Drive device and method for adjusting its own current, system based on drive device

Abstract

The present application relates to a driving device, a method for adjusting current of the driving device, and a system based on the driving device. The driving device comprises a power input end and a potential reference end, and further comprises a constant current unit capable of providing a driving current to a load to implement constant current driving on the load. A first bypass unit of the driving device is connected between the power input end and the potential reference end. In the case that there is a mismatch between the driving current set by any driving device and the driving current set by the remaining other driving devices under the premise that the driving devices are connected in series, the first bypass unit of the any driving device adaptively adjusts the current flowing therethrough, so as to ensure that the input currents flowing into different driving devices in the series architecture are equal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of constant current driving of loads, and more particularly to a driving device, a method for adjusting the current of the driving device, and a system based on the driving device. BACKGROUND

[0002] In the field of constant current driving of loads, the pulse modulation technique is commonly used in the art to change the time width of load energization or load de-energization within a determined time period, while requiring the current flowing through the load during load energization to be a constant current value, thereby achieving the change of the average current flowing through the load. If the output current flowing out of the current source driving the load is fixed, the driving of the load is referred to as current-fixed driving. If the output current flowing out of the current source driving the load is variable, the driving of the load is referred to as current-programmable driving. The difficulty lies in the deviation of the output current from the target value.

[0003] In the prior art, data transmission is usually performed in cascade using four communication lines, and the use of a clock signal line and a data signal line, as well as a load signal line and an output enable signal line, is the most typical four-line communication example. Whether it is four-line communication or two-line communication using only a clock signal line and a data signal line, or other numbers of multi-line communication, a very strict timing coordination relationship between different properties of signals transmitted on different signal lines is required to enable the communication process. In an alternative application example of multi-line communication is a single-line serial transmission scheme. Single-line transmission, as the name implies, requires only a single communication line, and has the advantage of simple wiring and freedom from the timing coordination constraints caused by traditional multi-line communication. In the field of constant current driving of loads, when there are a large number of loads and supporting current sources, a new driving scheme is urgently needed to solve the problem of current deviation. SUMMARY

[0004] The present application relates to a driving device, comprising:

[0005] a power input terminal and a potential reference terminal;

[0006] a constant current unit capable of providing a driving current to a load to implement constant current driving of the load;

[0007] a first bypass unit connected between the power input terminal and the potential reference terminal;

[0008] Under the premise that the driving devices are connected in series, when there is a mismatch between the driving current set by any driving device and the driving current set by the remaining driving devices, the first bypass unit of the any driving device adaptively adjusts the size of the current flowing therethrough to ensure that the input currents of the any driving device and the other driving devices are equal.

[0009] The above driving device further comprises a data transmission module and a pulse width modulation module.

[0010] The data transmission module is configured to collect the communication data.

[0011] The pulse width modulation module is configured to form a pulse width modulation signal according to the duty cycle information contained in the communication data, and the on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

[0012] The driving device further comprises a data transmission module configured to forward the communication data.

[0013] The multi-stage driving device collects the communication data in a cascaded manner, wherein each stage of the driving device extracts the communication data belonging to the stage and forwards the remaining communication data to the next stage connected in cascade after receiving the communication data.

[0014] The driving device further comprises a first bypass unit configured to adjust the voltage drop between the power input end and the potential reference end of the driving device while adjusting the current of the driving device.

[0015] The voltage drops of the different driving devices with the current mismatch are clamped at different voltage values.

[0016] The driving device further comprises a capacitor connected between the power input end and the potential reference end.

[0017] The driving device further comprises a first bypass unit configured to adjust the voltage drop between the power input end and the potential reference end of the driving device while adjusting the current of the driving device.

[0018] The manufacturing process of the driving device causes manufacturing differences between different driving devices.

[0019] The temperatures of different driving devices during operation are inconsistent.

[0020] The driving device further comprises a first bypass unit configured to adjust the voltage drop between the power input end and the potential reference end of the driving device while adjusting the current of the driving device.

[0021] The driving device further comprises a second bypass unit connected between the power input end and the potential reference end.

[0022] The second bypass unit is turned on when the voltage drop between the power input end and the potential reference end of the driving device is not lower than a second threshold voltage set by the second bypass unit, and is turned off otherwise.

[0023] The driving device: the first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input end and the potential reference end; and the first threshold voltage is determined by the minimum operating voltage required when the three-terminal adjustable shunt reference source is turned on.

[0024] The driving device: the second bypass unit includes a zener diode connected between the power input end and the potential reference end.

[0025] The second threshold voltage is determined by the critical voltage when the zener diode is reversely broken down.

[0026] The present application relates to a method for adjusting the current of a driving device, characterized in that:

[0027] The driving device includes: a power input end and a potential reference end; and a constant current unit capable of providing a driving current to a load.

[0028] A first bypass unit connected between the power input end and the potential reference end.

[0029] The method includes: connecting multiple driving devices in series.

[0030] Among the multiple driving devices, the current of the first bypass unit in a driving device with a larger driving current is smaller, and the current of the first bypass unit in a driving device with a smaller driving current is larger.

[0031] Therefore, the first bypass unit of each driving device can adaptively adjust the current flowing therethrough, so that the input current flowing into each driving device is equal.

[0032] The method: there is a voltage drop between the power input end and the potential reference end of each driving device; the voltage drop of a driving device with a larger driving current is smaller; and the voltage drop of a driving device with a smaller driving current is larger.

[0033] The method: when the voltage drop between the power input end and the potential reference end of a driving device is not lower than a first threshold voltage set by the first bypass unit: the first bypass unit is turned on, otherwise the first bypass unit is turned off.

[0034] The method: further includes a second bypass unit connected between the power input end and the potential reference end.

[0035] When the voltage drop between the power input end and the potential reference end of a driving device is not lower than a second threshold voltage set by the second bypass unit: the second bypass unit is turned on, otherwise the second bypass unit is turned off.

[0036] The first bypass unit comprises a three-terminal adjustable shunt reference source and a resistor connected in series between the power input end and the potential reference end, and a specified voltage or a preset voltage is input at the voltage reference end of the three-terminal adjustable shunt reference source; and the first threshold voltage is determined by the minimum operating voltage required when the three-terminal adjustable shunt reference source is turned on.

[0037] The second bypass unit comprises a zener diode connected between the power input end and the potential reference end.

[0038] The second threshold voltage is determined by the critical voltage when the zener diode is reversely broken down.

[0039] The driving device further comprises a capacitor connected between the power input end and the potential reference end.

[0040] When the voltage drop between the power input end and the potential reference end of any driving device is lower than the first threshold voltage, the constant current unit and the first bypass unit of the any driving device are turned off, and the capacitor of the any driving device is charged.

[0041] The method further comprises a data transmission module and a pulse width modulation module; the data transmission module collects communication data.

[0042] The pulse width modulation module forms a pulse width modulation signal according to the duty cycle information carried by the communication data, and the on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

[0043] The method further comprises a data transmission module, which is used to forward communication data.

[0044] The multi-stage driving device collects communication data in a cascaded manner: after each stage of driving device receives communication data, it extracts communication data belonging to the stage and forwards the remaining other communication data to the next stage connected in cascade.

[0045] The application relates to a driving device, which comprises:

[0046] a power input end and a potential reference end;

[0047] a constant current unit capable of providing a driving current to a load;

[0048] a first bypass unit connected between the power input end and the potential reference end;

[0049] The constant current unit and the first bypass unit are in parallel connection.

[0050] In the multi-stage driving device connected in series, the current of the first bypass unit in a driving device with a larger driving current is smaller, and the current of the first bypass unit in a driving device with a smaller driving current is larger.

[0051] Thus, the first bypass unit of each driving device can adaptively adjust the current flowing through itself, so that the input current of all driving devices is equal.

[0052] The driving device has a voltage drop between the power input end and the potential reference end of the driving device;

[0053] The driving device with a larger driving current has a smaller voltage drop;

[0054] The driving device with a smaller driving current has a larger voltage drop.

[0055] The driving device has a voltage drop between the power input end and the potential reference end of the driving device; when the voltage drop is not lower than a first threshold voltage set by the first bypass unit, the first bypass unit is turned on, otherwise the first bypass unit is turned off;

[0056] The first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input end and the potential reference end; the first threshold voltage is determined by the minimum operating voltage required when the three-terminal adjustable shunt reference source is turned on.

[0057] The driving device further has a capacitor connected between the power input end and the potential reference end;

[0058] When the voltage drop between the power input end and the potential reference end of any driving device is lower than the first threshold voltage, the constant current unit and the first bypass unit of the any driving device are turned off, and the capacitor of the any driving device is charged.

[0059] The driving device further includes a data transmission module and a pulse width modulation module;

[0060] The data transmission module is used to collect communication data;

[0061] The pulse width modulation module forms a pulse width modulation signal according to the duty cycle information carried by the communication data, and the on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

[0062] The driving device further includes a data transmission module, and the data transmission module is used to forward communication data;

[0063] The multi-stage driving device collects communication data in a cascaded manner; after each stage of driving device receives the communication data, the communication data belonging to the stage is extracted, and the remaining other communication data is forwarded to the next stage connected in cascade.

[0064] The present application relates to a system, comprising:

[0065] Multi-stage driving device in series connection in power supply mode

[0066] Each driving device comprises:

[0067] a power input end and a potential reference end;

[0068] a constant current unit capable of providing driving current to the load;

[0069] a data transmission module for collecting and forwarding communication data;

[0070] a first bypass unit connected between the power input end and the potential reference end;

[0071] a pulse width modulation module for forming a pulse width modulation signal according to duty cycle information contained in the communication data, and for controlling the on or off state of the constant current unit connected in series with the load by the pulse width modulation signal;

[0072] In the system:

[0073] The multi-stage driving device collects communication data in a cascaded manner, and each driving device extracts communication data belonging to the stage and forwards the remaining other communication data to the next stage connected in cascade after receiving the communication data;

[0074] When the driving current set by any driving device and the driving current set by the remaining other driving devices are different, the first bypass unit of the any driving device adaptively adjusts the current flowing through itself, thereby ensuring that the input current flowing into each of the different driving devices is equal.

[0075] In the above system, when the first bypass unit of the any driving device adjusts the current flowing through itself, it also synchronously adjusts the voltage drop between the power input end and the potential reference end of the any driving device:

[0076] The voltage drops of the different driving devices with different driving currents are clamped at different voltage values.

[0077] In the above system, in each driving device:

[0078] The first bypass unit comprises a three-terminal adjustable shunt reference source and a resistor connected in series between the power input end and the potential reference end; when the voltage drop between the power input end and the potential reference end is not lower than the minimum operating voltage required for the three-terminal adjustable shunt reference source to be turned on, the first bypass unit is turned on.

[0079] In the above system, in each driving device:

[0080] The second bypass unit is connected between the power input end and the potential reference end, and includes a voltage stabilizing circuit connected between the power input end and the potential reference end.

[0081] The system further comprises a capacitor connected between the power input end and the potential reference end.

[0082] The system further comprises a light emitting diode as the load.

[0083] The system further comprises a driving device in the form of a chip.

