A control circuit and LED power supply device for LED power supply

Abstract

A control circuit and LED power supply device for powering LEDs are disclosed. The control circuit includes: a first current source module configured to output a first current positively correlated with the LED temperature; a second current source module configured to output a second current unaffected by the LED temperature; a slope current mirror module connected to the first current source module, configured to mirror the first current according to a first preset ratio to generate a first mirrored current; and a control current module connected to the second current source module and the slope current mirror module, configured to receive the second current and the first mirrored current, and output a control current based on the difference between the second current and the first mirrored current, wherein the operating current for powering the LED is based on the control current. This control circuit provides more reliable and stable dynamic temperature protection for the LED.

Description

Technical Field

[0001] This invention relates to the field of circuits, and more particularly to a control circuit and LED power supply device for LED power supply. Background Technology

[0002] With the development of electronic products such as televisions, monitors, and mobile devices, the application of light-emitting diodes (LEDs) in display devices of various electronic products has become a mainstream trend. To prevent LEDs from overheating and damaging the devices, traditional LED control systems typically have an over-temperature protection mechanism that directly cuts off the power supply to the LED when its temperature reaches the over-temperature point. However, due to variations in manufacturing processes, different components and circuit configurations can cause differences in LED temperature performance. Over-temperature protection mechanisms with fixed over-temperature points are difficult to achieve stable and reliable protection. The over-temperature point may be too low, causing the LED to shut off prematurely and resulting in a black screen, or too high, causing the LED to fail to shut off in time and damage the device. This results in unsatisfactory over-temperature protection and a poor user experience. Summary of the Invention

[0003] A control circuit for powering an LED according to an embodiment of the present invention includes: a first current source module configured to output a first current positively correlated with the temperature of the LED; a second current source module configured to output a second current unaffected by the temperature of the LED; a slope current mirror module connected to the first current source module and configured to mirror the first current according to a first preset ratio to generate a first mirror current; and a control current module connected to the second current source module and the slope current mirror module and configured to receive the second current and the first mirror current, and output a control current based on the difference current between the second current and the first mirror current, wherein the operating current for powering the LED is based on the control current.

[0004] According to an embodiment of the present invention, an LED power supply device includes: the control circuit for supplying power to an LED as described above; and a current output module connected to the control circuit, configured to receive a control current output by the control circuit and output a corresponding operating current to supply power to the LED based on the control current. Attached Figure Description

[0005] The invention can be better understood from the following description of specific embodiments of the invention in conjunction with the accompanying drawings, wherein:

[0006] Figure 1 A schematic diagram of the logic structure of a control circuit for LED power supply according to an embodiment of the present invention is shown;

[0007] Figure 2 It shows Figure 1 The circuit structure diagram shown is an example implementation of the control circuit for LED power supply.

[0008] Figure 3 A temperature-based current curve is shown according to an embodiment of the present invention;

[0009] Figure 4 It shows Figure 1 The diagram shows another example of a control circuit implemented for LED power supply.

[0010] Figure 5 It shows Figure 2 and Figure 4 The circuit structure diagram of an example implementation of the first current source unit is shown.

[0011] Figure 6 A schematic diagram of the circuit structure of an LED power supply device according to an embodiment of the present invention is shown. Detailed Implementation

[0012] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific configurations and algorithms presented below, but covers any modifications, substitutions, and improvements to elements, components, and algorithms without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description in order to avoid unnecessarily obscuring the invention.

[0013] Considering that different LED processing techniques make it difficult for over-temperature protection mechanisms with fixed over-temperature points to achieve stable and reliable protection during LED power supply, a control circuit and LED power supply device for LED power supply according to embodiments of the present invention are proposed. This can reduce the heat generation power of the LED, enable the LED to operate in a controllable thermal steady state, achieve more reliable and stable temperature protection, and reduce the probability of LED black screen or overheating causing device damage.

