A linear LED control chip and driving circuit
By using a linear LED control chip and driver circuit with a shared capacitor in the LED color temperature linear drive circuit, the problem of large circuit size in the prior art is solved, and more flexible color temperature control is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU YUANWEI SEMICON TECH CO LTD
- Filing Date
- 2025-07-16
- Publication Date
- 2026-07-21
AI Technical Summary
Existing LED color-tuning linear drive circuits require two large-value capacitors for output filtering, resulting in a large circuit size.
A linear LED control chip is used. By setting diodes D1, D2, and D3, the first current control unit and the second current control unit share a capacitor CAP. The reference input voltage is adjusted through a reference unit, a current source ICCT, and a voltage-controlled voltage source VCVS to achieve color temperature control.
It simplifies the circuit structure and size, and enables more possible color temperature control effects.
Smart Images
Figure CN224538367U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of LED control technology, specifically to a linear LED control chip and driving circuit. Background Technology
[0002] In LED lighting applications, linear color tuning of LEDs is often required to achieve smooth color transitions, accurately match scene requirements, and improve visual comfort.
[0003] The linear drive circuits used in existing LED color-tuning linear drive circuit applications, such as Figure 1 As shown; the main power of this circuit is divided into two independent LED branches: one is a high color temperature branch (LEDW), and the other is a low color temperature branch (LEDY), with the LEDs having the same rated operating voltage. For Figure 1 The circuit shown works as follows: The input AC voltage VIN is rectified into a pulsating bus voltage after passing through the rectifier bridge. The bus voltage is denoted as VBUS. When VBUS is less than the start-up voltage VLED of the load LED, the load LED does not work. When VBUS is greater than the start-up voltage VLED, the two current control modules start working. VBUS flows through the load LED and the MOSFETs QW and QY of the two current control modules. The current flowing through the load LED is controlled at VREF / RCWX and VREF / RCYX, where X is 1, 2, or 4, and the specific values of RCSX and RCYX depend on the position of the DIP switch SW; Figure 1 If SW is in the middle, then RCWX and RCYX are RCW2 and RCY2 respectively. If it is in the left gear, then RCW1 and RCS1. If it is in the right gear, then RCW3 and RCY3. Additionally, since the input AC voltage is undervoltage relative to the load LED, the current flowing through the LED is ILEDX = VREF / RCWX * (T) LED_WORK / T LINE ). Among them, T LED_WORK T represents the time during which VBUS is greater than the LED operating voltage within the power frequency cycle. LINE This refers to the power grid frequency cycle.
[0004] exist Figure 1 In this circuit, the capacitor CAP filters the current flowing through the LED to smooth the output current. At the same time, by controlling the unit of the DIP switch SW, different resistance combinations are achieved, thereby generating different high color temperature and low color temperature currents, ultimately achieving the effect of mixing high and low color temperatures.
[0005] for Figure 1The circuit shown has two independent LED branches, and their power ratio is entirely controlled by the resistance values of RCWX and RCYX to maintain the mixing ratio of high and low color temperatures. To meet performance requirements in all situations, when only high or low color temperature is needed, the load LED in one LED branch is not working. Therefore, the load LED in the other LED branch must carry all current to maintain constant power. Thus, capacitor CAP must be designed to accommodate the current ripple required for the load LED in one LED branch to carry full power under extreme conditions. Therefore, the dimming scheme requires one capacitor CAP for each color temperature to meet the current requirements for one LED branch carrying all current. Consequently, existing color-tuning linear LED driver circuits require two capacitor CAPs, resulting in large size and high capacitance requirements. Utility Model Content In view of the shortcomings of the prior art, the present invention provides a linear LED control chip and driving circuit. The technical problem to be solved is that when existing LEDs are driven linearly for color adjustment, two large-value capacitors are required for output filtering, resulting in a large circuit size.
