CN213783662U - Constant voltage output dimming circuit of lamp source - Google Patents
Constant voltage output dimming circuit of lamp source Download PDFInfo
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- CN213783662U CN213783662U CN202022715542.0U CN202022715542U CN213783662U CN 213783662 U CN213783662 U CN 213783662U CN 202022715542 U CN202022715542 U CN 202022715542U CN 213783662 U CN213783662 U CN 213783662U
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Abstract
The application relates to the technical field of lamp dimming, in particular to a lamp source constant voltage output dimming circuit. The dimming circuit comprises a constant voltage output circuit and a dimming control circuit; the dimming control circuit is arranged on the output side of the constant voltage output circuit and is used for realizing dimming of the lamp source; the dimming control circuit comprises a dimming MOS tube, a signal output circuit and a comparison control circuit; the source electrode and the drain electrode of the dimming MOS tube are respectively connected between the output end and the grounding end of the constant-voltage dimming circuit, and the grid electrode of the dimming MOS tube is connected with the signal output circuit; a detection resistor is arranged between the dimming MOS tube and the grounding end; the detection end of the comparison control circuit is connected to the drain electrode of the dimming MOS tube, the output end of the comparison control circuit is connected with the signal output circuit, the comparison control circuit monitors the collected voltage, and when the voltage exceeds the preset voltage, continuous turn-off of the output signal of the signal output circuit is achieved. The circuit is reliable and effective, does not need an isolation circuit, is suitable for an extensive lamp strip constant voltage output circuit, and reduces the cost in the aspect of short-circuit protection of the dimming circuit.
Description
Technical Field
The application relates to the technical field of lamp dimming, in particular to a lamp source constant voltage output dimming circuit.
Background
Along with the development of the lamp industry, the market demand for lamp strip dimming products is increasing day by day, and the lamp strip is traditionally driven to be constant voltage drive power supply, comprises singlechip control circuit and dimming MOS through the output, realizes the function of adjusting luminance. This method has low cost and good dimming effect, but has a natural defect that when the dimming MOS is connected between the load and the power supply output, so that a short circuit occurs, the preceding stage control circuit cannot quickly detect the abnormality of the secondary output, so that the preceding stage is not protected, and the dimming MOS of the subsequent stage cannot bear the energy supplied by the preceding stage, so that the MOS breakdown fails to realize the dimming function.
In the current market, the mainstream current monitoring short-circuit protection circuit realizes output short-circuit protection by acquiring current signals through the MCU, the scheme also has the problem of an application range, when the product is dimmed at 0-10V, the 3C certification of the product requires that the 0-10V signals and the output circuit are basically insulated, and at the moment, the acquisition of the short-circuit signals needs to be isolated and then the MCU can be used for signal analysis. The isolation circuit of the analog signal is very complex and high in cost, so that the circuit is not suitable for 0-10V safety products, and the applicability of the circuit is low.
Disclosure of Invention
The application provides a lamp source constant voltage output dimming circuit for solving the problems of complex structure, high cost and poor applicability of the current dimming circuit in the aspect of short circuit protection.
In order to solve the technical problem, the technical scheme of the application is as follows:
a lamp source constant voltage output dimming circuit comprises a constant voltage output circuit and a dimming control circuit; the dimming control circuit is arranged on the output side of the constant voltage output circuit and is used for realizing dimming of the lamp source; the dimming control circuit comprises a dimming MOS tube, a signal output circuit and a comparison control circuit; the source electrode and the drain electrode of the dimming MOS tube are respectively connected between the output end and the grounding end of the constant-voltage dimming circuit, and the grid electrode of the dimming MOS tube is connected with the signal output circuit; a detection resistor is arranged between the dimming MOS tube and the grounding end; the detection end of the comparison control circuit is connected to the drain electrode of the dimming MOS tube to collect the output voltage of the drain electrode of the dimming MOS tube, the output end of the comparison control circuit is connected with the signal output circuit, the comparison control circuit monitors the collected voltage, and when the voltage exceeds the preset voltage, the signal output circuit can continuously turn off the output signal of the dimming MOS tube.