[0084] The application relates to a driving device, comprising:

[0085] A power input end and a potential reference end, and a voltage drop between the power input end and the potential reference end;

[0086] A constant current unit capable of providing a driving current to a load;

[0087] A first bypass unit connected between the power input end and the potential reference end;

[0088] When the voltage drop is not lower than a first threshold voltage set by the first bypass unit, the first bypass unit is turned on, and the driving device enters a first working mode, and the constant current unit is enabled;

[0089] When the voltage drop is lower than the first threshold voltage set by the first bypass unit, the first bypass unit is turned off, and the driving device enters a second working mode, and the constant current unit is disabled;

[0090] A plurality of driving devices are connected in series:

[0091] In the first working mode, if there is a difference between the driving current set by any one of the driving devices and the driving current set by the other driving devices, the first bypass unit of the any one of the driving devices adjusts the current flowing therethrough, so as to ensure that the input currents of the any one of the driving devices and the other driving devices are equal.

[0092] Meanwhile, the voltage drop of the any one of the driving devices is adjusted, so that the voltage drops of the different driving devices with the difference in the driving current are clamped at different voltage values.

[0093] The driving device further comprises a second bypass unit connected between the power input end and the potential reference end.

[0094] When the voltage drop is not lower than a second threshold voltage set by the second bypass unit, the first bypass unit and the second bypass unit are both turned on, the driving device enters a third working mode, and the second threshold voltage is greater than the first threshold voltage.

[0095] The driving device: the first bypass unit comprises a three-terminal adjustable shunt reference source and a resistor connected in series between the power input end and the potential reference end; the first threshold voltage is determined by the minimum operating voltage required for the three-terminal adjustable shunt reference source to be turned on;

[0096] The second bypass unit comprises a voltage stabilizing diode connected between the power input end and the potential reference end;

[0097] The second threshold voltage is determined by the critical voltage when the voltage stabilizing diode is reversely broken down.

[0098] The driving device: each driving device further has a capacitor connected between the power input end and the potential reference end;

[0099] When the driving device enters the second working mode, the capacitor of the driving device entering the second working mode is charged.

[0100] The driving device: each driving device further comprises a data transmission module and a pulse width modulation module;

[0101] The data transmission module is used to collect communication data;

[0102] The pulse width modulation module forms a pulse width modulation signal according to the duty cycle information carried by the communication data, and the on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

[0103] The driving device: each driving device further comprises a data transmission module, the data transmission module is used to forward communication data; the multi-stage driving device collects communication data in a cascaded manner: after each stage of driving device receives the communication data, the communication data belonging to the stage is extracted and the remaining other communication data is forwarded to the next stage connected in cascade.

[0104] The driving device: under the premise of the first working mode, the greater the driving current, the smaller the current of the first bypass unit in the driving device, and the smaller the driving current, the greater the current of the first bypass unit in the driving device. BRIEF DESCRIPTION OF DRAWINGS

[0105] In order to make the above-mentioned purposes and characteristics and advantages more obvious and easy to understand, the specific embodiments are described in detail below in combination with the drawings, and the characteristics and advantages of the present application will be apparent after reading the following detailed description and referring to the following drawings.

[0106] Figure 1Embodiment using current source module in architecture of multiple driving devices connected in series.

[0107] Figure 2 Embodiment without using current source module in architecture of multiple driving devices connected in series.

[0108] Figure 3 Example of communication data transmission in single wire mode in architecture of multiple driving devices connected in cascade.

[0109] Figure 4 Example of communication data transmission not synchronized in architecture of multiple driving devices connected in cascade.

[0110] Figure 5 Example of communication data transmission using RZ as communication protocol in architecture of multiple driving devices connected in cascade.

[0111] Figure 6 Driving device with data transmission module receiving duty cycle data and current regulation data.

[0112] Figure 7 Topology of driving device with first bypass unit and second bypass unit.

[0113] Figure 8 Waveform of input current of driving device in solving current mismatch problem.

[0114] Figure 9 Example of load driven by driving device can be light emitting or non-light emitting diode.

[0115] Figure 10 Example of multiple loads driven by same driving device controlled by pulse width modulation signal.

[0116] Figure 11 Example of optional electronic components of first bypass unit and second bypass unit in driving device.

[0117] Figure 12 Example of first bypass unit with three-terminal adjustable shunt reference source in driving device. DETAILED DESCRIPTION

[0118] The schemes of the present application will be described in detail below with reference to various embodiments. The schemes obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0119] Reference Figure 1, the master node not shown needs to send data DT to the slave nodes such as the driving device 100. The communication between the master node and the slave nodes can adopt a standardized communication protocol or a customized non-standardized communication protocol. The master node and the slave nodes are each configured with an interface circuit or a communication module for realizing data communication. The current common data communication adopts a plurality of transmission lines such as four lines to realize the transmission of communication signals: a clock signal line and a data signal line and a load signal line and an output enable signal line work together, and the communication data is transmitted in series one by one and the four-line signals cooperate with each other to realize the control of the slave nodes connected in cascade. The communication protocol using only three lines of data line, clock line and latch line is also the mainstream communication scheme of display technology. In the optional example, two-line transmission is adopted, and the two-line transmission of data line and clock line is a compromise between the number of data lines and the transmission rate. Although the common multi-line protocol is suitable for the communication between the master node and the slave nodes connected in cascade and the transmission of communication data, the alternative single-line communication technology is more suitable for the transmission of communication data, and the advantage of the single-line protocol is that the transmission of cascade data only needs a single data line. In the aspect of single-line transmission, the data transmission in the return-to-zero code encoding format or the data transmission in the return-to-zero code encoding format is the most common, and the Manchester code also belongs to the single-line transmission scheme. The communication mode under the condition of single-line transmission usually requires the slave nodes to have the function of data forwarding: for example, when each slave node receives the communication data transmitted by the master node, it needs to extract the data source belonging to its own unit first and forward other data sources not belonging to its own unit to the slave nodes connected in cascade behind it. The communication between the driving devices 100 requires a cascade connection relationship.

[0120] Referring to Figure 1 , the power input terminal VCC is usually defined as the power supply terminal of each functional module in the driving device 100, and the total input current flows from the power input terminal VCC. In contrast, the potential reference terminal GND is usually defined as the potential reference ground terminal of the driving device 100, and the total output current flows from the potential reference terminal GND. In the industry, in addition to the driving device which can be designed as a discrete driving circuit, it can also be designed as a driving chip with high integration.

[0121] Referring to Figure 1The power supply input terminal VCC of the first driving device 100 at the head of each column is coupled to the positive pole VP of the power supply, and the potential reference terminal GND of the last driving device 100 at the tail of each column is coupled to the negative pole VN of the power supply. The power supply input terminal of the next driving device in each column is coupled to the potential reference terminal of the previous driving device. In the example, the power supply input terminal VCC of the second driving device 100 in the first column is coupled to the current outflow terminal, i.e. the potential reference terminal GND, of the adjacent first driving device 100. The power supply input terminal VCC of the third driving device 100 in the first column is coupled to the current outflow terminal, i.e. the potential reference terminal GND, of the adjacent second driving device 100. For example, the power supply input terminal VCC of the fourth driving device 100 in the first column is coupled to the current outflow terminal, i.e. the potential reference terminal GND, of the adjacent third driving device 100. The power supply input terminal VCC of the last driving device 100 in the first column is coupled to the current outflow terminal, i.e. the potential reference terminal GND, of the second last driving device 100. For example, the power supply input terminal VCC of the second last driving device 100 in the first column is coupled to the current outflow terminal, i.e. the potential reference terminal GND, of the third last driving device 100. Thus, the power supply input terminal of the next driving device in each column is coupled to the potential reference terminal of the adjacent previous driving device, and all the driving devices in each column are connected in series between the positive pole VP and the negative pole VN of the external power supply. Optionally, a capacitor CZ can be arranged between the power supply input terminal VCC and the potential reference terminal GND of each driving device. It is considered that the output current of the previous driving device in each column is equivalent to the input current of the adjacent next driving device, or that the input current of all the driving devices in each column is equivalent, which is determined by the series connection of all the driving devices 100.

[0122] Referring to Figure 1 A current source module PCS is arranged in each column of driving devices, such as the first column, to maintain the input current of each driving device 100 in the first column at a predetermined value. In the first column, each driving device 100 and the current source module PCS are connected in series between the positive pole and the negative pole of the power supply. The input current of any one of the driving devices in each column is equal to the output current of the current source module PCS, and this is true for the left-hand first column and the right-hand second column.

[0123] Referring to Figure 1During the stage where each drive device 100 updates its communication data from the previous frame of communication data to the next frame, the current regulation data received by the current source module PCS is also refreshed frame by frame, so that the output current of the current source module PCS is also refreshed frame by frame and flows to the drive device. The input current of each drive device is updated from a predetermined value corresponding to the current regulation data of the previous frame to a predetermined value corresponding to the current regulation data of the next frame. Note that the current regulation data of the previous frame is decoded from the previous frame of communication data, and the current regulation data of the next frame is decoded from the next frame of communication data. At this time, both the current source module PCS and the drive device include a communication interface circuit or communication module for transmitting and receiving communication data, but the communication data received by the current source module PCS is defined as current regulation data according to its purpose. The current source module PCS can limit the input current of the drive device. If the current source module PCS shown in the figure omits the communication interface circuit or communication module, its output current is fixed, that is, the current source module PCS naturally does not need the signal output terminal DO and signal input terminal DI shown in the figure.

[0124] See Figure 1 Using a current source module (PCS) presents several insurmountable drawbacks. Firstly, current regulation data is part of the complete data set, occupying additional data bits in each frame, leading to data bloat and reducing the refresh rate of communication data sent to each driver. Secondly, the PCS incurs additional high costs, especially given the extremely high current accuracy required. Furthermore, the PCS is a completely different electronic component from the connected drivers; voltage fluctuations between the positive (VP) and negative (VN) terminals of the external power supply are largely handled by the PCS, making it prone to overheating and damage. Therefore, it is essential to omit the PCS due to these drawbacks, as will be discussed later.

[0125] See Figure 2 The explanation will still utilize a cascaded multi-stage drive unit 100. Note that the cascaded drive unit described above is configured in a column form in terms of power supply, i.e., the drive units are connected in series. The master node sends communication data to each stage of the drive unit, and the master node can use a data transmission terminal such as a server or microprocessor. When sending communication data to multiple drive units that appear in a cascaded manner: the signal output terminal DO of the previous stage or the next stage drive unit can be configured to be coupled to the signal input terminal DI of the next stage or the next stage drive unit through a coupling capacitor C.

[0126] See Figure 2The various drive devices 100 are configured in a cascaded communication configuration. The signal input terminal DI of the first drive device 100, which is the head of the first column, receives communication data from the master node. The first column also includes a signal output terminal DO of a preceding drive device coupled to the signal input terminal DI of a subsequent drive device. For example, the signal input terminal DI of the second drive device 100 in the first column is coupled to the signal output terminal DO of the adjacent first drive device 100, i.e., the preceding stage drive device. This pattern continues with the cascading of the drive devices; for example, the signal input terminal DI of the third drive device 100 in the first column is coupled to the signal output terminal DO of the adjacent second drive device 100, i.e., the preceding stage drive device. Similarly, the signal input terminal DI of the fourth drive device 100 in the first column is coupled to the signal output terminal DO of the adjacent third drive device 100, i.e., the preceding stage drive device. If the last drive device 100 in the first column is the final drive device among many drive devices, its signal output terminal DO can float. If the tail drive device 100 is not the final drive device among many drive devices, its signal output terminal DO can continue to transmit communication data to the next stage.

