Control circuit and lighting device

Abstract

The present invention discloses a control circuit and a lighting device, belonging to the field of lighting technology. Compared with the prior art, during the power-on process of the control circuit, the voltage input to the driving input terminal of the constant current driving module rises slowly, resulting in the problem of current overshoot in the light source load. In the control circuit disclosed in the present invention, since the output current of the first regulating output terminal is positively correlated with the output voltage of the voltage limiting terminal, and the output current of the second regulating output terminal is negatively correlated with the output voltage of the voltage limiting terminal, therefore, during the power-on process of the control circuit, that is, during the process when the voltage of the voltage limiting terminal changes from 0 to the first threshold value, the current input to the driving input terminal can be relatively constant, so that the working current on the light source load connected to the constant current driving module is also relatively constant, avoiding the phenomenon of current overshoot on the light source load.

Description

Technical Field

[0001] The present application relates to the field of lighting technology, and in particular to a control circuit and a lighting device. Background Art

[0002] In lighting devices, the control circuit can use constant power regulation technology to drive the load, that is, when the line network input voltage is high, the output current is reduced to keep the input power of the light source load basically unchanged.

[0003] However, with the current constant power regulation technology, the current output to the light source load has an overshoot phenomenon at the moment of power-on, which makes the light source load easily damaged or broken down. Summary of the invention

[0004] In order to solve the problem of current overshoot on the light source load of the control circuit at the moment of power-on, the present application provides a control circuit and a lighting device.

[0005] The control circuit provided by the present invention comprises: a signal sampling module, a constant power regulation module, a negative feedback regulation module and a constant current driving module;

[0006] The signal sampling module includes a voltage limiting terminal, the voltage limiting terminal is used to output a voltage limiting value, and the voltage limiting value is lower than a first threshold;

[0007] The constant power regulation module comprises a first regulation input terminal and a first regulation output terminal, the voltage limiting terminal is connected to the first regulation input terminal, and the output current of the first regulation output terminal is positively correlated with the input voltage of the first regulation input terminal;

[0008] The negative feedback regulation module comprises a second regulation input terminal and a second regulation output terminal, the voltage limiting terminal is connected to the second regulation input terminal, and the output current of the second regulation output terminal is negatively correlated with the input voltage of the second regulation input terminal;

[0009] The constant current driving module comprises a driving input terminal, and the first regulating output terminal and the second regulating output terminal are connected to the driving input terminal.

[0010] In the above-mentioned control circuit, the signal sampling module includes a first resistor and a first capacitor, the two ends of the first resistor are respectively connected to the signal sampling input voltage and the first capacitor, the two ends of the first capacitor are respectively connected to the first resistor and the ground end, the voltage limiting end is an endpoint located between the first resistor and the first capacitor, and the first threshold is determined by the capacitance of the first capacitor.

[0011] In the above-mentioned control circuit, the constant power regulation module includes a second resistor and a constant power current mirror, the second resistor is connected between the voltage limiting end and the constant power current mirror, and the constant power current mirror is connected between the second resistor and the constant current driving module.

[0012] In the above-mentioned control circuit, the constant current driving module includes a first operational amplifier, a third resistor, a first switching tube and a current regulating resistor; the first operational amplifier includes a first positive input terminal, a first negative input terminal and a first amplified output terminal, the first switching tube includes a first source, a first drain and a first gate, the first positive input terminal inputs a first reference voltage, the first source and the first gate are short-circuited and connected to the first amplified output terminal, the third resistor is connected between the first amplified output terminal and the first negative input terminal, the current regulating resistor is connected between the first source and the ground terminal, the driving input terminal includes the first negative input terminal, and the first drain is used to connect the light source load.

[0013] In the above-mentioned control circuit, the negative feedback regulation module includes a fourth resistor, a second operational amplifier, a second switch tube and a feedback current mirror; the second operational amplifier includes a second positive input terminal, a second negative input terminal and a second amplification output terminal, and the second switch tube includes a second source, a second drain and a second gate; the feedback current mirror includes a feedback input terminal and a feedback output terminal; the second positive input terminal inputs a second reference voltage, the second source and the second gate are short-circuited and connected to the second amplification output terminal and the second negative input terminal, and the fourth resistor is connected between the second gate and the voltage limiting terminal; the second drain is connected to the feedback input terminal, and the second regulation output terminal includes the feedback output terminal.

