LED driving overload protection circuit

Abstract

The utility model discloses an LED drive overload protection circuit, which comprises an MOS tube Q1, an MOS tube Q2, a current detection unit, an amplification unit, a comparison unit and a charging and discharging unit, the G pole of the MOS tube Q1 and the D pole of the MOS tube Q2 are respectively and electrically connected with the drive signal end of an LED drive, the D pole of the MOS tube Q1 is electrically connected with an LED load, the S pole of the MOS tube Q1 is electrically connected with the input end of the current detection unit, and the current detection unit is electrically connected with the amplification unit. The output end of the current detection unit is electrically connected with the input end of the amplification unit, the output end of the amplification unit is electrically connected with the input end of the comparison unit, the output end of the comparison unit is electrically connected with the input end of the charging and discharging unit, one output end of the charging and discharging unit is electrically connected with the G pole of the MOS tube Q2, and the other output end of the charging and discharging unit is electrically connected with the G pole of the MOS tube Q2. And the other output end of the charging and discharging unit and the S pole of the MOS tube Q2 are respectively grounded.

Description

Technical Field

[0001] The utility model relates to the technical field of LED driving, in particular to an LED driving overload protection circuit. Background Art

[0002] Existing LED drivers generally do not have overload protection. When the LED voltage and driver voltage do not match, or when the LED power exceeds the LED driver power, the heat generated by the LED driver will rise sharply, damaging the LED driver or reducing the service life of the LED driver, and even affecting the service life of the LED. Utility Model Content

[0003] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide an LED driver overload protection circuit that effectively protects the LED driver and the load.

[0004] According to an embodiment of the present utility model, an LED driver overload protection circuit includes a MOS transistor Q1, a MOS transistor Q2, a current detection unit, an amplifying unit, a comparing unit, and a charging and discharging unit. The G pole of the MOS transistor Q1 and the D pole of the MOS transistor Q2 are respectively electrically connected to the driving signal end of the LED driver, the D pole of the MOS transistor Q1 is electrically connected to the LED load, the S pole of the MOS transistor Q1 is electrically connected to the input end of the current detection unit, the output end of the current detection unit is electrically connected to the input end of the amplifying unit, the output end of the amplifying unit is electrically connected to the input end of the comparing unit, the output end of the comparing unit is electrically connected to the input end of the charging and discharging unit, one output end of the charging and discharging unit is electrically connected to the G pole of the MOS transistor Q2, and the charging and discharging unit is electrically connected to the G pole of the MOS transistor Q2. The other output end of the element and the S pole of the MOS tube Q2 are grounded respectively; the driving signal drives the MOS tube Q1 to make the LED load normally turned on, and the current flows through the current detection unit to generate a current detection signal. The current detection signal is amplified by the amplifying unit and sent to the comparing unit to be compared with the reference signal of the comparing unit. When the LED load is normal, the amplified current detection signal is smaller than the reference signal, and the comparing unit outputs a low level, so that the MOS tube Q2 is not turned on, so that the driving signal drives the MOS tube Q1 normally; when the LED load is overloaded, the amplified current detection signal is larger than the reference signal, and the comparing unit outputs a high level to charge the charging and discharging unit, so that the MOS tube Q2 is turned on, and the driving signal is pulled down, so that the MOS tube Q1 is turned off.

[0005] The LED driver overload protection circuit according to the embodiment of the present invention has at least the following beneficial effects: when overload protection is activated, the MOS transistor Q1 is turned off and no current detection signal is generated. The signal sent to the comparison unit through the amplification unit is substantially zero, and the comparison unit outputs a low level. At this time, the charge-discharge unit discharges. When the level drops to the turn-on level of the MOS transistor Q2, the MOS transistor Q2 is turned off, restoring the drive signal and turning on the MOS transistor Q1. The current of the LED load then flows through the current detection unit again to generate a current detection signal. After amplification, the current detection signal is again compared with the reference signal of the comparison unit. If the current is greater than the reference voltage, the MOS transistor Q2 is turned off again, thus intermittently lighting up and shutting down the LED load, indicating an abnormal operation and effectively protecting the LED load and the power supply itself. When the LED load recovers, the drive signal returns to normal according to the same principle, and the LED will light up normally. Similarly, when a short circuit occurs in the LED load, the drive signal will also be pulled low, effectively protecting the MOS transistor Q1 from burning out and effectively protecting the driver from short circuit faults. When the short circuit fault is restored, the drive signal also returns to normal, and the LED will light up normally. It effectively protects LED lighting products, avoids heat damage caused by overcurrent, and extends the service life of LEDs; effectively protects LED drivers, avoids overheating and damage caused by overload, and extends the service life of LED drivers; effectively protects the driver's MOS tube from damage caused by output short circuit, reducing application risks and failure rates; effectively improves application risks, when overloaded, the LED lighting will light up and shut down at intervals, effectively prompting fault phenomena in the application, facilitating timely debugging and repair of faults.

