Linear LED control chip and drive circuit
By using a linear LED control chip and drive circuit with shared capacitors in the LED color adjustment linear drive circuit, the problem of excessive use of capacitors leading to large circuit volume in the existing technology is solved, and more compact and flexible color temperature control is achieved.
Patent Information
- Application Number
- CN202510978132.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-09-12
AI Technical Summary
The existing LED color adjustment linear drive circuit requires two large-value capacitors, which makes the circuit bulky and not compact enough.
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, and the reference voltage is adjusted through the reference unit, current source ICCT and voltage-controlled voltage source VCVS to achieve more flexible color temperature control.
The circuit structure and volume are simplified, richer color temperature control effects are achieved, the number of capacitors used is reduced, and the compactness of the circuit is improved.
Smart Images
Figure CN120640472A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of LED control, and in particular to a linear LED control chip and a drive circuit. Background Art
[0002] In LED lighting applications, linear color adjustment of the LED is often required to achieve smooth color transitions, accurately match scene requirements, and improve visual comfort.
[0003] The linear drive circuit used in the existing LED color adjustment linear drive circuit application scenario is as follows: Figure 1 As shown in the figure, the main power of the circuit is divided into two independent LED branches, one is the high color temperature branch LEDW, and the other is the low color temperature branch LEDY, where the rated operating voltage of the LEDs is the same. Figure 1 The circuit shown operates as follows: The input AC voltage VIN is rectified into a pulsating bus voltage after passing through the rectifier bridge. The bus voltage is recorded as VBUS. When VBUS is lower than the startup voltage VLED of the load LED, the load LED does not work. When VBUS is higher than the startup voltage VLED, the two current control modules start working, and VBUS flows through the load LED and the MOS transistors 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, RCWX and RCYX are RCW2 and RCY2 respectively. If it is in the left gear, it is RCW1 and RCS1. If it is in the right gear, it is RCW3 and RCY3. In addition, since the input AC voltage is undervoltage relative to the load LED, the current passing through the LED is ILEDX=VREF / RCWX*( T LED_WORK / T LINE ). Where T LED_WORK T is the time during which VBUS is greater than the LED operating voltage within the power frequency cycle. LINE is the power frequency period of the power grid.
[0004] exist Figure 1 The function of capacitor CAP is to filter the current flowing through the LED to smooth the output current. At the same time, different resistance combinations are achieved by controlling the unit of the dip switch SW, thereby generating different high color temperature and low color temperature currents, and finally achieving the effect of mixing high and low color temperatures.
[0005] for Figure 1In the circuit shown, because the power of the two LED branches is independent, their ratio is controlled entirely by the resistance values of RCWX and RCYX to control the mixing ratio of high and low color temperatures. To meet performance requirements in all situations, when only high or low color temperature is required, the load LED in one LED branch is inoperative. Therefore, the load LED in the other LED branch must pass the entire current to meet the power requirement. Therefore, the capacitor CAP must be designed according to the current ripple requirements required for the load LED in one LED branch to pass the entire full power in the extreme case. Therefore, the dimming solution requires a capacitor CAP for each high and low color temperature to meet the requirements for the full current flowing through the LEDs in one branch. Therefore, existing color-adjusting linear LED drive circuits must use two capacitors CAP, which are bulky and have high capacitance requirements. Summary of the Invention In view of the shortcomings of the background technology, the present invention provides a linear LED control chip and drive circuit. The technical problem to be solved is that when the existing LED is driven linearly for color adjustment, two large-capacitance capacitors are required for output filtering, resulting in a large circuit volume.
[0006] To solve the above technical problems, in a first aspect, the present invention provides the following technical solutions: a linear LED control chip, comprising a first current control unit, a second current control unit, a diode D1, a diode D2 and a 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 a reference voltage, and the input terminal of the first current control unit is electrically connected to the cathode of the diode D2; the input terminal of the second current control unit is electrically connected to the cathode of the diode D3, and the anode of the diode D3 and the anode of the diode D2 are both electrically connected to the cathode of the diode D1, and the anode of the diode D1 is grounded.
[0007] In a certain embodiment of the first aspect, the first current control unit includes an operational amplifier EAW and a MOS transistor 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 MOS transistor QW, the drain of the MOS transistor QW is the input terminal of the first current control unit, and the source of the MOS transistor 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 MOS transistor QY, and the positive input terminal of the operational amplifier EAY is the reference input terminal of the second current control unit; The output end of the operational amplifier EAY is electrically connected to the gate of the MOS transistor QY, the drain of the MOS transistor QY is the input end of the second current control unit, and the source of the MOS transistor QY is electrically connected to the negative input end of the operational amplifier EAY.