[0014] In the above control circuit, the second reference voltage is equal to the first threshold value.

[0015] In the above control circuit, the number of the constant current driving module is one;

[0016] Or the number of the constant current driving modules is at least two, at least two of the constant current driving modules are arranged in parallel, and at least two of the second drains are used to be connected in parallel to the light source load.

[0017] The above-mentioned control circuit further includes a power supply module, which provides power for the signal sampling module, the constant power regulation module, the negative feedback regulation module and the constant current driving module.

[0018] In the above-mentioned control circuit, the signal sampling module, the constant power regulation module, the negative feedback regulation module and the constant current driving module are centrally arranged in an integrated circuit; or the constant power regulation module and the negative feedback regulation module are centrally arranged in an integrated circuit.

[0019] In the above control circuit, when the output voltage of the voltage limiting end is between zero and the first threshold value, the sum of the output current of the first regulating output end and the output current of the second regulating output end is a constant value.

[0020] The present invention provides a lighting device, comprising a light source load and a control circuit as described in any one of the above items, wherein the light source load is an LED light source.

[0021] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0022] Compared with the prior art, during the power-on process of the control circuit, the voltage input to the driving input terminal of the constant current driving module rises slowly, resulting in the problem of current overshoot in the light source load. In the control circuit of the embodiment of the present invention, since the output current of the first regulating output terminal is positively correlated with the output voltage of the voltage limiting terminal, and the output current of the second regulating output terminal is negatively correlated with the output voltage of the voltage limiting terminal, therefore, during the power-on process of the control circuit, that is, during the process when the voltage of the voltage limiting terminal increases from 0 to the first threshold value, the current input to the driving input terminal can be relatively constant, so that the working current on the light source load connected to the constant current driving module is also relatively constant, avoiding the phenomenon of current overshoot on the light source load. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 A module schematic diagram of a control circuit in the prior art is shown;

[0025] Figure 2 Shows Figure 1 Schematic diagram of the devices included in each module;

[0026] Figure 3a The waveform diagram of Vt' during the working process is shown;

[0027] Figure 3b The waveform diagram of Iout' during the working process is shown;

[0028] Figure 3c shows a schematic diagram of the waveform of Vt' at the moment of power-on;

[0029] Figure 3d The waveform diagram of IA1' at the moment of power-on is shown;

[0030] Figure 3e Schematic diagram of the waveform of Iout' at the moment of power-on;

[0031] Figure 4 A module schematic diagram of a control circuit is provided for Embodiment 1 of the present invention;

[0032] Figure 5 Shows Figure 4 Schematic diagram of the devices included in each module;

[0033] Figure 6a Shows Figure 5 The waveform diagram of Vt at the moment of power-on;

[0034] Figure 6b Shows Figure 5 The waveform diagram of IA1 at the moment of power-on;

[0035] Figure 6c Shows Figure 5 The waveform diagram of IA2 at the moment of power-on;

[0036] Figure 6d Shows Figure 5 The waveform diagram of IA3 at the moment of power-on;

[0037] Figure 6e Shows Figure 5 The waveform diagram of Iout at the moment of power-on;

[0038] Figure 7 Shows the Figure 5 The schematic diagram of the application circuit after the integration of other modules except the light source load.

[0039] Figure 8 A schematic diagram showing a device in which the control circuit of Embodiment 2 of the present invention includes two constant current drive modules connected in parallel;

[0040] Description of reference numerals:

[0041] 100'-control circuit in the prior art; 10'-signal sampling module; 20'-constant power adjustment module; 30'-constant current drive module; 40'-power supply module; 50'-light source load;

[0042] Vin'-signal sampling input voltage; R1'-first resistor; R2'-second resistor; R3'-third resistor; C1'-first capacitor; M1'-first switch tube; Rext'-current regulating resistor; VT'-voltage limiting terminal; Vt'-voltage limiting voltage value; Vth'-drain voltage; INV1'-first operational amplifier; W'-current mirror module; IA1'-first regulated output current; Vref1'-first reference voltage; Iout'-load working current;

[0043] 100-control circuit; 10-signal sampling module; 20-constant power regulation module; 21-first regulation input terminal; 22-first regulation output terminal; 30-negative feedback regulation module; 31-second regulation input terminal; 32-second regulation output terminal; 40-constant current drive module; 41-drive input terminal; 50-power supply module; 60-light source load;

