Programmable constant current and constant voltage source circuit and system

Abstract

The present invention discloses a programmable constant current and constant voltage source circuit and system, comprising an output switching module, a first and a second DAC modules, an IO port expansion module and a storage module. The first DAC module is connected to the upper control module via a first communication terminal, and has voltage and current output terminals connected to the output switching module, the voltage output terminal being connected to a follower unit and a gear selection unit. The second DAC module is connected to the upper control module via a second communication terminal, and the output terminal is connected to a signal amplification terminal and a first clamping unit. The IO port expansion module is connected to the second communication terminal, and is used to control the gear selection unit and the output switching module, and receive fault alarms from the first DAC module. The storage module is connected to the second communication terminal and is used to store error calibration data. The present invention expands the ports of the upper control module, and the constant voltage terminal utilizes voltage following, multi-gear selection and feedback regulation technology, while the constant current terminal utilizes dynamic clamping technology, which can meet the requirements of control accuracy, output stability and compatibility.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a programmable constant current and constant voltage source circuit and system. Background Art

[0002] Constant-current and constant-voltage source circuits are key modules in fields such as industrial control and precision instrumentation, providing stable current or voltage signals to loads. With the advancement of intelligent industry, traditional analog regulation solutions are being replaced by highly integrated digital solutions due to issues such as large temperature drift and poor flexibility. However, as application scenarios continue to expand, constant-current and constant-voltage source circuits still need further improvement in control accuracy, output stability, and compatibility to meet more stringent industrial needs and reliability requirements under complex operating conditions. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a programmable constant current and constant voltage source circuit and system that can meet the requirements of control accuracy, output stability and compatibility.

[0004] In one aspect, an embodiment of the present invention provides a programmable constant current and constant voltage source circuit, comprising:

[0005] Output switching module;

[0006] a first DAC module having an input terminal, a voltage output terminal, and a current output terminal; the first DAC module is connected to a first communication terminal, the first communication terminal is used to connect to a host control module; the voltage output terminal is connected to a follower unit and a gear selection unit; the output terminal of the follower unit is respectively connected to the voltage detection terminal of the first DAC module and the input terminal of the gear selection unit; the multiple output terminals of the gear selection unit are respectively connected to the first input terminal of the output switching module;

[0007] a second DAC module, connected to a second communication terminal, the second communication terminal being used to connect to the upper control module; an output terminal of the second DAC module being connected to a signal amplification unit and a first clamping unit, the first clamping unit being connected to the current output terminal and the output terminal of the signal amplification unit, respectively; and the current output terminal being connected to the second input terminal of the output switching module;

[0008] an IO port expansion module connected to the second communication terminal, wherein the multiple output terminals of the IO port expansion module are respectively connected to the control terminal of the gear selection unit and the control terminal of the output switching module, and one of the multiple input terminals of the IO port expansion module is connected to the fault alarm terminal of the first DAC module;

[0009] A storage module is connected to the second communication end, and the storage module is used to store error correction data.

[0010] According to some embodiments of the present invention, a first ESD protection unit is connected between the first DAC module and the first communication end.

[0011] According to some embodiments of the present invention, the first ESD protection unit includes a first TVS diode, a first current limiting diode, and a second current limiting diode, the first TVS diode is connected in series with the first current limiting diode, and the second current limiting diode is connected in parallel to both ends of the first TVS diode and the first current limiting diode.

[0012] According to some embodiments of the present invention, a second ESD protection unit is connected between the second DAC module and the second communication end, and the structure of the second ESD protection unit is the same as that of the first ESD protection unit.

[0013] According to some embodiments of the present invention, the first DAC module adopts an integrated circuit module of model AD5422.

[0014] According to some embodiments of the present invention, the output end of the follower unit is connected to a first TVS protection unit and a second clamping unit.

[0015] According to some embodiments of the present invention, the current output end of the first DAC module is further connected to a second TVS protection unit.

[0016] According to some embodiments of the present invention, the current output end of the first DAC module is further connected to a third clamping unit.

