Driving power supply with fine dimming scales

Abstract

The invention relates to the technical field of driving power supplies, in particular to a driving power supply with fine dimming scales, a dimming output module is integrated and coupled with a dimming chip U1 with double dimming channels and a peripheral circuit of the dimming chip U1, and a controller is electrically connected with the dimming chip U1 and outputs an analog dimming signal and a chopping dimming signal to the dimming chip U1; when the analog dimming signal is adjusted to the minimum, the chopping dimming signal intervenes in dimming; the negative electrode of the output end of the dimming output module is electrically connected with the controller through the amplification detection module and the first partial pressure detection module. The controller reads detection data from the first partial pressure detection module and compares the detection data with a preset boundary value; when the detection data is larger than a preset boundary value, the data read from the first partial pressure detection module is selected, and otherwise, the data read from the amplification detection module is selected; the problems that a traditional driving power supply is difficult to expand a smaller dimming scale and the detection accuracy of the on-load output voltage cannot be ensured after expansion are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of driving power supplies, in particular to a driving power supply with fine dimming scale. Background Art

[0002] For traditional driver power supplies (such as DALI dimming constant-current power supplies), the load output voltage range is generally 0.6Vout to 1.0Vout. For example, if the Vbus output of the front-stage flyback module is 60V, the load output voltage range of the BUCK dimming output module to the lamp is generally 24V to 40V. To facilitate the detection of the load output voltage value, the selected voltage value is relatively large. However, this only achieves 1% dimming, which is very limited and can only be used in daily use scenarios. When used in medical lighting or scientific research lighting, which requires high-precision dimming, a driver power supply with a smaller dimming scale is required to achieve a softer dimming transition and a richer dimming range.

[0003] However, setting smaller dimming steps requires expanding the load output voltage range of traditional driver power supplies. To ensure the load output voltage does not exceed the specified value (overvoltage damage to the lamp), this is typically done to a lower load output voltage (for example, from 2.5V to 49V). However, lower load output voltages are prone to inaccurate detection (especially below 24V), leading to inaccurate short-circuit and overvoltage detection. Currently, no driver power supply can achieve a smaller dimming step (i.e., less than 1% dimming, such as 1 / 10,000 dimming) while ensuring accurate load output voltage detection. Summary of the Invention

[0004] In response to the above-mentioned defects, the purpose of the present invention is to propose a driving power supply with a fine dimming scale, which solves the problem that traditional driving power supplies are difficult to expand to a smaller dimming scale and cannot guarantee the accuracy of load output voltage detection after expansion.

[0005] To achieve this object, the present invention adopts the following technical solutions: A driver power supply with fine dimming scale includes a dimming output module and a controller; the dimming output module is integrated with a dimming chip U1 with dual dimming channels and its peripheral circuits, and also includes an amplification detection module and a first voltage divider detection module; the controller is electrically connected to the dimming chip U1 and outputs an analog dimming signal and a chopping dimming signal to the dimming chip U1; when the analog dimming signal is adjusted to the lowest value, the chopping dimming signal intervenes for dimming; The negative electrode of the output end of the dimming output module is electrically connected to the controller via the amplification detection module, and the negative electrode of the output end of the dimming output module is also electrically connected to the controller via the first voltage divider detection module; the amplification detection module is used for large-load output voltage detection, and the first voltage divider detection module is used for light-load output voltage detection; The controller reads detection data from the first voltage divider detection module and compares it with a preset threshold value; when the detection data is greater than the preset threshold value, the controller selects the data read from the first voltage divider detection module; when the detection data is less than or equal to the preset threshold value, the controller selects the data read from the amplification detection module.

[0006] Furthermore, it also includes a subtractor detection module and a second voltage divider detection module; the negative output terminal of the dimming output module is also electrically connected to the dimming chip U1 via the subtractor detection module, and the negative output terminal of the dimming output module is also electrically connected to the controller via the second voltage divider detection module.

[0007] Furthermore, it also includes a ghost fire switch module; the negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the amplification detection module, and is electrically connected to the controller; the negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the first voltage divider detection module, and is electrically connected to the controller; The negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the subtractor detection module, and is electrically connected to the dimming chip U1; the negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the second voltage divider detection module, and is electrically connected to the controller; The ghost fire switch module is electrically connected to the controller; the ghost fire switch module is used to disconnect the circuit passing through the ghost fire switch module under the control of the controller when the driving power supply is on standby.

[0008] Furthermore, the ghost fire switch module includes a resistor R44, a resistor R37, a transistor Q4 and a transistor Q5; one end of the resistor R44 is electrically connected to the controller, the other end of the resistor R44 is electrically connected to the base of the transistor Q5, the emitter of the transistor Q5 is connected to the SGND ground terminal, the collector of the transistor Q5 is electrically connected to the base of the transistor Q4 via the resistor R37, the emitter of the transistor Q4 is electrically connected to the negative output terminal of the dimming output module, and the amplification detection module, the first voltage divider detection module, the subtractor detection module, and the second voltage divider detection module are all electrically connected to the collector of the transistor Q4.