[0044] Vin-signal sampling input voltage; R1-first resistor; R2-second resistor; R3-third resistor; R4-fourth resistor; C1-first capacitor; M1-first switch tube; M2-second switch tube; M3-third switch tube, M1-1-fourth switch tube; Rext-current regulating resistor; VT-voltage limiting end; Vt-voltage limiting voltage value; Vth-drain voltage; INV1-first op amp; INV2-second op amp; INV1-1-third op amp; W1-constant power current mirror; W2-feedback current mirror; IA1-first regulated output current; IA2-second regulated output current; IA3-drive input current; Vref1-first reference voltage; Vref2-second reference voltage; Iout-load working current; Iout1-first load current; Iout2-second load current; U1-chip. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present application clearer, the technical solution of the present application will be clearly and completely described below in combination with the specific embodiments of the present application and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0046] Before introducing the embodiments of the present invention, Figure 1 , Figure 2 and Figure 3a-3e , specifically describing the phenomenon of current overshoot on the light source load 50 ′ in the current control circuit 100 ′.

[0047] like Figure 1 The figure shows a module diagram of a conventional control circuit 100' based on constant power technology. The control circuit 100' comprises a signal sampling module 10', a constant power regulation module 20', a constant current driving module 30' and a power supply module 40'. The control circuit 100' provides operating current for a light source load 50'. Figure 2 yes Figure 1 A specific schematic diagram of the control circuit 100' is shown in FIG. Figure 2The signal sampling input voltage Vin' input to the signal sampling module 10' can be obtained from the input end of the power supply module 40' or the constant current input module. In addition, the power supply module 40' can also supply power to the signal sampling module 10', the constant power adjustment module 20', the constant current driving module 30' and the light source load 50' at the same time. Figure 2 In the figure, the first resistor R1', the second resistor R2', and the first switch tube M1' form a working loop. The working current of this loop generates a first regulated output current IA1' after passing through the current mirror module W' in the constant power regulation module 20'. After the first switch tube M1' is turned on, the drain voltage Vth' on the drain of the first switch tube M1' is Vth'. The current mirror module W' includes a first current mirror and a second current mirror. The current ratio of the first current mirror is K1, and the current ratio of the second current mirror is K2. The following formula can be obtained.

[0048]

[0049] Further, in Figure 2 In the embodiment, the first positive input terminal of the first operational amplifier INV1' inputs a first reference voltage Vref1', and the current regulating resistor Rext' can regulate the current through the light source load 50', including the load operating current Iout' of the LED light string, which is obtained by the following formula.

[0050]

[0051] In formula (1), only the signal sampling input voltage Vin' is a variable. Figure 1 As shown, when the input voltage of the power supply module 40' increases, the signal sampling input voltage Vin' increases, the first regulated output current IA1' increases, and the load operating current Iout' on the light string in formula (2) decreases; when the input voltage of the power supply module 40' decreases, the signal sampling input voltage Vin' decreases, the first regulated output current IA1' decreases, and the load operating current Iout' on the light string increases. Figure 3a and Figure 3b As shown in the waveform diagram, when the signal sampling input voltage Vin' is a fixed value, the voltage limit voltage Vt' is also a fixed value, and the corresponding load working current Iout' is a fixed value. Figure 3a and Figure 3b It can be seen that during the working process, the changing trends of the voltage limit value Vt' and the load working current Iout' are opposite, or in other words, the two are negatively correlated. Figure 2The first capacitor C1' shown converts the voltage signal of the voltage limiting terminal VT' into a DC voltage. When the control circuit 100 is powered on, the signal sampling input voltage Vin' passes through the first resistor R1' and charges the first capacitor C1' at the same time. During the charging process of the first capacitor C1', after a period of time t, the voltage value of the voltage limiting terminal VT', that is, the voltage limiting voltage value Vt', rises from 0V to a fixed value, such as Figure 3c As shown. During this time t, the current passing through the voltage limiting terminal VT' changes from 0 to a fixed value, and is equal to the ratio of (Vin'-Vth') to (R1'+R2'). The first regulated output current IA1' generated after passing through the first current mirror and the second current mirror in the current mirror module W' has a current waveform that rises from 0 to a fixed value when the control circuit 100 is powered on, as shown Figure 3d When IA1 is at the minimum value of 0V, it can be seen from formula (2) that the load operating current Iout' is at the maximum value, as shown in Figure 3e After the control circuit 100 is powered on and the first capacitor C1' is fully charged, a fixed voltage is maintained at the voltage limiting terminal VT'. At this time, when the first regulated output current IA1' is at the maximum value, the load operating current Iout' is reduced to the minimum value and outputs this fixed current value. The load operating current Iout' on the light source load 50' at the moment the control circuit 100 is powered on is shown in FIG. Figure 3e As shown in Figure 1, a current overshoot waveform is generated at the moment of power-on.

