LED constant-current driving chip and lighting device

Abstract

The invention relates to the technical field of LED lighting, and discloses an LED constant-current driving chip and a lighting device, the LED constant-current driving chip comprises a comparator CMP, a pulse generation unit, an adder, a first current control unit and a second current control unit, and the lighting device comprises an LED constant-current driving chip, a rectification unit, an energy storage capacitor CAP and a load LED unit. In actual use, the lighting device can perform reverse compensation on CAP charging current to generate peak current without using a resistor to perform bus voltage detection, so that when a plurality of chips are connected in parallel, the detected bus voltage does not need to be transmitted to each chip by using a jumper resistor; therefore, the application cost when a plurality of chips are connected in parallel in the lighting device is saved, the creepage distance between the negative end of the energy storage capacitor CAP and other nodes is increased due to the reduction of the jumper resistance, and the reliability of the lighting device is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of LED lighting, and in particular to an LED constant current drive chip and a lighting device. Background Art

[0002] In LED drive circuits, linear constant current drive control chips (hereinafter referred to as chips) are often used to ensure that the current flowing through the LED or load is constant. The circuit of a single chip is as follows: Figure 1 shown.

[0003] exist Figure 1 In order to reduce the chip area, the internal circuit of the chip generally includes current control module 1, current control module 2, high voltage power supply module and reference module. In addition, the pins of the chip include charging current input pin DRC, load current input pin DRN, first output pin CSC, second output pin CSN and feedforward signal input pin DET;

[0004] The DRC pin is connected to the negative end of the energy storage capacitor CAP, and the CSC pin is connected to the sampling resistor R CSC One end, resistor R CSC The other end is grounded to adjust the current flowing through the energy storage capacitor CAP;

[0005] Pin DRN is connected to the negative terminal of the load LED, and pin CSN is connected to the resistor R CSN One end, resistor R CSN The other end is grounded to determine the current size of the load.

[0006] When the absolute value of the input voltage VIN(θ) |VIN(θ)| is greater than the voltage across the energy storage capacitor CAP (hereinafter referred to as VCAP), the bus voltage VBUS powers the LED, and the negative end of the LED, i.e., the chip pin DRN, also powers the chip (theoretically, the LED current is equal to the chip power supply current plus the current controlled by the current control module 2, but since the former accounts for less than 0.5% of the latter, the LED current ignores the chip power supply current). At the same time, the bus voltage VBUS can charge the energy storage capacitor CAP, and the charging current is controlled by the current control module 1.

[0007] When |VIN(θ)| is less than VCAP, the energy storage capacitor CAP in turn provides power to the LED, that is, the energy storage capacitor CAP discharges to provide LED and chip operation. The current of the energy storage capacitor CAP flows out from the bus, passes through the MOS tube Q1 from the ground end of the chip and returns to the negative end of the energy storage capacitor CAP.

[0008] When |VIN(θ)| is greater than VCAP again, the bus voltage VBUS supplies power to the LED and chip and charges the energy storage capacitor CAP. Obviously, the input current is the sum of the LED current and the charging current of CAP when |VIN(θ)| is greater than VCAP.

[0009] At present, in order to meet the requirement that the input current of the power grid (hereinafter referred to as input current) reaches the maximum before the 65-degree phase of the input voltage, the chip introduces the VBUS reverse compensation charging current. The bus voltage is divided by resistors R1 and R2 and connected to pin DET. The voltage of pin DET is subtracted from the reference voltage and transmitted to the positive input terminal of the operational amplifier in the current control module. Therefore, the current of the energy storage capacitor CAP will decrease as the bus voltage VBUS increases when the voltage is charged, that is, the bus voltage is superimposed on the charging current as a reverse compensation signal. The role of the voltage-dividing capacitor C1 is to delay this reverse compensation appropriately relative to the bus voltage VBUS, so that the compensation of the rising edge of the bus voltage VBUS is faster than the compensation of the falling edge.

[0010] The driving power of a single chip is between 5W and 12W. For some larger applications, multiple chips are often required to be used in parallel to share the power consumption. The circuit diagram of multiple chips in parallel is shown below. Figure 2 In addition, considering the heat dissipation effect, the components of the entire circuit (except the input power supply) are often soldered on the same side of the single-sided copper-clad aluminum substrate by SMD soldering. Figure 3 shown.

