Circuit for solving multi-light-bead short-circuit anomaly

Abstract

The application relates to a circuit for solving a multi-lamp-bead short-circuit abnormality. The circuit for solving the multi-lamp-bead short-circuit abnormality comprises a master control chip IC900 and a lamp control module. The lamp control module comprises a dimming unit, a conduction unit and a detection unit. The dimming unit is electrically connected with the master control chip IC900. The conduction unit comprises a triode Q901, a triode Q906 and a resistor R925. The triode Q901 is electrically connected with the master control chip IC900. The triode Q906 is electrically connected with a first end of the resistor R925. A second end of the resistor R925 is electrically connected with the triode Q901. According to the scheme, the dimming unit can be prevented from being in a working state after a lamp bead appears a short circuit, so that damage is avoided.

Description

Technical Field

[0001] This utility model relates to the field of circuit design technology, and in particular to a circuit for solving the problem of short circuit in multiple LEDs. Background Technology

[0002] Currently, electronic devices such as televisions and monitors require a two-in-one switching power supply to power the motherboard and LED backlight. The backlight circuitry typically uses a boost converter. However, in a single-channel backlight boost converter circuit, if multiple LEDs in the LED strip fail and an abnormal short circuit occurs, the strip voltage will drop. When the strip voltage falls below the pre-boost voltage, the backlight dimming MOSFET does not stop working. The excess voltage is forced onto the dimming MOSFET, increasing its losses and temperature; under extreme conditions, this can lead to damage. Utility Model Content

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a circuit that solves the problem of multiple LED short circuits, thus preventing the dimming unit from continuing to work after a short circuit occurs in the LEDs, which could lead to damage.

[0004] The objective of this utility model is achieved through the following technical solution:

[0005] The first aspect of this application provides a circuit for resolving short circuit abnormalities of multiple LED beads, including: a main control chip IC900; and a lamp control module including a dimming unit, a conduction unit, and a detection unit. The dimming unit is electrically connected to the main control chip IC900. The conduction unit includes transistors Q901 and Q906 and a resistor R925. Transistor Q901 is electrically connected to the main control chip IC900, transistor Q906 is electrically connected to the first terminal of resistor R925, and the second terminal of resistor R925 is electrically connected to transistor Q901.

[0006] The dimming unit includes a MOS transistor Q950 and a resistor R950. The first end of the MOS transistor Q950 is electrically connected to the first end of the resistor R950, and the second end of the resistor R950 is electrically connected to the main control chip IC900.

[0007] The detection unit includes resistors R904, R909, and R913. Resistor R904 is electrically connected to the first end of resistor R909, the second end of resistor R909 is electrically connected to the first end of resistor R913, and the second end of resistor R913 is grounded.

[0008] The conducting unit also includes a resistor R918 and a capacitor C902. The first end of the resistor R918 is electrically connected to the first end of the resistor R913, and the second end of the resistor R918 is electrically connected to the first end of the capacitor C902. Both the first and second ends of the capacitor C902 are electrically connected to the transistor Q901.

[0009] The conduction unit also includes a diode D902, the first end of which is electrically connected to the transistor Q901, and the second end of which is electrically connected to the main control chip IC900.

[0010] The lighting control module also includes a boost unit, which includes an inductor L900, a MOSFET Q900, a diode D900, a ferrite bead FB900, and a capacitor E900. The first terminal of the inductor L900 is electrically connected to the first terminals of the MOSFET Q900 and the diode D900, respectively. The second terminal of the diode D900 is electrically connected to the first terminal of the ferrite bead FB900. The second terminal of the ferrite bead FB900 is electrically connected to the first terminal of the capacitor E900, and the second terminal of the capacitor E900 is grounded.

[0011] The lighting control module also includes an input port, which is electrically connected to the second terminal of the inductor L900.

[0012] It also includes an LED output terminal, which is electrically connected to the resistor R904.

