CN114080080A - LED drive power-off detection circuit, LED lighting equipment and control method - Google Patents

LED drive power-off detection circuit, LED lighting equipment and control method Download PDF

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CN114080080A
CN114080080A CN202010805491.2A CN202010805491A CN114080080A CN 114080080 A CN114080080 A CN 114080080A CN 202010805491 A CN202010805491 A CN 202010805491A CN 114080080 A CN114080080 A CN 114080080A
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power
voltage
detection circuit
module
detection
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张攀
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Meixinsheng Technology Beijing Co ltd
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Meixinsheng Technology Beijing Co ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

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Abstract

The invention discloses an LED drive power-off detection circuit, LED lighting equipment and a control method. LED drive outage detection circuitry includes: the power failure detection module is used for detecting power failure; the power failure detection module comprises a sampling end and a reset signal output end; the sampling end of the power-off detection module is connected with a power-off detection point of the LED drive power-off detection circuit; the reset signal output end is connected with the control module; the power-off detection module is used for outputting a reset signal to the control module through the reset signal output end when the LED driving power-off detection circuit is determined to be in a power-off state according to the voltage or the current detected by the sampling end. According to the invention, when the LED drive power-off detection circuit is powered off, the control module can be timely reset, so that the situation that devices in the LED drive power-off detection circuit are in an unstable working state in a low-voltage state is avoided, and the LED drive power-off detection circuit can work normally when being powered on again is ensured.

Description

LED drive power-off detection circuit, LED lighting equipment and control method
Technical Field
The invention relates to the technical field of integrated circuits, in particular to an LED drive power-off detection circuit, LED lighting equipment and a control method.
Background
LED lighting is widely used for its advantages of high brightness, high efficiency, long life, etc.
LED drive circuit among the current LED driver chip is in order to guarantee LED drive circuit's power supply, can connect a electric capacity or directly with this circuit's power supply foot in the circuit on a terminal that has large capacity electric capacity, after this circuit outage, because still there is a large amount of charges on the electric capacity, voltage on the electric capacity needs very long time just can descend to this circuit's undervoltage latch state trigger point, perhaps resume the power supply after not falling to circuit's undervoltage latch state trigger point a period.
Under-voltage latch, also called low-voltage latch, means that when the output voltage of the regulated power supply drops to a certain limit value (under-voltage latch point) due to some reason, the under-voltage latch circuit can cut off the power supply and keep the cut-off state (i.e. latch), and when the power supply voltage rises to a certain value above the limit value, the circuit can recover normal power supply, which is a protection measure for preventing the circuit from abnormal operation or poor circuit performance due to over-low working voltage.
Under the condition, after the LED driving circuit is powered off, because a large amount of charges are stored in the capacitor, the voltage of the capacitor can be lowered to the undervoltage latch point of the undervoltage detection module only after a long time, when the bus is powered off, the energy can be continuously supplied to the LED driving circuit, but the real bus voltage is not enough to maintain the normal work of each component in the circuit, and the charge on the capacitor needs to be waited for finishing the discharge from the power failure of the bus to the real entering of the undervoltage latch state. During the period, the LED driving circuit is always in an abnormal working state due to low voltage, devices in the circuit are also in an unstable working state, so that low-voltage latch control in the circuit is failed, and during the period, if the system is powered on again, the devices in the circuit (such as a control module) are not subjected to RESET operation (RESET); the circuit can continue to work from the current failure state, easily causes the damage of whole circuit or does not work normally scheduling problem, influences the normal use of LED drive circuit.
Disclosure of Invention
In view of the above problems, the present invention has been made to provide an LED driving power-off detection circuit, an LED lighting device, and a control method that overcome or at least partially solve the above problems.
In a first aspect, an embodiment of the present invention provides an LED driving power-off detection circuit, including: the power failure detection module is used for detecting power failure; the power failure detection module comprises a sampling end and a reset signal output end;
the sampling end of the power-off detection module is connected with a power-off detection point of the LED drive power-off detection circuit; the reset signal output end is connected with the control module;
the power-off detection module is used for outputting a reset signal to the control module through the reset signal output end when the LED driving power-off detection circuit is determined to be in a power-off state according to the voltage or the current detected by the sampling end.
In one embodiment, the LED driving power-off detection circuit further includes: one end of the driving module is connected with the control module, and the other end of the driving module is connected with a power tube M1;
the sampling end of the power-off detection module is connected with the drain end of the power tube M1.
In one embodiment, the sampling end of the power-off detection module is connected to a power-off detection point on the bus of the LED driving power-off detection circuit.
