LED load driving circuit and driving chip

Abstract

The application provides a driving circuit and a driving chip for LED loads. The driving circuit comprises a first light adjusting unit, N-1 second light adjusting units and a control module. When the control module receives a light emitting instruction, the corresponding LED lamp group is controlled to be lighted. The first light adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group. When the control module receives M light emitting instructions, the corresponding M LED lamp groups are controlled to be lighted. The first light adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of one of the LED lamp groups and the sampling signal representing the current flowing through the LED lamp group. M-1 second light adjusting units respectively adjust the working voltage drop of the remaining M-1 LED lamp groups. The value range of M is 2-N. The driving circuit can independently adjust the brightness of each LED lamp group during switching light adjustment, thereby realizing the smooth brightness adjustment effect of the LED load during switching light adjustment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LED light source, more particularly, to a driving circuit and driving chip of LED load. BACKGROUND

[0002] In the occasion of shooting, video recording, live broadcast, etc., LED lighting equipment is often needed for light supplement, and the brightness and color temperature of the LED lighting equipment usually need to be adjusted according to the change of the scene. In the prior art, in order to drive the LED lighting equipment to switch and dim, the following two ways are mostly adopted:

[0003] First, a plurality of switching power supplies are set to drive a plurality of LED lamp beads in the LED lighting equipment, so as to realize independent driving of each string of LED lamp beads, and the output of different groups of switching power supplies is controlled to drive different numbers of LED lamp beads to light, so as to realize dimming.

[0004] Second, a group of switching power supplies are set to supply power to a plurality of LED lamp beads, and a power switch tube is connected in series in each string of LED lamp beads, and the on-off of the power switch tube is controlled to control different numbers of LED lamp beads to light, so as to realize dimming.

[0005] However, the first scheme needs to independently set a plurality of switching power supplies, which has the disadvantages of high cost and large size; the second scheme cannot independently adjust each string of LED lamp beads when switching driving different conduction voltage drops of LED lamp beads to light, so that adverse conditions such as flashing or dimming may occur.

[0006] Therefore, the problems of high cost and non-smooth brightness adjustment of the existing driving LED light source switching and dimming scheme need to be solved. SUMMARY

[0007] In order to solve the technical problem of non-smooth brightness adjustment of the LED light source switching and dimming in the prior art, the present application provides a driving circuit and driving chip of LED load, the LED load includes N LED lamp groups arranged in parallel, N LED lamp groups are powered by a switching power supply, the driving circuit drives N LED lamp groups according to N light emitting instructions, N is a positive integer greater than 1, wherein the driving circuit comprises:

[0008] a dimming module including a first dimming unit and N-1 second dimming units, N-1 second dimming units are arranged one by one corresponding to N-1 LED lamp groups;

[0009] The control module controls the corresponding LED lamp group to light up when the control module receives one of the light-emitting instructions, and the first light-adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group.

[0010] The control module controls the corresponding M LED lamp groups to light up when the control module receives M light-emitting instructions, and the first light-adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group with the largest on-voltage drop among the M LED lamp groups and the sampling signal representing the current flowing through the LED lamp group, and M-1 second light-adjusting units respectively adjust the working voltage drop of the remaining M-1 LED lamp groups, where M is a positive integer between 2 and N.

[0011] Further, each second light-adjusting unit adjusts the working voltage drop of an LED lamp group according to the reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group.

[0012] Further, each second light-adjusting unit further comprises a function of controlling the maximum working voltage drop of an LED lamp group according to the preset reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group.

[0013] Further, each LED lamp group comprises a switch tube, and each second light-adjusting unit adjusts the working voltage drop of an LED lamp group by adjusting the driving voltage of the switch tube in the LED lamp group.

[0014] Further, the first light-adjusting unit adjusts the output voltage of the switching power supply by adjusting the duty cycle of the main power tube in the switching power supply.

[0015] Further, when N is greater than 2, the control module comprises a sampling judgment unit that judges the size relationship of the on-voltage drops of the M LED lamp groups to obtain the LED lamp group with the largest on-voltage drop among the M LED lamp groups.

[0016] Preferably, each second light-adjusting unit comprises a third gating circuit connected to the LED lamp group, the control module controls the first branch of the third gating circuit to transmit the control signal in the active state to the LED lamp group, the control signal in the active state controls the switch tube in the LED lamp group to control the LED lamp group to light up, and controls the first light-adjusting unit to adjust the output voltage of the switching power supply according to the reference signal of the LED lamp group and the sampling signal.

[0017] Preferably, the control module controls the second branch of the third gating circuit to be conductive to transmit the output signal of the second dimming unit to the LED lamp set, the output signal of the second dimming unit controls the switch tube in the LED lamp set to be conductive to control the LED lamp set to be lighted, and the second dimming unit adjusts the working voltage drop of the LED lamp set according to the reference signal and the sampling signal of the LED lamp set.

[0018] Preferably, each of the second dimming units comprises a second comparator, the first input end of the second comparator receives the reference signal of the LED lamp set, the second input end receives the sampling signal representing the current flowing through the LED lamp set, and the output end of the second comparator is connected to the third gating circuit.

[0019] Preferably, the second comparator further comprises a third input end receiving a preset reference signal corresponding to the LED lamp set, and the second comparator controls the maximum working voltage drop of the LED lamp set according to the preset reference signal and the sampling signal representing the current flowing through the LED lamp set.

[0020] Preferably, the first dimming unit comprises a first gating circuit and a second gating circuit, one end of the first gating circuit is connected to the control module, the first end of the second gating circuit is connected to the N LED lamp sets, the control module controls one branch of the first gating circuit to be conductive to transmit the reference signal of one LED lamp set, and controls one branch of the second gating circuit to be conductive to transmit the sampling signal of one LED lamp set.

[0021] Preferably, the first dimming unit comprises a first comparator and a PWM controller, the first input end of the first comparator is connected to the other end of the first gating circuit, the second input end of the first comparator is connected to the other end of the second gating circuit, the output end of the first comparator is connected to the PWM controller, and the PWM controller adjusts the duty cycle of the switching power supply.

[0022] In an embodiment, the LED load comprises a first LED lamp set and a second LED lamp set, the conduction voltage drop of the first LED lamp set is greater than that of the second LED lamp set, when the control module receives a first light-emitting instruction, the control module controls the first LED lamp set to be lighted and controls the first dimming unit to adjust the output voltage of the switching power supply according to the first reference signal and the first sampling signal.

[0023] In an embodiment, when the control module receives a second light-emitting instruction, the control module controls the second LED lamp set to be lighted and controls the first dimming unit to adjust the output voltage of the switching power supply according to the second reference signal and the second sampling signal.

[0024] In an embodiment, when the control module receives the first light-emitting instruction and the second light-emitting instruction, the control module controls the first LED lamp group and the second LED lamp group to be lighted up, controls the first light-adjusting unit to adjust the output voltage of the switching power supply according to the first reference signal and the first sampling signal, and controls the second light-adjusting unit to adjust the working voltage drop of the second LED lamp group according to the second reference signal and the second sampling signal.