[0014] Figure 1 A schematic diagram of the logic structure of a control circuit for LED power supply according to an embodiment of the present invention is shown. Figure 1 As shown, the control circuit 10 for powering the LED includes: a first current source module 11 configured to output a first current I1 that is positively correlated with the temperature of the LED; a second current source module 12 configured to output a second current I2 that is unaffected by the temperature of the LED; and a slope current mirror module 13 connected to the first current source module 11, configured to mirror the first current I1 according to a first preset ratio K1 to generate a first mirrored current I1. ′; and a control current module 14, connected to the second current source module 12 and the slope current mirror module 13, configured to receive the second current I2 and the first mirror current I1. ′ Based on the second current I2 and the first mirror current I1 ′ The differential current I3 outputs the control current I. C Among them, the operating current I for powering the LED w Based on control current I C .

[0015] exist Figure 1 In the control circuit 10 shown, the calculation process for the differential current I3 includes:

[0016] I1 ′ =K1×I1;

[0017] I3 = I2 - I1 ′ ;

[0018] I3 = I2 - K1 × I1.

[0019] Based on control current I C Generates operating current I w and using the operating current I w When the LED is powered, it generates heat during operation, causing its temperature to rise. Since the first current I1 is positively correlated with the LED's temperature, as the LED's temperature increases, the first current I1 increases, and the control current I... c The decrease causes the operating current I to decrease. w This reduces the heat generation power and heating rate of the LED, allowing it to operate in a controllable thermal steady state.

[0020] Compared to the solution of directly cutting off power supply when the temperature rises to the overheating point, Figure 1 The control circuit 10 shown can dynamically control the operating current I based on temperature. w Before the LED temperature rises to the over-temperature point, the control current I is reduced. c To reduce operating current I w This reduces the rate of LED heating up and slows down the temperature rise process, decreasing the probability of the LED temperature rising to the over-temperature point. It also reduces the probability of the LED suddenly shutting down, blacking out, or being burned out when it reaches the over-temperature point, providing more reliable and stable dynamic temperature protection for the LED. This results in longer LED operating time and lifespan, and an improved user experience.

[0021] Figure 2 It shows Figure 1 The diagram shows an example implementation of a control circuit for LED power supply. Figure 2As shown, in some embodiments, the first current source module 11 includes a first current source unit Iptat and a second current source unit Itha connected sequentially between a first preset power supply VDD and a ground point, wherein: the first current source unit Iptat is configured to output a real-time temperature current I that is positively correlated with the temperature of the LED. ptat The second current source unit Itha is configured to output a reference temperature current I that is unaffected by the temperature of the LED. tha The node between the first current source unit Iptat and the second current source unit Itha is used to output the real-time temperature current I. ptat With reference temperature current I tha The difference current is taken as the first current I1, therefore:

[0022] I1=I ptat -I tha .

[0023] Based on the circuit connection relationship between the first current source unit Iptat and the second current source unit Itha, the real-time temperature current I... ptat Current I greater than the reference temperature tha At that time, the first current source module 11 outputs a first current I1 greater than zero, and the first current I1 increases with temperature; at the real-time temperature current I... ptat Not greater than the reference temperature current I tha At this time, the first current source module 11 will not output current. Therefore, the first current I1 = 0, and I3 = I2 - K1 × I1 = I2. Since the control current I... c Based on the differential current I3 and the fact that the second current I2 is not affected by the LED temperature, the control current I is... c Unaffected by LED temperature. Real-time temperature-current I... ptat Not greater than the reference temperature current I tha At that time, the first current I1 is zero, and the real-time temperature current I... ptat Current I greater than the reference temperature tha At that time, the first current I1 is greater than zero and increases with temperature.