[0008] In certain embodiments of the first aspect, the present invention further includes a power supply unit, a reference unit, a current source ICCT, and a reference voltage generating 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 end of the current source ICCT is electrically connected to the reference input end of the first current control unit; the reference voltage generating unit generates a reference voltage VREFY input to the reference input end of the second current control unit based on the reference voltage VREF and the voltage at the output end of the current source ICCT.
[0009] In some implementations of the first aspect, the reference voltage generating unit generates the reference voltage VREFY based on a difference between the reference voltage VREF and a voltage at an output terminal of the current source ICCT.
[0010] In a certain embodiment of the first aspect, the reference voltage generating unit includes a voltage-controlled voltage source VCVS, a positive input terminal of the voltage-controlled voltage source VCVS is used to input the reference voltage VREF, a negative input terminal of the voltage-controlled voltage source VCVS is electrically connected to the output terminal of the current source ICCT, a positive output terminal of the voltage-controlled voltage source VCVS is used to output the reference voltage VREFY, and a negative output terminal of the voltage-controlled voltage source VCVS is grounded.
[0011] In a certain embodiment of the first aspect, the power supply unit includes a transistor JFET and a capacitor CVCC, the input end of the transistor JFET is used to input the external input voltage, the output end of the transistor JFET is electrically connected to one end of the capacitor CVCC for outputting the power supply voltage, and the other end of the capacitor CVCC is grounded.
[0012] In a certain embodiment of the first aspect, the output end of the current source ICCT is further electrically connected to a clamping unit, and the clamping unit is used to clamp the voltage of the output end of the current source ICCT.
[0013] In a certain embodiment of the first aspect, the present invention further includes a chip body, and the power supply unit, the reference unit, the current source ICCT, the reference voltage generating unit, the first current control unit, the second current control unit, the diode D1, the diode D2, the diode D3 and the clamping unit are all disposed on the chip body; The chip body is also provided with 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 the diode D1, the DRN_W pin is electrically connected to the cathode of the diode D2, the DRN_Y pin is electrically connected to the cathode of the diode D3, the CS_Y pin is electrically connected to the output end of the second current control unit, the CS_W pin is electrically connected to the output end of the first current control unit, the CCT pin is electrically connected to the output end of the current source ICCT, and the GND pin is electrically connected to all ground ends of the chip.
[0014] The second invention provides a linear LED driving circuit, including the above-mentioned linear LED control chip, and also including a rectifier bridge, a capacitor CAP and a load unit, the positive output end of the rectifier bridge 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 end of the capacitor CAP respectively, the negative end of the capacitor CAP is electrically connected to the CAP pin, the positive end 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, the positive end 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, the CS_Y pin is grounded through the resistor RCY, the CS_W pin is grounded through the resistor RCW, the CCT pin is grounded through the load unit, the load unit is used to provide a load branch with adjustable resistance from the output end of the current source ICCT to the ground end, and the GND pin is grounded.
[0015] In a third aspect, the present invention provides a linear LED drive circuit of another structure, comprising the above-mentioned linear LED control chip, and also comprising a rectifier bridge, a capacitor CAP, and a reference voltage generating unit, wherein the positive output end of the rectifier bridge 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 end of the capacitor CAP, respectively, the negative end of the capacitor CAP is electrically connected to the CAP pin, the positive end 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, the positive end 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, the CS_Y pin is grounded via a resistor RCY, the CS_W pin is grounded via a resistor RCW, the reference voltage generating unit is electrically connected to the CCT pin, and is used to generate a reference voltage VREFW with an adjustable voltage at the CCT pin, and the GND pin is grounded.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The control chip of the present invention is provided with diodes D1, D2, and D3. Thus, the first current control unit and the second current control unit can share a capacitor CAP when actually controlling the currents of the high color temperature LED branch and the low color temperature LED branch, thereby simplifying the circuit structure and volume. Second, by providing a reference unit, a current source ICCT, and a voltage-controlled voltage source VCVS, a load branch with adjustable resistance or a reference voltage generating unit with adjustable output voltage is provided at the CCT pin. This allows the voltage input to the reference input terminals of the first current control unit and the second current control unit to be varied. Compared to varying the resistance value via a DIP switch, the present invention enables more possible color temperature control. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 The following is a circuit diagram of an existing linear LED driving circuit with adjustable color temperature; Figure 2 This is a schematic diagram of the structure of the control chip in Example 1; Figure 3 is a circuit diagram of the linear LED driving circuit in Example 2; Figure 4 for Figure 3 Simulation waveforms of current ILEDW and current ILEDY during circuit simulation; Figure 5 for Figure 3 Power waveform of the input power AC during circuit simulation; Figure 6 This is a circuit diagram of the linear LED driving circuit in Example 2. DETAILED DESCRIPTION
[0018] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.