[0011] for Figure 3 The structure uses the detection of bus voltage VBUS to reversely compensate the charging circuit, which inevitably leads to the connection of some circuits through chip resistors as jumpers when multiple chips are used in parallel. Figure 3 The jumper resistance in Figure 2 The arc wire part. However, the use of jumper resistors has the following problems:

[0012] First, the manufacturing cost is increased. Second, the jumper resistor pin body and the pad reduce the distance from the high-voltage node, reducing the long-term reliability of the product and the creepage distance between nodes when surge voltage exists. Summary of the invention

[0013] In view of the shortcomings of the background technology, the present invention provides an LED constant current driver chip and a lighting device. The technical problem to be solved is that the existing LED constant current driver chip has the problem of high cost and poor reliability when used in parallel because it needs to use chip resistors.

[0014] To solve the above technical problems, in a first aspect, the present invention provides the following technical solutions: an LED constant current driving chip, comprising a comparator CMP, a pulse generating unit, an adder, a first current control unit and a second current control unit;

[0015] The positive input terminal of the comparator CMP is electrically connected to the input terminal of the first current control unit, and the negative input terminal of the comparator CMP is used to input the first reference voltage;

[0016] The output end of the comparator CMP is electrically connected to the pulse generating unit, and the pulse generating unit inputs a pulse signal to an input end of the adder after receiving a trigger signal that changes from a low level to a high level, and the other input end of the adder is used for a second reference voltage, and the output end of the adder is electrically connected to the control end of the first current control unit;

[0017] The control end of the second current control unit is used to access the second reference voltage, and the input end of the second current control unit is used to connect to an external load.

[0018] In a second aspect, the present invention provides another structure of an LED constant current driver chip, including a comparator CMP, a pulse generating unit, an adder, a first current control unit and a second current control unit;

[0019] The positive input terminal of the comparator CMP is electrically connected to the output terminal of the first current control unit, and the negative input terminal of the comparator CMP is used to input the first reference voltage;

[0020] The output end of the comparator CMP is electrically connected to the pulse generating unit, and the pulse generating unit inputs a pulse signal to an input end of the adder after receiving a trigger signal that changes from a low level to a high level, and the other input end of the adder is used for a second reference voltage, and the output end of the adder is electrically connected to the control end of the first current control unit;

[0021] The control end of the second current control unit is used to access the second reference voltage, and the input end of the second current control unit is used to connect to an external load.

[0022] In a certain embodiment, the present invention also includes a high-voltage power supply unit and a reference unit, wherein the high-voltage power supply unit is electrically connected to the input end of the second current control unit, and the reference unit is electrically connected to the output end of the high-voltage power supply unit, and the first reference voltage and the second reference voltage are generated based on the voltage output by the high-voltage power supply unit.

[0023] In a certain embodiment, the first current control unit includes an operational amplifier EA1 and a MOS tube Q1, the positive electrode of the operational amplifier EA1 is the control end of the first current control unit, the negative electrode of the operational amplifier EA1 is electrically connected to the source of the MOS tube Q1, the source of the MOS tube Q1 is the output end of the first current control unit, the output end of the operational amplifier EA1 is electrically connected to the gate of the MOS tube Q1, and the drain of the MOS tube Q1 is the input end of the first current control unit.

[0024] In a certain embodiment, the second current control unit includes an operational amplifier EA2 and a MOS tube Q2, the positive electrode of the operational amplifier EA2 is the control end of the second current control unit, the negative electrode of the operational amplifier EA2 is electrically connected to the source of the MOS tube Q2, the source of the MOS tube Q2 is the output end of the second current control unit, the output end of the operational amplifier EA2 is electrically connected to the gate of the MOS tube Q2, and the drain of the MOS tube Q2 is the input end of the second current control unit.

