Circuit for sharing power of chip by serially connecting resistor and LED (light-emitting diode)

Abstract

The utility model belongs to the technical field of automobile lamp driving circuits, and particularly relates to a circuit for sharing chip power by connecting resistors and LEDs in series, which comprises a power supply module, a communication module, a driving module, an LED load and a resistive load, the power supply module and the communication module are both connected with the driving module, and the power supply module supplies power to the driving module. The communication module transmits a control signal to the driving module, one end of the LED load is connected with the driving module, the driving module drives the LED load, the other end of the LED load is connected to the driving module through the series resistance load, and the power of the driving module is shared through the series resistance load. According to the circuit for sharing the chip power by connecting the resistors and the LEDs in series, on the premise that the number of the chips is not increased and the PCB material and the heat dissipation scheme are not changed, the channel utilization rate of the multi-channel chips is improved, and the purposes of reducing the cost, reducing the bus load rate, reducing the risk of electromagnetic compatibility and reducing the development difficulty of tools and jigs are achieved. The circuit complexity is reduced; and the reliability is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of automobile lamp driving circuits, and particularly relates to a circuit that uses a resistor and an LED in series to share chip power. Background Art

[0002] LEDs are becoming increasingly common in automotive lighting. To achieve diverse styling and striking effects, the number of LEDs used in lamps is also increasing. Initial light guide solutions used only 1-3 LEDs, while reflective solutions employed around 10 LEDs per row. Furthermore, taillights now feature hundreds of LEDs throughout the entire strip. The latest products now employ thousands of LEDs, creating display-like effects. Consequently, the requirements for circuit driving capabilities are becoming increasingly stringent. Currently, the industry often uses multi-channel driver chips to control hundreds of LEDs.

[0003] Mainstream multi-channel chips include Infineon's 16-channel TLD7002, ELMOS's 16-channel E522.94, and Texas Instruments' 12-channel TPS929120. All of these chips have more than 10 channels, and each channel's current drive capability is generally 75-100mA. A chip can withstand about 1W of power on a double-sided FR4 circuit board. Considering that the chip's operating voltage drop is generally above 1V, if you want to use all of the chip's 12 output channels, the ideal single-channel current can reach 80mA, essentially fully utilizing the advantages of multi-channel chips.

[0004] Because LEDs are divided into voltage bins (i.e., voltage differences exist between LED production batches), for example, the voltage range of red LEDs in different bins is approximately 1.9-2.5V. Taking a string of three LEDs as an example, the voltage difference caused by the different LED voltage bins on the chip can reach 1.8V. This voltage difference is usually borne by the chip in the design. This means that the design voltage on the chip needs to take into account the 1V of the highest voltage bin and the 1.8V voltage difference caused by the voltage bins, for a total of 2.8V. This is far greater than the normal voltage value required by the chip. Since the power that the chip can handle is fixed, the actual current we can use is only 35% of the ideal current. This is equivalent to only being able to use a maximum of 5 channels of a 12-channel chip at the same 80mA.

[0005] It is obvious that current application solutions do not fully utilize the advantages of multi-channel chips. Only when the current of a single channel is less than 30mA can all 12 channels be fully utilized. In applications with slightly higher current and a large number of LEDs, some channels need to be abandoned and the number of chips needs to be increased to achieve the desired effect, which increases the cost of parts. In addition, the increase in the number of chips will increase the bus load rate, affecting the software communication rate and effect. Too many chips across multiple PCB boards also pose EMC risks and poor electromagnetic compatibility. Multi-channel chips also involve configuration program burning, and the increase in the number of chips will also make tooling more difficult and increase costs. The more chips are used, the more complex the circuit is, and the corresponding reliability will also be reduced.

[0006] If increasing the number of chips is undesirable, another option is to use a solution with better heat dissipation, such as a four-layer board, a double-sided aluminum substrate, or adding a heat sink. However, this solution will significantly increase costs, so it is not chosen by engineers. Other optimization measures include reducing the LED current, but this will affect the brightness, which will in turn affect product uniformity and even regulatory compliance, and will not meet customer requirements. Reducing or even selecting a small number of LED voltage bins is theoretically feasible. Since there are 4-5 LED voltage bins per version, even if it is reduced to 2, there is still a 0.9V voltage difference, which can appropriately improve chip channel utilization. However, it involves the production capacity distribution of LED suppliers. Limiting the supply of voltage bins will lead to increased LED costs and carry a huge risk of material shortages and line stoppages. In practice, LED suppliers will not agree to this, especially for high-volume projects. Utility Model Content

[0007] In order to solve the above technical problems, the utility model provides a circuit that uses a resistor and an LED in series to share the chip power. Without increasing the number of chips and without changing the PCB material and heat dissipation solution, the channel utilization rate of the multi-channel chip is improved, thereby achieving the beneficial effects of reducing costs, reducing bus load rate, reducing electromagnetic compatibility risks, reducing the difficulty and cost of tooling and fixture development, reducing circuit complexity and improving reliability.