[0013] The boost unit further includes a resistor R903, a diode D901, and a resistor R906. The first end of the resistor R903 is electrically connected to the first end of the MOSFET Q900 and the first end of the diode D901, respectively. The second end of the resistor R903 is electrically connected to the second end of the diode D901, and the first end of the resistor R906 is electrically connected to the second end of the resistor R903 and the second end of the diode D901, respectively. The second end of the resistor R906 is electrically connected to the main control chip IC900.

[0014] The boost unit also includes a resistor R907, the first end of which is electrically connected to the MOSFET Q900, and the second end of which is electrically connected to the first end of the diode D901.

[0015] Compared with the prior art, the present invention has at least the following advantages:

[0016] This application detects the LED strip voltage through a detection unit. When the LED strip voltage is lower than the set value, the chip protection is triggered by switching the conduction unit on and off, thereby stopping the operation of the dimming unit. This prevents the dimming unit from continuing to operate after a short circuit in the LED beads, which could lead to damage. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below.

[0018] Figure 1 This is a circuit diagram illustrating the solution to the short circuit problem of multiple LED beads in one embodiment of the present invention. Detailed Implementation

[0019] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0020] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] Televisions, monitors, and other electronic devices require a two-in-one switching power supply to power the motherboard and LED backlight. The backlight circuitry typically uses a boost converter. However, in a single-channel backlight boost converter circuit, if multiple LEDs in the LED strip fail and an abnormal short circuit occurs, the strip voltage will drop. When the strip voltage falls below the pre-boost voltage, the backlight dimming MOSFET does not stop working. The excess voltage is forced onto the dimming MOSFET, increasing its losses and temperature; under extreme conditions, this can lead to damage.

[0023] To address the aforementioned issues, this application provides a circuit for resolving multi-LED short-circuit anomalies, which can prevent the dimming unit from continuing to operate after an LED short circuit, thus preventing damage.

[0024] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.

[0025] Please see Figure 1 A circuit for resolving short circuits in multiple LEDs includes: a main control chip IC900 and a lighting control module. The lighting control module includes a dimming unit, a conduction unit, and a detection unit. The dimming unit is electrically connected to the main control chip IC900. The conduction unit includes transistors Q901 and Q906 and a resistor R925. Transistor Q901 is electrically connected to the main control chip IC900. Transistor Q906 is electrically connected to the first terminal of resistor R925, and the second terminal of resistor R925 is electrically connected to transistor Q901.

[0026] It should be noted that this application detects the LED strip voltage through a detection unit. When the LED strip voltage is lower than the set value, the chip protection is triggered by switching the conduction unit on and off, thereby stopping the operation of the dimming unit. This prevents the dimming unit from continuing to operate after a short circuit in the LED beads, which could lead to damage.

[0027] See Figure 1 In one embodiment, the dimming unit includes a MOSFET Q950 and a resistor R950. The first end of the MOSFET Q950 is electrically connected to the first end of the resistor R950, and the second end of the resistor R950 is electrically connected to the main control chip IC900.

[0028] It should be noted that resistor R950 is the drive resistor for MOSFET Q950.

[0029] See Figure 1 In one embodiment, the detection unit includes resistors R904, R909, and R913. Resistor R904 is electrically connected to the first end of resistor R909, the second end of resistor R909 is electrically connected to the first end of resistor R913, and the second end of resistor R913 is grounded.

[0030] It should be noted that resistors R904, R909, and R913 are voltage divider resistors.

[0031] See Figure 1In one embodiment, the conduction unit further includes a resistor R918 and a capacitor C902. The first terminal of resistor R918 is electrically connected to the first terminal of resistor R913, and the second terminal of resistor R918 is electrically connected to the first terminal of capacitor C902. Both the first and second terminals of capacitor C902 are electrically connected to transistor Q901. Specifically, the conduction unit also includes a diode D902. The first terminal of diode D902 is electrically connected to transistor Q901, and the second terminal of diode D902 is electrically connected to the main control chip IC900.