[0006] To solve the above technical problems, in the first aspect, this utility model provides the following technical solution: a linear LED control chip, including a first current control unit, a second current control unit, diode D1, diode D2 and diode D3; The reference input terminal of the first current control unit and the reference input terminal of the second current control unit are respectively used to input reference voltages. The input terminal of the first current control unit is electrically connected to the cathode of diode D2; the input terminal of the second current control unit is electrically connected to the cathode of diode D3. The anodes of diode D3 and diode D2 are both electrically connected to the cathode of diode D1, and the anode of diode D1 is grounded.
[0007] In one embodiment of the first aspect, the first current control unit includes an operational amplifier EAW and a MOSFET QW, wherein the positive input terminal of the operational amplifier EAW is the reference input terminal of the first current control unit. The output terminal of the operational amplifier EAW is electrically connected to the gate of the MOSFET QW, the drain of the MOSFET QW is the input terminal of the first current control unit, and the source of the MOSFET QW is electrically connected to the negative input terminal of the operational amplifier EAW. The second current control unit includes an operational amplifier EAY and a MOSFET QY. The positive input terminal of the operational amplifier EAY is the reference input terminal of the second current control unit. The output terminal of operational amplifier EAY is electrically connected to the gate of MOSFET QY, the drain of MOSFET QY is the input terminal of the second current control unit, and the source of MOSFET QY is electrically connected to the negative input terminal of operational amplifier EAY.
[0008] In one embodiment of the first aspect, the present invention further includes a power supply unit, a reference unit, a current source ICCT, and a reference voltage generation unit; The power supply unit generates a power supply voltage based on an external input voltage, and the reference unit generates a reference voltage VREF based on the power supply voltage; the current source ICCT generates an operating current based on the power supply voltage, and the output terminal of the current source ICCT is electrically connected to the reference input terminal of the first current control unit; the reference voltage generation unit generates a reference voltage VREFY, which is input to the reference input terminal of the second current control unit, based on the reference voltage VREF and the voltage at the output terminal of the current source ICCT.
[0009] In one embodiment of the first aspect, the reference voltage generating unit generates a reference voltage VREFY based on the difference between the reference voltage VREF and the voltage at the output terminal of the current source ICCT.
[0010] In one embodiment of the first aspect, the reference voltage generating unit includes a voltage-controlled voltage source VCVS, the positive input terminal of the voltage-controlled voltage source VCVS is used to input the reference voltage VREF, the negative input terminal of the voltage-controlled voltage source VCVS is electrically connected to the output terminal of the current source ICCT, the positive output terminal of the voltage-controlled voltage source VCVS is used to output the reference voltage VREFY, and the negative output terminal of the voltage-controlled voltage source VCVS is grounded.
[0011] In one embodiment of the first aspect, the power supply unit includes a transistor JFET and a capacitor CVCC. The input terminal of the transistor JFET is used to input the external input voltage, and the output terminal of the transistor JFET is electrically connected to one end of the capacitor CVCC to output the power supply voltage. The other end of the capacitor CVCC is grounded.
[0012] In one embodiment of the first aspect, the output terminal of the current source ICCT is further electrically connected to a clamping unit, which is used to clamp the voltage at the output terminal of the current source ICCT.
[0013] In one embodiment of the first aspect, the present invention further includes a chip body, wherein the power supply unit, reference unit, current source ICCT, reference voltage generation unit, first current control unit, second current control unit, diode D1, diode D2, diode D3 and clamping unit are all disposed on the chip body; The chip body also has an HV pin, a CAP pin, a DRN_W pin, a DRN_Y pin, a CS_Y pin, a CS_W pin, a CCT pin, and a GND pin. The HV pin is electrically connected to the power supply unit and is used to input the external input voltage. The CAP pin is electrically connected to the cathode of diode D1. The DRN_W pin is electrically connected to the cathode of diode D2. The DRN_Y pin is electrically connected to the cathode of diode D3. The CS_Y pin is electrically connected to the output terminal of the second current control unit. The CS_W pin is electrically connected to the output terminal of the first current control unit. The CCT pin is electrically connected to the output terminal of the current source ICCT. The GND pin is electrically connected to all ground terminals of the chip.
