CN202713720U - PWM dimming signal generating circuit - Google Patents
PWM dimming signal generating circuit Download PDFInfo
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- CN202713720U CN202713720U CN 201220329313 CN201220329313U CN202713720U CN 202713720 U CN202713720 U CN 202713720U CN 201220329313 CN201220329313 CN 201220329313 CN 201220329313 U CN201220329313 U CN 201220329313U CN 202713720 U CN202713720 U CN 202713720U
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Abstract
The utility model discloses a PWM dimming signal generating circuit, which comprises a self-excitation unit used for generating a first waveform, a control signal conversion unit used for controlling input signals to generate a second waveform, and a signal comparison unit used for generating PWM dimming signals according to the first waveform and the second waveform; wherein the self-excitation unit and the control signal conversion unit are separately connected with the signal comparison unit. After a circuit is started, the first waveform generated by the self-excitation unit and the second waveform generated by the control signal conversion unit are respectively input to a same-phase input end and a reverse-phase input end of an operational amplifier in the control signal comparison unit, and the PWM dimming signals are output after operation and comparison carried out by a second operational amplifier. According to the utility model, the PWM dimming signals can be generated just by using the two low-cost operational amplifiers and the circuit can be compatible with a resistance dimmer so that the cost is saved and dimming systems can be flexibly selected according to different light requirements.
Description
Technical field
The utility model relates to LED light regulating technology field, particularly a kind of PWM dim signal circuit for generating.
Background technology
PWM(Pulse Width Modulation, pulse width modulation) light modulation is a kind of simple digit pulse that utilizes, the repeatedly light regulating technology of switch led driver.Application person's system only need to provide wide, narrow different digital type pulse, can realize simply changing output current, thereby regulates the brightness of white light LEDs.The PWM light modulation can provide high-quality white light, uses simply, and efficient is high, and can not make LED produce colour cast, is widely used in the LED dimming driver.
The dim signal that uses at present is the analog signal of 1 ~ 10V, needs a circuit to realize that analog signal arrives the conversion of PWM dim signal.This circuit produces triangular wave or sawtooth waveforms by two operational amplifier self-excitations usually, thereby then by the 3rd operational amplifier the analog signal of triangular wave or sawtooth waveforms and input is relatively produced pwm signal.See also Fig. 1, it is PWM dim signal circuit for generating of the prior art, and as shown in the figure, setting power input voltage is V
CC, when circuit was started working, the output initial voltage of the first operational amplifier IC1A was V
CC, make triode Q1 conducting, connect with the 3rd resistance R 3 again after the 4th resistance R 4 and 5 parallel connections of the 5th resistance R, at this moment, the inverting input magnitude of voltage of the first operational amplifier IC1A is
, wherein
The first capacitor C 1, the six resistance R 6 and the second operational amplifier IC1B form integrating circuit.When initial, the output end voltage of the first operational amplifier IC1A
, the in-phase input end voltage of the second operational amplifier IC1B is
, the output initial voltage of the second operational amplifier IC1B is
So the output end voltage expression formula of the second operational amplifier IC1B is
Can find out that the output initial voltage of the second operational amplifier IC1B is
, and along with linear decline of time.When voltage drop arrives
The time, the output of the first operational amplifier IC1A oppositely is output as 0V, both
, triode Q1 turn-offs, and the anti-phase input terminal voltage of the first operational amplifier IC1A is
At this moment, the in-phase input end voltage of the second operational amplifier IC1B remains
, the output initial voltage of the second operational amplifier IC1B is
So the output end voltage expression formula of the second operational amplifier IC1B is
Can find out that the output initial voltage of the second operational amplifier IC1B is
, and along with linear rising of time.When voltage rises to
The time, the output of the first operational amplifier IC1A oppositely is output as V
CC, namely
, triode Q1 conducting, afterwards again take the output initial voltage of the second operational amplifier IC1B as
Repeat next cycle.So circulation, along with triode Q1 turn-on and turn-off, the output end voltage of the second operational amplifier IC1B repeatedly from
Drop to
, then again from
Rise to
So maximum voltage value of output output of the second operational amplifier IC1B is
, minimum voltage is
Triangular signal, its frequency is determined by the first capacitor C 1 and the 6th resistance R 6.
The direct current dim signal is by the end input of the 7th resistance R 7, in-phase input end by input the 3rd operational amplifier IC1C after the 7th resistance R 7 and the 8th resistance R 8 dividing potential drops, and compare by the 3rd operational amplifier IC1C with triangular signal, thereby produce corresponding pwm signal at the output of the 3rd operational amplifier IC1C.