[0017] According to some embodiments of the present invention, the first communication terminal is a communication terminal based on the SPI protocol, and the second communication terminal is a communication terminal based on the I2C protocol.

[0018] On the other hand, an embodiment of the present invention provides a programmable constant current and constant voltage source system, including the above-mentioned programmable constant current and constant voltage source circuit.

[0019] The embodiments of the present invention have at least the following beneficial effects:

[0020] The first DAC module converts the signal of the upper control module into constant voltage output and constant current output, and has a fault alarm function, and realizes on-demand switching through the output switching module. The constant voltage output branch realizes impedance matching and voltage feedback adjustment through the follower unit, and realizes precise matching and stable output of the output voltage through the gear selection unit. The constant current output branch realizes precise and stable constant current output through the dynamic clamping circuit composed of the second DAC module, the signal amplification unit and the first clamping unit. The IO port expansion module expands the port of the upper control module, reduces the port requirement of the upper control module, and is compatible with different models of upper control modules. The storage module is used to store error correction data to facilitate error calibration of the upper control module and further improve control accuracy.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0023] Figure 1 This is a principle block diagram of a programmable constant current and constant voltage source system according to an embodiment of the present invention;

[0024] Figure 2 This is a circuit schematic diagram of a first DAC module of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0025] Figure 3 A circuit schematic diagram of a first ESD protection unit and a second ESD protection unit of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0026] Figure 4 1 is a circuit schematic diagram of a follower unit of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0027] Figure 5 This is a circuit schematic diagram of a gear selection unit of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0028] Figure 6 This is a circuit schematic diagram of an output switching module of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0029] Figure 7 This is a circuit schematic diagram of a second DAC module and a signal amplification unit of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0030] Figure 8This is a circuit schematic diagram of an IO port expansion module of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention;

[0031] Figure 9 This is a circuit schematic diagram of a storage module of a programmable constant current and constant voltage source circuit according to an embodiment of the present invention.

[0032] Reference numerals:

[0033] Upper control module 20, load circuit 30, output switching module 100, first DAC module 200, first communication terminal 201, follower unit 210, gear selection unit 220, first ESD protection unit 230, second DAC module 300, second communication terminal 301, signal amplification unit 310, first clamping unit 320, second ESD protection unit 330, IO port expansion module 400, storage module 500. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0035] In the description of the present invention, "several" means one or more, "multiple" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. The use of terms such as "first" and "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, words such as “setting”, “installation” and “connection” should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above words in the present invention based on the specific content of the technical solution.

[0037] Please refer to Figure 1This embodiment discloses a programmable constant current and constant voltage source system, including an upper control module 20 and a programmable constant current and constant voltage source circuit. The programmable constant current and constant voltage source circuit is connected to a load circuit 30, and the load power supply is connected to the feedback detection terminal of the upper control module 20 to realize closed-loop feedback control, thereby improving the control accuracy and stability of the output. According to different application scenarios, the upper control module 20 can adopt processors with different performances, such as a single-chip microcomputer. Taking into account the performance and interface differences of different processors, the programmable constant current and constant voltage source circuit is designed as an independent integrated module, and a communication terminal based on a universal protocol (such as the first communication terminal 201 and the second communication terminal 301 below) is configured to connect to the upper control module 20. Different upper control modules 20 can be configured according to the requirements of different application scenarios, which is conducive to improving the compatibility of the programmable constant current and constant voltage source circuit.