Further, the comparison control circuit comprises a comparison circuit and a switch circuit; the detection end of the comparison circuit is connected with the drain electrode of the dimming MOS tube, the reference end of the comparison circuit is connected with an external reference voltage output end, and the output end of the comparison circuit is connected with the control end of the switch circuit; the input end and the output end of the switch circuit are respectively connected with the output end of the signal output circuit and the ground wire, and the conduction between the signal output circuit and the ground wire is controlled according to the input of the comparison circuit, so that the signal output circuit is turned off when outputting signals to the dimming MOS tube.
Furthermore, a self-locking module is arranged between the output end and the detection end of the comparison circuit; when the output end of the comparison circuit outputs a high level, the continuous output of the high level is realized through the self-locking module.
Further, the self-locking module comprises a diode, and an input end and an output end of the diode are respectively connected with an output end and a detection end of the comparison circuit.
Furthermore, the comparison circuit comprises a comparator, the detection end of the comparator is connected with the drain electrode of the dimming MOS tube, the reference end of the comparator is connected with the external reference voltage output end, the power supply end of the comparator is connected with the external input power supply, and the output end of the comparator is connected with the control end of the switch circuit.
Furthermore, the comparison circuit further comprises a filter resistor arranged on the detection end.
Further, the switch circuit comprises a first triode; and the base electrode of the first triode is connected with the output end of the comparison circuit, and the collector electrode and the emitter electrode are respectively connected with the output end of the signal output circuit and the ground wire.
Further, the first triode is an NPN-type triode.
Further, the device also comprises a first voltage regulating resistor and a second voltage regulating resistor; the first voltage regulating resistor is arranged between the base electrode of the first triode and the output end of the comparison circuit; the second voltage regulating resistor is connected between the base electrode of the first triode and the ground wire in series.
Further, the signal output circuit is used for outputting a PWM dimming signal to the dimming MOS transistor.
This application is through setting up detection resistance at the MOS pipe output end of adjusting luminance, through the mode that detects output voltage, turn-off control is carried out to the dimming signal of signal output circuit to the MOS pipe output of adjusting luminance through comparison control circuit, thereby realize the short-circuit monitoring and the protect function of secondary output of dimming circuit, this circuit is reliable effective, and need not isolation circuit, be applicable to extensive lamp area constant voltage output circuit, can be when the short circuit appears in constant voltage output circuit's secondary output, in time last the turn-off to the MOS pipe of adjusting luminance, great improvement dimming circuit's reliability, the cost in the aspect of dimming circuit short-circuit protection has been reduced.
Drawings
Fig. 1 is a circuit diagram of a constant voltage output dimming circuit of a lamp source according to an embodiment of the present application.
Fig. 2 is a block diagram of a constant voltage output dimming circuit of a lamp source according to an embodiment of the present application.
Wherein:
the comparison control circuit is 10, the signal output circuit is 20, the comparison circuit is 11, and the switch circuit is 12.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Examples
The embodiment provides a light source constant voltage output dimming circuit, and the dimming circuit is mainly used for dimming in the process of realizing light source constant voltage output, wherein the dimming circuit has a stimulation short circuit monitoring protection function, when the secondary output of the constant voltage output circuit has abnormal conditions such as short circuit, the short circuit monitoring protection function can be realized through the comparison control circuit 10 in the dimming circuit, and then when the secondary output is abnormal, the dimming circuit is protected by switching off.
Specifically, the lamp source constant voltage output dimming circuit of the present embodiment includes a constant voltage output circuit and a dimming control circuit; the constant voltage output circuit comprises a lamp source and a constant voltage driving power supply, and the constant voltage driving power supply is used for realizing constant voltage driving of the lamp source. And in the aspect of the dimming control circuit, it is disposed at the output side of the constant voltage output circuit for implementing dimming of the lamp source, and more specifically, the dimming control circuit includes a dimming MOS transistor Q1, a signal output circuit 20, and a comparison control circuit 10. In terms of functions of each circuit and component, the dimming MOS transistor Q1 and the signal output circuit 20 are added to the lamp output terminal in combination, and a dimming function can be realized by the cooperation of the two, wherein the signal output circuit 20 is configured to output a PWM dimming signal (Pulse width modulation) to the dimming MOS transistor Q1. It should be noted that, in the present embodiment, the signal output circuit 20 is provided with a single chip, and the output control of the PWM dimming signal is realized by the single chip.