In one embodiment, the power outage detection module includes: the voltage detection circuit and the timer are connected with the voltage detection circuit;
the voltage detection circuit is provided with the sampling end and a detection result signal output end; the signal output end of the detection result is connected with a timer;
the timer is provided with the reset signal output end;
the voltage detection circuit is used for judging whether the LED driving power-off detection circuit is powered off or not according to the voltage detected by the sampling end, and outputting the power-off signal to the timer to trigger the timer to time when the power-off is judged;
the timer is used for outputting a reset signal through the reset signal output end when the timing reaches a preset duration threshold.
In one embodiment, the power outage detection module further includes: and the oscillator is connected with the timer and inputs a clock signal to the timer.
In one embodiment, the voltage detection circuit is a comparator, one input terminal of the comparator is the sampling terminal, the other input terminal of the comparator is a reference voltage input terminal, and the output terminal of the comparator is the detection result signal output terminal.
In one embodiment, the power outage detection module further includes: a resistor R1 and a resistor R2 connected in series;
the sampling end of the voltage detection circuit is connected between the resistor R1 and the resistor R2, and is connected with a power-off detection point of the LED drive power-off detection circuit through the resistor R1, and the resistor R2 is grounded.
In an embodiment, the voltage detection circuit is specifically configured to compare a value of a voltage detected by the sampling terminal with a preset reference voltage value, and if the value of the voltage is smaller than the reference voltage value, determine that the LED driving power-off detection circuit is powered off, where the reference voltage value V isrefSatisfies the following conditions:
Figure BDA0002628969770000031
Vpis the peak value of the bus voltage or the voltage at the drain end of the power tube, r1Is the resistance value of the resistor R1, R2Is the resistance value of the resistor R2.
In one embodiment, the LED driving power-off detection circuit further includes: the power supply module is connected with the bus; one end of the under-voltage latch module is connected with the power supply module, and the other end of the under-voltage latch module is respectively connected with the control module and the power failure detection module;
and the under-voltage latch module is used for respectively sending reset signals to the power failure detection module and the control module when judging that the voltage value output by the power supply module reaches a preset under-voltage latch point.
In a second aspect, the embodiment of the present invention provides an LED lighting device, which includes the LED driving power-off detection circuit and an LED lamp connected to the LED driving power-off detection circuit.
In a third aspect, an embodiment of the present invention provides a method for controlling an LED driving power-off detection circuit, including:
collecting the voltage or current value of a power-off detection point preset by an LED drive power-off detection circuit;
judging whether the LED driving power-off detection circuit is in a power-off state or not according to the acquired voltage or current value and a preset reference voltage value or reference current value;
if the LED driving power-off detection circuit is judged to be yes, the control module in the LED driving power-off detection circuit is controlled to reset.
In one embodiment, the determining whether the LED driving power-off detection circuit is in a power-off state according to the collected voltage value and a preset reference voltage value specifically includes:
judging whether the LED driving power-off detection circuit is powered off or not according to the voltage detected by the sampling end, and determining that the LED driving power-off detection circuit is in a power-off state when the power-off duration time reaches a preset time threshold; the time length threshold value is larger than the period T of the rectified bus voltage.
In one embodiment, the determining whether the LED driving power-off detection circuit is powered off according to the voltage detected by the sampling terminal includes:
comparing the voltage value detected by the sampling end with a preset reference voltage value, if the voltage value is smaller than the reference voltage value, judging that the LED drive power-off detection circuit is powered off, and judging that the reference voltage value V is the voltage VrefSatisfies the following conditions:
Figure BDA0002628969770000041
Vpis the peak value of the bus voltage or the voltage at the drain end of the power tube, r1Is the resistance value of the resistor R1, R2Is the resistance value of the resistor R2.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
in the LED driving power-off detection circuit, the LED lighting equipment and the control method provided by the embodiment of the invention, the LED driving power-off detection circuit comprises a power-off detection module, a sampling end of the power-off detection module is connected with a preset power-off detection point in the LED driving power-off detection circuit, a reset signal output end of the power-off detection module is connected with a control module, when the LED driving power-off detection circuit is determined to be in a power-off state according to the voltage or current detected by the sampling end, the control module can be timely reset in an abnormal working state before entering an undervoltage latching state when the LED driving power-off detection circuit is in a power-off state by sending a reset signal to the control module, the LED driving power-off detection circuit can be ensured to normally work when the LED driving power-off detection circuit is powered on again, and the situation that the energy is continuously supplied to the LED driving power-off detection circuit due to the capacitor in the circuit and the actual bus voltage is not enough to maintain the normal work of the LED driving power-off detection circuit is avoided The LED drive power-off detection circuit is in an unstable working state, and when the bus is electrified again, the problem that the LED drive power-off detection circuit is in failure or damaged is easily caused.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1A and 1B are diagrams illustrating a structure and voltage waveforms of a conventional LED driving circuit;