[0052] Example 1

[0053] In order to solve the problem of current overshoot on the light source load including the LED light string during the power-on process, an embodiment of the present invention provides a control circuit 100, which provides a working current for the light source load 60 such as the LED light string without the problem of current overshoot during the power-on process.

[0054] like Figure 4 As shown, the control circuit 100 of the embodiment of the present invention includes: a signal sampling module 10 , a constant power regulation module 20 , a negative feedback regulation module 30 and a constant current driving module 40 .

[0055] Among them, Figure 5The signal sampling module 10 includes a voltage limiting terminal VT, and the voltage limiting terminal VT is used to output a voltage limiting voltage value Vt lower than the first threshold. The constant power regulation module 20 includes a first regulation input terminal 21 and a first regulation output terminal 22, and the voltage limiting terminal VT is connected to the first regulation input terminal 21, and the output current of the first regulation output terminal 22 is positively correlated with the input voltage of the first regulation input terminal 21. The negative feedback regulation module 30 includes a second regulation input terminal 31 and a second regulation output terminal 32, and the voltage limiting terminal VT is connected to the second regulation input terminal 31, and the output current of the second regulation output terminal 32 is negatively correlated with the input voltage of the second regulation input terminal 31. The constant current driving module 40 includes a driving input terminal 41, and the first regulating output terminal 22 and the second regulating output terminal 32 are connected to the driving input terminal 41. Since the output current of the first regulating output terminal 22 is positively correlated with the voltage limiting voltage value Vt of the voltage limiting terminal VT, and the output current of the second regulating output terminal 32 is negatively correlated with the voltage limiting voltage value Vt of the voltage limiting terminal VT, therefore, during the power-on process of the control circuit 100, that is, the process in which the voltage of the voltage limiting terminal VT changes from 0 to the first threshold value, the current input to the driving input terminal 41 can be relatively constant, so that the load working current Iout on the light source load 60 connected to the constant current driving module 40 is also relatively constant, avoiding the phenomenon of current overshoot on the light source load 60.

[0056] In the embodiment of the present invention, the signal sampling module 10 may include a first capacitor C1 and a first resistor R1, and the first resistor R1 and the first capacitor C1 are sequentially connected in series between the signal sampling input voltage Vin and the ground terminal. In other words, the two ends of the first resistor R1 are respectively connected to the signal sampling input voltage Vin and the first capacitor C1, and the two ends of the first capacitor C1 are respectively connected to the first resistor R1 and the ground terminal, and the voltage limiting terminal VT is located at the endpoint between the first capacitor C1 and the first resistor R1. Since the two ends of the first capacitor C1 are the voltage limiting terminal VT and the ground terminal, respectively, at the initial moment when the power supply supplies power to the signal sampling module 10, the voltage value of the two ends of the first capacitor C1 is 0V, and the voltage limiting voltage value Vt on the voltage limiting terminal VT is also 0V, until the first capacitor C1 is fully charged, the voltage limiting voltage value Vt on the voltage limiting terminal VT is also fixed to, in other words, the maximum value of the voltage that can be output on the voltage limiting terminal VT can be determined by the capacitance of the first capacitor C1, that is, the first threshold value is determined by the capacitance of the first capacitor C1. Of course, as a variation, other components may be used to determine the first threshold value on the voltage limiting end, so that the voltage of the voltage limiting end VT rises from 0V to the first threshold value during the power-on process, which will not be described in detail here.

[0057] In an embodiment of the present invention, the constant power regulation module 20 may include a second resistor R2 and a constant power current mirror W1. The second resistor R2 is connected between the voltage limiting terminal VT and the constant power current mirror W1, and the constant power current mirror W1 is connected between the second resistor R2 and the constant current driving module 40. The constant power current mirror W1 includes at least one current mirror module, specifically, it may include a first current mirror and a second current mirror connected in series, and of course, more current mirrors may be connected in series. The current ratio of the first current mirror is K1, and the current ratio of the second current mirror is K2.

