An LED driving power-off detection circuit, an LED lighting device and a control method

Abstract

The present invention discloses an LED driver power-off detection circuit, LED lighting equipment, and control method. The LED driver power-off detection circuit includes: a control module and a power-off detection module; the power-off detection module includes a sampling terminal and a reset signal output terminal; the sampling terminal of the power-off detection module is connected to the power-off detection point of the LED driver power-off detection circuit; the reset signal output terminal is connected to the control module; the power-off detection module is configured to output a reset signal to the control module via the reset signal output terminal when the LED driver power-off detection circuit is determined to be in a power-off state based on the voltage or current detected by the sampling terminal. In the present invention, when the LED driver power-off detection circuit loses power, the control module can be reset in a timely manner, thereby preventing the components in the LED driver power-off detection circuit from being in an unstable working state under low voltage conditions and ensuring that the LED driver power-off detection circuit can operate normally when powered on again.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to an LED drive power-off detection circuit, an LED lighting device, and a control method. Background Art

[0002] LED lighting has the advantages of high brightness, high efficiency and long life and is widely used.

[0003] In order to ensure the power supply of the LED driver circuit in the existing LED driver chip, a capacitor is connected to the power supply pin of the circuit or the power supply pin of the circuit is directly connected to a terminal of a large-capacity capacitor in the circuit. When the circuit is powered off, since a large amount of charge is still stored on the capacitor, it takes a long time for the voltage on the capacitor to drop to the undervoltage lockout state trigger point of the circuit, or the power supply is restored after a period of time if it does not drop to the undervoltage lockout state trigger point of the circuit.

[0004] Undervoltage lockout, also known as low voltage lockout, means that when the output voltage of a regulated power supply drops to a certain limit value (undervoltage lockout point) for some reason, the undervoltage lockout circuit can cut off the power supply and keep it in the cut-off state (i.e., latched). When the power supply voltage rises to a value above the limit value, the circuit can resume normal power supply. This is a protection measure to ensure that the circuit does not malfunction or poor circuit performance due to the operating voltage being too low.

[0005] In this case, after the LED driver circuit loses power, the capacitor still retains a large amount of charge, so the capacitor voltage takes a long time to drop to the undervoltage lockout point of the undervoltage detection module. When the bus loses power, it continues to supply energy to the LED driver circuit, but the actual bus voltage is no longer sufficient to maintain normal operation of the components in the circuit. From the time the bus loses power to the time the undervoltage lockout state is actually entered, it is necessary to wait for the charge on the capacitor to discharge completely. During this period, the LED driver circuit remains in an abnormal operating state due to the low voltage, and the components in the circuit are also in an unstable operating state, causing the internal undervoltage lockout control of the circuit to fail. If the system is powered on again during this period, since the components within the circuit (such as the control module) have not been reset (RESET), the circuit will continue to operate from its current failed state, which can easily cause damage to the entire circuit or malfunction, affecting the normal use of the LED driver circuit. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide an LED driver power-off detection circuit, an LED lighting device, and a control method that overcome the above problems or at least partially solve the above problems.

[0007] In a first aspect, an embodiment of the present invention provides an LED driver power failure detection circuit, comprising: a control module and a power failure detection module; the power failure detection module comprises a sampling terminal and a reset signal output terminal;

[0008] The sampling end of the power-off detection module is connected to the power-off detection point of the LED driving power-off detection circuit; the reset signal output end is connected to the control module;

[0009] The power-off detection module is configured to output a reset signal to the control module through the reset signal output terminal when it is determined that the LED driving power-off detection circuit is in a power-off state according to the voltage or current detected by the sampling terminal.

[0010] In one embodiment, the LED driver power-off detection circuit further includes: a driver module, one end of the driver module is connected to the control module, and the other end is connected to the power tube M1;

[0011] The sampling terminal of the power failure detection module is connected to the drain terminal of the power tube M1.

[0012] In one embodiment, a sampling terminal of the power-off detection module is connected to a power-off detection point on a busbar of the LED driver power-off detection circuit.

[0013] In one embodiment, the power failure detection module includes: a voltage detection circuit and a timer connected to the voltage detection circuit;

[0014] The voltage detection circuit has the sampling terminal and the detection result signal output terminal; the timer is connected via the detection result signal output terminal;

[0015] The timer is provided with the reset signal output terminal;

[0016] The voltage detection circuit is used to determine whether the LED driver power-off detection circuit is powered off according to the voltage detected by the sampling terminal, and output the power-off signal to the timer to trigger the timer to start timing when it is determined that the power is off;

[0017] The timer is configured to output a reset signal through the reset signal output terminal when the timed value reaches a preset time threshold.