[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, a diode D1, a diode D2 and a 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 the diode D2; the input terminal of the second current control unit 3 is electrically connected to the cathode of the diode D3, and the anode of the diode D3 and the anode of the diode D2 are both electrically connected to the cathode of the diode D1, and the anode of the diode D1 is grounded.
[0020] In actual use, the cathode of the diode D1 is used to connect to the capacitor CAP. The control chip in this embodiment is provided with the diode D1, the diode D2 and the diode D3, so that the first current control unit 2 and the second current control unit 3 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 volume; in addition, the principle of realizing the sharing of a capacitor CAP is explained in the second embodiment and will not be described again here.
[0021] In this embodiment, Figure 2 In the embodiment, the first current control unit 2 includes an operational amplifier EAW and a MOS transistor QW, and the positive input terminal of the 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 MOS transistor QW, the drain of the MOS transistor QW is the input terminal of the first current control unit 2, and the source of the MOS transistor QW is electrically connected to the negative input terminal of the operational amplifier EAW.
[0022] In this embodiment, Figure 2 In the embodiment, the second current control unit 3 includes an operational amplifier EAY and a MOS transistor QY, and the positive input terminal of the 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 MOS transistor QY, the drain of the MOS transistor QY is the input terminal of the second current control unit 3, and the source of the MOS transistor 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 input to a reference voltage generating circuit with an adjustable voltage value as follows: exist Figure 2 In the present invention, the present invention further includes a power supply unit 1, a reference unit, a current source ICCT and a reference voltage generating unit 10; The power supply unit 1 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 end of the current source ICCT is electrically connected to the reference input end of the first current control unit 2; the reference voltage generating unit 10 generates a reference voltage VREFY input to the reference input end of the second current control unit 3 based on the reference voltage VREF and the voltage at the output end of the current source ICCT. More specifically, the reference voltage generating unit 10 generates the reference voltage VREFY based on a difference between the reference voltage VREF and the voltage at the output terminal of the current source ICCT.
[0024] exist Figure 2 In the figure, the reference voltage generating unit 10 includes a voltage-controlled voltage source VCVS, a positive input terminal of the voltage-controlled voltage source VCVS is used to input a reference voltage VREF, a negative input terminal of the voltage-controlled voltage source VCVS is electrically connected to the output terminal of the current source ICCT, a positive output terminal of the voltage-controlled voltage source VCVS is used to output a reference voltage VREFY, and a negative output terminal of the voltage-controlled voltage source VCVS is grounded.
[0025] In actual 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 VCVC also changes, thereby changing the magnitude of the reference voltage input to the reference input terminal of the first current control unit 2 and the reference input terminal of 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, then 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 geometric proportion.
[0026] In some implementations, other circuits may be used to proportionally amplify or proportionally reduce the difference between the reference voltage VREF and the voltage at the output terminal of the current source ICCT to generate an adjustable reference voltage VREFY.
[0027] Specifically, in this embodiment, Figure 2 In the figure, the power supply unit 1 includes a transistor JFET and a capacitor CVCC, the input end of the transistor JFET is used to input an external input voltage, the output end of the transistor JFET is electrically connected to one end of the capacitor CVCC for outputting a power supply voltage, and the other end of the capacitor CVCC is grounded.
[0028] Specifically, in this embodiment, Figure 2 In the embodiment, the output end of the current source ICCT is further electrically connected to a clamping unit 4, which is used to clamp the voltage at the output end of the current source ICCT to prevent the voltage at the output end 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, a cathode of the Zener diode ZD is electrically connected to the output end of the current source ICCT, and an anode of the Zener diode ZD is grounded.
[0030] In a certain implementation manner, those skilled in the art may clamp the voltage at the output end of the current source ICCT according to other existing clamping circuit structures.
[0031] Specifically, in this embodiment, the present invention further includes a chip body, on which the power supply unit 1, the reference unit, the current source ICCT, the reference voltage generating 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 arranged; The chip body is also provided with 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 1 for inputting an external input voltage. The CAP pin is electrically connected to the cathode of the diode D1, the DRN_W pin is electrically connected to the cathode of the diode D2, the DRN_Y pin is electrically connected to the cathode of the diode D3, the CS_Y pin is electrically connected to the output end of the second current control unit 3, the CS_W pin is electrically connected to the output end of the first current control unit 2, the CCT pin is electrically connected to the output end of the current source ICCT, and the GND pin is electrically connected to all ground ends 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 Example 1, and also including 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 a load branch with adjustable resistance from the output terminal of the current source ICCT to the ground terminal, and the GND pin is grounded.