fig. 2 is a schematic structural diagram of an LED driving power-off detection circuit according to an embodiment of the present invention;
fig. 3 is a second schematic structural diagram of an LED driving power-off detection circuit according to an embodiment of the present invention;
FIG. 4 is a flowchart illustrating the operation of the power-off detection module when the LED driving power-off detection circuit is powered off according to the embodiment of the present invention;
fig. 5 is a schematic diagram of an internal structure of the power outage detection module according to the embodiment of the present invention;
FIG. 6 is a diagram of an exemplary voltage detection circuit according to an embodiment of the present invention;
fig. 7A and 7B are diagrams of the structure and voltage waveforms of an LED driving power-off detection circuit according to an embodiment of the present invention;
fig. 8 is a flowchart illustrating a power failure detection module in an LED driving power failure detection circuit according to an embodiment of the present invention;
fig. 9A and 9B are diagrams of the structure and voltage waveforms of an LED driving power-off detection circuit according to a second embodiment of the present invention;
fig. 10A and 10B are diagrams of the structure and voltage waveforms of an LED driving power-off detection circuit according to a third embodiment of the present invention;
fig. 11A and 11B are diagrams of the structure and voltage waveforms of an LED driving power-off detection circuit according to a fourth embodiment of the present invention;
fig. 12 is a flowchart of a control method of an LED driving power-off detection circuit according to an embodiment of the present invention;
description of reference numerals:
1, an LED drive power-off detection circuit;
11 control module
12 power-off detection module
13 drive module
14 power supply module
15 under-voltage latch module
121 voltage detection circuit
122 timer
123 oscillator.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Before explaining the LED driving power-off detection circuit, the LED lighting device and the control method provided in the embodiments of the present invention, a structure and a principle of an existing LED driving circuit are briefly explained. Referring to fig. 1A and 1B, in the LED driving circuit in the dashed line frame, the power supply module obtains electric energy from the bus, and the power supply module supplies power to the control module, and the control module is according to ICSSampling current feedback, controlling the power tube M1 through the driving module, wherein the principle of the under-voltage latch mechanism is as follows: when the bus voltage VMAnd when the power failure and undervoltage detection module determines that the undervoltage latch point is reached, the RSET signal is sent to reset the control module, and the undervoltage latch state is entered.
This type of circuit suffers from the following problems: a capacitor C1 is connected between the bus and the ground, after the LED driving circuit is powered off, because a large amount of charges are stored in the capacitor C1, the voltage of the capacitor C1 can be lowered to an undervoltage latch point of the undervoltage detection module for a long time, when the bus is powered off, the LED driving circuit can be continuously supplied with energy, but the real bus voltage is not enough to maintain the normal work of each component in the circuit, and the end of the charge discharge on the capacitor C1 needs to be waited from the start of the power failure of the bus to the real entering of an undervoltage latch state. For example, referring to a time period from t1 to t2 in fig. 1B, when the bus starts to be powered down at t1, and when the bus recovers to be powered up at t2 before the undervoltage latch point is reached, in this time period, since components inside the LED driving circuit are not reset (RSET is high level, that is, invalid level), the operation is continued from the current invalid state, so that the fault or damage of the whole circuit is easily caused, and the normal use of the LED driving circuit is affected.
In order to solve the problem that after the existing LED drive circuit is powered off (or powered off), the whole LED drive circuit is continuously supplied with electric energy to keep a working state due to energy storage of a capacitor in the circuit, but the voltage is unstable low voltage at the moment, so that the whole LED drive circuit can work unstably when power supply is restored again, the embodiment of the invention provides an LED drive circuit (hereinafter referred to as an LED drive power-off detection circuit for short) capable of realizing power-off detection, an LED lighting device and a control method of the LED drive power-off detection circuit.
The following describes the LED driving power-off detection circuit provided in the embodiment of the present invention in detail with reference to the accompanying drawings.
The embodiment of the invention provides an LED drive power-off detection circuit, which comprises: the power failure detection module is used for detecting power failure; the power failure detection module comprises a sampling end and a reset signal output end;
the sampling end of the power-off detection module is connected with a power-off detection point of the LED drive power-off detection circuit; the reset signal output end is connected with the control module;
the power-off detection module is used for outputting a reset signal to the control module through the reset signal output end when the LED driving power-off detection circuit is determined to be in a power-off state according to the voltage or the current detected by the sampling end.
