TW201349925A - LED driving circuit - Google Patents

Abstract

An LED driving circuit is used for driving an LED module, and includes a bridge rectifier providing a pulsating direct current voltage, an inductor with one end coupled to the bridge rectifier, a power switch with one end connected with the other terminal of the inductor and one end of LED module, a first amplifying circuit which transfers the first current flowing through the power switch to a first voltage , a second amplifying circuit which transfers the second current flowing through the LED module to a second voltage; a reference voltage generating circuit providing a reference voltage, and a control unit, which determines when the first voltage is greater than or equal to the reference voltage, controlling the power switch to turn off and determining the second voltage, and the second voltage is less than or equal to the reference voltage, controlling the power switch to turn on, and determine the first voltage again.

Description

Light-emitting diode driving circuit

The invention relates to a driving circuit, in particular to a light emitting diode driving circuit.

In the context of global energy shortages and environmental awareness, energy conservation and environmental considerations with high luminous efficiency and reduced environmental pollution are important indicators for the development of new generations of green energy-saving lighting. Solid-state light sources have become the revolutionary products of the next generation of lighting because of their high efficiency and no waste pollution from traditional light sources. Among them, the light-emitting diodes have high luminous efficiency, long service life, wide viewing angle, high contrast, and small volume. It is an emerging lighting source that has attracted much attention, such as power saving, non-breaking, no heat radiation, mercury-free pollution and convenient manufacturing.

Since the brightness of the light-emitting diode depends on the forward current flowing through it, the higher the forward current is, the higher the brightness is, but the relative thermal energy is also increased. Therefore, the specifications of the light-emitting diode element are clearly applicable to continuous use. The maximum average current (I _avg ) and the instantaneous current peak (I _peak ); in general, the current peak is greater than the average current, that is, the current peak can make the light-emitting diode component the brightest, but can not be used continuously, and the average current is small. However, the brightness of the light-emitting diode elements can be kept uniform. In order to obtain a stable DC power supply from the AC power source for output to the LED, conventionally, a pulse width modulation controller is used, and the rectifier diode and the filter must be used at the output of the pulse width modulation controller. The capacitor is used to stabilize the DC output, and a large-capacity filter capacitor is needed, so that the circuit volume and component cost cannot be saved. If the purpose of low harmonics and high power is to be achieved, the power factor corrector must be additionally used. Cost, and if the AC power is directly rectified by the bridge rectifier, the resistance of the bridge rectifier is used to limit the current flowing through the LED, and the electro-optic conversion efficiency is low because the resistance thermal energy is large. Waste power in vain.

Therefore, the object of the present invention is to provide a high-efficiency photoelectric conversion with low harmonics and high power factor without providing a power factor corrector and a filter capacitor, and directly using an AC power source as input power. A light-emitting diode driving circuit that effectively reduces circuit volume and manufacturing cost.

In order to achieve the above object, the LED driving circuit of the present invention is configured to drive a light-emitting diode module composed of a plurality of series-parallel light-emitting diodes, the LED driving circuit comprising a bridge rectifier, An inductor, a power switch, a first amplifying circuit, a second amplifying circuit, a switch driving circuit, a reference voltage generating circuit and a control unit.

The bridge rectifier receives an AC power and rectifies it to output a pulsating DC voltage; one end of the inductor is electrically coupled to the bridge rectifier to receive the pulsating DC voltage, and the other end and the LED module One end is electrically coupled in the forward direction; the power switch has a first end, a second end, and a controlled end that determines whether the first end is electrically connected to the second end, and the first end and the other end of the inductor Electrically coupled; the first amplifying circuit is electrically coupled to the second end of the power switch, and correspondingly converts and amplifies a first current flowing through the power switch to a first voltage according to a first amplification ratio; The second amplifying circuit is electrically coupled to the other end of the LED module, and according to one The second magnification correspondingly converts and amplifies a second current flowing through the LED module into a second voltage; the switch driving circuit is electrically coupled to the controlled end of the power switch to control the power switch Turning on or not, when the power switch is turned on, the first current flows through the power switch through the inductor, so that the inductor stores energy, and the first amplifying circuit outputs the first voltage, and when the power switch is not turned on, the inductor Dissolving energy, causing the second current to flow through the light emitting diode module, and the second amplifying circuit outputs the second voltage; the reference voltage generating circuit generates a reference voltage according to the pulsed DC voltage; the control unit controls the Switching the driving circuit and receiving the first voltage, the second voltage and the reference voltage input, the control unit receiving the first voltage, and comparing the first voltage to the reference voltage, controlling the switch driving circuit to be non-conducting a power switch, the second amplifying circuit outputs the second voltage to the control unit, and when the control unit compares the second voltage to be less than the reference voltage, controlling the switch drive The power switch circuit is turned on, so that the first amplifier circuit outputs the first voltage to the control unit, the control unit then again comparing the first voltage and the reference voltage.

Preferably, the LED driving circuit further comprises a step-down transformer with a turns ratio N (N>1) for stepping down an AC mains to generate the AC power, so that the AC power is The voltage is less than the total voltage drop of one of the LED modules.

Preferably, the first amplifying circuit includes a first resistor and a first amplifier, and the first resistor is serially connected to the other end of the power switch, so that the first current flows through the first resistor to obtain a first a voltage drop, and the first amplifier is electrically coupled to the junction of the first resistor and the power switch to receive the first voltage And outputting the first voltage according to the first amplification factor, and outputting the first voltage; the second amplification circuit includes a second resistor and a second amplifier, and the second resistor is connected in series to the LED The other end of the module is configured to pass the second current through the second resistor to obtain a second voltage drop, and the second amplifier is electrically coupled to the junction of the second resistor and the LED module. The second voltage drop is accepted, and the second voltage is amplified according to the second amplification factor to output the second voltage.

Preferably, the reference voltage generating circuit includes a third resistor and a fourth resistor connected in series, wherein the other end of the third resistor is grounded, and the other end of the fourth resistor receives the pulsating DC voltage input to the pulsating DC voltage. Performing a voltage division, and taking a voltage drop across the third resistor from the junction of the third resistor and the fourth resistor as the reference voltage.

Preferably, the continuous current rating of the _LED module is I _{LED, CONT} , and the LED driving circuit sets the continuous current rating to have a specification safety ratio F _DeRate less than 1. Making the first magnification Second magnification .