[0127] See Figure 2 The various drive devices 100 are configured in a cascaded communication configuration. In the second column, the signal output terminal DO of the preceding drive device is coupled to the signal input terminal DI of the following drive device. For example, in the second column, the signal output terminal DO of the second drive device 100 is coupled to the signal input terminal DI of the adjacent first drive device 100, i.e., the next stage drive device. This pattern continues with the cascading of the drive devices; for example, in the second column, the signal output terminal DO of the third drive device 100 is coupled to the signal input terminal DI of the adjacent second drive device 100, i.e., the next stage drive device. Similarly, in the second column, the signal output terminal DO of the fourth drive device 100 is coupled to the signal input terminal DI of the adjacent third drive device 100, i.e., the next stage drive device. The last drive device 100 in the second column, acting as the tail of the column, is allowed to receive communication data originating from the last drive device 100 in the first column, and similarly, the last drive device 100 in the second column, acting as the tail of the column, is also allowed to receive communication data originating from the primary node. The communication data in the first column on the left is transmitted from the beginning of the column to the end, while the communication data in the second column on the right is transmitted from the end of the column to the beginning.

[0128] See Figure 3Taking data transmission in return-to-zero (RZ) code format as an example: Assume N (N is a positive integer greater than 1) drive devices are cascaded together, and each drive device is allocated communication data D1 to DN. After the first drive device receives communication data D1 from the master node, it will also receive communication data D2-DN, but it will forward D2-DN to the second drive device, retaining only communication data D1. The second drive device will also receive communication data D2-DN, but it will forward D3-DN to the third drive device, retaining only communication data D2. Similarly, the third drive device will receive communication data D3-DN, but it will forward D4-DN to the fourth drive device, retaining only communication data D3. This continues until the last drive device 100 at the end of the line receives communication data DN. It is clear that the complete data DT, including D1-DN, is not synchronously allocated to the N cascaded drive devices 100. Additionally, it can be learned that multi-stage drive units receive communication data in a cascaded manner: after each drive unit receives communication data, it extracts the communication data belonging to its own stage and forwards the remaining communication data to the next stage connected to it in the cascade.

[0129] See Figure 3 Taking a three-level drive system (N=3) as an example, each drive system is allocated 24 bits of communication data. After the first drive system receives the first batch of 24 bits of data from the master node, it then receives the second batch. However, since the first drive system has already reached its required total number of bits, it will directly forward the second batch to the second drive system. The first drive system then receives the third batch of 24 bits of data from the master node. This third batch is then forwarded to the second drive system according to the forwarding rules. Because the second drive system has already met its required total number of bits, and the second batch of 24 bits was allocated to it, the second drive system will then forward the third batch to the third drive system.

[0130] See Figure 3The drawback of asynchronous communication data among N drive devices 100 is as follows: Assuming the communication data packet contains current regulation data sent to the drive devices that can be used to change the magnitude of the drive current IS, the drive device that receives the communication data first will change its own drive current IS after receiving the data, and the drive devices that receive the communication data later will also change their own drive current IS. During the stage where each drive device 100 receives the previous frame of communication data and updates to the next frame: for example, after the first drive device in the cascade position (the head drive device 100) updates to the next frame of communication data and changes its own drive current IS, the drive devices in the cascade position that are relatively later, such as the tail drive device 100, have not yet updated to the next frame of communication data. Obviously, at this time, the drive current IS of the tail drive device 100 is still determined by the previous frame of communication data. Therefore, the drive current IS provided by drive devices in different cascade positions will differ. If it is stipulated that the drive current set by any drive device should be equal to the drive current set by the remaining drive devices, then the difference between the drive current set by any drive device and the drive current set by the other drive devices constitutes a mismatch. Considering that the N drive devices 100 are connected in series, in an optional example, if the drive current IS provided by all drive devices 100 is equal, it can sufficiently ensure that the input current flowing into each different drive device is equal. Conversely, if there are differences in the drive current IS provided by different drive devices, it may cause current mismatch in a series architecture, because the input current of all drive devices 100 connected in a series architecture should be exactly the same. The drive current IS will be further discussed below.

[0131] See Figure 5Return-to-zero (RZ) code format data transmission allows the use of the reset signal RESET. In many cases, the reset signal is essentially a easily detectable long low level. Upon receiving the RESET signal, each driver 100 directly forwards it to the other cascaded downstream driver 100s. Each driver 100, upon receiving the RESET signal, triggers an update of its own communication data. If the RESET signal is used as the refresh time point for triggering the drive current IS, its advantage is that it can reduce the time difference between the data refresh times of the N cascaded driver 100s. However, the reset signal is still transmitted from the driver 100 earlier in the cascade to the driver 100 later in the cascade. Therefore, the driver 100 that receives the reset signal first will change the magnitude of its own drive current IS after receiving the reset signal, and the driver 100 that receives the reset signal later will also change the magnitude of its own drive current IS after receiving the reset signal. That is, the refresh times of the communication data of the N driver 100s are still asynchronous, and the potential threat of mismatch in the cascaded current still exists. If the master node sends a so-called reset signal, all cascaded drive devices will reset, decode and refresh the communication data they have received, and execute it, completing a data refresh cycle and returning to the data receiving preparation state.

[0132] See Figure 4 Given that the communication data of the N drive devices 100 are not synchronized: the drive device that receives the communication data first will slightly delay changing its own drive current IS after receiving the reset signal; the drive devices that receive the reset signal later and the drive devices that receive the reset signal first will try to synchronize the change of the drive current IS value. Note that data transmission in normalized code format, return-to-zero code format, Manchester code, etc., will all cause synchronization issues.

[0133] See Figure 4For example, the first drive device 100 receives the reset signal RESET and changes its drive current IS only after a delay of T1. The second drive device 100 receives the reset signal RESET and changes its drive current IS only after a delay of T2. The third drive device 100 receives the reset signal RESET and changes its drive current IS only after a delay of T3, and so on. The Nth drive device 100 has no delay. The earlier the drive device is in the cascade, the longer the delay period needs to be: the N drive devices can refresh their respective drive current IS almost synchronously. The drive devices need to be configured with additional timers to perform the delay timing. The rule of this example is: by delaying, all drive devices should refresh the communication data at the same time as possible. Since the communication data includes current regulation data, the N drive devices should refresh their respective drive current IS at the same time as possible. However, it is worth emphasizing that whether using a reset signal or further using delay, it only reduces or slows down the time difference between the effective time points of the communication data refresh of the N drive devices 100, and cannot completely solve the current mismatch problem.

[0134] See Figure 6 The data transmission module (COM) of the drive device has a decoding function, including a decoder that can decode input serial data according to a preset communication protocol. For example, the drive device can decode either type I data or type II data from received communication data. In fact, both type I and type II data are converted back into ordinary binary data by the decoder, which restores signals with preset encoding rules from the communication data. The restored data differs slightly in their uses, hence the naming conventions also differ. The data transmission module (COM) is essentially the interface circuit or communication module mentioned earlier that enables data communication. Type I data includes current regulation data that adjusts the drive current, while type II data includes data containing duty cycle information or pulse width modulation data.

[0135] See Figure 6 A programmable constant current unit is configured. The adjustment scheme for the driving current IS provided by the constant current unit CS1 is diverse. The first type of data decoded by the drive device 100 and allocated to the constant current unit CS1 is represented as D1-CS in the figure. When the data transmission module COM receives communication data, it decodes the first type of data, such as current adjustment data, and this first type of data is used to fine-tune or adjust the constant current IS of the constant current unit. That is, the data transmission module can receive communication data containing the first type of data, and the first type of data is transmitted to the constant current unit CS1. The technique of using binary values ​​to fine-tune the current value is well known to those skilled in the art, so it will not be described further in this application.

[0136] See Figure 6The constant current unit and current source are also called constant current source modules (CurrentSource), and the generated stable reference current or constant current is regarded as the driving current IS. Connecting the load or light source in series with the constant current source module can stabilize their current and achieve constant current control. Alternatively, a current mirror structure can be used to match the constant current source module so that the current flowing through the current mirror is either equal to or proportional to the reference current. The current mirror (CurrentMirror) is a specific form of constant current source module, and its mirror current is equal to or proportional to the input reference current. Its characteristic is that the mirror current flowing through the current mirror is a copy of the input reference current at a certain ratio. Therefore, allowing the mirror current to flow through the load or light source can also implement constant current drive for the load or light source. In this application, any circuit that can generate a stable reference current or constant current can be classified as a constant current unit CS1. Constant current source modules such as voltage-to-current converters are optional examples of constant current units or current sources. It can be seen that the circuit topologies of constant current units or current sources that generate constant output current shown in the figure are not unique but diverse.

[0137] See Figure 6 This allows for cascading between driver devices and other communication circuits, as well as cascading between driver devices themselves; therefore, they all possess data forwarding capabilities. One of the core functions of a driver device is to drive its associated single-channel or multi-channel load and provide constant current drive as required. The data transmission module configured in the driver device has a decoder that decodes the input serial data according to a preset communication protocol and decodes various types of data from the received communication data. In the optional example, taking the data decoding and data forwarding functions as an example, we will explain the mechanism by which the data transmission module COM receives and forwards communication data. The signal input terminal DI receives externally provided communication data. The decoder needs to decode or decode the data information carried in the communication data. The significance of data decoding is that it can restore the pre-encoded data that the driver device cannot directly use into conventional binary code that is easy to recognize and execute. The decoded binary code can be temporarily stored in a register. Considering that the data refresh of the register may be relatively fast and frequently updated, additional buffer space or latches can be used to store the decoded data. Encoding formats such as Manchester encoding / decoding, normalized-to-one encoding / decoding, and return-to-zero encoding / decoding are suitable for single-line data transmission protocols or communication protocols of data transmission modules.

[0138] See Figure 6The so-called Data Transmission Module (COM) is responsible for data regeneration or forwarding, completing tasks such as transmitting communication data to downstream driver devices. The simplest forwarding mode of the COM is pass-through, allowing communication data received at the input terminal (DI) to be directly output from the output terminal (DO). Cascaded driver devices or other communication circuits then extract their own communication data from individual data lines according to address allocation rules. An alternative forwarding scheme requires statistical analysis of the communication data belonging to each driver stage. Each driver stage extracts its own communication data from each frame and forwards the remaining data to its cascaded downstream receiver, which can be a downstream driver device or other communication circuit. For example, each driver stage needs to statistically analyze whether the total number of bits belonging to its stage has been completely received. If the communication data belonging to its stage is decoded and completely received, the COM will trigger the data transmission module to remove the communication data received at the input terminal (DI) from the output terminal (DO). The data forwarding process also allows for data shaping: because signal attenuation occurs during the forwarding phase of multi-stage drive devices, the more cascaded the drive devices, the more severe the signal distortion and attenuation. Therefore, data shaping can be performed during forwarding. For example, return-to-zero (RZ) or return-to-one (RBO) codes require each bit of communication data to meet a predetermined duty cycle during transmission. To ensure no data attenuation, the duty cycle of each bit's high or low level is reconstructed during transmission. Shaping forwarding is equivalent to: each bit of data with a predetermined duty cycle is first received and decoded by the data transmission module COM. The data transmission module COM then adjusts the duty cycle of each bit until it is restored to the predetermined duty cycle. That is, the predetermined duty cycle of each bit of data received by the signal input terminal DI of the data transmission module COM and the actual duty cycle of each bit of data forwarded and output by the signal output terminal DO of the data transmission module COM are roughly equal. By shaping the data, signal attenuation and distortion are recovered. As an alternative forwarding scheme, an encoder can be configured on the data transmission module (COM) and re-encoding technology can be used to achieve forwarding: after the communication data is decoded and temporarily stored in the storage space of the data transmission module (COM), the encoder, which can re-encode the binary data, re-encodes the temporarily stored data and outputs it. This relay function of data decoding and storage and re-encoding output according to a predetermined encoding format ensures that the data can be transmitted smoothly. Data forwarding falls within the scope of existing technology.

