LED driving circuit, LED driving power supply and LED driving system applied to two-wire programming

Abstract

The invention relates to an LED driving circuit, an LED driving power supply and an LED driving system applied to two-wire programming. The LED driving circuit comprises a voltage division circuit, a switch control circuit, a first isolation circuit, a second isolation circuit, a voltage stabilizing circuit and a main control unit, the voltage division circuit generates a detection signal; the switch control circuit awakens the main control unit, is continuously conducted according to a delay conduction signal output by the main control unit after being conducted, and is disconnected after the delay time is reached; the main control unit is started to work according to the wake-up signal and judges whether an offline state exists or not according to the detection signal, if yes, a delay conduction signal is sent, and if not, the delay conduction signal is not sent; the second isolation circuit transmits a power supply signal of the internal auxiliary power supply port to the voltage stabilizing circuit. According to the invention, the fault driving power supply can be disconnected from the parallel operation network in the case of abnormity or fault, so that problems occurring under the condition of parallel operation use can be avoided, and normal use of the two-wire burning function can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of LED driving power supplies, and more specifically, to an LED driving circuit, an LED driving power supply and an LED driving system applied to two-wire programming. Background Art

[0002] At present, the programmability of output current and additional functions has become the standard configuration of LED driver power supplies, especially intelligent LED driver power supplies. In order to facilitate production, debugging and use, offline programming has gradually become the mainstream configuration, and offline two-wire programming is increasingly favored by end users because it can realize programming without providing additional power supply. In the two-wire programming method, the programming line and the dimming line are used, that is, the dimming line and the programming line are shared. When used in parallel, the dimming lines of all LED driver power supplies are connected in parallel to the controller to realize joint operation startup, shutdown and dimming control. The basic working principle of offline two-wire programming is: during offline programming, the MCU circuit directly draws power from the programming signal line, that is, the programming line also powers the MCU while programming (power supply circuit 1). When the LED driver power supply is powered on and working normally, the MCU is powered by the auxiliary winding (power supply circuit 2).

[0003] However, the existing two-wire programming circuit has the following defects:

[0004] 1. In the case of parallel use, if the power supply circuit 2 of one or more LED driver power supplies is abnormal (such as driver damage, AC input line abnormality), the MCU will draw power from the power supply circuit 1, which will cause the dimming line voltage to be lowered, the output current of the LED driver power supply to drop, and the brightness of the lamp to become lower, especially when the controller driving capacity is insufficient or multiple LED driver power supplies are abnormal at the same time;

[0005] 2. When used in parallel, if the MCU power supply of one or more LED driver power supplies is short-circuited, the faulty LED driver power supply will pull the dimming line voltage of the entire system down to an extremely low level, causing the entire system to shut down;

[0006] 3. When used in parallel, if one or more LED driver power supplies are operating in hiccup mode (such as output short circuit), the faulty LED driver power supply will intermittently draw power from power supply circuit 1, thereby lowering the dimming light voltage of the entire system, causing the entire system to have a light flickering problem. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide an LED driving circuit, an LED driving power supply and an LED driving system for two-wire programming in view of the problems existing in the prior art.

[0008] The technical solution adopted by the present invention to solve the technical problem is: constructing an LED driving circuit applied to two-line programming, including: a voltage dividing circuit, a switch control circuit, a first isolation circuit, a second isolation circuit, a voltage stabilizing circuit and a main control unit;

[0009] The input end of the voltage divider circuit is connected to the internal auxiliary power supply port, the output end of the voltage divider circuit is connected to the detection end of the main control unit, the input end of the switch control circuit is connected to the burning / dimming signal port, the output end of the switch control circuit is connected to the input end of the first isolation circuit, the output end of the first isolation circuit is connected to the input end of the voltage stabilizing circuit, the input end of the second isolation circuit is connected to the internal auxiliary power supply port, the output end of the second isolation circuit is connected to the input end of the voltage stabilizing circuit, the output end of the voltage stabilizing circuit is connected to the power supply end of the main control unit, and the main control unit is also connected to the switch control circuit;

[0010] The voltage divider circuit is used to detect the power supply signal of the internal auxiliary power supply port and generate a detection signal;

[0011] The switch control circuit is used to be turned on according to the burning signal of the burning / dimming signal port during offline burning so as to transmit the wake-up signal to the main control unit through the first isolation circuit and the voltage stabilizing circuit in sequence, and to be continuously turned on according to the delayed turn-on signal output by the main control unit after being turned on, and to be turned off after the delay time is reached;

[0012] The main control unit is used to start working according to the wake-up signal, and after starting working, judge whether it is in an offline state according to the detection signal, if so, send the delayed conduction signal to the switch control circuit, if not, do not send the delayed conduction signal;

[0013] The second isolation circuit is used to transmit the power supply signal of the internal auxiliary power supply port to the voltage stabilizing circuit.

