Feedback circuit and control circuit for lamp load

Abstract

The invention relates to a feedback circuit and a control circuit for a lamp load, the feedback circuit is connected with a driving circuit of the lamp load, the driving circuit comprises a non-dimming chip, a semiconductor switching device and a sampling resistor, the semiconductor switching device comprises a grid electrode, a source electrode and a drain electrode, the drain electrode is connected to a negative electrode of the lamp load, and the sampling resistor is connected with the non-dimming chip. The sampling resistor is connected between the source electrode and the ground, the non-dimming chip comprises a first output terminal and a voltage feedback terminal, the first output terminal is connected to the grid electrode, the feedback circuit comprises a first divider resistor and a second divider resistor which are connected in series, the first end of the first divider resistor is connected to the negative electrode of the lamp load, and the second end of the second divider resistor is connected to the negative electrode of the lamp load. The first end of the first divider resistor is connected to the first end of the first divider resistor, the second end of the first divider resistor is connected to the source electrode, the second end of the second divider resistor is connected to the source electrode, and the voltage feedback terminal is connected to the second end of the first divider resistor, so that the technical effect that the power difference of the driving circuit under different input voltages is reduced in a low-cost and simple mode is achieved.

Description

Feedback circuit and control circuit for lamp loads Technical Field

[0001] This application relates to a drive circuit for a lamp load that includes a non-dimming chip, and more specifically, to a feedback circuit that can reduce the power difference of a constant current drive circuit including a non-dimming chip at different operating voltages, and a control circuit for a lamp load that includes the feedback circuit. Background Technology

[0002] For lamp loads, when using a constant current drive circuit without a dimming chip, the output current cannot be adjusted with voltage changes. Therefore, the operating power of the lamp load varies significantly under different AC voltage conditions (e.g., 108Vac, 120Vac, 132Vac). Typically, to ensure the drive circuit operates normally at 132Vac, its actual operating power at the nominal 120Vac condition is reduced, which in turn leads to a decrease in the drive circuit's power efficiency. Using a constant current drive circuit with a dimming chip can solve this power difference problem under different voltage conditions. However, using a dimming chip significantly increases circuit cost.

[0003] Therefore, a low-cost method is needed to reduce the power difference of the constant current drive circuit of the lamp load, including the non-dimming chip, at different operating voltages. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems. The main objective of this application is to provide a feedback circuit for a constant current drive circuit including a non-dimming chip for a lamp load, so as to solve the technical problem in the prior art that it is difficult to solve the power difference of the constant current drive circuit including a non-dimming chip under different operating voltages in a low-cost manner. In this way, the power difference of the drive circuit under different input voltages can be reduced in a low-cost and simple manner, the power utilization efficiency of the drive circuit of the lamp load can be improved, and the overall power consumption and temperature rise of the circuit can be reduced.

[0005] To achieve the above objectives, according to one aspect of this application, a feedback circuit for a lamp load is provided, which is connected to a driving circuit of the lamp load. The driving circuit includes a non-dimming chip, a semiconductor switching device, and a sampling resistor. The semiconductor switching device includes a gate, a source, and a drain. The drain of the semiconductor switching device is connected to the negative terminal of the lamp load. The sampling resistor is connected between the source of the semiconductor switching device and ground. The non-dimming chip includes a first output terminal and a voltage feedback terminal. The first output terminal is connected to the gate of the semiconductor switching device. The feedback circuit includes a first voltage divider resistor and a second voltage divider resistor connected in series. The first end of the first voltage divider resistor is connected to the negative terminal of the lamp load. The second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor. The second end of the second voltage divider resistor is connected to the source of the semiconductor switching device. The voltage feedback terminal is connected to the second end of the first voltage divider resistor.

[0006] In this way, when the input voltage at the power input terminal increases, the voltage drop across the second voltage divider resistor will increase, which leads to a decrease in the voltage drop across the sampling resistor. As a result, the current flowing through the lamp load, semiconductor switching devices, and sampling resistor decreases, thereby reducing the circuit power difference caused by different input voltages when the input voltage fluctuates. This keeps the circuit power consumption stable under different input voltages and reduces the overall power consumption and temperature rise of the circuit.