[0014] The second utility model provides a linear LED driving circuit, including the aforementioned linear LED control chip, and further including a rectifier bridge, a capacitor CAP, and a load unit. The positive output terminal of the rectifier bridge is electrically connected to the anode of diode D4. The cathode of diode D4 is electrically connected to the HV pin and the positive terminal of capacitor CAP, respectively. The negative terminal of capacitor CAP is electrically connected to the CAP pin. The positive terminal of capacitor CAP and the DRN_W pin are used to electrically connect to the two ends of the high color temperature LED branch. The positive terminal of capacitor CAP and the DRN_Y pin are used to electrically connect to the two ends of the low color temperature LED branch. The CS_Y pin is grounded through resistor RCY, the CS_W pin is grounded through resistor RCW, and the CCT pin is grounded through the load unit. The load unit is used to provide an adjustable resistance load branch from the output terminal of current source ICCT to the ground terminal. The GND pin is grounded.
[0015] Thirdly, this utility model provides a linear LED driving circuit with another structure, including the aforementioned linear LED control chip, and further including a rectifier bridge, a capacitor CAP, and a reference voltage generating unit. The positive output terminal of the rectifier bridge is electrically connected to the anode of diode D4. The cathode of diode D4 is electrically connected to the HV pin and the positive terminal of capacitor CAP, respectively. The negative terminal of capacitor CAP is electrically connected to the CAP pin. The positive terminal of capacitor CAP and the DRN_W pin are used to electrically connect to the two ends of the high color temperature LED branch. The positive terminal of capacitor CAP and the DRN_Y pin are used to electrically connect to the two ends of the low color temperature LED branch. The CS_Y pin is grounded through resistor RCY, and the CS_W pin is grounded through resistor RCW. The reference voltage generating unit is electrically connected to the CCT pin and is used to generate an adjustable reference voltage VREFW at the CCT pin. The GND pin is grounded.
[0016] The advantages of this utility model compared with the prior art are: 1. The control chip of this utility model uses diodes D1, D2 and D3, so that the first current control unit and the second current control unit can share a capacitor CAP when actually controlling the current of the high color temperature LED branch and the low color temperature LED branch, thereby simplifying the circuit structure and size. Second: By setting up a reference unit, a current source ICCT, and a voltage-controlled voltage source VCVS, and by setting an adjustable resistance load branch on the CCT pin or setting an adjustable output voltage reference voltage generation unit, the voltage input to the reference input terminals of the first and second current control units can be changed. Compared with changing the resistance value by using a DIP switch, this invention can achieve more possible color temperature control. Attached Figure Description
[0017] Figure 1 The circuit diagram is for an existing linear LED driver circuit with adjustable color temperature. Figure 2 This is a schematic diagram of the control chip in Example 1; Figure 3 The circuit diagram is shown for the linear LED driving circuit in Example 2. Figure 4 for Figure 3 Simulation waveforms of currents ILEDW and ILEDY during circuit simulation; Figure 5 for Figure 3 The power waveform of the input AC power supply during circuit simulation; Figure 6 This is a circuit diagram of the linear LED driving circuit in Example 2. Detailed Implementation
[0018] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.
[0019] Example 1 like Figure 2 As shown, this embodiment provides a linear LED control chip, including a first current control unit 2, a second current control unit 3, diode D1, diode D2 and diode D3; The reference input terminal of the first current control unit 2 and the reference input terminal of the second current control unit 3 are respectively used to input a reference voltage with an adjustable voltage value. The input terminal of the first current control unit 2 is electrically connected to the cathode of diode D2; the input terminal of the second current control unit 3 is electrically connected to the cathode of diode D3. The anodes of diode D3 and diode D2 are both electrically connected to the cathode of diode D1, and the anode of diode D1 is grounded.