[0025] In a certain embodiment, the present invention further comprises a chip body, and the comparator CMP, the pulse generating unit, the adder, the first current control unit, the second current control unit, the high voltage power supply unit and the reference unit are all arranged on the chip body;

[0026] The chip body is also provided with pins DRC, DRN, CSC, CSN and a ground pin. The input end of the first current control unit is electrically connected to the pin DRC, the input end of the second current control unit is electrically connected to the pin DRN, the output end of the first current control unit is electrically connected to the pin CSC, the output end of the second current control unit is electrically connected to the pin CSN, and the ground pin is used to be electrically connected to the ground terminal in the circuit.

[0027] In a certain embodiment, the first current control unit and the second current control unit are distributed left and right on the chip body, the pin DRC and the ground pin are located on the upper side of the chip body, and the pin CSC, pin CSN and pin DRN are located on the lower side of the chip body.

[0028] In a second aspect, the present invention provides a lighting device, comprising at least one LED constant current driver chip as described above, and further comprising a rectifier unit, an energy storage capacitor CAP and a load LED unit, wherein the load LED unit comprises N LED lamps, N is a positive integer, and when N is greater than 1, all the LED lamps are connected in series in sequence;

[0029] The output end of the rectifier unit is electrically connected to the positive electrode of the energy storage capacitor CAP and the positive electrode of the first-end LED lamp respectively, the negative electrode of the energy storage capacitor CAP is electrically connected to the pin DRC of each chip, and the negative electrode of the terminal LED lamp is electrically connected to the pin DRN of each chip;

[0030] A pin CSN of each chip is electrically connected to a resistor RCSN, and a pin CSC of each chip is electrically connected to a resistor RCSC.

[0031] In a certain embodiment of the second aspect, the present invention also includes a PCB board, all LED constant current drive chips, rectifier units, energy storage capacitors CAP and load LED units are single-sidedly soldered on one side of the PCB board, the load LED unit is located on the right side of one side of the PCB board, the energy storage capacitor CAP and all LED constant current drive chips are on the left side of the load LED unit, and are arranged in sequence from bottom to top, and the rectifier unit is on the left side of the energy storage capacitor CAP.

[0032] In actual use, the working process of the lighting device of the present invention is as follows:

[0033] When the absolute value |VIN(θ)| of the voltage VIN(θ) input to the rectifier unit is greater than the voltage VCAP of the energy storage capacitor CAP, the bus voltage VBUS output by the rectifier unit supplies power to the load LED unit, and the negative end of the LED lamp at the end of the load LED unit, i.e., the pin DRN of the chip, also supplies power to the chip. At the same time, the bus voltage VBUS can charge the energy storage capacitor CAP, and the charging current is controlled by the first current control unit.

[0034] When |VIN(θ)| is less than the voltage drop of the load LED unit, the energy storage capacitor CAP in turn provides power to the load LED unit, that is, the energy storage capacitor CAP discharges to make the load LED unit and the chip work, and the current of the energy storage capacitor CAP flows out from the bus, from the ground end of the chip through the MOS tube Q1 back to the negative end of the energy storage capacitor CAP. In addition, whether it is powered by the bus voltage VBUS or the energy storage capacitor CAP, the output end of the second current control unit always controls the gate of the MOS tube Q2 to control the equivalent resistance of the MOS tube Q2, so that the current flowing through the MOS tube Q2, that is, the LED current, is equal to VREF / RCSN. The bus voltage VBUS charges the energy storage capacitor CAP, and the first current control unit controls the charging current to be VEA1+ / RCSC.

[0035] Unlike existing products, the charging current of the energy storage capacitor CAP of the present invention is not reversely compensated, but is detected by the voltage of the pin CSC. When |VIN(θ)| is less than the voltage VCAP, the energy storage capacitor CAP discharges to the load LED unit, and the current flows from the ground through the resistor RCSC and then through the internal MOS tube Q1 back to the negative end of the energy storage capacitor CAP, so the voltage of the pin CSC is less than GND.

[0036] When |VIN(θ)| is greater than the voltage VCAP, the energy storage capacitor CAP is charged, and the current flowing through the resistor RCSC begins to turn, and the voltage of the pin CSC quickly changes from a negative value to a positive value. It is only necessary to set the first reference voltage to a value slightly lower than the second reference voltage. When the voltage of the pin CSC exceeds the first reference voltage, the comparator CMP outputs a high level and transmits it to the pulse generation unit. After receiving the rising edge, the pulse generation unit will output a pulse voltage, which is superimposed with the second reference voltage and transmitted to the positive input terminal of the operational amplifier EA1.