[0007] Furthermore, according to one embodiment of this application, the non-dimming chip further includes a first input terminal and a ground terminal. The first input terminal is connected to the power input terminal, and the driving circuit further includes a first capacitor and a second capacitor. The first capacitor is connected in parallel with the lamp load, and the two ends of the second capacitor are respectively connected to the first input terminal and the ground terminal.

[0008] In this way, non-dimming chips and semiconductor switching devices can maintain the sum of the voltage drop across the sampling resistor and the voltage drop across the second voltage divider resistor at a preset fixed threshold, so that the current flowing through the sampling resistor can decrease as the input voltage increases.

[0009] Furthermore, according to one embodiment of this application, the semiconductor switching device is a metal-oxide-semiconductor field-effect transistor.

[0010] In this way, the conduction level of the semiconductor switching device can be adjusted based on the difference between the sampled voltage and the preset threshold voltage, thereby adjusting the magnitude of the current flowing through the sampling resistor.

[0011] Furthermore, according to one embodiment of this application, either the first voltage divider resistor or the second voltage divider resistor is composed of one or more resistors.

[0012] In this way, fixed resistors can be flexibly combined to achieve a first voltage divider resistor and a second voltage divider resistor with the desired resistance value.

[0013] Furthermore, according to one embodiment of this application, the non-dimming chip has a built-in voltage comparator and a control loop. The voltage comparator is configured to compare the sampled voltage input from the voltage feedback terminal with a preset threshold voltage and output the comparison result. The control loop is configured to adjust the voltage at the first output terminal using the comparison result.

[0014] According to another aspect of this application, a feedback circuit for a lamp load is provided, connected to a driving circuit of the lamp load. The driving circuit includes a non-dimming chip, a semiconductor switching device, and a sampling resistor. The semiconductor switching device includes a gate, a source, and a drain. The drain of the semiconductor switching device is connected to the negative terminal of the lamp load, and the positive terminal of the lamp load is connected to a power input terminal. The sampling resistor is connected between the source of the semiconductor switching device and ground. The non-dimming chip includes a first output terminal and a voltage feedback terminal. The first output terminal is connected to the gate of the semiconductor switching device. The feedback circuit includes a first voltage divider resistor and a second voltage divider resistor. A first end of the first voltage divider resistor is connected to the power input terminal, and a second end of the first voltage divider resistor is connected to the positive terminal of the lamp load. A first end of the second voltage divider resistor is connected to the drain of the semiconductor switching device, and a second end of the second voltage divider resistor is connected to the source of the semiconductor switching device. The voltage feedback terminal is connected to the second end of the first voltage divider resistor.

[0015] In this way, when the input voltage at the power input terminal increases, the voltage drop across the second voltage divider resistor will increase, which leads to a decrease in the voltage drop across the sampling resistor. As a result, the current flowing through the lamp load, semiconductor switching devices, and sampling resistor decreases, thereby reducing the circuit power difference caused by different input voltages when the input voltage fluctuates. This keeps the circuit power consumption stable under different input voltages and reduces the overall power consumption and temperature rise of the circuit.

[0016] Furthermore, according to one embodiment of this application, the non-dimming chip further includes a first input terminal and a ground terminal. The first input terminal is connected to the power input terminal, and the driving circuit further includes a first capacitor and a second capacitor. The first capacitor is connected in parallel with the lamp load, and the two ends of the second capacitor are respectively connected to the first input terminal and the ground terminal.

[0017] According to another aspect of this application, a control circuit for a lamp load is provided, the control circuit comprising: the aforementioned feedback circuit for the lamp load; and the aforementioned drive circuit for the lamp load, connected to the feedback circuit.

[0018] In this embodiment, a feedback circuit for a lamp load is provided, which is connected to the driving circuit of the lamp load. The driving circuit includes a non-dimming chip, a semiconductor switching device, and a sampling resistor. The semiconductor switching device includes a gate, a source, and a drain. The drain of the semiconductor switching device is connected to the negative terminal of the lamp load. The sampling resistor is connected between the source of the semiconductor switching device and ground. The non-dimming chip includes a first output terminal and a voltage feedback terminal. The first output terminal is connected to the gate of the semiconductor switching device. The feedback circuit includes a first voltage divider resistor and a second voltage divider resistor connected in series. The first end of the first voltage divider resistor is connected to the negative terminal of the lamp load, the second end of the first voltage divider resistor is connected to the first end of the second voltage divider resistor, and the second end of the second voltage divider resistor is connected to the source of the semiconductor switching device. The voltage feedback terminal is connected to the second end of the first voltage divider resistor. This provides at least a solution to the technical problem in the prior art that it is difficult to solve the power difference of the constant current driving circuit including the non-dimming chip under different operating voltages in a low-cost manner. This achieves the technical effects of reducing the power difference of the driving circuit under different input voltages, improving the power utilization efficiency of the driving circuit of the lamp load, and reducing the overall power consumption and temperature rise of the circuit in a low-cost and simple manner. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0020] Figure 1 is a schematic diagram of a conventional constant current drive circuit for lamp loads, including a non-dimming chip.