Preferably, the control unit comprises a 2X1 multiplexer receiving the first voltage and the second voltage, a comparator and a D-type flip-flop, and one end of the comparator is connected to the output of the 2X1 multiplexer. The other end is for inputting the reference voltage, and the output end thereof is connected to the D terminal of the D-type flip-flop; the D-type flip-flop operates according to a first clock signal connected to the clock input end thereof, and The Q end is electrically coupled to the switch driving circuit to control whether the power switch is turned on or not through the switch driving circuit; when the Q end of the D-type flip-flop is logic 1, the The 2X1 multiplexer selects and outputs the first voltage, and when the comparator compares the first voltage to the reference voltage, the comparator continuously outputs a logic 1 to the D-type flip-flop to control the switch driving circuit to be turned on. Power switching, and controlling the 2X1 multiplexer to continuously select and output the first voltage until the comparator compares the first voltage to be greater than or equal to the reference voltage, the comparator outputs logic 0 to the D-type flip-flop, so that Controlling the switch driving circuit not to turn on the power switch, and controlling the 2X1 multiplexer to selectively output the second voltage, and when the comparator compares the second voltage to be greater than the reference voltage, the comparator continuously outputs a logic 0 to the a D-type flip-flop, until the comparator compares the second voltage to be less than or equal to the reference voltage, the comparator outputs a logic 1 to the D-type flip-flop, and simultaneously controls the 2X1 multiplexer to select the output of the first Voltage to the comparator.

Preferably, the control unit further includes a mutual exclusion gate or an OR gate, an input end of the mutual exclusion or gate is connected to the D end of the D-type flip-flop, and the other input terminal is connected to the D-type flip-flop Q terminal, and its output terminal is connected to an input terminal of the OR gate, the first clock signal is connected to the other input terminal of the OR gate, and the output terminal of the OR gate is connected to the clock of the D-type flip-flop device The input terminal causes the D-type flip-flop to operate according to a second clock signal of the OR gate output.

Preferably, the LED driving circuit further includes a DC voltage dividing circuit, and the control unit includes the first, second, third, and fourth totals in addition to the above embodiments. An analog-to-digital converter and a correction module, wherein the DC voltage dividing circuit comprises a filter circuit and a voltage dividing circuit, the filter circuit filters the pulsed DC voltage to output a DC voltage, and the voltage dividing circuit Dividing the DC voltage and outputting a third voltage, the first analog digital converter digitizing the first voltage into a first voltage a second analog-to-digital converter that digitizes the second voltage to a second voltage value, the third analog-to-digital converter digitizing the reference voltage to a reference voltage value, the fourth analog-to-digital converter The three voltages are digitized to a third voltage value, and the calibration module sets a correction value according to a preset standard voltage value, the standard voltage value is divided by the third voltage value, and the reference voltage value is corrected by the correction value. And making the corrected reference voltage value equal to the correction value multiplied by the reference voltage value.

Preferably, the control unit further includes a determining module, the determining module receiving the first voltage value, and controlling the switch driving when determining that the first voltage value is greater than the corrected reference voltage value The circuit does not turn on the power switch; otherwise, the switch driving circuit is controlled to turn on the power switch, and the determining module receives the second voltage value, and determines that the second voltage value is less than or equal to the corrected reference voltage value And controlling the switch driving circuit to turn on the power switch; otherwise, controlling the switch driving circuit to not turn on the power switch.

Furthermore, another LED driving circuit of the present invention is configured to drive a light emitting diode module composed of a plurality of series and parallel light emitting diodes, the LED driving circuit comprising a bridge rectifier, an inductor, A power switch, an amplifying circuit, a switch driving circuit, a reference voltage generating circuit and a control unit.

The bridge rectifier receives an AC power and rectifies it to output a pulsating DC voltage; one end of the inductor is electrically coupled to the bridge rectifier to receive the pulsating DC voltage, and the other end and the LED module One end is electrically coupled in the forward direction, and the other end of the LED module is grounded; the power switch has a first end, a second end, and a first end and the second end are electrically connected a controlled end, the first end is electrically coupled to the other end of the inductor; the amplifying circuit is electrically coupled to the second end of the power switch, and is first passed through the power switch according to a magnification The current is correspondingly converted and amplified into a first voltage; the switch driving circuit is configured to control whether the power switch is turned on or not, and when the power switch is turned on, the first current flows through the power switch through the inductor, so that the inductor stores energy, and The amplifying circuit outputs the first voltage. When the power switch is not turned on, the inductor releases energy, so that a second current flows through the LED module and drives the LED module to emit light; the reference voltage is generated. The circuit generates a reference voltage according to the pulsating DC voltage; the control unit controls the switch driving circuit, and receives the first voltage and the reference voltage input, and includes a timer, when the control unit determines that the first voltage is less than the reference voltage When the switch driving circuit is turned on, the switch driving circuit does not turn on the power switch, and starts the timer to make a predetermined time, and judges When the timer reaches the predetermined time, the driving circuit enabling the switching of the power switch is turned on, and simultaneously disabling the timer to zero, and to receive again comparing the first voltage and the reference voltage.

Preferably, the LED driving circuit further includes a DC voltage dividing circuit, and the control unit further includes three analog digit converters, a correction module and a determining module, and the DC voltage dividing circuit includes a filter circuit and a voltage dividing circuit, the filter circuit filters the pulsating DC voltage to output a DC voltage, the voltage dividing circuit divides the DC voltage and outputs a third voltage, and the analog digital conversion The first voltage, the reference voltage, and the third voltage are respectively digitized into a first voltage value, a reference voltage value, and a third voltage value. The calibration module presets a standard voltage value, and sets a calibration value to the standard. Voltage value Dividing the third voltage value, and correcting the reference voltage value with the correction value, so that the corrected reference voltage value is equal to the correction value multiplied by the reference voltage value; when the determining module receives the first voltage value And determining that the first voltage value is less than the corrected reference voltage value, causing the switch driving circuit to turn on the power switch; otherwise, the switch driving circuit does not turn on the power switch, and starts the timer to make the timing reach the predetermined In time, the switch, the driving circuit turns on the power switch, and disables and resets the timer to receive and compare the first voltage value and the corrected reference voltage value again.

In addition, the present invention further provides a light emitting diode driving circuit for driving a light emitting diode module composed of a plurality of series and parallel light emitting diodes, wherein the light emitting diode driving circuit comprises a bridge rectifier, an inductor, and a A power switch, an amplifying circuit, a switch driving circuit, a reference voltage generating circuit and a control unit.