In the LED driving power-off detection circuit provided in the embodiment of the present invention, the power-off detection module can collect the voltage or current of the LED driving power-off detection circuit according to the preset power-off sampling point in the LED driving power-off detection circuit, and when the LED driving power-off detection circuit is determined to be in the power-off state according to the voltage or current detected by the sampling terminal, the control module can be timely reset in the abnormal working state before entering the under-voltage latch state when the LED driving power-off detection circuit is in the power-off state by sending the reset signal to the control module, so as to ensure that the LED driving power-off detection circuit can normally work when the LED driving power-off detection circuit is powered on again, thereby avoiding that the device in the LED driving power-off detection circuit is in the unstable working state due to the fact that the capacitor in the circuit continues to supply energy to the LED driving power-off detection circuit, and the actual bus voltage is not enough to maintain the normal working of the LED driving power-off detection circuit, when the bus is electrified again, the problem of failure or damage of the LED drive power-off detection circuit is easily caused.
For the LED driving power-off detection circuit, after power-off, the voltage or current at each position point in the LED driving power-off detection circuit will be attenuated, and the power-off detection point may be a voltage power-off detection point, which may be in various ways, and is convenient for collection and calculation, for example, the power-off detection point is located at any point on the bus, or the power-off detection point is the drain end of the power tube M1 connected to the driving module.
Referring to the example shown in fig. 2, in the LED driving power-off detection circuit 1 (the circuit shown by the dotted line frame in fig. 2) shown in fig. 2, the LED driving power-off detection circuit includes, in addition to the control block 11 and the power-off detection block 12: a drive module 13; one end of the driving module 13 is connected with the control module 11, and the other end is connected with the power tube M1;
the sampling terminal of the power-down detection module 12 is connected to the drain terminal of the power transistor M1.
Referring to the example shown in fig. 3, in the LED driving power-off detection circuit 1 shown in fig. 3 (the circuit shown by the dashed line frame in fig. 3), the sampling terminal of the power-off detection module 12 is connected to the power-off detection point on the bus of the LED driving power-off detection circuit.
The voltage sampling is carried out from the drain end of the power tube M1, compared with the voltage sampling from the bus, because the voltage value detected from the power tube M1 is smaller than that detected from the bus, the waveform difference of the drain end is obvious between the power-off state and the power-on state in the mode of carrying out the voltage sampling from the drain end of the power tube M1, an over-precise detection circuit is not needed, and the judgment is easy.
In the above embodiment, the power-off detection module 12 compares the sampled voltage with a preset reference voltage to determine whether the current power-off state is present. The voltage value of the preset reference voltage can be predetermined according to the voltage of the power-off detection point under the condition of normal voltage.
The bus voltage sampling has the advantages that when power failure begins, the bus reacts with the power failure most timely, and the reactions of other positions in the LED drive power failure detection circuit have hysteresis, so that the power failure can be judged to arrive more timely through bus sampling.
Meanwhile, for the sampling position of sampling, the bus and the sampling point can be sampled simultaneously, and the advantages of the bus and the sampling point are integrated.
And when the bus sampling and the sampling point sampling both enter a power-down state, judging that the system enters the power-down state.
The work flow of the outage detection module 12 is shown with reference to fig. 4, and includes the following steps:
s41, acquiring sampled voltage or current;
s42, judging whether the LED driving power-off detection circuit enters a power-off state or not according to the obtained voltage or current;
and S43, if the LED drive power-off detection circuit enters a power-off state, resetting a control module in the LED drive power-off detection circuit.
In one embodiment, referring to fig. 5, the power outage detection module 12 includes: a voltage detection circuit 121 and a timer 122 connected to the voltage detection circuit 121;
the voltage detection circuit 121 has the sampling terminal and a detection result signal output terminal; the timer 122 is connected with the signal output end of the detection result;
the timer 122 has a reset signal output terminal;
the voltage detection circuit 121 is configured to determine whether the LED driving power-off detection circuit is powered off (at this time, it is not necessarily a power-off state) according to the voltage detected by the sampling terminal, and output a power-off signal to the timer 122 to trigger the timer 122 to time when determining power-off;
the timer 122 is configured to output a reset signal through the reset signal output terminal when the counted time reaches a preset time threshold.
The preset time length threshold value is more than or equal to the period T of the bus voltage after the rectifier bridge in the LED drive power-off detection circuit. The reason for this is that the voltage of the bus is periodically changed, the waveform of the bus is a half-period sine wave, and the half-period sine wave gradually attenuates after the wave peak, so that even in a normal state (without power failure), a value lower than the reference voltage is still present.