[0024] Based on the above analysis, it can be concluded that the reference temperature current I... tha It can be used to set the control current I c The inflection point of the change with temperature, and the real-time temperature current I are known. ptat Positively correlated with temperature, assuming real-time temperature current I ptat (T) is the reference temperature current I at temperature T=T0. tha , that is I ptat (T0)=I tha At this time, the curve of the differential current I3 changing with temperature is as follows: Figure 3As shown, when the temperature is not greater than T0, I3 = I2. After the temperature exceeds T0, the differential current I3 gradually decreases with increasing temperature. Temperature T0 is the inflection point of the differential current I3. Since the control current I... c Based on the differential current I3, the temperature T0 is also determined by the control current I. c The turning point of change. Figure 3 It is assumed that the real-time temperature current I tha An example of the variation curve of the time difference current I3 that is linearly positively correlated with temperature, if the real-time temperature current I ptat The positive correlation with temperature, even for other non-linear changes, exhibits the same pattern described above. That is, when the LED temperature is not above the inflection point, the control current I... c Keeping the current constant, once the LED temperature exceeds the inflection point, the control current I... c It decreases as temperature rises.

[0025] like Figure 2 As shown, in some embodiments, the slope current mirror module 13 includes a first current mirror unit 131 and a second current mirror unit 132, wherein: the first current mirror unit 131 includes a first control transistor M10 and a first controlled transistor M11, the first end of the first control transistor M10 is connected to the control terminal of the first control transistor M10, the control terminal of the first controlled transistor M11 and the first current source module 11, the second end of the first control transistor M10 is grounded to the second end of the first controlled transistor M11, and the first end of the first controlled transistor M11 serves as the output terminal of the first current mirror unit 131; the second current mirror unit 132 includes a second control transistor M20 and a second controlled transistor M21, the first end of the second control transistor M20 and the first end of the second controlled transistor M21 are connected to a first preset power supply VDD, the control terminal of the second control transistor M20 is connected to the second end of the second control transistor M20, the control terminal of the second controlled transistor M21 and the output terminal of the first current mirror unit 131, and the second end of the second controlled transistor M21 serves as the output terminal of the second current mirror unit 132 for outputting the first mirror current I1. ′ The current mirror ratio between the first control transistor M10 and the first controlled transistor M11 is the first unit ratio k1, and the current mirror ratio between the second control transistor M20 and the second controlled transistor M21 is the second unit ratio k2. The first preset ratio K1 is the product of the first unit ratio k1 and the second unit ratio k2 (i.e., K1 = k1 × k2).

[0026] For example, the first current mirror unit 131 mirrors the first current I1 according to the first unit ratio k1 to obtain the intermediate current I. 10 The second current mirror unit 132 mirrors the intermediate current I according to the second unit ratio k2. 10 To generate the first mirror current I1 ′ Thus, the slope current mirror module 13 generates and outputs the first mirror current I1.′ The derivation process is as follows:

[0027] I 10 =k1×I1;

[0028] I1 ′ =k2×I 10 ;

[0029] I1 ′ = k1×k2×I1.

[0030] like Figure 2 As shown, in some embodiments, the control current module 14 includes a third control transistor M30 and a third controlled transistor M31. The first end of the third control transistor M30 and the first end of the third controlled transistor M31 are connected to a first preset power supply VDD. The second end of the third control transistor M30 is connected to the control terminal of the third control transistor M30, the control terminal of the third controlled transistor M31, the slope current mirror module 13, and the second current source module 12. The second end of the third controlled transistor M31 serves as the output terminal of the control current module 14 for outputting control current.

[0031] like Figure 2 As shown, the second current source module 12 is connected between the control current module 14 and the ground terminal. The second current I2 flows from the control current module 14 to the ground terminal inside the second current source module 12. Based on the connection relationship between the third control transistor M30, the slope current mirror module 13, and the second current source module 12, the current flowing through the third control transistor M30 is the difference between the second current and the first mirror current, I3 = I2 - I1. ′ The third controlled transistor M31 is used to mirror the current flowing through the third control transistor M30 to generate a control current. At this time, we have: I C =k3×I3=k3×(I2-K1×I1), where, I C To control the current, k3 is the mirror image ratio between the third control transistor M30 and the third controlled transistor M31. Since the first current I1 is positively correlated with the LED temperature, as the LED temperature increases, the first current I1 increases, and the control current I... C Reduce the operating current I for powering the LED. w The corresponding reduction results in a decrease in the heat generation power of the LED.