[0033] Specifically, in this embodiment, the load unit 8 includes a sliding rheostat RCT and a capacitor CCT, the sliding rheostat RCT and the capacitor CCT 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 value 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 achieving adjustable reference voltage input to the first current control unit 2 and the second current control unit 3.
[0034] In some embodiments, the load unit 8 may further include a programmable digital potentiometer, which is controlled by the controller to adjust the resistance between one end of the programmable digital potentiometer electrically connected to the output end of the current source ICCT and the ground end.
[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 the rectifier bridge 7 is recorded as voltage VBUS, and the voltage at which the high color temperature LED branch 5 and the low color temperature LED branch 6 start working is recorded as voltage VLED; When 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 operating voltage, the reference unit outputs the corresponding reference voltage VREF; When the voltage VBUS is lower 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 higher than the voltage VLED, the first current control unit 2 and the second current control unit 3 start working, and the voltage VBUS flows into the MOS transistor QW and the MOS transistor QY respectively through the high color temperature LED branch 5 and the low color temperature LED branch 6, and the current flowing through is controlled at VREF / RCW and VREF / RCY.
[0036] Obviously, due to the VBUS undervoltage, 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 MOS transistors QW and QY. When the VBUS undervoltage is not present, the excess current flowing through the high-color-temperature LED branch 5 and the low-color-temperature LED branch 6 passes through capacitor CAP.
[0037] In this embodiment, diodes D2 and D3 separate the high color temperature LED branch 5 from the low color temperature LED branch 6. Current flowing through the high color temperature LED branch 5 can only flow through the MOS transistor; conversely, current flowing through the low color temperature LED branch 6 can only flow through the MOS transistor QY. However, when the current flowing through the MOS transistor QW exceeds the current flowing through the high color temperature LED branch 5 and the current flowing through the MOS transistor QY exceeds the current flowing through the low color temperature LED branch 6, the excess current can be shared by the storage capacitor CAP.
[0038] When VBUS is undervoltage, capacitor CAP powers both high-color-temperature LED branch 5 and low-color-temperature LED branch 6. Since capacitor CAP's power supply to high-color-temperature LED branch 5 and low-color-temperature LED branch 6 does not meet the current requirements for MOS transistors QW and QY, respectively, and the current flowing through them falls short of VREF / RCW and VREF / RCY, MOS transistors QW and QY are fully 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 MOS transistors QW and QY, then through resistors RCW and RCY, and finally through diode D1 back to capacitor CAP.
[0039] The current from current source ICCT flows through the external resistor RCCT connected to the CCT pin, generating a voltage denoted as VREFW. Capacitor CCT helps stabilize the voltage at the CCT pin. The maximum voltage at the CCT pin is limited by Zener diode ZD and can be designed to be equal to VREF. The difference between VREF and VREFW is denoted as VREFY. Clearly, the equation VREFW + VREFY = VREF 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, which is used to change the current distribution of the MOS tube QW and the MOS tube QY, but the total current remains unchanged. In addition, the ratio of high and low color temperatures is changed while keeping the power unchanged to produce a color temperature adjustment effect.
[0041] right Figure 3 The circuit shown in the figure is simulated by EDA. The reference voltage VREF is set to 0.5V, the resistors RCW and RCSY are set to 4Ω, the voltage of the input power supply AC is set to 120V, the rated voltage of the 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 ILEDW and ILEDY are equal at the beginning. After the reference voltage VREFW gradually increases, ILEDW and ILEDY increase and decrease respectively.
[0042] The input power waveform of the input power AC is as follows Figure 5 As shown, after stabilization, there is no significant change. Simulation data shows that when ILEDW = ILEDY, the input power is approximately the maximum ILEDW, while when ILEDY = 0, the temperature rise input power is 1.05 times. When VREFW changes from VREF / 2 to 0, the LEDW and LEDY currents change interchangeably, while the input power changes in unison.
[0043] Example 3 like Figure 6 As shown, this embodiment provides a linear LED driving circuit with another structure, including the linear LED control chip of the first embodiment, and also including a rectifier bridge 7, a capacitor CAP and a reference voltage generating 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 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 the two ends of the low color temperature LED branch 6, the CS_Y pin is grounded via a resistor RCY, the CS_W pin is grounded via a resistor RCW, the reference voltage generating unit 10 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 generating unit 10 includes an MCU, a resistor R1, a resistor R2, and a capacitor C1. The resistors R1 and R2 are connected in series to form a voltage divider branch. The voltage input from the MCU to the resistor R2 is adjustable, thereby adjusting the voltage on the resistor R1, and ultimately changing the voltage at the output end of the current source ICCT.