The bridge rectifier receives an AC power and rectifies it to output a pulsating DC voltage; one end of the inductor is electrically coupled to the bridge rectifier to receive the pulsating DC voltage, and the other end and the LED module One end is electrically coupled in the forward direction; the power switch has a first end, a second end, and a controlled end that determines whether the first end is electrically connected to the second end, and the first end and the other end of the inductor Electrically coupled, the second end is grounded; the amplifying circuit is electrically coupled to the other end of the LED module, and correspondingly converts a second current flowing through the LED module according to a magnification And amplifying into a second voltage; the switch driving circuit is configured to control whether the power switch is turned on or not. When the power switch is turned on, a first current flows through the power switch through the inductor, so that the inductor stores energy when the power switch Non-conducting, the inductor releases energy, causing the second current to flow through the illuminating The diode module drives the light emitting diode module to emit light, and the amplifying circuit outputs the second voltage; the reference voltage generating circuit generates a reference voltage according to the pulsed DC voltage; the control unit controls the switch driving circuit, And receiving the second voltage and reference voltage input, and including a timer, when the control unit determines that the second voltage is less than or equal to the reference voltage, causing the switch driving circuit to turn on the power switch, and start the timer Timing a predetermined time, and determining that the timer reaches the predetermined time, causing the switch driving circuit not to turn on the power switch, simultaneously disabling and zeroing the timer to receive and compare the second voltage and the reference again Voltage.

Preferably, the LED driving circuit further includes a DC voltage dividing circuit, and the control unit further includes three analog digit converters, a correction module and a determining module, and the DC voltage dividing circuit includes a filter circuit and a voltage dividing circuit, the filter circuit filters the pulsating DC voltage to output a DC voltage, the voltage dividing circuit divides the DC voltage and outputs a third voltage, and the analog digital conversion The second voltage, the reference voltage, and the third voltage are respectively digitized into a second voltage value, a reference voltage value, and a third voltage value. The calibration module presets a standard voltage value, and sets a calibration value to the standard. Dividing the voltage value by the third voltage value, and correcting the reference voltage value with the correction value, so that the corrected reference voltage value is equal to the correction value multiplied by the reference voltage value; when the determining module determines the second voltage When the value is less than or equal to the corrected reference voltage value, the switch driver turns on the power switch, and starts the timer, so that when the timing reaches the predetermined time, the switch driver does not turn on the work. Switch, while the timer is disabled and zero, to again receive and compare the second reference voltage value and voltage value of the positive correction.

The utility model has the advantages that the power factor corrector and the filter capacitor are not needed, and the AC power source is directly used as the input power, thereby achieving high-efficiency photoelectric conversion and having low harmonics and high power factors, and effectively reducing circuit volume and manufacturing. The cost does achieve the efficacy and purpose of the present invention.

The foregoing and other objects, features, and advantages of the invention are set forth in the <RTIgt;

As shown in FIG. 1 , the LED driving circuit of the present invention is used to drive a LED module 10 composed of a plurality of LEDs D1 in parallel or at least one LED Dipole D1, the first of which is The preferred embodiment mainly includes a bridge rectifier 21, an inductor L1, a power switch Q1, a first amplifying circuit 22, a second amplifying circuit 23, a switch driving circuit 24, a reference voltage generating circuit 25, and a control unit. 26.

The bridge rectifier 21 receives an AC power input and rectifies it to output a pulsating DC voltage VB.

One end of the inductor L1 is electrically coupled to the bridge rectifier 21 to receive the pulsating DC voltage VB, and the total voltage drop of the LED module 10 is not burned because the inductor L1 can work normally without being burned due to continuous charging and energy storage. _{The LED} needs to be larger than the peak VP of the pulsating DC voltage VB (ie VB, for example, the AC power V _AC is 110V, and the total voltage drop V _{LED of the LED} module 10 is greater than X110, and if the total voltage drop V _{LED of the LED} module 10 is smaller than the peak value VP of the pulsating DC voltage VB, a step-down transformer T1 with a turns ratio N>1 needs to be coupled to the front end of the bridge rectifier 21 The voltage is appropriately reduced by the AC mains, so that the total voltage drop V _{LED of the LED} module 10 can be greater than the peak value VP of the pulsating DC voltage VB.

Preferably, the power switch Q1 is a metal oxide half field effect transistor (MOSFET) switch, and the first end (drain) is electrically coupled to the other end of the inductor L1 and one end of the LED module 10.

The first amplifying circuit 22 is electrically coupled to the second end (drain) of the power switch Q1, and correspondingly converts and amplifies a first current i ₁ flowing through the power switch Q1 into a first voltage according to a first amplification factor A1. V1A, in the embodiment, the first amplifying circuit 22 includes a first resistor R1 and a first amplifier AMP1. One end of the first resistor R1 is connected to the second end (drain) of the power switch Q1, and the other end is grounded to make the first Current i ₁ flows through first resistor R1 to produce a first voltage drop VR1 across first resistor R1. The first amplifier AMP1 is connected to one end of the first resistor R1 connected to the power switch Q1 to obtain a first voltage drop VR1 and amplify it to the first amplification factor A1 to output the first voltage V1A to the control unit 26.

The second amplifying circuit 23 is electrically coupled to the other end of the LED module 10, and correspondingly converts and amplifies a second current i ₂ flowing through the LED module 10 according to a second magnification A2. The second voltage V2A, and the second amplifying circuit 23 includes a second resistor R2 and a second amplifier AMP2. The second resistor R2 is connected to the other end of the LED module 10 at one end, and the other end is grounded to make the second current i. ₂ flows through the second resistor R2 to generate a second voltage drop VR2 on the second resistor R2. The second amplifier AMP2 is connected to one end of the second resistor R2 connected to the LED module 10 to obtain a second voltage drop VR2 and is amplified by the second amplification factor A2 to output the second voltage V2A to the control unit 26. In the present embodiment, the resistance of the second resistor R2 is the same as the first resistor R1.

The reference voltage generating circuit 25 is connected to the control unit 26 and generates a reference voltage VREF_A based on the pulsating DC voltage VB. The reference voltage generating circuit 25 of the embodiment includes a third resistor R3 and a fourth resistor R4 connected in series, wherein the other end of the third resistor R3 is grounded, and the other end of the fourth resistor R4 receives the input of the pulsating DC voltage VB to pulsate DC The voltage VB is divided, and the voltage drop across the third resistor R3 is taken as the reference voltage VREF_A from the junction of the third resistor R3 and the fourth resistor R4 and supplied to the control unit 26.

As shown in FIG. 2, in order to stably drive the LED module 10, the control unit 26 of this embodiment needs to limit the inductor current i _L between an upper limit current i _UP and a lower limit current i _DN , even if The first current i ₁ does not exceed the upper limit current i _UP , and the second current i ₂ does not exceed the lower limit current i _DN , therefore, the first amplification factor A1 must make the first amplifier when the first current i ₁ reaches the upper limit current i _UP a first output voltage V1A of greater than or equal AMP1 Vref_a reference voltage, i.e., a first resistor R1 of the first amplifier AMP1 and a first magnification A1 first current i ₁ flows, generating a reference voltage and a reference voltage generating circuit Vref_a 25 (The third resistor R3 is related to the fourth resistor R4); for the same reason, the second amplification factor A2 must make the second voltage V2A output by the second amplifier AMP2 less than or at least equal to when the second current i ₂ reaches the lower limit current i _DN . The reference voltage VREF_A, that is, the second amplifier R2 of the second amplifier AMP2 and the second resistor R2 through which the second current i ₂ flows, and the reference voltage generating circuit 25 that generates the reference voltage VREF_A (the third resistor R3 and the fourth Resistor R4) related.