[0006] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The following is a further description of the specific embodiments of the present invention in conjunction with the accompanying drawings;

[0008] Figure 1 This is the schematic diagram of the LED driver overload protection circuit. DETAILED DESCRIPTION

[0009] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0010] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0011] In the description of this utility model, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0012] Reference Figure 1The utility model provides an LED driver overload protection circuit, including a MOS transistor Q1, a MOS transistor Q2, a current detection unit 11, an amplifying unit 13, a comparing unit 14, and a charging and discharging unit 15. The G pole of the MOS transistor Q1 and the D pole of the MOS transistor Q2 are respectively electrically connected to the driving signal end of the LED driver, the D pole of the MOS transistor Q1 is electrically connected to the LED load, the S pole of the MOS transistor Q1 is electrically connected to the input end of the current detection unit 11, the output end of the current detection unit 11 is electrically connected to the input end of the amplifying unit 13, the output end of the amplifying unit 13 is electrically connected to the input end of the comparing unit 14, the output end of the comparing unit 14 is electrically connected to the input end of the charging and discharging unit 15, one output end of the charging and discharging unit 15 is electrically connected to the G pole of the MOS transistor Q2, and the charging and discharging unit 15 is electrically connected to the G pole of the MOS transistor Q2. The other output end of the element 15 and the S pole of the MOS transistor Q2 are grounded respectively; the driving signal drives the MOS transistor Q1 to normally conduct the LED load, and the current flows through the current detection unit 11 to generate a current detection signal. The current detection signal is amplified by the amplifying unit 13 and sent to the comparing unit 14 to be compared with the reference signal of the comparing unit 14. When the LED load is normal, the amplified current detection signal is smaller than the reference signal, and the comparing unit 14 outputs a low level, so that the MOS transistor Q2 is not conducted, so that the driving signal drives the MOS transistor Q1 normally; when the LED load is overloaded, the amplified current detection signal is larger than the reference signal, and the comparing unit 14 outputs a high level to charge the charging and discharging unit 15, so that the MOS transistor Q2 is conducted, and the driving signal is pulled down, so that the MOS transistor Q1 is turned off. After the overload protection is activated, MOS transistor Q1 is turned off and no current detection signal is generated. The signal sent to comparison unit 14 via amplification unit 13 is substantially zero, and the output of comparison unit 14 is low. At this time, charge-discharge unit 15 discharges. When the voltage drops to the on-state level of MOS transistor Q2, MOS transistor Q2 is turned off, restoring the drive signal and turning on MOS transistor Q1. The current of the LED load then flows through current detection unit 11 to generate a current detection signal. After amplification, the current detection signal is again compared with the reference signal of comparison unit 14. If the current is greater than the reference voltage, MOS transistor Q2 is turned off again, intermittently lighting up and shutting down the LED load, indicating an abnormality and effectively protecting the LED load and the power supply. When the LED load recovers, the drive signal returns to normal, and the LED lights up normally. Similarly, when a short circuit occurs in the LED load, the drive signal is also pulled low, effectively protecting MOS transistor Q1 from burning out and effectively protecting the driver from short-circuit faults. When the short-circuit fault is resolved, the drive signal returns to normal, and the LED lights up normally.It effectively protects LED lighting products, avoids heat damage caused by overcurrent, and extends the service life of LEDs; effectively protects LED drivers, avoids overheating and damage caused by overload, and extends the service life of LED drivers; effectively protects the driver's MOS tube from damage caused by output short circuit, reducing application risks and failure rates; effectively improves application risks, when overloaded, the LED lighting will light up and shut down at intervals, effectively prompting fault phenomena in the application, facilitating timely debugging and repair of faults.