[0008] The utility model provides a circuit that uses a resistor and an LED in series to share chip power, including:

[0009] A power supply module, a communication module, a drive module, an LED load, and a resistive load. The power supply module and the communication module are both connected to the drive module. The power supply module supplies power to the drive module. The communication module transmits a control signal to the drive module. One end of the LED load is connected to the drive module, and the drive module drives the LED load. The other end of the LED load is connected to the drive module via the resistive load in series, and the power of the drive module is shared by the resistive load in series.

[0010] A load circuit is added to share the voltage applied to the driver chip by the LED voltage BIN. This load circuit adjusts parameters based on the LED voltage BIN, ensuring a low voltage across the resistor load when the LED voltage is high and a high voltage across the resistor load when the LED voltage is low. This ensures that the voltage across the driver chip remains stable, sufficient for operation without overcharging the chip. Because the load circuit regulates the voltage in conjunction with the LEDs, it must be connected in series with the LEDs. This requires connecting the load to every active channel of the chip, which requires a low-cost load circuit. Therefore, resistors are the preferred choice.

[0011] Furthermore, the driving module adopts a multi-channel driving chip, the LED load is multi-channel, the resistance load is multi-channel, and the multi-channel LED load corresponds to the multi-channel resistance load in a one-to-one manner.

[0012] Optionally, the driving module is a high-side driving chip, the positive pole of the LED load is connected to the driving module, the negative pole of the LED load is connected to one end of the resistive load, and the other end of the resistive load is grounded with the driving module.

[0013] Optionally, the driving module is a low-side driving chip, the power supply module and the driving module are both connected to the positive pole of the LED load, the negative pole of the LED load is connected to one end of the resistive load, and the other end of the resistive load receives the control signal of the driving module.

[0014] Furthermore, any LED load is 1-4 LEDs connected in series.

[0015] Furthermore, the high-side driver chip is TPS929120, which has 12 output channels.

[0016] Furthermore, the low-side driver chip is TLD7002, which has 16 output channels.

[0017] The beneficial effects of the utility model are:

[0018] The utility model uses a circuit that uses a resistor and an LED in series to share chip power. Without increasing the number of chips and without changing the PCB material and heat dissipation solution, it improves the channel utilization of multi-channel chips, thereby achieving the beneficial effects of reducing costs, reducing bus load rate, reducing electromagnetic compatibility risks, reducing the difficulty and cost of tooling and fixture development, reducing circuit complexity, and improving reliability.

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a module diagram of a circuit for high-side driving that uses a resistor and an LED in series to share chip power.

[0022] Figure 2 This is a module diagram of a circuit for low-side driving that uses a resistor and an LED in series to share chip power.

[0023] Figure 3 This is a core circuit schematic diagram of the high-side driver of the utility model, which uses a resistor and an LED in series to share chip power.

[0024] Figure 4 This is the core circuit principle diagram of the low-side driver of the utility model, which uses a resistor and an LED in series to share the chip power;

[0025] Figure 5 This is a common resistor connection principle diagram of the core resistor load of the present invention.

[0026] In the picture:

[0027] 1. Power module; 2. Communication module; 3. Multi-channel driver chip; 4. LED load; 5. Resistor load. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0029] like Figures 1 to 5 As shown, the utility model provides a circuit for sharing chip power by connecting a resistor in series with an LED, comprising:

[0030] A power supply module 1, a communication module 2, a drive module, an LED load 4, and a resistance load 5. The power supply module 1 and the communication module 2 are both connected to the drive module. The power supply module 1 supplies power to the drive module. The communication module 2 transmits a control signal to the drive module. One end of the LED load 4 is connected to the drive module. The drive module drives the LED load 4. The other end of the LED load 4 is connected to the drive module through the series resistance load 5, and the power of the drive module is shared through the series resistance load 5.

[0031] The driving module adopts a multi-channel driving chip 3, the LED load 4 is multi-channel, the resistance load 5 is multi-channel, and the multi-channel LED load 4 corresponds to the multi-channel resistance load 5 in a one-to-one manner.

[0032] Multi-channel driver chips come in two types: high-side and low-side. High-side drivers connect the chip's output channels to the LED's positive terminal, with the LED's negative terminal connected to ground. Low-side drivers connect the chip's output channels to the LED's negative terminal, with the LED's positive terminal connected to a power source. The load circuits of this utility model are applicable to both types of driver chips, and are described below with reference to the accompanying figures.