[0020] In practical use, the cathode of diode D1 is used to connect to capacitor CAP. In this embodiment, the control chip uses diodes D1, D2, and D3 so that the first current control unit 2 and the second current control unit 3 can share a single capacitor CAP when actually controlling the current of the high color temperature LED branch and the low color temperature LED branch, thereby simplifying the circuit structure and size. The principle of sharing a single capacitor CAP is explained in Embodiment 2 and will not be described again here.
[0021] In this embodiment, Figure 2 In the first current control unit 2, there are operational amplifier EAW and MOSFET QW. The positive input terminal of operational amplifier EAW is the reference input terminal of the first current control unit 2. The output terminal of the operational amplifier EAW is electrically connected to the gate of the MOSFET QW, the drain of the MOSFET QW is the input terminal of the first current control unit 2, and the source of the MOSFET QW is electrically connected to the negative input terminal of the operational amplifier EAW.
[0022] In this embodiment, Figure 2 In the second current control unit 3, there are operational amplifier EAY and MOSFET QY. The positive input terminal of operational amplifier EAY is the reference input terminal of the second current control unit 3. The output terminal of the operational amplifier EAY is electrically connected to the gate of the MOSFET QY, the drain of the MOSFET QY is the input terminal of the second current control unit 3, and the source of the MOSFET QY is electrically connected to the negative input terminal of the operational amplifier EAY.
[0023] In this embodiment, the reference input terminals of the first current control unit 2 and the second current control unit 3 are respectively connected to a reference voltage generation circuit with an adjustable voltage value, as follows: exist Figure 2 In addition, this utility model also includes a power supply unit 1, a reference unit, a current source ICCT, and a reference voltage generation unit 10; The power supply unit 1 generates a power supply voltage based on the external input voltage, and the reference unit generates a reference voltage VREF based on the power supply voltage; the current source ICCT generates an operating current based on the power supply voltage, and the output terminal of the current source ICCT is electrically connected to the reference input terminal of the first current control unit 2; the reference voltage generation unit 10 generates a reference voltage VREFY that is input to the reference input terminal of the second current control unit 3 based on the reference voltage VREF and the voltage at the output terminal of the current source ICCT. More specifically, the reference voltage generation unit 10 generates a reference voltage VREFY based on the difference between the reference voltage VREF and the voltage at the output terminal of the current source ICCT.
[0024] exist Figure 2 In the reference voltage generation unit 10, there is a voltage-controlled voltage source VCVS. The positive input terminal of the voltage-controlled voltage source VCVS is used to input the reference voltage VREF. The negative input terminal of the voltage-controlled voltage source VCVS is electrically connected to the output terminal of the current source ICCT. The positive output terminal of the voltage-controlled voltage source VCVS is used to output the reference voltage VREFY. The negative output terminal of the voltage-controlled voltage source VCVS is grounded.
[0025] In practical use, the reference voltage VREF input to the positive input terminal of the voltage-controlled voltage source VCVS is fixed. When the voltage at the negative input terminal of the voltage-controlled voltage source VCVS, i.e., the output terminal of the current source ICCT, changes, the reference voltage VREFY output from the positive output terminal of the voltage-controlled voltage source VCVS changes. This changes the magnitude of the reference voltage input to the reference input terminals of the first current control unit 2 and the second current control unit 3, thereby achieving color temperature adjustment control. In addition, in this embodiment, the voltage at the output terminal of the current source ICCT is used as the reference voltage VREFW, so VREFY + VREFW = VREF. At this time, the voltage-controlled voltage source VCVS outputs the difference between the reference voltage VREF and the voltage at the output terminal of the current source ICCT in a proportional manner.
[0026] In one implementation, an adjustable reference voltage VREFY can be generated by proportionally amplifying or reducing the difference between the reference voltage VREF and the voltage at the output of the current source ICCT using other circuitry.