[0018] In one embodiment, the power-off detection module further includes: an oscillator, wherein the oscillator is connected to the timer and inputs a clock signal to the timer.

[0019] In one embodiment, the voltage detection circuit is a comparator, one input terminal of the comparator is the sampling terminal, the other input terminal is a reference voltage input terminal, and the output terminal of the comparator is the detection result signal output terminal.

[0020] In one embodiment, the power failure detection module further includes: a resistor R1 and a resistor R2 connected in series;

[0021] The sampling end of the voltage detection circuit is connected between the resistor R1 and the resistor R2 and is connected to the power-off detection point of the LED driving power-off detection circuit through the resistor R1. The resistor R2 is grounded.

[0022] In one embodiment, the voltage detection circuit is specifically used to compare the voltage value detected by the sampling end with the value of a preset reference voltage. If the voltage value is less than the value of the reference voltage, it is determined that the LED drive power-off detection circuit is powered off. The value of the reference voltage V ref satisfy: V p is the peak value of the bus voltage or the drain terminal voltage of the power tube, r1 is the resistance value of the resistor R1, and r2 is the resistance value of the resistor R2.

[0023] In one embodiment, the LED driver power-off detection circuit further includes: a power supply module and an undervoltage lockout module, wherein the power supply module is connected to the bus; one end of the undervoltage lockout module is connected to the power supply module, and the other end is respectively connected to the control module and the power-off detection module;

[0024] The undervoltage lockout module is used to send a reset signal to the power-off detection module and the control module respectively when it is determined that the voltage value output by the power supply module reaches a preset undervoltage lockout point.

[0025] In a second aspect, an embodiment of the present invention provides an LED lighting device, wherein the LED lighting device comprises the aforementioned LED driver power-off detection circuit and an LED lamp connected to the LED driver power-off detection circuit.

[0026] In a third aspect, an embodiment of the present invention provides a method for controlling an LED driver power-off detection circuit, comprising:

[0027] Collect the voltage or current value of the power-off detection point preset by the LED driver power-off detection circuit;

[0028] Determining whether the LED driver power-off detection circuit is in a power-off state based on the collected voltage or current value and a preset reference voltage value or reference current value;

[0029] If the answer is yes, the control module in the LED drive power-off detection circuit is controlled to reset.

[0030] In one embodiment, judging whether the LED driver power-off detection circuit is in a power-off state based on the collected voltage value and a preset reference voltage value specifically includes:

[0031] When the voltage detected by the sampling end is used to determine whether the LED driver power-off detection circuit is powered off and the duration of the power-off reaches a preset duration threshold, the LED driver power-off detection circuit is determined to be in a power-off state; the duration threshold is greater than the period T of the bus voltage after rectification.

[0032] In one embodiment, the determining whether the LED driver power-off detection circuit is powered off according to the voltage detected by the sampling terminal includes:

[0033] The voltage value detected by the sampling end is compared with the preset reference voltage value. If it is less than the reference voltage value, it is determined that the LED drive power-off detection circuit is powered off. The reference voltage value V ref satisfy: V p is the peak value of the bus voltage or the drain terminal voltage of the power tube, r1 is the resistance value of the resistor R1, and r2 is the resistance value of the resistor R2.

[0034] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0035] In an LED driver power-off detection circuit, LED lighting device, and control method provided by an embodiment of the present invention, the LED driver power-off detection circuit includes a power-off detection module. A sampling terminal of the power-off detection module is connected to a preset power-off detection point in the LED driver power-off detection circuit, and a reset signal output terminal of the power-off detection module is connected to a control module. When the LED driver power-off detection circuit is determined to be in a power-off state based on the voltage or current detected by the sampling terminal, a reset signal is sent to the control module. This allows the control module to be reset promptly under abnormal working conditions when the LED driver power-off detection circuit loses power and before entering an undervoltage lockout state, thereby ensuring that the LED driver power-off detection circuit can operate normally when powered on again. This avoids the problem of components in the LED driver power-off detection circuit being in an unstable operating state due to the presence of a capacitor in the circuit continuing to supply energy to the LED driver power-off detection circuit while the actual bus voltage is insufficient to maintain normal operation of the LED driver power-off detection circuit. When the bus is powered on again, the LED driver power-off detection circuit may malfunction or be damaged.