[0139] See Figure 6The drive unit 100 includes a power input terminal VCC and a potential reference terminal GND, and also includes a load LOAD and a constant current unit CS1 connected in series between the power input terminal VCC and the potential reference terminal GND. Note that current flows in from the power input terminal VCC and flows out from the potential reference terminal GND. The drive unit 100 can function as a drive circuit that provides constant current drive for loads such as conventional diodes, light-emitting diodes, or resistors, or as a battery charging management circuit that manages loads such as rechargeable batteries. In the industry, in addition to the components mentioned above, the drive unit 100 may, as optional rather than mandatory, integrate protection circuits such as over-temperature protection, startup protection, electrostatic discharge protection, transient voltage protection, or spike current discharge circuits, as well as bandgap circuits, and integrate oscillators, power-on reset circuits, clock circuits, or communication modules. These modules or circuits are necessary or optional parts of the drive unit for constant current drive of the load, especially when the drive unit is a highly integrated drive chip. Since these aspects are well known to those skilled in the art, they will not be elaborated further.

[0140] See Figure 6The drive current IS generated by the constant current unit CS1 typically employs pulse width modulation (PWM) to drive the load LOAD. The PWM module MOD shown in the diagram generates a PWM signal and controls the on / off state of the constant current unit IS. The full-amplitude drive current IS is applied to the load LOAD as a repetitive pulse sequence of on / off states: when IS is on (e.g., when the PWM signal is high), the drive current IS is output and applied to the load LOAD; conversely, when IS is off (e.g., when the PWM signal is low), the drive current IS is disconnected from the load LOAD. PWM is a prior art technique. The communication data received by the drive device includes a second type of data, i.e., PWM data, represented as D1-GS in the diagram. Based on the second type of data matched to the load LOAD, the drive device determines and provides the duty cycle of the drive current IS to be output to the load LOAD. The drive current IS is periodically modulated by on / off switching with the given duty cycle. In other words, the pulse width modulation module MOD uses second-type data carrying duty cycle information to form a so-called pulse width modulation signal (PWM). The on / off state of the constant current unit CS1, which is connected in series with the load LOAD, is controlled by the PWM signal. The complete communication data received by the drive device 100 includes high-order data segments and low-order data segments. The first-type data and the second-type data can be selected from the high-order data segment and the low-order data segment of the communication data, or vice versa. If the drive current of the load LOAD is 80mA and the duty cycle of the conduction time determined by the PWM signal is 75%, then the equivalent average current is 80 × 75% = 60mA. If the drive current output by the drive device is adjusted to 60mA through communication data and the duty cycle of the conduction time determined by the PWM signal is 70%, then the equivalent average current of the adjusted drive current is 60 × 70% = 42mA. The constant current unit can be flexibly programmed for the current.

[0141] See Figure 7A non-programmable constant current unit is configured. The magnitude of the drive current IS provided by the constant current unit CS1 is pre-programmed into the constant current unit CS1. For example, the drive current magnitude of drive devices of the drive chip type is usually predetermined before leaving the factory. At this time, the first type of data, i.e., the data originally expressed as D1-CS, can be ignored. In this example, the drive current does not need to be edited and modified online through communication data. Note that the manufacturing process of the drive device 100 can easily lead to manufacturing differences between different drive devices: for example, some drive devices are not from the same batch, so their drive currents are different; for example, some drive devices have different drive currents due to slight changes in the manufacturing process; for example, the size or doping concentration of some transistors or electronic components in the constant current unit containing many semiconductor transistors and electronic components may deviate, which may all lead to different drive devices having different drive currents. In addition, inconsistent operating temperatures of the drive devices can also cause drive current mismatch.

[0142] See Figure 7 In an optional example, a first bypass unit SH1, as shown in the figure, is connected between the power input terminal VCC and the potential reference terminal GND. This is connected in series in the multi-stage drive unit 100. Figure 3 Under the premise of ), the function of the so-called first bypass unit SH1 is set as follows: when there is a mismatch between the drive current IS set by any drive device and the drive current IS set by other drive devices, the first bypass unit SH1 in any drive device adaptively adjusts the magnitude of the current flowing through itself to ensure that the input current of any drive device and other drive devices are equal, or in other words, to ensure that the input current flowing into each different drive device is equal.

[0143] See Figure 3 In an optional example, consider an N-level drive unit. In a series drive unit link, it can be assumed that the drive unit 100 at the head of the column deviates from its design specifications, resulting in a drive current IS of 11mA. For example, it can be assumed that a drive unit 100 in the middle deviates from its design specifications, resulting in a drive current IS of 10mA. Furthermore, it can be assumed that the drive unit 100 at the tail of the column deviates from its design specifications, resulting in a drive current IS of 13mA. Undoubtedly, there is a drive current mismatch between the drive current IS of the so-called head drive unit 100 and the drive currents of the middle and tail drive units 100, even though they should ideally have the same desired current value. Differences in the drive current IS provided by different drive units in a series drive unit architecture can cause cascade current ISE disturbances. In a series architecture, the input current of all series-connected drive units 100 should be exactly the same.

[0144] See Figure 3In a multi-stage drive system connected in series, when there is a mismatch between the drive current IS set by any drive device (such as the head drive device 100) and the drive current IS set by other drive devices (such as the tail drive device), the first bypass unit SH1 in the head drive device 100 must adaptively adjust its own current to ensure that the input current flowing into each drive device is equal. For example, if the drive current IS set by the head drive device 100 is lower than the drive current IS of other drive devices (such as the tail drive device), then the so-called first bypass unit SH1 in the head drive device should increase its current to make the input currents of the head and tail drive devices equal. Conversely, if the drive current IS set by the head drive device 100 is higher than the drive current IS set by other drive devices (such as the tail drive device), then the so-called first bypass unit SH1 in the head drive device should decrease its own current to make the input currents of the head and tail drive devices equal, both equal to the cascade current ISE. The principle is that the current of the first bypass unit SH1 in a drive device with a smaller drive current is larger, and at the same time, the current of the first bypass unit SH1 in a drive device with a larger drive current is smaller. The first bypass unit SH1 is required to be able to adjust its own current.

[0145] See Figure 3 In a multi-stage drive unit connected in series: when there is a mismatch between the drive current IS set by any drive unit, such as the third drive unit 100, and the drive current IS set by other drive units, such as the sixth drive unit, the first bypass unit SH1 in that drive unit, such as the third drive unit 100, is required to adaptively adjust its own current to ensure that the input current flowing into each drive unit is equal. For example, if the drive current IS set by the third drive unit 100 is lower than the drive current IS set by other drive units, such as the sixth drive unit, the so-called first bypass unit SH1 in the third drive unit should increase the current to make the input currents of the third and sixth drive units equal. Conversely, if the drive current IS set by the third drive unit 100 is higher than the drive current IS set by other drive units, such as the sixth drive unit, the so-called first bypass unit SH1 in the third drive unit should decrease the current to make the input currents of the third and sixth drive units equal, and both equal to the cascade current ISE.

[0146] See Figure 3The mismatch mechanism involves the asynchronous reception of communication data by multiple driving units: when the previous frame of communication data sent to the cascaded multi-stage driving units is updated to the next frame, the first type of data of some driving units has already been updated according to the next frame, while the first type of data of other driving units is still determined by the previous frame. Consequently, in a series-connected multi-stage driving unit architecture, there is a mismatch between the drive current set by some driving units and the drive current set by others. The earlier the cascade position, the earlier the communication data is received; the later the cascade position, the later the communication data is received. The mechanism for the difference between the drive current set by any driving unit and the drive current set by other driving units includes: the multi-stage driving units receive their communication data asynchronously, and this difference is basically similar to the aforementioned mismatch principle.

[0147] See Figure 7 In an optional example, a second bypass unit SH2, as shown in the figure, is connected between the power input terminal VCC and the potential reference terminal GND. This is achieved by connecting the multi-stage drive unit 100 in series. Figure 3 Under the premise of [condition], the function of the so-called second bypass unit SH2 is defined as follows: when the voltage drop between the power input terminal VCC of the drive device and the potential reference terminal GND exceeds the second threshold voltage or critical voltage set by the second bypass unit SH2, the second bypass unit SH2 is turned on to play a role in voltage stabilization and current shunting, preventing damage to the drive device. The second bypass unit SH2 is optional rather than mandatory, so much so that in some embodiments, the second bypass unit SH2 can be directly omitted.

[0148] See Figure 3 In an optional example, the cascade current flowing through each drive unit is ISE. When there is a mismatch between the drive current IS set by any drive unit and the drive current IS set by the remaining drive units, the so-called first bypass unit SH1 in that drive unit adaptively adjusts its own current to ensure that the input current flowing into each drive unit is equal, which is the cascade current ISE. When the drive current IS set by any drive unit is lower than the drive current IS set by the remaining drive units, its first bypass unit SH1 increases the current; conversely, when the drive current IS set by any drive unit is higher than the drive current IS set by the other drive units, its first bypass unit SH1 decreases the current flowing through it. The current of the first bypass unit SH1 of any drive unit may continuously and dynamically change to automatically adapt to the aforementioned mismatch in drive current within that drive unit. The method by which the drive unit adjusts its own current is to adjust the input current or output current of the drive unit to be equal to or follow the cascade current ISE.

[0149] See Figure 8In the optional examples, Figures 2-3 The input or output current of any chosen drive device 100 can be approximated by curve 108 shown in the figure. In this coordinate system, the horizontal axis approximates the voltage drop between the power input terminal VCC and the potential reference terminal GND of the drive device, while the vertical axis approximates the current level of the input current flowing into the drive device or the output current flowing out. The input current of the drive device flows in from the power input terminal VCC, and the output current flows out from the potential reference terminal GND. The input current of the drive device is equal to its output current and should also be equal to the cascade current ISE flowing through the series-connected multi-stage drive devices. If the first type of data mentioned above, namely current adjustment data, is used to fine-tune the value of the drive current IS, for example, adjusting the drive current value to a relatively small level, it can be approximated by curve 208 shown in the figure. The drive current value represented by curve 208 is significantly smaller than the drive current value represented by curve 108. This article takes curve 108 as the research object and discusses the mismatch problem of drive current IS in the following content. Note that if the drive current is pre-programmed, it does not need to be edited and modified online through communication data, and curve 208 in the figure can also be ignored.