On the other hand, the comparison control circuit 10 is mainly used for collecting and detecting the output voltage of the drain of the dimming MOS transistor Q1, that is, the output terminal, so as to determine whether there is an abnormality according to the voltage thereof, and in an abnormal state, the comparison control circuit continuously turns off the dimming signal output from the signal output circuit 20 to the dimming MOS transistor Q1, thereby implementing an output short-circuit protection function.
In terms of specific circuit connection, the source and the drain of the dimming MOS transistor Q1 are connected between the output terminal and the ground terminal of the constant voltage dimming circuit, respectively, and the gate thereof is connected to the signal output circuit 20. It should be noted that the dimming MOS transistor Q1 is an NMOS transistor, and when the signal output circuit 20 outputs the dimming signal, the dimming MOS transistor Q1 is turned on, and when the dimming MOS transistor Q1 is at a low level, it is turned off.
In the comparison control circuit 10, a detection resistor R1 is arranged between the dimming MOS transistor Q1 and the ground terminal; the detection end of the comparison control circuit 10 is connected to the drain of the dimming MOS transistor Q1, the output current of the drain of the dimming MOS transistor Q1 is converted into a voltage signal on the detection resistor R1, and the comparison control circuit 10 collects the voltage signal through the detection end and realizes subsequent comparison through the voltage signal. The output end of the comparison control circuit 10 is connected with the signal output circuit 20, the comparison control circuit 10 monitors the collected voltage signal, and when the voltage signal exceeds the preset voltage, the signal output circuit 20 outputs a signal to the dimming MOS transistor Q1 to be continuously turned off. It should be noted that the preset voltage is obtained by inputting a reference voltage to the reference terminal of the comparison control circuit 10.
The benefit of this embodiment lies in, this dimming circuit is through setting up detection resistance R1 at the MOS pipe Q1 output of adjusting luminance, through the mode that detects output voltage, through comparison control circuit 10 to signal output circuit 20 to the signal of adjusting luminance that adjusts luminance MOS pipe Q1 is exported turn-off control, thereby realize the short circuit monitoring and the protect function of the secondary output of dimming circuit, this circuit is reliable effective, and need not isolation circuit, can appear when short circuit in the secondary output of constant voltage output circuit, in time last the shutoff to MOS pipe Q1 of adjusting luminance, great improvement dimming circuit's reliability, the cost in the aspect of dimming circuit short circuit protection has been reduced.
Some embodiments of the present dimming circuit are as follows:
in the aspect of the comparison control circuit 10, in some embodiments, the comparison control circuit 10 includes a comparison circuit 11 and a switch circuit 12, where the comparison circuit 11 is used to collect and compare the voltage at the output terminal of the dimming MOS transistor Q1, and adjust the output at the output terminal thereof according to the comparison result. The switch circuit 12 is configured to pull down the voltage at the gate of the dimming MOS transistor Q1 when the output terminal of the comparison circuit 11 outputs a high level, so as to complete the turn-off of the dimming MOS transistor Q1. The comparator circuit 11 has a detection terminal, a reference terminal, and an output terminal, and the output terminal thereof determines whether to output a high level by comparing the detection terminal with the reference terminal. The switch circuit 12 has a control terminal, an input terminal and an output terminal, the control terminal is connected to the output terminal of the comparison circuit 11, and the input terminal and the output terminal are conducted or not according to the high-low level input of the control terminal. In terms of specific connection, the detection end of the comparison circuit 11 is connected with the drain electrode of the dimming MOS transistor Q1, the reference end is connected with an external reference voltage output end, and the output end is connected with the control end of the switch circuit 12; the input end and the output end of the switch circuit 12 are respectively connected with the output end of the signal output circuit 20 and the ground wire, and the connection between the signal output circuit 20 and the ground wire is controlled according to the input of the comparison circuit 11, so that the signal output circuit 20 can output signals to the dimming MOS transistor Q1 to be switched off.