Wherein, triode Q1 is N channel enhancement metal-oxide-semiconductor, and the positive power source terminal of the first operational amplifier IC1A, the second operational amplifier IC1B and the 3rd operational amplifier IC1C and negative power end connect respectively power input V
CCAnd ground.
Foregoing circuit needs three amplifiers could produce the PWM dim signal, just needs to adopt in actual applications the four high guaily unit chip of similar LM324, has namely increased cost, has increased again the area of pcb board.Simultaneously, the direct current dim signal in the foregoing circuit is direct voltage, can not compatible resistance dimmer, because the resistance dimmer is a kind of passive dimmer, with respect to direct current signal, it is with low cost, and is easy for installation.Therefore, if can not compatible resistance dimmer, not only can not select more neatly light adjusting system.Also can increase cost, trouble is installed.
Thereby prior art is still waiting to improve and improve.
The utility model content
In view of above-mentioned the deficiencies in the prior art part, the purpose of this utility model is to provide a kind of PWM dim signal circuit for generating, and compatible resistance dimmer reaches better dimming effect when being intended to Cost reduction.
In order to achieve the above object, the utility model has been taked following technical scheme:
A kind of PWM dim signal circuit for generating, it comprises:
Self-excitation unit for generation of the first waveform;
Be used for the control signal converting unit that the control inputs signal produces the second waveform;
Be used for according to the first waveform and the second waveform, produce the signal comparing unit of PWM dim signal;
Described self-excitation unit and control signal converting unit connect respectively the signal comparing unit.
Described PWM dim signal circuit for generating, wherein, described self-excitation unit comprises: the first operational amplifier, the first diode, the first electric capacity, the first resistance, the second resistance, the 3rd resistance and the 4th resistance; One end of described the first resistance is by the first capacity earth, another termination power input, the inverting input of described the first operational amplifier connects an end and the signal comparing unit of described the first resistance, this inverting input also connects the positive pole of the first diode by the second resistance, the in-phase input end of the first operational amplifier connects reference voltage by the 3rd resistance, this in-phase input end also connects respectively the negative pole of the first diode and the output of the first operational amplifier by the 4th resistance, and the positive power source terminal of the first operational amplifier and negative power end connect respectively power input and ground.
Described PWM dim signal circuit for generating, wherein, described control signal converting unit comprises: the second diode, the second electric capacity, voltage stabilizing didoe, the 6th resistance, the 7th resistance and the 8th resistance; The positive pole of described the second diode connects power input, negative pole connects respectively an end of signal input part, the 7th resistance and the negative pole of voltage stabilizing didoe by the 8th resistance, the plus earth of described voltage stabilizing didoe, the other end of described the 7th resistance connects the signal comparing unit, also by the 6th grounding through resistance, the second electric capacity is in parallel with the 6th resistance for this other end.
Described PWM dim signal circuit for generating, wherein, described signal comparing unit comprises: the second operational amplifier and the 5th resistance; The inverting input of described the second operational amplifier connects the self-excitation unit, its in-phase input end connection control signal converting unit, and its output connects signal output part, its positive supply termination power input, its negative power end ground connection by the 5th resistance.
Described PWM dim signal circuit for generating, wherein, described the first waveform is triangular wave or sawtooth waveforms.
Compared to prior art, the PWM dim signal circuit for generating that the utility model provides, produce the first waveform by the self-excitation unit, the control signal converting unit is controlled the dim signal of input and is produced the second waveform, the first waveform and the second waveform input signal comparing unit are compared, thereby produce corresponding PWM dim signal.The utility model PWM dim signal circuit for generating only needs two operational amplifiers just can generate the PWM dim signal, can select such as LM358 during practical application, the low-cost dual operational amplifier chip such as LM2904, when reducing production costs, the control signal converting unit can compatible 1 ~ 10V direct voltage and resistance dimmer, can select neatly light adjusting system according to different requirement of light regulation.
Description of drawings
Fig. 1 is the PWM dim signal circuit for generating of prior art.
Fig. 2 is the structured flowchart of the utility model PWM dim signal circuit for generating.
Fig. 3 is the circuit diagram of the embodiment of the utility model PWM dim signal circuit for generating.
Fig. 4 is the oscillogram of the first waveform among the embodiment of the utility model PWM dim signal circuit for generating.
Fig. 5 is the oscillogram of PWM dim signal among the embodiment of the utility model PWM dim signal circuit for generating.