[0025] A driving circuit of an LED load, the LED load comprising N LED lamp groups arranged in parallel, the N LED lamp groups being powered by a switching power supply, the driving circuit driving the N LED lamp groups according to N light-emitting instructions respectively, N being a positive integer greater than 1, the driving circuit comprising:

[0026] a light-adjusting module comprising a first light-adjusting unit and N second light-adjusting units, the N second light-adjusting units being arranged in one-to-one correspondence with the N LED lamp groups respectively;

[0027] when the control module receives one of the light-emitting instructions, the control module controls a corresponding LED lamp group to be lighted up, and the first light-adjusting unit adjusts the output voltage of the switching power supply according to a reference signal of the LED lamp group and a sampling signal representing a current flowing through the LED lamp group;

[0028] when the control module receives M light-emitting instructions, the control module controls M LED lamp groups to be lighted up, the first light-adjusting unit adjusts the output voltage of the switching power supply according to a reference signal of an LED lamp group with the largest turn-on voltage drop among the M LED lamp groups and a sampling signal representing a current flowing through the LED lamp group, and M-1 second light-adjusting units adjust working voltage drops of the remaining M-1 LED lamp groups respectively, M being a positive integer between 2 and N; wherein,

[0029] the control module comprises a sampling judgment unit, the sampling judgment unit judging the size relationship of the turn-on voltage drops of the M LED lamp groups to obtain the LED lamp group with the largest turn-on voltage drop among the M lamp groups.

[0030] A driving chip of an LED load, the driving chip comprising N instruction receiving pins and N connection pins of external LED lamp groups, the instruction receiving pins receiving light-emitting instructions for driving the LED lamp groups, and the driving chip further integrating the above-described driving circuit.

[0031] Further, the driving chip further comprises N sampling pins, each of the sampling pins being externally connected with a sampling resistor, and a switch tube in the LED lamp group being connected between the sampling pin and the connection pin.

[0032] In summary, the driving circuit proposed in the application can realize brightness adjustment by adjusting the output voltage of the switching power supply when driving a single LED lamp group, and can realize brightness adjustment of each LED lamp group by adjusting the output voltage of the switching power supply and adjusting the working voltage drop of the LED lamp group when driving multiple LED lamp groups. Therefore, the driving circuit proposed in the application can independently adjust the brightness of each LED lamp group during switching dimming, thereby achieving the effect of smooth brightness adjustment during switching dimming of the LED load. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 a framework diagram of the first driving circuit proposed in the application;

[0034] Figure 2 a specific structure diagram of the driving circuit in the first embodiment;

[0035] Figure 3 a specific structure diagram of the driving circuit in the second embodiment;

[0036] Figure 4 a specific structure diagram of the driving circuit in the third embodiment;

[0037] Figure 5 a framework diagram of the second driving circuit proposed in the application;

[0038] Figure 6 a specific structure diagram of the driving circuit in the fourth embodiment;

[0039] Figure 7 an internal structure diagram of the driving chip proposed in the application;

[0040] Figure 8 an external connection structure diagram of the driving chip proposed in the application. DETAILED DESCRIPTION

[0041] Some preferred embodiments of the application will be described in detail below with reference to the accompanying drawings, but the application is not limited thereto.

[0042] Based on the problems of high cost, easy occurrence of bright or dark explosion and other adverse visual effects in the switching dimming process of the LED light source in the prior art, the application proposes a driving circuit for an LED load, as shown in Figure 1 , wherein

[0043] The LED load includes N LED lamp groups arranged in parallel, the LED load composed of the N LED lamp groups arranged in parallel is powered by only one switching power supply, one LED lamp group is controlled to be turned on and dimmed by one light-emitting instruction, the driving circuit drives the N LED lamp groups according to N light-emitting instructions, and N is a positive integer greater than or equal to 2; wherein the driving circuit includes:

[0044] The dimming module is used for adjusting the brightness of the LED lamp group, and comprises a first dimming unit and N-1 second dimming units, wherein the N-1 second dimming units are respectively arranged in one-to-one correspondence with N-1 LED lamp groups, and the remaining one LED lamp group without the second dimming unit is the LED lamp group with the maximum on-voltage drop in the N LED lamp groups;

[0045] The control module receives a light-emitting instruction, controls the lighting of the LED lamp group corresponding to the light-emitting instruction, and controls the dimming module to dim the corresponding LED lamp group; wherein,

[0046] When the control module receives only one light-emitting instruction, the control module controls the lighting of the LED lamp group corresponding to the light-emitting instruction, and controls the first dimming unit to adjust the brightness of the LED lamp group; wherein, the first dimming unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group, to adjust the brightness of the LED lamp group;

[0047] When the control module receives M light-emitting instructions, the control module controls the lighting of the M LED lamp groups corresponding to the M light-emitting instructions, and controls the first dimming unit to adjust the brightness of the LED lamp group with the maximum on-voltage drop in the M LED lamp groups, and controls the M-1 second dimming units to respectively adjust the brightness of the remaining M-1 LED lamp groups in the M LED lamp groups; wherein, the first dimming unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group to be adjusted and the sampling signal representing the current flowing through the LED lamp group to be adjusted, to adjust the brightness of the LED lamp group; the second dimming unit adjusts the brightness of the LED lamp group to be adjusted by adjusting the working voltage drop of the LED lamp group to be adjusted. Wherein, M is an integer value in 2 to N. According to the common knowledge in the art, when the driving circuit controls the lighting of the M LED lamp groups, the output voltage of the switching power supply needs to meet the requirements of the LED lamp group with the maximum on-voltage drop, so as to ensure that the M LED lamp groups are all driven with sufficient voltage to light up. Therefore, it is obvious that the driving circuit proposed in the present application needs to determine the size relationship of the on-voltage drops of the M LED lamp groups in some situations when driving the lighting of the M LED lamp groups. Specifically, when the LED lamp group with the maximum on-voltage drop is not included in the M LED lamp groups, the control module needs to determine the size relationship of the on-voltage drops of the M LED lamp groups, and controls the first dimming unit to adjust the output voltage of the switching power supply according to the reference signal and the sampling signal of the LED lamp group with the maximum on-voltage drop in the M LED lamp groups; when the LED lamp group with the maximum on-voltage drop is included in the M LED lamp groups, the control module does not need to determine the size relationship of the on-voltage drops of the M LED lamp groups, and the control module directly controls the first dimming unit to adjust the output voltage of the switching power supply according to the reference signal and the sampling signal of the LED lamp group with the maximum on-voltage drop.

[0048] Therefore, the driving circuit can independently adjust the brightness of each LED lamp group in the process of switching dimming, so that the adverse visual effects of sudden brightness or sudden darkness caused by excessive or insufficient instantaneous current of a certain LED lamp group do not occur, that is, the effect of smooth brightness adjustment of LED load switching dimming is achieved.

[0049] The driving circuit of the LED load proposed in the present application will be further described below in combination with specific embodiments and drawings.