[0033] like Figure 1 The circuit framework of the high-side chip, the circuit architecture is composed of multiple modules, and the connection and application of the resistance load 5 is the core of the present invention. The explanation is centered around the multi-channel driver chip 3: the power module 1 provides power to the multi-channel driver chip 3; the communication module 2 communicates with the multi-channel driver chip 3 according to the communication method supported by the corresponding driver chip (such as CAN / LIN / UART / SPI / I2C, etc.). The communication module 2 can be the MCU in the product, or it can be an independent controller, or even a superior product domain controller, etc. The communication signal can transmit lighting commands, adjust LED brightness, control LED lighting timing, read various fault information, etc.; the multi-channel driver chip 3 is connected to the LED load 4 through the high-side control signal, that is, the output PIN pins of the multi-channel driver chip 3 are respectively connected to the positive pole of the first LED in the LED string; the LED load 4 consists of 1 to multiple LEDs. If you want to do For open-circuit and short-circuit diagnosis of LEDs, LED load 4 is a string of LEDs. If no diagnosis is performed, it can also be a group of LEDs in a mesh structure. Taking the application of more single-string LEDs as an example, LED load 4 usually consists of 1 to 4 LEDs connected in series. If the supply voltage provided by power module 1 is high enough, LED load 4 can also have more LEDs connected in series. The cathode of the last LED in LED load 4 is connected to resistor load 5. Resistor load 5 is usually composed of 1 to multiple resistors. These resistors can be all connected in parallel, all in series, or a combination of series and parallel. We regard these resistors as a whole equivalent resistance, and this equivalent resistance is in series with LED load 4. In high-side driver chip applications, the other end of resistor load 5 is directly grounded and shares the same ground with multi-channel driver chip 3 to form a complete loop.

[0034] like Figure 2 The circuit framework of the low-side chip is similar to that of the high-side chip. The five modules differ only in the high and low sides of the multi-channel driver chip 3, and the rest of the modules are the same. The main connections and differences are explained in detail: the power module 1 provides power to the multi-channel driver chip 3 and the LED load 4, and is connected to the positive pole of the LED light string in the LED load 4. The communication module 2 communicates with the multi-channel driver chip 3. The negative pole of the last LED in the LED load 4 is connected to the resistive load 5. We regard all the resistors in the resistive load 5 as an equivalent resistance as a whole. Then, the equivalent resistance is in series with the LED load 4. The multi-channel driver chip 3 is connected to the resistive load 5 through the low-side control signal, that is, the output PIN pin of the multi-channel driver chip 3 is connected to the other end of each resistive load 5, and the grounding is controlled by the low-side switch inside the chip to form a complete loop.

[0035] like Figure 3 As shown in the figure, the core circuit schematic for a 12-channel high-side driver chip (TI TPS929120) with two LEDs (OSRAM LY G6SP) in a string is used as an example. The power supply is connected to the front-end power module. The supply voltage must be set to ensure that the voltage drop across the chip at the highest LED voltage bin is greater than the 1V required for normal operation. In this application, it is set to 6V. It is connected to the front-end communication module (MCU) via UART (TX / RX). Two channels are combined and the 12 output channels (OUT0 to OUT11) are connected to six LED strings. Each LED string consists of two LEDs connected in series, and each LED string is then connected to a load resistor. As shown in Table 1, the LY G6SP has four voltage bins. The voltage values of the different bins are used to calculate the total LED string voltage. The current per LED is calculated as 160mA.

[0036] In this load solution, after subtracting the total LED string voltage from the supply voltage, the remaining voltage falls on the multi-channel driver chip 3 and the resistive load 5 respectively. By matching different resistive load values to different LED voltage BINs, the resistor receives more power at the low-voltage BIN, less power at the high-voltage BIN, and no additional power at the highest voltage BIN. At this time, the voltage drop on the chip can be seen to be stable at 1V, which is sufficient for the chip to operate. The power of a single chip is 1W, which can meet the thermal requirements in conventional PCB board applications.

[0037] Similarly, the current traditional solution is calculated and compared with the effect of the present invention. It can be seen that when there is no resistive load 5, the remaining voltage after subtracting the total voltage of the LED string from the supply voltage falls entirely on the chip. When the highest voltage BIN is reached, the voltage on the chip is just enough for the chip to work, so the input voltage cannot be reduced. When the minimum voltage BIN is reached, the voltage on the chip reaches 1.9V, and the corresponding maximum power of the chip reaches 1.8W. Therefore, the current traditional solution needs to use two chips to meet the heat dissipation requirements.

[0038] Table 1:

[0039]

[0040] like Figure 4 As shown in the figure, the core circuit schematic for a 16-channel low-side driver chip (INF TLD7002) with a string of three LEDs (OSRAM LA E67F) is used as an example. The power supply is connected to front-end power module 1. The supply voltage is set to ensure that the voltage drop across the chip at the highest LED voltage bin is greater than the 1V required for normal operation. In this application, it is set to 8.5V. It is connected to front-end communication module 2 (MCU) via CAN communication. The 16 output channels OUT0 to OUT15 are connected to 16 LED strings. Each LED string consists of three LEDs connected in series, and each LED string is then connected to a load resistor. As shown in Table 2, the LAE67F has five voltage bins. The voltage values of each bin are used to calculate the total LED string voltage. The current per LED is calculated as 60mA.