In addition, since a continuous current rating of the _LED module 10 is known as I _{LED, CONT} , the rms value of the second current i ₂ flowing through the LED module 10 does not exceed the illuminance. The continuous current rating I _{LED, CONT of the} diode module 10, the rms value of the second current i ₂ set in this embodiment is the continuous current rating I _{LED, and the CONT is} multiplied by a specification less than 1. The ratio F _DeRate , and the first amplification factor A1 of the first amplifier AMP1 is also compared with an upper limit coefficient F _{RIP, UP} , AC power V _AC , and a factor ratio N of the step-down transformer T1, and the LED module 10 The continuous current rating I _{LED, CONT} and the continuous current rating are related to the specification safety ratio F _DeRate , so that the first magnification A1 = And the second amplification factor A2 of the second amplifier AMP2 is further related to a lower limit coefficient F _{RIP, DN} , an alternating current power V _AC , a turns ratio N of the step-down transformer T1, a continuous current rating I _{LED, CONT} and The specification safety ratio F _DeRate is set so that the second magnification A2= . And if the resistance of the second resistor R2 is the same as the first resistor R1, the second magnification .

The switch driving circuit 24 is electrically coupled to the controlled end (gate) of the power switch Q1 for controlling whether the drain and the source of the power switch Q1 are turned on or not. When the power switch Q1 is turned on, the first current i _{1 is} passed through the inductor. L1 flows through the power switch Q1, so that the inductor L1 stores (charges), and the first amplifying circuit 22 outputs the first voltage V1A. When the power switch Q1 is not turned on, the inductor L1 releases (discharges) and generates a second current i _{2 .} The light emitting diode module 10 is caused to flow through the light emitting diode module 10, and the second amplifying circuit 23 outputs the second voltage V2A.

The control unit 26 controls the switch drive circuit 24 and receives the first voltage V1A, the second voltage V2A, and the reference voltage VREF_A input as the control unit When the first voltage V1A is received and the first voltage V1A is greater than the reference voltage VREF_A, the switch driving circuit 24 is controlled to not turn on the power switch Q1, so that the second amplifying circuit 23 outputs the second voltage V2A to the control unit 26 and the reference voltage. VREF_A is compared, and when the control unit 26 determines that the second voltage V2A is less than the reference voltage VREF_A, then the control switch driving circuit 24 turns on the power switch Q1, so that the first amplifying circuit 22 outputs the first voltage V1A to the control unit 26, and the control unit 26 The first voltage V1A and the reference voltage VREF_A are compared again, whereby the LED module 10 is driven to emit light.

Specifically, as shown in FIG. 3, the control unit 26 of the first preferred embodiment of the LED driving circuit of the present invention includes a 2X1 multiplexer 27 that receives the first voltage V1A and the second voltage V2A, and a comparator. 28 and a D-type flip-flop D_FF. One end (negative terminal) of the comparator 28 is connected to the output terminal of the 2X1 multiplexer 27, the other end (positive terminal) is input to the reference voltage VREF_A, and the output terminal thereof is connected to the D terminal of the D-type flip-flop D_FF. The D-type flip-flop D_FF operates according to a first clock signal CLK1 connected to its clock input terminal CLK, and its Q terminal is electrically coupled to a selection input terminal of the switch drive circuit 24 and the 2X1 multiplexer 27 to The power switch Q1 is controlled to be turned on or not through the switch driving circuit 24, and simultaneously controls the 2X1 multiplexer 27 to select the first voltage V1A or the second voltage V2A.

Thereby, when the Q terminal of the D-type flip-flop is logic 1, the 2X1 multiplexer 27 selects to output the first voltage V1A to the comparator 28, and the comparator 28 compares the first voltage V1A to be smaller than the reference voltage VREF_A, and compares The controller 28 outputs a logic 1 to the D-type flip-flop D_FF, so that the Q-terminal output of the D-type flip-flop D_FF outputs a logic 1 to control the switch drive circuit 24 to turn on the power switch Q1, and the inductor L1 continues to store energy, so that the first voltage V1A continues to increase. At the same time, the Q terminal of the D-type flip-flop D_FF controls the 2X1 multiplexer 27 to continuously select and output the first voltage V1A until the comparator 28 compares the first voltage V1A to be greater than or equal to the reference voltage VREF_A, and the comparator 28 outputs a logic 0 to the D-type. The flip-flop D_FF causes the Q terminal of the D-type flip-flop D_FF to output a logic 0 to control the switch drive circuit 24 to not turn on the power switch Q1, and the inductor L1 starts to release the light-emitting diode module 10 and generates a second current i ₂ Flowing through the LED module 10, driving the LED module 10 to emit light; and the Q terminal of the D-type flip-flop D_FF controls the 2X1 multiplexer 27 to select and output the second voltage V2A, at this time due to the second voltage V2A is greater than the reference voltage VREF_A, so when the comparator 28 compares the second voltage V2A is greater than the reference When the voltage VREF_A, the comparator 28 continues to output a logic 0 to the D-type flip-flop, so that the output logic 0 controls the switch drive circuit 24 to continue to not turn on the power switch Q1, and the second voltage V2A is released due to the inductance L1, and the second current i2 Gradually decreasing and decreasing, when the comparator 28 compares the second voltage V2A to be less than or equal to the reference voltage VREF_A, the comparator outputs a logic 1 to the D-type flip-flop D_FF, so that the control switch driving circuit 24 turns on the power switch Q1 again, so that the inductor L1 The energy storage device is again charged, and at the same time, the 2X1 multiplexer 27 is controlled to select the first voltage of the output V1A to the comparator, and the LED circuit 10 is driven to emit light by the reverse operation of the circuit.