Referring to fig. 5, the power outage detection module 12 further includes: an Oscillator (OSC)123, the oscillator 123 is connected to the timer 122, and a clock signal is input to the timer 122.
Of course, the timer according to the embodiment of the present invention is not limited to the above specific implementation, and any circuit capable of implementing a timing function may be selected.
In one embodiment, referring to FIG. 6, the voltage detection circuit 121 is a comparator having two inputs, one of which is a sampling terminal (e.g., V)DETSignal) and the other input is a reference voltage input (V)REF) The output terminal of the comparator is a detection result signal output terminal (EN signal).
The detection result signal EN includes a signal having a sampled voltage lower than the reference voltage input terminal or a signal having a sampled voltage higher than the reference voltage.
In one embodiment, referring to fig. 5, the outage detection module 12 further includes: a resistor R1 and a resistor R2 connected in series; wherein:
the sampling terminal of the voltage detection circuit 121 is connected between the resistor R1 and the resistor R2, and is connected to a power-off detection point of the LED driving power-off detection circuit through the resistor R1, and the resistor R2 is grounded.
In the embodiment of the present invention, since the bus voltage is larger, if the bus voltage is different from the operating voltage of the voltage detection circuit 121, the bus voltage needs to be divided by the resistor R1 and the resistor R2 to obtain a voltage value suitable for the voltage detection circuit 121, and then the voltage value is transmitted to the voltage detection circuit 121, so that the voltage detection circuit 121 compares the voltage value with the reference voltage.
In an embodiment, the voltage detection circuit 121 is specifically configured to compare the value of the voltage detected by the sampling terminal with a preset reference voltage value, and determine that the LED driving power-off detection circuit is powered off (not necessarily in a power-off state) when the value of the voltage detected by the sampling terminal is smaller than the preset reference voltage value, where the reference voltage value V is a value of the reference voltagerefSatisfies the following conditions:
Figure BDA0002628969770000111
Vpis the peak value of the bus voltage or the drain terminal voltage of the power tube M1, r1Is the resistance value of the resistor R1, R2Is the resistance value of the resistor R2.
In one embodiment, referring to fig. 2 or 3, the LED driving power-off detection circuit further includes: the power supply module 14 is connected with a bus, and the under-voltage latch module 15 is connected with the power supply module 14; one end of the under-voltage latch module 15 is connected with the power supply module 15, and the other end of the under-voltage latch module 15 is respectively connected with the control module 11 and the power failure detection module 12;
and the under-voltage latch module 15 is configured to send a reset signal (which may also be referred to as a reset signal) to the power-off detection module 12 and the control module 11 respectively when it is determined that the voltage value output by the power supply module 14 reaches a preset under-voltage latch point.
In the LED driving power-off detection circuit, the undervoltage latch module 15 determines whether the entire LED driving power-off detection circuit enters the undervoltage latch state through the working voltage of the power supply module 14, rather than determining through the bus voltage of the LED driving power-off detection circuit, the voltage values of the two voltages are not equal because of the existence of the energy storage capacitor C1, when the bus voltage is reduced, the energy storage capacitor C1 can stabilize the voltage, and it is ensured that the working voltage of the power supply module is normal, but this normal state is a non-steady state, and it can be realized only by the periodic charging of the energy storage capacitor C1 with the help of the bus voltage, when the bus is powered off, the next period cannot continue to charge, and therefore cannot continue to charge. At this time, the device in the LED driving power-off detection circuit is in an unstable working state, and when the LED driving power-off detection circuit is powered on again, the problem of circuit failure or abnormal operation easily occurs. In order to solve the problem, in the embodiment of the invention, a power failure detection module 12 is added in the LED driving power failure detection circuit, if the LED driving power failure detection circuit is powered down, the power failure detection module 12 can judge that the LED driving power failure detection circuit enters a power failure state before an undervoltage latch module 15 in the LED driving power failure detection circuit judges that the voltage of a control module 11 does not reach an undervoltage latch point, so as to send a reset signal to the control module 11 in time to reset the control module 11 until the LED driving power failure detection circuit recovers power supply, if the voltage value of a power supply module 14 does not reach a preset undervoltage latch point when the power supply is recovered, the undervoltage latch module does not work, and if the voltage of the power supply module 14 in the LED driving power failure detection circuit continuously drops and is undervoltage until the latch module 15 judges that the undervoltage latch point is reached, the undervoltage latch module 15 starts the protection measures of undervoltage latch, and at this time, a reset signal is sent to the control module 11 and the power failure detection module 12 at the same time, and under the control of the reset signal, neither the control module 11 nor the power failure detection module 12 can work normally until the power failure detection circuit of the LED driver is powered on again.