[0032] Figure 4 It shows Figure 1 The diagram shows another example of a control circuit implemented for LED power supply. Figure 4 and Figure 2 The relationships between the existing modules are the same. For example... Figure 4As shown, in some embodiments, the number of first current source units is one or more, the number of second current source units is one or more, and the first current source module further includes a first switch. The first switch is connected to one of the first current source units and the second current source units and is configured to cut off or connect the current path of the connected first current source unit or the second current source unit. When there are multiple first current source units or second current source units, multiple first current source units are connected in parallel, and multiple second current source units are connected in parallel. The number of first switches is not limited and can be one or more. Each first switch can be connected to a first current source unit or a second current source unit and is configured to cut off or connect the current path of the connected unit.

[0033] For example, such as Figure 4 As shown, there is one first current source unit, m second current source units (denoted as Itha1-Itham, where m is an integer greater than 1), and m first switches (denoted as S11-S1m). Each first switch is connected between a common node and a second current source unit and is used to cut off or connect the current path of the connected second current source unit. The common node refers to the node between the first and second current source units. When the first switch S11 is closed, the current path of the second current source unit Itha1 is connected. Except for... Figure 4 In addition to the example, the first switch configured to cut off or connect the current path of the second current source unit can also be located between the second current source unit and the ground terminal; the first switch configured to cut off or connect the current path of the first current source unit can be located between the first preset power supply and the first current source unit, or between the first current source unit and the common node. The difference between the real-time temperature current output by the common node connecting all the first current source units and all the second current source units and the reference temperature current is used as the first current. The real-time temperature current includes all the output currents of the first current source units whose current paths are connected, and the reference temperature current includes all the output currents of the second current source units whose current paths are connected. By setting the state of the first switch to closed or open, the current path of the first current source unit or the second current source unit connected to it can be cut off or connected, thereby adjusting the specific magnitude relationship between the real-time temperature current and the reference temperature current, i.e., adjusting... Figure 3 The inflection point T0 in the curve of change.

[0034] like Figure 4 As shown, in some embodiments, there are multiple first controlled transistors connected in parallel. The first current mirror unit also includes a second switch, which is connected to any one of the first controlled transistors and configured to cut off or connect the current path of the first controlled transistor connected thereto. The first unit ratio is the current mirror ratio of the first control transistor and the first controlled transistor with the current path connected.

[0035] For example, such as Figure 4 As shown, there are n first controlled transistors (denoted as M11-M1n, where n is an integer greater than 1), and n second switches (denoted as S21-S2n). Each second switch is connected to a first controlled transistor and configured to cut off or open the current path of the connected first controlled transistor. In some examples, the second switch can be connected between the first terminal of the first controlled transistor and the second terminal of the second controlled transistor, or between the second terminal of the first controlled transistor and the ground terminal. In the first current mirror unit 131, each first controlled transistor with a current path can mirror the current of the first controlled transistor to generate a corresponding mirrored current. The intermediate current I output by the first current mirror unit 131 is... 10 This includes the mirror current of the first controlled transistor, which conducts all current paths. By setting the state of the second switch to closed or open, the current path of the first controlled transistor connected to it can be cut off or connected, thereby adjusting the first unit ratio k1 of the first current mirror unit and the first preset ratio K1 of the slope current mirror module. According to the current relationship in the control circuit, the adjustment of the first preset ratio actually adjusts the... Figure 3 The decreasing slope in the middle.