[0014] In the LED driving circuit for two-wire programming described in the present invention, the switch control circuit includes: an isolation switch, a wake-up circuit and a PWM detection circuit;

[0015] The first end of the isolation switch and the input end of the wake-up circuit are connected to the internal auxiliary power supply port, the second end of the isolation switch is connected to the wake-up circuit, the third end of the isolation switch is connected to the input end of the first isolation circuit, the input end of the PWM detection circuit is connected to the main control unit, and the output end of the PWM detection circuit is connected to the wake-up circuit;

[0016] The wake-up circuit is used to control the isolation switch to be turned on according to the burning signal of the burning / dimming signal port during offline burning, so as to transmit the wake-up signal to the first isolation circuit through the isolation switch; the PWM detection circuit is used to receive the delayed conduction signal output by the main control unit, and control the isolation switch to be continuously turned on according to the delayed conduction signal, and control the isolation switch to be turned off after the delay time is reached.

[0017] In the LED driving circuit for two-wire programming described in the present invention, the wake-up circuit includes: a unidirectional conduction circuit, a first RC network, a second RC network, a wake-up switch and a control switch;

[0018] The input end of the unidirectional conduction circuit is connected to the burning / dimming signal port, the output end of the unidirectional conduction circuit is connected to the input end of the first RC network and the input end of the second RC network, the output end of the first RC network is connected to the first end of the wake-up switch, the output end of the second RC network is connected to the second end of the wake-up switch, the third end of the wake-up switch is connected to the input end of the control switch, the output end of the control switch is connected to the second end of the isolation switch, and the control end of the control switch is connected to the PWM detection circuit.

[0019] In the LED driving circuit for two-wire programming described in the present invention, the unidirectional conduction circuit includes: a third diode; the first RC network includes: a second resistor, a third resistor and a first capacitor; the second RC network includes: a fourth resistor, a fifth resistor and a second capacitor; the wake-up switch includes: a second MOS tube; the control switch includes: a sixth resistor and a third MOS tube;

[0020] The anode of the third diode is connected to the burning / dimming signal port, the cathode of the third diode is connected to the first end of the second resistor and the first end of the fourth resistor, the second end of the second resistor is connected to the first end of the third resistor, the first end of the first capacitor and the source of the second MOS tube, and the second end of the third resistor and the second end of the first capacitor are grounded; the second end of the fourth resistor is connected to the first end of the fifth resistor, the first end of the second capacitor and the gate of the second MOS tube, and the second end of the fifth resistor and the second end of the second capacitor are grounded;

[0021] The drain of the second MOS tube is connected to the first end of the sixth resistor, the second end of the sixth resistor is connected to the gate of the third MOS tube, the gate of the third MOS tube is also connected to the PWM detection circuit, the drain of the third MOS tube is connected to the second end of the isolation switch, and the source of the third MOS tube is grounded.

[0022] In the LED driving circuit applied to two-wire programming described in the present invention, the resistance value of the second resistor is the same as the resistance value of the fourth resistor, the resistance value of the third resistor is the same as the resistance value of the fifth resistor, and the capacitance of the first capacitor is smaller than the capacitance of the second capacitor.

[0023] In the LED driving circuit for two-wire programming described in the present invention, the PWM detection circuit includes: a seventh resistor, a third capacitor, a fourth capacitor, a fourth diode and a fifth diode;

[0024] The first end of the seventh resistor, the first end of the third capacitor and the cathode of the fourth diode are connected to the gate of the third MOS tube, the second end of the seventh resistor, the second end of the third capacitor and the anode of the fifth diode are grounded, the anode of the fourth diode is connected to the cathode of the fifth diode and the first end of the fourth capacitor, and the second end of the fourth capacitor is connected to the main control unit.

[0025] In the LED driving circuit for two-wire programming described in the present invention, the voltage divider circuit includes: a twelfth resistor and a thirteenth resistor;

[0026] The first end of the twelfth resistor is connected to the internal auxiliary power supply port, the second end of the twelfth resistor is connected to the first end of the thirteenth resistor and the detection end of the main control unit, and the second end of the thirteenth resistor is grounded.

[0027] In the LED driving circuit for two-wire programming described in the present invention, the first isolation circuit includes: a first diode; the second isolation circuit includes: a second diode; the voltage stabilizing circuit includes: a ninth resistor, a tenth resistor, an eleventh resistor, a reference device, a fifth capacitor and a fourth transistor;

[0028] The anode of the first diode is connected to the output end of the switch control circuit, the anode of the first diode is connected to the emitter of the fourth transistor and the cathode of the second diode, the anode of the second diode is connected to the internal auxiliary power supply port, the emitter of the fourth transistor is connected to the power supply end of the main control unit, the base of the fourth transistor is connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the second end of the reference device and the second end of the tenth resistor, and the first end of the tenth resistor is connected to the emitter of the fourth transistor;

[0029] The first end of the ninth resistor is connected to the collector of the fourth transistor, the second end of the ninth resistor is connected to the base of the fourth transistor and the first end of the reference device, the third end of the reference device and the second end of the eleventh resistor are grounded, and the second end of the tenth resistor is connected to the first end of the eleventh resistor.

