CN114501733B - LED constant current drive circuit with open circuit detection function - Google Patents
LED constant current drive circuit with open circuit detection function Download PDFInfo
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- CN114501733B CN114501733B CN202210055394.5A CN202210055394A CN114501733B CN 114501733 B CN114501733 B CN 114501733B CN 202210055394 A CN202210055394 A CN 202210055394A CN 114501733 B CN114501733 B CN 114501733B
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- resistor
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- constant current
- diode
- open circuit
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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
Abstract
The invention discloses an LED constant current driving circuit with an open circuit detection function, which comprises an input reverse connection protection circuit, an LED lamp string circuit, a constant current driving unit, an open circuit detection unit and a logic judgment unit, wherein the input reverse connection protection circuit, the LED lamp string circuit, the constant current driving unit, the open circuit detection unit and the logic judgment unit are sequentially connected.
Description
Technical Field
The invention relates to the technical field of driving of LED lamp strings, in particular to an LED constant current driving circuit with an open circuit detection function.
Background
At present, the LED lamp string of the glide slope indicator lamp box is driven by adopting a power supply positive end constant current control technology, the LED lamp string is connected to a power supply negative end, most of active equipment does not have an open circuit detection function, few new equipment adopts a series detection resistor and isolation operational amplifier scheme, a circuit is relatively complex, and the equipment cost and the circuit complexity are additionally increased by adopting current Hall detection.
Disclosure of Invention
The invention aims to provide an LED constant current driving circuit with an open circuit detection function, so as to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the LED constant current driving circuit with the open circuit detection function comprises an input reverse connection protection circuit, an LED lamp string circuit, a constant current driving unit, an open circuit detection unit and a logic judgment unit, wherein the input reverse connection protection circuit, the LED lamp string circuit, the constant current driving unit, the open circuit detection unit and the logic judgment unit are sequentially connected.
As a further technical scheme of the invention: the input reverse connection protection circuit comprises a fuse F1 and a diode D1, the LED lamp string circuit comprises an LED lamp string D2-Dn and a diode Dr, the constant current driving unit comprises a chip U1 and a resistor Rs, the open circuit detection unit comprises a resistor R1, a resistor R2, a capacitor C2, a resistor Rb, a resistor Rc, a capacitor C4 and a triode Q1, the logic judgment unit comprises a chip U2, one end of the fuse F1 is connected with PWM_IN, the other end of the fuse F1 is connected with an anode of the diode D1, a cathode of the diode D1 is connected with the capacitor C1, the resistor R1, the LED lamp string D2-Dn and a cathode of the diode Dr, the other end of the resistor R1 is connected with the resistor R2, the capacitor C2 and one input end of the chip U2, the other end of the LED lamp string D2-Dn is connected with the anode of the diode Dr, the capacitor C3 and the input end IN of the chip U1, the output end of the chip U1 is connected with the resistor Rb and the resistor Q1, the other end of the resistor Rb is connected with a base of the triode Q1, the other end of the resistor C4 is connected with the other end of the resistor C2 and the other end of the resistor C2, and the other end of the resistor C2 is connected with the collector of the resistor C1 and the resistor R1.
As a further technical scheme of the invention: the triode Q1 is an NPN triode.
As a further technical scheme of the invention: the diode Dr is a zener diode.
As a further technical scheme of the invention: the resistor Rs is a current sampling resistor.
As a further technical scheme of the invention: the resistor R1 and the resistor R2 form a current sampling circuit.
Compared with the prior art, the invention has the beneficial effects that: the invention has simple circuit structure, reduces the use amount of electronic elements by more than one third compared with the prior art, and reduces the cost of a core circuit by more than two thirds.
Drawings
Fig. 1 is a circuit diagram of the present invention.
Fig. 2 is a block diagram of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1: referring to fig. 2, an LED constant current driving circuit with an open circuit detection function includes an input reverse connection protection circuit, an LED string light circuit, a constant current driving unit, an open circuit detection unit and a logic judgment unit, wherein the input reverse connection protection circuit, the LED string light circuit, the constant current driving unit, the open circuit detection unit and the logic judgment unit are sequentially connected.
The input reverse connection protection circuit comprises a fuse F1 and a diode D1, the LED lamp string circuit comprises an LED lamp string D2-Dn and a diode Dr, the constant current driving unit comprises a chip U1 and a resistor Rs, the open circuit detection unit comprises a resistor R1, a resistor R2, a capacitor C2, a resistor Rb, a resistor Rc, a capacitor C4 and a triode Q1, the logic judgment unit comprises a chip U2, one end of the fuse F1 is connected with PWM_IN, the other end of the fuse F1 is connected with an anode of the diode D1, a cathode of the diode D1 is connected with the capacitor C1, the resistor R1, the LED lamp string D2-Dn and a cathode of the diode Dr, the other end of the resistor R1 is connected with the resistor R2, the capacitor C2 and one input end of the chip U2, the other end of the LED lamp string D2-Dn is connected with the anode of the diode Dr, the capacitor C3 and the input end IN of the chip U1, the output end of the chip U1 is connected with the resistor Rb and the resistor R1, the other end of the resistor R1 is connected with the base of the triode Q1, the other end of the triode Q1 is connected with the other end of the resistor C4 and the other end of the capacitor C2 and the resistor C2 is connected with the other end of the resistor C2, and the other end of the resistor C2 is connected with the other end of the resistor C1 and the resistor C2 is connected with the other end of the resistor C.
Wherein, the resistor Rs is a current sampling resistor. The resistor R1 and the resistor R2 form a current sampling circuit.