[0036] like Figure 4 As shown, in some embodiments, the control current module 14 may further include an over-temperature protection transistor M32, wherein the first end of the over-temperature protection transistor M32 is connected to the first preset power supply VDD, the control end of the over-temperature protection transistor M32 is connected to the control end of the third control transistor M30, and the second end of the over-temperature protection transistor M32 outputs an over-temperature protection current I. otp Here, the over-temperature protection transistor M32 and the third control transistor M30 form a pair of current mirrors. The over-temperature protection transistor M32 mirrors the current I3 to generate the over-temperature protection current.

[0037] like Figure 4 As shown, in some embodiments, the control circuit further includes an over-temperature protection flag module 15 connected to the control current module 14, configured to receive an over-temperature protection current I. otp In the over-temperature protection current I otpWhen the current is less than the preset current Iref, an over-temperature protection flag signal is output. For example, the over-temperature protection flag module 15 includes a comparator comp1, a reference resistor Rref, and an action switch M_t, wherein: the over-temperature protection transistor M32 and the reference resistor Rref are connected in series; the first input terminal of the comparator comp1 is connected to the over-temperature reference potential Vref; the second input terminal of the comparator comp1 is connected to the node between the over-temperature protection transistor M32 and the reference resistor Rref; and the output terminal of the comparator comp1 is connected to the control terminal of the action switch M_t to control the action switch M_t to output the over-temperature protection flag signal. The two input terminals of the comparator comp1 are the non-inverting input terminal and the inverting input terminal, respectively. One input terminal is used as the first input terminal, and the other input terminal is used as the second input terminal, as shown below. Figure 4 In the example shown, the first input terminal is the non-inverting input terminal, the second input terminal is the inverting input terminal, and the other end of the reference resistor Rref that is not connected to the over-temperature protection transistor M32 is grounded. The over-temperature protection current flows into the grounded terminal through the reference resistor Rref. The comparator Comp1 is used to compare the actual potential of the reference resistor Rref (i.e., I). otp The magnitudes of ×Rref and the over-temperature reference potential Vref, according to configuration requirements, when the over-temperature protection current I... otp When the current is equal to the preset current Iref, the actual potential of the reference resistor Rref is the over-temperature reference potential Vref, and the implicit variable relationship is Vref = Iref × Rref. For example... Figure 4 As shown, the first terminal of the action switch M_t is connected to the first preset power supply VDD through a pull-up resistor Rm, and the second terminal of the action switch M_t is grounded. The output of comparator comp1 outputs the level Thermal flag to the control terminal of the action switch M_t. The level FAULT at the first terminal of the action switch M_t is controlled by the control terminal of the action switch M_t. Figure 3 As shown, the over-temperature protection current I increases with increasing temperature. otp The over-temperature protection current I decreases, assuming the temperature is T1. otp The current is equal to the preset current Iref. When the temperature rises above T1, the over-temperature protection current I... otp When the current drops below the preset current Iref, the actual potential of the reference resistor Rref drops below the over-temperature reference potential Vref. The output level Thermal flag of comparator comp1 changes from 0 to 1, the action switch M_t turns on, and the level FAULT at the first terminal of action switch M_t is pulled down to ground, changing from 1 to 0. The output FAULT = 0 serves as the over-temperature protection flag signal. The over-temperature protection flag signal is used to indicate that the current LED temperature has reached T1, controlling the current I... cThe temperature will decrease as the temperature rises. Among them, the temperature T1 is greater than the inflection point T0. Usually, T1 is closer to T0. For example, the temperature difference between T1 and T0 is a preset temperature difference. The preset temperature difference can be set according to the changes in the current-temperature curve, the actual situation of the application scenario, and user needs.

[0038] like Figure 4 As shown, in some embodiments, the second current source module 12 includes a second preset power supply Vr that provides a zero temperature coefficient voltage V0, a ​​second operational amplifier op2, a feedback switch M_f, and a feedback resistor Rf. The second preset power supply Vr is connected to the non-inverting input terminal of the second operational amplifier op2, the control terminal of the feedback switch M_f is connected to the output terminal of the second operational amplifier op2, the first terminal of the feedback switch M_f is connected to the inverting input terminal of the second operational amplifier op2 and grounded through the feedback resistor Rf, and the second terminal of the feedback switch M_f outputs a second current I2. The second operational amplifier op2, the feedback switch M_f, and the feedback resistor Rf form a negative feedback loop, generating a second current I2 = V0 / Rf.