[0036] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0037] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0039] Figure 1A and Figure 1B This is a diagram showing the structure and voltage waveform of an existing LED drive circuit;

[0040] Figure 2 This is a schematic diagram of the structure of the LED driver power failure detection circuit provided by an embodiment of the present invention;

[0041] Figure 3 This is a second structural diagram of the LED driver power-off detection circuit provided by an embodiment of the present invention;

[0042] Figure 4 The embodiment of the present invention provides a working process of the power failure detection module when the LED driver power failure detection circuit is powered off;

[0043] Figure 5 A schematic diagram of the internal structure of a power outage detection module provided in an embodiment of the present invention;

[0044] Figure 6 An exemplary diagram of a voltage detection circuit provided by an embodiment of the present invention;

[0045] Figure 7A and 7B The structure and voltage waveform of the LED driver power-off detection circuit provided in the first embodiment of the present invention;

[0046] Figure 8 This is a flowchart of the power-off detection module in the LED driver power-off detection circuit provided in the first embodiment of the present invention;

[0047] Figure 9A and 9B The structure and voltage waveform of the LED driver power-off detection circuit provided in the second embodiment of the present invention;

[0048] Figure 10A and 10B The structure and voltage waveform of the LED driver power-off detection circuit provided in the third embodiment of the present invention;

[0049] Figure 11A and 11B The structure and voltage waveform of the LED driver power-off detection circuit provided in the fourth embodiment of the present invention;

[0050] Figure 12 A flow chart of a control method for an LED driver power-off detection circuit according to an embodiment of the present invention;

[0051] Description of reference numerals:

[0052] 1 LED driver power-off detection circuit;

[0053] 11 Control Module

[0054] 12 Power failure detection module

[0055] 13 Driver Module

[0056] 14 Power supply module

[0057] 15 Undervoltage lockout module

[0058] 121 Voltage Detection Circuit

[0059] 122 Timer

[0060] 123 oscillator. DETAILED DESCRIPTION

[0061] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0062] Before describing the LED driver power failure detection circuit, LED lighting device, and control method provided by the embodiments of the present invention, the structure and principle of an existing LED driver circuit are briefly described. Figure 1A and Figure 1B As shown in the dotted box, in the LED drive circuit, the power supply module obtains power from the bus, the power supply module supplies power to the control module, and the control module CS The sampling current feedback is used to control the power tube M1 through the drive module. The principle of its undervoltage lockout mechanism is as follows: When the bus voltage V M When the power is off and the undervoltage detection module determines that the undervoltage lockout point has been reached, it sends an RSET signal to reset the control module and enter the undervoltage lockout state.

[0063] This type of circuit has the following problems: capacitor C1 is connected between the bus and the ground. After the LED driver circuit is powered off, since there is still a large amount of charge on capacitor C1, it takes a long time for the voltage of capacitor C1 to drop to the undervoltage lockout point of the undervoltage detection module. When the bus is powered off, it will continue to supply energy to the LED driver circuit, but the actual bus voltage is no longer sufficient to maintain the normal operation of the components in the circuit. From the beginning of the bus power loss to the actual entry into the undervoltage lockout state, it is necessary to wait for the charge on capacitor C1 to be discharged. In the case that the bus has resumed normal power supply before reaching the undervoltage lockout point, for example, refer to Figure 1B In the time period t1 to t2, the bus starts to lose power at t1, and the bus resumes power supply at t2 before reaching the undervoltage lockout point. During this time period, since the components inside the LED driver circuit have not been reset (RSET is high, that is, invalid level), they will continue to work from the current failed state, which may easily cause failure or damage to the entire circuit and affect the normal use of the LED driver circuit.

[0064] To address the problem that, after a power outage (or power failure) in an existing LED driver circuit, the capacitor in the circuit continues to supply power to the entire LED driver circuit to maintain operation, but the voltage at this time is an unstable low voltage, causing the entire LED driver circuit to operate unstably when power is restored, embodiments of the present invention provide an LED driver circuit capable of power-off detection (hereinafter referred to as an LED driver power-off detection circuit), an LED lighting device, and a control method for the LED driver power-off detection circuit.

