Control circuit for LED power supply and LED power supply device

Abstract

The invention discloses a control circuit for LED power supply and an LED power supply device. The control circuit comprises a first current source module configured to output a first current positively correlated with the temperature of the LED; the second current source module is configured to output a second current which is not influenced by the temperature of the LED; the slope current mirror module is connected with the first current source module and is configured to mirror the first current according to a first preset proportion so as to generate a first mirror current; and the control current module is connected with the second current source module and the slope current mirror module, and is configured to receive the second current and the first mirror current and output a control current based on a difference current between the second current and the first mirror current, and the working current for supplying power to the LED is based on the control current. The control circuit provides more reliable and stable dynamic temperature protection for the LED.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to a control circuit for LED power supply and an LED power supply device. Background Art

[0002] With the development of electronic products such as televisions, monitors, and mobile devices, it has become a mainstream trend to apply light-emitting diodes (LEDs) to display devices of various electronic products. In order to prevent the LED from overheating and damaging the device, the traditional LED control system usually has an over-temperature protection mechanism, which directly cuts off the power supply to protect the device when the LED temperature reaches the over-temperature point. However, due to the deviation of the processing technology, different devices and different circuit compositions may cause the temperature performance of the LED to show differences. The over-temperature protection mechanism with a fixed over-temperature point is difficult to achieve a stable and reliable protection effect. The over-temperature point may be too low, causing the LED to shut down prematurely and the screen to go black, or the over-temperature point may be too high, causing the LED to fail to shut down in time and cause damage to the device. The over-temperature protection effect is not ideal, and the user experience is poor. 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 that is positively correlated with the temperature of the LED; a second current source module, configured to output a second current that is not affected by the temperature of the LED; 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 mirror 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 mirror current, and output a control current based on a difference current between the second current and the first mirror current, wherein an operating current for powering the LED is based on the control current.

[0004] According to an embodiment of the present invention, the LED power supply device includes: the above-mentioned control circuit for LED power supply; and a current output module, connected to the control circuit, configured to receive the control current output by the control circuit and output a corresponding working current to power the LED based on the control current. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0007] Figure 2 Shows Figure 1 A schematic diagram of a circuit structure of an example implementation of a control circuit for powering an LED is shown;

[0008] Figure 3 shows a current curve graph based on temperature according to an embodiment of the present invention;

[0009] Figure 4 Shows Figure 1 A circuit structure schematic diagram of another exemplary implementation of a control circuit for powering an LED is shown;

[0010] Figure 5 Shows Figure 2 and Figure 4 A schematic diagram of a circuit structure of an example implementation of the first current source unit 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 DESCRIPTION

[0012] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement and improvement of elements, parts and algorithms without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and technologies are not shown to avoid unnecessary ambiguity to the present invention.

[0013] Taking into account that different LED processing technologies make it difficult for an over-temperature protection mechanism with a fixed over-temperature point to achieve a stable and reliable protection effect during LED power supply, a control circuit and an LED power supply device for LED power supply according to an embodiment of the present invention are proposed, which can reduce the heat power of the LED and make the LED work in a controllable thermal steady state, thereby achieving more reliable and stable temperature protection and reducing the probability of LED shutdown, black screen or device damage due to overheating.

[0014] Figure 1 FIG. 2 shows a schematic diagram of the logic structure of a control circuit for powering an LED according to an embodiment of the present invention. Figure 1 As shown, the control circuit 10 for powering an 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 not affected by the temperature of the LED; 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 mirror 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 ′ , and based on the second current I2 and the first mirror current I1 ′ The difference current I3 outputs the control current I C , where the operating current I w Based on the control current I C .

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

[0016] I1 ′ =K1×I1;

[0017] I3=I2-I1 ′ ;

[0018] I3=I2-K1×I1.

[0019] Based on the control current I C Produces working current I w And the working current I w When the LED is powered, the LED generates heat during operation, and the temperature of the LED increases. Since the first current I1 is positively correlated with the temperature of the LED, as the temperature of the LED increases, the first current I1 increases, and the control current I c Reduced, making the operating current I w Reduce, so that the heat power of the LED decreases, the temperature rise rate slows down, and the LED works in a controllable thermal steady state.