[0039] Figure 5 It shows Figure 2 and Figure 4 The circuit structure diagram shown is an example implementation of the first current source unit. Figure 5 As shown, in some embodiments, the first current source unit includes a first MOSFET M1, a second MOSFET M2, a third MOSFET M3, a first operational amplifier op1, a first transistor Q1, a second transistor Q2, and a first resistor R1 with zero temperature coefficient, wherein: the first terminal of the first MOSFET M1, the first terminal of the second MOSFET M2, and the first terminal of the third MOSFET M3 are connected to a first preset power supply VDD; the control terminals of the first MOSFET M1, the second MOSFET M2, and the third MOSFET M3 are connected to the output terminal of the first operational amplifier op1; The second terminal of MOSFET M1, the first terminal of MOSFET Q1, and the control terminal of MOSFET Q1 are connected to the inverting input of the first operational amplifier op1. The second terminal of MOSFET M2 is connected to the non-inverting input of the first operational amplifier op1 and the first terminal of the first resistor R1. The second terminal of the first resistor R1 is connected to the first terminal of MOSFET Q2 and the control terminal. The second terminals of MOSFET Q1 and MOSFET Q2 are grounded. The thermoelectric potential of MOSFET Q2 is positively correlated with the temperature of the LED. The second terminal of MOSFET M3 is used to output a real-time temperature current I based on the thermoelectric potential. ptat .

[0040] like Figure 5 As shown, the first operational amplifier op1 maintains the voltages across Vn and Vp equal through its operational amplifier characteristics and feedback loop. At this time, the real-time temperature current I output from the second terminal of the third MOSFET M3 is... ptatThe calculation process is as follows:

[0041] I ptat =K p ×Vt×ln(n) / r1;

[0042] Among them, K p Let be the mirror image ratio of the second MOSFET M2 and the third MOSFET M3, n be the ratio of the second transistor Q2 to the first transistor Q1, r1 be the resistance value of the first resistor R1, and Vt be the thermoelectric potential of the second diode Q2, which is directly proportional to the temperature of the second diode Q2, specifically: Vt = K × T / q, where K is the Boltzmann constant, q is the electron charge of the second diode Q2, and T is the temperature of the second diode Q2. This embodiment requires real-time temperature current I. ptat The first current source unit is positioned close to the LED, and the heat generated by the LED affects the temperature of the second diode Q2. This causes the thermoelectric potential of the second transistor Q2 to be positively correlated with the LED temperature, thus resulting in the real-time temperature-current I output by the first current source unit. ptat It can reflect the temperature of the LED.

[0043] like Figures 2 to 5 As shown, the control transistor and the controlled transistor are the same type of switching transistor. The control transistor, controlled transistor, over-temperature protection transistor, action switch transistor, and feedback switch transistor can be selected according to their positions. For example, the first control transistor, first controlled transistor, action switch transistor, and feedback switch transistor can be implemented using NMOS transistors, while the second control transistor, second controlled transistor, third control transistor, third controlled transistor, over-temperature protection transistor, first MOS transistor, second MOS transistor, and third MOS transistor can be implemented using PMOS transistors. The specific component types and sizes can be set according to the parameter requirements of the actual circuit and are not limited here.