[0030] The present invention also provides an LED driving power supply, comprising: the above-mentioned LED driving circuit applied to two-wire programming.

[0031] The present invention further provides an LED driving system, comprising: a plurality of LED driving power supplies used in parallel, each of the LED driving power supplies comprising the above-mentioned LED driving circuit applied to two-wire programming.

[0032] The LED driving circuit, LED driving power supply and LED driving system for two-wire programming of the present invention have the following beneficial effects: including: a voltage dividing circuit, a switch control circuit, a first isolation circuit, a second isolation circuit, a voltage stabilizing circuit and a main control unit; the voltage dividing circuit generates a detection signal; the switch control circuit wakes up the main control unit, and after being turned on, it continues to be turned on according to the delayed conduction signal output by the main control unit and is disconnected after the delay time is reached; the main control unit starts working according to the wake-up signal, and determines whether it is in an offline state according to the detection signal, if so, sends a delayed conduction signal, if not, does not send a delayed conduction signal; the second isolation circuit transmits the power supply signal of the internal auxiliary power supply port to the voltage stabilizing circuit. The present invention can not only disconnect the faulty driving power supply from the parallel network in the event of an abnormality or failure, avoiding problems in the case of parallel use, but also ensure the normal use of the two-wire burning function. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0034] Figure 1 It is a principle block diagram of an LED driving circuit applied to two-wire programming provided by the present invention;

[0035] Figure 2 It is a circuit principle diagram of an LED driving circuit applied to two-wire programming provided by the present invention;

[0036] Figure 3 It is a waveform diagram of the gate, source and VCC voltages of the wake-up switch when DIM+ is powered on provided by the present invention;

[0037] Figure 4 It is a voltage waveform diagram of the gate and source of the wake-up switch when the DIM+ applies a PWM dimming signal provided by the present invention;

[0038] Figure 5 It is a gate voltage waveform diagram of the third MOS tube when a PWM dimming signal is applied to the VG port provided by the present invention;

[0039] Figure 6 It is a gate voltage waveform diagram of the third MOS tube when high and low levels are applied to the VG port provided by the present invention;

[0040] Figure 7 This is the complete power-on burning process provided by the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The present invention sets a switch control circuit in the driving power supply in two-wire programming (i.e., two-wire burning). When the LED driving power supply fails, the dimming line of the failed LED driving power supply can be disconnected from the parallel network in a timely and effective manner, so as to achieve the purpose of not affecting the normal operation of other grid-connected LED driving power supplies, and at the same time ensure the normal use of the two-wire burning function.

[0043] refer to Figure 1 , Figure 1 A principle block diagram of a preferred embodiment of an LED driving circuit for two-wire programming provided by the present invention.

[0044] Specifically, Figure 1 As shown, in this embodiment, the LED driving circuit applied to two-wire programming includes: a voltage dividing circuit 11, a switch control circuit 12, a first isolation circuit 13, a second isolation circuit 14, a voltage stabilizing circuit 15 and a main control unit 16.

[0045] The input end of the voltage divider circuit 11 is connected to the internal auxiliary power supply port, the output end of the voltage divider circuit 11 is connected to the detection end of the main control unit 16, the input end of the switch control circuit 12 is connected to the burning / dimming signal port, the output end of the switch control circuit 12 is connected to the input end of the first isolation circuit 13, the output end of the first isolation circuit 13 is connected to the input end of the voltage stabilizing circuit 15, the input end of the second isolation circuit 14 is connected to the internal auxiliary power supply port, the output end of the second isolation circuit 14 is connected to the input end of the voltage stabilizing circuit 15, the output end of the voltage stabilizing circuit 15 is connected to the power supply end of the main control unit 16, and the main control unit 16 is also connected to the switch control circuit 12.

[0046] The voltage divider circuit 11 is used to detect the power supply signal of the internal auxiliary power supply port and generate a detection signal; the switch control circuit 12 is used to be turned on according to the burning signal of the burning / dimming signal port during offline burning so as to transmit the wake-up signal to the main control unit 16 through the first isolation circuit 13 and the voltage stabilizing circuit 15 in sequence, and to continue to be turned on according to the delayed conduction signal output by the main control unit 16 after being turned on, and to be disconnected after the delay time is reached; the main control unit 16 is used to start the work according to the wake-up signal, and after starting the work, determine whether it is in an offline state according to the detection signal, and if so, send a delayed conduction signal to the switch control circuit 12, if not, do not send a delayed conduction signal; the second isolation circuit 14 is used to transmit the power supply signal of the internal auxiliary power supply port to the voltage stabilizing circuit 15.