[0027] Specifically, in this embodiment, in Figure 2 In the power supply unit 1, there are a transistor JFET and a capacitor CVCC. The input terminal of the transistor JFET is used to input the external input voltage, and the output terminal of the transistor JFET is electrically connected to one end of the capacitor CVCC to output the power supply voltage. The other end of the capacitor CVCC is grounded.
[0028] Specifically, in this embodiment, in Figure 2 In the middle, the output terminal of the current source ICCT is also electrically connected to the clamping unit 4. The clamping unit 4 is used to clamp the voltage of the output terminal of the current source ICCT to prevent the voltage of the output terminal of the current source ICCT from being too high, thereby ensuring the normal operation of the control chip.
[0029] More specifically, in this embodiment, the clamping unit includes a Zener diode ZD, the cathode of which is electrically connected to the output terminal of the current source ICCT, and the anode of which is grounded.
[0030] In one embodiment, those skilled in the art can clamp the voltage at the output terminal of the current source ICCT based on the clamping circuit of other existing structures.
[0031] Specifically, in this embodiment, the present invention also includes a chip body, and the power supply unit 1, the reference unit, the current source ICCT, the reference voltage generation unit 10, the first current control unit 2, the second current control unit 3, the diode D1, the diode D2, the diode D3 and the clamping unit 4 are all disposed on the chip body. The chip body also has HV pin, CAP pin, DRN_W pin, DRN_Y pin, CS_Y pin, CS_W pin, CCT pin, and GND pin. The HV pin is electrically connected to power supply unit 1 and is used to input external input voltage. The CAP pin is electrically connected to the cathode of diode D1. The DRN_W pin is electrically connected to the cathode of diode D2. The DRN_Y pin is electrically connected to the cathode of diode D3. The CS_Y pin is electrically connected to the output terminal of the second current control unit 3. The CS_W pin is electrically connected to the output terminal of the first current control unit 2. The CCT pin is electrically connected to the output terminal of the current source ICCT. The GND pin is electrically connected to all ground terminals of the chip.
[0032] Example 3 like Figure 3 As shown, this embodiment provides a linear LED driving circuit, including the linear LED control chip in Embodiment 1, and also includes a rectifier bridge 7, a capacitor CAP, and a load unit 8. The positive output terminal of the rectifier bridge 7 is electrically connected to the anode of the diode D4. The cathode of the diode D4 is electrically connected to the HV pin and the positive terminal of the capacitor CAP, respectively. The negative terminal of the capacitor CAP is electrically connected to the CAP pin. The positive terminal of the capacitor CAP and the DRN_W pin are used to electrically connect to the two ends of the high color temperature LED branch 5. The positive terminal of the capacitor CAP and the DRN_Y pin are used to electrically connect to the two ends of the low color temperature LED branch 6. The CS_Y pin is grounded through the resistor RCY, the CS_W pin is grounded through the resistor RCW, and the CCT pin is grounded through the load unit 8. The load unit 8 is used to provide an adjustable resistance load branch from the output terminal of the current source ICCT to the ground terminal. The GND pin is grounded.
[0033] Specifically, in this embodiment, the load unit 8 includes a sliding rheostat RCT and a capacitor CCT, which are connected in parallel. The sliding end of the sliding rheostat RCT is electrically connected to the output end of the current source ICCT, and the ground end of the sliding rheostat RCT is grounded. By adjusting the resistance between the sliding end of the sliding rheostat and its own ground end, the voltage at the output end of the current source ICCT can be adjusted, thereby making the reference voltage input to the first current control unit 2 and the second current control unit 3 adjustable.
[0034] In one embodiment, the load unit 8 may further include a programmable digital potentiometer, which is controlled by a controller to adjust the resistance between the end of the programmable digital potentiometer electrically connected to the output terminal of the current source ICCT and the ground terminal.