[0065] The LED driver power-off detection circuit provided by the embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0066] An embodiment of the present invention provides an LED driver power failure detection circuit, comprising: a control module and a power failure detection module; wherein the power failure detection module comprises a sampling terminal and a reset signal output terminal;

[0067] The sampling end of the power-off detection module is connected to the power-off detection point of the LED driver power-off detection circuit; the reset signal output end is connected to the control module;

[0068] The power-off detection module is used to output a reset signal to the control module through the reset signal output terminal when it is determined that the LED driving power-off detection circuit is in a power-off state according to the voltage or current detected by the sampling terminal.

[0069] In the LED driver power-off detection circuit provided by an embodiment of the present invention, the power-off detection module can collect the voltage or current of the LED driver power-off detection circuit according to a preset power-off sampling point in the LED driver power-off detection circuit. When the LED driver power-off detection circuit is determined to be in a power-off state based on the voltage or current detected at the sampling end, the module sends a reset signal to the control module. When the LED driver power-off detection circuit loses power and enters an undervoltage lockout state, the control module can be reset in a timely manner under an abnormal working state, thereby ensuring that the LED driver power-off detection circuit can operate normally when powered on again. This avoids the problem of components in the LED driver power-off detection circuit being in an unstable working state due to the presence of a capacitor in the circuit continuing to supply energy to the LED driver power-off detection circuit while the actual bus voltage is insufficient to maintain the normal operation of the LED driver power-off detection circuit. When the bus is powered on again, the LED driver power-off detection circuit may malfunction or be damaged.

[0070] For the LED driver power-off detection circuit, the voltage or current at each position point in the LED driver power-off detection circuit will decay after power is off. Taking the voltage power-off detection point as an example, there may be multiple ways to facilitate data collection and calculation. For example, the power-off detection point can be located at any point on the bus, or the power-off detection point can be the drain end of the power tube M1 connected to the driver module.

[0071] Reference Figure 2 The example shown in Figure 2 The LED driver power failure detection circuit 1 shown ( Figure 2 In the circuit shown in the dotted box), in addition to the control module 11 and the power failure detection module 12, the LED driver power failure detection circuit also includes: a driver module 13; one end of the driver module 13 is connected to the control module 11, and the other end is connected to the power tube M1;

[0072] The sampling terminal of the power failure detection module 12 is connected to the drain terminal of the power tube M1 .

[0073] Reference Figure 3 The example shown in Figure 3 In the LED driver power failure detection circuit 1 shown in FIG. Figure 3 In the circuit shown in the dotted box), the sampling end of the power-off detection module 12 is connected to the power-off detection point on the busbar of the LED driver power-off detection circuit.

[0074] Sampling the voltage from the drain end of the power tube M1 is chosen because the voltage value detected from the power tube M1 is smaller than the voltage value detected from the bus. Therefore, when sampling the voltage from the drain end of the power tube M1, the waveform at the drain end is significantly different between the power-off and power-on states. This method does not require an overly sophisticated detection circuit and is easy to judge.

[0075] In the above embodiment, the power failure detection module 12 compares the sampled voltage with a preset reference voltage to determine whether the current state is a power failure. The preset reference voltage value can be predetermined based on the voltage at the power failure detection point under normal voltage conditions.

[0076] The advantage of bus voltage sampling is that when power outage begins, the bus responds to the power outage most promptly. Other locations within the LED driver power-off detection circuit react with lag, so bus sampling can determine the arrival of power outage more promptly.

[0077] At the same time, for the sampling position, sampling can also be done from the busbar and the sampling point at the same time, combining the advantages of both.

[0078] When both the bus sampling and the sampling point sampling enter the power-off state, it is determined that the system enters the power-off state.

[0079] The working process of the power failure detection module 12 is as follows: Figure 4 As shown, the following steps are included:

[0080] S41, obtaining a sampled voltage or current;

[0081] S42, judging whether the LED driver power-off detection circuit has entered a power-off state based on the acquired voltage or current;

[0082] S43: If the LED driver power-off detection circuit enters a power-off state, reset the control module in the LED driver power-off detection circuit.

[0083] In one embodiment, referring to Figure 5 As shown, the power failure detection module 12 includes: a voltage detection circuit 121 and a timer 122 connected to the voltage detection circuit 121;

[0084] The voltage detection circuit 121 has the sampling terminal and the detection result signal output terminal; the detection result signal output terminal is connected to the timer 122;

[0085] The timer 122 has a reset signal output terminal;

[0086] The voltage detection circuit 121 is used to determine whether the LED driver power-off detection circuit is powered off (not necessarily in the power-off state at this time) based on the voltage detected by the sampling terminal, and output a power-off signal to the timer 122 to trigger the timer 122 to count when the power is off.