[0058] Referring to the above formula (1), the current output by the first regulating output terminal 22 of the constant power regulating module 20 is the first regulating output current IA1, which can be determined as follows:

[0059]

[0060] It can be seen from formula (3) that the magnitude of the first regulated output current IA1 is positively correlated with the signal sampling input voltage Vin, that is, positively correlated with the voltage limiting voltage value Vt of the voltage limiting terminal VT.

[0061] In the embodiment of the present invention, Figure 5 As shown, the constant current driving module 40 may include a first op amp INV1, a third resistor R3, a first switch tube M1 and a current regulating resistor Rext. The first op amp INV1 includes a first positive input terminal, a first negative input terminal and a first amplified output terminal, the first switch tube M1 includes a first source, a first drain and a first gate, the first positive input terminal inputs a first reference voltage Vref1, the first source and the first gate are short-circuited and connected to the first amplified output terminal, the third resistor R3 is connected between the first amplified output terminal and the first negative input terminal, the current regulating resistor Rext is connected between the first source and the ground terminal, the driving input terminal 41 includes a first negative input terminal, and the first drain is used to connect the light source load 60. It can be seen that the first op amp INV1, the third resistor R3 and the current regulating resistor Rext are used as a non-inverting closed-loop amplifier in the constant current driving module 40, and the first switch tube M1 can be a MOS tube. In practical applications, if it is necessary to adjust the load operating current Iout flowing through the light source load 60, the resistance value of the current regulating resistor Rext can be adjusted, or the first reference voltage Vref1 input to the first positive input terminal can be adjusted, or the fourth resistor R4 can be adjusted. In order to facilitate proportional and fine adjustment of the load operating current Iout flowing through the light source load 60, the current regulating resistor Rext is usually set as an adjustable resistor, and the load operating current Iout is adjusted by changing the resistance value of the current regulating resistor Rext. Of course, other electronic components can also be connected to form a constant current drive module 40, which will not be repeated here.

[0062] It should be noted that the drain voltage Vth in formula (3) is Figure 5 The drain voltage of the third switch tube M3.

[0063] In the embodiment of the present invention, the negative feedback regulation module 30 includes a fourth resistor R4, a second operational amplifier INV2, a second switch tube M2 and a feedback current mirror W2. The second operational amplifier INV2 includes a second positive input terminal, a second negative input terminal and a second amplified output terminal, the second switch tube M2 includes a second source, a second drain and a second gate, the feedback current mirror W2 includes a feedback input terminal and a feedback output terminal, the second positive input terminal is input with a second reference voltage Vref2, the second source and the second gate are short-circuited and connected to the second amplified output terminal and the second negative input terminal, the fourth resistor R4 is connected between the second gate and the voltage limiting terminal VT, the second drain is connected to the feedback input terminal, and the second regulation output terminal 32 includes a feedback output terminal. Among them, the second operational amplifier INV2 is used as a non-inverting closed-loop amplifier in the negative feedback regulation module 30, and the second switch tube M2 can be a MOS tube. By utilizing the non-inverting closed-loop amplification function of the second operational amplifier INV2, the current value entering the feedback input terminal of the feedback current mirror W2 in the negative feedback regulation module 30 is negatively correlated with the voltage value of the voltage limiting terminal VT, thereby achieving the purpose of negative feedback. Among them, the current ratio of the feedback current mirror W2 can be K3, and the feedback current mirror W2 can include at least one current mirror.

[0064] Ginseng Figure 5 , the current output by the second regulating output terminal 32 of the negative feedback regulating module 30 is the second regulating output current IA2, wherein the second regulating output current IA2 is specifically obtained by the following formula:

[0065]

[0066] When the control circuit 100 is powered on, the signal sampling input voltage Vin charges the first capacitor C1 through the first resistor R1, and the voltage limiting voltage Vt on the voltage limiting terminal VT rises from 0 to a fixed value (eg Figure 6a As shown in FIG. 1 ), that is, it rises to the first threshold value. At the moment when the control circuit 100 is powered on, as mentioned above, the waveform of the first regulated output current IA1 shows an upward trend, that is, the value of the first regulated output current IA1 is positively correlated with the voltage limiting voltage value Vt (as shown in FIG. 1 ). Figure 6b As shown in formula (4), it can be seen that the waveform of the second regulated output current IA2 shows a downward trend, that is, the value of the second regulated output current IA2 is negatively correlated with the voltage limiting voltage value Vt (as shown in formula (4) Figure 6c shown).