[0038] Please continue to refer to Figure 1 The programmable constant current and constant voltage power supply includes an output switching module 100, a first DAC module 200, a second DAC module 300, an IO port expansion module 400, and a storage module 500. DAC stands for Digital to Analog Converter. The first DAC module 200 has an input terminal, a voltage output terminal, and a current output terminal. The first DAC module 200 is connected to a first communication terminal 201, which is used to connect to the upper control module 20. The voltage output terminal is connected to a follower unit 210 and a gear selection unit 220. The output terminal of the follower unit 210 is respectively connected to the voltage detection terminal of the first DAC module 200 and the input terminal of the gear selection unit 220. The multiple output terminals of the gear selection unit 220 are respectively connected to the first input terminal of the output switching module 100. The second DAC module 300 is connected to a second communication terminal 301, which is used to connect to the upper control module 20. The output terminal of the second DAC module 300 is connected to a signal amplification unit 310 and a first clamping unit 320. The first clamping unit 320 is respectively connected to the current output terminal and the output terminal of the signal amplification unit 310. The current output terminal is connected to the second input terminal of the output switching module 100. The IO port expansion module 400 is connected to the second communication terminal 301. The multiple output terminals of the IO port expansion module 400 are respectively connected to the control terminal of the gear selection unit 220 and the control terminal of the output switching module 100. One of the multiple input terminals of the IO port expansion module 400 is connected to the fault alarm terminal of the first DAC module 200. The storage module 500 is connected to the second communication terminal 301 and is used to store error correction data.

[0039] The upper control module 20 usually adopts an integrated circuit module with logic processing capabilities, such as a single-chip microcomputer, whose output signal is a digital signal, which is converted into a corresponding analog signal, i.e., a voltage signal and a current signal, through the first DAC module 200. The voltage output end of the first DAC module 200 is connected to the follower unit 210. The follower unit 210 has the characteristics of high input impedance and low output impedance, which realizes impedance matching and electrical isolation of the front and rear stage circuits, ensuring that the output voltage is not affected by the change of the rear stage impedance, preventing mutual interference, and thus improving the stability of the output voltage. In addition, the output voltage of the follower unit 210 strictly follows the input voltage, and the voltage can be kept stable even if the load changes. The output end of the follower unit 210 is connected to the voltage detection end of the first DAC module 200, and the output voltage of the follower unit 210 can be sampled and detected, thereby realizing voltage feedback regulation of the first DAC module 200, which is conducive to improving the control accuracy and the stability of the voltage output. The gear selection unit 220 has multiple gear selection branches, each of which has an input end, an output end and a control end, which can realize the switching of different gears, so that the upper control module 20 can select the appropriate gear according to the load, thereby ensuring the voltage control accuracy.

[0040] The first DAC module 200 has a voltage output terminal and a current output terminal, which are directly or indirectly connected to the output switching module 100 to switch between a constant voltage output mode and a constant current output mode through the output switching module 100. For the current output terminal of the first DAC module 200, dynamic clamping technology is used to achieve precise control of the current output and stable output. Among them, the second DAC module 300, the signal amplification unit 310, and the first clamping unit 320 form a dynamic clamping branch. The second DAC module 300 is connected to the upper control module 20 via the second communication terminal 301 and converts the control signal of the upper control module 20 into an analog signal. After amplification by the signal amplification unit 310, it acts on the first clamping unit 320 to achieve dynamic adjustment of the clamping voltage value, which can maintain constant current output under different load conditions. In addition, during the constant current-constant voltage mode switching process, the first clamping unit 320 can also limit the voltage range of the error signal to prevent load current overflow or transient overshoot current, ensure the smoothness of the mode transition, and thus improve the stability of the output.

[0041] The first DAC module 200 is connected to the upper control module 20 via the first communication terminal 201, and the second DAC module 300 is connected to the upper control module 20 via the second communication terminal 301. The first communication terminal 201 and the second communication terminal 301 are both communication terminals based on a universal protocol. For example, the first communication terminal 201 is a communication terminal based on the SPI protocol, and the second communication terminal 301 is a communication terminal based on the I2C communication protocol. This simplifies the communication port of the upper control module 20 and facilitates compatibility with most logic processing modules on the market. In addition, the IO port expansion module 400 is connected to the upper control module 20 via the second communication terminal 301, realizing port expansion of the upper control module 20, so that the upper control module 20 can use the IO port expansion module 400 to control the multi-gear switching of the gear selection unit 220 and output switching of the output switching module 100. Furthermore, the fault alarm terminal of the first DAC module 200 is also connected to one of the multiple input terminals of the IO port expansion module 400. This allows the fault signal to be uploaded to the upper control module 20 via the IO port expansion module 400, thereby improving control reliability. The storage module 500 is connected to the upper control module 20 via the second communication terminal 301, allowing the upper control module 20 to calibrate the output signal based on the feedback detection signal from the load circuit 30 and the error correction data stored in the storage module 500, thereby improving the accuracy of the output signal control and the output stability.