[0009] Furthermore, the subtractor detection module includes a module shutdown unit, an operational amplifier U4B, a resistor R50, a resistor R56, a resistor R62, a resistor R69, a resistor R70, a resistor R63, a resistor R67, a resistor R71 and a diode D11; one end of the resistor R63 is electrically connected to the negative electrode of the output end of the dimming output module, the other end of the resistor R63 is electrically connected to one end of the resistor R67, the other end of the resistor R67 and one end of the resistor R71 are both electrically connected to one end of the resistor R70, the other end of the resistor R71 is connected to the SGND ground terminal, the other end of the resistor R70 and one end of the resistor R69 are both electrically connected to the negative input terminal of the operational amplifier U4B, the other end of the resistor R69 and the anode of the diode D11 are both electrically connected to the output end of the operational amplifier U4B, and the cathode of the diode D11 is electrically connected to the dimming chip U1; The power supply voltage is electrically connected to one end of the resistor R50 via the module shutdown unit, and the other end of the resistor R50 is electrically connected to one end of the resistor R56; the other end of the resistor R56 and one end of the resistor R62 are both electrically connected to the positive input terminal of the operational amplifier U4B, and the other end of the resistor R62 is connected to the SGND ground terminal; The module closing unit is electrically connected to the controller; the module closing unit is used to disconnect the circuit passing through the module closing unit under the control of the controller when the driving power supply is on standby.

[0010] Furthermore, the module shutdown unit includes a resistor R49, a resistor R46, a transistor Q6 and a transistor Q7; one end of the resistor R49 is electrically connected to the controller, the other end of the resistor R49 is electrically connected to the base of the transistor Q7, the emitter of the transistor Q7 is connected to the SGND ground terminal, the collector of the transistor Q7 is electrically connected to the base of the transistor Q6 via the resistor R46, the emitter of the transistor Q6 is connected to the power supply voltage, and the collector of the transistor Q6 is electrically connected to one end of the resistor R50.

[0011] Furthermore, the amplification and detection module includes an operational amplifier U4A, a resistor R65, a resistor R66, a resistor R51, a resistor R53, and a resistor R57; one end of the resistor R51 is used to be electrically connected to the negative electrode of the output terminal of the dimming output module, the other end of the resistor R51 is electrically connected to one end of the resistor R53, the other end of the resistor R53 and one end of the resistor R57 are both electrically connected to the positive input terminal of the operational amplifier U4A, and the other end of the resistor R57 is connected to the SGND ground terminal; The output end of the operational amplifier U4A is electrically connected to the controller, the output end of the operational amplifier U4A is electrically connected to one end of the resistor R65, the other end of the resistor R65 and one end of the resistor R66 are both electrically connected to the negative input end of the operational amplifier U4A, and the other end of the resistor R66 is connected to the SGND ground end.

[0012] Furthermore, the first voltage division detection module includes a resistor R52, a resistor R58 and a capacitor C23; one end of the resistor R52 is used to be electrically connected to the negative electrode of the output end of the dimming output module, and the other end of the resistor R52 is electrically connected to the controller; The other end of the resistor R52 and one end of the resistor R58 are both electrically connected to one end of the capacitor C23 , and the other end of the resistor R58 and the other end of the capacitor C23 are both connected to the SGND ground terminal.

[0013] Furthermore, the second voltage division detection module and the first voltage division detection module have the same circuit structure.

[0014] Furthermore, the dimming output module is provided with an output common-mode inductor LF1, a first winding of the output common-mode inductor LF1 is connected in series to the positive output terminal of the dimming output module, and a second winding of the output common-mode inductor LF1 is connected in series to the negative output terminal of the dimming output module; The peripheral circuit of the dimming chip U1 includes a resistor R10, a resistor R12 and a resistor R16; the resistor R12 is connected in series to the input side of the second winding of the output common-mode inductor LF1, and the resistor R10 and the resistor R16 are both connected in parallel to the two ends of the resistor R12. One end of the resistor R12 electrically connected to the output common-mode inductor LF1 is connected to the current detection positive terminal of the dimming chip U1, and the other end of the resistor R12 is connected to the current detection negative terminal of the dimming chip U1.

[0015] The technical solution provided by the present invention can include the following beneficial effects: The dual dimming channels of dimming chip U1 are simultaneously utilized in the dimming output module. After the analog dimming signal (DIM) is adjusted from 100% to a minimum of 1%, the analog dimming signal remains unchanged at 1%, and the chopping dimming signal (PWM) is connected to further dim from 100% to 1%, thereby achieving a dimming scale of one ten-thousandth, and ultimately achieving expansion to lower load output voltages. Because the analog dimming signal suffers from unstable regulation and poor current accuracy when the output current is low, the analog dimming signal is primarily responsible for dimming at high brightness, while the chopping dimming signal is responsible for dimming at low brightness.