[0021] Figure 2 is a schematic diagram showing the changes of input voltage and current over time in the constant current drive circuit shown in Figure 1.

[0022] Figure 3 is a schematic diagram of a feedback circuit for a lamp load and a control circuit including the same, according to a first embodiment of this application;

[0023] Figure 4 is a schematic diagram showing the changes of input voltage and current over time in the control circuit for lamp load shown in Figure 3.

[0024] Figure 5 is a schematic diagram of a feedback circuit for a lamp load and a control circuit including the same, according to a first exemplary embodiment of this application;

[0025] Figure 6 shows the measurement results of the voltage waveforms at each node of the circuit under the control circuit shown in Figure 5;

[0026] Figure 7 shows the actual measured power consumption of the circuit under the constant current drive circuit shown in Figure 1 and the actual measured power consumption of the circuit under the control circuit shown in Figure 5;

[0027] Figure 8 is a schematic diagram of a feedback circuit for a lamp load and a control circuit including the same, according to a second embodiment of this application.

[0028] The above figures include the following reference numerals:

[0029] 100': Constant current drive circuit

[0030] 100, 100”: Drive circuit

[0031] 110: Non-dimming chip

[0032] 1101: First output terminal

[0033] 1102: Voltage feedback terminal

[0034] 1103: First input terminal

[0035] 1104: Grounding terminal

[0036] 120: Semiconductor switching devices

[0037] 120D: Drain

[0038] 120G: Gate

[0039] 120S: Source

[0040] 130: Sampling resistor

[0041] 140: First capacitor

[0042] 150: Second capacitor

[0043] 200: Lamp load

[0044] 300, 300”: Feedback circuit

[0045] 310: First voltage divider resistor

[0046] 320: Second voltage divider resistor

[0047] 400, 400”: Control circuit

[0048] Vin: Input voltage

[0049] VF: On-state voltage

[0050] Vth, Vth': Threshold voltage

[0051] Vsa: Sample voltage

[0052] V_130: Voltage drop across the sampling resistor

[0053] V_200_C: Voltage at the negative terminal of the lamp load.

[0054] V_320: Voltage drop across the second voltage divider resistor Detailed Implementation

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0057] In this application, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this application.

[0058] First, a conventional constant current drive circuit 100' for a lamp load, including a non-dimming chip, will be described with reference to Figures 1 and 2. As shown in Figure 1, the conventional constant current drive circuit 100' includes a non-dimming chip 110, a semiconductor switching device (e.g., a MOSFET) 120, and a sampling resistor 130. The drain of the semiconductor switching device 120 is connected to the negative terminal of the lamp load 200 (e.g., one or more LEDs), and the sampling resistor 130 is connected between the source of the semiconductor switching device 120 and ground. The non-dimming chip 110 includes a first output terminal 1101 connected to the gate of the semiconductor switching device 120, and the voltage feedback terminal 1102 connected between the sampling resistor 130 and the source of the semiconductor switching device 120. In addition, the positive terminal of the lamp load 200 is also connected to the power input terminal (e.g., via a rectifier and driver), the lamp load 200 is also connected in parallel with the first capacitor 140, and the two ends of the second capacitor 150 are respectively connected to the first input terminal 1103 and the ground terminal 1104 of the non-dimming chip 110.