[0020] Compared with the solution of directly cutting off the power supply when the temperature rises to the over-temperature point, Figure 1 The control circuit 10 shown can dynamically control the operating current I based on the temperature w , before the LED temperature rises to the over-temperature point, the control current I c To reduce the operating current I w , which reduces the heating rate of the LED and slows down the temperature rise process. The probability of the LED temperature rising to the over-temperature point is reduced, and the probability of the LED suddenly shutting down and displaying a black screen or the device being burned out when it reaches the over-temperature point is reduced. It provides more reliable and stable dynamic temperature protection for the LED, the LED's working time and life are longer, and the user experience is improved.

[0021] Figure 2 Shows Figure 1 The circuit structure diagram of an example implementation of a control circuit for powering an LED is shown in FIG. 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 which are sequentially connected between the first preset power supply VDD and the ground point, wherein: the first current source unit Iptat is configured to output a real-time temperature current I which 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 which is not affected 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, so:

[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, in the real-time temperature current I ptat Greater than the reference temperature current I tha When the real-time temperature current I ptat Not greater than the reference temperature current I tha When the first current source module 11 does not output current, the first current I1 = 0, I3 = I2-K1×I1 = I2, and the control current I c The second current I2 is determined based on the difference current I3 and is not affected by the temperature of the LED. c Not affected by the temperature of the LED. In real-time temperature current I ptat Not greater than the reference temperature current I tha When the first current I1 is zero, the real-time temperature current I ptat Greater than the reference temperature current I tha When , the first current I1 is greater than zero and increases with temperature.

[0024] Based on the above analysis, we can know that the reference temperature current I tha Can be used to set the control current I c The inflection point of the change with temperature, the real-time temperature current I is known ptat Positively correlated with temperature, assuming that the real-time temperature current I ptat (T) is the reference temperature current I when the temperature T is T0 tha , that is I ptat (T0) = I tha At this time, the curve of the difference current I3 changing with temperature is as follows Figure 3As shown, when the temperature is not greater than T0, I3 = I2. After the temperature is greater than T0, the difference current I3 gradually decreases with the increase of temperature. The temperature T0 is the inflection point of the difference current I3. c Based on the difference 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 Example of the variation curve of the difference current I3 when it is linearly positively correlated with the temperature. If the real-time temperature current I ptat The positive correlation with temperature is other nonlinear changes, and the above-mentioned change rules also exist, that is, when the temperature of the LED is not greater than the inflection point, the control current I c Remain unchanged. After the temperature of the LED is greater than the inflection point, the control current I c Decreases as temperature increases.

[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 tube M10 and a first controlled tube M11, the first end of the first control tube M10 is connected to the control end of the first control tube M10, the control end of the first controlled tube M11 and the first current source module 11, the second end of the first control tube M10 and the second end of the first controlled tube M11 are grounded, and the first end of the first controlled tube M11 serves as the output end of the first current mirror unit 131; the second current mirror unit 132 includes a second control tube M20 and a second controlled tube M21, the first end of the second control tube M20 and the first end of the second controlled tube M21 are connected to the first preset power supply VDD, the control end of the second control tube M20 is connected to the second end of the second control tube M20, the control end of the second controlled tube M21 and the output end of the first current mirror unit 131, and the second end of the second controlled tube M21 serves as the output end of the second current mirror unit 132 for outputting the first mirror current I1 ′ The current mirror ratio of the first control tube M10 and the first controlled tube M11 is a first unit ratio k1, the current mirror ratio of the second control tube M20 and the second controlled tube M21 is a second unit ratio k2, and the first preset ratio K1 is the product of the first unit ratio k1 and the second unit ratio k2 (ie, 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 ′ , so that 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 tube M30 and a third controlled tube M31, the first end of the third control tube M30 and the first end of the third controlled tube M31 are connected to the first preset power supply VDD, the second end of the third control tube M30 is connected to the control end of the third control tube M30, the control end of the third controlled tube M31, the slope current mirror module 13 and the second current source module 12, and the second end of the third controlled tube M31 serves as the output end of the control current module 14 for outputting the 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, and 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 tube M30, the slope current mirror module 13 and the second current source module 12, the current flowing through the third control tube M30 is the difference current I3 of the second current and the first mirror current = I2-I1 ′ The third controlled tube M31 is used to mirror the current flowing through the third control tube M30 to generate a control current. At this time, I C =k3×I3=k3×(I2-K1×I1), where I C To control the current, k3 is the mirror ratio between the third control tube M30 and the third controlled tube M31. Since the first current I1 is positively correlated with the temperature of the LED, when the temperature of the LED increases, the first current I1 increases, and the control current I C Reduce the operating current I w The corresponding reduction reduces the heat generation power of the LED.