[0041] In this load solution, after subtracting the total LED string voltage from the supply voltage, the remaining voltage falls on the chip and the resistive load respectively. By matching different resistor load values to different LED voltage BINs, the resistor receives more power at the low-voltage BIN, less power at the high-voltage BIN, and no additional power at the highest voltage BIN. At this point, the voltage drop on the chip is stable at 1V, sufficient for chip operation, and the power of a single chip is 1W. In other words, in conventional PCB board applications, a single driver chip can meet the thermal requirements.

[0042] Similarly, the current traditional solution is calculated and compared with the effect of the present invention. It can be seen that when there is no resistive load 5, the remaining voltage after subtracting the total voltage of the LED string from the supply voltage falls entirely on the chip. When the highest voltage BIN is reached, the voltage on the chip is just enough for the chip to work, so the input voltage cannot be reduced. When the minimum voltage BIN is reached, the voltage on the chip reaches 2.8V, and the corresponding maximum power of the chip reaches 2.7W. Therefore, the current traditional solution needs to use three chips to meet the heat dissipation requirements.

[0043] Table 2:

[0044]

[0045] The resistor load mentioned above can actually use one or more resistors, and the selection is mainly based on the power of the resistor, such as Figure 4 Application, the maximum power of a single-channel equivalent resistor is 0.13W. Considering the high and low temperature environment, you can use a 1206 package resistor, or two 0805 package resistors in parallel or series, or four 0603 package resistors in series and parallel. The typical schematic diagram is as follows Figure 5 shown.

[0046] In summary, the circuit of the utility model uses a resistor and an LED in series to share chip power. Without increasing the number of chips and without changing the PCB material and heat dissipation solution, it improves the channel utilization of multi-channel chips, thereby achieving the beneficial effects of reducing costs, reducing bus load rate, reducing electromagnetic compatibility risks, reducing the difficulty and cost of tooling and fixture development, reducing circuit complexity and improving reliability.

[0047] The various devices selected in this application are all universal standard parts or components known to those skilled in the art, and their structures and principles can be known to those skilled in the art through technical manuals or conventional experimental methods.

[0048] In the description of the embodiments of the present invention, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0049] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] Based on the above-mentioned ideal embodiment of the present invention, and in accordance with the above description, relevant personnel can make various changes and modifications without departing from the technical scope of the present invention. The technical scope of the present invention is not limited to the content of the specification, but must be determined according to the scope of the claims.

Claims

1. A circuit that uses a resistor in series with an LED to share chip power, characterized in that: include: A power module (1), a communication module (2), a drive module, an LED load (4), and a resistance load (5), wherein the power module (1) and the communication module (2) are both connected to the drive module, the power module (1) supplies power to the drive module, the communication module (2) transmits a control signal to the drive module, one end of the LED load (4) is connected to the drive module, the drive module drives the LED load (4), and the other end of the LED load (4) is connected to the drive module via the resistance load (5) in series, so that the power of the drive module is shared by the resistance load (5) in series.

2. The circuit for sharing chip power by connecting a resistor in series with an LED according to claim 1, wherein: The driving module adopts a multi-channel driving chip (3), the LED load (4) is multi-channel, the resistance load (5) is multi-channel, and the multi-channel LED load (4) corresponds to the multi-channel resistance load (5) in a one-to-one manner.

3. The circuit for sharing chip power by connecting a resistor in series with an LED according to claim 1, wherein: The driving module is a high-side driving chip, the positive electrode of the LED load (4) is connected to the driving module, the negative electrode of the LED load (4) is connected to one end of the resistance load (5), and the other end of the resistance load (5) is grounded with the driving module.

4. The circuit for sharing chip power by connecting a resistor in series with an LED according to claim 1, wherein: The driving module is a low-side driving chip, the power module (1) and the driving module are both connected to the positive electrode of the LED load (4), the negative electrode of the LED load (4) is connected to one end of the resistance load (5), and the other end of the resistance load (5) receives a control signal from the driving module.

5. The circuit for sharing chip power by connecting a resistor in series with an LED according to claim 2, wherein: Any LED load (4) is 1 to 4 LEDs connected in series.

6. The circuit for sharing chip power by connecting a resistor in series with an LED according to claim 3, wherein: The high-side driver chip is TPS929120, which has 12 output channels.

7. The circuit for sharing chip power by connecting a resistor in series with an LED according to claim 4, wherein: The low-side driver chip is TLD7002, which has 16 output channels.

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