[0035] In this embodiment, Figure 3 The working principle of the circuit shown is as follows: The voltage output from the positive output terminal of rectifier bridge 7 is denoted as voltage VBUS, and the voltage at which high color temperature LED branch 5 and low color temperature LED branch 6 start working is denoted as voltage VLED. In use, the voltage VBUS charges the capacitor CVCC through the HV pin and the transistor JFET in sequence. After the capacitor CVCC reaches the working voltage, the reference unit outputs the corresponding reference voltage VREF. When the voltage VBUS is less than the voltage VLED, the high color temperature LED branch 5 and the low color temperature LED branch 6 do not work; when the voltage VBUS is greater than the voltage VLED, the first current control unit 2 and the second current control unit 3 start to work, and the voltage VBUS flows into the MOSFET QW and MOSFET QY through the high color temperature LED branch 5 and the low color temperature LED branch 6 respectively, and the current flowing through them is controlled at VREF / RCW and VREF / RCY.
[0036] Clearly, due to the undervoltage condition VBUS, the average current flowing through the high color temperature LED branch 5 and the low color temperature LED branch 6 is not VREF / RCW and VREF / RCY, respectively. The presence of capacitor CAP filters the pulsating current flowing through MOSFETs QW and QY. When VBUS is not undervoltage, the excess current from the high color temperature LED branch 5 and the low color temperature LED branch 6 flows through capacitor CAP.
[0037] In this embodiment, diodes D2 and D3 separate the high color temperature LED branch 5 and the low color temperature LED branch 6. The current flowing through the high color temperature LED branch 5 can only pass through the MOSFET; conversely, the current flowing through the low color temperature LED branch 6 can only flow through the MOSFET QY. However, when the current flowing through the MOSFET QW exceeds the current flowing through the high color temperature LED branch 5 and the current flowing through the MOSFET QY exceeds the current flowing through the low color temperature LED branch 6, the excess current can share the storage capacitor CAP.
[0038] When the voltage VBUS is low, capacitor CAP will simultaneously supply power to both the high color temperature LED branch 5 and the low color temperature LED branch 6. Since the power supply from capacitor CAP to these two branches is insufficient to ensure that the current flowing through MOSFETs QW and QY reaches VREF / RCW and VREF / RCY, MOSFETs QW and QY remain fully turned on. The current flowing out of capacitor CAP passes through high color temperature LED branch 5 and low color temperature LED branch 6, then through MOSFETs QW and QY, then through resistors RCW and RCY, and finally returns to capacitor CAP via diode D1.
[0039] The current from the current source ICCT flows through the resistor RCCT connected to the CCT pin, generating a voltage denoted as VREFW. The capacitor CCT helps stabilize the voltage at the CCT pin. The maximum value of the CCT pin is limited by the Zener diode ZD, which can be designed as VREF. The difference between VREF and VREFW is denoted as VREFY, and the equation VREFW + VREFY = VREF clearly holds. When the resistance values of RCW and RCY are designed to be equal, denoted as RCS, VREFW / RCW + VREFY / RCY = VREF / RCS.
[0040] Changing the external resistor of the CCT pin generates different VREFW values, which are used to change the current distribution of MOSFETs QW and QY, while keeping the total current constant. This allows the high and low color temperature ratio to be changed while maintaining constant power, thus producing a color temperature adjustment effect.
[0041] right Figure 3 The circuit shown is simulated using EDA. The reference voltage VREF is set to 0.5V, resistors RCW and RCSY are set to 4Ω, the input power supply AC voltage is set to 120V, the rated voltage of voltage VLED is set to 120V, VREFW is modulated from VREF / 2 to VREF, and the current ILEDW flowing through the high color temperature LED branch 5 and the current ILEDY flowing through the low color temperature LED branch 6 are as follows: Figure 4 As shown, from Figure 4 It can be seen that the currents of ILEDW and ILEDY are initially equal. After the reference voltage VREFW gradually increases, the currents of ILEDW and ILEDY increase and decrease respectively.