[0032] Figure 4 Shows Figure 1 FIG. 1 is a schematic diagram of a circuit structure of another exemplary implementation of a control circuit for powering an LED. Figure 4 and Figure 2 The relationship between the original modules in is the same. Figure 4As shown, in some embodiments, 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, the first switch is connected to one of the first current source unit and the second current source unit and is configured to cut off or conduct the current path of the first current source unit or the second current source unit connected thereto. When the number of the first current source unit or the second current source unit is multiple, the multiple first current source units are connected in parallel, and the multiple second current source units are connected in parallel. The number of the first switches is not limited, and can be one or more, and each first switch can be connected to the first current source unit or the second current source unit, and is configured to cut off or conduct the current path connected thereto.

[0033] For example, Figure 4 As shown, the number of first current source units is one, the number of second current source units is m (respectively denoted as Itha1-Itham, where m is an integer greater than 1), the number of first switches is m (respectively 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 turn on the current path of the second current source unit connected thereto, the common node refers to the node between the first current source unit and the second current source unit, and when the first switch S11 is closed, the current path of the second current source unit Itha1 is turned on. Figure 4 In addition to the examples, the first switch configured to cut off or turn on the current path of the second current source unit may also be arranged between the second current source unit and the ground terminal; the first switch configured to cut off or turn on the current path of the first current source unit may be arranged 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 current 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 unit with the current path turned on, and the reference temperature current includes all the output currents of the second current source unit with the current path turned on. 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 thereto can be cut off or turned on, thereby adjusting the specific size relationship between the real-time temperature current and the reference temperature current, that is, adjusting Figure 3 The inflection point T0 in the change curve.

[0034] like Figure 4 As shown, in some embodiments, the number of first controlled tubes is multiple, and the multiple first controlled tubes are connected in parallel. The first current mirror unit also includes a second switch, and the second switch is connected to any first controlled tube and is configured to cut off or conduct the current path of the first controlled tube connected thereto. The first unit ratio is the current mirror ratio of the first control tube and the first controlled tube whose current path is conducted.

[0035] For example, Figure 4 As shown, the number of first controlled transistors is n (denoted as M11-M1n, n is an integer greater than 1), the number of second switches is also n (denoted as S21-S2n respectively), and each second switch is connected to a first controlled transistor and is configured to cut off or conduct the current path of the first controlled transistor connected thereto. In some examples, the second switch may be connected between the first end of the first controlled transistor and the second end of the second controlled transistor, or between the second end of the first controlled transistor and the ground terminal. In the first current mirror unit 131, each first controlled transistor with a conducting current path can mirror the current of the first control transistor to generate a corresponding mirror current, and the intermediate current I output by the first current mirror unit 131 is 10 By setting the state of the second switch to be closed or open, the current path of the first controlled tube connected thereto can be cut off or turned on, 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 Figure 3 The decreasing slope of .