[0044] According to an embodiment of the control circuit for LED power supply, since the first current I1 is positively correlated with the temperature of the LED, the control current I output based on the first current I1 is... c The current I is negatively correlated with the temperature of the LED, and the control current I increases as the temperature rises. c The operating current I for powering the LED decreases. wThe decrease in current reduces the heat output of the LED, allowing it to operate in a controllable thermal steady state and achieving more reliable and stable temperature protection. Depending on the specific implementation, the first current source module includes multiple first current source units or multiple second current source units, as well as a first switch. The first switch controls the inflection point of the current curve. The first current mirror unit includes multiple first controlled transistors and second switches. The second switch controls the downward slope of the current curve. The number of first current source units, second current source units, first switches, first controlled transistors, and second switches are not required to be the same or identical; they can be set according to the actual situation.

[0045] The control circuit of this embodiment may further include a processor configured to set the inflection point or the downward slope of the current curve by controlling the state of the first switch or the second switch, and to receive an over-temperature protection flag signal.

[0046] Figure 6 A circuit structure diagram of an LED power supply device according to an embodiment of the present invention is shown, such as... Figure 6 As shown, the LED power supply device 600 includes: the control circuit 601 for LED power supply described above; and a current output module 602, connected to the control circuit 601, configured to receive the control current output by the control circuit 601 and output a corresponding operating current to power the LED based on the control current.

[0047] like Figure 6 As shown, in some embodiments, the current output module 602 includes a first output resistor Ro1, a second output resistor Ro2, a third operational amplifier op3, and an output switch M0. The first terminal of the first output resistor Ro1 is connected to the control circuit 601 and to the non-inverting input of the third operational amplifier op3. The control terminal of the output switch M0 is connected to the output of the third operational amplifier op3. The first terminals of the output switch M0 and the second output resistor Ro2 are connected to the inverting input of the third operational amplifier op3. The second terminals of the first and second output resistors Ro1 and Ro2 are grounded. The second terminal of the output switch M0 is connected to an LED for outputting the operating current. The other terminal of the LED is connected to the supply voltage LEDX. The third operational amplifier op3, the second output resistor Ro2, and the output switch M0 form a negative feedback loop to maintain a constant operating current for the LED, ultimately outputting an operating current I to the LED to power it. w =K0×I C ;

[0048] Where K0 = ro1 / ro2, ro1 and ro2 are the resistance values ​​of the first output resistor Ro1 and the second output resistor Ro2, respectively. Figure 6As shown, there are one or more LEDs. When there are multiple LEDs, their connection relationship is at least one of series or parallel. The specific settings of the LEDs can be adjusted according to the actual situation, and will not be elaborated here.

[0049] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0050] This invention can be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithm described in a particular embodiment can be modified without departing from the basic spirit of the invention. Therefore, the present embodiments are to be regarded as exemplary rather than limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and scope of the claims and their equivalents are thus included within the scope of the invention.

Claims

1. A control circuit for powering LEDs, comprising: The first current source module is configured to output a first current that is positively correlated with the temperature of the LED; The second current source module is configured to output a second current that is unaffected by the temperature of the LED; The slope current mirror module is connected to the first current source module and is configured to mirror the first current according to a first preset ratio to generate a first mirror current. as well as A control current module, connected to the second current source module and the slope current mirror module, is configured to receive the second current and the first mirror current, and output a control current based on the difference between the second current and the first mirror current, wherein the operating current supplying power to the LED is based on the control current. The slope current mirror module includes: A first current mirror unit includes a first control transistor and a first controlled transistor. A first terminal of the first control transistor is connected to a control terminal of the first control transistor, a control terminal of the first controlled transistor, and a first current source module. A second terminal of the first control transistor is grounded to the second terminal of the first controlled transistor. The first terminal of the first controlled transistor serves as the output terminal of the first current mirror unit. The second current mirror unit includes a second control transistor and a second controlled transistor. The first ends of the second control transistor and the second controlled transistor are connected to a first preset power supply. The control terminal of the second control transistor is connected to its second end, the control terminal of the second controlled transistor, and the output terminal of the first current mirror unit. The second end of the second controlled transistor serves as the output terminal of the second current mirror unit for outputting the first mirrored current. Wherein, the current mirror ratio between the first control transistor and the first controlled transistor is the first unit ratio, the current mirror ratio between the second control transistor and the second controlled transistor is the second unit ratio, and the first preset ratio is the product of the first unit ratio and the second unit ratio.