[0059] In this constant current drive circuit 100', when the input voltage Vin at the power input terminal is greater than the conduction voltage VF of the lamp load, the first input terminal 1103 of the non-dimming chip 110 is connected to the power input terminal through a resistor voltage divider (as shown by R3 and R4 in the figure). The non-dimming chip 110 controls the voltage at the first output terminal 1101 according to the voltage at the first input terminal 1103, so the first output terminal 1101 is continuously controlled to a high level, and the semiconductor switching device 120 is turned on. At this time, the positive voltage of the lamp load 200 is greater than the negative voltage, and the lamp load 200 is turned on. At this time, the driving current of the lamp load 200 is controlled by the sampling resistor 130 (the non-dimming chip 110 compares the sampled voltage at the voltage feedback terminal 1102 with a predetermined threshold voltage, and controls the conduction degree of the semiconductor switching device 120 according to the voltage difference between the sampled voltage and the predetermined threshold voltage so that the voltage at the voltage feedback terminal 1102 approaches the predetermined threshold voltage. The threshold voltage compared with the sampled voltage at the voltage feedback terminal 1102 is, for example, 0.2V, and the resistance value of the sampling resistor 130 is fixed). When the input voltage Vin is less than the lamp load's turn-on voltage VF, the non-dimming chip can continue to work because the second capacitor 150 can provide freewheeling current, so the first output terminal 1101 remains at a high level, causing the semiconductor switching device 120 to turn on. At this time, since the input voltage is insufficient to support the lamp load 200 to turn on, the first capacitor 140 provides a freewheeling operating voltage to the lamp load 200. In the constant current drive circuit 100', since the conduction degree of the semiconductor switching device 120 is affected by the difference between the sampling voltage of the voltage feedback terminal 1102 and the threshold voltage, the conduction degree of the semiconductor switching device 120 (i.e., the current flowing through it and the sampling resistor 130) is controlled so that the voltage drop across the sampling resistor 130 (i.e., the sampling voltage at the voltage feedback terminal 1102) approaches the threshold voltage. In other words, the current flowing through the semiconductor switching device 120 and the sampling resistor 130 cannot be adjusted with changes in the input voltage. Specifically, when the AC input voltage is 108Vac, 120Vac, and 132Vac, the operating power of the circuit differs significantly under different AC voltage conditions, as shown in Figure 2. This is because the on-state voltage VF of the lamp load is fixed. Therefore, compared to the 108Vac condition, under the 132Vac condition, the lamp load 200 will turn on earlier and turn off later, meaning the conduction angle of the lamp load 200 is larger. Furthermore, since the operating voltage is higher at 132Vac, the lamp load 200 will generate higher power at the same current. To ensure that the constant current drive circuit 100' can operate normally under 132Vac conditions, its actual operating power under the nominal 120Vac condition is usually reduced, which in turn leads to a decrease in the power utilization efficiency of the drive circuit 100'.

[0060] This application aims to solve the aforementioned problems existing in conventional constant current drive circuits that include non-dimming chips. The purpose of this application is to provide a feedback circuit for a lamp load, a control circuit including the same, and a lamp fixture including the control circuit, which can reduce the power difference of the lamp load drive circuit under different operating voltages in a low-cost and simple manner. Next, the feedback circuit for a lamp load and the control circuit including the same according to a first embodiment of this application will be described with reference to FIGS. 3 to 7.

[0061] Figure 3 is a schematic diagram of a feedback circuit 300 for a lamp load and a control circuit 400 including the same according to a first embodiment of this application. Figure 4 is a schematic diagram showing the changes in input voltage and current over time in the control circuit 400 for the lamp load shown in Figure 3. As shown in Figure 3, the feedback circuit 300 for a lamp load 200 according to the first embodiment of this application is connected to the drive circuit 100 of the lamp load 200. The control circuit 400 for a lamp load 200 according to an embodiment of this application includes the feedback circuit 300 and the drive circuit 100. The driving circuit 100 includes a non-dimming chip 110, a semiconductor switching device 120, and a sampling resistor 130. The semiconductor switching device 120 includes a gate 120G, a source 120S, and a drain 120D. The drain 120D of the semiconductor switching device 120 is connected to the negative terminal of the lamp load 200, and the positive terminal of the lamp load 200 is connected to the power input terminal. The sampling resistor 130 is connected between the source 120S of the semiconductor switching device 120 and ground. The non-dimming chip 110 includes a first output terminal 1101 and a voltage feedback terminal 1102. The first output terminal 1101 is connected to the gate 120G of the semiconductor switching device 120. The feedback circuit 300 includes a first voltage divider resistor 310 and a second voltage divider resistor 320 connected in series. The first end of the first voltage divider resistor 310 is connected to the negative terminal of the lamp load 200, the second end of the first voltage divider resistor 310 is connected to the first end of the second voltage divider resistor 320, and the second end of the second voltage divider resistor 320 is connected to the source of the semiconductor switching device 120 and the non-grounded terminal of the sampling resistor 130. The voltage feedback terminal 1102 of the non-dimming chip 110 is connected to the second end of the first voltage divider resistor 310.