[0036] like Figure 4 As shown, in some embodiments, the control current module 14 may further include an over-temperature protection tube M32, wherein a first end of the over-temperature protection tube M32 is connected to a first preset power supply VDD, a control end of the over-temperature protection tube M32 is connected to a control end of a third control tube M30, and a second end of the over-temperature protection tube M32 outputs an over-temperature protection current I otp Here, the over-temperature protection tube M32 and the third control tube M30 form a pair of current mirrors, and the over-temperature protection tube M32 mirrors the current I3 to generate an 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 the over-temperature protection current I otp And 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 tube M_t, wherein: the over-temperature protection tube M32 and the reference resistor Rref are connected in series, the first input end of the comparator comp1 is connected to the over-temperature reference potential Vref, the second input end of the comparator comp1 is connected to the node between the over-temperature protection tube M32 and the reference resistor Rref, and the output end of the comparator comp1 is connected to the control end of the action switch tube M_t, which is used to control the action switch tube M_t to output the over-temperature protection flag signal. The two input ends of the comparator comp1 are respectively the in-phase input end and the inverting input end, one of which is used as the first input end, and the other is used as the second input end. Figure 4 In the example shown, the first input terminal is a positive input terminal, the second input terminal is a negative input terminal, the other end of the reference resistor Rref that is not connected to the over-temperature protection tube M32 is grounded, and the over-temperature protection current flows into the ground 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 ×Rref) and the size of the over-temperature reference potential Vref. According to the 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. Figure 4 As shown, the first end of the action switch tube M_t is connected to the first preset power supply VDD through the pull-up resistor Rm, the second end of the action switch tube M_t is grounded, the output end of the comparator comp1 outputs the level Thermal flag to the control end of the action switch tube M_t, and the level FAULT of the first end of the action switch tube M_t is controlled by the control end of the action switch tube M_t. Figure 3 As shown, as the temperature rises, the over-temperature protection current I otp Assuming the temperature is T1, the corresponding over-temperature protection current I otp Equal to the preset current Iref, when the temperature rises to exceed T1, the over-temperature protection current I otp The over-temperature protection flag signal is used to indicate that the current LED temperature has reached T1, and the control current I cIt will decrease as the temperature increases. Among them, the temperature T1 is greater than the inflection point T0, and usually T1 is close to T0. For example, the temperature difference between T1 and T0 is a preset temperature difference, which can be set according to the curve change of current and temperature, 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 providing a zero temperature coefficient voltage V0, a ​​second op amp op2, a feedback switch tube M_f and a feedback resistor Rf, wherein the second preset power supply Vr is connected to the non-inverting input terminal of the second op amp op2, the control terminal of the feedback switch tube M_f is connected to the output terminal of the second op amp op2, the first terminal of the feedback switch tube M_f is connected to the inverting input terminal of the second op amp op2 and is grounded through the feedback resistor Rf, the second terminal of the feedback switch tube M_f outputs the second current I2, the second op amp op2, the feedback switch tube M_f and the feedback resistor Rf form a negative feedback loop to generate a second current I2=V0 / Rf.

[0039] Figure 5 Shows Figure 2 and Figure 4 FIG. 1 is a schematic diagram of a circuit structure of an exemplary implementation of the first current source unit shown in FIG. Figure 5 As shown, in some embodiments, the first current source unit includes a first MOS tube M1, a second MOS tube M2, a third MOS tube M3, a first operational amplifier op1, a first triode Q1, a second triode Q2, and a first resistor R1 with a zero temperature coefficient, and wherein: a first end of the first MOS tube M1, a first end of the second MOS tube M2, and a first end of the third MOS tube M3 are connected to a first preset power supply VDD; a control end of the first MOS tube M1, a control end of the second MOS tube M2, and a control end of the third MOS tube M3 are connected to an output end of the first operational amplifier op1; The second end of the first MOS tube M1, the first end of the first triode Q1 and the control end of the first triode Q1 are connected to the inverting input end of the first op amp op1; the second end of the second MOS tube M2 is connected to the non-inverting input end of the first op amp op1 and the first end of the first resistor R1; the second end of the first resistor R1 is connected to the first end and the control end of the second triode Q2; the second end of the first triode Q1 and the second end of the second triode Q2 are grounded; the thermoelectric potential of the second triode Q2 is positively correlated with the temperature of the LED, and the second end of the third MOS tube 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 at both ends of Vn and Vp equal through its own operational amplifier characteristics and feedback loop. At this time, the real-time temperature current I output by the second end of the third MOS tube M3 ptatThe calculation process is as follows:

[0041] I ptat =K p ×Vt×ln(n) / r1;

[0042] Among them, K p is the mirror ratio of the second MOS tube M2 and the third MOS tube M3, n is the ratio of the second triode Q2 to the first triode Q1, r1 is the resistance value of the first resistor R1, Vt is the thermoelectric potential of the second diode Q2, which is proportional to the temperature of the second diode Q2, specifically: Vt = K × T / q, where K is the Boltzmann constant, q is the electronic charge of the second diode Q2, and T is the temperature of the second diode Q2. This embodiment requires the real-time temperature current I ptat The first current source unit is located close to the LED. The heat generated by the LED affects the temperature of the second diode Q2, so that the thermoelectric potential of the second transistor Q2 is positively correlated with the temperature of the LED. This makes the real-time temperature current I output by the first current source unit ptat Can reflect the temperature of LED.

[0043] like Figures 2 to 5 As shown, the control tube and the controlled tube are the same type of switch tubes, and the control tube, the controlled tube, the over-temperature protection tube, the action switch tube, and the feedback switch tube can select the corresponding type of components according to the component position. For example, the first control tube, the first controlled tube, the action switch tube, and the feedback switch tube can be implemented by selecting NMOS tubes, and the second control tube, the second controlled tube, the third control tube, the third controlled tube, the over-temperature protection tube, the first MOS tube, the second MOS tube, and the third MOS tube can be implemented by selecting PMOS tubes. The selection of specific component types and component sizes can be set according to the various parameter requirements in the actual circuit, and is not limited here.

[0044] According to the control circuit for LED power supply of the embodiment of the present invention, since the first current I1 is positively correlated with the temperature of the LED, the control current I1 output based on the first current I1 is c Negatively correlated with the temperature of the LED, the current I is controlled when the temperature rises c The working current I wThe LED is controlled to work in a controllable thermal steady state, thereby achieving more reliable and stable temperature protection. Based on the specific implementation method, the first current source module is provided with a plurality of first current source units or a plurality of second current source units and a first switch, the first switch is used to control the inflection point of the current curve, the first current mirror unit is provided with a plurality of first controlled transistors and a second switch, the second switch is used to control the descending slope of the current curve, and the number of the first current source unit, the second current source unit, the first switch, the first controlled transistor, and the second switch is not required to be consistent or the same, and can be set according to actual conditions.

[0045] The control circuit of this embodiment may further include a processor configured to set a change inflection point or a falling 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 FIG. 4 shows a schematic diagram of a circuit structure of an LED power supply device according to an embodiment of the present invention. Figure 6 As shown, the LED power supply device 600 includes: the above-mentioned control circuit 601 for LED power supply; and a current output module 602, which is connected to the control circuit 601 and is configured to receive the control current output by the control circuit 601 and output a corresponding working 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 op amp op3, and an output switch tube M0, wherein: the first end of the first output resistor Ro1 is connected to the control circuit 601 and connected to the non-inverting input end of the third op amp op3, the control end of the output switch tube M0 is connected to the output end of the third op amp op3, the first end of the output switch tube M0 and the first end of the second output resistor Ro2 are connected to the inverting input end of the third op amp op3, the second end of the first output resistor Ro1 and the second end of the second output resistor Ro2 are grounded, and the second end of the output switch tube M0 is connected to an LED for outputting a working current. The other end of the LED is connected to a power supply voltage LEDX, and the third op amp op3, the second output resistor Ro2, and the output switch tube M0 form a negative feedback loop to maintain a constant working current of the LED, and finally output to the LED a working current I 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, the number of LEDs is one or more. When there are multiple LEDs, their connection relationship is at least one of series connection or parallel connection. The specific setting details of the LEDs can be adjusted according to actual conditions and will not be repeated here.

[0049] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present disclosure. In this regard, each box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0050] The present invention can be implemented in other specific forms without departing from its spirit and essential features. For example, the algorithms described in the specific embodiments can be modified, and the system architecture does not depart from the basic spirit of the present invention. Therefore, the current embodiments are regarded as exemplary and non-restrictive in all aspects, and the scope of the present invention is defined by the appended claims rather than the above description, and all changes falling within the meaning and equivalent scope of the claims are thus included in the scope of the present invention.