[0150] See Figure 8 In the optional examples, combined Figure 3 In a series-connected multi-stage drive system: when the drive current IS set by any drive device causes the input current of that drive device to tend to be lower than the aforementioned cascade current ISE flowing through the series-connected multi-stage drive system, the first bypass unit SH1 in that drive device adaptively increases its current. This ensures that the input current of that drive device remains equal to the cascade current ISE. For example, if the drive current IS set by the first drive device in the series is 12mA, and the cascade current ISE is constrained by the drive current IS set by the remaining drive devices, assuming that the drive current IS of the other drive devices is around 15mA, then the input current of the first drive device in the series tends to be lower than the cascade current ISE. In this case, the first bypass unit SH1 in the first drive device in the series should adaptively increase its current to overcome the aforementioned negative trend. The right side of the inflection point N1 on the curve 108 representing the input current of the drive device is where the first bypass unit SH1 begins to conduct, so that the input current of the drive device will change slightly to overcome the negative impact caused by the difference in drive current IS. Since the drive current IS of other drive devices is set at a slightly higher level of around 15mA, the first bypass unit SH1 of other drive devices may also adaptively reduce the current in accordance with the rules of this application to ensure that the input current of different drive devices is equal.

[0151] See Figure 8 In the optional examples, combinedFigure 3 In a series-connected multi-stage drive system: when the drive current IS set by any drive device causes the input current of that drive device to tend to be higher than the aforementioned cascade current ISE flowing through the series-connected multi-stage drive system, the first bypass unit SH1 in that drive device adaptively reduces the current. This ensures that the input current of that drive device can still be maintained at the level of the cascade current ISE. For example, if the drive current IS set by the first drive device in the column is 14mA, and the cascade current ISE is constrained by the drive current IS set by the remaining drive devices, assuming that the drive current IS of the other drive devices is around 10mA, then the input current of the first drive device in the column tends to be higher than the cascade current ISE. In this case, the first bypass unit SH1 in the first drive device in the column should adaptively reduce the current to overcome the aforementioned negative trend. The left side of the inflection point N1 on the curve 108 representing the input current of the drive device is where the first bypass unit SH1 begins to turn off. Since the drive current IS of other drive devices is set at a slightly lower 10mA, the first bypass unit SH1 of other drive devices may also adaptively increase the current according to the rules of this application to ensure that the input current of different drive devices is equal.

[0152] See Figure 8 In the optional examples, combined Figure 3 Typically, there is a decrease in voltage drop between the power input terminal VCC and the so-called potential reference terminal GND of the drive device. Various factors can cause this decrease in voltage drop, such as a drop in the power supply voltage. For example, in a series-connected multi-stage drive device, some drive devices may have a larger share of the external power supply voltage drop, while others may have a smaller share—that is, the voltage distribution is uneven. The voltage drop of the drive devices with a smaller share of the external power supply voltage will naturally tend to be lower. This decrease in voltage drop is often accompanied by a decrease in both the input and output currents of the drive device. Observing the left side of the inflection point N1 on curve 108, we can see that the voltage drop has decreased. The charging behavior of the capacitor CZ connected between the power input terminal and the potential reference terminal of the drive device can prevent excessive voltage drop. Solution for the problem of reduced voltage drop causing abnormal operation of the drive device: If the constant current unit CS1 and the first bypass unit SH1 are turned off, the capacitor CZ will be forced to charge. Charging means that the voltage drop will increase and the drive device may return to the inflection point N1. However, the drive device is in an undervoltage state. The increase in voltage drop will be interrupted and will fall back to the left of the inflection point N1, causing the input and output current to tend to decrease. According to the design rules, the constant current unit CS1 and the first bypass unit SH1 need to be turned off again to charge the capacitor CZ. This cycle continues.

[0153] SeeFigure 8 In the optional examples, combined Figure 7 When the voltage drop between the power input terminal and the potential reference terminal of the drive device exceeds the second threshold voltage or critical voltage set by the second bypass unit SH2, the second bypass unit SH2 is turned on, thereby performing voltage regulation and current shunting functions. On the curve 108 representing the input current of the drive device, to the right of inflection point N2, a sharp increase in input current can be observed. The right side of inflection point N2 indicates that the voltage drop of the drive device is at a very high level, sufficient to trigger the second bypass unit SH2 to turn on; to the left of inflection point N2, the second bypass unit SH2 is turned off. In an optional example, the second bypass unit SH2 includes a conventional voltage regulator circuit with a second threshold voltage, which is turned on when the voltage drop exceeds the second threshold voltage set by the second bypass unit SH2.

[0154] See Figure 8 In the optional examples, combined Figure 3 Multiple drive units are connected in series. When there is a difference between the drive current IS set by any drive unit and the drive current IS set by the remaining drive units, the first bypass unit SH1 in that drive unit adaptively increases or decreases the current, thereby ensuring that the input current flowing into each of the different drive units connected in series is equal. In a preferred example, the current of the first bypass unit of any drive unit is allowed to continuously and automatically increase or decrease dynamically, so that the drive unit automatically adapts to the existing mismatch. For example, if any drive unit operates between the inflection point N1 and the inflection point N2 shown in the figure: the continuous automatic and dynamic increase or decrease of the current of its first bypass unit SH1 means that the input current of the drive unit follows the cascade current ISE. In fact, this current self-adjustment is also a process in which each drive unit finds its own suitable voltage operating point.

[0155] See Figure 9 For ease of explanation, a three-channel LED load is illustrated. The specific number of loads is for reference only and is not a limitation. See Figure 10The data transmission module COM decodes multiple sets of second-type data from the communication data. The first pulse width modulation module MOD1 then generates a first pulse width modulation signal (PWM1) corresponding to the first LED (R) based on the second-type data allocated to it. Similarly, the second pulse width modulation module MOD2 generates a second pulse width modulation signal (PWM2) corresponding to the second LED (G) based on the second-type data allocated to it. Likewise, the third pulse width modulation module MOD3 generates a third pulse width modulation signal (PWM3) corresponding to the third LED (B) based on the second-type data allocated to it. Thus, each pulse width modulation module in the drive device generates a corresponding pulse width modulation signal based on the second-type data matched to its corresponding or paired LED. Specifically, each pulse width modulation module generates a pulse width modulation signal corresponding to each LED based on the second-type data allocated to it. In addition to red, green, and blue primary color light sources, multi-channel LEDs can also include white LEDs, or alternative solutions such as two green LEDs plus red and blue LEDs. If the lighting display scene requires more LED light sources, the number of LED channels can be increased to more LEDs; if the lighting display scene requires fewer LED light sources, the number of LED channels can be reduced to one or two LEDs. The second type of data includes data containing duty cycle information or grayscale data, while the first type of data includes current adjustment data. Representing the first to third pulse width modulation modules described above are the pulse width modulation modules MOD1-3 shown in the figure.

[0156] See Figure 10The LEDs are connected in series with a common constant current unit. The first LED (R) is connected in series with the common constant current unit CS1 via its corresponding first switch S1; the second LED (G) is connected in series with the common constant current unit CS1 via its corresponding second switch S2; and the third LED (B) is connected in series with the common constant current unit CS1 via its corresponding third switch S3. When a valid logic level is reached for any one of the LEDs' corresponding pulse width modulation signals, the common constant current unit CS1 is activated, and any LED switches to be connected in series with the common constant current unit CS1 and illuminates. For example, when the first pulse width modulation signal reaches a valid logic level (e.g., a high level), the first switch S1 is turned on, further activating the common constant current unit CS1 and activating the first LED (R). Similarly, when the second pulse width modulation signal reaches a valid logic value (e.g., a high level), the second switch S2 is turned on, further activating the common constant current unit CS1 and activating the second LED (G) in series with the common constant current unit CS1 and activating it. When the third pulse width modulation signal reaches a valid logic level (e.g., high), the third switch S3 is turned on, further enabling the constant current unit CS1 and illuminating the third LED (B), which is connected in series with the common constant current unit CS1. The valid logic levels of the first to third pulse width modulation signals are set to non-overlapping, meaning the three LEDs do not illuminate simultaneously. This type of load combination of three LEDs can constitute a basic pixel. Figure 9 This can be used to display the area.

[0157] See Figure 10When using the first to third pulse width modulation signals PWM1-PWM3 described above, the single cycle time of the pulse width modulation signal is divided into three sub-time periods, and the effective logic level of each pulse width modulation signal is allocated within the corresponding sub-time period. The result of the NOR operation of the first to third pulse width modulation signals PWM1-PWM3 is regarded as the control signal DX of the bypass module. When the control signal DX has a valid logic level, such as a high level, it triggers the conduction of the parallel branch, for example, the conventional resistor W of the parallel branch is turned on. The input terminals of the NOR gate 300 are respectively input to the first to third pulse width modulation signals PWM1-PWM3, etc., and the control signal DX output by the NOR gate 300 is used to control whether the parallel branch is turned on. The conventional resistor W of the parallel branch is connected in series with the common constant current unit CS1 through its corresponding fourth switch S4. Similarly, when the control signal DX has a valid logic level, such as a high level, the fourth switch S4 is turned on, which further enables the common constant current unit CS1 and switches the conventional resistor W to be connected in series with the constant current unit CS1 and energized. Alternatives to conventional resistors W, such as light-emitting diodes or non-light-emitting conventional diodes, or even active loads such as MOSFETs with diode connections, are all permissible load forms.

[0158] See Figure 10 In an optional example, using a driver that drives the first to third LEDs as an example, the scheme of this example is illustrated. The result of the NOR operation performed on the pulse width modulation signals PWM1-PWM3 is regarded as the control signal DX of the parallel branch. During the first sub-time period of a single cycle, the low level of the first pulse width modulation signal PWM1 causes the control signal DX to be high; during the second sub-time period, the low level of the second pulse width modulation signal PWM2 causes the control signal DX to be high; and during the third sub-time period, the low level of the third pulse width modulation signal PWM3 causes the control signal DX to be high. In this example, if the driver only drives three LEDs, the total time of the cycle is the sum of the three sub-time periods, that is, the time of a single cycle is divided into three sub-time periods, and the effective logic level of each pulse width modulation signal is allocated in a corresponding sub-time period. It is also worth noting that the parallel branch will be turned on whenever the control signal DX is high.

[0159] See Figure 11In an optional example, the first bypass unit SH1 includes a Zener diode SR and a resistor RL connected in series between the power input terminal VCC and the so-called potential reference terminal GND. The cathode or anode of the Zener diode SR is coupled to the power input terminal VCC through the resistor RL, and the anode or cathode of the Zener diode SR is coupled to the so-called potential reference terminal GND. The positions of the Zener diode SR and the resistor RL can be interchanged. If the resistor RL is omitted, the Zener diode SR can be directly coupled between the power input terminal VCC and the potential reference terminal GND. The first bypass unit SH1 is turned on only when the voltage drop of the drive device is not lower than a critical voltage that allows the Zener diode SR to reverse break down and conduct; otherwise, the first bypass unit SH1 is turned off. That is, the first bypass unit SH1 is turned on only when the voltage drop is not lower than the critical voltage that allows the Zener diode SR to reverse break down; when the voltage drop is lower than the critical voltage, the Zener diode SR is turned off, and the first bypass unit SH1 is turned off. In an optional example, the second bypass unit SH2 includes a Zener diode ZR. The cathode or anode of the Zener diode ZR is coupled to the power input terminal VCC, while the anode or cathode of the Zener diode is coupled to the potential reference terminal GND. The critical voltage for reverse breakdown of the Zener diode SR can be defined as the first threshold voltage, and the critical voltage for reverse breakdown of the Zener diode ZR can be defined as the second threshold voltage. According to curve 108 of the input current of the drive device, the second threshold voltage is required to be much greater than the first threshold voltage.

