end pin of the circuit is connected with one end of a capacitor, the other end of the capacitor is respectively connected with the working voltage VDD and one end of a peripheral resistor, and the other end of the peripheral resistor is connected with an input voltage VIN and a common end of a load multi-string LED.
The working principle of the LED constant current driving module is as follows: the LED constant current driving module is characterized in that the input voltage VIN is higher input voltage, and VDD voltage is obtained through a peripheral resistor and a capacitor to supply power to the chip. The other chip operation principle is consistent with the foregoing embodiment, that is, when stable, a stable voltage for compensating the first capacitor and a stable voltage for filtering the second capacitor can be obtained, so that the output DRV driving signal of the level shifter is stable. Also, when stable, a higher PWM signal frequency can be input and a desired constant linearity can be obtained. Other related technical details are the same as those of the previous embodiment, and are not described herein again.
The above-mentioned embodiments are only preferred embodiments of the present invention, and all equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.
Claims (10)
1. An LED constant current driving module is characterized by comprising an error amplifier, a first switch, a second switch and a signal stabilizing module;
a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming current sampling resistor;
a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier;
the signal stabilizing module is connected with a signal output end of the error amplifier, when a dimming signal input end of the error amplifier is at a high level, the error amplifier controls the first switch to be switched on and controls the second switch to be switched off, and the signal stabilizing module outputs a first constant signal.
2. The LED constant current driving module according to claim 1, wherein the signal stabilizing module comprises a first capacitor and a second capacitor, and the first capacitor is connected in parallel with the second capacitor and is connected with a signal output end of the error amplifier.
3. The LED constant current driving module according to claim 2, further comprising a buffer and a level shifter, wherein an input end of the buffer is connected to the dimming signal input end, an output end of the buffer is connected to an input end of the level shifter, the level shifter is connected in parallel to the second capacitor, the level shifter shifts the dimming signal input from the dimming signal input end to the second capacitor, and an output end of the level shifter controls a load to operate by outputting the shifted dimming signal.
4. The LED constant current driving module according to claim 3, wherein the first constant signal has the same value as a reference signal input from the reference signal input terminal.
5. An LED constant current driving module is characterized by comprising an error amplifier, a first switch, a second switch and a signal stabilizing module;
a first end of the first switch is connected with a signal detection input end of the error amplifier, a second end of the first switch is connected with a signal detection end of the error amplifier, and the signal detection end of the error amplifier is used for detecting an output signal of the dimming current sampling resistor;
a first end of the second switch is connected with a reference signal input end of the error amplifier, and a second end of the second switch is connected with the signal detection input end of the error amplifier;
the signal stabilizing module is connected with a signal output end of the error amplifier, when a dimming signal input end of the error amplifier is at a low level, the error amplifier controls the first switch to be switched off and controls the second switch to be switched on, and a signal output end of the error amplifier outputs a second constant signal.
6. The LED constant current driving module according to claim 5, further comprising a buffer and a level shifter, wherein an input terminal of the buffer is connected to the dimming signal input terminal, an output terminal of the buffer is connected to an input terminal of the level shifter, and when the dimming signal input terminal of the error amplifier is at a low level, an output terminal of the level shifter outputs a low level signal.
7. The LED constant current driving module according to claim 6, wherein the error amplifier controls the first switch to be turned on and controls the second switch to be turned off after a dimming signal input terminal of the error amplifier changes from the low level to the high level, and the signal stabilizing module outputs a first constant signal.
8. The LED constant current driving module according to claim 7, wherein the signal stabilizing module comprises a first capacitor and a second capacitor, and the first capacitor is connected in parallel with the second capacitor and is connected with a signal output end of the error amplifier.
9. The LED constant current driving module according to claim 8, wherein the level shifter is connected in parallel with the second capacitor, the level shifter shifts the dimming signal input from the dimming signal input terminal to the second capacitor, and the output terminal of the level shifter controls a load to operate by outputting the shifted dimming signal.
10. The LED constant current driving module according to claim 9, wherein the first constant signal has the same value as a reference signal input from the reference signal input terminal.
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| CN201811234174.9A CN109302771B (en) | 2018-10-23 | 2018-10-23 | LED constant current driving module |
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| CN201811234174.9A CN109302771B (en) | 2018-10-23 | 2018-10-23 | LED constant current driving module |
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| CN110493925B (en) * | 2019-08-30 | 2022-06-17 | 杭州茂力半导体技术有限公司 | Light emitting element driving device, controller thereof and dimming method |
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| CN101754513A (en) * | 2008-12-03 | 2010-06-23 | 德信科技股份有限公司 | Controllable soft starting and soft shut-off circuit with pulse width modulation function |
| CN206640841U (en) * | 2017-04-10 | 2017-11-14 | 深圳天源中芯半导体有限公司 | A kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power |
| CN107482795A (en) * | 2017-09-15 | 2017-12-15 | 苏州加士革电子科技有限公司 | A kind of 6.78Mhz resonance wireless charging receiving circuit |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101754513A (en) * | 2008-12-03 | 2010-06-23 | 德信科技股份有限公司 | Controllable soft starting and soft shut-off circuit with pulse width modulation function |
| CN206640841U (en) * | 2017-04-10 | 2017-11-14 | 深圳天源中芯半导体有限公司 | A kind of PWM light adjusting circuits for High Power Factor primary side feedback LED drive power |
| CN107482795A (en) * | 2017-09-15 | 2017-12-15 | 苏州加士革电子科技有限公司 | A kind of 6.78Mhz resonance wireless charging receiving circuit |
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