[0013] like Figure 1 As shown, the circuit further includes a resistor R1, a resistor R2, a resistor R3, and a diode D1. A driving signal is input to one end of the resistor R1, and the other end of the resistor R1 is electrically connected to one end of the resistor R2, the D electrode of the MOS tube Q2, and the anode of the diode D1, respectively. The other end of the resistor R2 is grounded, and the cathode of the diode D1 is electrically connected to the G electrode of the MOS tube Q1 and one end of the resistor R3, respectively. The other end of the resistor R3 is electrically connected to the S electrode of the MOS tube Q1. When the LED load is normal, the driving signal passes through the resistor R1 and the diode D1 to drive the MOS tube Q1 to turn on normally.

[0014] Furthermore, a filtering unit 12 is included. The filtering unit 12 includes a resistor R4 and a capacitor C2. One end of the resistor R4 is electrically connected to the S-pole of the MOS transistor Q1 and the input of the current detection unit 11, respectively. The other end of the resistor R4 is electrically connected to the input of the amplifier unit 13 and one end of the capacitor C2, respectively. The other end of the capacitor C2 is grounded. The current detection signal generated by the current detection unit 11 is filtered by the resistor R4 and the capacitor C2 and then sent to the amplifier unit 13.

[0015] The current detection unit 11 includes a resistor R5, one end of which is electrically connected to the S-pole of the MOS transistor Q1 and one end of the resistor R4, respectively, and the other end of the resistor R5 is grounded. The amplification unit 13 includes an operational amplifier U1, a resistor R7, a resistor R9, and a capacitor C4. The positive input terminal of the operational amplifier U1 is electrically connected to the other end of the resistor R4, the negative input terminal of the operational amplifier U1 is electrically connected to one end of the resistor R7, one end of the resistor R9, and one end of the capacitor C4, the other end of the resistor R9 is grounded, and the other end of the resistor R7 and the other end of the capacitor C4 are electrically connected to the output terminal of the operational amplifier U1 and the input terminal of the comparison unit 14, respectively. The comparison unit 14 includes an operational amplifier U2, a resistor R8, a resistor R10, a capacitor C1, and a capacitor C5. The positive input terminal of the operational amplifier U2 is electrically connected to the output terminal of the amplification unit 13 and one end of the capacitor C1, respectively. The negative input terminal of the operational amplifier U2 is electrically connected to one end of the capacitor C5, one end of the resistor R8, and one end of the resistor R10, respectively. The other end of the resistor R10 and the other end of the capacitor C5 are grounded, respectively. The other end of the resistor R8 is input with a DC voltage VCC. The output terminal of the operational amplifier U2 is electrically connected to the other end of the capacitor C1 and the input terminal of the charge and discharge unit 15, respectively.

[0016] The charge and discharge unit 15 includes a diode D2, a capacitor C3, and a resistor R6. The anode of the diode D2 is electrically connected to the output end of the comparison unit 14, and the cathode of the diode D2 is electrically connected to one end of the capacitor C3, one end of the resistor R6, and the G electrode of the MOS transistor Q2, respectively. The other end of the capacitor C3 and the other end of the resistor R6 are grounded, respectively. When the LED load is overloaded, current flows through resistor R5 to generate a current detection signal. After being filtered by filter unit 12, it is sent to operational amplifier U1. After being amplified by U1, it is sent to operational amplifier U2 for comparison. When the amplified current detection signal is greater than the reference signal, the output of operational amplifier U2 is high. The high level charges capacitor C3 through diode D2. When the voltage gradually rises to the turn-on voltage of MOS transistor Q2, MOS transistor Q2 turns on, causing the input drive signal to be pulled low. MOS transistor Q1 is turned off, shutting off the LED load, and effectively protecting the LED load and LED driver. When the overload protection is activated, no current flows through resistor R5, and the output of operational amplifier U2 is low. At this time, diode D2 is reversely cut off, and the voltage level of capacitor C3 slowly decreases. The time constant is determined by resistor R6 and capacitor C3. When the voltage level of capacitor C3 drops to the turn-on level of MOS transistor Q2, MOS transistor Q2 is turned off, and the drive signal is restored.

[0017] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above preferred embodiments can be freely combined and superimposed.