[0050] Most preferably, in order to simplify the setting and control logic of the driving circuit, the LED load in the first embodiment is composed of only two parallelly arranged first and second LED lamp groups, and it is known that the on-voltage drop of the first LED lamp group is greater than that of the second LED lamp group. With such a setting of the driving circuit, it is not necessary to determine the size relationship of the on-voltage drops of the corresponding multiple LED lamp groups when multiple light-emitting instructions are received, so that the circuit structure and control logic of the driving circuit can be greatly simplified, and the effect of smooth brightness adjustment of LED load switching dimming can also be met. Specifically, as shown in FIG. 1, the driving circuit of the LED load in the first embodiment is composed of a switch power supply 1, a first LED lamp group 2, a second LED lamp group 3, a first switch 4, a second switch 5, a third switch 6, a fourth switch 7, a first resistor 8, a second resistor 9, a third resistor 10, a fourth resistor 11, a fifth resistor 12, a sixth resistor 13, a seventh resistor 14, an eighth resistor 15, a first capacitor 16, a second capacitor 17, a third capacitor 18, a fourth capacitor 19, a fifth capacitor 20, a sixth capacitor 21, a seventh capacitor 22, an eighth capacitor 23, a ninth capacitor 24, a tenth capacitor 25, a first diode 26, a second diode 27, a third diode 28, a fourth diode 29, a fifth diode 30, a sixth diode 31, a seventh diode 32, an eighth diode 33, a ninth diode 34, a tenth diode 35, an eleventh diode 36, a twelfth diode 37, a thirteenth diode 38, a fourteenth diode 39, a fifteenth diode 40, a first transistor 41, a second transistor 42, a third transistor 43, a fourth transistor 44, a first light-emitting instruction input terminal 45, a second light-emitting instruction input terminal 46, a third light-emitting instruction input terminal 47, a fourth light-emitting instruction input terminal 48, a first light-emitting instruction output terminal 49, a second light-emitting instruction output terminal 50, a third light-emitting instruction output terminal 51, a fourth light-emitting instruction output terminal 52, a first voltage input terminal 53, a second voltage input terminal 54, a first current input terminal 55, a second current input terminal 56, a first voltage output terminal 57, a second voltage output terminal 58, a first current output terminal 59, and a second current output terminal 60. Figure 2As shown, the LED load includes two parallel-connected first and second LED lamp groups, with the conduction voltage drop of the first LED lamp group being greater than the conduction voltage drop of the second LED lamp group. The first LED lamp group includes a series-connected LED lamp bead D1, a switch tube Q1, and a sampling resistor SENSE1, while the second LED lamp group includes a series-connected LED lamp bead D2, a switch tube Q2, and a sampling resistor SENSE2. The driver circuit drives the first LED lamp group to illuminate and dim according to a first light-emitting instruction, and drives the second LED lamp group to illuminate and dim according to a second light-emitting instruction. The first dimming unit 101 in the driver circuit 10 includes a first comparator EA1, a first gating circuit 1011, a second gating circuit 1012, and a PWM controller. The second dimming unit 102 includes a second comparator EA2 and a third gating circuit 1021. The control module 103 includes an instruction control unit 1031, a dimming control unit U1, and a dimming control unit U2. One end of the first gating circuit 1011 is connected to the dimming control unit U1 and the dimming control unit U2, and the other end is connected to the non-inverting input of the first comparator EA1. One end of the second gating circuit 1012 is connected between the sampling resistor SENSE1 and the sampling resistor SENSE2, and the other end is connected between the inverting input of the first comparator EA1. The output of the first comparator EA1 is connected to a PWM controller, which adjusts the duty cycle of the main power transistor and the freewheeling transistor in the switching power supply. The first non-inverting input of the second comparator EA2 is connected to the dimming control unit U2, and the inverting input of the second comparator EA2 is connected to the sampling resistor SENSE2. One end of the third gating circuit 1021 is connected to the output of the second comparator EA2, and the other end is connected to the control terminal of the switching transistor Q2.

[0051] When the control module 103 receives the first light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the active state, the second control signal in the inactive state, the first, second and third strobe signals, and the dimming control unit U1 outputs the first reference signal Vref1 according to the first light-emitting instruction. The first control signal in the active state is directly transmitted to the control end of the switch tube Q1 to control the switch tube Q1 to be turned on, thus controlling the first LED lamp set to be lit. At the same time, the first strobe signal controls the first branch of the first gate circuit 1011 to be turned on, the positive input end of the first comparator EA1 is connected to the dimming control unit U1 when the first branch of the first gate circuit 1011 is turned on, the second strobe signal controls the first branch of the second gate circuit 1012 to be turned on, the negative input end of the first comparator EA1 is connected to the sampling resistor SENSE1 when the first branch of the second gate circuit 1012 is turned on, thus the first comparator EA1 outputs the output signal according to the first reference signal Vref1 and the sampling voltage Vsense1, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the first LED lamp set. The third strobe signal controls the first branch of the third gate circuit 1021 to be turned on, and the second control signal in the inactive state is directly transmitted to the control end of the switch tube Q2 when the first branch of the third gate circuit 1021 is turned on, the second control signal in the inactive state controls the switch tube Q2 to be turned off, thus controlling the second LED lamp set to be extinguished.

[0052] When the control module 103 receives the second light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the invalid state, the second control signal in the valid state, the first, second and third gate signals, and the dimming control unit U2 outputs the second reference signal Vref2 according to the second light-emitting instruction. The first control signal in the invalid state is directly sent to the control end of the switch tube Q1 to control the switch tube Q1 to be turned off, thus controlling the first LED lamp set to be extinguished. The third gate signal controls the first branch of the third gate circuit 1021 to be turned on, and when the first branch of the third gate circuit 1021 is turned on, the second control signal in the valid state is directly transmitted to the control end of the switch tube Q2, and the second control signal in the valid state controls the switch tube Q2 to be turned on, thus controlling the second LED lamp set to be lit. At the same time, the first gate signal controls the second branch of the first gate circuit 1011 to be turned on, and when the second branch of the first gate circuit 1011 is turned on, the non-inverting input end of the first comparator EA1 is connected to the dimming control unit U2, the second gate signal controls the second branch of the second gate circuit 1012 to be turned on, and when the second branch of the second gate circuit 1012 is turned on, the inverting input end of the first comparator EA1 is connected to the sampling resistor SENSE2, thus the first comparator EA1 outputs the output signal according to the second reference signal Vref2 and the sampling voltage Vsense2, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the second LED lamp set.

[0053] When the control module 103 receives the first light-emitting instruction and the second light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the active state, the second control signal in the active state, the first gate signal, the second gate signal and the third gate signal, the dimming control unit U1 outputs the first reference signal Vref1 according to the first light-emitting instruction, and the dimming control unit U2 outputs the second reference signal Vref2 according to the second light-emitting instruction. The first control signal in the active state is directly sent to the control end of the switch tube Q1 to control the switch tube Q1 to be turned on, so as to control the first LED lamp set to be lit. At the same time, the first gate signal controls the first branch of the first gate circuit 1011 to be turned on, the positive input end of the first comparator EA1 is connected to the dimming control unit U1 when the first branch of the first gate circuit 1011 is turned on, the second gate signal controls the first branch of the second gate circuit 1012 to be turned on, and the negative input end of the first comparator EA1 is connected to the sampling resistor SENSE1 when the first branch of the second gate circuit 1012 is turned on, so that the first comparator EA1 outputs an output signal according to the first reference signal Vref1 and the sampling voltage Vsense1, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, so as to adjust the brightness of the first LED lamp set. In addition, the third gate signal controls the second branch of the third gate circuit 1021 to be turned on, the second control signal in the active state cannot be directly transmitted to the control end of the switch tube Q2 when the second branch of the third gate circuit 1021 is turned on, but the output end of the second comparator EA2 is connected to the control end of the switch tube Q2, so that the second control signal in the active state is suspended, the output signal of the second comparator EA2 controls the switch tube Q2 to be turned on, so that the second LED lamp set is lit, and the second comparator EA2 adjusts the driving voltage of the switch tube Q2 according to the second reference signal Vref2 and the sampling voltage Vsense2 to adjust the on-off degree of the switch tube Q2, so as to adjust the brightness of the second LED lamp set.