[0037] According to the control principle of the first current control unit, the charging current of the energy storage capacitor CAP is (VREF+VPLUS) / RCSC. Since VPLUS is a pulse voltage with a very short duration, the charging current of the energy storage capacitor CAP has a pulse after the charging point starts and then returns to a normal state. According to the current superposition principle, the input current has a pulse state when |VIN(θ)| is greater than VCAP and then returns to a normal level, achieving the effect of sampling the bus voltage and delaying the CAP charging current to generate a peak current.

[0038] Compared with the prior art, the present invention has the following beneficial effects: From the above working process of the present invention, it can be seen that, firstly, the lighting device of the present invention can reversely compensate the CAP charging current to produce the peak current effect without using a resistor for bus voltage detection, so that when multiple chips are connected in parallel, there is no need to use a jumper resistor to transmit the detected bus voltage to each chip, thereby saving the application cost when multiple chips are connected in parallel in the lighting device;

[0039] Secondly, the reduction of the jumper resistance also increases the creepage distance between the negative end of the energy storage capacitor CAP and other nodes, thereby increasing the reliability of the lighting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is an application circuit diagram of an existing single linear constant current control chip;

[0041] Figure 2 It is a circuit diagram of parallel application of multiple existing linear constant current control chips;

[0042] Figure 3 for Figure 2 Schematic diagram of the circuit package on one side of the PCB board;

[0043] Figure 4 This is a circuit diagram of the LED constant current driver chip in Example 1;

[0044] Figure 5 This is a circuit diagram of the LED constant current driver chip in Example 2;

[0045] Figure 6 is a circuit diagram of the lighting device in Embodiment 3;

[0046] Figure 7 is a circuit diagram of the lighting device in Embodiment 4;

[0047] Figure 8 is a circuit diagram of the lighting device in Embodiment 5;

[0048] Fig. 9 is a circuit diagram of the lighting device in Embodiment 6;

[0049] Fig.10 for Figure 1 Waveform diagram of relevant signals during circuit simulation;

[0050] Fig.11 A waveform diagram of a relevant signal during simulation of the first lighting device;

[0051] Fig.12 This is a waveform diagram of relevant signals during simulation of the second lighting device. DETAILED DESCRIPTION

[0052] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0053] Embodiment 1

[0054] like Figure 4 As shown, the LED constant current driving chip provided in this embodiment includes a comparator CMP, a pulse generating unit 1, an adder 2, a first current control unit 3 and a second current control unit 4;

[0055] The positive input terminal of the comparator CMP is electrically connected to the input terminal of the first current control unit 3, and the negative input terminal of the comparator CMP is used to input the first reference voltage VREF1;

[0056] The output end of the comparator CMP is electrically connected to the pulse generating unit 1. After receiving the trigger signal that changes from a low level to a high level, the pulse generating unit 1 inputs a pulse signal to an input end of the adder 2. The other input end of the adder 2 is used for the second reference voltage VREF2. The output end of the adder 2 is electrically connected to the control end of the first current control unit 3.

[0057] The control end of the second current control unit 4 is used to access the second reference voltage VREF2 , and the input end of the second current control unit 4 is used to connect to an external load.

[0058] In actual use, the input end of the first current control unit 3 is used to connect an external energy storage capacitor, the first current control unit 3 is used to adjust the current flowing through the energy storage capacitor, and the second current control unit 4 is used to control the current flowing through the load.

[0059] Specifically, Figure 4 As shown, the LED constant current driver chip in this embodiment also includes a high-voltage power supply unit 5 and a reference unit 6. The high-voltage power supply unit 5 is electrically connected to the input end of the second current control unit 4, and the reference unit 6 is electrically connected to the output end of the high-voltage power supply unit 5. The first reference voltage VREF1 and the second reference voltage VREF2 are generated based on the voltage output by the high-voltage power supply unit 5.

[0060] In actual use, the high voltage power supply unit 5 and the reference unit 6 do not need to be connected to the first reference voltage VREF1 and the second reference voltage VREF2. In addition, the high voltage power supply unit 5 and the reference unit 6 are both existing technologies and will not be described in detail here.