[0087] The timer 122 is configured to output a reset signal through a reset signal output terminal when the timed value reaches a preset time threshold.

[0088] The above-mentioned preset duration threshold is greater than or equal to the period T of the bus voltage after the rectifier bridge in the LED driver power-off detection circuit. The reason for this setting is that the bus voltage changes periodically, and its waveform is a half-cycle sine wave, which gradually decays after the peak. Therefore, even in a normal state (no power failure), there will be situations where the value is lower than the reference voltage. To avoid misjudgment, in the embodiment of the present invention, it is necessary to determine that when the sampled voltage is compared with the preset reference voltage value to determine the power failure, it is not necessarily that the power has actually entered the off state. A reasonable time threshold must be maintained before it can be finally determined that the power has entered the off state.

[0089] Reference Figure 5 As shown, the power-off detection module 12 further includes an oscillator (OSC) 123 . The oscillator 123 is connected to the timer 122 and inputs a clock signal to the timer 122 .

[0090] Of course, the timer of the embodiment of the present invention is not limited to the above specific implementation manner, and any circuit that can realize the timing function can be selected.

[0091] In one embodiment, see Figure 6 As shown, the voltage detection circuit 121 is a comparator, which has two input terminals, one of which is a sampling terminal (for example, V DET signal), the other input terminal is the reference voltage input terminal (V REF ), the output end of the comparator is the detection result signal output end (EN signal).

[0092] The detection result signal EN includes a signal in which the sampled voltage is lower than the reference voltage input terminal, or a signal in which the sampled voltage is higher than the reference voltage.

[0093] In one embodiment, referring to Figure 5 As shown, the power failure detection module 12 further includes: a resistor R1 and a resistor R2 connected in series; wherein:

[0094] The sampling end of the voltage detection circuit 121 is connected between the resistor R1 and the resistor R2 and is connected to the power-off detection point of the LED driving power-off detection circuit via the resistor R1 . The resistor R2 is grounded.

[0095] In an embodiment of the present invention, since the bus voltage is relatively large, if it differs greatly from the operating voltage of the voltage detection circuit 121, it is necessary to divide the voltage through resistors R1 and R2 to obtain a voltage value suitable for use by the voltage detection circuit 121, and then pass it to the voltage detection circuit 121 so that the voltage detection circuit 121 can compare it with the reference voltage.

[0096] In one embodiment, the voltage detection circuit 121 is specifically used to compare the voltage value detected by the sampling end with the preset reference voltage value. When the voltage value detected by the sampling end is less than the preset reference voltage value, it is determined that the LED driver power-off detection circuit is powered off (not necessarily in the power-off state). The reference voltage value V ref satisfy: V p is the peak value of the bus voltage or the drain terminal voltage of the power tube M1, r1 is the resistance value of the resistor R1, and r2 is the resistance value of the resistor R2.

[0097] In one embodiment, referring to Figure 2 or Figure 3 As shown, the above-mentioned LED driver power-off detection circuit further includes: a power supply module 14 and an undervoltage lockout module 15, the power supply module 14 is connected to the bus; one end of the undervoltage lockout module 15 is connected to the power supply module 15, and the other end is respectively connected to the control module 11 and the power-off detection module 12;

[0098] The undervoltage lockout module 15 is configured to send a reset signal (also referred to as a reset signal) to the power failure detection module 12 and the control module 11 respectively when determining that the voltage value output by the power supply module 14 reaches a preset undervoltage lockout point.