[0054] Further, when the second light-emitting instruction represents that the brightness of the second LED lamp set is high and the drain-source voltage of the switch tube Q2 is large, at this time the switch tube Q2 is linearly turned on, and the switch tube Q2 may be damaged due to high temperature. Therefore, the second positive input end of the second comparator EA2 also receives a preset reference signal, the voltage value represented by the preset reference signal Vref_set is smaller than the voltage value of the second reference signal Vref2, so the second comparator EA2 adjusts the driving voltage of the switch tube Q2 according to the preset reference signal Vref_set and the sampling voltage Vsense2, so as to clamp the maximum working voltage drop of the second LED lamp set at the voltage value corresponding to the preset reference signal Vref_set, thereby avoiding that the working voltage drop of the second LED lamp set is too large.

[0055] In the embodiment, the first light-emitting instruction is a pulse signal representing a certain duty ratio, the brightness of the first LED lamp group is in proportional relationship with the duty ratio represented by the first light-emitting instruction, and the brightness of the first LED lamp group is determined by the sampling resistor SENSE1 and the duty ratio represented by the first light-emitting instruction, and the second light-emitting instruction is the same.

[0056] Therefore, in the embodiment, when only the first LED lamp group or the second LED lamp group is lighted, the driving circuit adjusts the brightness of the first LED lamp group or the second LED lamp group by adjusting the output voltage of the switching power supply; when the first LED lamp group and the second LED lamp group are lighted simultaneously, the driving circuit adjusts the brightness of the first LED lamp group by adjusting the output voltage of the switching power supply, and adjusts the brightness of the second LED lamp group by adjusting the working voltage drop of the second LED lamp group. Therefore, no matter under the control of the switching dimming, the brightness of the first LED lamp group and the second LED lamp group can be controlled independently, so that the smooth switching of the brightness in the switching dimming process is realized. In addition, in the embodiment, the driving circuit only needs to receive two light-emitting instructions to control the switching dimming of the LED load, and does not need to receive more input instructions, which greatly reduces the complexity of the circuit structure. Meanwhile, in the embodiment, since the driving circuit knows that the turn-on voltage drop of one LED lamp group is the largest when receiving the two light-emitting instructions, it is not necessary to determine the size relationship of the turn-on voltage drops of the two LED lamp groups, so the structure design and control logic of the driving circuit in the embodiment are simple.

[0057] Further, in the second embodiment, the structure design and control logic of the driving circuit are more complex than those in the first embodiment, and in some cases, the size relationship of the turn-on voltage drops of multiple LED lamp groups needs to be determined. Specifically, as shown in FIG. 2, the driving circuit 200 further comprises a voltage comparator 202, and the voltage comparator 202 is connected to the first sampling resistor SENSE1 and the second sampling resistor SENSE2. Figure 3As shown, the LED load includes three first, second and third LED lamp groups arranged in parallel, and the first LED lamp group has the largest conduction voltage drop. The first LED lamp group includes LED lamp beads D1, a switch tube Q1 and a sampling resistor SENSE1 arranged in series, the second LED lamp group includes LED lamp beads D2, a switch tube Q2 and a sampling resistor SENSE2 arranged in series, and the third LED lamp group includes LED lamp beads D3, a switch tube Q3 and a sampling resistor SENSE3 arranged in series. The driving circuit drives the first, second and third LED lamp groups to light up and dim according to first, second and third light-emitting instructions, respectively. The driving circuit 10 includes a first dimming unit 101, a second dimming unit 102-1 and a second dimming unit 102-2. The first dimming unit 101 includes a first comparator EA1, a first gating circuit 1011, a second gating circuit 1012 and a PWM controller, the second dimming unit 102-1 includes a second comparator EA2-1 and a third gating circuit 1021-1, the second dimming unit 102-2 includes a second comparator EA2-2 and a third gating circuit 1021-2, and the control module 103 includes an instruction control unit 1031, a sampling judgment unit 1032, a dimming control unit U1, a dimming control unit U2 and a dimming control unit U3. One end of the first gating circuit 1011 is connected to the dimming control units U1, U2 and U3, and the other end is connected to the positive input terminal of the first comparator EA1. One end of the second gating circuit 1012 is connected to the sampling resistors SENSE1, SENSE2 and SENSE3, and the other end is connected to the negative input terminal of the first comparator EA1. The output terminal of the first comparator EA1 is connected to the PWM controller, which adjusts the duty cycle of the main power tube and the freewheeling tube in the switching power supply. The first positive input terminal of the second comparator EA2-1 is connected to the dimming control unit U2, and the negative input terminal is connected to the sampling resistor SENSE2. One end of the third gating circuit 1021-1 is connected to the output terminal of the second comparator EA2-1, and the other end is connected to the control terminal of the switch tube Q2. The first positive input terminal of the second comparator EA2-2 is connected to the dimming control unit U3, and the negative input terminal is connected to the sampling resistor SENSE3. One end of the third gating circuit 1021-2 is connected to the output terminal of the second comparator EA2-2, and the other end is connected to the control terminal of the switch tube Q3. The sampling judgment unit 1032 is connected to the sampling resistors SENSE2 and SENSE3, and the values of the collected sampling voltages Vsense2 and Vsense3 are used to determine the size relationship between the conduction voltage drops of the second and third LED lamp groups, so as to obtain the LED lamp group with the largest conduction voltage drop among the second and third LED lamp groups.

[0058] When the control module 103 receives the first light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the active state, the second control signal in the inactive state, the third control signal in the inactive state, the first gate signal, the second gate signal, the third gate signal-1 and the third gate signal-2, and the dimming control unit U1 outputs the first reference signal Vref1 according to the first light-emitting instruction. The first control signal in the active state is directly transmitted to the control end of the switch tube Q1 to control the switch tube Q1 to be turned on, so that the first LED lamp group is lit. At the same time, the first gate signal controls the first branch of the first gate circuit 1011 to be turned on, and when the first branch of the first gate circuit 1011 is turned on, the non-inverting input end of the first comparator EA1 is connected to the dimming control unit U1, the second gate signal controls the first branch of the second gate circuit 1012 to be turned on, and when the first branch of the second gate circuit 1012 is turned on, the inverting input end of the first comparator EA1 is connected to the sampling resistor SENSE1, so that the first comparator EA1 outputs the output signal according to the first reference signal Vref1 and the sampling voltage Vsense1, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the first LED lamp group. The third gate signal-1 controls the first branch of the third gate circuit 1021-1 to be turned on, and when the first branch of the third gate circuit 1021-1 is turned on, the second control signal in the inactive state is directly transmitted to the control end of the switch tube Q2, and the second control signal in the inactive state controls the switch tube Q2 to be turned off, so that the second LED lamp group is extinguished. The third gate signal-2 controls the first branch of the third gate circuit 1021-2 to be turned on, and when the first branch of the third gate circuit 1021-2 is turned on, the third control signal in the inactive state is directly transmitted to the control end of the switch tube Q3, and the third control signal in the inactive state controls the switch tube Q3 to be turned off, so that the third LED lamp group is extinguished.