[0018] The above are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the utility model concept, or directly or indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An LED driver overload protection circuit, characterized in that: include: MOS tube Q1, MOS tube Q2, a current detection unit (11), an amplifying unit (13), a comparing unit (14) and a charging and discharging unit (15); the G pole of the MOS tube Q1 and the D pole of the MOS tube Q2 are respectively electrically connected to the driving signal end of the LED driver; the D pole of the MOS tube Q1 is electrically connected to the LED load; the S pole of the MOS tube Q1 is electrically connected to the input end of the current detection unit (11); the output end of the current detection unit (11) is electrically connected to the input end of the amplifying unit (13); the output end of the amplifying unit (13) is electrically connected to the input end of the comparing unit (14); the output end of the comparing unit (14) is electrically connected to the input end of the charging and discharging unit (15); one output end of the charging and discharging unit (15) is electrically connected to the G pole of the MOS tube Q2; the other output end of the charging and discharging unit (15) and the S pole of the MOS tube Q2 are respectively grounded; The driving signal drives the MOS tube Q1 so that the LED load is normally turned on. The current flows through the current detection unit (11) to generate a current detection signal. The current detection signal is amplified by the amplifying unit (13) and sent to the comparing unit (14) to be compared with the reference signal of the comparing unit (14). When the LED load is normal, the amplified current detection signal is smaller than the reference signal, and the comparing unit (14) outputs a low level, so that the MOS tube Q2 is not turned on, so that the driving signal drives the MOS tube Q1 normally. When the LED load is overloaded, the amplified current detection signal is larger than the reference signal, and the comparing unit (14) outputs a high level to charge the charging and discharging unit (15), so that the MOS tube Q2 is turned on, and the driving signal is pulled down, so that the MOS tube Q1 is turned off.

2. The LED driver overload protection circuit according to claim 1, wherein: The circuit includes a resistor R1, a resistor R2, a resistor R3, and a diode D1. A driving signal is input to one end of the resistor R1, and the other end of the resistor R1 is electrically connected to one end of the resistor R2, the D electrode of the MOS transistor Q2, and the anode of the diode D1. The other end of the resistor R2 is grounded. The cathode of the diode D1 is electrically connected to the G electrode of the MOS transistor Q1 and one end of the resistor R3. The other end of the resistor R3 is electrically connected to the S electrode of the MOS transistor Q1.

3. The LED driver overload protection circuit according to claim 1, wherein: The filter unit (12) includes a resistor R4 and a capacitor C2, one end of the resistor R4 is electrically connected to the S pole of the MOS tube Q1 and the input end of the current detection unit (11), the other end of the resistor R4 is electrically connected to the input of the amplification unit (13) and one end of the capacitor C2, and the other end of the capacitor C2 is grounded.

4. The LED driver overload protection circuit according to claim 3, wherein: The current detection unit (11) comprises a resistor R5, one end of which is electrically connected to the S pole of the MOS tube Q1 and one end of the resistor R4, respectively, and the other end of the resistor R5 is grounded.

5. The LED driver overload protection circuit according to claim 3, wherein: The amplifying unit (13) includes an operational amplifier U1, a resistor R7, a resistor R9 and a capacitor C4, wherein the positive input terminal of the operational amplifier U1 is electrically connected to the other end of the resistor R4, the negative input terminal of the operational amplifier U1 is electrically connected to one end of the resistor R7, one end of the resistor R9 and one end of the capacitor C4, the other end of the resistor R9 is grounded, and the other end of the resistor R7 and the other end of the capacitor C4 are electrically connected to the output terminal of the operational amplifier U1 and the input terminal of the comparing unit (14) respectively.

6. The LED driver overload protection circuit according to claim 1, wherein: The comparison unit (14) includes an operational amplifier U2, a resistor R8, a resistor R10, a capacitor C1, and a capacitor C5. The positive input terminal of the operational amplifier U2 is electrically connected to the output terminal of the amplification unit (13) and one end of the capacitor C1, respectively. The negative input terminal of the operational amplifier U2 is electrically connected to one end of the capacitor C5, one end of the resistor R8, and one end of the resistor R10, respectively. The other end of the resistor R10 and the other end of the capacitor C5 are grounded, respectively. The other end of the resistor R8 inputs a DC voltage VCC, and the output terminal of the operational amplifier U2 is electrically connected to the other end of the capacitor C1 and the input terminal of the charge and discharge unit (15).

7. The LED driver overload protection circuit according to claim 1, wherein: The charge and discharge unit (15) comprises a diode D2, a capacitor C3 and a resistor R6, the anode of the diode D2 is electrically connected to the output end of the comparison unit (14), the cathode of the diode D2 is electrically connected to one end of the capacitor C3, one end of the resistor R6 and the G pole of the MOS tube Q2, respectively, and the other end of the capacitor C3 and the other end of the resistor R6 are grounded respectively.

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