[0032] It should be noted that resistor R918 is a current-limiting resistor and capacitor C902 is a filter capacitor.

[0033] See Figure 1 In one embodiment, the lighting control module further includes a boost unit, which includes an inductor L900, a MOSFET Q900, a diode D900, a ferrite bead FB900, and a capacitor E900. The first terminal of the inductor L900 is electrically connected to the first terminals of the MOSFET Q900 and the diode D900, respectively. The second terminal of the diode D900 is electrically connected to the first terminal of the ferrite bead FB900. The second terminal of the ferrite bead FB900 is electrically connected to the first terminal of the capacitor E900. The second terminal of the capacitor E900 is grounded.

[0034] It should be noted that L900A, L900B, L900C, L900D, L900E, L900F, and L900G are all electrical connection points of inductor L900. Inductor L900 is a boost inductor, while diode D900, ferrite bead FB900, and capacitor E900 serve as rectification and filtering components.

[0035] See Figure 1 In one embodiment, the lighting control module further includes an input port, which is electrically connected to the second terminal of the inductor L900.

[0036] It should be noted that the input port is VLEDIN, and the voltage is input from VLEDIN, and then boosted through inductor L900, MOSFET Q900, diode D900, ferrite bead FB900 and capacitor E900.

[0037] See Figure 1 In one embodiment, it also includes an LED output terminal, which is electrically connected to resistor R904.

[0038] It should be noted that the LED output terminal is VLED+.

[0039] See Figure 1In one embodiment, the boost unit further includes a resistor R903, a diode D901, and a resistor R906. The first end of the resistor R903 is electrically connected to the first end of the MOSFET Q900 and the first end of the diode D901, respectively. The second end of the resistor R903 is electrically connected to the second end of the diode D901, and the first end of the resistor R906 is electrically connected to the second end of the resistor R903 and the second end of the diode D901, respectively. The second end of the resistor R906 is electrically connected to the main control chip IC900.

[0040] It should be noted that resistors R903 and R906 are driving resistors, and diode D901 is used to adjust the value of the turn-off resistor. Specifically, when the MOSFET Q900 is turned on, the resistance is the sum of resistors R906 and R903. When the MOSFET Q900 is turned off, diode D901 short-circuits resistor R903, and the resistance is then R906. This achieves the effect of a large turn-on resistance and a small turn-off resistance for the MOSFET Q900.

[0041] See Figure 1 In one embodiment, the boost unit further includes a resistor R907, the first end of which is electrically connected to the MOSFET Q900, and the second end of which is electrically connected to the first end of the diode D901.

[0042] It should be noted that resistor R907 is a discharge resistor, used to promptly release the energy of MOSFET Q900.

[0043] The circuit principle is explained below:

[0044] By controlling the main control chip IC900, boost inductor L900, MOSFET Q900, and diode D900, the VLEDIN voltage is increased to the VLED+ voltage. Then, the MOSFET Q950 adjusts the current to regulate the backlight brightness. However, in abnormal conditions, if some LED chips fail or multiple short circuits occur, the input voltage VLEDIN becomes higher than VLED+. MOSFET Q950 remains continuously conducting, resulting in significant power dissipation and potential temperature rise, which could pose a safety hazard. By adding external circuitry, resistors R904, R909, and R913 are used to detect the VLED+ voltage. When the voltage at the first terminal of resistor R913 is lower than the drive voltage of transistor Q901, the voltage divided by resistor R913 is used to provide a changing level voltage to the base (B) of transistor Q901. The emitter (E) voltage of transistor Q901 is the voltage value of Vref minus the voltage between the collector (C) and emitter (E) of transistor Q906. When the base voltage of transistor Q901 is lower than the voltage value of Vref minus the voltage between the collector (C) and emitter (E) of MOSFET Q906, and then minus the voltage value between the base and emitter (B) of transistor Q901, current begins to flow to the base of transistor Q901, and transistor Q901 begins to conduct. At this time, the voltage is provided to the OVP pin (Pin 3) of the main control chip IC900 through diode D902. This pin is the overvoltage protection pin of the main control chip IC900. Triggering this protection pin will cause the Pin16 gate pin of the boost control main control chip IC900 to stop working and the Pin15 Dimout pin to output a low level, causing the MOSFET Q905 to stop working.