It should be noted that, in the embodiments of fig. 2 to fig. 6, the schemes for performing power-off detection by sampling voltage are shown, and the implementation principle of the schemes for performing power-off detection by sampling current is similar to this, and is not described herein again.
In order to better explain the structure and the operation principle of the LED driving power-off detection circuit provided by the embodiment of the invention, several specific embodiments are described in detail below.
The first embodiment is as follows:
referring to fig. 7A, the LED driving power-off detection circuit obtains energy from the bus through the power supply module, the power supply module supplies power to the control module, and the control module controls the power tube M1 through the driving module according to the fed Ics sampled current. Capacitor C1 has one end connected to the bus and the other end connected to ground.
Wherein the sampling terminal of the power failure detection module is connected to the bus, that is, the resistor R1 and the resistor R2 in the power failure detection module are connected in series to the bus VMThe method is used for sampling the bus voltage to obtain a voltage signal V related to the bus voltageDET(ii) a The voltage detection circuit converts the voltage signal VDETIs equal to a predetermined reference voltage VREFMaking a comparison when VDETValue ratio V of voltageREFWhen the voltage value is high, the EN signal, which is a detection result signal output from the voltage detection circuit, is at a low level. When V isDETVoltage ratio VREFWhen the voltage is low, the detection result signal EN output from the voltage detection circuit is at a high level. In this embodiment EN is active at high level; (of course, the output signal may also be inverted, i.e. when V isDETVoltage ratio VREFWhen the voltage is high, the output EN of the voltage detection circuit is at a high level. When V isDETVoltage ratio VREFWhen the voltage is low, the output EN of the voltage detection circuit is at a low level, and EN is active when it is at a low level).
Wherein VREFThe value of r1+ r2)/r2 is less than or equal to the bus voltage VMPeak value of (V)p. Wherein R1 is the resistance of the resistor R1, and R2 is the resistance of the resistor R2.
The OSC module is configured to provide a Clock (CLK) signal to the timing module, and when EN is at a high level, the timer is enabled and starts timing, and compares the enable signal with an internally set time threshold value Tth, where the value of Tth is greater than or equal to one period T of a bus behind the rectifier bridge, and in the first embodiment, Tth is set to 2T, so as to improve reliability of power failure detection and prevent false triggering; when the duration time of the timer is longer than Tth (2T), the LED drive power-off detection circuit is judged to be in a power-off state, a timing module (Countor module) in the power-off detection module sends an effective RSET1 signal to the control module, and the control module is controlled to enter a reset state until the LED drive power-off detection circuit is detected to be powered on again, so that the LED drive power-off detection circuit can normally work when being powered on again.
Referring to FIG. 7B, VACIf the input voltage is the input voltage before rectification, the period of the bus voltage waveform after rectification is T, the power failure occurs at the time T1 of the LED drive power failure detection circuit (hereinafter, the voltage waveform is a dotted line), and the power supply is recovered at the time T2.
Between time T1 and time T2, the EN signal is active (low) for a duration exceeding the predetermined threshold 2T, so that the power down detection module triggers an active RSET1 signal (low) to the control module.
Between the time t1 and the time t2, the voltage detected by the under-voltage latch module (the operating voltage of the power supply module) is not always lower than the preset under-voltage latch voltage point, so that the under-voltage latch module continuously outputs a high level.
The working flow of the power-off detection module is shown in fig. 8, and the power-off detection module is used for detecting the bus voltage VDETAnd sampling to obtain bus voltage information. Then V is putDETAnd VREFBy comparison, if VDETLess than VREFMeter for measuringThe timer starts to time and judges whether the time reaches the threshold time TthIf yes, the reset signal RSET1 is output.
Example two:
referring to fig. 9A, an example of the LED driving power-off detection circuit according to the second embodiment is similar to the first embodiment, except that the sampling terminal of the power-off detection module is connected to the drain of the power transistor M1, and the drain voltage V is collectedDRNOther structures and operation principles are similar to those of the first embodiment, and are not described in detail herein.
Fig. 9B is a corresponding voltage waveform diagram, wherein power failure occurs at time t1 (hereinafter, the voltage waveform is shown in a dotted line) of the LED driving power-off detection circuit, and power supply is resumed at time t2, and the working principle shown in each waveform diagram is similar to that of the first embodiment and is not described herein again.
Example three:
referring to fig. 10A, an example of an LED driving power-off detection circuit according to a third embodiment is similar to the first embodiment, except that a capacitor C1 is connected in parallel across the LED load.