[0016] In addition, in order to cooperate with the load output voltage detection of the 1 / 10,000 dimming scale and ensure that the controller (such as MCU) can accurately adjust the analog dimming signal and the chopping dimming signal output to the dimming chip U1, an amplification detection module is provided for large load output voltage detection (because the detection point is at the negative pole of the output end of the dimming output module, the larger the load output voltage, the smaller the feedback, so signal amplification is required) and a first voltage divider detection module is provided for small load output voltage detection (based on the rule of the detection point, the small load feedback is large, and the voltage divider can be detected). On this basis, the controller will receive these two detection data at the same time, and decide which detection data the timing controller should select as the valid data based on the comparison between the detection data read from the first voltage divider detection module and the preset boundary value (for example, 10V); considering that the loaded output voltage will be relatively large most of the time (that is, for example, the proportion of above 10V is large), the detection data of the commonly used amplification detection module is used as the valid data, so the judgment right falls on the first voltage divider detection module for a better result. The detection data of the first voltage divider detection module is less than the preset boundary value for a long time. If it suddenly exceeds the preset boundary value, the controller can immediately sense and switch to using the detection data of the first voltage divider detection module as the valid data (the same applies to switching from the first voltage divider detection module to the amplification detection module); thereby ensuring the accuracy of the loaded output voltage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a driving power supply with fine dimming scale according to one embodiment of the present invention.

[0018] Figure 2 Yes Figure 1 The circuit diagram of the subtractor detection module is shown.

[0019] Figure 3 Yes Figure 1 The circuit diagram of the second voltage divider detection module and the ghost fire switch module is shown.

[0020] Figure 4 Yes Figure 1 The circuit diagram of the amplification detection module is shown.

[0021] Figure 5 Yes Figure 1 The circuit diagram of the first voltage division detection module is shown.

[0022] Among them: dimming output module 1, amplification detection module 2, first voltage divider detection module 3, subtractor detection module 5, second voltage divider detection module 6, ghost fire switch module 4, resistor R44, resistor R37, transistor Q4, transistor Q5, module shutdown unit 51, operational amplifier U4B, resistor R50, resistor R56, resistor R62, resistor R69, resistor R70, resistor R63, resistor R67, resistor R71, diode D11, resistor R49, resistor R46, transistor Q6, transistor Q7, operational amplifier U4A, resistor R65, resistor R66, resistor R51, resistor R53, resistor R57, resistor R52, resistor R58, capacitor C23, output common-mode inductor LF1, resistor R10, resistor R12, resistor R16. DETAILED DESCRIPTION

[0023] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0024] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically specified.

[0025] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal communication between two components or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0026] The following combination Figures 1 to 5 , describing a driving power supply with fine dimming scale according to an embodiment of the present invention.

[0027] A driver power supply with fine dimming scale includes a dimming output module 1 and a controller. The dimming output module 1 is integrated with a dimming chip U1 with dual dimming channels and its peripheral circuits, and also includes an amplification detection module 2 and a first voltage divider detection module 3. The controller is electrically connected to the dimming chip U1 and outputs an analog dimming signal and a chopping dimming signal to the dimming chip U1. When the analog dimming signal is adjusted to the lowest value, the chopping dimming signal intervenes for dimming. The negative electrode of the output end of the dimming output module 1 is electrically connected to the controller via the amplification detection module 2. The negative electrode of the output end of the dimming output module 1 is also electrically connected to the controller via the first voltage divider detection module 3. The amplification detection module 2 is used for large-load output voltage detection, and the first voltage divider detection module 3 is used for light-load output voltage detection. The controller reads the detection data from the first voltage divider detection module 3 and compares it with the preset boundary value; when the detection data is greater than the preset boundary value, the controller selects the data read from the first voltage divider detection module 3; when the detection data is less than or equal to the preset boundary value, the controller selects the data read from the amplification detection module 2.

[0028] The present invention proposes a preferred embodiment of a driving power supply with fine dimming scale, such as Figure 1 As shown, the dual dimming channels of the dimming chip U1 (for example, the DIM and PWM dimming pins of the Hi5010Q chip) are simultaneously utilized in the dimming output module 1. After the analog dimming signal (DIM) is adjusted from 100% to a minimum of 1%, the analog dimming signal remains unchanged at 1%, and the chopping dimming signal (PWM) is connected to further dim from 100% to 1%, thereby achieving a dimming scale of 1 / 10,000. The dimming current Iout can be obtained by Iout=Imax·D1·D2, where Imax is the maximum dimming current, D1 is the duty cycle of the analog dimming signal, and D2 is the duty cycle of the chopping dimming signal (D1 and D2 refer to the PWM signals sent by the controller to the dimming chip U1. The dimming chip U1 recognizes the PWM signals and then converts them into analog dimming signals and chopping dimming signals, respectively). Ultimately, when the output Vbus of the front-stage flyback module is 60V, the load output voltage range is 2.5V~49V (the range is for reference only), and it is expanded to a lower load output voltage. Among them, since the analog dimming signal has unstable adjustment and poor current accuracy when the output current is small, the analog dimming signal is mainly responsible for high-brightness dimming, and the chopping dimming signal is responsible for low-brightness dimming.

