EP-4240111-B1 - CONTROL CIRCUIT AND LIGHTING DEVICE

Inventors

• CHEN, FENG
• ZHANG, Pingwei

Dates

Publication Date

20260506

Application Date

20211028

Claims (10)

1. A control circuit, comprising: a signal sampling module (10), a constant power regulation module (20), a negative feedback regulation module (30), and a constant current driving module (40); wherein the signal sampling module comprises a voltage limiting terminal (VT), the voltage limiting terminal is configured to output a limiting voltage value, and the limiting voltage value is lower than a first threshold value; 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 an output current of the first regulation output terminal is positively correlated with an input voltage of the first regulation input terminal; the negative feedback regulation module comprises a second regulation input terminal (31) and a second regulation output terminal, the voltage limiting terminal is connected to the second regulation input terminal, and an output current of the second regulation output terminal is negatively correlated with an input voltage of the second regulation input terminal; and characterised in that the constant current driving module comprises a driving input terminal, and the first regulation output terminal and the second regulation output terminal are connected to the driving input terminal, wherein the constant current driving module comprises a first operational amplifier, a third resistor, a first switching transistor, and a current regulation resistor; the first operational amplifier comprises a first positive input terminal, a first negative input terminal, and a first amplification output terminal; the first switching transistor comprises a first source electrode, a first drain electrode, and a first gate electrode; a first reference voltage is input to the first positive input terminal, the first source electrode and the first gate electrode are short-circuited and are connected to the first amplification output terminal, the third resistor is connected between the first amplification output terminal and the first negative input terminal, the current regulation resistor is connected between the first source electrode and a grounding terminal; and the driving input terminal comprises the first negative input terminal, and the first drain electrode is configured to connect a light source load.
2. The control circuit according to claim 1, wherein the signal sampling module comprises a first resistor and a first capacitor, two terminals of the first resistor are respectively connected to a signal sampling input voltage and the first capacitor, two terminals of the first capacitor are respectively connected to the first resistor and the grounding terminal, the voltage limiting terminal is an end point located between the first resistor and the first capacitor, and the first threshold value is determined by the capacitance value of the first capacitor.
3. The control circuit according to claim 1, wherein the constant power regulation module comprises a second resistor and a constant power current mirror, the second resistor is connected between the voltage limiting terminal 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, wherein the negative feedback regulation module comprises a fourth resistor, a second operational amplifier, a second switching transistor, and a feedback current mirror; the second operational amplifier comprises a second positive input terminal, a second negative input terminal, and a second amplification output terminal, and the second switching transistor comprises a second source electrode, a second drain electrode, and a second gate electrode; the feedback current mirror comprises a feedback input terminal and a feedback output terminal; a second reference voltage is input to the second positive input terminal, the second source electrode and the second gate electrode are short-circuited and are connected to the second amplification output terminal and the second negative input terminal, and the fourth resistor is connected between the second gate electrode and the voltage limiting terminal; and the second drain electrode is connected to the feedback input terminal, and the second regulation output terminal comprises the feedback output terminal.
5. The control circuit according to claim 4, wherein the second reference voltage is equal to the first threshold value.
6. The control circuit according to claim 1, wherein at least two constant current driving modules are provided, the at least two constant current driving modules are arranged in parallel, and at least two second drain electrodes are configured to connect to the light source load in parallel.
7. The control circuit according to claim 1, wherein the control circuit further comprises a power supply module (50); the power supply module is configured to supply power for 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, wherein the signal sampling module, the constant power regulation module, the negative feedback regulation module, and the constant current driving module are collectively arranged in an integrated circuit; or the constant power regulation module and the negative feedback regulation module are collectively arranged in the integrated circuit.
9. The control circuit according to claim 1, wherein in a case where an output voltage of the voltage limiting terminal is between zero and the first threshold value, a sum of the output current of the first regulation output terminal and the output current of the second regulation output terminal is a constant value.
10. A lighting device, comprising a light source load (60) and the control circuit according to any one of claims 1-9, and the light source load is a LED light source.

Description

TECHNICAL FIELD This application relates to a technical field of illumination, in particular to a control circuit and a lighting device. BACKGROUND In a lighting device, a control circuit can drive a load by using the constant power regulation technology, that is, when the input voltage of the line network is high, the output current is reduced, to keep the input power of the light source load basically unchanged. However, at present, at the moment of power-on of the constant power regulation technology, the current output to the light source load has an overshoot phenomenon, causing the light source load to be easily damaged or broken down. CN110635448A discloses an undervoltage protection circuit which comprises a power supply voltage positive correlation current generating circuit, a power supply voltage negative correlation current generating circuit, a current comparison circuit and a dynamic filter circuit. The power supply voltage positive and negative correlation current generating circuit is used for generating two paths of currents which are positively correlated and negatively correlated with the power supply voltage respectively, and the current comparison circuit is used for comparing the magnitudes of the two paths of currents to generate an undervoltage protection signal. At the same time, the current inversely related to the supply voltage can be used to realize a dynamic filtering function, i.e. the filtering time increases with the increase of the supply voltage. SUMMARY In order to solve the problem of overshoot of current on a light source load at power-on moment of a control circuit, the present application provides a control circuit and a lighting device. The invention is defined in the independent claims and further embodiments are defined in the dependent claims. The above-mentioned at least one technical solution adopted in the present invention can achieve the following beneficial effects: Compared with the prior art, in 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 current overshoot phenomenon of the light source load. In the control circuit of embodiments of the present invention, because the output current of the first regulation output terminal is positively correlated with the output voltage of the voltage limiting terminal, and the output current of the second regulation output terminal is negatively correlated with the output voltage of the voltage limiting terminal, during the power-on process of the control circuit, that is, during the voltage at the voltage limiting terminal is changed from zero 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, and the phenomenon of current overshoot generated on the light source load is avoided. BRIEF DESCRIPTION OF THE DRAWINGS The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings: FIG. 1 shows a schematic module diagram of a control circuit in the prior art;FIG. 2 shows a schematic diagram of elements included in various modules in FIG. 1;FIG. 3a shows a schematic waveform diagram of a working process Vt';FIG. 3b shows a schematic waveform diagram of a working process Iout';FIG. 3c shows a schematic waveform diagram at a moment of power-on Vt';FIG. 3d shows a schematic waveform diagram at a moment of power-on IA1';FIG. 3e shows a schematic waveform diagram at a moment of power-on Iout';FIG. 4 is a schematic module diagram of the control circuit provided by embodiment 1 of the present invention;FIG. 5 shows a schematic diagram of elements included in various modules in FIG. 4;FIG. 6a shows a schematic waveform diagram at a moment of power-on Vt in FIG. 5;FIG. 6b shows a schematic waveform diagram at a moment of power-on IA1 in FIG. 5;FIG. 6c shows a schematic waveform diagram at a moment of power-on IA2 in FIG. 5;FIG. 6d shows a schematic waveform diagram at a moment of power-on IA3 in FIG. 5;FIG. 6e shows a schematic waveform diagram at a moment of power-on Iout in FIG. 5;FIG. 7 shows a schematic diagram of an application circuit after remaining modules except for the light source load in FIG. 5 are integrated; andFIG. 8 shows a schematic element diagram of a control circuit including two parallel constant current driving modules in embodiment 2 of the present invention. Reference numerals: 100'-control circuit in the prior art; 10'-signal sampling module; 20'-constant power regulation module; 30'-constant current driving module; 40'-power suppl