[0062] In this way, by adding a feedback circuit 300 and changing the connection position (i.e., voltage sampling position) of the voltage feedback terminal 1102 of the non-dimming chip 110 to be connected between the first voltage divider resistor 310 and the second voltage divider resistor 320, the voltage feedback terminal 1102 samples not the voltage drop V_130 on the sampling resistor 130 in conventional technology, but the sum of the voltage drop V_130 on the sampling resistor 130 and the voltage drop V_320 on the second voltage divider resistor 320.

[0063] In this application, the non-dimming chip 110 is configured to compare the sampled voltage Vsa input from the voltage feedback terminal 1102 with a preset threshold voltage Vth (which is a preset value, for example, 0.6V), and use the comparison result to adjust the voltage at the first output terminal 1101, thereby controlling the conduction level of the semiconductor switching device 120. Since the conduction level of the semiconductor switching device 120 affects the current I through the loop of the lamp load, itself, and the sampling resistor 130, and the conduction level of the semiconductor switching device 120 is adjusted according to the difference between the sampled voltage Vsa and the preset threshold voltage Vth, the result of the above control is that the sampled voltage Vsa at the voltage feedback terminal 1102 is equal to the preset threshold voltage Vth, that is, the resistance value of the sampling resistor R_130*I+V_320=threshold voltage Vth. In this application, the threshold voltage Vth is a fixed value preset as needed.

[0064] In the example shown in Figure 3, when the input voltage Vin (which is an AC voltage) at the power input terminal is greater than the turn-on voltage VF of the lamp load 200, the lamp load 200 is turned on, and the voltage at the negative terminal of the lamp load 200 will change with the waveform of the input voltage Vin. The voltage at this negative terminal of the lamp load 200 is divided by the first voltage divider resistor 310, the second voltage divider resistor 320, and the sampling resistor 130.

[0065] During power supply, the actual input voltage at the power input terminal fluctuates within a certain range above and below the nominal value. For example, with a nominal AC voltage of 120V for a lamp load, the actual input AC voltage may fluctuate between 108V and 132V. Therefore, when the input voltage Vin increases, the voltage shared by the first voltage divider resistor 310 and the second voltage divider resistor 320 will increase. Due to the limitation of R_130*I+V_320=Vth, this leads to a decrease in the voltage shared by the sampling resistor 130. Consequently, the current I flowing through the lamp load 200, the semiconductor switching device 120, and the sampling resistor 130 decreases, as shown in Figure 4. Here, considering that the resistance values ​​of the voltage divider resistors 310 and 320 are much larger than the resistance value of the sampling resistor 130, the current flowing through the first voltage divider resistor 310 and the second voltage divider resistor 320 is ignored. Because the current I decreases, even if the input voltage Vin increases, the power consumption of the drive circuit 100 remains essentially unchanged. Correspondingly, when the input voltage Vin decreases, the voltage shared by the first voltage divider resistor 310 and the second voltage divider resistor 320 will decrease, resulting in an increase in the voltage shared by the sampling resistor 130. Therefore, the current I flowing through the circuit of the lamp load 200, the semiconductor switching device 120 and the sampling resistor 130 also increases, so the power consumption of the drive circuit 100 remains basically unchanged.

[0066] Therefore, by utilizing the feedback circuit 300 for the lamp load 200, the power difference caused by different input voltages can be reduced through feedback control when the input voltage Vin fluctuates, thus stabilizing the power consumption of the circuit under different input voltages. Compared with conventional drive circuits, this reduces the overall power consumption and temperature rise of the drive circuit. Furthermore, this method eliminates the need to ensure the circuit operates normally under 132Vac conditions, as is done in traditional methods, thereby reducing its actual operating power under the nominal 120Vac condition and improving the power utilization efficiency of the lamp load drive circuit 100. In addition, the feedback circuit 300 for the lamp load 200 consists of only two voltage divider resistors, making it inexpensive and with a simple circuit connection structure. This achieves the effect of reducing the power difference of the drive circuit 100 under different input voltages in a low-cost and simple manner.