[0067] In order to make the second regulated output current IA2 outputted by the second regulated output terminal 32 of the negative feedback regulation module 30 equal to 0 when the charge capacity of the first capacitor C1 is fully charged and reaches the first threshold, that is, after the control circuit 100 is powered on, so that the first regulated output current IA1 outputted by the first regulated output terminal 22 of the constant power regulation module 20 is equal to the current value input to the constant current driving module 40, the second reference voltage Vreft2 can be set equal to the first threshold.

[0068] like Figure 5 As shown, the first regulating output current IA1 output by the first regulating output terminal 22 of the constant power regulating module 20 and the second regulating output current IA2 output by the second regulating output terminal 32 of the negative feedback regulating module 30 are combined to form a driving input current IA3 (as shown in FIG. Figure 6d As shown in FIG. 1 ), the driving input terminal 41 is input to the constant current driving module 40. At the instant t when the control circuit 100 is powered on, since the first regulated output current IA1 is on the rise and the second regulated output current IA2 is on the fall, the driving input current IA3 can be made a fixed value by adjusting the relevant parameters of formula (1) and formula (3).

[0069] Specifically, at the moment of power-on, the first regulated output current IA1 is 0, at which time the voltage limit value is 0, and the second regulated output current IA2 is After the power-on is completed, the value of the first regulated output current IA1 should be equal to the current IA2 at the beginning of the power-on, that is:

[0070]

[0071] Moreover, the driving input current IA3 obtained by the sum of the first regulated output current IA1 and the second regulated output current IA2 should be a fixed value.

[0072] Combination Figure 5 and Figure 6a-6e It can be seen that the load working current Iout is

[0073]

[0074] When the driving input current IA3 is a fixed value, the corresponding waveform of the load working current Iout is as follows: Figure 6eAs shown, it can be seen that there is no current overshoot phenomenon in the load working current Iout during the power-on process. In the embodiment of the present invention, the control circuit 100 also includes a power supply module 50, which provides power for the signal sampling module 10, the constant power regulation module 20, the negative feedback regulation module 30 and the constant current drive module 40. Of course, the power supplies of the signal sampling module 10, the constant power regulation module 20, the negative feedback regulation module 30 and the constant current drive module 40 may not be provided by the same power supply module 50.

[0075] In the embodiment of the present invention, in order to improve the integration, the signal sampling module 10, the constant power regulation module 20, the negative feedback regulation module 30 and the constant current driving module 40 can be centrally arranged in an integrated circuit. Alternatively, at least two of the signal sampling module 10, the constant power regulation module 20, the negative feedback regulation module 30 and the constant current driving module 40 can be centrally arranged in an integrated circuit. Figure 7 As shown, after the signal sampling module 10, the constant power regulation module 20, the negative feedback regulation module 30 and the constant current driving module 40 are integrated into the chip U1, a circuit is set on the periphery of the chip U1 to provide working current for the LED light string.

[0076] In the embodiment of the present invention, the number of the constant current driving module 40 may be one.

[0077] also, Figure 5 Each switch tube in can be a MOS tube, among which M5, M6, M7 and M8 can be a P-type MOS tube, that is, the MOS tube connected to VDD is a P-type MOS tube.

[0078] Example 2

[0079] The control circuit 100 of the second embodiment of the present invention is different from the first embodiment in that: the number of constant current driving modules 40 is at least two, at least two constant current driving modules 40 are arranged in parallel, and at least two of the second drain electrodes are used to connect the light source load 60 in parallel. Figure 8 As shown, a constant current driving module where the first op amp INV1 and the first switch tube M1 are located produces a first load current Iout1, and a constant current driving module where the third op amp INV1-1 and the fourth switch tube M1-1 are located produces a second load current Iout2, so that the load working current passing through the LED light string is the sum of the first load current Iout1 and the second load current Iout2.

[0080] The control circuit 100 of the embodiment of the present invention is provided with a plurality of constant current driving modules 40 connected in parallel, which can increase the output power of the control circuit 100 and enable the control circuit 100 to have more extended functions and a wider range of applications.