[0042] In this way, the first DAC module 200 converts the signal of the upper control module 20 into constant voltage output and constant current output, and has a fault alarm function, and realizes on-demand switching through the output switching module 100. The constant voltage output branch realizes impedance matching and voltage feedback adjustment through the follower unit 210, and realizes precise matching and stable output of the output voltage through the gear selection unit 220. The constant current output branch realizes accurate and stable constant current output through the dynamic clamping circuit composed of the second DAC module 300, the signal amplification unit 310 and the first clamping unit 320. The IO port expansion module 400 expands the port of the upper control module 20, reduces the port requirements of the upper control module 20, and is compatible with different models of upper control modules 20. The storage module 500 is used to store error correction data to facilitate the upper control module 20 to perform error calibration and further improve control accuracy.

[0043] For example, please refer to Figure 2 , Figure 2The schematic diagram of the first DAC module 200 is shown in FIG. In this embodiment, the first DAC module 200 utilizes an AD5422 integrated circuit module (hereinafter referred to as the 5422 integrated module). The 5422 integrated module supports constant voltage and constant current modes, features 16-bit resolution, and provides high-precision current and voltage outputs. Its total unadjusted error (TUE) is as low as ±0.01% FSR (Full Scale Range). An internal 5V reference voltage source provides low output drift (current output ±3 ppm / °C, voltage output ±2 ppm / °C), improving the voltage's ability to resist temperature interference and adapting to various application scenarios. Furthermore, the output of the 5422 integrated module features short-circuit and open-circuit protection, ensuring stable operation in harsh industrial environments. The 5422 integrated module also incorporates diagnostic functionality that detects faults (such as overtemperature or abnormal voltage) in real time and issues alarms through corresponding pins, improving circuit reliability and maintenance efficiency.

[0044] Please refer to Figure 2 and Figure 3 In order to further improve the stable output performance under high-precision control, a first ESD protection unit 230 is connected between the first DAC module 200 and the first communication terminal 201, which can stabilize the communication signal between the first DAC module 200 and the upper control module 20, for example, suppress surge voltage, protect the first DAC module 200, prevent communication errors or chip lockup, and improve anti-interference capability.

[0045] The first ESD protection unit 230 includes a first TVS diode, a first current limiting diode and a second current limiting diode. The first TVS diode is connected in series with the first current limiting diode, and the second current limiting diode is connected in parallel to both ends of the first TVS diode and the first current limiting diode. Figure 3 As shown by the mark D61, the first current limiting diode is as follows Figure 3 As shown by the mark D62, the third current limiting diode is as follows Figure 3 As shown in the mark D63, the first TVS diode is used as the core protection device to form a series circuit with the first current limiting diode. At the same time, a parallel protection path is established through the second current limiting diode. Through the combination of multiple types of diodes, rapid voltage clamping can be achieved to protect precision devices (such as the first DAC module 200) from damage by ESD and transient voltage. It can also suppress interference signals and ensure the signal reliability between the upper control module 20 and the first DAC module 200, thereby ensuring the control accuracy and stability of the constant current or constant voltage output.