[0059] When the control module 103 receives the second light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the invalid state, the second control signal in the valid state, the third control signal in the invalid state, the first gate signal, the second gate signal, the third gate signal-1 and the third gate signal-2, and the dimming control unit U2 outputs the second reference signal Vref2 according to the second light-emitting instruction. The first control signal in the invalid state is directly transmitted to the control end of the switch tube Q1 to control the switch tube Q1 to be off, so the first LED lamp group is extinguished. The third gate signal-1 controls the first branch of the third gate circuit 1021-1 to be conductive, and when the first branch of the third gate circuit 1021-1 is conductive, the second control signal in the valid state is directly transmitted to the control end of the switch tube Q2, and the second control signal in the valid state controls the switch tube Q2 to be conductive, so the second LED lamp group is lit. At the same time, the first gate signal controls the second branch of the first gate circuit 1011 to be conductive, and when the second branch of the first gate circuit 1011 is conductive, the non-inverting input end of the first comparator EA1 is connected to the dimming control unit U2, the second gate signal controls the second branch of the second gate circuit 1012 to be conductive, and when the second branch of the second gate circuit 1012 is conductive, the inverting input end of the first comparator EA1 is connected to the sampling resistor SENSE2, so the first comparator EA1 outputs the output signal according to the second reference signal Vref2 and the sampling voltage Vsense2, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the second LED lamp group. The third gate signal-2 controls the first branch of the third gate circuit 1021-2 to be conductive, and when the first branch of the third gate circuit 1021-2 is conductive, the third control signal in the invalid state is directly transmitted to the control end of the switch tube Q3, and the third control signal in the invalid state controls the switch tube Q3 to be off, so the third LED lamp group is extinguished.

[0060] When the control module 103 receives the third light-emitting instruction, the control process is the same as that when the second light-emitting instruction is received, which will not be repeated here.

[0061] When the control module 103 receives the first light-emitting instruction and the second light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the active state, the second control signal in the active state, the third control signal in the inactive state, the first gate signal, the second gate signal, the third gate signal-1 and the third gate signal-2, the dimming control unit U1 outputs the first reference signal Vref1 according to the first light-emitting instruction, and the dimming control unit U2 outputs the second reference signal Vref2 according to the second light-emitting instruction. The first control signal in the active state is directly transmitted to the control end of the switch tube Q1 to control the switch tube Q1 to be turned on, so that the first LED lamp group is lit. At the same time, the first gate signal controls the first branch of the first gate circuit 1011 to be turned on, and when the first branch of the first gate circuit 1011 is turned on, the non-inverting input end of the first comparator EA1 is connected to the dimming control unit U1, the second gate signal controls the first branch of the second gate circuit 1012 to be turned on, and when the first branch of the second gate circuit 1012 is turned on, the inverting input end of the first comparator EA1 is connected to the sampling resistor SENSE1, so that the first comparator EA1 outputs the output signal according to the first reference signal Vref1 and the sampling voltage Vsense1, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the first LED lamp group. In addition, the third gate signal-1 controls the second branch of the third gate circuit 1021-1 to be turned on, and when the second branch of the third gate circuit 1021-1 is turned on, the second control signal in the active state cannot be directly transmitted to the control end of the switch tube Q2, but the output end of the second comparator EA2-1 is connected to the control end of the switch tube Q2, so that the second control signal in the active state is suspended, and the output signal of the second comparator EA2 controls the switch tube Q2 to be turned on, so that the second LED lamp group is lit, and the second comparator EA2 adjusts the driving voltage of the switch tube Q2 according to the second reference signal Vref2 and the sampling voltage Vsense2 to adjust the on-off degree of the switch tube Q2, thereby adjusting the brightness of the second LED lamp group. The third gate signal-2 controls the first branch of the third gate circuit 1021-2 to be turned on, and when the first branch of the third gate circuit 1021-2 is turned on, the third control signal in the inactive state is directly transmitted to the control end of the switch tube Q3, and the third control signal in the inactive state controls the switch tube Q3 to be turned off, so that the third LED lamp group is extinguished.

[0062] When the control module 103 receives the first light-emitting instruction and the third light-emitting instruction, the control process is the same as that of receiving the first light-emitting instruction and the second light-emitting instruction, which will not be repeated here.

[0063] When the control module 103 receives the second and third lighting instructions, the instruction control unit 1031 outputs the first control signal in an inactive state, the second control signal in an active state, the third control signal in an active state, the first selection signal, the second selection signal, the third selection signal-1, and the third selection signal-2. The dimming control unit U2 outputs the second reference signal Vref2 according to the second lighting instruction, and the dimming control unit U3 outputs the third reference signal Vref3 according to the third lighting instruction. The inactive first control signal is directly transmitted to the control terminal of the switch Q1 to control the switch Q1 to turn off, thereby extinguishing the first LED light group. The third selection signal-1 controls the first branch of the third selection circuit 1021-1 to conduct. When the first branch of the third selection circuit 1021-1 is conducting, the active second control signal is directly transmitted to the control terminal of the switch Q2, and the active second control signal controls the switch Q2 to conduct. At the same time, the first selection signal controls the second branch of the first selection circuit 1011 to be turned on. When the second branch of the first selection circuit 1011 is turned on, the positive input terminal of the first comparator EA1 is connected to the dimming control unit U2. The second selection signal controls the second branch of the second selection circuit 1012 to be turned on. When the second branch of the second selection circuit 1012 is turned on, the inverting input terminal of the first comparator EA1 is connected to the sampling resistor SENSE2. Therefore, the first comparator EA1 outputs an output signal according to the second reference signal Vref2 and the sampling voltage Vsense2. The PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the second LED lamp group. Furthermore, the third selection signal -2 controls the conduction of the second branch of the third selection circuit 1021-2. When the second branch of the third selection circuit 1021-2 is on, the active third control signal cannot be directly transmitted to the control terminal of the switch Q3. However, the output of the second comparator EA2-2 is connected to the control terminal of the switch Q3. Therefore, the active third control signal is suspended, and the output signal of the second comparator EA2-2 controls the conduction of the switch Q3. The second comparator EA2-2 then adjusts the drive voltage of the switch Q3 based on the third reference signal Vref3 and the sampled voltage Vsense3 to adjust the conduction level of the switch Q3, thereby adjusting the brightness of the third LED group. At this point, if the sampling determination unit 1032 detects that both the sampled voltage Vsense2 and the sampled voltage Vsense3 are greater than zero, it indicates that the conduction voltage drop of the second LED group is greater than the conduction voltage drop of the third LED group. Subsequently, the brightness of the second and third LED groups is adjusted according to the aforementioned logic.If the sampling judgment unit 1032 collects the sampling voltage Vsense3 equal to zero, it indicates that the conduction voltage drop of the third LED lamp group is greater than the conduction voltage drop of the second LED lamp group. Thereafter, the control unit needs to switch the control of the first branch of the third gating circuit 1021-2, the third branch of the first gating circuit 1011, the third branch of the second gating circuit 1012, and the second branch of the third gating circuit 1021-1 to be conducted, so as to make the first comparator EA1 output an output signal according to the third reference signal Vref3 and the sampling voltage Vsense3, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1 to adjust the brightness of the third LED lamp group; so as to make the second comparator EA2-1 adjust the driving voltage of the switching transistor Q2 according to the second reference signal Vref2 and the sampling voltage Vsense2 to adjust the conduction degree of the switching transistor Q2, thereby adjusting the brightness of the second LED lamp group.