[0045] In some implementations, other existing voltage generation circuits may be used to generate a reference voltage VREFW with an adjustable voltage input to the CCT pin.
[0046] The above description is for inspiration. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the content 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: Also included are 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 a reference voltage, and the input terminal of the first current control unit is electrically connected to the cathode of the diode D2; the input terminal of the second current control unit is electrically connected to the cathode of the diode D3, and the anode of the diode D3 and the anode of the diode D2 are both electrically connected to the cathode of the diode D1, and the anode of the 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 MOS transistor 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 MOS transistor QW, the drain of the MOS transistor QW is the input terminal of the first current control unit, and the source of the MOS transistor 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 MOS transistor QY, and the positive input terminal of the operational amplifier EAY is the reference input terminal of the second current control unit; The output end of the operational amplifier EAY is electrically connected to the gate of the MOS transistor QY, the drain of the MOS transistor QY is the input end of the second current control unit, and the source of the MOS transistor QY is electrically connected to the negative input end of the operational amplifier EAY.
3. The 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 generating 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 an output terminal of the current source ICCT is electrically connected to a reference input terminal of the first current control unit; The reference voltage generating unit generates a reference voltage VREFY input to a reference input terminal of the second current control unit based on the reference voltage VREF and a voltage of an output terminal of the current source ICCT.
4. The linear LED control chip according to claim 3, characterized in that: The reference voltage generating unit generates a reference voltage VREFY based on a difference between the reference voltage VREF and a voltage at an output terminal of the current source ICCT.
5. The linear LED control chip according to claim 4, characterized in that: The reference voltage generating unit includes a voltage-controlled voltage source VCVS, wherein a positive input terminal of the voltage-controlled voltage source VCVS is used to input the reference voltage VREF, a negative input terminal of the voltage-controlled voltage source VCVS is electrically connected to the output terminal of the current source ICCT, a positive output terminal of the voltage-controlled voltage source VCVS is used to output the reference voltage VREFY, and a negative output terminal of the voltage-controlled voltage source VCVS is grounded.
6. The 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 end of the transistor JFET is used to input the external input voltage, the output end of the transistor JFET is electrically connected to one end of the capacitor CVCC for outputting the power supply voltage, and the other end of the capacitor CVCC is grounded.
7. A linear LED control chip according to any one of claims 3 to 6, characterized in that: The output end of the current source ICCT is further electrically connected to a clamping unit, and the clamping unit is used to clamp the voltage of the output end of the current source ICCT.
8. The linear LED control chip according to claim 7, characterized in that: It also includes a chip body, on which the power supply unit, the reference unit, the current source ICCT, the reference voltage generating unit, the first current control unit, the second current control unit, the diode D1, the diode D2, the diode D3 and the clamping unit are all arranged; The chip body is also provided with 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 the diode D1, the DRN_W pin is electrically connected to the cathode of the diode D2, the DRN_Y pin is electrically connected to the cathode of the diode D3, the CS_Y pin is electrically connected to the output end of the second current control unit, the CS_W pin is electrically connected to the output end of the first current control unit, the CCT pin is electrically connected to the output end of the current source ICCT, and the GND pin is electrically connected to all ground ends of the chip.
9. A linear LED driving circuit, characterized in that: The linear LED control chip includes the linear LED control chip according to claim 8, and further includes a rectifier bridge, a capacitor CAP, and a load unit, wherein the positive output terminal of the rectifier bridge 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, 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, the CS_Y pin is grounded through a resistor RCY, the CS_W pin is grounded through a resistor RCW, the CCT pin is grounded through the load unit, the load unit is used to provide a load branch with adjustable resistance from the output terminal of the current source ICCT to the ground terminal, and the GND pin is grounded.
10. A linear LED driving circuit, characterized in that: The linear LED control chip includes the linear LED control chip according to claim 8, and further includes a rectifier bridge, a capacitor CAP and a reference voltage generating unit, wherein the positive output terminal of the rectifier bridge 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, 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, the CS_Y pin is grounded through the resistor RCY, the CS_W pin is grounded through the resistor RCW, the reference voltage generating unit is electrically connected to the CCT pin, and is used to generate a reference voltage VREFW with an adjustable voltage at the CCT pin, and the GND pin is grounded.