[0047] Specifically, through the switch control circuit 12, when programming is performed offline, the switch control circuit 12 can be turned on according to the programming signal, and then the wake-up signal (wherein the wake-up signal is the programming signal) passes through the first isolation circuit 13 and the voltage stabilizing circuit 15 in sequence, and then the power supply voltage is provided to the main control unit 16, so as to achieve the purpose of waking up the main control unit 16. In addition, after the main control unit 16 is awakened, the power supply signal output by the internal auxiliary power supply port is detected by the voltage divider circuit 11 to generate a corresponding detection signal, so that the main control unit 16 can determine whether the current state of the LED driving power supply is offline or online based on the detection signal. If it is determined that the LED driving power supply is currently in an online state, the main control unit 16 controls the switch control circuit 12 to be turned off; if it is determined that the LED driving power supply is currently in an offline state, the main control unit 16 sends a delayed conduction signal to the switch control circuit 12, and then the switch control circuit 12 is continuously turned on through the delayed conduction signal, and is disconnected after the delay time is reached, thereby disconnecting the power supply circuit 1 from the dimming / programming line.

[0048] Optionally, in an embodiment of the present invention, the switch control circuit 12 includes: an isolation switch 121 , a wake-up circuit 122 and a PWM detection circuit 123 .

[0049] The first end of the isolation switch 121 and the input end of the wake-up circuit 122 are connected to the internal auxiliary power supply port, the second end of the isolation switch 121 is connected to the wake-up circuit 122, the third end of the isolation switch 121 is connected to the input end of the first isolation circuit 13, the input end of the PWM detection circuit 123 is connected to the main control unit 16, and the output end of the PWM detection circuit 123 is connected to the wake-up circuit 122; the wake-up circuit 122 is used to control the isolation switch 121 to be turned on according to the burning signal of the burning / dimming signal port during offline burning, so as to transmit the wake-up signal to the first isolation circuit 13 through the isolation switch 121; the PWM detection circuit 123 is used to receive the delayed conduction signal output by the main control unit 16, and control the isolation switch 121 to be continuously turned on according to the delayed conduction signal, and control the isolation switch 121 to be turned off after the delay time is reached.

[0050] Among them, the wake-up circuit 122 includes: a unidirectional conduction circuit, a first RC network, a second RC network, a wake-up switch and a control switch; the input end of the unidirectional conduction circuit is connected to the burning / dimming signal port, the output end of the unidirectional conduction circuit is connected to the input end of the first RC network and the input end of the second RC network, the output end of the first RC network is connected to the first end of the wake-up switch, the output end of the second RC network is connected to the second end of the wake-up switch, the third end of the wake-up switch is connected to the input end of the control switch, the output end of the control switch is connected to the second end of the isolation switch 121, and the control end of the control switch is connected to the PWM detection circuit 123. Specifically, the delayed on-signal sent by the main control unit 16 to the PWM detection circuit 123 is a PWM signal of a fixed frequency. When the PWM detection circuit 123 receives the PWM signal of the fixed frequency, the PWM detection circuit 123 will control the isolation switch 121 to remain on. Since the main control unit 16 stops sending the fixed-frequency PWM signal to the PWM detection circuit 123 after a preset delay time (wherein the delay time is required to ensure the completion of a normal programming), at this time, the PWM detection circuit 123 no longer controls the isolation switch 121 to remain on, that is, controls the isolation switch 121 to be turned off, thereby disconnecting the power supply circuit 1 from the dimming / programming line.

[0051] The principle of the present invention is described below with reference to a specific embodiment.

[0052] refer to Figure 2 , Figure 2 A circuit schematic diagram of a preferred embodiment of an LED driving circuit for two-wire programming provided by the present invention.

[0053] like Figure 2As shown, in this embodiment, Q1 is an isolation switch 121. The unidirectional conduction circuit includes: a third diode D3; a first RC network includes: a second resistor R2, a third resistor R3 and a first capacitor C1; a second RC network includes: a fourth resistor R4, a fifth resistor R5 and a second capacitor C2; a wake-up switch Q2 includes: a second MOS tube; and a control switch includes: a sixth resistor R6 and a third MOS tube Q3.