According to the invention, a constant current circuit is constructed by using the chip U1, when Vin-Vout is more than 2V and Vout-Vadj=1.25V, the circuit current I= (Vout-Vadj)/Rs=1.25/Rs (A) is only related to the sampling resistor RS, and the circuit does not change along with the input voltage and the LED string voltage, and enters a constant current state.
When the LED lamp string works normally, the voltage at two ends of the current sampling resistor Rs is a fixed value of 1.25V, the triode Q1 is conducted, and the collector electrode of the triode Q is output with low level; when the LED string is open, no current flows through the sampling resistor Rs, the voltage at two ends is 0V, the triode Q1 is cut off, and the collector electrode outputs high level. The working state of the LED lamp string can be detected by detecting the collector output state of the triode Q1.
Because the constant current circuit is arranged at the low voltage end of the power supply, the resistor Rs can be used for current sampling of the constant current control circuit and current sampling of open circuit detection, so that a common design is realized, and the circuit design is simplified.
Example 2, based on example 1: the model of the chip U1 is CW117. The model of the chip U1 is LM117. The triode Q1 is an NPN triode. The diode Dr is a zener diode.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.
Claims (5)
1. The LED constant current driving circuit with the open circuit detection function comprises an input reverse connection protection circuit, an LED lamp string circuit, a constant current driving unit, an open circuit detection unit and a logic judgment unit, and is characterized in that the input reverse connection protection circuit, the LED lamp string circuit, the constant current driving unit, the open circuit detection unit and the logic judgment unit are sequentially connected;
the input reverse connection protection circuit comprises a capacitor C1, a fuse F1 and a diode D1, the LED lamp string circuit comprises an LED lamp string D2-Dn and a diode Dr, the constant current driving unit comprises a capacitor C3, a chip U1 and a resistor Rs, the open circuit detection unit comprises a resistor R1, a resistor R2, a capacitor C2, a resistor Rb, a resistor Rc, a capacitor C4 and a triode Q1, the logic judgment unit comprises a chip U2, one end of the fuse F1 is connected with PWM_IN, the other end of the fuse F1 is connected with an anode of the diode D1, a cathode of the diode D1 is connected with the capacitor C1, the resistor R1, the LED lamp string D2-Dn and a cathode of the diode Dr, the other end of the resistor R1 is connected with the resistor R2, the capacitor C2 and one input end of the chip U2, the other end of the resistor C3 is connected with the anode of the diode Dr, the capacitor C3 and the input end IN of the chip U1, the output end of the chip U1 is connected with the resistor Rb and the resistor Rs, the other end of the resistor R1 is connected with the other end of the resistor C1 and the other end of the resistor C2 is connected with the resistor C2 and the other end of the resistor C2.
2. The LED constant current driving circuit with an open circuit detection function according to claim 1, wherein the transistor Q1 is an NPN transistor.
3. The LED constant current driving circuit with an open circuit detection function according to claim 1, wherein the diode Dr is a zener diode.
4. The LED constant current driving circuit with an open circuit detection function according to claim 1, wherein the resistor Rs is a current sampling resistor.
5. The LED constant current driving circuit with the open circuit detection function according to claim 1, wherein the resistor R1 and the resistor R2 constitute a current sampling circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210055394.5A CN114501733B (en) | 2022-01-18 | 2022-01-18 | LED constant current drive circuit with open circuit detection function |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210055394.5A CN114501733B (en) | 2022-01-18 | 2022-01-18 | LED constant current drive circuit with open circuit detection function |
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| Publication Number | Publication Date |
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| CN114501733A CN114501733A (en) | 2022-05-13 |
| CN114501733B true CN114501733B (en) | 2023-10-13 |
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| CN202210055394.5A Active CN114501733B (en) | 2022-01-18 | 2022-01-18 | LED constant current drive circuit with open circuit detection function |
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Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116189581A (en) * | 2023-04-27 | 2023-05-30 | 杭州视芯科技股份有限公司 | LED open circuit detection method and circuit, and LED driving method and circuit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102970791A (en) * | 2012-11-01 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Light-emitting diode (LED) constant current driving circuit and LED lamp |
| US8710745B1 (en) * | 2012-12-11 | 2014-04-29 | Unity Opto Technology Co., Ltd. | LED drive circuit |
| CN204615446U (en) * | 2015-04-29 | 2015-09-02 | 爱玛科技股份有限公司 | A kind of lithium battery charger with battery capacity indication and defencive function |
| CN109246889A (en) * | 2018-09-26 | 2019-01-18 | 华域视觉科技(上海)有限公司 | The LED drive circuit and its driving method and storage medium of DC-DC and linear combination |
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- 2022-01-18 CN CN202210055394.5A patent/CN114501733B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102970791A (en) * | 2012-11-01 | 2013-03-13 | 深圳创维－Rgb电子有限公司 | Light-emitting diode (LED) constant current driving circuit and LED lamp |
| US8710745B1 (en) * | 2012-12-11 | 2014-04-29 | Unity Opto Technology Co., Ltd. | LED drive circuit |
| CN204615446U (en) * | 2015-04-29 | 2015-09-02 | 爱玛科技股份有限公司 | A kind of lithium battery charger with battery capacity indication and defencive function |
| CN109246889A (en) * | 2018-09-26 | 2019-01-18 | 华域视觉科技(上海)有限公司 | The LED drive circuit and its driving method and storage medium of DC-DC and linear combination |
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| CN114501733A (en) | 2022-05-13 |
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