[0099] In the LED driver power-off detection circuit, the undervoltage lockout module 15 determines whether the entire LED driver power-off detection circuit enters the undervoltage lockout state based on the operating voltage of the power supply module 14, rather than based on the bus voltage of the LED driver power-off detection circuit. The two voltage values are not equal due to the presence of the energy storage capacitor C1. When the bus voltage decreases, the energy storage capacitor C1 can stabilize the voltage to ensure the normal operating voltage of the power supply module. However, this normal state is an unstable state and can only be achieved by periodically charging the energy storage capacitor C1 with the help of the bus voltage. When the bus power is cut off, the next cycle cannot continue to charge, and therefore cannot be sustained. In this case, the components in the LED driver power-off detection circuit are in an unstable operating state, and when the power is turned on again, circuit failure or abnormal operation is likely to occur. In order to solve this problem, in the embodiment of the present invention, a power-off detection module 12 is added to the LED driver power-off detection circuit. If the LED driver power-off detection circuit loses power, the power-off detection module 12 can determine that the LED driver power-off detection circuit has entered a power-off state before the undervoltage lockout module 15 in the LED driver power-off detection circuit determines that the voltage of the control module 11 has not reached the undervoltage lockout point, thereby sending a reset signal to the control module 11 in time to reset the control module 11 until the LED driver power-off detection circuit is restored to power. Assuming that the power is restored, When the voltage value of the power supply module 14 does not reach the preset undervoltage lockout point, the undervoltage lockout module does not work. In another case, assuming that the voltage of the power supply module 14 in the LED driver power-off detection circuit continues to drop until the undervoltage lockout module 15 determines that it has reached the undervoltage lockout point, the undervoltage lockout module 15 starts to activate the undervoltage lockout protection measure. At this time, a reset signal will be sent to the control module 11 and the power-off detection module 12 at the same time. Under the control of this signal, both the control module 11 and the power-off detection module 12 cannot work normally until the LED driver power-off detection circuit is powered on again.

[0100] It should be noted that the embodiments of the present invention Figures 2 to 6 The scheme shown is an example of power failure detection using sampling voltage. The implementation principle of the scheme using current as an example is similar and will not be repeated here.

[0101] In order to better illustrate the structure and working principle of the LED driver power-off detection circuit provided by the embodiments of the present invention, several specific embodiments are described in detail below.

[0102] Example 1:

[0103] The specific implementation scheme of this embodiment is described in detail. Figure 7A As shown, the LED driver power-off detection circuit obtains energy from the busbar through the power supply module. The power supply module supplies power to the control module. The control module samples the current based on the feedback Ics and controls the power transistor M1 through the driver module. One end of capacitor C1 is connected to the busbar, and the other end is grounded.

[0104] The sampling end of the power failure detection module is connected to the bus, that is, the resistors R1 and R2 in the power failure detection module are connected in series to the bus V M It is used to sample the bus voltage and obtain the voltage signal V related to the bus voltage. DET ; The voltage detection circuit converts the voltage signal V DET The value of the preset reference voltage V REF For comparison, when V DET The voltage value is greater than V REF When the voltage is high, the detection result signal output by the voltage detection circuit, i.e., the EN signal, is low. DET Voltage Ratio V REF When the voltage is low, the detection result signal EN output by the voltage detection circuit is high. In this embodiment, it is effective when EN is high; (Of course, the output signal can also be inverted, that is, when V DET Voltage Ratio V REF When the voltage is high, the output EN of the voltage detection circuit is high. DET Voltage Ratio V REF When the voltage is low, the output EN of the voltage detection circuit is low, and EN is valid when it is low).

[0105] Where V REF *(r1+r2) / r2 is less than or equal to the bus voltage V M Peak V p Wherein, r1 is the resistance value of resistor R1, and r2 is the resistance value of resistor R2.

[0106] The OSC module is used to provide a clock (CLK) signal to the timing module. When EN is high, the timer is enabled and starts timing, and compares it with an internally set time threshold Tth, where the value of Tth is greater than or equal to one cycle T of the bus after the rectifier bridge. In this embodiment, Tth is set to 2T to improve the reliability of power-off state detection and prevent false triggering. When the timer duration is greater than Tth (2T), the LED driver power-off detection circuit is determined to be in the power-off state. The timing module (Countor module) in the power-off detection module sends a valid RSET1 signal to the control module, causing the control module to enter the reset state until it detects that the LED driver power-off detection circuit is powered on again, thereby ensuring that the LED driver power-off detection circuit can operate normally when powered on again.

[0107] Reference Figure 7B As shown, V AC is the input voltage before rectification, and the corresponding period of the bus voltage waveform after rectification is T. The LED driver power-off detection circuit loses power at time t1 (the voltage waveform is a dotted line thereafter), and power is restored at time t2.

[0108] Between time t1 and time t2, the EN signal is at a valid level (low level) and the duration exceeds the preset threshold 2T, so the power failure detection module triggers a valid RSET1 signal (low level) to the control module.

[0109] Between time t1 and time t2, the voltage detected by the undervoltage lockout module (the operating voltage of the power supply module) never drops below the preset undervoltage lockout voltage point, so the undervoltage lockout module continuously outputs a high level.

[0110] The working process of the power failure detection module refers to Figure 8 As shown, the power failure detection module detects the bus voltage V DET Sampling is performed to obtain bus voltage information. Then V DET With V REF Compare, if V DET Less than V REF , the timer starts timing and determines whether the timing time reaches the threshold time T th , if it is reached, the reset signal RSET1 is output.