Referring to FIG. 4, the control unit 26 of the second preferred embodiment of the LED driving circuit of the present invention includes a mutex or gate XOR and a OR gate OR in addition to the first preferred embodiment. One input of the mutual exclusion or gate XOR is connected to the D terminal of the D-type flip-flop D_FF, and the other input is connected to the Q terminal of the D-type flip-flop D_FF, and its output terminal is connected to an input terminal of the gate OR, and One The clock signal CLK1 (the narrower the clock is, the better) is connected to the other input terminal of the gate OR, and the output terminal of the gate OR is connected to the clock input terminal CLK of the D-type flip-flop D_FF, so that the D-type flip-flop D_FF It operates according to a second clock signal CLK2 of the OR gate OR output (generally a positive edge trigger). Therefore, when the D input end of the D-type flip-flop D_FF and the Q output end are opposite to each other, an additional trigger signal can be generated and input to the clock input terminal CLK of the D-type flip-flop D_FF, so that D The Q terminal output of the type flip-flop D_FF can be synchronized with the D terminal input, and does not need to wait for the next working clock of the first clock CLK1 to be triggered, so that the switch driving circuit 24 can be controlled more instantaneously (in time). The power switch Q1 is not turned on, so that the change of the second current i2 flowing through the LED module 10 does not exceed the control range, and the LED module 10 can be driven more stably.

Referring to FIG. 5 again, the third preferred embodiment of the LED driving circuit of the present invention comprises the above-mentioned bridge rectifier 21, the inductor L1, the power switch Q1, the first amplifying circuit 22, the second amplifying circuit 23, and the switch. In addition to the drive circuit 24, the reference voltage generating circuit 25, the control unit 26, and the transformer T1, a DC voltage dividing circuit 29 electrically connected to the control unit 26 is further included. The DC voltage dividing circuit 29 includes a filter circuit 291 and a voltage dividing circuit 292. The filter circuit 291 filters the pulsating DC voltage VB to output a DC voltage. The voltage dividing circuit 292 includes a fifth resistor R5 connected in series. a sixth resistor R6, wherein the other end of the fifth resistor R5 is grounded, and the other end of the sixth resistor R6 is coupled to the filter circuit 291, which divides the DC voltage outputted by the filter circuit 291 to take the voltage on the fifth resistor R5. The voltage is reduced to a third voltage DC_A and supplied to the control unit 26.

The control unit 26 in this embodiment is a digital signal processor, and the first preferred embodiment includes first, second, third, and fourth four analog digital converters 263-266 and a correction module 267. And a determination module 268. The first analog-to-digital converter 263 digitizes the first voltage V1A into a first voltage value V1, the second analog-bit converter 264 digitizes the second voltage V2A into a second voltage value V2, and the third analog-to-digital converter 265 converts the reference voltage VREF_A is digitally converted to a reference voltage value VREF, and the fourth analog-to-digital converter digitizes the third voltage DC_A into a third voltage value DC. The calibration module (program) 267 receives the reference voltage value VREF and the third voltage value DC respectively outputted by the third and fourth analog-to-digital converters 265, 266, and the calibration module 267 presets a standard DC voltage value DC_STD ( The correction module 267 obtains a correction value=standard DC voltage value DC_STD/third voltage value DC according to the standard DC voltage value DC_STD and the third voltage value DC, and corrects the correction value according to the standard DC voltage value DC_STD and the third voltage value DC. The reference voltage value is such that the corrected reference voltage value VREF_CAL=correction value x reference voltage value VREF, and the corrected reference voltage value VREF_CAL is output to the determination module 268. Thereby, it is possible to prevent the corrected reference voltage value VREF_CAL from being affected by the fluctuation of the pulsating DC voltage VB.

The determining module (program) 268 receives the first voltage value V1 and the second voltage value V2 respectively output by the first and second analog-to-digital converters 263 and 264. When the power switch Q1 is turned on, the determining module 268 reads the first The voltage value V1 is determined whether the first voltage value V1 is greater than or equal to the corrected reference voltage value VREF_CAL. If not, the output control signal S controls the switch driving circuit 24 to continuously turn on the power switch Q1, so that the inductor L1 continues to store energy. , then output The control signal S controls the switch driving circuit 24 to not turn on the power switch Q1, so that the inductor L1 releases the light emitting diode module 10, and drives the light emitting diode module 10 to emit light, and then the determining module 268 reads the second The voltage value V2 is determined whether the second voltage value V2 is less than or equal to the corrected reference voltage value VREF_CAL. If not, the output control signal S controls the switch driving circuit 24 to continue to not conduct the power switch Q1, so that the inductor L1 continues to emit light. The pole body module 10 releases energy. If so, the output control signal S controls the switch drive circuit 24 to turn on the power switch Q1, so that the inductor L1 stores energy again, and reads the first voltage value V1 again to perform the above-mentioned determination operation. The determining module 268 repeatedly determines the first voltage value V1 and the second voltage value V2 and controls the power switch Q1 to operate, so that the inductor L1 reverses the energy storage and the energy release to achieve the purpose of driving the LED module 10 to emit light.

It is worth mentioning that the time for the determination module 268 to complete the determination and output the control signal S to the switch drive circuit 24 is the update period of the control signal S, and the reciprocal of the update period is the update frequency. If the update cycle needs to be changed, only the NOPs (abbreviation No Operation, meaning no operation) command is added to the determination module 268, so that the determination module 268 does not perform any action and delays the output of the control signal S for a period of time. The update cycle is changed, and if a fixed update cycle is required, the determination module 268 is placed in a fixed time (for example, 10 microseconds) to interrupt the subroutine.

Referring to FIG. 6 again, the fourth preferred embodiment of the LED driving circuit of the present invention is identical to most of the circuits of the third embodiment, and the main difference is that the second amplifying circuit 23 and the second embodiment are omitted in this embodiment. The three analog-to-digital converter 264, that is, the control unit 26 receives only the first voltage V1A, the reference voltage VREF_A, and the third voltage DC_A input. In addition, a timer 260 (program) is further disposed in the determining module 268 of the control unit 26. When the power switch Q1 is turned on, the determining module 268 reads the first voltage V1A and determines whether the first voltage V1A is greater than the corrected one. The reference voltage value VREF_CAL, if not, controls the switch drive circuit 24 to continuously turn on the power switch Q1, so that the inductor L1 continues to store energy, and if so, the switch drive circuit 24 is controlled not to conduct the power switch Q1, so that the inductor L1 is illuminating the diode die The group 10 releases energy to drive the light emitting diode to emit light, and at the same time, the timer 260 starts counting, and then determines whether the timer 260 is timed up to a predetermined time, and in the embodiment, according to the measurement in the first embodiment. The second current i _{2 is} decreased to a time empirical value that causes the second voltage value V2 to be less than or equal to the corrected reference voltage value VREF_CAL to set the preset time, but is not limited thereto. Therefore, when the determining module 268 determines that the timer 260 has not been counted for the set time, the control switch driving circuit 24 continues to not conduct the power switch Q1, so that the inductor L1 continues to release the light emitting diode module 10 until the determining module 268 judging that the timer 260 has counted up to the preset time, the timer 260 is stopped, and the switch driving circuit 24 is controlled to turn on the power switch Q1 to cause the inductor L1 to be stored again until the determining module 268 determines the first voltage value V1 again. If the corrected reference voltage value VREF_CAL is greater than or equal to the timer 260, the timer 260 is again re-timed, and the switch driving circuit 24 is controlled to not turn on the power switch Q1, so that the inductor L1 is again released to the LED module 10, thereby repeating The operation allows the inductor L1 to reverse the energy storage and release energy to achieve the purpose of driving the LED module 10 to emit light.