[0054] The anode of the third diode D3 is connected to the burning / dimming signal port, the cathode of the third diode D3 is connected to the first end of the second resistor R2 and the first end of the fourth resistor R4, the second end of the second resistor R2 is connected to the first end of the third resistor R3, the first end of the first capacitor C1 and the source of the second MOS tube, the second end of the third resistor R3 and the second end of the first capacitor C1 are grounded; the second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5, the first end of the second capacitor C2 and the gate of the second MOS tube, the second end of the fifth resistor R5 and the second end of the second capacitor C2 are grounded; the drain of the second MOS tube is connected to the first end of the sixth resistor R6, the second end of the sixth resistor R6 is connected to the gate of the third MOS tube Q3, the gate of the third MOS tube Q3 is also connected to the PWM detection circuit 123, the drain of the third MOS tube Q3 is connected to the second end of the isolation switch 121, and the source of the third MOS tube Q3 is grounded.

[0055] In the embodiment of the present invention, the resistance of the second resistor R2 is the same as that of the fourth resistor R4, the resistance of the third resistor R3 is the same as that of the fifth resistor R5, and the capacitance of the first capacitor C1 is smaller than that of the second capacitor C2.

[0056] like Figure 2 As shown, in this embodiment, the PWM detection circuit 123 includes: a seventh resistor R7, a third capacitor C3, a fourth capacitor C4, a fourth diode D4 and a fifth diode D5.

[0057] The first end of the seventh resistor R7, the first end of the third capacitor C3 and the cathode of the fourth diode D4 are connected to the gate of the third MOS tube Q3, the second end of the seventh resistor R7, the second end of the third capacitor C3 and the anode of the fifth diode D5 are grounded, the anode of the fourth diode D4 is connected to the cathode of the fifth diode D5 and the first end of the fourth capacitor C4, and the second end of the fourth capacitor C4 is connected to the main control unit 16.

[0058] like Figure 2 As shown, in this embodiment, the voltage divider circuit 11 includes: a twelfth resistor R12 and a thirteenth resistor R13; the first end of the twelfth resistor R12 is connected to the internal auxiliary power supply port, the second end of the twelfth resistor R12 is connected to the first end of the thirteenth resistor R13 and the detection end of the main control unit 16, and the second end of the thirteenth resistor R13 is grounded.

[0059] like Figure 2 As shown, in this embodiment, the first isolation circuit 13 includes: a first diode D1; the second isolation circuit 14 includes: a second diode D2; the voltage stabilizing circuit 15 includes: a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a reference device U1, a fifth capacitor C5 and a fourth transistor Q4.

[0060] Among them, the anode of the first diode D1 is connected to the output end of the switch control circuit 12, the anode of the first diode D1 is connected to the emitter of the fourth transistor Q4 and the cathode of the second diode D2, the anode of the second diode D2 is connected to the internal auxiliary power supply port, the emitter of the fourth transistor Q4 is connected to the power supply end of the main control unit 16, the base of the fourth transistor Q4 is connected to the first end of the fifth capacitor C5, the second end of the fifth capacitor C5 is connected to the second end of the reference device U1 and the second end of the tenth resistor R10, and the first end of the tenth resistor R10 is connected to the emitter of the fourth transistor Q4; the first end of the ninth resistor R9 is connected to the collector of the fourth transistor Q4, the second end of the ninth resistor R9 is connected to the base of the fourth transistor Q4 and the first end of the reference device U1, the third end of the reference device U1 and the second end of the eleventh resistor R11 are grounded, and the second end of the tenth resistor R10 is connected to the first end of the eleventh resistor R11.

[0061] like Figure 2 As shown, V-AUX is the internal auxiliary power supply port of the LED driving power supply (i.e., the power supply signal interface provided by the auxiliary winding), and DIM+ is the burning / dimming signal port. The voltage divider circuit 11 composed of the twelfth resistor R12 and the thirteenth resistor R13 is used to supply the main control unit 16 (MCU, wherein the MCU is Figure 2 (not shown in the figure) detects whether the current state is offline programming.

[0062] like Figure 2As shown, during offline programming, DIM+ and GND will be connected to the programmer. When connected, DIM+ outputs a step level (i.e., the programming signal), and the step level is sent to the source of the wake-up switch Q2 (wherein the wake-up switch Q2 is a P-type MOS tube) through the first RC network composed of the second resistor R2, the third resistor R3 and the first capacitor C1. At the same time, the step level is also sent to the gate of the wake-up switch Q2 through the second RC network composed of the fourth resistor R4, the fifth resistor R5 and the second capacitor C2. When the programmer is connected, the voltage output by DIM+ charges the first capacitor C1 through the second resistor R2, and charges the second capacitor C2 through the fourth resistor R4. Since the resistance value of the second resistor R2 is the same as the resistance value of the fourth resistor R4, and the capacitance value of the first capacitor C1 is smaller than the capacitance value of the second capacitor C2, the voltage rise speed of the first voltage is faster than the voltage rise speed of the second capacitor C2, that is, the source level of the wake-up switch Q2 rises faster than the gate. When the difference between the source level and the gate level of the wake-up switch Q2 is greater than the Vgs (th) of the wake-up switch Q2, the wake-up switch Q2 is turned on, thereby driving the third MOS tube Q3 to turn on, and then controlling the isolation switch 121 to turn on through the third MOS tube Q3. At this time, the voltage output by DIM+ is sent to the voltage regulator circuit 15 through the isolation switch 121 and the first diode D1 to power the MCU, and the MCU starts working, that is, the MCU is awakened.