[0111] Example 2:

[0112] Reference Figure 9A As shown, the example of the LED driver power failure detection circuit provided in the second embodiment is similar to that in the first embodiment, except that the sampling end of the power failure detection module is connected to the drain of the power tube M1, and the drain voltage V is collected. DRN The other structures and working principles are similar to those of the first embodiment and will not be described in detail here.

[0113] Figure 9B 1 is the corresponding voltage waveform diagram, wherein the LED driver power failure detection circuit loses power at time t1 (thereafter the voltage waveform is a dotted line), and power is restored at time t2. The working principles shown in each waveform diagram are similar to those in Example 1 and will not be repeated here.

[0114] Example 3:

[0115] Reference Figure 10A As shown, the example of the LED driver power-off detection circuit provided in the third embodiment is similar to that in the first embodiment, except that the capacitor C1 is connected in parallel across the LED load.

[0116] Its voltage waveform (i.e. Figure 10B) and the working principle and process are similar to those of embodiments 1 to 2 and will not be described in detail here.

[0117] Example 4:

[0118] Reference Figure 11A As shown, the example of the LED driver power-off detection circuit provided in the third embodiment is similar to that in the second embodiment, except that the capacitor C1 is connected in parallel across the LED load.

[0119] Its voltage waveform (i.e. Figure 11B ) and the working principle and process are similar to those of embodiments 1 to 3 and will not be described in detail here.

[0120] The LED driver power-off detection circuit provided in the aforementioned embodiment can be applied to various LED loads, including but not limited to LED lamps, etc., and the embodiment of the present invention does not limit this.

[0121] An embodiment of the present invention further provides an LED lighting device, which includes the LED driver power-off detection circuit provided in the above embodiment and an LED lamp connected to the LED driver power-off detection circuit.

[0122] Based on the same inventive concept, an embodiment of the present invention further provides a control method for an LED driver power-off detection circuit. Since the principle of this method is similar to that of the aforementioned LED driver power-off detection circuit and LED lighting device, the implementation of this method can refer to the implementation of the aforementioned LED driver power-off detection circuit, and the repeated parts will not be repeated.

[0123] The embodiment also provides a control method for an LED driver power-off detection circuit, referring to Figure 12 As shown, the following steps are included:

[0124] S11, collecting the voltage or current value of the power-off detection point preset by the LED driver power-off detection circuit;

[0125] S12, judging whether the LED driver power-off detection circuit is in a power-off state based on the collected voltage or current value and a preset reference voltage value or reference current value; if the judgment result is yes, turning to step S13;

[0126] S13, controlling the control module in the LED driver power-off detection circuit to reset.

[0127] Optionally, in the above step S12, judging whether the LED driver power-off detection circuit is in a power-off state based on the collected voltage value and a preset reference voltage value can be achieved in the following manner:

[0128] When the voltage detected by the sampling end is used to determine whether the LED driver power-off detection circuit is powered off and the duration of the power-off reaches a preset duration threshold, the LED driver power-off detection circuit is determined to be in a power-off state; the duration threshold is greater than the period T of the bus voltage after rectification.

[0129] Optionally, the step of determining whether the LED driver power-off detection circuit is powered off based on the voltage detected by the sampling terminal can be implemented by the following steps:

[0130] The voltage value detected by the sampling end is compared with the preset reference voltage value. If it is less than the reference voltage value, it is determined that the LED drive power-off detection circuit is powered off. The reference voltage value V ref satisfy: V p is the peak value of the bus voltage or the drain terminal voltage of the power tube, r1 is the resistance value of the resistor R1, and r2 is the resistance value of the resistor R2.