Embodiment
The utility model provides a kind of PWM dim signal circuit for generating, and is clearer, clear and definite for making the purpose of this utility model, technical scheme and effect, referring to the accompanying drawing embodiment that develops simultaneously the utility model further described.Should be appreciated that specific embodiment described herein only in order to explaining the utility model, and be not used in restriction the utility model.
See also Fig. 2, it is the structured flowchart of the utility model PWM dim signal circuit for generating, and as shown in the figure, it comprises self-excitation unit 100, control signal converting unit 200 and signal comparing unit 300; Are connected with the control signal converting unit and connect respectively signal comparing unit 300 in described self-excitation unit 100.Self-excitation unit 100 is for generation of the first waveform, and control signal converting unit 200 is used for the control inputs signal and produces the second waveform and compatible resistance dimmer, and the signal comparing unit is used for according to above-mentioned the first waveform and the second waveform generation PWM dim signal.
In the present embodiment, described the first waveform is triangular wave or sawtooth waveforms, and the second waveform is DC level, and the PWM dim signal is square wave, and its duty ratio can be determined that by the magnitude of voltage of direct voltage perhaps the resistance of resistance dimmer determines.
Please consult simultaneously Fig. 3, it is the circuit diagram of the embodiment of the utility model PWM dim signal circuit for generating, as shown in the figure, described self-excitation unit 100 comprises: the first operational amplifier IC2A, the first diode D1, the first capacitor C 1, the first resistance R 1, the second resistance R 2, the 3rd resistance R 3 and the 4th resistance R 4; Described control signal converting unit 200 comprises: the second diode D2, the second capacitor C 2, voltage stabilizing didoe D3, the 6th resistance R 6, the 7th resistance R 7 and the 8th resistance R 8; Described signal comparing unit 300 comprises: the second operational amplifier IC2B and the 5th resistance R 5.
One end of described the first resistance R 1 is by the first capacitor C 1 ground connection, another termination power input V
CC, V
CCDescribed power input is used for input power, the inverting input of described the first operational amplifier IC2A connects an end of described the first resistance R 1 and the inverting input of the second operational amplifier IC2B, the inverting input of the first operational amplifier IC2A also connects the positive pole of the first diode D1 by the second resistance R 2, the in-phase input end of the first operational amplifier IC2A connects the reference voltage input terminal HL that is used for input reference voltage by the 3rd resistance R 3, and this in-phase input end also connects respectively the negative pole of the first diode D1 and the output of the first operational amplifier IC2A by the 4th resistance R 4.
The positive pole of described the second diode D2 meets power input V
CCNegative pole connects respectively an end of signal input part Vin, the 7th resistance R 7 and the negative pole of voltage stabilizing didoe D3 by the 8th resistance R 8, the plus earth of described voltage stabilizing didoe D3, the other end of described the 7th resistance R 7 connects the in-phase input end of the second operational amplifier IC2B, also by the 6th resistance R 6 ground connection, the second capacitor C 2 is in parallel with the 6th resistance R 6 for the other end of the 7th resistance R 7.
The output of described the second operational amplifier IC2B connects signal output part Vout by the 5th resistance R 5.
The first operational amplifier IC2A be connected positive power source terminal and the negative power end of operational amplifier IC2B and connect respectively power input V
CCAnd ground.
In the utility model embodiment, 5 metering functions of the 5th resistance R; Signal input part Vin can input direct voltage or the resistance dimmer (not shown in FIG.) of 1 ~ 10V, if input is the direct voltage of 1 ~ 10V, then the second waveform is that its size is by the DC level after the 6th resistance R 6 and the 7th resistance R 7 dividing potential drops
, Vin represents that voltage range is 1 ~ 10V.If signal input part Vin has connected the resistance dimmer, then the second waveform is to have reflected that the second diode D2, the 8th resistance R 8 and dimmer resistance are converted into this process of change in voltage to the variation of dimmer resistance, also export a direct current level.The resistance dimmer can equivalence be a variable resistor, is connected between signal input part Vin and the ground, connect dimming interface after, change into a d. c. voltage signal; The signal of signal output part Vout output namely is the PWM dim signal; Described voltage stabilizing didoe D3 is the 10V voltage stabilizing didoe, and when not accessing dim signal, the signal equivalence of input Vin input is the 10V direct voltage.Described the first operational amplifier IC2A and the second operational amplifier IC2B can adopt the dual operational amplifier chips such as LM358, LM2904.In the present embodiment, the voltage range of described reference voltage HL is greater than 0.7V, less than 12V.