[0029] In addition, in order to cooperate with the load output voltage detection of the 1 / 10,000 dimming scale and ensure that the controller (such as MCU) can accurately adjust the analog dimming signal and the chopping dimming signal output to the dimming chip U1, an amplification detection module 2 is provided for large-load output voltage detection (because the detection point is at the negative pole of the output end of the dimming output module 1, the larger the load output voltage, the smaller the feedback, so signal amplification is required) and a first voltage divider detection module 3 is provided for small-load output voltage detection (based on the rule of the detection point, the small load feedback is large, and the voltage divider can be detected). On this basis, the controller will receive the two detection data at the same time, and decide which detection data the timing controller should select as the valid data based on the comparison between the detection data read from the first voltage divider detection module 3 and the preset boundary value (for example, 10V); considering that the loaded output voltage will be relatively large most of the time (that is, for example, the proportion of above 10V is large), the detection data of the commonly used amplification detection module 2 is used as the valid data, so the judgment right falls on the first voltage divider detection module 3 for a better result. The detection data of the first voltage divider detection module 3 is less than the preset boundary value for a long time. If it suddenly exceeds the preset boundary value, the controller can immediately sense and switch to using the detection data of the first voltage divider detection module 3 as the valid data (the same applies to switching from the first voltage divider detection module 3 to the amplification detection module 2); thereby ensuring the accuracy of the loaded output voltage detection.

[0030] Furthermore, it also includes a subtractor detection module 5 and a second voltage divider detection module 6; the negative output terminal of the dimming output module 1 is also electrically connected to the dimming chip U1 via the subtractor detection module 5, and the negative output terminal of the dimming output module 1 is also electrically connected to the controller via the second voltage divider detection module 6.

[0031] In this embodiment, the fault detection of the driving power supply is also affected during the process of changing the dimming scale. Therefore, the original fault detection circuit is modified and a subtractor detection module 5 and a second voltage divider detection module 6 are provided. The subtractor detection module 5 is mainly used to feedback the fault to the dimming chip U1, so that the dimming chip U1 can dynamically adjust the working state according to the detection data, shut down when a fault occurs, and automatically turn on after the fault disappears. It is suitable for faults with less impact (such as floating overvoltage). Therefore, it is necessary to use the subtractor function to convert its own reference voltage (such as Figure 2 VREF) and the detection point voltage (such as Figure 1 Medium LED- or Figure 2 The second voltage-dividing detection module 6 is mainly used to feed back faults to the controller to deal with faults with greater impact (such as severe overvoltage, short circuit, etc.). The voltage-dividing detection module provides detection data to the controller for comparison with the preset fault threshold (that is, it does not need to be very accurate, and the detection data may change significantly suddenly), and the controller implements global protection.

[0032] Furthermore, it also includes a ghost fire switch module 4; the negative electrode of the output end of the dimming output module 1 first passes through the ghost fire switch module 4, then passes through the amplification detection module 2, and is electrically connected to the controller; the negative electrode of the output end of the dimming output module 1 first passes through the ghost fire switch module 4, then passes through the first voltage divider detection module 3, and is electrically connected to the controller; The negative electrode of the output end of the dimming output module 1 first passes through the ghost fire switch module 4, then passes through the subtractor detection module 5, and is electrically connected to the dimming chip U1; the negative electrode of the output end of the dimming output module 1 first passes through the ghost fire switch module 4, then passes through the second voltage divider detection module 6, and is electrically connected to the controller; The ghost fire switch module 4 is electrically connected to the controller; the ghost fire switch module 4 is used to disconnect the circuit passing through the ghost fire switch module 4 under the control of the controller when the driving power supply is on standby.

[0033] In this embodiment, the driving power supply integrates multiple detection branches such as the amplification detection module 2, the first voltage divider detection module 3, the subtractor detection module 5 and the second voltage divider detection module 6, and the detection points are all located at the negative pole of the output end of the dimming output module 1. When the driving power supply is dimmed to the lowest standby state, these branches are very easy to provide a discharge circuit for the electrolytic capacitor CE1 of the dimming output module 1 (especially the voltage divider detection branch, with a voltage divider resistor used as a discharge resistor), and leakage current flows from the output end of the dimming output module 1 to the connected load lamp (such as LED lamps, which have parasitic capacitance), causing the parasitic capacitance of the load to be divided, and the load lamp is re-lit, resulting in a ghost fire phenomenon; for this reason, a ghost fire switch module 4 is provided, so that these detection branches must all pass through the ghost fire switch module 4, so that when the driving power supply is on standby, the ghost fire switch module 4 is used to cut off all detection branches at the same time, effectively solving the ghost fire problem.