[0046] Please continue to refer to Figure 3Similar to the first DAC module 200, a second ESD protection unit 330 is connected between the second DAC module 300 and the second communication terminal 301. The structure of the second ESD protection unit 330 is the same as that of the first ESD protection unit 230. That is, the second ESD protection unit 330 and the first ESD protection unit 230 both adopt the same composite protection architecture. This not only enables the second ESD protection unit 330 to maintain the same protection characteristics as the first ESD protection unit 230, namely, by combining the fast voltage clamping capability of the TVS diode with the impedance characteristics of the current limiting diode to achieve nanosecond-level transient response and milliampere-level leakage current control, but also enables coordinated ESD protection control of the two communication terminals (the first communication terminal 201 and the second communication terminal 301), providing effective protection against electrostatic shock and limiting transient overvoltages at the communication terminals to within a safe threshold. This ensures the communication reliability between the first DAC module 200, the second DAC module 300, and the upper control module 20 at the hardware level, helps reduce circuit signal fluctuations, and thereby improves the circuit's control accuracy and output stability.

[0047] Please refer to Figure 4 , the follower unit 210 is a circuit unit based on an operational amplifier, such as Figure 4 The op amp is shown as U6A, wherein the non-inverting input of the op amp U6A is connected to the voltage output of the first DAC module 200, the output of the op amp U16A is connected to the inverting input to form feedback regulation, and the output of the op amp U16A is also connected to multiple inputs of the gear selection unit 220 and the voltage detection terminal of the first DAC module 200 (as shown by the node Vsen). In addition, the output of the follower unit 210 is connected to the first TVS protection unit and the second clamping unit, wherein the first TVS protection unit is shown as Figure 4 The second TVS diode shown by the mark D12, the second clamping unit is as shown in FIG. Figure 4 The diode D18 is shown in Figure 1. The cathode of diode D18 is connected to the output of op amp U16A, and the anode of diode D18 is connected to power supply node PP12V_IN. When the voltage output by op amp U16A exceeds the forward conduction voltage of diode D18, diode D18 conducts and clamps the output voltage of op amp U16A near the conduction voltage, improving output voltage stability. Diode D18 also prevents the voltage at power supply node PP12V_IN from being reversely transmitted to the output of op amp U16A, thereby protecting op amp U16A from reverse voltage damage.

[0048] Please refer to Figure 2 , the current output terminal of the first DAC module 200 is also connected to a second TVS protection unit, such as Figure 2The second TVS protection unit can absorb a large amount of transient energy in a short period of time and clamp the voltage within a safe range, thereby protecting the current output terminal of the first DAC module 200, reducing damage from transient voltage (such as spike pulses caused by inductive load switching), and achieving stable output under high-precision control.

[0049] Please continue to refer to Figure 2 , the current output terminal of the first DAC module 200 is further connected to a third clamping unit, such as Figure 2 The diode D17 is shown in FIG. The cathode of the diode D17 is connected to the current output terminal of the first DAC module 200, and the anode of the diode D17 is connected to the power supply node VCC. When the voltage at the current output terminal of the first DAC module 200 exceeds the forward conduction voltage of the diode D17, the diode D17 is turned on and clamps the voltage output by the first DAC module 200 to near the conduction voltage, thereby improving the output stability.

[0050] Please refer to Figure 5 , the figure shows a circuit schematic diagram of the gear selection unit 220. The gear selection unit 220 uses an electronic switch and has multiple gear selection branches. The control end of each gear selection branch is connected to the corresponding output end of the IO port expansion module 400, so as to switch different voltage gears according to the signal of the upper control module 20 to achieve precise control of the voltage. In order to achieve precise control of different gear voltages, different output ends of the gear selection unit 220 are connected to high-precision voltage divider resistors, such as the resistors marked R16, R17, and R18 in the figure. The resistance accuracy of the resistors reaches 0.1%, which can improve the control accuracy of the output voltage. The multiple output ends of the gear selection unit 220 are respectively connected to the first input end of the output switching module 100, such as Figure 6 As shown, the output switching module 100 uses a relay-type electronic device and is controlled by the MOS transistor Q1. The gate of the MOS transistor Q1 is connected to the IO port expansion module 400 (refer to Figure 8 ), and then controlled by the upper control module 20, so that the upper control module 20 can control the output switching module 100 to select the constant voltage output mode and the constant current output mode according to user needs.