Claims

1. A control circuit for LED power supply, comprising: A first current source module is configured to output a first current that is positively correlated with the temperature of the LED; A second current source module, configured to output a second current that is not affected 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; as well as A control current module is connected to the second current source module and the slope current mirror module, and is configured to receive the second current and the first mirror current, and output a control current based on a difference current between the second current and the first mirror current, wherein an operating current for powering the LED is based on the control current.

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 which are sequentially connected between a first preset power supply and a ground point, the first current source unit is configured to output a real-time temperature current which is positively correlated with the temperature of the LED, the second current source unit is configured to output a reference temperature current which is not affected by the temperature of the LED, and the node between the first current source unit and the second current source unit is used to output a 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 also includes a first switch, which is connected to one of the first current source unit and the second current source unit and is configured to cut off or turn on 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 MOS transistor, a second MOS transistor, a third MOS transistor, a first operational amplifier, a first triode, a second triode and a first resistor with a zero temperature coefficient, and wherein: The first end of the first MOS tube, the first end of the second MOS tube and the first end of the third MOS tube are connected to the first preset power supply; The control end of the first MOS tube, the control end of the second MOS tube and the control end of the third MOS tube are connected to the output end of the first operational amplifier; The second end of the first MOS transistor, the first end of the first transistor and the control end of the first transistor are connected to the inverting input end of the first operational amplifier; The second end of the second MOS tube is connected to the non-inverting input end of the first operational amplifier and the first end 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 end of the first triode and the second end of the second triode are grounded; The thermoelectric potential of the second transistor is positively correlated with the temperature of the LED, and the second end 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 slope current mirror module comprises: A first current mirror unit comprises a first control tube and a first controlled tube, wherein a first end of the first control tube is connected to a control end of the first control tube, a control end of the first controlled tube and the first current source module, a second end of the first control tube and a second end of the first controlled tube are grounded, and the first end of the first controlled tube serves as an output end of the first current mirror unit; and a second current mirror unit, comprising a second control tube and a second controlled tube, wherein a first end of the second control tube and a first end of the second controlled tube are connected to a first preset power supply, a control end of the second control tube is connected to a second end of the second control tube, a control end of the second controlled tube and an output end of the first current mirror unit, and the second end of the second controlled tube is used as an output end of the second current mirror unit to output the first mirror current, Among them, the current mirror ratio of the first control tube and the first controlled tube is a first unit ratio, the current mirror ratio of the second control tube and the second controlled tube is a second unit ratio, and the first preset ratio is the product of the first unit ratio and the second unit ratio.

6. The control circuit according to claim 5, wherein: The number of the first controlled tubes is multiple, and the first current mirror unit also includes a second switch, which is connected to any of the first controlled tubes and is configured to cut off or conduct the current path of the first controlled tube connected thereto, and the first unit ratio is the current mirror ratio of the first control tube and the first controlled tube whose current path is conducted.

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

8. The control circuit according to claim 7, wherein: The control current module also includes an over-temperature protection tube, a first end of the over-temperature protection tube is connected to the first preset power supply, a control end of the over-temperature protection tube is connected to the control end of the third control tube, and a 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.

9. The control circuit according to claim 8, wherein: The over-temperature protection mark module includes a comparator, a reference resistor and an action switch tube. The over-temperature protection tube and the reference resistor are connected in series. The first input end of the comparator is connected to the over-temperature reference potential. The second input end of the comparator is connected to the node between the over-temperature protection tube and the reference resistor. The output end of the comparator is connected to the control end of the action switch tube, which is used to control the action switch tube to output the over-temperature protection mark signal.

10. An LED power supply device, comprising: A control circuit for powering an LED as claimed in any one of claims 1 to 9; as well as The current output module is connected to the control circuit and is configured to receive the control current output by the control circuit and output a corresponding working current based on the control current to power the LED.

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