[0064] When the control module 103 receives the first light-emitting instruction, the second light-emitting instruction and the third light-emitting instruction, the instruction control unit 1031 outputs the first control signal in the active state, the second control signal in the active state, the third control signal in the active state, the first gate signal, the second gate signal, the third gate signal-1 and the third gate signal-2, the dimming control unit U1 outputs the first reference signal Vref1 according to the first light-emitting instruction, the dimming control unit U2 outputs the second reference signal Vref2 according to the second light-emitting instruction, and the dimming control unit U3 outputs the third reference signal Vref3 according to the third light-emitting instruction. The first control signal in the active state is directly transmitted to the control end of the switch tube Q1 to control the switch tube Q1 to be turned on, so that the first LED lamp group is lit. At the same time, the first gate signal controls the first branch of the first gate circuit 1011 to be turned on, and when the first branch of the first gate circuit 1011 is turned on, the non-inverting input end of the first comparator EA1 is connected to the dimming control unit U1, the second gate signal controls the first branch of the second gate circuit 1012 to be turned on, and when the first branch of the second gate circuit 1012 is turned on, the inverting input end of the first comparator EA1 is connected to the sampling resistor SENSE1, so that the first comparator EA1 outputs the output signal according to the first reference signal Vref1 and the sampling voltage Vsense1, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the first LED lamp group. The third gate signal-1 controls the second branch of the third gate circuit 1021-1 to be turned on, and when the second branch of the third gate circuit 1021-1 is turned on, the second control signal in the active state cannot be directly transmitted to the control end of the switch tube Q2, but the output end of the second comparator EA2-1 is connected to the control end of the switch tube Q2, so that the second control signal in the active state is suspended, and the output signal of the second comparator EA2-1 controls the switch tube Q2 to be turned on, so that the second LED lamp group is lit, and the second comparator EA2-1 adjusts the driving voltage of the switch tube Q2 according to the second reference signal Vref2 and the sampling voltage Vsense2 to adjust the on-off degree of the switch tube Q2, thereby adjusting the brightness of the second LED lamp group. The third gate signal-2 controls the second branch of the third gate circuit 1021-2 to be turned on, and when the second branch of the third gate circuit 1021-2 is turned on, the third control signal in the active state cannot be directly transmitted to the control end of the switch tube Q3, but the output end of the second comparator EA2-2 is connected to the control end of the switch tube Q3, so that the third control signal in the active state is suspended, and the output signal of the second comparator EA2-2 controls the switch tube Q3 to be turned on, so that the third LED lamp group is lit, and the second comparator EA2-2 adjusts the driving voltage of the switch tube Q3 according to the third reference signal Vref3 and the sampling voltage Vsense3 to adjust the on-off degree of the switch tube Q3, thereby adjusting the brightness of the third LED lamp group.

[0065] Further, when the second light-emitting instruction represents a high brightness of the second LED lamp group and a large drain-source voltage of the switch tube Q2, or the third light-emitting instruction represents a high brightness of the third LED lamp group and a large drain-source voltage of the switch tube Q3, the switch tube Q2 or the switch tube Q3 is linearly conducted, and the switch tube Q2 or the switch tube Q3 can be damaged due to a high temperature. Therefore, the second positive input terminal of the second comparator EA2-1 further receives a preset reference signal Vref_set1, and the voltage value represented by the preset reference signal Vref_set1 is smaller than the voltage value of the second reference signal Vref2. Therefore, the second comparator EA2-1 adjusts the driving voltage of the switch tube Q2 according to the preset reference signal Vref_set1 and the sampling voltage Vsense2, so as to clamp the maximum working voltage drop of the second LED lamp group at the voltage value corresponding to the preset reference signal Vref_set1, and avoid a large working voltage drop of the second LED lamp group. The second positive input terminal of the second comparator EA2-2 further receives a preset reference signal Vref_set2, and the voltage value represented by the preset reference signal Vref_set2 is smaller than the voltage value of the third reference signal Vref3. Therefore, the second comparator EA2-2 adjusts the driving voltage of the switch tube Q3 according to the preset reference signal Vref_set2 and the sampling voltage Vsense3, so as to clamp the maximum working voltage drop of the third LED lamp group at the voltage value corresponding to the preset reference signal Vref_set2, and avoid a large working voltage drop of the third LED lamp group.

[0066] In the embodiment, the first light-emitting instruction is a pulse signal representing a certain duty ratio, the brightness of the first LED lamp group is in a proportional relationship with the duty ratio represented by the first light-emitting instruction, and the brightness of the first LED lamp group is determined by the sampling resistor SENSE1 and the duty ratio represented by the first light-emitting instruction. The second light-emitting instruction and the third light-emitting instruction are the same.

[0067] Therefore, in the embodiment, the brightness of the first LED lamp group, the second LED lamp group and the third LED lamp group can be independently controlled in the process of switching dimming, so that the smooth switching of brightness in the process of switching dimming is realized. In addition, in the embodiment, the driving circuit only needs to receive three light-emitting instructions to control the switching dimming of the LED load composed of three LED lamp groups, without receiving more input instructions, which greatly reduces the complexity of the circuit structure. At the same time, compared with the first embodiment, in the embodiment, the driving circuit needs to judge the size relationship of the conduction voltage drops of the corresponding multiple LED lamp groups in the situation that multiple light-emitting instructions are received and the multiple light-emitting instructions do not drive the LED lamp group with the maximum conduction voltage drop to be lit, and adaptively adjusts according to the judgment result to make the first dimming unit adjust the output voltage of the switching power supply according to the LED lamp group with the maximum conduction voltage drop in the M LED lamp groups, so that the M LED lamp groups are lit at the same time, so the control logic and structure design of the driving circuit in the embodiment will be more complex.

[0068] Further, in the third embodiment, as Figure 4As shown, the LED load includes N LED lamp groups arranged in parallel, the dimming module includes a first dimming unit and N-1 second dimming units, the N-1 second dimming units are arranged in one-to-one correspondence with the N-1 LED lamp groups respectively, and the LED lamp group with the maximum conduction voltage drop in the N LED lamp groups is not arranged with a second dimming unit. The specific structure of the first dimming unit and the second diming unit is as described in the first embodiment and the second embodiment, the dimming control unit in the control module sets according to the specific number of LED lamp groups, the sampling and judging unit in the control module judges the size relationship of the conduction voltage drops of the plurality of LED lamp groups, and the corresponding driving control is as described in the second embodiment, so that when a single LED lamp group is driven, the output voltage of the switching power supply is adjusted by the first dimming unit to realize the brightness adjustment of the LED lamp group, and when a plurality of LED lamp groups are driven, the output voltage of the switching power supply is adjusted by the first diming unit and the working voltage drop of the LED lamp group is adjusted by the second dimming unit to realize the brightness adjustment of each LED lamp group. At the same time, it should be noted that when the sampling and judging unit receives a plurality of light-emitting instructions and the plurality of light-emitting instructions do not drive the LED lamp group with the maximum conduction voltage drop to be lit and dimmed, the sampling and judging unit needs to judge the size relationship of the conduction voltage drops of the plurality of LED lamp groups driven by the plurality of light-emitting instructions, so that the first dimming unit adjusts the output voltage of the switching power supply according to the reference signal and the sampling signal of the LED lamp group with the maximum conduction voltage drop in the corresponding plurality of LED lamp groups, so that the M LED lamp groups are lit at the same time. If the plurality of light-emitting instructions received by the control module drive the known LED lamp group with the maximum conduction voltage drop to be lit, the sampling and judging unit does not need to judge, and the instruction control unit directly controls the first dimming unit to adjust the output voltage of the switching power supply according to the reference signal and the sampling signal of the LED lamp group with the maximum conduction voltage drop.