Similarly, as shown in FIG. 7, the fifth preferred embodiment of the LED driving circuit of the present invention is identical to most of the circuits of the third embodiment, and the main difference is that the first amplifying circuit 22 is omitted in this embodiment. And the first analog-to-digital converter 263, that is, the control unit 26 only receives the second voltage V2A, the reference voltage VREF_A and the third voltage DC_A input, and the determination module 268 of the control unit 26 is further provided with a timer 260 (program) At the beginning, the determining module 268 causes the switch driving circuit 24 to turn on the power switch Q1, and causes the timer 260 to start timing, and then determines whether the timer 260 is timed to reach a preset time, and the embodiment can also be based on the measurement of the first embodiment. The first current i _{1 is} raised to a time empirical value that causes the first voltage V1A to be greater than or equal to the corrected reference voltage value VREF_CAL to set the preset time, but is not limited thereto.

Therefore, when the determining module 268 determines that the timer 260 has not been counted for a preset time, the control switch driving circuit 24 continues to turn on the power switch Q1 to continue the energy storage of the inductor L1 until the determining module 268 determines that the timer 260 counts up to the set time. The timer 260 is stopped, and the switch driving circuit 24 is controlled to not turn on the power switch Q1, so that the inductor L1 releases the light emitting diode module 10 to drive the light emitting diode module 10 to emit light, and the determining module 268 Then, it is determined whether the second voltage value V2 is less than the corrected reference voltage value VREF_CAL. If not, the control switch driving circuit 24 continues to not conduct the power switch Q1, so that the inductor L1 continues to release the light emitting diode module 10, and if so, The timer 260 is again re-timed, and the switch driving circuit 24 is controlled to turn on the power switch Q1, so that the inductor L1 is again stored, thereby repeatedly operating, so that the inductor reverses the energy storage and release energy to drive the LED module 10 to emit light. The purpose.

Of course, the control unit 26 can also include the above four embodiments. The operation mode is set to four modes, namely mode 1, mode 2, mode 3 and mode 4, for the user to select the desired driving mode.

In addition, it is worth mentioning that although the above embodiment uses the AC power source V _AC as the driving power of the LED module 10, it can also accept the DC power source, that is, the transformer T1 in the above embodiment. The bridge rectifier circuit 21 is removed, and the DC power source is directly input to the inductor L1, and the DC power source must be smaller than the total voltage drop of the LED module 10. The rest of the circuit operates in the same manner as the above embodiment.

In addition, in the embodiment of FIG. 1 and FIG. 3 to FIG. 7, in order to prevent the rectifying diode (not shown) in the bridge rectifier 21 from being short-circuited at the moment when the power switch Q1 is turned off, the output of the bridge rectifier 21 can be used. The terminal is connected in parallel with a small capacitor C, and its capacitance is selected to avoid bridge rectification short circuit and minimize harmonic distortion, such as 470nF.

In summary, the above embodiment does not need to use a power factor corrector and a filter capacitor, and directly uses an AC power source as an input power, thereby achieving high-efficiency photoelectric conversion and having low harmonics and high power factors, and effectively reducing the circuit. The volume and manufacturing cost do achieve the efficacy and purpose of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

10‧‧‧Lighting diode module

21‧‧‧Bridge rectifier

22‧‧‧First amplification circuit

23‧‧‧Second amplifying circuit

24‧‧‧Switch drive circuit

25‧‧‧reference voltage generation circuit

26‧‧‧Microcontroller

27‧‧‧2X1 multiplexer

28‧‧‧ Comparator

29‧‧‧DC voltage divider circuit

260‧‧‧Timer

263‧‧‧First analog-to-digital converter

264‧‧‧Second analog-to-digital converter

265‧‧‧ Third Analog Digital Converter

266‧‧‧fourth analog-to-digital converter

267‧‧‧ calibration module

268‧‧‧Judgement module

291‧‧‧Filter circuit

292‧‧‧voltage circuit

T1‧‧‧ step-down transformer

C‧‧‧ capacitor

VB‧‧‧pulsed DC voltage

i ₁ ‧‧‧first current

i ₂ ‧‧‧second current

L1‧‧‧Inductance

D1‧‧‧Lighting diode

Q1‧‧‧Power switch

VR1‧‧‧ first pressure drop

VR2‧‧‧ second pressure drop

V1A‧‧‧ first voltage

V2A‧‧‧second voltage

V1‧‧‧ first voltage value

V2‧‧‧ second voltage value

A1‧‧‧first magnification

A2‧‧‧second magnification

AMP1‧‧‧First Amplifier

AMP2‧‧‧second amplifier

R1‧‧‧first resistance

R2‧‧‧second resistance

R3‧‧‧ third resistor

R4‧‧‧fourth resistor

R5‧‧‧ fifth resistor

R6‧‧‧ sixth resistor

VREF_CAL‧‧‧corrected reference voltage value

VREF_A‧‧‧reference voltage

VREF‧‧‧ reference voltage value

DC_A‧‧‧ third voltage

DC‧‧‧ third voltage value

CLK1‧‧‧ first clock signal

CLK2‧‧‧ second clock signal

iL‧‧‧Inductor Current

1 is a schematic diagram of a main circuit of a first preferred embodiment of a light-emitting diode driving circuit of the present invention; FIG. 2 is a range of an upper limit current i _UP and a lower limit current i _DN of the inductor current i _L according to the first embodiment of the present invention; 3 is a detailed circuit diagram of a control unit according to a first embodiment of the present invention; FIG. 4 is a schematic diagram of a main circuit of a second preferred embodiment of the LED driving circuit of the present invention, wherein a detailed circuit diagram of the control unit is shown; 5 is a main circuit diagram of a third preferred embodiment of the LED driving circuit of the present invention, wherein a detailed circuit diagram of the control unit is shown; and FIG. 6 is a main embodiment of the fourth preferred embodiment of the LED driving circuit of the present invention. A schematic circuit diagram showing a detailed circuit diagram of a control unit; and FIG. 7 is a schematic diagram of a main circuit of a fifth preferred embodiment of the LED driving circuit of the present invention, in which a detailed circuit diagram of the control unit is shown.