[0131] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0132] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0133] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0134] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0135] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. An LED driver power failure detection circuit (1), comprising: A control module (11) and a power-off detection module (12); the power-off detection module (12) includes a sampling terminal and a reset signal output terminal; The sampling end of the power-off detection module (12) is connected to the power-off detection point of the LED driving power-off detection circuit; the reset signal output end is connected to the control module; The power-off detection module (12) is used to output a reset signal to the control module through the reset signal output terminal when it is determined that the LED driving power-off detection circuit is in a power-off state according to the voltage or current detected by the sampling terminal; The power failure detection module (12) comprises: a voltage detection circuit (121), a timer (122) connected to the voltage detection circuit (121), and a resistor R1 and a resistor R2 connected in series; The voltage detection circuit (121) has the sampling terminal and the detection result signal output terminal; the detection result signal output terminal is connected to the timer (122); The timer (122) has the reset signal output terminal; The voltage detection circuit (121) is used to determine whether the LED driving power-off detection circuit is powered off based on the voltage detected by the sampling end, and output the power-off signal to the timer (122) to trigger the timer (122) to count when the power is off. The timer (122) is used to determine that the LED driving power-off detection circuit is in a power-off state when the timing reaches a preset time threshold, and output a reset signal through the reset signal output terminal; The sampling end of the voltage detection circuit (121) is connected between the resistor R1 and the resistor R2, and is connected to the power-off detection point of the LED driving power-off detection circuit via the resistor R1, and the resistor R2 is grounded; The voltage detection circuit (121) is specifically used to compare the voltage value detected by the sampling end with the value of a preset reference voltage. If the voltage value is less than the reference voltage value, it is determined that the LED drive power-off detection circuit is powered off. The reference voltage value V ref satisfy: V p is the peak value of the bus voltage or the drain terminal voltage of the power tube, r1 is the resistance value of the resistor R1, and r2 is the resistance value of the resistor R2; The LED drive power-off detection circuit further comprises: a power supply module (14) and an undervoltage lockout module (15), wherein the power supply module (14) is connected to a bus bar; one end of the undervoltage lockout module (15) is connected to the power supply module (14), and the other end is respectively connected to the control module and the power-off detection module (12); The undervoltage lockout module (15) is used to send a reset signal to the power failure detection module (12) and the control module respectively when it is determined that the voltage value output by the power supply module (14) reaches a preset undervoltage lockout point; The undervoltage lockout module (15) is specifically used to judge that before the voltage of the control module (11) does not reach the undervoltage lockout point, the power-off detection module (12) judges that the LED driver power-off detection circuit enters a power-off state, thereby promptly sending a reset signal to the control module (11) to reset the control module (11) until the LED driver power-off detection circuit resumes power supply; when power supply is resumed, if the voltage value of the power supply module (14) does not reach the preset undervoltage lockout point, the undervoltage lockout module (15) does not work; when it is judged that the voltage of the power supply module (14) continues to decrease until it reaches the undervoltage lockout point, the undervoltage lockout protection measure is started, and a reset signal is sent to the control module (11) and the power-off detection module (12) at the same time, so that the control module (11) and the power-off detection module (12) cannot work normally until the LED driver power-off detection circuit resumes power supply again.

2. The circuit according to claim 1, wherein The LED drive power-off detection circuit further comprises: a drive module (13), one end of the drive module (13) being connected to the control module and the other end being connected to the power tube M1; The sampling end of the power failure detection module (12) is connected to the drain end of the power tube M1.

3. The circuit according to claim 1, wherein The sampling end of the power-off detection module (12) is connected to a power-off detection point on the busbar of the LED drive power-off detection circuit.

4. The circuit according to claim 1, wherein The power failure detection module (12) further includes an oscillator (123), wherein the oscillator (123) is connected to the timer (122) and inputs a clock signal to the timer (122).

5. The circuit according to claim 1, wherein The voltage detection circuit (121) is a comparator, one input end of the comparator is the sampling end, the other input end is a reference voltage input end, and the output end of the comparator is the detection result signal output end.

6. An LED lighting device, characterized in that: The LED lighting device comprises the LED driving power-off detection circuit according to any one of claims 1 to 5 and an LED lamp connected to the LED driving power-off detection circuit.

7. A control method for an LED driver power-off detection circuit, characterized in that: include: collecting a voltage or current value of a power-off detection point preset by the LED driver power-off detection circuit according to any one of claims 1 to 5; Determining whether the LED driver power-off detection circuit is in a power-off state based on the collected voltage or current value and a preset reference voltage value or reference current value; If the answer is yes, the control module in the LED drive power-off detection circuit is controlled to reset.

8. The method according to claim 7, wherein According to the collected voltage value and the preset reference voltage value, determining whether the LED driver power-off detection circuit is in a power-off state specifically includes: If the voltage value detected by the sampling end of the power-off detection module in the LED driver power-off detection circuit is less than the preset reference voltage value, it is determined that the LED driver power-off detection circuit is powered off, and when the power-off duration reaches a preset duration threshold, it is determined that the LED driver power-off detection circuit is in a power-off state; the duration threshold is greater than the period T of the bus voltage after rectification.

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