[0061] exist Figure 4 In the embodiment, the first current control unit 3 includes an operational amplifier EA1 and a MOS tube Q1, the positive electrode of the operational amplifier EA1 is the control end of the first current control unit 3, the negative electrode of the operational amplifier EA1 is electrically connected to the source of the MOS tube Q1, the source of the MOS tube Q1 is the output end of the first current control unit 3, the output end of the operational amplifier EA1 is electrically connected to the gate of the MOS tube Q1, the drain of the MOS tube Q1 is the input end of the first current control unit 3, and the source of the MOS tube Q1 is the output end of the first current control unit 3.

[0062] exist Figure 4In the embodiment, the second current control unit 4 includes an operational amplifier EA2 and a MOS tube Q2, the positive electrode of the operational amplifier EA2 is the control end of the second current control unit 4, the negative electrode of the operational amplifier EA2 is electrically connected to the source of the MOS tube Q2, the source of the MOS tube Q2 is the output end of the second current control unit 4, the output end of the operational amplifier EA2 is electrically connected to the gate of the MOS tube Q2, the drain of the MOS tube Q2 is the input end of the second current control unit 4, and the source of the MOS tube Q2 is the output end of the second current control unit 4.

[0063] In this embodiment, the present invention further comprises a chip body 100, on which a comparator CMP, a pulse generating unit 1, an adder 2, a first current control unit 3, a second current control unit 4, a high voltage power supply unit 5 and a reference unit 6 are provided;

[0064] The chip body 100 is also provided with pins DRC, DRN, CSC, CSN and a ground pin. The input end of the first current control unit 3 is electrically connected to the pin DRC, the input end of the second current control unit 4 is electrically connected to the pin DRN, the output end of the first current control unit 3 is electrically connected to the pin CSC, the output end of the second current control unit 4 is electrically connected to the pin CSN, and the ground pin is used to be electrically connected to the ground terminal in the circuit.

[0065] It should be noted that Figure 6 The distribution of the pins DRC, DRN, CSC, CSN and ground pins in FIG. 1 is only for the convenience of displaying the LED constant current driver chip, and is not the actual pin distribution position. The actual distribution of the pins DRC, DRN, CSC, CSN and ground pins on the chip body 100 is as follows:

[0066] The first current control unit 3 and the second current control unit 4 are distributed on the chip body 100 on the left and right. The first current control unit 3 is on the right side of the chip body 100, and the second current control unit 4 is on the left side of the chip body 100. The pin DRC and the ground pin are located on the upper side of the chip body, and the pin CSC, pin CSN and pin DRN are located on the lower side of the chip body. For details, please refer to the pin distribution of the chip in Example 5.

[0067] It should be noted that the working process of the LED constant current driver chip in this embodiment is described in conjunction with the lighting device in the third embodiment, and will not be described again here.

[0068] Embodiment 2

[0069] like Figure 5As shown, this embodiment provides another structure of the LED constant current driver chip. The difference from the LED constant current driver chip in the first embodiment is that the positive input terminal of the comparator CMP of the LED constant current driver chip in this embodiment is electrically connected to the output terminal of the first current control unit 3, that is, electrically connected to the source of the MOS tube Q1.

[0070] Similarly, the working process of the LED constant current driving chip in this embodiment refers to the relevant content in the third embodiment, and no redundant description is given here.

[0071] Embodiment 3

[0072] like Figure 6 As shown, this embodiment provides a lighting device, including an LED constant current driver chip in the first embodiment, and also includes a rectifier unit 7, an energy storage capacitor CAP and a load LED unit 8, the load LED unit 8 includes N LED lamps, N is a positive integer, when N is greater than 1, all the LED lamps are connected in series in sequence;

[0073] The output end of the rectifier unit 7 is electrically connected to the positive electrode of the energy storage capacitor CAP and the positive electrode of the first-end LED lamp respectively, the negative electrode of the energy storage capacitor CAP is electrically connected to the pin DRC of the chip, and the negative electrode of the terminal LED lamp is electrically connected to the pin DRN of the chip;

[0074] The pins CSN of the chip are electrically connected to the resistors RCSN, and the pins CSC of the chip are electrically connected to the resistors RCSC.