[0063] After the MUC is awakened, the MCU detects whether the detection signal (VSENS) obtained by dividing the power supply signal output by the twelfth resistor R12 and the thirteenth resistor R13 is a low level (if VSENS is a low level, it means that the current state is offline). If so, the MCU sends a fixed frequency PWM signal to the VG port of the PWM detection circuit 123. After the PWM detection circuit 123 detects the PWM signal sent by the MCU, it will generate a high level at the gate of the third MOS tube Q3. At the same time, the voltage difference between the source level and the gate level of the wake-up switch Q2 gradually decreases. When the voltage Vgs(th) of the wake-up switch Q2 decreases to less than the Vgs(th) of the wake-up switch Q2, Q2 is turned off. At this time, since the PWM detection circuit 123 generates a high level at the gate of the third MOS tube Q3, the third MOS tube Q3 can be continuously turned on, thereby ensuring that DIM+ continues to power the MCU. After the preset delay time, the MCU stops sending the PWM signal to the VG port. At this time, the PWM detection circuit 123 no longer generates a high level at the gate of the third MOS tube Q3, and the third MOS tube Q3 is turned off, thereby controlling the isolation switch 121 to be turned off, thereby disconnecting the power supply circuit 1 from the dimming / programming line.

[0064] Based on the above principle, it can be seen that the present invention uses the time constant difference between the first RC network and the second RC network to provide a short pulse drive for the wake-up switch Q2 during offline programming to wake up the MCU, and then the MCU determines whether to turn on the isolation switch 121 by detecting whether it is currently in an offline state. When DIM+ is a PWM dimming signal, since the resistance value of the second resistor R2 is the same as the resistance value of the fourth resistor R4, and the resistance value of the third resistor R3 is the same as the resistance value of the fifth resistor R5, the gate-source voltage difference of the wake-up switch Q2 is 0, and the wake-up switch Q2 remains off, so the MCU will not be repeatedly woken up, and the voltage of the same voltage will not be affected.

[0065] In addition, due to the PWM detection circuit 123, if the MCU is abnormal or cannot normally send a PWM signal to the VG port, the third MOS can be turned off in time after the wake-up process is completed even in the offline programming state. This is because the PWM detection circuit 123 will only generate a high level at the gate of the third MOS to maintain the conduction of the third MOS tube Q3 when receiving a PWM signal. If the VG port receives a continuous high level or a low level, the gate of the third MOS tube Q3 is always at a low level, and the third MOS tube Q3 is always kept in the off state, so that the isolation switch 121 is always kept in the off state.

[0066] Through the present invention, when the LED driver power supply circuit 2 is used in parallel, if it is abnormal (such as LED driver damage, AC input line abnormality, etc.), because Q1 is cut off, the MCU will not draw power from the power supply circuit 1, the dimming line voltage will not be pulled down, and the normal operation of other LED drivers connected to the network will not be affected. When the MCU power supply of the LED driver power supply is short-circuited, because Q1 is cut off, the MCU will not draw power from the power supply circuit 1, the dimming line voltage will not be pulled down, and the normal operation of other LED drivers connected to the network will not be affected. When the LED driver power supply is used in parallel, if the LED driver power supply works in the hiccup mode due to a fault (such as output short circuit), the VSENS port will generate a high level, and the MCU will determine that it is currently in non-offline mode, and will not send a PWM signal to the VG network. Q1 will remain cut off, and the faulty LED driver power supply will not draw power from the power supply circuit 1, and the normal operation of other LED drivers connected to the network will not be affected.

[0067] like Figure 3 As shown, channel 1 is the voltage waveform of DIM+ output, channel 2 is the source voltage waveform of wake-up switch Q2, channel 3 is the gate voltage waveform of wake-up switch Q2, and channel 4 is the VCC voltage waveform. Figure 3It can be seen that when powered on, the source voltage of the wake-up switch Q2 rises faster than the gate voltage, and the gate-source voltage difference is sufficient to turn on the wake-up switch Q2. After the wake-up switch Q2 is turned on, the isolation switch 121 is turned on, and VCC outputs 5V to power the MCU. When the gate-source voltage difference of the wake-up switch Q2 gradually decreases to the turn-off voltage, the wake-up switch Q2 is turned off. After the wake-up switch Q2 is turned off, the isolation switch 121 is also turned off accordingly, and the VCC voltage drops. This is the MCU wake-up process.