[0034] Furthermore, the ghost fire switch module 4 includes a resistor R44, a resistor R37, a transistor Q4 and a transistor Q5; one end of the resistor R44 is electrically connected to the controller, the other end of the resistor R44 is electrically connected to the base of the transistor Q5, the emitter of the transistor Q5 is connected to the SGND ground terminal, the collector of the transistor Q5 is electrically connected to the base of the transistor Q4 via the resistor R37, the emitter of the transistor Q4 is electrically connected to the negative output terminal of the dimming output module 1, and the amplification detection module 2, the first voltage divider detection module 3, the subtractor detection module 5, and the second voltage divider detection module 6 are all electrically connected to the collector of the transistor Q4.

[0035] In this embodiment, Figure 3 As shown, the ghost fire switch module 4 is preferably composed of dual triodes, wherein the triode Q4 is used to cut off the circuit and the triode Q5 is used to accelerate the drive. The specific principle is as follows: (1) When the driving power supply is in normal working state, the CHECK-EN2 signal is controlled by the controller to be high level.

[0036] For NPN transistor Q5, the base voltage Vb>Ve and the collector voltage Vc>Vb, so Q5 is in the on state and current flows from the collector to the emitter. At this time, for PNP transistor Q4, the base is pulled down to ground through resistor R37, the emitter voltage Ve>Vb, and the base voltage Vb>Vc, so Q4 is also in the on state.

[0037] Therefore, when the driving power supply is in a normal working state, the transistor Q4 and the transistor Q5 are both normally turned on, and all detection branches can operate normally.

[0038] (2) When the drive power supply is in standby state, the CHECK-EN2 signal is controlled by the controller to be low level.

[0039] For transistor Q5, the base voltage Vb≈Ve, and transistor Q5 is not conducting; for transistor Q4, the base is equivalent to being suspended, and the emitter Ve≈Vb, so transistor Q4 is also not conducting.

[0040] Therefore, when the driving power supply is in standby mode, transistor Q4 and transistor Q5 work together to cut off the discharge circuit, and no leakage current will flow through the load lamp, effectively solving the ghost fire problem.

[0041] Furthermore, the subtractor detection module 5 includes a module shutdown unit 51, an operational amplifier U4B, a resistor R50, a resistor R56, a resistor R62, a resistor R69, a resistor R70, a resistor R63, a resistor R67, a resistor R71 and a diode D11; one end of the resistor R63 is electrically connected to the negative electrode of the output terminal of the dimming output module 1, the other end of the resistor R63 is electrically connected to one end of the resistor R67, the other end of the resistor R67 and one end of the resistor R71 are both electrically connected to one end of the resistor R70, the other end of the resistor R71 is connected to the SGND ground terminal, the other end of the resistor R70 and one end of the resistor R69 are both electrically connected to the negative input terminal of the operational amplifier U4B, the other end of the resistor R69 and the anode of the diode D11 are both electrically connected to the output terminal of the operational amplifier U4B, and the cathode of the diode D11 is electrically connected to the dimming chip U1; The power supply voltage is electrically connected to one end of the resistor R50 via the module shutdown unit 51, and the other end of the resistor R50 is electrically connected to one end of the resistor R56; the other end of the resistor R56 and one end of the resistor R62 are both electrically connected to the positive input terminal of the operational amplifier U4B, and the other end of the resistor R62 is connected to the SGND ground terminal; The module closing unit 51 is electrically connected to the controller; the module closing unit 51 is used to disconnect the circuit passing through the module closing unit 51 under the control of the controller when the driving power supply is on standby.

[0042] In this embodiment, according to the specifications of the general dimming chip U1, it can be used as a buck topology or a boost topology. The VFB pin of the dimming chip U1 is often used for overvoltage protection. Taking the dimming chip U1 as the Hi5010Q chip as an example, when the VFB voltage is higher than 1.2V, the chip shuts down the output, and when the VFB voltage is lower than 1.1V, the chip restarts the output. Based on this, the circuit structure of the subtractor detection module 5 is designed as follows Figure 2 As shown, the specific working principle is as follows ( Figure 2 The VREF and VLED- labels in the dotted box are only used as reference points in the calculation process and do not represent the connection relationship): Using op amp U4B as a subtractor, the voltage of LED- (VLED-) serves as the inverting input of the subtractor. This gives a reference voltage of VLED1- = (LED-·R71) / (R63+R67+R71), where LED- represents the corresponding voltage and R71, R63, R67, and R71 represent the corresponding resistance values. Given a reference voltage VREF at the non-inverting input, VREF = [power supply voltage·(R56+R62)] / (R50+R56+R62), where R50, R56, and R62 represent the corresponding resistance values.