[0075] In this embodiment, the rectifying unit 7 is an existing rectifying circuit, which will not be described in detail here.

[0076] The working process of the lighting device in this embodiment is as follows:

[0077] When the absolute value |VIN(θ)| of the voltage VIN(θ) input to the rectifier unit 7 is greater than the voltage VCAP of the energy storage capacitor CAP, the bus voltage VBUS output by the rectifier unit 7 supplies power to the load LED unit 8, and the negative end of the LED lamp at the end of the load LED unit 8, that is, the pin DRN of the chip, also supplies power to the chip. At the same time, the bus voltage VBUS can charge the energy storage capacitor CAP, and the charging current is controlled by the first current control unit 3.

[0078] When |VIN(θ)| is less than the voltage drop of the load LED unit 8, the energy storage capacitor CAP in turn provides power to the load LED unit 8, that is, the energy storage capacitor CAP discharges to make the load LED unit 8 and the chip work, and the current of the energy storage capacitor CAP flows out from the bus, and returns to the negative end of the energy storage capacitor CAP from the ground end of the chip through the MOS tube Q1. In addition, whether it is powered by the bus voltage VBUS or the energy storage capacitor CAP, the output end of the second current control unit 4 always controls the gate of the MOS tube Q2 to control the equivalent resistance of the MOS tube Q2, so that the current flowing through the MOS tube Q2, that is, the LED current, is equal to VREF / RCSN. The bus voltage VBUS charges the energy storage capacitor CAP, and the first current control unit 3 controls the charging current to VEA1+ / RCSC, where VEA1+ is the voltage of the positive input end of the operational amplifier EA1.

[0079] Unlike existing products, the charging current of the energy storage capacitor CAP of the present invention is not reversely compensated, but is detected by the voltage of the pin CSC. When |VIN(θ)| is less than the voltage VCAP, the energy storage capacitor CAP discharges to the load LED unit 4, and the current flows from the ground through the resistor RCSC and then through the internal MOS tube Q1 back to the negative end of the energy storage capacitor CAP, so the voltage of the pin CSC is less than GND.

[0080] When |VIN(θ)| is greater than the voltage VCAP, the energy storage capacitor CAP is charged, and the current flowing through the resistor RCSC begins to turn, and the voltage of the pin CSC quickly changes from a negative value to a positive value. It is only necessary to set the first reference voltage VREF1 to a value slightly lower than the voltage of the second reference voltage VREF2; when the voltage of the pin CSC exceeds the first reference voltage VREF1, the comparator CMP outputs a high level and transmits it to the pulse generating unit 1. After receiving the rising edge, the pulse generating unit 1 will output a pulse voltage, which is superimposed on the second reference voltage VREF2 and transmitted to the positive input terminal of the operational amplifier EA1.

[0081] According to the control principle of the first current control unit 3, the charging current of the energy storage capacitor CAP is (VREF+VPLUS) / RCSC. Since VPLUS is a pulse voltage with a very short duration, the charging current of the energy storage capacitor CAP has a pulse after the charging point starts and then returns to a normal state. According to the current superposition principle, the input current has a pulse state when |VIN(θ)| is greater than VCAP and then returns to a normal level, achieving the effect of sampling the bus voltage and delaying the CAP charging current to generate a peak current.

[0082] It should be noted that Figure 7 The chip in the lighting device is provided with the LED constant current driver chip in the first embodiment. Figure 7The lighting device in the embodiment is taken as the first lighting device; when the LED constant current driver chip in the embodiment 2 is set on the chip in the lighting device, the lighting device is recorded as the second lighting device;

[0083] right Figure 1 The circuit, the first lighting device and the second lighting device in the embodiment are simulated, and the simulation diagrams are shown in FIG. Fig.10 , Fig.11 and Fig.12 As shown, the input voltage is the AC voltage input to the rectifier unit 7, the input current is the input current of the power grid, the CAP current is the charging current of the energy storage capacitor CAP, and the LED current is the current flowing through the load LED unit 8;

[0084] from Fig.10 , Fig.11 and Fig.12 It can be obtained that under the same input voltage, the LED currents of the first lighting device and the second lighting device are the same and have no ripple current. Since the output current is a straight line, the form of the input current is the form of the CAP current. The peak current of the input current is formed by the peak current of the energy storage capacitor CAP, and the peak current of the input current of the driving circuit of the present invention is the same as that of the existing product.