[0081] Example 3

[0082] In addition, an embodiment of the present invention further provides a lighting device,

[0083] An embodiment of the present invention provides a lighting device, which includes the light source load 60 as mentioned above, and the control circuit 100 of embodiment 1 or embodiment 2. The light source load 60 is an LED light source, and since there is no current overshoot phenomenon during the power-on process of the control circuit 100, the light source load 60 in the lighting device can have a longer service life, so that the lighting device has higher reliability.

[0084] The above embodiments of the present application focus on describing the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0085] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A control circuit, characterized in that: include: Signal sampling module, constant power regulation module, negative feedback regulation module and constant current drive module; The signal sampling module includes a voltage limiting terminal, the voltage limiting terminal is used to output a voltage limiting value, and the voltage limiting value is lower than a first threshold; The constant power regulation module comprises a first regulation input terminal and a first regulation output terminal, the voltage limiting terminal is connected to the first regulation input terminal, and the output current of the first regulation output terminal is positively correlated with the input voltage of the first regulation input terminal; The negative feedback regulation module comprises a second regulation input terminal and a second regulation output terminal, the voltage limiting terminal is connected to the second regulation input terminal, and the output current of the second regulation output terminal is negatively correlated with the input voltage of the second regulation input terminal; The constant current driving module comprises a driving input terminal, and the first regulating output terminal and the second regulating output terminal are connected to the driving input terminal; The constant current driving module includes a first operational amplifier, a third resistor, a first switching tube and a current regulating resistor; the first operational amplifier includes a first positive input terminal, a first negative input terminal and a first amplified output terminal, the first switching tube includes a first source, a first drain and a first gate, the first positive input terminal inputs a first reference voltage, the first source and the first gate are short-circuited and connected to the first amplified output terminal, the third resistor is connected between the first amplified output terminal and the first negative input terminal, the current regulating resistor is connected between the first source and the ground terminal, the driving input terminal includes the first negative input terminal, and the first drain is used to connect a light source load.

2. The control circuit according to claim 1, characterized in that: The signal sampling module includes a first resistor and a first capacitor, the two ends of the first resistor are respectively connected to the signal sampling input voltage and the first capacitor, the two ends of the first capacitor are respectively connected to the first resistor and the ground end, the voltage limiting end is an endpoint located between the first resistor and the first capacitor, and the first threshold is determined by the capacitance of the first capacitor.

3. The control circuit according to claim 1, characterized in that: The constant power regulation module includes a second resistor and a constant power current mirror, the second resistor is connected between the voltage limiting end and the constant power current mirror, and the constant power current mirror is connected between the second resistor and the constant current driving module.

4. The control circuit according to claim 1, characterized in that: The negative feedback regulation module includes a fourth resistor, a second operational amplifier, a second switch tube and a feedback current mirror; the second operational amplifier includes a second positive input terminal, a second negative input terminal and a second amplification output terminal, and the second switch tube includes a second source, a second drain and a second gate; the feedback current mirror includes a feedback input terminal and a feedback output terminal; the second positive input terminal inputs a second reference voltage, the second source and the second gate are short-circuited and connected to the second amplification output terminal and the second negative input terminal, and the fourth resistor is connected between the second gate and the voltage limiting terminal; The second drain is connected to the feedback input terminal, and the second regulation output terminal includes the feedback output terminal.

5. The control circuit according to claim 4, characterized in that: The second reference voltage is equal to the first threshold.

6. The control circuit according to claim 4, characterized in that: The number of the constant current driving module is one; Or the number of the constant current driving modules is at least two, at least two of the constant current driving modules are arranged in parallel, and at least two of the second drains are used to be connected in parallel to the light source load.

7. The control circuit according to claim 1, characterized in that: The control circuit further comprises a power supply module, which provides power to the signal sampling module, the constant power regulation module, the negative feedback regulation module and the constant current driving module.

8. The control circuit according to claim 1, characterized in that: The signal sampling module, the constant power regulation module, the negative feedback regulation module and the constant current driving module are centrally arranged in an integrated circuit; or the constant power regulation module and the negative feedback regulation module are centrally arranged in an integrated circuit.

9. The control circuit according to claim 1, characterized in that: When the output voltage of the voltage-limiting terminal is between zero and the first threshold value, the sum of the output current of the first regulating output terminal and the output current of the second regulating output terminal is a constant value.

10. A lighting device, characterized in that: It comprises a light source load and a control circuit as described in any one of claims 1 to 9, wherein the light source load is an LED light source.

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