In the specific implementation, please continue to consult Fig. 3, set power input V
CCInput voltage be 12V, the voltage of reference voltage HL is 2.5V, the input signal of signal input part Vin is 1 ~ 10V direct voltage, and the first operational amplifier IC2A and the second operational amplifier IC2B are ideal operational amplifier, and the anti-phase input terminal voltage of the first operational amplifier IC2A is
, in-phase input end voltage is
Operational amplifier adopts single power supply, access power input V
CCAfter, circuit start, according to the operation principle of operational amplifier as can be known, the beginning is during state,
Voltage be 0V,
Voltage greater than
Voltage, therefore the output initial voltage of the first operational amplifier IC2A is 12V, at this moment, the magnitude of voltage on the in-phase input end of the first operational amplifier IC2A is the voltage ratio of the 3rd resistance R 3 and the 4th resistance R 4, can be got by proportionate relationship:
, can derive:
Power input V
CCTo 1 charging of the first capacitor C, the voltage of the first capacitor C 1 raises gradually, when magnitude of voltage rises to above V by the first resistance R 1
PIN3Value, i.e. V
PIN2Voltage greater than V
PIN3Voltage, then the output end voltage value of the first operational amplifier IC2A oppositely is output as 0V, uses
The in-phase input end magnitude of voltage that represents the first operational amplifier IC2A this moment.Can be got by proportionate relationship:
, can derive:
The first capacitor C 1 is by 2 discharges of the second resistance R, and the voltage on the first capacitor C 1 reduces gradually, is lower than when magnitude of voltage drops to
Value, the output end voltage value of the first operational amplifier IC2A oppositely is output as 12V again, the first diode D1 cut-off this moment, power input V
CCVoltage 12V continue by the first resistance R 1 to 1 charging of the first capacitor C, repeat above-mentioned steps, finally the inverting input at the first operational amplifier IC2A can produce the first waveform, be a sawtooth signal, as shown in Figure 4, the frequency size of this sawtooth signal is determined by the size of the first resistance R 1 and the first capacitor C 1.The ceiling voltage of this sawtooth signal equals
, this moment, the output end voltage value of the first operational amplifier IC2A was 12V; The minimum voltage of this sawtooth signal equals
, this moment, the output end voltage value of the first operational amplifier IC2A was 0V.
The input signal of signal input part Vin is 1 ~ 10V direct voltage, and this direct voltage produces the second waveform after through the 7th resistance R 7 and the 6th resistance R 6 dividing potential drops, is a direct current level, the magnitude of voltage of this level
Sawtooth waveforms is inputted the inverting input of the second operational amplifier IC2B, and DC level is inputted the in-phase input end of the second operational amplifier IC2B, when the voltage of sawtooth waveforms during less than the voltage of DC level, and the output output voltage 12V of the second operational amplifier IC2B; When the voltage of sawtooth waveforms during greater than the voltage of DC level, the output output voltage 0V of the second operational amplifier IC2B; Finally producing corresponding PWM dim signal at signal output part Vout, is a square wave, as shown in Figure 5.The duty ratio of this square wave is determined by the magnitude of voltage of DC level, also can be determined by the equivalent voltage value behind the access resistance dimmer.。
In sum, the PWM dim signal circuit for generating that the utility model provides, comprise the self-excitation unit, control signal converting unit and signal comparing unit, behind the access power input voltage starting circuit, compare by the anti-phase input terminal voltage of the first operational amplifier and the size of in-phase input end voltage, change the situation that charges and discharge of the first electric capacity, thereby produce the first waveform and transfer to the inverting input of the second operational amplifier at the inverting input of the first operational amplifier, the voltage of signal input part input is through producing the second waveform and transfer to the in-phase input end of the second operational amplifier after the dividing potential drop, through after the second operational amplifier computing relatively at its output output PWM dim signal.The utility model only adopt two cheaply operational amplifier just can produce the PWM dim signal, compatible resistance dimmer has also namely been saved cost simultaneously, can select neatly light adjusting system according to different requirement of light regulation again.。
Be understandable that; for those of ordinary skills; can be equal to replacement or change according to the technical solution of the utility model and utility model design thereof, and all these changes or replacement all should belong to the protection range of the appended claim of the utility model.
Claims (5)
1. a PWM dim signal circuit for generating is characterized in that, comprising:
Self-excitation unit for generation of the first waveform;
Be used for the control signal converting unit that the control inputs signal produces the second waveform;
Be used for according to the first waveform and the second waveform, produce the signal comparing unit of PWM dim signal;
Described self-excitation unit and control signal converting unit connect respectively the signal comparing unit.