[0085] Embodiment 4

[0086] This embodiment provides a lighting device of another structure. Different from the lighting device in the third embodiment, the lighting device in this embodiment includes an LED constant current driver chip in the second embodiment; and also includes a rectifier unit 7, an energy storage capacitor CAP and a load LED unit 8. The load LED unit 8 includes N LED lamps, where N is a positive integer. When N is greater than 1, all the LED lamps are connected in series in sequence.

[0087] Specifically, in this embodiment, the connection relationship between the LED constant current driving chip, the rectifier unit 7, the energy storage capacitor CAP and the load LED unit 8 and the working process of the entire lighting device can refer to the contents of Example 3, and no redundant description is given here.

[0088] Embodiment 5

[0089] like Figure 8 As shown, this embodiment provides another structure of a lighting device, including three LED constant current driver chips in the third embodiment, and also including a rectifier unit 7, an energy storage capacitor CAP and a load LED unit 8, the load LED unit 8 includes N LED lamps, N is a positive integer, when N is greater than 1, all the LED lamps are connected in series in sequence;

[0090] The output end of the rectifier unit 7 is electrically connected to the positive electrode of the energy storage capacitor CAP and the positive electrode of the first-end LED lamp respectively, the negative electrode of the energy storage capacitor CAP is electrically connected to the pin DRC of each chip, and the negative electrode of the terminal LED lamp is electrically connected to the pin DRN of each chip;

[0091] A pin CSN of each chip is electrically connected to a resistor RCSN, and a pin CSC of each chip is electrically connected to a resistor RCSC.

[0092] In some implementations, the remaining number of LED constant current driver chips may be provided according to actual needs. For example, two, four, five or six LED constant current driver chips may be provided, which is not limited here.

[0093] In addition, the working process of the lighting device in this embodiment refers to the third embodiment, and no redundant description is given here.

[0094] Embodiment 6

[0095] like Fig. 9 As shown, the lighting device provided in this embodiment further includes a PCB board 101, and all LED constant current drive chips, the rectifier unit 7, the energy storage capacitor CAP and the load LED unit 8 are single-sidedly welded on one side of the PCB board 100;

[0096] Specifically, the load LED unit 8 is located on the right side of one side of the PCB board 101, the energy storage capacitor CAP and all LED constant current drive chips are on the left side of the load LED unit, and are arranged in sequence from bottom to top, and the rectifier unit 7 is on the left side of the energy storage capacitor CAP.

[0097] When the lighting device in this embodiment is actually used, firstly, because no jumper resistor is used to transmit the detected bus voltage to each chip, the application cost of connecting multiple chips in parallel in the lighting device is saved;

[0098] Secondly, the reduction of jumper resistance also increases the creepage distance between the negative end of the energy storage capacitor CAP and other nodes, thereby increasing the reliability of the lighting device;

[0099] Finally, the packaging of the driver chip of the present invention is the same as that of the existing driver chip, and can be well compatible with the illumination device using the existing driver chip.

[0100] The above is based on the present invention as an inspiration. Through the above description, relevant staff can make various changes and modifications without departing from the technical idea of ​​this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A LED constant current driver chip, characterized in that: It includes a comparator CMP, a pulse generating unit, an adder, a first current control unit and a second current control unit; The positive input terminal of the comparator CMP is electrically connected to the input terminal of the first current control unit, and the negative input terminal of the comparator CMP is used to input the first reference voltage; The output end of the comparator CMP is electrically connected to the pulse generating unit, and the pulse generating unit inputs a pulse signal to an input end of the adder after receiving a trigger signal that changes from a low level to a high level, and the other input end of the adder is used for a second reference voltage, and the output end of the adder is electrically connected to the control end of the first current control unit; The control end of the second current control unit is used to access the second reference voltage, and the input end of the second current control unit is used to connect to an external load.