[0043] Setting R69=R62 and R70=R56, we can get: VFB=VREF-(VLED1-)·R69 / R70; where R69 and R70 are the corresponding resistance values.

[0044] It can be seen from the calculation formula of VFB that VREF is a fixed value, while VLED1- decreases as the loaded output voltage Vout increases. Therefore, VFB will increase as Vout increases (accurate dynamic detection data). By reasonably allocating the resistance values ​​of the subtractor resistors R69 and R70, VFB reaches 1.2V when Vout approaches 60V (i.e., triggering the overvoltage protection of the dimming chip U1), thereby triggering the overvoltage protection of the dimming chip U1, so that Vout is limited to below 60V, thus achieving overvoltage protection.

[0045] In summary, by reasonably allocating the power supply voltage, resistor R69, and resistor R70, the subtractor detection module 5 can adapt to different upper limits of the loaded output voltage range (solving the problem of being unable to detect and perform overvoltage protection after the loaded output voltage range is expanded) and adapt to the trigger thresholds of different dimming chips U1.

[0046] Based on the circuit structure of the subtractor detection module 5 and the ghost fire switch module 4, when the driving power supply is in standby mode, the ghost fire switch module 4 cuts off the circuit. At this time, VLED- is always 0. This state is the same as no-load. When no-load, VLED- is 0. Since the overvoltage protection of the dimming chip U1 will inevitably be triggered when no-load, it means that the overvoltage protection of the dimming chip U1 will also be triggered in the standby state, which is a false protection. In order to prevent the overvoltage protection from being triggered in the standby state, a module shutdown unit 5 is set to cut off VREF in the standby state. Then the non-inverting input of the operational amplifier U4B is 0, and the inverting input is also 0. Then VFB is also 0 according to the formula, and the overvoltage protection will not be triggered.

[0047] Furthermore, the module shutdown unit 51 includes a resistor R49, a resistor R46, a transistor Q6 and a transistor Q7; one end of the resistor R49 is electrically connected to the controller, the other end of the resistor R49 is electrically connected to the base of the transistor Q7, the emitter of the transistor Q7 is connected to the SGND ground terminal, the collector of the transistor Q7 is electrically connected to the base of the transistor Q6 via the resistor R46, the emitter of the transistor Q6 is connected to the power supply voltage, and the collector of the transistor Q6 is electrically connected to one end of the resistor R50.

[0048] In this embodiment, the module shutdown unit 51 and the ghost fire switch module 4 are similar, wherein the transistor Q6 is used to cut off the loop, and the transistor Q7 is used to accelerate the drive. The controller sends a low-level CHECK-EN1 signal in the standby state to drive the transistors Q6 and Q7 to cut off VREF, then the positive input of the operational amplifier U4B is 0, and the negative input is also 0, then VFB is also 0 according to the formula, and the overvoltage protection will not be triggered.

[0049] It should be noted that there are multiple ways to configure the CHECK-EN1 signal and the CHECK-EN2 signal. They can be two different signals, or the same signal (because both are cut off in the standby state).

[0050] Furthermore, the amplification and detection module 2 includes an operational amplifier U4A, a resistor R65, a resistor R66, a resistor R51, a resistor R53, and a resistor R57; one end of the resistor R51 is used to be electrically connected to the negative electrode of the output terminal of the dimming output module 1, the other end of the resistor R51 is electrically connected to one end of the resistor R53, the other end of the resistor R53 and one end of the resistor R57 are both electrically connected to the positive input terminal of the operational amplifier U4A, and the other end of the resistor R57 is connected to the SGND ground terminal; The output end of the operational amplifier U4A is electrically connected to the controller, the output end of the operational amplifier U4A is electrically connected to one end of the resistor R65, the other end of the resistor R65 and one end of the resistor R66 are both electrically connected to the negative input end of the operational amplifier U4A, and the other end of the resistor R66 is connected to the SGND ground end.

[0051] In this embodiment, Figure 4 As shown, the amplification detection module 2 is mainly composed of an operational amplifier U4A and its peripheral circuits to form a differential amplifier. After the controller reads the output of the differential amplifier, it performs a reverse operation to obtain the loaded output voltage, thereby ensuring the accuracy of detection under heavy load.

[0052] Furthermore, the first voltage division detection module 3 includes a resistor R52, a resistor R58 and a capacitor C23; one end of the resistor R52 is used to be electrically connected to the negative electrode of the output end of the dimming output module 1, and the other end of the resistor R52 is electrically connected to the controller; The other end of the resistor R52 and one end of the resistor R58 are electrically connected to one end of the capacitor C23 , and the other end of the resistor R58 and the other end of the capacitor C23 are connected to the SGND ground terminal.