[0067] Figure 5 is a schematic diagram of a feedback circuit for a lamp load and a control circuit including the same, according to a first exemplary embodiment of this application. Figure 5 shows an exemplary embodiment of the control circuit 400 shown in Figure 3. As shown in Figure 5, the non-dimming chip 110 may further include a first input terminal 1103 and a ground terminal 1104, the first input terminal 1103 being connected to a power input terminal and the ground terminal 1104 being connected to ground. The drive circuit 100 may further include a first capacitor 140 and a second capacitor 150, the first capacitor 140 being connected in parallel with the lamp load 200, and a resistor (shown as R2 in the figure) may also be connected in parallel with the first capacitor 140 to form a charging and discharging circuit. The two ends of the second capacitor 150 may be connected to the first input terminal 1103 and the ground terminal 1104 of the non-dimming chip 110, respectively. The voltage at the first output terminal 1101 of the non-dimming chip 110 is also positively correlated with the input voltage at the first input terminal 1103. Therefore, when the input voltage Vin at the power input terminal is high, the voltage supplied from the first output terminal 1101 to the gate 120G of the semiconductor switching device 120 is also high, and the semiconductor switching device 120 is turned on. The degree of conduction is adjusted according to the difference between the sampled voltage Vsa and the preset threshold voltage Vth. In this application, the first capacitor 140 and the second capacitor 150 can be electrolytic capacitors.

[0068] Furthermore, the non-dimming chip 110 may have a built-in voltage comparator and control loop (not shown). The voltage comparator is connected to the voltage feedback terminal 1102 and can be configured to compare the sampled voltage Vsa input from the voltage feedback terminal 1102 with the threshold voltage Vth and output the comparison result. The control loop can be configured to adjust the voltage at the first output terminal 1101 using the comparison result. Voltage comparators and control loops with the above functions are well known to those skilled in the art and will not be described in detail here.

[0069] Furthermore, either the first voltage divider resistor 310 or the second voltage divider resistor 320 can be composed of one or more resistors. The resistance values ​​of the first voltage divider resistor 310 and the second voltage divider resistor 320 can be adjusted according to the resistance value of the sampling resistor 130, the input voltage, the conduction voltage of the lamp load 200, the expected circuit power consumption, etc. Preferably, the resistance value of the first voltage divider resistor 310 is much larger than the resistance value of the second voltage divider resistor 320, and the resistance value of the second voltage divider resistor 320 is much larger than the resistance value of the sampling resistor 130.

[0070] In this application, the semiconductor switching device 120 includes any one of a metal-oxide-semiconductor field-effect transistor (MOS transistor), a bipolar transistor, an insulated gate bipolar transistor, an electrostatic discharge transistor, etc. In the example of FIG5, the semiconductor switching device 120 is shown as an N-type MOS transistor, but this application is not limited thereto.

[0071] Next, referring to Figures 6 and 7, the actual measurement results of the voltage waveforms and circuit power consumption at each node in the control circuit 400 are described with reference to the feedback circuit 300 and control circuit 400 shown in Figure 5. Figure 6 shows the measurement results of the voltage waveforms at each node of the circuit with the control circuit shown in Figure 5. During the test, the resistance of the sampling resistor 130 was approximately 6Ω, the resistance of the first voltage divider resistor 310 was approximately 500KΩ, the resistance of the second voltage divider resistor 310 was approximately 0.75KΩ, the on-state voltage of the lamp load 200 was approximately 70V, the input voltage at the power input terminal was approximately 200V, and the threshold voltage Vth was approximately 0.2V.

[0072] As shown in Figure 6, Figure 6(a) shows the waveform of the input voltage Vin at the power input terminal, Figure 6(b) shows the waveform of the voltage V_200_C at the negative terminal of the lamp load 200, Figure 6(c) shows the waveform of the sampling voltage Vsa at the voltage feedback terminal 1102 of the non-dimming chip 110, and Figure 6(d) shows the waveforms of the voltage drop V_320 across the second voltage divider resistor 320 and the voltage drop V_130 across the sampling resistor 130. It can be seen from Figure 6 that in this circuit, the sampling voltage Vsa at the voltage feedback terminal 1102 is basically stable at the set threshold voltage Vth.