[0068] like Figure 4 As shown, after the wake-up process is completed, the gate and source voltage waveforms of Q2 are displayed when the PWM dimming signal is applied to DIM+. Figure 4 In the figure, channel 1 is the DIM+ voltage signal, channel 2 is the wake-up switch Q2 source voltage waveform, and channel 3 is the wake-up switch Q2 gate voltage waveform. Figure 4 It can be seen that when PWM waveforms with different duty cycles are applied to the DIM+ terminal, the gate and source voltages of the wake-up switch Q2 will change accordingly, but the voltage difference between the gate and source voltages is extremely small, which is not enough to turn on the wake-up switch Q2. That is, during normal operation, the PWM signal on the dimming bus will not generate a wake-up signal for the faulty LED driver power supply.

[0069] like Figure 5 As shown, Figure 5 The gate voltage waveform of the third MOS tube Q3 is shown in Figure 1. The gate voltage waveform of the third MOS tube Q3 is shown in Figure 2. The gate voltage waveform of the third MOS tube Q3 is shown in Figure 3. Figure 5 It can be seen that when a PWM signal is applied to the VG network, the gate of the third MOS tube Q3 will generate a corresponding high level.

[0070] Figure 6 The gate voltage waveform of the third MOS tube Q3 when the VG network applies high and low levels is shown in Figure 2. Figure 6 It can be seen that when high and low levels are applied to the VG network, the gate of the third MOS tube Q3 always maintains a low level.

[0071] Figure 7 This is a complete power-on programming process, where channel 1 is the DIM+ voltage waveform, channel 2 is the VG PWM signal, and channel 3 is the VCC voltage waveform. Figure 7 It can be seen that after the DIM+ terminal is powered on, VCC outputs 5V to wake up the MCU. After the MCU is awakened, it outputs a PWM signal to the VG network to maintain continuous power supply to VCC.

[0072] The present invention further provides an LED driving power supply, which includes the LED driving circuit for two-wire programming disclosed in an embodiment of the present invention.

[0073] The present invention also provides an LED driving system, which includes: a plurality of LED driving power supplies used in parallel. That is, a plurality of LED driving power supplies are arranged in parallel to form a parallel network. Each LED driving power supply is provided with an LED driving circuit for two-wire programming disclosed in an embodiment of the present invention.

[0074] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0075] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0076] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0077] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot limit the scope of protection of the present invention. All equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. An LED driving circuit for two-wire programming, characterized in that: include: A voltage dividing circuit, a switch control circuit, a first isolation circuit, a second isolation circuit, a voltage stabilizing circuit and a main control unit; The input end of the voltage divider circuit is connected to the internal auxiliary power supply port, the output end of the voltage divider circuit is connected to the detection end of the main control unit, the input end of the switch control circuit is connected to the burning / dimming signal port, the output end of the switch control circuit is connected to the input end of the first isolation circuit, the output end of the first isolation circuit is connected to the input end of the voltage stabilizing circuit, the input end of the second isolation circuit is connected to the internal auxiliary power supply port, the output end of the second isolation circuit is connected to the input end of the voltage stabilizing circuit, the output end of the voltage stabilizing circuit is connected to the power supply end of the main control unit, and the main control unit is also connected to the switch control circuit; The voltage divider circuit is used to detect the power supply signal of the internal auxiliary power supply port and generate a detection signal; The switch control circuit is used to be turned on according to the burning signal of the burning / dimming signal port during offline burning so as to transmit the wake-up signal to the main control unit through the first isolation circuit and the voltage stabilizing circuit in sequence, and to be continuously turned on according to the delayed turn-on signal output by the main control unit after being turned on, and to be turned off after the delay time is reached; The main control unit is used to start working according to the wake-up signal, and after starting working, judge whether it is in an offline state according to the detection signal, if so, send the delayed conduction signal to the switch control circuit, if not, do not send the delayed conduction signal; The second isolation circuit is used to transmit the power supply signal of the internal auxiliary power supply port to the voltage stabilizing circuit.

2. The LED driving circuit for two-wire programming according to claim 1, characterized in that: The switch control circuit includes: an isolation switch, a wake-up circuit and a PWM detection circuit; The first end of the isolation switch and the input end of the wake-up circuit are connected to the internal auxiliary power supply port, the second end of the isolation switch is connected to the wake-up circuit, the third end of the isolation switch is connected to the input end of the first isolation circuit, the input end of the PWM detection circuit is connected to the main control unit, and the output end of the PWM detection circuit is connected to the wake-up circuit; The wake-up circuit is used to control the isolation switch to be turned on according to the burning signal of the burning / dimming signal port during offline burning, so as to transmit the wake-up signal to the first isolation circuit through the isolation switch; the PWM detection circuit is used to receive the delayed conduction signal output by the main control unit, and control the isolation switch to be continuously turned on according to the delayed conduction signal, and control the isolation switch to be turned off after the delay time is reached.