[0053] Furthermore, the circuit structure of the second voltage division detection module 6 is the same as that of the first voltage division detection module 3 .

[0054] In this embodiment, Figure 3 and Figure 5 As shown, both the first voltage-dividing detection module 3 and the second voltage-dividing detection module 6 preferably use resistors to form a voltage-dividing circuit. Taking the second voltage-dividing detection module 6 as an example, the second voltage-dividing detection module 6 is primarily designed to detect short-circuit faults. For example, when a short circuit occurs at the output, it is equivalent to shorting LED+ and LED- together, meaning that the voltages of Vbus, LED+, and LED- are equal. At this point, the voltage of LED- far exceeds the normal operating state, causing the controller to immediately recognize this and initiate an emergency brake function, providing timely short-circuit protection to prevent damage to the device caused by a prolonged short circuit.

[0055] Furthermore, the dimming output module 1 is provided with an output common-mode inductor LF1, a first winding of the output common-mode inductor LF1 is connected in series to the positive output terminal of the dimming output module 1, and a second winding of the output common-mode inductor LF1 is connected in series to the negative output terminal of the dimming output module 1; The peripheral circuit of the dimming chip U1 includes resistors R10, R12 and R16; resistor R12 is connected in series to the input side of the second winding of the output common-mode inductor LF1, and resistors R10 and R16 are both connected in parallel to the two ends of resistor R12. One end of resistor R12 electrically connected to the output common-mode inductor LF1 is connected to the positive current detection terminal of the dimming chip U1, and the other end of resistor R12 is connected to the negative current detection terminal of the dimming chip U1.

[0056] In this embodiment, because the dimming scale decreases, the dimming range increases, and the load range also increases accordingly, the dimming chip U1 is prone to poor load regulation. Therefore, resistors R10, R12, and R16 (sampling resistors) are placed on the input side of the output common-mode inductor LF. The voltage across the sampling resistors is then detected using the positive current sensing terminal (isenP) and negative current sensing terminal (isenN) of the dimming chip U1 (current is converted into voltage for easy chip identification). This allows the buck dimming output module to detect the current output current (commonly referred to as the full detection cycle) regardless of whether the MOS transistor Q2 is in the on phase (also known as the Ton phase) or the off phase (also known as the Toff freewheeling phase). The Ton time is then adjusted in real time based on the output current. This effectively improves the problem of poor regulation, as the output current is less affected by the load.

[0057] Other structures and operations of a driving power supply with fine dimming scale according to an embodiment of the present invention are known to those skilled in the art and will not be described in detail here.

[0058] Throughout this specification, reference to terms such as "embodiment" or "example" indicates that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A driving power supply with fine dimming scale, comprising a dimming output module and a controller; characterized in that: The dimming output module is integrated with a dimming chip U1 having dual dimming channels and its peripheral circuits, and also includes an amplification detection module and a first voltage division detection module. The controller is electrically connected to the dimming chip U1 and outputs an analog dimming signal and a chopping dimming signal to the dimming chip U1. When the analog dimming signal is adjusted to the lowest value, the chopping dimming signal intervenes in the dimming. The negative electrode of the output end of the dimming output module is electrically connected to the controller via the amplification detection module, and the negative electrode of the output end of the dimming output module is also electrically connected to the controller via the first voltage divider detection module; the amplification detection module is used for large-load output voltage detection, and the first voltage divider detection module is used for light-load output voltage detection; The controller reads detection data from the first voltage divider detection module and compares it with a preset threshold value; when the detection data is greater than the preset threshold value, the controller selects the data read from the first voltage divider detection module; when the detection data is less than or equal to the preset threshold value, the controller selects the data read from the amplification detection module.

2. The driving power supply with fine dimming scale according to claim 1, characterized in that: It also includes a subtractor detection module and a second voltage divider detection module; the negative output terminal of the dimming output module is also electrically connected to the dimming chip U1 via the subtractor detection module, and the negative output terminal of the dimming output module is also electrically connected to the controller via the second voltage divider detection module.

3. The driving power supply with fine dimming scale according to claim 2, characterized in that: It also includes a ghost fire switch module; the negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the amplification detection module, and is electrically connected to the controller; the negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the first voltage divider detection module, and is electrically connected to the controller; The negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the subtractor detection module, and is electrically connected to the dimming chip U1; the negative electrode of the output end of the dimming output module first passes through the ghost fire switch module, then passes through the second voltage divider detection module, and is electrically connected to the controller; The ghost fire switch module is electrically connected to the controller; the ghost fire switch module is used to disconnect the circuit passing through the ghost fire switch module under the control of the controller when the driving power supply is on standby.