[0073] Figure 7 shows the actual measured power consumption of the circuit under the constant current drive circuit shown in Figure 1 and the actual measured power consumption of the circuit under the control circuit shown in Figure 5. The lower part of Figure 7 shows the measured results of the input voltage Vin (Urms1), the measured results of the current I through the sampling resistor 130 (Irms1), and the measured results of the power consumed by the circuit (P1) in the case of the control circuit 400 shown in Figure 5. It can be seen that as the input voltage increases from 120V to 132V, the current decreases instead, so that the power consumed by the circuit stabilizes at around 2W.

[0074] In contrast, the upper part of Figure 7 shows the measurement results of the input voltage Vin (Urms1), the current I through the sampling resistor 130 (Irms1), and the power consumed by the circuit (P1) in the case of the conventional constant current drive circuit 100' shown in Figure 1. It can be seen that in the case of the conventional constant current drive circuit 100', the power consumed by the circuit increases significantly as the input voltage increases.

[0075] Figure 8 is a schematic diagram of a feedback circuit 300” for a lamp load and a control circuit 400” including the same, according to a second embodiment of this application. In the first embodiment of this application, the voltage feedback terminal 1102 of the non-dimming chip 110 samples the remaining voltage after passing through the lamp load 200; while in the second embodiment of this application, the voltage feedback terminal 1102 of the non-dimming chip 110 samples the input voltage before passing through the lamp load 200.

[0076] As shown in Figure 8, in the second embodiment of this application, the driving circuit 100” of the lamp load 200 includes a non-dimming chip 110, a semiconductor switching device 120, and a sampling resistor 130. The semiconductor switching device 120 includes a gate 120G, a source 120S, and a drain 120D. The drain 120D of the semiconductor switching device 120 is connected to the negative terminal of the lamp load 200. The sampling resistor 130 is connected between the source 120S of the semiconductor switching device 120 and ground. The non-dimming chip 110 includes a first output terminal 1101 and a voltage feedback terminal 1102. The first output terminal 1101 is connected to the semiconductor switching device 120. The gate 120G. The feedback circuit 300 for the lamp load 200 according to the second embodiment of this application includes a first voltage divider resistor 310 and a second voltage divider resistor 320. The first end of the first voltage divider resistor 310 is connected to the power input terminal, and the second end of the first voltage divider resistor 310 is connected to the positive terminal of the lamp load 200. The first end of the second voltage divider resistor 320 is connected to the drain 120D of the semiconductor switching device 120, and the second end of the second voltage divider resistor 320 is connected to the source 120S of the semiconductor switching device 120. The voltage feedback terminal 1102 of the non-dimming chip 110 is connected to the second end of the first voltage divider resistor 310.

[0077] In this manner, the voltage sampled by the voltage feedback terminal 1102 is the sum of the voltage drop V_200 across the lamp load 200, the voltage drop V_320 across the second voltage divider resistor 320, and the voltage drop V_130 across the sampling resistor 130 (which is equal to the current I multiplied by the resistance R_130). By setting an appropriate threshold voltage Vth', when the input voltage Vin is greater than the turn-on voltage of the lamp load 200, the result after feedback control is: V_200 + V_320 + I × R_130 = Vth'. Similar to the first embodiment, when the input voltage Vin increases, the voltage drop V_320 across the second voltage divider resistor 320 will increase, thus the voltage drop V_130 across the sampling resistor 130 will decrease, resulting in a decrease in the current I flowing through the lamp load 200, the semiconductor switching device 120, and the sampling resistor 130. Because the current I decreases, the power consumption of the drive circuit 100” will remain essentially unchanged.

[0078] Therefore, the feedback circuit 300” according to the second embodiment can also reduce the circuit power difference caused by different input voltages when the input voltage Vin fluctuates, so that the circuit power consumption under different input voltages remains stable, thereby reducing the overall power consumption and temperature rise of the circuit.

[0079] Furthermore, this application also provides a lamp fixture including a control circuit 400 or 400” according to the present application as described with reference to Figures 3 to 8 and a lamp load 200. This lamp fixture is also capable of reducing the circuit power difference caused by different input voltages when the input voltage at the power input terminal of the lamp fixture fluctuates, thereby keeping the circuit power consumption stable under different input voltages, and thus reducing the overall power consumption and temperature rise of the circuit.