Preferably, a self-locking module is disposed between the output end and the detection end of the comparison circuit 11, when the voltage collected by the detection end of the comparison circuit 11 is greater than the reference voltage, the output end of the comparison circuit 11 outputs a high level, and at this time, the output end of the comparison circuit 11 makes the detection end of the comparison circuit 11 at a high potential through the self-locking module, so as to finally realize continuous output of the high level at the output end of the comparison circuit 11. The high voltage means that the voltage at the detection terminal of the comparison circuit 11 is continuously greater than the reference voltage. More preferably, the self-locking module includes a diode D1, an input terminal and an output terminal of the diode D1 are respectively connected to the output terminal and the detection terminal of the comparator U1, and the diode D1 is configured to realize unidirectional conduction between the output terminal and the detection terminal of the comparison circuit 11.
In some embodiments, the comparing circuit 11 includes a comparator U1, and the comparator U1 is mainly used for comparing the collected voltage signals and implementing the voltage output by the output terminal thereof according to the comparison result. Specifically, the detection end of the comparator U1 is connected to the drain of the dimming MOS transistor Q1, the reference end is connected to an external reference voltage output end, the power supply end is connected to an external input power supply, the output end is connected to the control end of the switch circuit 12, and the ground end is grounded. When the voltage signal collected by the detection end is greater than the reference voltage, the output end is conducted with the power supply end, and the voltage output of the output end is realized.
Preferably, the comparison circuit 11 further includes a filter resistor R2 disposed at the detection end, and the filter resistor R2 is configured to filter the voltage signal collected by the detection end, so as to filter noise interference.
In some embodiments, the switching circuit 12 includes a first transistor Q2; the base of the first transistor Q2 is connected to the output terminal of the comparison circuit 11, and the collector and emitter are connected to the output terminal of the signal output circuit 20 and the ground, respectively. Preferably, the first transistor Q2 is an NPN transistor.
Also preferably, the voltage regulating circuit further comprises a first voltage regulating resistor R3 and a second voltage regulating resistor R4; the first voltage regulating resistor R3 is arranged between the base of the first triode Q2 and the output end of the comparison circuit 11; the second voltage regulating resistor R4 is connected in series between the base of the first triode Q2 and the ground wire. The first voltage regulating resistor R3 and the second voltage regulating resistor R4 are used for providing a proper working voltage and current for the first transistor Q2.
For better use experience, a specific structure and a working flow of the voltage regulating circuit in this embodiment are provided, specifically, referring to fig. 1, the comparison circuit 11 includes a comparator U1, the reference voltage output circuit provides a reference voltage Vref for the negative terminal of the comparator U1, an output current of the constant voltage output circuit is converted into a voltage signal on the detection resistor R1 through the lamp source and the dimming MOS transistor Q1, and the voltage signal enters the positive terminal of the comparator U1 through the filter resistor R2. Diode D1 is an output positive feedback diode D1. More specifically, the detection resistor R1 may have different values, preferably 1-20m Ω, according to different circuit output currents, the filter resistor R2 has a value of 10-100K, and the reference voltage Vref preferably has a value of 0.5-1.5V. As a preferred implementation value, the detection resistor R1 takes a value of 10m Ω, the filter resistor R2 takes a value of 10K, and the reference voltage Vref takes a value of 1V.
Under the normal working state, because the resistance value of the current detection resistor R1 is very small, the voltage in the normal working state is far lower than the reference voltage Vref, when the comparator U1 detects that the voltage signal is lower than the reference voltage Vref arranged on the negative terminal of the comparator U1, the output of the comparator U1 is set to be low level, and the base of the first triode Q2 is pulled down to be in an off state. At this time, the dimming MOS transistor Q1 is in a normal operating state.
In the short circuit state, when the short circuit state occurs, the instantaneous current flowing through the loop during the short circuit is very large and far exceeds the current in the normal working state. At this time, the voltage across the sense resistor R1 exceeds the set reference voltage Vref, and when the comparator U1 detects that the voltage signal is higher than the reference voltage Vref set at the negative terminal of the comparator U1, the comparator U1 outputs a high level. The high level of the output is fed back to the positive end of the comparator U1, namely the detection end, through the diode D1, the positive end of the comparator U1 is pulled high all the time, positive feedback is achieved, and the output is locked to be the high level. After the comparator U1 outputs high level, the first triode Q2 is conducted, and the dimming MOS tube Q1 connected to the collector of the triode is driven to be pulled down, so that the MOS tube is disconnected, and the output short-circuit protection function is realized.