[0042] The input power waveform of the input power supply AC is as follows Figure 5 As shown, after stabilization, there is no significant change. Simulation data shows that the input power when ILEDW = ILEDY is approximately 1.05 times the input power when ILEDW is at its maximum and ILEDY = 0. When VREFW changes from VREF / 2 to 0, the current changes of LEDW and LEDY are interchanged, but the input power changes are consistent.
[0043] Example 3 like Figure 6 As shown, this embodiment provides another linear LED driving circuit with a different structure, including the linear LED control chip in Embodiment 1, and also includes a rectifier bridge 7, a capacitor CAP, and a reference voltage generation unit 9. The positive output terminal of the rectifier bridge 7 is electrically connected to the anode of the diode D4. The cathode of the diode D4 is electrically connected to the HV pin and the positive terminal of the capacitor CAP, respectively. The negative terminal of the capacitor CAP is electrically connected to the CAP pin. The positive terminal of the capacitor CAP and the DRN_W pin are used to electrically connect to the two ends of the high color temperature LED branch 5. The positive terminal of the capacitor CAP and the DRN_Y pin are used to electrically connect to the two ends of the low color temperature LED branch 6. The CS_Y pin is grounded through the resistor RCY, and the CS_W pin is grounded through the resistor RCW. The reference voltage generation unit 9 is electrically connected to the CCT pin and is used to generate an adjustable reference voltage VREFW at the CCT pin. The GND pin is grounded.
[0044] More specifically, in this embodiment, the reference voltage generation unit 10 includes an MCU, resistors R1 and R2, and capacitor C1. Resistors R1 and R2 are connected in series to form a voltage divider branch. The voltage input from the MCU to resistor R2 is adjustable, thereby adjusting the voltage across resistor R1 and ultimately changing the voltage at the output terminal of the current source ICCT.
[0045] In one implementation, other existing voltage generation circuitry can be used to generate a reference voltage VREFW with an adjustable input voltage to the CCT pin.
[0046] Based on the above description and inspired by this utility model, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A linear LED control chip, comprising a first current control unit and a second current control unit, characterized in that, It also includes diodes D1, D2, and D3; The reference input terminal of the first current control unit and the reference input terminal of the second current control unit are respectively used to input reference voltages. The input terminal of the first current control unit is electrically connected to the cathode of diode D2; the input terminal of the second current control unit is electrically connected to the cathode of diode D3. The anodes of diode D3 and diode D2 are both electrically connected to the cathode of diode D1, and the anode of diode D1 is grounded.
2. The linear LED control chip according to claim 1, characterized in that, The first current control unit includes an operational amplifier EAW and a MOSFET QW, and the positive input terminal of the operational amplifier EAW is the reference input terminal of the first current control unit. The output terminal of the operational amplifier EAW is electrically connected to the gate of the MOSFET QW, the drain of the MOSFET QW is the input terminal of the first current control unit, and the source of the MOSFET QW is electrically connected to the negative input terminal of the operational amplifier EAW. The second current control unit includes an operational amplifier EAY and a MOSFET QY. The positive input terminal of the operational amplifier EAY is the reference input terminal of the second current control unit. The output terminal of operational amplifier EAY is electrically connected to the gate of MOSFET QY, the drain of MOSFET QY is the input terminal of the second current control unit, and the source of MOSFET QY is electrically connected to the negative input terminal of operational amplifier EAY.
3. A linear LED control chip according to claim 1, characterized in that, It also includes a power supply unit, a reference unit, a current source ICCT, and a reference voltage generation unit; The power supply unit generates a power supply voltage based on an external input voltage, and the reference unit generates a reference voltage VREF based on the power supply voltage. The current source ICCT generates operating current based on the power supply voltage, and the output terminal of the current source ICCT is electrically connected to the reference input terminal of the first current control unit. The reference voltage generation unit generates a reference voltage VREFY that is input to the reference input terminal of the second current control unit based on the reference voltage VREF and the voltage at the output terminal of the current source ICCT.