[0045] The solution of this application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of each embodiment have different focuses; for parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments. Those skilled in the art should also understand that the actions and modules involved in the specification are not necessarily essential to this application. Furthermore, it is understood that the steps in the method of this application embodiment can be adjusted, combined, and deleted according to actual needs, and the modules in the device of this application embodiment can be combined, divided, and deleted according to actual needs.

[0046] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A circuit for resolving short-circuit abnormalities in multiple LED beads, characterized in that, include: Main control chip IC900; The lighting control module includes a dimming unit, a conduction unit, and a detection unit. The dimming unit is electrically connected to the main control chip IC900. The conduction unit includes transistors Q901 and Q906 and resistor R925. Transistor Q901 is electrically connected to the main control chip IC900. Transistor Q906 is electrically connected to the first end of resistor R925, and the second end of resistor R925 is electrically connected to transistor Q901.

2. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 1, characterized in that, The dimming unit includes a MOS transistor Q950 and a resistor R950. The first end of the MOS transistor Q950 is electrically connected to the first end of the resistor R950, and the second end of the resistor R950 is electrically connected to the main control chip IC900.

3. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 2, characterized in that, The detection unit includes resistors R904, R909, and R913. Resistor R904 is electrically connected to the first end of resistor R909, the second end of resistor R909 is electrically connected to the first end of resistor R913, and the second end of resistor R913 is grounded.

4. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 3, characterized in that, The conducting unit also includes a resistor R918 and a capacitor C902. The first end of the resistor R918 is electrically connected to the first end of the resistor R913, and the second end of the resistor R918 is electrically connected to the first end of the capacitor C902. Both the first and second ends of the capacitor C902 are electrically connected to the transistor Q901.

5. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 1, characterized in that, The conduction unit also includes a diode D902, the first end of which is electrically connected to the transistor Q901, and the second end of which is electrically connected to the main control chip IC900.

6. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 5, characterized in that, The lighting control module also includes a boost unit, which includes an inductor L900, a MOSFET Q900, a diode D900, a ferrite bead FB900, and a capacitor E900. The first terminal of the inductor L900 is electrically connected to the first terminals of the MOSFET Q900 and the diode D900, respectively. The second terminal of the diode D900 is electrically connected to the first terminal of the ferrite bead FB900. The second terminal of the ferrite bead FB900 is electrically connected to the first terminal of the capacitor E900, and the second terminal of the capacitor E900 is grounded.

7. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 6, characterized in that, The lighting control module also includes an input port, which is electrically connected to the second terminal of the inductor L900.

8. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 3, characterized in that, It also includes an LED output terminal, which is electrically connected to the resistor R904.

9. The circuit for resolving short-circuit abnormalities in multiple LED beads according to claim 8, characterized in that, The boost unit further includes a resistor R903, a diode D901, and a resistor R906. The first end of the resistor R903 is electrically connected to the first end of the MOSFET Q900 and the first end of the diode D901, respectively. The second end of the resistor R903 is electrically connected to the second end of the diode D901, and the first end of the resistor R906 is electrically connected to the second end of the resistor R903 and the second end of the diode D901, respectively. The second end of the resistor R906 is electrically connected to the main control chip IC900.

10. The circuit for resolving short-circuit abnormalities of multiple LED beads according to claim 9, characterized in that, The boost unit also includes a resistor R907, the first end of which is electrically connected to the MOSFET Q900, and the second end of which is electrically connected to the first end of the diode D901.

Images