The voltage waveform diagram (i.e., fig. 10B) and the operation principle and process are similar to those of the first to second embodiments, and will not be described in detail here.
Example four:
referring to fig. 11A, an example of the LED driving power-off detection circuit provided in the third embodiment is similar to the second embodiment, except that a capacitor C1 is connected in parallel across the LED load.
The voltage waveform diagram (i.e., fig. 11B) and the operation principle and process are similar to those of the first to third embodiments, and will not be described in detail here.
The LED driving power-off detection circuit provided in the foregoing embodiment may be applicable to various LED loads, including but not limited to LED lamps, and the like, which is not limited in this embodiment of the present invention.
The embodiment of the invention also provides the LED lighting equipment, which comprises the LED drive power-off detection circuit and an LED lamp connected with the LED drive power-off detection circuit.
Based on the same inventive concept, the embodiment of the invention also provides a control method of the LED driving power-off detection circuit, and as the principle of the method is similar to that of the LED driving power-off detection circuit and the LED lighting device, the implementation of the method can refer to the implementation of the LED driving power-off detection circuit, and repeated parts are not repeated.
The embodiment also provides a control method of the LED driving power-off detection circuit, which is shown in fig. 12 and includes the following steps:
s11, collecting the voltage or current value of a power-off detection point preset by the LED drive power-off detection circuit;
s12, judging whether the LED driving power-off detection circuit is in a power-off state or not according to the acquired voltage or current value and a preset reference voltage value or reference current value; if yes, go to step S13;
and S13, controlling the control module in the LED drive power-off detection circuit to reset.
Optionally, in the step S12, determining whether the LED driving power-off detection circuit is in a power-off state according to the collected voltage value and a preset reference voltage value, where the determining may be implemented by:
judging whether the LED driving power-off detection circuit is powered off or not according to the voltage detected by the sampling end, and determining that the LED driving power-off detection circuit is in a power-off state when the power-off duration time reaches a preset time threshold; the time length threshold value is larger than the period T of the rectified bus voltage.
Optionally, the step of determining whether the LED driving power-off detection circuit is powered off according to the voltage detected by the sampling terminal may be specifically implemented by the following steps:
comparing the voltage value detected by the sampling end with a preset reference voltage value, if the voltage value is smaller than the reference voltage value, judging that the LED drive power-off detection circuit is powered off, and judging that the reference voltage value V is the voltage VrefSatisfies the following conditions:
Figure BDA0002628969770000151
Vpis the peak value of the bus voltage or the voltage at the drain end of the power tube, r1Is the resistance value of the resistor R1, R2Is the resistance value of the resistor R2.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (13)

1. An LED drive power-off detection circuit (1) comprising: a control module (11) and a power failure detection module (12); the power failure detection module (12) comprises a sampling end and a reset signal output end;
the sampling end of the power-off detection module (12) is connected with a power-off detection point of the LED drive power-off detection circuit; the reset signal output end is connected with the control module;
the power-off detection module (12) is used for outputting a reset signal to the control module through the reset signal output end when the LED driving power-off detection circuit is determined to be in a power-off state according to the voltage or the current detected by the sampling end.
2. The circuit of claim 1, wherein the LED drive power down detection circuit further comprises: one end of the driving module (13) is connected with the control module, and the other end of the driving module (13) is connected with a power tube M1;
the sampling end of the power-off detection module (12) is connected with the drain end of the power tube M1.
3. The circuit of claim 1, wherein the sampling terminal of the power-off detection module (12) is connected to a power-off detection point on a bus of the LED driving power-off detection circuit.
4. A circuit according to any one of claims 1 to 3, characterized in that said power-down detection module (12) comprises: a voltage detection circuit (121) and a timer (122) connected to the voltage detection circuit (121);
the voltage detection circuit (121) is provided with the sampling end and a detection result signal output end; a timer (122) is connected with the signal output end of the detection result;
the timer (122) is provided with the reset signal output end;
the voltage detection circuit (121) is used for judging whether the LED driving power-off detection circuit is powered off or not according to the voltage detected by the sampling end, and outputting the power-off signal to the timer (122) to trigger the timer (122) to time when the power-off is judged;
the timer (122) is used for determining that the LED driving power-off detection circuit is in a power-off state when the timing reaches a preset duration threshold value, and outputting a reset signal through the reset signal output end.
5. The circuit of claim 4, wherein the outage detection module (12) further comprises: and an oscillator (123), wherein the oscillator (123) is connected with the timer (122), and a clock signal is input into the timer (122).
6. The circuit of claim 4, wherein the voltage detection circuit (121) is a comparator having one input terminal as the sampling terminal and another input terminal as a reference voltage input terminal, and an output terminal as the detection result signal output terminal.