It should be understood that the above examples of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.
Claims (10)
1. A lamp source constant voltage output dimming circuit is characterized by comprising a constant voltage output circuit and a dimming control circuit; the dimming control circuit is arranged on the output side of the constant voltage output circuit and is used for realizing dimming of the lamp source; the dimming control circuit comprises a dimming MOS tube, a signal output circuit and a comparison control circuit; the source electrode and the drain electrode of the dimming MOS tube are respectively connected between the output end and the grounding end of the constant-voltage dimming circuit, and the grid electrode of the dimming MOS tube is connected with the signal output circuit; a detection resistor is arranged between the dimming MOS tube and the grounding end; the detection end of the comparison control circuit is connected to the drain electrode of the dimming MOS tube to collect the output voltage of the drain electrode of the dimming MOS tube, the output end of the comparison control circuit is connected with the signal output circuit, the comparison control circuit monitors the collected voltage, and when the voltage exceeds the preset voltage, the signal output circuit can continuously turn off the output signal of the dimming MOS tube.
2. The lamp source constant voltage output dimming circuit according to claim 1, wherein the comparison control circuit comprises a comparison circuit and a switching circuit; the detection end of the comparison circuit is connected with the drain electrode of the dimming MOS tube, the reference end of the comparison circuit is connected with an external reference voltage output end, and the output end of the comparison circuit is connected with the control end of the switch circuit; the input end and the output end of the switch circuit are respectively connected with the output end of the signal output circuit and the ground wire, and the conduction between the signal output circuit and the ground wire is controlled according to the input of the comparison circuit, so that the signal output circuit is turned off when outputting signals to the dimming MOS tube.
3. The lamp source constant voltage output dimming circuit according to claim 2, wherein a self-locking module is arranged between the output end and the detection end of the comparison circuit; when the output end of the comparison circuit outputs a high level, the continuous output of the high level is realized through the self-locking module.
4. The lamp source constant voltage output dimming circuit of claim 3, wherein the self-locking module comprises a diode, and an input terminal and an output terminal of the diode are respectively connected with the output terminal and the detection terminal of the comparison circuit.
5. The lamp source constant voltage output dimming circuit according to claim 2, wherein the comparison circuit comprises a comparator, a detection terminal of the comparator is connected to a drain electrode of the dimming MOS transistor, a reference terminal is connected to an external reference voltage output terminal, a power supply terminal is connected to an external input power supply, and an output terminal is connected to a control terminal of the switching circuit.
6. The lamp source constant voltage output dimming circuit of claim 2, wherein the comparison circuit further comprises a filter resistor disposed on the detection terminal.
7. The lamp source constant voltage output dimming circuit according to any one of claims 2 to 6, wherein the switching circuit comprises a first transistor; and the base electrode of the first triode is connected with the output end of the comparison circuit, and the collector electrode and the emitter electrode are respectively connected with the output end of the signal output circuit and the ground wire.
8. The lamp source constant voltage output dimming circuit of claim 7, wherein the first transistor is an NPN transistor.
9. The lamp source constant voltage output dimming circuit of claim 7, further comprising a first voltage regulating resistor and a second voltage regulating resistor; the first voltage regulating resistor is arranged between the base electrode of the first triode and the output end of the comparison circuit; the second voltage regulating resistor is connected between the base electrode of the first triode and the ground wire in series.
10. The lamp source constant voltage output dimming circuit of claim 1, wherein the signal output circuit is configured to output a PWM dimming signal to the dimming MOS transistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202022715542.0U CN213783662U (en) | 2020-11-19 | 2020-11-19 | Constant voltage output dimming circuit of lamp source |
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| CN202022715542.0U CN213783662U (en) | 2020-11-19 | 2020-11-19 | Constant voltage output dimming circuit of lamp source |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112543538A (en) * | 2020-11-19 | 2021-03-23 | 惠州市西顿工业发展有限公司 | Constant voltage output dimming circuit of lamp source |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112543538A (en) * | 2020-11-19 | 2021-03-23 | 惠州市西顿工业发展有限公司 | Constant voltage output dimming circuit of lamp source |
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