[0160] See Figure 11 In an optional example, the second bypass unit SH2 is turned on when the voltage drop between the power input terminal VCC and the potential reference terminal GND exceeds the second threshold voltage set by the second bypass unit SH2. Conversely, the second bypass unit SH2 is turned off when the voltage drop falls below the second threshold voltage set by the second bypass unit SH2. For example, the second threshold voltage can be a critical voltage at which the Zener diode ZR is reverse-broken. The second bypass unit SH2 is only turned on when the voltage drop is not lower than the critical voltage, causing the Zener diode ZR to be reverse-broken, and turned off when the voltage drop falls below the critical voltage, causing the Zener diode ZR to be turned off.

[0161] See Figure 11In an alternative embodiment where the second bypass unit SH2 replaces the Zener diode ZR, a voltage comparator can be used. The voltage comparator compares the voltage drop between the power input terminal VCC and the potential reference terminal GND with a second voltage, and connects a switch between the power input terminal VCC and the potential reference terminal GND, with the switch controlled by the comparator. When the voltage drop between the power input terminal VCC and the potential reference terminal GND exceeds the second voltage set by the second bypass unit SH2, the comparison result of the voltage comparator turns on the switch, causing the second bypass unit SH2 to conduct. Conversely, when the voltage drop between the power input terminal VCC and the potential reference terminal GND is lower than the second voltage set by the second bypass unit SH2, the comparison result of the voltage comparator turns off the switch, causing the second bypass unit SH2 to turn off. An embodiment using a voltage comparator is not shown in the figures. The second voltage used by the voltage comparator can be the same as the aforementioned second threshold voltage, and the switch is preferably connected in series with a component with a large resistance value, such as a resistor, between the power input terminal and the potential reference terminal.

[0162] See Figure 11 In an alternative embodiment, where the first bypass unit SH1 replaces the Zener diode SR, a voltage comparator can be used, for example. The voltage comparator compares the voltage drop between the power input terminal VCC and the potential reference terminal GND with a first voltage. A switching switch, controlled by the comparator, is connected between the power input terminal VCC and the potential reference terminal GND. When the voltage drop between the power input terminal VCC and the potential reference terminal GND exceeds the first voltage set for the first bypass unit SH1, the voltage comparator's comparison result turns on the switching switch, causing the first bypass unit SH1 to conduct. Conversely, when the voltage drop between the power input terminal VCC and the potential reference terminal GND is lower than the first voltage set for the first bypass unit SH1, the voltage comparator's comparison result turns off the switching switch, causing the first bypass unit SH1 to turn off. Embodiments using a voltage comparator are not shown in the figures. The first voltage used by the voltage comparator can be the same as the aforementioned first threshold voltage, and the switching switch is preferably connected in series with a component with a large resistance value, such as a resistor and a Zener diode, between the power input terminal and the potential reference terminal.

[0163] See Figure 11In an alternative example, the first bypass unit SH1 can be configured as follows: a resistor RL, a Zener diode ZR, and a current source (not shown in the figure) are connected in series between the so-called power input terminal VCC and the potential reference terminal GND of the drive unit. The first bypass unit SH1 is only turned on when the voltage drop across the drive unit is not lower than a critical voltage at which the Zener diode SR can be reverse-biased and broken down; otherwise, the first bypass unit SH1 is turned off. This is equivalent to adding another current source in series with the resistor RL and the Zener diode ZR in the example shown in the figure.

[0164] See Figure 11 In an alternative example, the first bypass unit SH1 can be configured as follows: a resistor RL, a Zener diode ZR, and a junction field-effect transistor (JFET, not shown in the figure) are connected in series between the so-called power input terminal VCC and the potential reference terminal GND of the drive device. The Zener diode SR and resistor RL are connected in series between the first terminal of the JFET and the power input terminal VCC. The control terminal of the JFET is coupled to the potential reference terminal GND, and the second terminal of the JFET is coupled to the potential reference terminal GND through another clamping resistor. This is equivalent to adding another JFET in series with resistor RL and Zener diode ZR as shown in the example. The first and second terminals of the JFET can be either drain and source, or source and drain, respectively. The first bypass unit SH1 is turned on when the voltage drop of the drive device is not lower than the critical voltage causing the Zener diode SR to reverse break down; when the voltage drop is lower than the critical voltage, the Zener diode SR is turned off, and the first bypass unit SH1 is turned off. In other words, besides the example shown in the figure, there are many other possible topologies for the first and second bypass units. However, the illustrated topology is relatively simple and cost-effective, and is a preferred embodiment, but not the only one. For example, the above text introduced various examples of the voltage regulator circuit included in the second bypass unit and various examples of the first bypass unit.

[0165] See Figure 11 In the optional examples, combined Figure 3Explanation: Suppose N drive devices 100 are connected in series between the positive terminal VP and the negative terminal VN of an external power supply. The voltage drop across the first drive device 100 is DIV1, the voltage drop across the second drive device 100 is DIV2, and so on, up to the so-called Nth drive device 100, whose voltage drop is DIVN. If the voltage of the external power supply is relatively stable and the characteristics of each drive device are consistent, the voltage differences between DIV1, DIV2, ... DIVN are very small and will not affect the normal operation of the drive device 100. However, once the voltage of the external power supply increases slightly, and there are differences among the drive devices, the voltage differences between DIV1, DIV2, ... DIVN will increase, negatively affecting the normal operation of the drive device 100, and these differences are inherent.

[0166] See Figure 11 In the optional examples, combined Figure 3 Explanation: The sum of the voltage drops across the drive units 100 is equal to the voltage of the external power supply. Expressed functionally, the sum of voltage drops DIV1 + DIV2 + ... + DIVN equals the supply voltage of the external power supply. Even slight increases or decreases in the power supply ripple can cause significant voltage differences between the series of voltage drops DIV1, DIV2, ..., DIVN. For example, voltage drop DIV2 might be much larger than voltage drop DIV1, or voltage drop DIVN might be much smaller than voltage drop DIV1. Essentially, the power supply voltage is not evenly distributed among the drive units 100, and this voltage distribution is highly random and unpredictable. Drive units 100 with excessively large voltage drops are often in an overvoltage state, resulting in high power consumption and heat generation. Drive units 100 with excessively small voltage drops may be in an undervoltage state, leading to malfunctions. Generally, drive units 100 in an overvoltage state will have their lifespan prematurely ended, rendering the entire series of drive units 100 unusable. The reason for the above drawbacks is that the increased voltage caused by slight or large changes in the power supply always accumulates at one or a few drive devices.

[0167] See Figure 11 In the optional examples, combined Figure 3Explanation: The first bypass unit SH1 adaptively increases its current when the drive current IS set by the drive device 100 deviates from its setting, resulting in a smaller current and relatively low power consumption and heat generation of the constant current unit. In this case, the first bypass unit SH1 increasing its current is equivalent to raising the voltage drop of the drive device 100 itself through its internal resistor. Conversely, the first bypass unit SH1 adaptively decreases its current when the drive current IS set by the drive device 100 deviates from its setting, resulting in a larger current and relatively high power consumption and heat generation of the constant current unit. In this case, the first bypass unit SH1 decreasing its current is equivalent to lowering the voltage drop of the drive device 100 itself through its internal resistor. Drive devices that originally had low power consumption and low heat generation can increase their power consumption by increasing the voltage drop, while drive devices that originally had high power consumption and high heat generation can decrease their power consumption by decreasing the voltage drop. This adaptive adjustment of current and voltage allows for a more balanced distribution of the power supply voltage to the series-connected drive devices. The voltage increase caused by slight or significant changes in the power supply cannot be concentrated at one or a few drive devices. The power supply voltage is reasonably distributed to each drive device, addressing concerns about potential large voltage differences between DIV1, DIV2, ... DIVN. This prevents a few drive devices from becoming concentrated heat sources, distributing heat evenly across all drive devices. The aforementioned internal resistance is, for example, resistor RL. In some cases, Zener diodes and Zener diodes are considered Zener diode elements; in this case, Zener diode SR can be called the first Zener diode, and Zener diode ZR can be called the second Zener diode. Drive devices with smaller drive currents increase the current of the first bypass unit, while drive devices with larger drive currents decrease the current of the first bypass unit. In other words, the current of the first bypass unit in a drive device with a smaller drive current is slightly larger than that in a drive device with a larger drive current. That is, when there is a mismatch between the drive current set by any drive device and the drive current set by other drive devices, the first bypass unit of that drive device adaptively adjusts the magnitude of the current flowing through it.

[0168] See Figure 8In an optional example, the first threshold voltage is represented by the voltage value V1 corresponding to the inflection point N1, and the second threshold voltage is represented by the voltage value V2 corresponding to the inflection point N2. When the voltage drop is not lower than the first threshold voltage set by the first bypass unit, the first bypass unit SH1 is turned on and the drive device enters the first operating mode, at which time the so-called constant current unit CS1 is activated. For example, the drive device uses a conventional voltage detector to compare the magnitude of the voltage drop and the first threshold voltage, and the so-called constant current unit CS1 is activated only when the voltage drop is not lower than the first threshold voltage. If the voltage drop is lower than the first threshold voltage set by the first bypass unit SH1, the first bypass unit SH1 is turned off and the drive device enters the second operating mode, at which time the constant current unit CS1 is disabled. For example, the drive device can use a conventional voltage detector to compare the magnitude of the drive device voltage drop and the first threshold voltage, and the so-called constant current unit CS1 is not activated when the voltage drop is lower than the first threshold voltage. The left side of the voltage value V1 represents the second operating mode, and the right side represents the first operating mode.

[0169] See Figure 8 In an optional example, a solution is provided for a voltage drop that causes the drive to malfunction and potentially fail to operate properly. When the drive enters the second operating mode, both the constant current unit CS1 and the first bypass unit SH1 are shut down, forcing capacitor CZ to charge and increase the voltage drop to allow the drive to enter the first operating mode. However, the drive quickly returns to the second operating mode due to the rapid drop in voltage, falling below the first threshold voltage. This cycle alternates between the second and first operating modes. This cycle is entirely caused by insufficient voltage drop. Only when the voltage drop rises to a level not lower than the first threshold voltage will this cycle be resolved, for example, by raising the power supply voltage level to resolve the cycle. Charging the drive's local capacitor cannot resolve this cycle, but the charging behavior of the drive's local capacitor ensures that the drive does not crash and remains in a low-voltage operating state.