2. PWM dim signal circuit for generating according to claim 1 is characterized in that, described self-excitation unit comprises: the first operational amplifier, the first diode, the first electric capacity, the first resistance, the second resistance, the 3rd resistance and the 4th resistance; One end of described the first resistance is by the first capacity earth, another termination power input, the inverting input of described the first operational amplifier connects an end and the signal comparing unit of described the first resistance, this inverting input also connects the positive pole of the first diode by the second resistance, the in-phase input end of the first operational amplifier connects reference voltage by the 3rd resistance, this in-phase input end also connects respectively the negative pole of the first diode and the output of the first operational amplifier by the 4th resistance, and the positive power source terminal of the first operational amplifier and negative power end connect respectively power input and ground.
3. PWM dim signal circuit for generating according to claim 1 is characterized in that, described control signal converting unit comprises: the second diode, the second electric capacity, voltage stabilizing didoe, the 6th resistance, the 7th resistance and the 8th resistance; The positive pole of described the second diode connects power input, negative pole connects respectively an end of signal input part, the 7th resistance and the negative pole of voltage stabilizing didoe by the 8th resistance, the plus earth of described voltage stabilizing didoe, the other end of described the 7th resistance connects the signal comparing unit, also by the 6th grounding through resistance, the second electric capacity is in parallel with the 6th resistance for this other end.
4. according to claim 1 to 3 arbitrary described PWM dim signal circuit for generatings, it is characterized in that described signal comparing unit comprises: the second operational amplifier and the 5th resistance; The inverting input of described the second operational amplifier connects the self-excitation unit, its in-phase input end connection control signal converting unit, and its output connects signal output part, its positive supply termination power input, its negative power end ground connection by the 5th resistance.
5. PWM dim signal circuit for generating according to claim 1 is characterized in that, described the first waveform is triangular wave or sawtooth waveforms.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220329313 CN202713720U (en) | 2012-07-09 | 2012-07-09 | PWM dimming signal generating circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220329313 CN202713720U (en) | 2012-07-09 | 2012-07-09 | PWM dimming signal generating circuit |
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| CN202713720U true CN202713720U (en) | 2013-01-30 |
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| CN 201220329313 Expired - Fee Related CN202713720U (en) | 2012-07-09 | 2012-07-09 | PWM dimming signal generating circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108494387A (en) * | 2018-03-26 | 2018-09-04 | 慈溪市中发灯饰有限公司 | It can operation type PWM generation circuits |
| CN108744277A (en) * | 2018-06-28 | 2018-11-06 | 杭州首时科技有限公司 | Neuromuscular stimulators |
| CN111030653A (en) * | 2019-12-24 | 2020-04-17 | 珠海凯邦电机制造有限公司 | PWM signal generating circuit and sawtooth wave signal generating circuit |
| CN113765464A (en) * | 2020-05-28 | 2021-12-07 | 广东美的暖通设备有限公司 | Voltage conversion device, motor control system and air conditioner |
| CN115734428A (en) * | 2022-12-28 | 2023-03-03 | 威海中远海运重工科技有限公司 | Constant-power stepless dimming control system |
-
2012
- 2012-07-09 CN CN 201220329313 patent/CN202713720U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108494387A (en) * | 2018-03-26 | 2018-09-04 | 慈溪市中发灯饰有限公司 | It can operation type PWM generation circuits |
| CN108494387B (en) * | 2018-03-26 | 2022-04-19 | 慈溪市中发灯饰有限公司 | Operational PWM generating circuit |
| CN108744277A (en) * | 2018-06-28 | 2018-11-06 | 杭州首时科技有限公司 | Neuromuscular stimulators |
| CN111030653A (en) * | 2019-12-24 | 2020-04-17 | 珠海凯邦电机制造有限公司 | PWM signal generating circuit and sawtooth wave signal generating circuit |
| CN113765464A (en) * | 2020-05-28 | 2021-12-07 | 广东美的暖通设备有限公司 | Voltage conversion device, motor control system and air conditioner |
| CN115734428A (en) * | 2022-12-28 | 2023-03-03 | 威海中远海运重工科技有限公司 | Constant-power stepless dimming control system |
| CN115734428B (en) * | 2022-12-28 | 2024-05-31 | 威海中远海运重工科技有限公司 | Constant-power electrodeless dimming control system |
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Granted publication date: 20130130 Termination date: 20200709 |
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