2. The control circuit according to claim 1, wherein, The first current source module includes a first current source unit and a second current source unit connected sequentially between a first preset power supply and a ground point. The first current source unit is configured to output a real-time temperature current that is positively correlated with the temperature of the LED. The second current source unit is configured to output a reference temperature current that is not affected by the temperature of the LED. The node between the first current source unit and the second current source unit is used to output the difference current between the real-time temperature current and the reference temperature current as the first current.

3. The control circuit according to claim 2, wherein, The number of the first current source units is one or more, the number of the second current source units is one or more, and the first current source module further includes a first switch, which is connected to one of the first current source units and the second current source units and is configured to cut off or connect the current path of the first current source unit or the second current source unit connected thereto.

4. The control circuit according to claim 2, wherein, The first current source unit includes a first MOSFET, a second MOSFET, a third MOSFET, a first operational amplifier, a first transistor, a second transistor, and a first resistor with zero temperature coefficient, wherein: The first end of the first MOSFET, the first end of the second MOSFET, and the first end of the third MOSFET are connected to the first preset power supply. The control terminals of the first MOSFET, the second MOSFET, and the third MOSFET are connected to the output terminal of the first operational amplifier. The second terminal of the first MOSFET, the first terminal of the first transistor, and the control terminal of the first transistor are connected to the inverting input terminal of the first operational amplifier; The second terminal of the second MOSFET is connected to the non-inverting input terminal of the first operational amplifier and the first terminal of the first resistor; The second end of the first resistor is connected to the first end and the control end of the second transistor; The second terminals of the first transistor and the second transistor are grounded; The thermoelectric potential of the second transistor is positively correlated with the temperature of the LED, and the second terminal of the third MOS transistor is used to output the real-time temperature current based on the thermoelectric potential.

5. The control circuit according to claim 1, wherein, The number of the first controlled transistors is multiple, and the first current mirror unit further includes a second switch. The second switch is connected to any of the first controlled transistors and is configured to cut off or connect the current path of the first controlled transistor connected thereto. The ratio of the first unit is the current mirror ratio of the first control transistor and the first controlled transistor with the current path connected.

6. The control circuit according to claim 1, wherein, The control current module includes a third control transistor and a third controlled transistor. The first end of the third control transistor and the first end of the third controlled transistor are connected to a first preset power supply. The second end of the third control transistor is connected to the control terminal of the third control transistor, the control terminal of the third controlled transistor, the slope current mirror module, and the second current source module. The second end of the third controlled transistor serves as the output terminal of the control current module for outputting the control current.

7. The control circuit according to claim 6, wherein, The control current module also includes an over-temperature protection tube. The first end of the over-temperature protection tube is connected to the first preset power supply, the control end of the over-temperature protection tube is connected to the control end of the third control tube, and the second end of the over-temperature protection tube outputs an over-temperature protection current. The control circuit further includes an over-temperature protection flag module connected to the control current module, configured to receive the over-temperature protection current and output an over-temperature protection flag signal when the over-temperature protection current is less than a preset current.

8. The control circuit according to claim 7, wherein, The over-temperature protection flag module includes a comparator, a reference resistor, and an action switch transistor. The over-temperature protection transistor and the reference resistor are connected in series. The first input terminal of the comparator is connected to the over-temperature reference potential. The second input terminal of the comparator is connected to the node between the over-temperature protection transistor and the reference resistor. The output terminal of the comparator is connected to the control terminal of the action switch transistor to control the action switch transistor to output the over-temperature protection flag signal.

9. An LED power supply device, comprising: Control circuit for LED power supply as described in any one of claims 1 to 8; as well as A current output module, connected to the control circuit, is configured to receive the control current output by the control circuit and output a corresponding operating current to power the LED based on the control current.

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