10‧‧‧Lighting diode module

21‧‧‧Bridge rectifier

22‧‧‧First amplification circuit

23‧‧‧Second amplifying circuit

24‧‧‧Switch drive circuit

25‧‧‧reference voltage generation circuit

26‧‧‧Control unit

T1‧‧‧ step-down transformer

VB‧‧‧pulsed DC voltage

i ₁ ‧‧‧first current

i ₂ ‧‧‧second current

L1‧‧‧Inductance

D1‧‧‧Lighting diode

Q1‧‧‧Power switch

VR1‧‧‧ first pressure drop

VR2‧‧‧ second pressure drop

V1A‧‧‧ first voltage

V2A‧‧‧second voltage

A1‧‧‧first magnification

A2‧‧‧second magnification

AMP1‧‧‧First Amplifier

AMP2‧‧‧second amplifier

R1‧‧‧first resistance

R2‧‧‧second resistance

R3‧‧‧ third resistor

R4‧‧‧fourth resistor

VREF_A‧‧‧reference voltage

C‧‧‧ capacitor

iL‧‧‧Inductor Current

Claims (13)

A light-emitting diode driving circuit for driving a light-emitting diode module composed of a plurality of series-parallel light-emitting diodes, the light-emitting diode driving circuit comprising: a bridge rectifier, receiving an alternating current power and Rectifying to output a pulsating DC voltage; an inductor, one end is electrically coupled to the bridge rectifier to receive the pulsating DC voltage, and the other end is electrically coupled to one end of the LED module; a power switch, Having a first end, a second end, and a controlled end that determines whether the first end is electrically connected to the second end, the first end is electrically coupled to the other end of the inductor; a first amplifying circuit, Electrically coupled to the second end of the power switch, and correspondingly converting and amplifying a first current flowing through the power switch to a first voltage according to a first magnification; a second amplifying circuit, and the light emitting diode The other end of the body module is electrically coupled in a forward direction, and correspondingly converts and amplifies a second current flowing through the light emitting diode module into a second voltage according to a second magnification; a switch driving circuit, and the The power switch The first end is electrically coupled to control whether the power switch is turned on or not. When the power switch is turned on, the first current flows through the power switch through the inductor, so that the inductor stores energy, and the first amplifying circuit outputs the first voltage. When the power switch is not turned on, the inductor releases energy, so that the second current flows through the light emitting diode module, and the second amplifying circuit outputs the second voltage; a reference voltage generating circuit according to the pulsed direct current Voltage produces one And a control unit that controls the switch drive circuit and receives the first voltage, the second voltage, and the reference voltage input, and the control unit receives the first voltage and compares the first voltage to be greater than the reference voltage And controlling the switch driving circuit to not turn on the power switch, so that the second amplifying circuit outputs the second voltage to the control unit, and when the control unit compares the second voltage to be less than the reference voltage, controlling the switch driving circuit The power switch is turned on to cause the first amplifying circuit to output the first voltage to the control unit, and the control unit compares the first voltage and the reference voltage again. The LED driving circuit according to Item 1 of the patent application scope further includes a step-down transformer with a turns ratio N (N>1) for stepping down an AC mains to generate the AC power. The voltage of the alternating current power is less than a total voltage drop of the one of the light emitting diode modules. The illuminating diode driving circuit of the second aspect of the invention, wherein the first amplifying circuit comprises a first resistor and a first amplifier, the first resistor is serially connected to the other end of the power switch, so that the a first current flows through the first resistor to obtain a first voltage drop, and the first amplifier is electrically coupled to the junction of the first resistor and the power switch to receive the first voltage drop, and according to the first Amplifying the first voltage drop to output the first voltage; the second amplifying circuit includes a second resistor and a second amplifier, the second resistor is serially connected to the other end of the LED module, so that The second current flows through the second resistor to obtain a second voltage drop, and the second amplifier is electrically coupled to the junction of the second resistor and the LED module to receive the second voltage drop. And amplifying the second voltage drop according to the second magnification to output the second power Pressure. The illuminating diode driving circuit of claim 3, wherein the reference voltage generating circuit comprises a third resistor and a fourth resistor connected in series, wherein the other end of the third resistor is grounded, and the fourth resistor is further The pulsating DC voltage input is received at one end to divide the pulsating DC voltage, and the voltage drop across the third resistor is taken as the reference voltage from the junction of the third resistor and the fourth resistor. According to the light-emitting diode driving circuit of claim 4, wherein the continuous current rating of the _LED module is I _{LED, CONT} , and the LED driving circuit sets the continuous current The rating has a specification safety ratio F _{DeRate of} less than 1, such that the first magnification Second magnification . The illuminating diode driving circuit of claim 5, wherein the control unit comprises a 2X1 multiplexer receiving the first voltage and the second voltage, a comparator and a D-type flip-flop, One end of the comparator is connected to the output end of the 2X1 multiplexer, the other end is for the reference voltage input, and the output end thereof is connected to the D end of the D-type flip-flop; the D-type flip-flop is connected according to a The first clock signal of the clock input terminal acts, and the Q end thereof is electrically coupled to the switch driving circuit to control whether the power switch is turned on or not through the switch driving circuit; when the Q end of the D-type flip-flop When it is logic 1, the 2X1 multiplexer selects to output the first voltage, and when the comparator compares the first voltage to be less than the reference voltage, the comparator continuously outputs logic 1 to the D-type flip-flop to control The switch drive circuit turns on the power switch and controls The 2X1 multiplexer continuously selects and outputs the first voltage until the comparator compares the first voltage to be greater than or equal to the reference voltage, and the comparator outputs a logic 0 to the D-type flip-flop to control the switch driving circuit. The power switch is not turned on, and the 2X1 multiplexer is controlled to selectively output the second voltage, and when the comparator compares the second voltage to be greater than the reference voltage, the comparator continuously outputs a logic 0 to the D-type flip-flop Until the comparator compares the second voltage to be less than or equal to the reference voltage, the comparator outputs a logic 1 to the D-type flip-flop, and simultaneously controls the 2X1 multiplexer to select and output the first voltage to the comparator . The illuminating diode driving circuit of claim 6, wherein the control unit further comprises a mutual repulsion or a gate, and an input of the repulsion or gate is connected to the D-type flip-flop D terminal, another input terminal is connected to the Q terminal of the D-type flip-flop, and an output terminal thereof is connected to an input terminal of the OR gate, and the first clock signal is connected to another input terminal of the OR gate, and the The output of the gate is connected to the clock input of the D-type flip-flop, so that the D-type flip-flop operates according to a second clock signal output by the OR gate. According to claim 5, the LED driving circuit further includes a DC voltage dividing circuit, and the control unit includes first, second, third, and fourth four analog digital converters. a calibration module, wherein the DC voltage dividing circuit comprises a filter circuit and a voltage dividing circuit, the filter circuit filters the pulsed DC voltage to output a DC voltage, and the voltage dividing circuit divides the DC voltage Pressing and outputting a third voltage, the first analog-to-digital converter digitizing the first voltage into a first voltage value, and the second analog-to-digital converter digitizing the second voltage into a second voltage value, the first Three types The reference voltage is digitized