4. A linear LED control chip according to claim 3, characterized in that, The reference voltage generation unit generates a reference voltage VREFY based on the difference between the reference voltage VREF and the voltage at the output terminal of the current source ICCT.
5. A linear LED control chip according to claim 4, characterized in that, The reference voltage generating unit includes a voltage-controlled voltage source (VCVS). The positive input terminal of the VCVS is used to input the reference voltage VREF. The negative input terminal of the VCVS is electrically connected to the output terminal of the current source ICCT. The positive output terminal of the VCVS is used to output the reference voltage VREFY. The negative output terminal of the VCVS is grounded.
6. A linear LED control chip according to claim 3, characterized in that, The power supply unit includes a transistor JFET and a capacitor CVCC. The input terminal of the transistor JFET is used to input the external input voltage, and the output terminal of the transistor JFET is electrically connected to one end of the capacitor CVCC to output the power supply voltage. The other end of the capacitor CVCC is grounded.
7. A linear LED control chip according to any one of claims 3-6, characterized in that, The output terminal of the current source ICCT is also electrically connected to a clamping unit, which is used to clamp the voltage at the output terminal of the current source ICCT.
8. A linear LED control chip according to claim 7, characterized in that, It also includes the chip body, and the power supply unit, reference unit, current source ICCT, reference voltage generation unit, first current control unit, second current control unit, diode D1, diode D2, diode D3 and clamping unit are all disposed on the chip body; The chip body also has an HV pin, a CAP pin, a DRN_W pin, a DRN_Y pin, a CS_Y pin, a CS_W pin, a CCT pin, and a GND pin. The HV pin is electrically connected to the power supply unit and is used to input the external input voltage. The CAP pin is electrically connected to the cathode of diode D1. The DRN_W pin is electrically connected to the cathode of diode D2. The DRN_Y pin is electrically connected to the cathode of diode D3. The CS_Y pin is electrically connected to the output terminal of the second current control unit. The CS_W pin is electrically connected to the output terminal of the first current control unit. The CCT pin is electrically connected to the output terminal of the current source ICCT. The GND pin is electrically connected to all ground terminals of the chip.
9. A linear LED driving circuit, characterized in that, The linear LED control chip according to claim 8 further includes a rectifier bridge, a capacitor CAP, and a load unit. The positive output terminal of the rectifier bridge is electrically connected to the anode of diode D4. The cathode of diode D4 is electrically connected to the HV pin and the positive terminal of capacitor CAP. The negative terminal of capacitor CAP is electrically connected to the CAP pin. The positive terminal of capacitor CAP and the DRN_W pin are used to electrically connect to the two ends of the high color temperature LED branch. The positive terminal of capacitor CAP and the DRN_Y pin are used to electrically connect to the two ends of the low color temperature LED branch. The CS_Y pin is grounded through resistor RCY. The CS_W pin is grounded through resistor RCW. The CCT pin is grounded through the load unit. The load unit is used to provide an adjustable resistance load branch from the output terminal of current source ICCT to the ground terminal. The GND pin is grounded.
10. A linear LED driving circuit, characterized in that, The linear LED control chip according to claim 8 further includes a rectifier bridge, a capacitor CAP, and a reference voltage generation unit. The positive output terminal of the rectifier bridge is electrically connected to the anode of diode D4. The cathode of diode D4 is electrically connected to the HV pin and the positive terminal of capacitor CAP. The negative terminal of capacitor CAP is electrically connected to the CAP pin. The positive terminal of capacitor CAP and the DRN_W pin are used to electrically connect to the two ends of the high color temperature LED branch. The positive terminal of capacitor CAP and the DRN_Y pin are used to electrically connect to the two ends of the low color temperature LED branch. The CS_Y pin is grounded through resistor RCY, and the CS_W pin is grounded through resistor RCW. The reference voltage generation unit is electrically connected to the CCT pin and is used to generate an adjustable reference voltage VREFW at the CCT pin. The GND pin is grounded.