4. The driving power supply with fine dimming scale according to claim 3, characterized in that: The ghost fire switch module includes a resistor R44, a resistor R37, a transistor Q4 and a transistor Q5; one end of the resistor R44 is electrically connected to the controller, the other end of the resistor R44 is electrically connected to the base of the transistor Q5, the emitter of the transistor Q5 is connected to the SGND ground terminal, the collector of the transistor Q5 is electrically connected to the base of the transistor Q4 via the resistor R37, the emitter of the transistor Q4 is electrically connected to the negative output terminal of the dimming output module, and the amplification detection module, the first voltage divider detection module, the subtractor detection module, and the second voltage divider detection module are all electrically connected to the collector of the transistor Q4.

5. The driving power supply with fine dimming scale according to claim 3, characterized in that: The subtractor detection module includes a module shutdown unit, an operational amplifier U4B, a resistor R50, a resistor R56, a resistor R62, a resistor R69, a resistor R70, a resistor R63, a resistor R67, a resistor R71 and a diode D11; one end of the resistor R63 is electrically connected to the negative electrode of the output end of the dimming output module, the other end of the resistor R63 is electrically connected to one end of the resistor R67, the other end of the resistor R67 and one end of the resistor R71 are both electrically connected to one end of the resistor R70, the other end of the resistor R71 is connected to the SGND ground terminal, the other end of the resistor R70 and one end of the resistor R69 are both electrically connected to the negative input terminal of the operational amplifier U4B, the other end of the resistor R69 and the anode of the diode D11 are both electrically connected to the output end of the operational amplifier U4B, and the cathode of the diode D11 is electrically connected to the dimming chip U1; The power supply voltage is electrically connected to one end of the resistor R50 via the module shutdown unit, and the other end of the resistor R50 is electrically connected to one end of the resistor R56; the other end of the resistor R56 and one end of the resistor R62 are both electrically connected to the positive input terminal of the operational amplifier U4B, and the other end of the resistor R62 is connected to the SGND ground terminal; The module closing unit is electrically connected to the controller; the module closing unit is used to disconnect the circuit passing through the module closing unit under the control of the controller when the driving power supply is on standby.

6. The driving power supply with fine dimming scale according to claim 5, characterized in that: The module shutdown unit includes a resistor R49, a resistor R46, a transistor Q6 and a transistor Q7; one end of the resistor R49 is electrically connected to the controller, the other end of the resistor R49 is electrically connected to the base of the transistor Q7, the emitter of the transistor Q7 is connected to the SGND ground terminal, the collector of the transistor Q7 is electrically connected to the base of the transistor Q6 via the resistor R46, the emitter of the transistor Q6 is connected to the power supply voltage, and the collector of the transistor Q6 is electrically connected to one end of the resistor R50.

7. The driving power supply with fine dimming scale according to claim 1, characterized in that: The amplification and detection module includes an operational amplifier U4A, a resistor R65, a resistor R66, a resistor R51, a resistor R53, and a resistor R57; one end of the resistor R51 is used to be electrically connected to the negative electrode of the output terminal of the dimming output module, the other end of the resistor R51 is electrically connected to one end of the resistor R53, the other end of the resistor R53 and one end of the resistor R57 are both electrically connected to the positive input terminal of the operational amplifier U4A, and the other end of the resistor R57 is connected to the SGND ground terminal; The output end of the operational amplifier U4A is electrically connected to the controller, the output end of the operational amplifier U4A is electrically connected to one end of the resistor R65, the other end of the resistor R65 and one end of the resistor R66 are both electrically connected to the negative input end of the operational amplifier U4A, and the other end of the resistor R66 is connected to the SGND ground end.

8. The driving power supply with fine dimming scale according to claim 1, characterized in that: The first voltage division detection module includes a resistor R52, a resistor R58 and a capacitor C23; one end of the resistor R52 is used to be electrically connected to the negative electrode of the output end of the dimming output module, and the other end of the resistor R52 is electrically connected to the controller; The other end of the resistor R52 and one end of the resistor R58 are both electrically connected to one end of the capacitor C23 , and the other end of the resistor R58 and the other end of the capacitor C23 are both connected to the SGND ground terminal.

9. The driving power supply with fine dimming scale according to claim 2, characterized in that: The second voltage division detection module and the first voltage division detection module have the same circuit structure.

10. The driving power supply with fine dimming scale according to claim 1, characterized in that: The dimming output module is provided with an output common-mode inductor LF1, a first winding of the output common-mode inductor LF1 is connected in series to the positive output terminal of the dimming output module, and a second winding of the output common-mode inductor LF1 is connected in series to the negative output terminal of the dimming output module; The peripheral circuit of the dimming chip U1 includes a resistor R10, a resistor R12 and a resistor R16; the resistor R12 is connected in series to the input side of the second winding of the output common-mode inductor LF1, and the resistor R10 and the resistor R16 are both connected in parallel to the two ends of the resistor R12. One end of the resistor R12 electrically connected to the output common-mode inductor LF1 is connected to the current detection positive terminal of the dimming chip U1, and the other end of the resistor R12 is connected to the current detection negative terminal of the dimming chip U1.

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