into a reference voltage value by a digital converter, and the fourth analog digital converter digitizes the third voltage into a third voltage value, and the calibration module sets a first standard voltage value according to a predetermined standard voltage value. The correction value is the standard voltage value divided by the third voltage value, and the reference voltage value is corrected by the correction value such that the corrected reference voltage value is equal to the correction value multiplied by the reference voltage value. According to the light-emitting diode driving circuit of claim 8, wherein the control unit further includes a determining module, the determining module receives the first voltage value, and determines that the first voltage value is greater than the When the corrected reference voltage value is controlled, the switch driving circuit is controlled not to conduct the power switch; otherwise, the switch driving circuit is controlled to turn on the power switch, and the determining module receives the second voltage value, and determines the first When the two voltage values are less than or equal to the corrected reference voltage value, the switch driving circuit is controlled to turn on the power switch; otherwise, the switch driving circuit is controlled not to turn on the power switch. A light-emitting diode driving circuit for driving a light-emitting diode module composed of a plurality of series-parallel light-emitting diodes, the light-emitting diode driving circuit comprising: a bridge rectifier, receiving an alternating current power and performing the same Rectifying to output a pulsating DC voltage; one end of the inductor is electrically coupled to the bridge rectifier to receive the pulsating DC voltage, and the other end is electrically coupled to one end of the LED module, and the LED is electrically coupled The other end of the body module is grounded; a power switch has a first end, a second end, and a controlled end that determines whether the first end and the second end are conductive or not, the first end and the inductor The other end is electrically coupled; an amplifying circuit is electrically coupled to the second end of the power switch, and correspondingly converts and amplifies a first current flowing through the power switch to a first voltage according to a magnification; a circuit for controlling whether the power switch is turned on or not. When the power switch is turned on, the first current flows through the power switch through the inductor to cause the inductor to store energy, and the amplifying circuit outputs the first voltage when the power The switch is non-conducting, and the inductor releases energy, so that a second current flows through the LED module and drives the LED module to emit light; a reference voltage generating circuit generates a reference voltage according to the pulsed DC voltage; And a control unit that controls the switch driving circuit and receives the first voltage and the reference voltage input, and includes a timer. When the control unit determines that the first voltage is less than the reference voltage, the switch driving circuit is turned on. Power switch, otherwise the switch drive circuit does not turn on the power switch, and starts the timer to make a predetermined time, and judges that the timer reaches the preset When the time, the driving circuit enabling the switching of the power switch is turned on, and simultaneously disabling the timer to zero, and to receive again comparing the first voltage and the reference voltage. The LED driving circuit of claim 10 further includes a DC voltage dividing circuit, and the control unit further includes three analog digit converters, a correction module and a determining module. The DC voltage dividing circuit comprises a filter circuit and a voltage dividing circuit, the filter circuit filters the pulsed DC voltage to output a DC voltage, and the voltage dividing circuit applies the DC voltage Dividing and outputting a third voltage, the analog digital converter respectively digitizing the first voltage, the reference voltage, and the third voltage into a first voltage value, a reference voltage value, and a third voltage value, the calibration module Presetting a standard voltage value, and setting a correction value to divide the standard voltage value by the third voltage value, and correcting the reference voltage value with the correction value, so that the corrected reference voltage value is equal to the correction value multiplied by The reference voltage value; when the determining module receives the first voltage value and determines that the first voltage value is less than the corrected reference voltage value, causing the switch driving circuit to turn on the power switch, otherwise the switch is driven The circuit does not turn on the power switch, and activates the timer to cause the switch drive circuit to turn on the power switch when the timing reaches the predetermined time, and disables and resets the timer to receive and compare the first voltage value again. And the corrected reference voltage value. A light-emitting diode driving circuit for driving a light-emitting diode module composed of a plurality of series-parallel light-emitting diodes, the light-emitting diode driving circuit comprising: a bridge rectifier, receiving an alternating current power and performing the same Rectifying to output a pulsating DC voltage; an inductor, one end is electrically coupled to the bridge rectifier to receive the pulsating DC voltage, and the other end is electrically coupled to one end of the LED module; a power switch having a first end, a second end, and a controlled end that determines whether the first end is electrically connected to the second end, the first end is electrically coupled to the other end of the inductor, and the second end is grounded; An amplifying circuit is electrically coupled to the other end of the LED module, and a second current flowing through the LED module according to a magnification Correspondingly converting and amplifying into a second voltage; a switch driving circuit for controlling whether the power switch is turned on or not, when the power switch is turned on, a first current flows through the power switch through the inductor, so that the inductor stores energy, when The power switch is non-conducting, the inductor releases energy, the second current flows through the LED module and drives the LED module to emit light, and the amplifying circuit outputs the second voltage; a reference voltage is generated a circuit that generates a reference voltage according to the pulsating DC voltage; and a control unit that controls the switch drive circuit and receives the second voltage and the reference voltage input, and includes a timer, when the control unit determines that the second voltage is less than Or equal to the reference voltage, causing the switch driving circuit to turn on the power switch, and starting the timer to make a predetermined time, and determining that the timer reaches the predetermined time, the switch driving circuit does not turn on the power switch. At the same time, the timer is disabled and reset to zero to receive and compare the second voltage with the reference voltage. The illuminating diode driving circuit according to claim 12, further comprising a DC voltage dividing circuit, wherein the control unit further comprises three analog digit converters, a correction module and a judging module, The DC voltage dividing circuit comprises a filter circuit and a voltage dividing circuit, the filter circuit filters the pulsed DC voltage to output a DC voltage, and the voltage dividing circuit divides the DC voltage and outputs a third voltage The analog digital converter respectively digitizes the second voltage, the reference voltage, and the third voltage into a second voltage value, a reference voltage value, and a third voltage value, and the calibration module presets a standard voltage value and sets A correction value is the standard voltage value divided by the third voltage value, And correcting the reference voltage value with the correction value, so that the corrected reference voltage value is equal to the correction value multiplied by the reference voltage value; and when the determining module determines that the second voltage value is less than or equal to the corrected reference voltage And when the value is turned on, the switch driver turns on the power switch, and starts the timer, so that when the timing reaches the predetermined time, the switch driver does not turn on the power switch, and disables and resets the timer to receive the timer again. Comparing the second voltage value with the corrected reference voltage value.