3. The LED driving circuit for two-wire programming according to claim 2, characterized in that: The wake-up circuit includes: a unidirectional conduction circuit, a first RC network, a second RC network, a wake-up switch and a control switch; The input end of the unidirectional conduction circuit is connected to the burning / dimming signal port, the output end of the unidirectional conduction circuit is connected to the input end of the first RC network and the input end of the second RC network, the output end of the first RC network is connected to the first end of the wake-up switch, the output end of the second RC network is connected to the second end of the wake-up switch, the third end of the wake-up switch is connected to the input end of the control switch, the output end of the control switch is connected to the second end of the isolation switch, and the control end of the control switch is connected to the PWM detection circuit.

4. The LED driving circuit for two-wire programming according to claim 3, characterized in that: The unidirectional conduction circuit includes: a third diode; the first RC network includes: a second resistor, a third resistor and a first capacitor; the second RC network includes: a fourth resistor, a fifth resistor and a second capacitor; the wake-up switch includes: a second MOS tube; the control switch includes: a sixth resistor and a third MOS tube; The anode of the third diode is connected to the burning / dimming signal port, the cathode of the third diode is connected to the first end of the second resistor and the first end of the fourth resistor, the second end of the second resistor is connected to the first end of the third resistor, the first end of the first capacitor and the source of the second MOS tube, and the second end of the third resistor and the second end of the first capacitor are grounded; the second end of the fourth resistor is connected to the first end of the fifth resistor, the first end of the second capacitor and the gate of the second MOS tube, and the second end of the fifth resistor and the second end of the second capacitor are grounded; The drain of the second MOS tube is connected to the first end of the sixth resistor, the second end of the sixth resistor is connected to the gate of the third MOS tube, the gate of the third MOS tube is also connected to the PWM detection circuit, the drain of the third MOS tube is connected to the second end of the isolation switch, and the source of the third MOS tube is grounded.

5. The LED driving circuit for two-wire programming according to claim 4, characterized in that: The resistance value of the second resistor is the same as the resistance value of the fourth resistor, the resistance value of the third resistor is the same as the resistance value of the fifth resistor, and the capacitance value of the first capacitor is smaller than the capacitance value of the second capacitor.

6. The LED driving circuit for two-wire programming according to claim 5, characterized in that: The PWM detection circuit comprises: a seventh resistor, a third capacitor, a fourth capacitor, a fourth diode and a fifth diode; The first end of the seventh resistor, the first end of the third capacitor and the cathode of the fourth diode are connected to the gate of the third MOS tube, the second end of the seventh resistor, the second end of the third capacitor and the anode of the fifth diode are grounded, the anode of the fourth diode is connected to the cathode of the fifth diode and the first end of the fourth capacitor, and the second end of the fourth capacitor is connected to the main control unit.

7. The LED driving circuit for two-wire programming according to claim 1, characterized in that: The voltage divider circuit comprises: a twelfth resistor and a thirteenth resistor; The first end of the twelfth resistor is connected to the internal auxiliary power supply port, the second end of the twelfth resistor is connected to the first end of the thirteenth resistor and the detection end of the main control unit, and the second end of the thirteenth resistor is grounded.

8. The LED driving circuit for two-wire programming according to claim 1, characterized in that: The first isolation circuit includes: a first diode; the second isolation circuit includes: a second diode; the voltage stabilizing circuit includes: a ninth resistor, a tenth resistor, an eleventh resistor, a reference device, a fifth capacitor and a fourth transistor; The anode of the first diode is connected to the output end of the switch control circuit, the anode of the first diode is connected to the emitter of the fourth transistor and the cathode of the second diode, the anode of the second diode is connected to the internal auxiliary power supply port, the emitter of the fourth transistor is connected to the power supply end of the main control unit, the base of the fourth transistor is connected to the first end of the fifth capacitor, the second end of the fifth capacitor is connected to the second end of the reference device and the second end of the tenth resistor, and the first end of the tenth resistor is connected to the emitter of the fourth transistor; The first end of the ninth resistor is connected to the collector of the fourth transistor, the second end of the ninth resistor is connected to the base of the fourth transistor and the first end of the reference device, the third end of the reference device and the second end of the eleventh resistor are grounded, and the second end of the tenth resistor is connected to the first end of the eleventh resistor.

9. An LED driving power supply, characterized in that: include: An LED driving circuit for two-wire programming as described in any one of claims 1 to 8.

10. An LED driving system, characterized in that: include: A plurality of LED driving power supplies used in parallel, each of the LED driving power supplies comprising an LED driving circuit for two-wire programming as described in any one of claims 1-8.

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