[0069] Based on the same idea, the present application also provides a second driving circuit for an LED load, which is specifically as follows. Figure 5As shown, the LED load includes N LED lamp groups arranged in parallel, the dimming module includes a first dimming unit and N second dimming units, and the N second dimming units are arranged in one-to-one correspondence with the N LED lamp groups. When the control module receives only one light-emitting instruction, the control module controls the LED lamp group driven by the light-emitting instruction to be lit up, and controls the first dimming unit to adjust the output voltage of the switching power supply according to the reference signal and the sampling signal of the LED lamp group. When the control module receives M light-emitting instructions, the control module controls M LED lamp groups driven by the M light-emitting instructions to be lit up, and the sampling judgment unit in the control module judges the size relationship of the on-voltage drops of the M LED lamp groups to obtain the LED lamp group with the largest on-voltage drop in the M lamp groups, and then controls the first dimming unit to adjust the output voltage of the switching power supply according to the reference signal and the sampling signal of the LED lamp group with the largest on-voltage drop in the M LED lamp groups, and controls M-1 second dimming units to adjust the working voltage drops of the remaining M-1 LED lamp groups in the M LED lamp groups, and M is a positive integer in 2-N. It should be noted that when the control module receives M light-emitting instructions, the size relationship of the on-voltage drops of the M LED lamp groups driven by the M light-emitting instructions needs to be judged, so that the first dimming unit adjusts the output of the switching power supply according to the reference signal and the sampling signal of the LED lamp group with the largest on-voltage drop in the M LED lamp groups, thereby ensuring that the M LED lamp groups are all driven to light up with sufficient voltage.

[0070] Compared with the first driving circuit proposed above, the second driving circuit is additionally provided with a second dimming unit, so that the second driving circuit does not need to detect in advance the LED lamp group with the largest on-voltage drop in the N LED lamp groups, and the N-1 second dimming modules are connected in one-to-one correspondence with the remaining N-1 LED lamp groups. Therefore, the N second dimming units in the second driving circuit can be connected in one-to-one correspondence with the N LED lamp groups in any way. However, it is inevitable that the control module in the second driving circuit needs to judge the size relationship of the on-voltage drops of the multiple LED lamp groups as long as the control module receives multiple light-emitting instructions, so that the control logic of the second driving circuit is more complex.

[0071] Most preferably, in the fourth embodiment, when the LED load is composed of only two first LED lamp groups and second LED lamp groups arranged in parallel, the control logic and structural design of the second driving circuit in this embodiment are the simplest. Specifically, as shown in Figure 6 Compared with Figure 2 an additional second dimming unit and a sampling judgment unit, and the specific principle and connection are as shown in Figure 2The control module controls the first light adjusting unit to adjust the brightness of the first LED lamp group or the second LED lamp group by adjusting the output voltage of the switching power supply when the control module only receives the first light emitting instruction or the second light emitting instruction. The specific control process is the same as that in the first embodiment, which will not be described here. When the control module receives the first light emitting instruction and the second light emitting instruction, the third selection signal-1 controls the first branch of the third gating circuit 1021-1 to be conductive, and when the first branch of the third gating circuit 1021-1 is conductive, the second control signal in the active state is directly transmitted to the control end of the switching tube Q1, and the second control signal in the active state controls the switching tube Q1 to be conductive. At the same time, the first selection signal controls the first branch of the first gating circuit 1011 to be conductive, and the second selection signal controls the first branch of the second gating circuit 1012 to be conductive, so that the first comparator EA1 outputs an output signal according to the first reference signal Vref1 and the sampling voltage Vsense1, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1, thereby adjusting the brightness of the first LED lamp group. In addition, the third selection signal-2 controls the second branch of the third gating circuit 1021-2 to be conductive, the output signal of the second comparator EA2-2 controls the switching tube Q2 to be conductive, and the second comparator EA2-2 adjusts the driving voltage of the switching tube Q2 according to the second reference signal Vref2 and the sampling voltage Vsense2 to adjust the conduction degree of the switching tube Q2, thereby adjusting the brightness of the second LED lamp group. At this time, if the sampling judgment unit 1032 collects that the sampling voltage Vsense1 and the sampling voltage Vsense2 are both greater than zero, it indicates that the conduction voltage drop of the first LED lamp group is greater than that of the second LED lamp group, and then the brightness of the first LED lamp group and the second LED lamp group is adjusted according to the above logic. If the sampling judgment unit 1032 collects that the sampling voltage Vsense2 is equal to zero, it indicates that the conduction voltage drop of the second LED lamp group is greater than that of the first LED lamp group, and then the control unit needs to switch the control of the first branch of the third gating circuit 1021-2, the second branch of the first gating circuit 1011, the second branch of the second gating circuit 1012, and the second branch of the third gating circuit 1021-1 to be conductive, so that the first comparator EA1 outputs an output signal according to the second reference signal Vref2 and the sampling voltage Vsense2, and the PWM controller adjusts the duty cycle of the switching power supply according to the output signal of the first comparator EA1 to adjust the brightness of the second LED lamp group; so that the second comparator EA2-1 adjusts the driving voltage of the switching tube Q1 according to the second reference signal Vref1 and the sampling voltage Vsense1 to adjust the conduction degree of the switching tube Q1, thereby adjusting the brightness of the first LED lamp group.

[0072] The application further provides a driving chip integrated with the driving circuit, the driving chip is provided with N instruction receiving pins, N connecting pins of lamp beads in the external LED lamp groups, N sampling pins, each sampling pin is externally connected with a sampling resistor, each LED lamp group is connected with a switch tube in series, the switch tube is integrated in the driving chip, and the switch tube is connected between the sampling pin and the connecting pin, the driving circuit is integrated in the driving chip, the N instruction receiving pins are connected with the control module of the driving circuit, and the main power tube Q3 and the freewheeling tube Q4 of the switching power supply for supplying power to the LED load are also integrated in the driving chip.

[0073] As shown in Figure 7 and Figure 8 shown, the driving chip is provided with a first instruction receiving pin DIM1, a second instruction receiving pin DIM2, a first sampling pin SENSE1, a second sampling pin SENSE2, a first connecting pin LED1 and a second connecting pin LED2. The first instruction receiving pin DIM1 and the second instruction receiving pin DIM2 are connected with the instruction control unit 1031, the first instruction receiving pin is connected with the dimming control unit U1, the second instruction receiving pin DIM2 is connected with the dimming control unit U2, one end of the second gating circuit is connected with the first sampling pin SENSE1 and the second sampling pin SENSE2, the first connecting pin LED1 is externally connected with the lamp beads in the first LED lamp group, the switch tube Q1 in the first LED lamp group is connected between the first connecting pin LED1 and the first sampling pin SENSE1, the second connecting pin LED2 is externally connected with the lamp beads in the second LED lamp group, and the switch tube Q2 in the second LED lamp group is connected between the second connecting pin LED2 and the second sampling pin SENSE2. Wherein, the principle of how the driving chip drives the first LED lamp group and the second LED lamp group according to the first light-emitting instruction and the second light-emitting instruction is as described above, and will not be repeated here.

[0074] Therefore, the driving chip can independently adjust the brightness of each LED lamp group during the switching of dimming, and realize smooth switching. At the same time, the driving chip only needs to receive two instruction signals to complete the dimming switching control of the two LED lamp groups, greatly simplifies the program of the driving chip for processing input signals, and reduces the probability of program errors in the driving process.

[0075] The preferred embodiments of the application are described in detail above, but the circuit and beneficial effects of the patent should not be considered to be limited to the above-described disclosed embodiments and the drawings, which can better understand the application, therefore, the above-mentioned disclosed embodiments and the drawings are for better understanding of the application, the protection of the application is not limited to the scope of the disclosure, the replacement and modification of the embodiments of the application by the ordinary skilled in the art are within the protection scope of the application.