[0170] See Figure 8In an optional example, when the voltage drop is not lower than the second threshold voltage set by the second bypass unit SH2 (e.g., not lower than the voltage value V2 corresponding to the inflection point N2), the drive device enters the third operating mode, and at this time, both the so-called first bypass unit SH1 and the second bypass unit SH2 will be turned on. Obviously, the second threshold voltage is significantly greater than the first threshold voltage. The left side of voltage value V2 represents the first operating mode, and the right side represents the third operating mode. For example, the drive device can use a conventional voltage detector to compare the voltage drop with the first and second threshold voltages. When the voltage drop is lower than voltage value V1, the drive device enters the second operating mode; when the voltage drop is not lower than voltage value V1 but is lower than voltage value V2, the drive device enters the first operating mode; when the voltage drop is not lower than voltage value V2, the drive device will directly enter the third operating mode. The drive device 100 mainly includes the above three operating modes. Note that in the second operating mode, the input current or output current of the drive device will not drop sharply because the drive device also has a capacitor, such as capacitor CZ, connected between the power input terminal and the potential reference terminal. When the drive unit enters the second operating mode, these capacitors provide power to ensure the drive unit remains powered and still provides a small current. For example, capacitor CZ can still power the data transmission module, pulse width modulation module, and even other functional modules of the drive unit. Although the constant current unit is not enabled and the first bypass unit is turned off, the other functions of the drive unit are unaffected. This avoids current or communication interruptions in the multi-stage drive unit link because capacitor CZ still supplies power to the drive unit. Imagine if a drive unit loses power and no current flows, creating a so-called current interruption; the entire link would be shut down. The input and output current curve 108 in the figure drops slightly in the second operating mode, but not to a very low level, such as near zero. The drive unit may switch between the three modes or operate in only one of the three modes. Therefore, the first bypass unit is essential for the drive unit, but the second bypass unit is optional and can be omitted; and the first operating mode is essential for the drive unit, but the second and third operating modes can be omitted.

[0171] See Figure 8In an optional example, under the first operating mode, i.e., the V1-V2 range, when the drive current IS set by any drive device differs from that set by other drive devices, the so-called first bypass unit SH1 of that drive device adjusts its own current while also adjusting the voltage drop value of that drive device. This ensures that the input current flowing into each of the different drive devices is equal, and clamps the voltage drops of the different drive devices with different drive currents to different voltage values. Any designated drive device 100 can be assumed to have three different drive current IS values: the first is a larger drive current IS, the second is a smaller drive current IS, and the third is a smaller drive current IS. In the first case, because the drive current is larger, the first bypass unit SH1 of the designated drive device 100 adjusts its own current to a smaller value; in the second case, because the drive current is moderate, the first bypass unit SH1 of the designated drive device 100 adjusts its own current to a moderate value; and in the third case, because the drive current is smaller, the first bypass unit SH1 of the drive device adjusts its own current to a larger value. In the first case, the current of the first bypass unit SH1 is small, so the designated drive device 100 operates at voltage VX. In the second case, the current of the first bypass unit SH1 is moderate, so the designated drive device 100 operates at voltage VY. In the third case, the current of the first bypass unit SH1 is large, so the designated drive device 100 operates at voltage VZ. In all three cases, the operating voltage is within the voltage range V1-V2, where VZ is greater than VY and VY is greater than VX. It is evident that the first bypass unit SH1 of the designated drive device 100, while regulating its own current, also simultaneously adjusts the voltage drop of the designated drive device 100. The rule is: the larger the drive current, the smaller the voltage drop; the smaller the drive current, the larger the voltage drop. In other words, the voltage drop of a drive device with a larger drive current is lower than that of a drive device with a smaller drive current.

[0172] See Figure 8In the optional example, under the first operating mode, i.e., the V1-V2 range, several different drive devices are compared in the series-connected multi-stage drive. For example, it can be assumed that the drive current IS of the column head drive device 100, a certain intermediate drive device 100, and the column tail drive device 100 are different: specifically, the drive current IS of the first drive device 100 is the largest, the drive current IS of the intermediate drive device 100 is the second largest, and the drive current IS of the column tail drive device 100 is the smallest. The first bypass unit SH1 of the column head drive device 100 has the smallest current and the voltage drop of the column head drive device 100 is the smallest. The first bypass unit SH1 of the intermediate drive device 100 has a medium current and the voltage drop of the intermediate drive device 100 is a medium voltage drop. The first bypass unit SH1 of the column tail drive device 100 has the largest current and the voltage drop of the column tail drive device 100 is the largest. This ensures that the input current flowing into these three drive devices as examples is equal, and their voltage drops are also clamped to different voltage values. Note that, in addition to the drive devices used as examples, in multi-stage drive devices: if the drive current set by any drive device differs from the drive current set by the remaining drive devices, the first bypass unit of that drive device will adjust the current flowing through it to ensure that the input current flowing into each different drive device is equal. At the same time, it will also adjust the voltage drop of that drive device to clamp the voltage drops of different drive devices with different drive currents to different voltage values.

[0173] See Figure 7 In the optional example, under the first operating mode (V1-V2 range), it is assumed that the ideal condition for the drive device is that the drive current IS is equal to the desired current value. However, in reality, the drive current IS deviates from the desired value in various ways. Typically, the drive current is either smaller or larger than the desired value, indicating a mismatch. It should be noted that the specific values ​​listed for the drive current or desired current value in the context are merely illustrative examples and do not constitute a limitation; the drive current or desired current value can take any reasonable value other than the listed specific values.

[0174] See Figure 7In an optional example, if the drive current IS of the first drive device 100 is the largest and its actual value has deviated from the expected current value, its first bypass unit SH1 current is the smallest. Meanwhile, for example, if the drive current IS of the tail drive device 100 is the smallest and its actual value has deviated from the expected current value, its first bypass unit SH1 current is the largest. For example, in the drive device chain, it can be assumed that the head drive device 100 deviates from the design rules, resulting in a drive current IS of 13mA; for example, it can be assumed that a middle drive device 100 deviates from the design rules, resulting in a drive current IS of 12mA; and for example, it can be assumed that the tail drive device 100 deviates from the design rules, resulting in a drive current IS of 10mA. Undoubtedly, there is a drive current mismatch between the drive current IS of the head drive device 100 and the drive currents of the middle and tail drive devices 100, even though they should ideally have the same expected current value, such as 12.5mA. The first drive unit has the largest actual drive current, and its actual drive current has deviated from the expected current value. The tail drive unit has the smallest actual drive current, and its actual drive current has also deviated from the expected current value. In essence, the first bypass unit SH1 of the first drive unit has the smallest current, and the first bypass unit SH1 of the tail drive unit has the largest current.

[0175] See Figure 12In an optional example, the first bypass unit SH1 includes a three-terminal adjustable shunt reference source TL and a resistor RL connected in series between the power input terminal VCC and the so-called potential reference terminal GND. For example, the cathode or negative terminal of the three-terminal adjustable shunt reference source TL can be coupled to the power input terminal VCC via the resistor RL, and the anode or positive terminal of the three-terminal adjustable shunt reference source TL can be coupled to the so-called potential reference terminal GND. It should also be noted that the positions of the three-terminal adjustable shunt reference source TL and the resistor RL can be interchanged. A specified voltage or preset voltage can be input to the voltage reference terminal of the three-terminal adjustable shunt reference source TL, i.e., the REF terminal. This specified voltage or preset voltage can be provided by a bandgap reference source integrated within the drive device. Typically, the three-terminal adjustable shunt reference source TL is an integrated circuit rather than a discrete device like a Zener diode; functionally, it is nearly equivalent to an adjustable Zener diode. Terms such as adjustable shunt voltage reference, adjustable precision parallel regulator, programmable reference circuit, three-terminal programmable parallel regulator, or programmable parallel voltage reference are all used to describe the aforementioned three-terminal adjustable shunt voltage reference (TL), although the naming rules and conventions differ slightly. The cathode (K), anode (A), and reference terminal (REF) are the three interface terminals of the three-terminal adjustable shunt voltage reference. The reference terminal (REF) is also called the voltage reference terminal or voltage reference terminal. A three-terminal adjustable shunt voltage reference can be designed as a standalone device or integrated into a driver chip as a sub-functional module of the driver chip.

[0176] See Figure 12In an optional example, the first bypass unit SH1 is turned on when the voltage drop between the power input terminal VCC and the potential reference terminal GND is not lower than the first threshold voltage set by the first bypass unit SH1. Conversely, the first bypass unit SH1 is turned off when the voltage drop is lower than the first threshold voltage set by the first bypass unit SH1. The first threshold voltage can be the minimum operating voltage required for the three-terminal adjustable shunt reference source TL to conduct. The first bypass unit SH1 is turned on only when the voltage drop is not lower than the minimum operating voltage sufficient for the three-terminal adjustable shunt reference source TL to conduct; when the voltage drop is lower than the minimum operating voltage, the three-terminal adjustable shunt reference source TL is turned off and the first bypass unit SH1 is turned off. In other words, the first threshold voltage is determined by the minimum operating voltage required for the three-terminal adjustable shunt reference source to conduct. The minimum operating voltage is the lowest voltage value required for the three-terminal adjustable shunt reference source to conduct and operate normally. The voltage drop must not be lower than this minimum voltage value for current to flow in the first bypass unit and the three-terminal adjustable shunt reference source; if the voltage drop is lower than this minimum voltage value, no current can flow in the first bypass unit and the three-terminal adjustable shunt reference source. The minimum operating voltage is also called the lower limit voltage value required for the three-terminal adjustable shunt reference source to conduct and operate normally. The second bypass unit SH2 can also essentially use a device like a three-terminal adjustable shunt reference source as a substitute for a Zener diode. For example, when setting the second threshold voltage for the second bypass unit, the second threshold voltage can be set to be greater than the first threshold voltage. The second threshold voltage is determined by the minimum operating voltage required for the three-terminal adjustable shunt reference source of the second bypass unit to conduct. This is an optional embodiment; of course, the second bypass unit can still use a Zener diode or a voltage comparator, etc.

[0177] The foregoing description and accompanying drawings have provided typical embodiments of specific structures for specific implementations. The above invention presents preferred embodiments, but these are not intended to be limiting. Various changes and modifications will undoubtedly be apparent to those skilled in the art after reading the foregoing description. Therefore, the appended claims should be considered as covering all changes and modifications that encompass the true intent and scope of the invention. Any and all equivalent scope and content within the scope of the claims should be considered to still fall within the intent and scope of the invention.

Claims

1. A driving device, characterized in that, include: Power input terminal and potential reference terminal; A constant current unit that can provide drive current to the load to implement constant current drive for the load; A first bypass unit connected between the power input terminal and the potential reference terminal; The constant current unit and the first bypass unit are connected in parallel. When multiple drive devices are connected in series, the first bypass unit in a drive device with a larger drive current has a smaller current, and the first bypass unit in a drive device with a smaller drive current has a larger current. When there is a mismatch between the drive current set by any drive device and the drive current set by the remaining drive devices, the first bypass unit of any drive device adaptively adjusts the magnitude of the current flowing through itself to ensure that the input current of any drive device is equal to that of the other drive devices.

2. The driving device according to claim 1, characterized in that: It also includes a data transmission module and a pulse width modulation module; The data transmission module is used to receive communication data; The pulse width modulation module generates a pulse width modulation signal based on the duty cycle information contained in the communication data. The on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

3. The driving device according to claim 1, characterized in that: It also includes a data transmission module, which is used to forward communication data; Multi-stage drive units receive communication data in a cascaded manner: after receiving communication data, each drive unit extracts the communication data belonging to its own stage and forwards the remaining communication data to the next stage connected to it in the cascade.