2. A LED constant current driver chip, characterized in that: It includes a comparator CMP, a pulse generating unit, an adder, a first current control unit and a second current control unit; The positive input terminal of the comparator CMP is electrically connected to the output terminal of the first current control unit, and the negative input terminal of the comparator CMP is used to input the first reference voltage; The output end of the comparator CMP is electrically connected to the pulse generating unit, and the pulse generating unit inputs a pulse signal to an input end of the adder after receiving a trigger signal that changes from a low level to a high level, and the other input end of the adder is used for a second reference voltage, and the output end of the adder is electrically connected to the control end of the first current control unit; The control end of the second current control unit is used to access the second reference voltage, and the input end of the second current control unit is used to connect to an external load.

3. An LED constant current driver chip according to claim 1 or 2, characterized in that: It also includes a high-voltage power supply unit and a reference unit, wherein the high-voltage power supply unit is electrically connected to the input end of the second current control unit, and the reference unit is electrically connected to the output end of the high-voltage power supply unit, and the first reference voltage and the second reference voltage are generated based on the voltage output by the high-voltage power supply unit.

4. An LED constant current driver chip according to claim 1, 2 or 3, characterized in that: The first current control unit includes an operational amplifier EA1 and a MOS tube Q1, wherein the anode of the operational amplifier EA1 is the control end of the first current control unit, the cathode of the operational amplifier EA1 is electrically connected to the source of the MOS tube Q1, the source of the MOS tube Q1 is the output end of the first current control unit, the output end of the operational amplifier EA1 is electrically connected to the gate of the MOS tube Q1, and the drain of the MOS tube Q1 is the input end of the first current control unit.

5. The LED constant current driver chip according to claim 4, characterized in that: The second current control unit includes an operational amplifier EA2 and a MOS tube Q2, wherein the positive electrode of the operational amplifier EA2 is the control end of the second current control unit, the negative electrode of the operational amplifier EA2 is electrically connected to the source of the MOS tube Q2, the source of the MOS tube Q2 is the output end of the second operational amplifier unit, the output end of the operational amplifier EA2 is electrically connected to the gate of the MOS tube Q2, and the drain of the MOS tube Q2 is the input end of the second current control unit.

6. The LED constant current driver chip according to claim 5, characterized in that: It also includes a chip body, on which the comparator CMP, the pulse generating unit, the adder, the first current control unit, the second current control unit, the high-voltage power supply unit and the reference unit are all arranged; The chip body is also provided with pins DRC, DRN, CSC, CSN and a ground pin. The input end of the first current control unit is electrically connected to the pin DRC, the input end of the second current control unit is electrically connected to the pin DRN, the output end of the first current control unit is electrically connected to the pin CSC, the output end of the second current control unit is electrically connected to the pin CSN, and the ground pin is used to be electrically connected to the ground terminal in the circuit.

7. The LED constant current driver chip according to claim 6, characterized in that: The first current control unit and the second current control unit are distributed on the left and right of the chip body, the pin DRC and the ground pin are located on the upper side of the chip body, and the pin CSC, the pin CSN and the pin DRN are located on the lower side of the chip body.

8. A lighting device, characterized in that: The method comprises at least one LED constant current driver chip as claimed in claim 7, and further comprises a rectifier unit, an energy storage capacitor CAP and a load LED unit, wherein the load LED unit comprises N LED lamps, N is a positive integer, and when N is greater than 1, all the LED lamps are connected in series in sequence; The output end of the rectifier unit is electrically connected to the positive electrode of the energy storage capacitor CAP and the positive electrode of the first-end LED lamp respectively, the negative electrode of the energy storage capacitor CAP is electrically connected to the pin DRC of each chip, and the negative electrode of the terminal LED lamp is electrically connected to the pin DRN of each chip; A pin CSN of each chip is electrically connected to a resistor RCSN, and a pin CSC of each chip is electrically connected to a resistor RCSC.

9. The lighting device according to claim 8, characterized in that: It also includes a PCB board, all LED constant current drive chips, a rectifier unit, an energy storage capacitor CAP and a load LED unit are single-sidedly welded on one side of the PCB board, the load LED unit is located on the right side of one side of the PCB board, the energy storage capacitor CAP and all LED constant current drive chips are on the left side of the load LED unit, and are arranged in sequence from bottom to top, and the rectifier unit is on the left side of the energy storage capacitor CAP.

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