7. The circuit of claim 4, wherein the outage detection module (12) further comprises: a resistor R1 and a resistor R2 connected in series;
the sampling end of the voltage detection circuit (121) is connected between the resistor R1 and the resistor R2, and is connected with a power-off detection point of the LED driving power-off detection circuit through the resistor R1, and the resistor R2 is grounded.
8. The circuit according to claim 7, wherein the voltage detection circuit (121), in particular for correlating the value of the voltage detected by the sampling terminal with a preset valueIf the reference voltage value is less than the reference voltage value, the LED drive power-off detection circuit is judged to be powered off, and the reference voltage value V isrefSatisfies the following conditions:
Figure FDA0002628969760000021
Vpis the peak value of the bus voltage or the voltage at the drain end of the power tube, r1Is the resistance value of the resistor R1, R2Is the resistance value of the resistor R2.
9. The circuit of any of claims 1-3, further comprising: the device comprises a power supply module (14) and an under-voltage latch module (15), wherein the power supply module (14) is connected with a bus; one end of the under-voltage latch module (15) is connected with the power supply module (14), and the other end of the under-voltage latch module is respectively connected with the control module and the power failure detection module (12);
and the under-voltage latch module (15) is used for respectively sending reset signals to the power failure detection module (12) and the control module when the voltage value output by the power supply module (14) is judged to reach a preset under-voltage latch point.
10. An LED lighting device, characterized in that the LED lighting device comprises the LED drive power-off detection circuit as claimed in any one of claims 1 to 9 and an LED lamp connected with the LED drive power-off detection circuit.
11. A control method of an LED drive power-off detection circuit is characterized by comprising the following steps:
collecting the voltage or current value of a power-off detection point preset by an LED drive power-off detection circuit;
judging whether the LED driving power-off detection circuit is in a power-off state or not according to the acquired voltage or current value and a preset reference voltage value or reference current value;
if the LED driving power-off detection circuit is judged to be yes, the control module in the LED driving power-off detection circuit is controlled to reset.
12. The method of claim 11, wherein determining whether the LED driving power-off detection circuit is in a power-off state according to the collected voltage value and a preset reference voltage value comprises:
judging whether the LED driving power-off detection circuit is powered off or not according to the voltage detected by the sampling end, and determining that the LED driving power-off detection circuit is in a power-off state when the power-off duration time reaches a preset time threshold; the time length threshold value is larger than the period T of the rectified bus voltage.
13. The method of claim 12, wherein determining whether the LED driving power-down detection circuit is powered down according to the voltage detected by the sampling terminal comprises:
comparing the voltage value detected by the sampling end with a preset reference voltage value, if the voltage value is smaller than the reference voltage value, judging that the LED drive power-off detection circuit is powered off, and judging that the reference voltage value V is the voltage VrefSatisfies the following conditions:
Figure FDA0002628969760000031
Vpis the peak value of the bus voltage or the voltage at the drain end of the power tube, r1Is the resistance value of the resistor R1, R2Is the resistance value of the resistor R2.
CN202010805491.2A 2020-08-12 2020-08-12 LED drive power-off detection circuit, LED lighting equipment and control method Pending CN114080080A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1630153A (en) * 2003-12-17 2005-06-22 本田技研工业株式会社 Power supply apparatus
CN103929854A (en) * 2014-04-02 2014-07-16 深圳市明微电子股份有限公司 LED drive device and LED dimming controller thereof
CN205830088U (en) * 2016-06-15 2016-12-21 陕西亚成微电子股份有限公司 A kind of light adjusting circuit
CN206963154U (en) * 2017-07-26 2018-02-02 无锡麟力科技有限公司 By the control circuit for detecting power switch action regulation light-source brightness
CN212573043U (en) * 2020-08-12 2021-02-19 美芯晟科技（北京）有限公司 LED drive outage detection circuit and LED lighting equipment

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1630153A (en) * 2003-12-17 2005-06-22 本田技研工业株式会社 Power supply apparatus
CN103929854A (en) * 2014-04-02 2014-07-16 深圳市明微电子股份有限公司 LED drive device and LED dimming controller thereof
CN205830088U (en) * 2016-06-15 2016-12-21 陕西亚成微电子股份有限公司 A kind of light adjusting circuit
CN206963154U (en) * 2017-07-26 2018-02-02 无锡麟力科技有限公司 By the control circuit for detecting power switch action regulation light-source brightness
CN212573043U (en) * 2020-08-12 2021-02-19 美芯晟科技（北京）有限公司 LED drive outage detection circuit and LED lighting equipment

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