Claims

1. A driving circuit for an LED load, the LED load comprising N LED lamp groups arranged in parallel, N LED lamp groups being powered by a switching power supply, the driving circuit driving N LED lamp groups according to N light emitting instructions respectively, N being a positive integer greater than 1, characterized in that, The driving circuit comprises: The light adjusting module comprises a first light adjusting unit and N-1 second light adjusting units, and the N-1 second light adjusting units are arranged in one-to-one correspondence with the N-1 LED lamp groups respectively; When the control module receives one light emitting instruction, the control module controls the corresponding LED lamp group to be lit, and the first light adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group. When the control module receives M light emitting instructions, the control module controls the corresponding M LED lamp groups to be lit, the first light adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group with the largest on-voltage drop in the M LED lamp groups and the sampling signal representing the current flowing through the LED lamp group, and M-1 second light adjusting units adjust the working voltage drop of the remaining M-1 LED lamp groups, wherein M is a positive integer between 2 and N. The first light adjusting unit can switch to control any one of the LED lamp groups to adjust the light, and the second light adjusting unit can switch to control the corresponding LED lamp group to adjust the light or switch to control the corresponding LED lamp group to be extinguished.

2. The drive circuit of claim 1, wherein, Each second light adjusting unit adjusts the working voltage drop of an LED lamp group according to the reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group.

3. The drive circuit of claim 2, wherein, Each second light adjusting unit further comprises a maximum working voltage drop control unit for controlling the maximum working voltage drop of an LED lamp group according to a preset reference signal of the LED lamp group and the sampling signal representing the current flowing through the LED lamp group.

4. The drive circuit according to claim 1 or 2, wherein Each LED lamp group comprises a switch tube, and each second light adjusting unit adjusts the working voltage drop of an LED lamp group by adjusting the driving voltage of the switch tube in the LED lamp group.

5. The drive circuit of claim 1, wherein, The first light adjusting unit adjusts the output voltage of the switching power supply by adjusting the duty cycle of the main power tube in the switching power supply.

6. The drive circuit of claim 1, wherein, When N is greater than 2, the control module comprises a sampling judgment unit for judging the size relationship of the on-voltage drops of the M LED lamp groups to obtain the LED lamp group with the largest on-voltage drop in the M lamp groups.

7. The drive circuit of claim 1, wherein, Each second light adjusting unit comprises a third gating circuit connected to the LED lamp group, the control module controls the first branch of the third gating circuit to transmit an effective state control signal to the LED lamp group, the effective state control signal controls the switch tube in the LED lamp group to be turned on to control the LED lamp group to be lit, and the first light adjusting unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group and the sampling signal.

8. The drive circuit of claim 7, wherein, The control module controls the second branch of the third gating circuit to transmit the output signal of the second light adjusting unit to the LED lamp group, the output signal of the second light adjusting unit controls the switch tube in the LED lamp group to be turned on to control the LED lamp group to be lit, and the second light adjusting unit adjusts the working voltage drop of the LED lamp group according to the reference signal of the LED lamp group and the sampling signal.

9. The drive circuit of claim 7, wherein, Each of the second dimming units comprises a second comparator, a first input end of the second comparator receives a reference signal of the LED lamp group, a second input end of the second comparator receives a sampling signal representing a current flowing through the LED lamp group, and an output end of the second comparator is connected to the third gating circuit.

10. The drive circuit of claim 9, wherein, The second comparator further comprises a third input end receiving a preset reference signal corresponding to the LED lamp group, and the second comparator controls a maximum working voltage drop of the LED lamp group according to the preset reference signal and the sampling signal representing the current flowing through the LED lamp group.

11. The drive circuit of claim 8, wherein, The first dimming unit comprises a first gating circuit and a second gating circuit, one end of the first gating circuit is connected to the control module, and a first end of the second gating circuit is connected to the N LED lamp groups, the control module controls a branch of the first gating circuit to be conductive to transmit a reference signal of an LED lamp group, and controls a branch of the second gating circuit to be conductive to transmit a sampling signal of an LED lamp group.

12. The drive circuit of claim 11, wherein, The first dimming unit comprises a first comparator and a PWM controller, a first input end of the first comparator is connected to the other end of the first gating circuit, a second input end of the first comparator is connected to the other end of the second gating circuit, and an output end of the first comparator is connected to the PWM controller, and the PWM controller adjusts a duty cycle of the switching power supply.

13. The drive circuit of claim 1, wherein, The LED load comprises a first LED lamp group and a second LED lamp group, a turn-on voltage drop of the first LED lamp group is greater than that of the second LED lamp group, when the control module receives a first light-emitting instruction, the control module controls the first LED lamp group to be lit, and controls the first dimming unit to adjust an output voltage of the switching power supply according to a first reference signal and a first sampling signal.

14. The drive circuit of claim 13, wherein, When the control module receives a second light-emitting instruction, the control module controls the second LED lamp group to be lit, and controls the first dimming unit to adjust the output voltage of the switching power supply according to a second reference signal and a second sampling signal.

15. The drive circuit of claim 14, wherein, When the control module receives the first light-emitting instruction and the second light-emitting instruction, the control module controls the first LED lamp group and the second LED lamp group to be lit, controls the first dimming unit to adjust the output voltage of the switching power supply according to the first reference signal and the first sampling signal, and controls the second dimming unit to adjust a working voltage drop of the second LED lamp group according to the second reference signal and the second sampling signal.

16. A driving circuit for an LED load, the LED load comprising N LED lamp groups arranged in parallel, N LED lamp groups being powered by a switching power supply, the driving circuit driving N LED lamp groups according to N light emitting instructions respectively, N being a positive integer greater than 1, characterized in that, The driving circuit comprises: a dimming module comprising a first dimming unit and N second dimming units, the N second dimming units are respectively arranged in one-to-one correspondence with the N LED lamp groups; When the control module receives one of the light-emitting instructions, the control module controls a corresponding LED lamp group to be lit, and the first dimming unit adjusts an output voltage of the switching power supply according to a reference signal of the LED lamp group and a sampling signal representing a current flowing through the LED lamp group; When the control module receives M light-emitting instructions, the control module controls corresponding M LED lamp groups to light up, the first dimming unit adjusts the output voltage of the switching power supply according to the reference signal of the LED lamp group with the maximum conduction voltage drop in the M LED lamp groups and the sampling signal representing the current flowing through the LED lamp group, and M-1 second dimming units respectively adjust the working voltage drop of the remaining M-1 LED lamp groups, M being a positive integer between 2 and N; wherein, The control module comprises a sampling judgment unit which judges the size relationship of the conduction voltage drops of the M LED lamp groups to obtain the LED lamp group with the maximum conduction voltage drop in the M lamp groups, The first dimming unit can switch to control any one LED lamp group to dim, and the second dimming unit can switch to control the corresponding LED lamp group to dim or switch to control the corresponding LED lamp group to turn off.

17. A driving chip of LED load, the driving chip comprising N instruction receiving pins and N connecting pins of external LED lamp groups, the instruction receiving pins receiving light-emitting instructions for driving the LED lamp groups, characterized in that, The driving chip further integrates the driving circuit of any one of claims 1-15.

18. The driver chip of claim 17, wherein, The driving chip further comprises N sampling pins, each of which is connected with a sampling resistor, and the switch tube in the LED lamp group is connected between the sampling pin and the connection pin.

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