4. The driving device according to claim 1, characterized in that: The first bypass unit of any driving device, while adjusting its own current, also synchronously adjusts the voltage drop between the power input terminal and the potential reference terminal of any driving device: The voltage drop of different driving devices with mismatched driving currents is clamped to different voltage values.

5. The driving device according to claim 1, characterized in that: A capacitor is connected between the power input terminal and the potential reference terminal.

6. The driving device according to claim 1, characterized in that: The mechanisms that cause the mismatch include at least: The manufacturing process of the drive unit leads to manufacturing differences between different drive units; or Different drive units operate at different temperatures.

7. The driving device according to claim 1, characterized in that: When the voltage drop between the power input terminal and the potential reference terminal of the drive device is not lower than the first threshold voltage set by the first bypass unit: the first bypass unit is turned on; otherwise, the first bypass unit is turned off.

8. The driving device according to claim 1, characterized in that: It also includes a second bypass unit connected between the power input terminal and the potential reference terminal; When the voltage drop between the power input terminal and the potential reference terminal of the drive device is not lower than the second threshold voltage set by the second bypass unit: the second bypass unit is turned on; otherwise, the second bypass unit is turned off.

9. The driving device according to claim 7, characterized in that: The first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input terminal and the potential reference terminal; the first threshold voltage is determined by the minimum operating voltage required for the three-terminal adjustable shunt reference source to be turned on.

10. The driving device according to claim 8, characterized in that: The second bypass unit includes a Zener diode connected between the power input terminal and the potential reference terminal; The second threshold voltage is determined by the critical voltage at which the Zener diode breaks down in reverse.

11. A method for adjusting the current of a driving device, characterized in that: The drive unit includes: Power input terminal and potential reference terminal; A constant current unit that can provide drive current to the load; A first bypass unit connected between the power input terminal and the potential reference terminal; The constant current unit and the first bypass unit are connected in parallel. The method includes: Connect the multi-stage drive units in series; In a multi-stage drive system, the drive system with a larger drive current has a smaller current in the first bypass unit, and the drive system with a smaller drive current has a larger current in the first bypass unit. In this way, the first bypass unit of each drive device can adaptively adjust the current flowing through it so that the input current flowing into each drive device is equal.

12. The method according to claim 11, characterized in that: There is a voltage drop between the power input terminal and the potential reference terminal of each drive unit; The larger the driving current, the smaller the voltage drop of the driving device; The smaller the driving current, the greater the voltage drop of the driving device.

13. The method according to claim 11, characterized in that: When the voltage drop between the power input terminal and the potential reference terminal of the drive device is not lower than the first threshold voltage set by the first bypass unit: the first bypass unit is turned on; otherwise, the first bypass unit is turned off.

14. The method according to claim 11, characterized in that: It also includes a second bypass unit connected between the power input terminal and the potential reference terminal; When the voltage drop between the power input terminal and the potential reference terminal of the drive device is not lower than the second threshold voltage set by the second bypass unit: the second bypass unit is turned on; otherwise, the second bypass unit is turned off.

15. The method according to claim 13, characterized in that: The first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input terminal and the potential reference terminal, and a specified voltage is input to the voltage reference terminal of the three-terminal adjustable shunt reference source. The first threshold voltage is determined by the minimum operating voltage required when the three-terminal adjustable shunt reference source is turned on.

16. The method according to claim 14, characterized in that: The second bypass unit includes a Zener diode connected between the power input terminal and the potential reference terminal; The second threshold voltage is determined by the critical voltage at which the Zener diode breaks down in reverse.

17. The method according to claim 13, characterized in that: The drive unit also has a capacitor connected between the power input terminal and the potential reference terminal; When the voltage drop between the power input terminal and the potential reference terminal of any driving device falls below the first threshold voltage, the constant current unit and the first bypass unit of the driving device are turned off, and the capacitor of the driving device is charged.

18. The method according to claim 11, characterized in that: It also includes a data transmission module and a pulse width modulation module; The data transmission module is used to receive communication data; The pulse width modulation module generates a pulse width modulation signal based on the duty cycle information carried by the communication data. The on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

19. The method according to claim 11, characterized in that: It also includes a data transmission module, which is used to forward communication data; Multi-stage drive units receive communication data in a cascaded manner: after receiving communication data, each drive unit extracts the communication data belonging to its own stage and forwards the remaining communication data to the next stage connected to it in the cascade.

20. A driving device, characterized in that, include: Power input terminal and potential reference terminal; A constant current unit that can provide drive current to the load; A first bypass unit connected between the power input terminal and the potential reference terminal; The constant current unit and the first bypass unit are connected in parallel. In a series-connected multi-stage drive device, the drive device with a larger drive current has a smaller current in the first bypass unit, and the drive device with a smaller drive current has a larger current in the first bypass unit. In this way, the first bypass unit of each drive device can adaptively adjust the current flowing through it so that the input current flowing into each of all drive devices is equal.

21. The driving device according to claim 20, characterized in that: There is a voltage drop between the power input terminal and the potential reference terminal of the drive device. The larger the drive current, the smaller the voltage drop of the drive device, and the smaller the drive current, the larger the voltage drop of the drive device.

22. The driving device according to claim 20, characterized in that: When the voltage drop between the power input terminal and the potential reference terminal of the drive device is not lower than the first threshold voltage set by the first bypass unit: the first bypass unit is turned on; otherwise, the first bypass unit is turned off. The first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input terminal and the potential reference terminal; the first threshold voltage is determined by the minimum operating voltage required for the three-terminal adjustable shunt reference source to be turned on.

23. The driving device according to claim 22, characterized in that: The drive unit also has a capacitor connected between the power input terminal and the potential reference terminal; When the voltage drop between the power input terminal and the potential reference terminal of any driving device falls below the first threshold voltage, the constant current unit and the first bypass unit of the driving device are turned off, and the capacitor of the driving device is charged.

24. The driving device according to claim 20, characterized in that: It also includes a data transmission module and a pulse width modulation module; The data transmission module is used to receive communication data; The pulse width modulation module generates a pulse width modulation signal based on the duty cycle information carried by the communication data. The on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

25. The driving device according to claim 20, characterized in that: It also includes a data transmission module, which is used to forward communication data; Multi-stage drive units receive communication data in a cascaded manner: after receiving communication data, each drive unit extracts the communication data belonging to its own stage and forwards the remaining communication data to the next stage connected to it in the cascade.

26. A system, characterized in that, include: A multi-stage drive unit connected in series in terms of power supply; Each drive unit includes: Power input terminal and potential reference terminal; A constant current unit that can provide drive current to the load; The data transmission module receives and forwards communication data; A first bypass unit connected between the power input terminal and the potential reference terminal; The constant current unit and the first bypass unit are connected in parallel. The pulse width modulation module generates a pulse width modulation signal based on the duty cycle information contained in the communication data. The on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal. In this system: Multi-stage drive units receive communication data in a cascaded manner. After receiving the communication data, each drive unit extracts the communication data belonging to its own stage and forwards the remaining communication data to the next stage connected to it in the cascade. In a multi-stage drive system, the first bypass unit of a drive system with a larger drive current has a smaller current, and the first bypass unit of a drive system with a smaller drive current has a larger current. When there is a difference between the drive current set by any drive system and the drive current set by the other drive systems, the first bypass unit of any drive system adaptively adjusts the current flowing through itself, thereby ensuring that the input current flowing into each different drive system is equal.

27. The system according to claim 26, characterized in that: The first bypass unit of any driving device, while adjusting its own current, also synchronously adjusts the voltage drop between the power input terminal and the potential reference terminal of any driving device: The voltage drop of different driving devices with different driving currents is clamped to different voltage values.

28. The system according to claim 26, characterized in that: In each drive unit: The first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input terminal and the potential reference terminal; the first bypass unit is turned on when the voltage drop between the power input terminal and the potential reference terminal is not lower than the minimum operating voltage required for the three-terminal adjustable shunt reference source to conduct.

29. The system according to claim 26, characterized in that: In each drive unit: It also includes a second bypass unit connected between the power input terminal and the potential reference terminal. The second bypass unit includes a Zener diode connected between the power input terminal and the potential reference terminal. When the voltage drop between the power input terminal and the potential reference terminal is not lower than the critical voltage at which the Zener diode breaks down in reverse, the second bypass unit is turned on.

30. The system according to claim 26, characterized in that: Each drive unit also has a capacitor connected between the power input terminal and the potential reference terminal.

31. The system according to claim 26, characterized in that: The load includes a light-emitting diode.

32. The system according to claim 26, characterized in that: The driving device is designed in the form of a driving chip.

33. A driving device, characterized in that, include: There is a voltage drop between the power input terminal and the potential reference terminal. A constant current unit that can provide drive current to the load; A first bypass unit connected between the power input terminal and the potential reference terminal; The constant current unit and the first bypass unit are connected in parallel. When the voltage drop is not lower than the first threshold voltage set by the first bypass unit, the first bypass unit is turned on and the driving device enters the first working mode, at which time the constant current unit is activated; When the voltage drop is lower than the first threshold voltage set by the first bypass unit, the first bypass unit is turned off and the drive device enters the second working mode, at which time the constant current unit is disabled. Multi-stage drive units connected in series: Under the premise of the first working mode, the current of the first bypass unit in the driving device with a larger driving current is smaller, and the current of the first bypass unit in the driving device with a smaller driving current is larger. If the driving current set by any driving device is different from the driving current set by the remaining driving devices, the first bypass unit of any driving device will adjust the magnitude of the current flowing through itself to ensure that the input current of any driving device is equal to that of the other driving devices. At the same time, the voltage drop of any of the driving devices is adjusted, thereby clamping the voltage drops of different driving devices with different driving currents to different voltage values.

34. The driving device according to claim 33, characterized in that: It also includes a second bypass unit connected between the power input terminal and the potential reference terminal; When the voltage drop is not lower than the second threshold voltage set by the second bypass unit, both the first bypass unit and the second bypass unit are turned on, the drive device enters the third working mode, and the second threshold voltage is greater than the first threshold voltage.

35. The driving device according to claim 34, characterized in that: The first bypass unit includes a three-terminal adjustable shunt reference source and a resistor connected in series between the power input terminal and the potential reference terminal; the first threshold voltage is determined by the minimum operating voltage required for the three-terminal adjustable shunt reference source to turn on. The second bypass unit includes a Zener diode connected between the power input terminal and the potential reference terminal; The second threshold voltage is determined by the critical voltage at which the Zener diode breaks down in reverse.

36. The driving device according to claim 33, characterized in that: Each drive unit also has a capacitor connected between the power input terminal and the potential reference terminal; When the drive unit enters the second operating mode, the capacitor of the drive unit that has entered the second operating mode is charged.

37. The driving device according to claim 33, characterized in that: Each drive unit also includes a data transmission module and a pulse width modulation module; The data transmission module is used to receive communication data; The pulse width modulation module generates a pulse width modulation signal based on the duty cycle information carried by the communication data. The on or off state of the constant current unit connected in series with the load is controlled by the pulse width modulation signal.

38. The driving device according to claim 33, characterized in that: Each drive unit also includes a data transmission module, which is used to forward communication data; Multi-stage drive units receive communication data in a cascaded manner: after receiving communication data, each drive unit extracts the communication data belonging to its own stage and forwards the remaining communication data to the next stage connected to it in the cascade.

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