[0080] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0081] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0082] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A feedback circuit for a lamp load, connected to a driving circuit (100) of the lamp load (200), the driving circuit (100) comprising a non-dimming chip (110), a semiconductor switching device (120), and a sampling resistor (130), the semiconductor switching device (120) comprising a gate, a source, and a drain, the drain of the semiconductor switching device (120) being connected to the negative terminal of the lamp load (200), the sampling resistor (130) being connected between the source of the semiconductor switching device (120) and ground, the non-dimming chip (110) comprising a first output terminal (1101) and a voltage feedback terminal (1102), the first output terminal (1101) being connected to the gate of the semiconductor switching device (120), characterized in that, The feedback circuit (300) includes a first voltage divider resistor (310) and a second voltage divider resistor (320) connected in series. The first end of the first voltage divider resistor (310) is connected to the negative terminal of the lamp load (200), the second end of the first voltage divider resistor (310) is connected to the first end of the second voltage divider resistor (320), and the second end of the second voltage divider resistor (320) is connected to the source of the semiconductor switching device (120). The voltage feedback terminal (1102) is connected to the second end of the first voltage divider resistor (310).

2. The feedback circuit for a lamp load according to claim 1, characterized in that, The non-dimming chip also includes a first input terminal and a ground terminal. The first input terminal is connected to the power input terminal. The driving circuit also includes a first capacitor and a second capacitor. The first capacitor is connected in parallel with the lamp load, and the two ends of the second capacitor are respectively connected to the first input terminal and the ground terminal.

3. The feedback circuit for a lamp load according to claim 1, characterized in that, The semiconductor switching device is a metal-oxide-semiconductor field-effect transistor.

4. The feedback circuit for a lamp load according to claim 1, characterized in that, Either the first voltage divider resistor or the second voltage divider resistor is composed of one or more resistors.

5. The feedback circuit for a lamp load according to claim 1, characterized in that, The non-dimming chip has a built-in voltage comparator and a control loop. The voltage comparator is configured to compare the sampled voltage input from the voltage feedback terminal with a preset threshold voltage and output the comparison result. The control loop is configured to adjust the voltage at the first output terminal using the comparison result.

6. A control circuit for a lamp load, characterized in that, The control circuit includes: a feedback circuit for a lamp load according to any one of claims 1 to 5; and the drive circuit for the lamp load, connected to the feedback circuit.

7. A feedback circuit for a lamp load, connected to a driving circuit (100”) of a lamp load (200), the driving circuit (100”) comprising a non-dimming chip (110), a semiconductor switching device (120), and a sampling resistor (130), the semiconductor switching device (120) comprising a gate, a source, and a drain, the drain of the semiconductor switching device (120) being connected to the negative terminal of the lamp load (200), the positive terminal of the lamp load (200) being connected to a power input terminal, the sampling resistor (130) being connected between the source of the semiconductor switching device (120) and ground, the non-dimming chip (110) comprising a first output terminal (1101) and a voltage feedback terminal (1102), the first output terminal (1101) being connected to the gate of the semiconductor switching device (120), characterized in that, The feedback circuit (300”) includes: a first voltage divider resistor (310) and a second voltage divider resistor (320). The first end of the first voltage divider resistor (310) is connected to the power input terminal, and the second end of the first voltage divider resistor (310) is connected to the positive terminal of the lamp load (200). The first end of the second voltage divider resistor (320) is connected to the drain of the semiconductor switching device (120), and the second end of the second voltage divider resistor (320) is connected to the source of the semiconductor switching device (120). The voltage feedback terminal (1102) is connected to the second end of the first voltage divider resistor (310).

8. The feedback circuit for a lamp load according to claim 7, characterized in that, The non-dimming chip also includes a first input terminal and a ground terminal. The first input terminal is connected to the power input terminal. The driving circuit also includes a first capacitor and a second capacitor. The first capacitor is connected in parallel with the lamp load, and the two ends of the second capacitor are respectively connected to the first input terminal and the ground terminal.

9. A control circuit for a lamp load, characterized in that, The control circuit includes: a feedback circuit for a lamp load according to claim 7 or 8, and the drive circuit for the lamp load, connected to the feedback circuit.

Images