[0051] Please refer to the following Figures 1 to 9 The programmable constant current and constant voltage source circuit of this embodiment is described in detail.

[0052] Please refer to Figure 1The programmable constant current and constant voltage source circuit is arranged as an independent integrated module on the same circuit board. The upper control module 20 is connected to the programmable constant current and constant voltage source circuit. The output end of the programmable constant current and constant voltage source circuit is connected to the load circuit 30. The load circuit 30 is connected to the feedback detection end of the upper control module 20, thereby realizing closed-loop feedback control between the upper control module 20, the programmable constant current and constant voltage source circuit and the load circuit 30. For example, the programmable constant current and constant voltage source circuit includes a storage module 500 (circuit diagram as shown in FIG. Figure 9 As shown), during operation, the upper control module 20 collects the feedback signal of the load circuit 30, and adjusts the control signal output to the programmable constant current and constant voltage source circuit according to the feedback signal and the error correction data stored in the storage module 500 to improve the control accuracy.

[0053] Please refer to Figure 1 、 Figure 2 and Figure 3 In order to be compatible with different upper control modules 20 to improve the versatility of the circuit, the programmable constant current and constant voltage source circuit is configured with a first communication terminal 201 and a second communication terminal 301 based on a universal protocol, such as the first communication terminal 201 is based on the SPI protocol, and the second communication terminal 301 is based on the I2C protocol. The first DAC module 200 is connected to the first communication terminal 201 to connect to the upper control module 20 through the first communication terminal 201. In the constant current and constant voltage source circuit, the voltage fluctuation of any node may cause fluctuations in the output voltage or output current. Therefore, this embodiment configures an ESD protection unit at the communication terminal of the upper control module 20 to reduce the impact of transient voltage on the circuit, thereby improving the stability of the output. Among them, please refer to Figure 3 The first communication terminal 201 is configured with a first ESD protection unit 230, and the second communication terminal 301 is configured with a second ESD protection unit 330. The first ESD protection unit 230 and the second ESD protection unit 330 both adopt the same composite protection architecture, that is, the first TVS diode is used as the core protection device, forming a series circuit with the first current limiting diode, and establishing a parallel protection path through the second current limiting diode to achieve fast clamping voltage, nanosecond transient response and milliampere leakage control, and at the same time form effective protection against electrostatic shock, improve the communication reliability between the upper control module 20, the first DAC module 200 and the second DAC module 300, which is beneficial to reduce the signal fluctuation of the circuit, thereby improving the control accuracy of the circuit and the stability of the output.

[0054] Please refer to Figure 2The first DAC module 200 uses an integrated circuit module model AD5422. The 5422 integrated module supports constant voltage mode and constant current mode, can provide high-precision current and voltage output, and has small output drift, and can provide a high stable output. In the constant voltage output mode, the first DAC module 200 outputs a high-precision voltage signal according to the signal of the upper control module 20, and the voltage signal is output to the follower unit 210 (the circuit schematic diagram is shown in FIG. Figure 4 As shown, follower unit 210 has high input impedance and low output impedance, enabling signal isolation between the preceding and following circuits and reducing interference from load circuit 30 on the input signal. Furthermore, the output signal of follower unit 210 strictly follows the input signal, ensuring control accuracy. The output terminal of follower unit 210 is connected to the voltage detection terminal of first DAC module 200, thereby enabling voltage feedback regulation of first DAC module 200, which helps improve control accuracy and output stability. The follower unit 210 uses the operational amplifier U16A as its working core, and configures a diode D18 and a second TVS diode D12 at the output end of the operational amplifier U16A. The cathode of the diode D18 is connected to the output end of the operational amplifier U16A, and the anode of the diode D18 is connected to the power supply node PP12V_IN. When the output voltage of the operational amplifier U16A exceeds the forward conduction voltage of the diode D18, the diode D18 is turned on, thereby clamping the output voltage of the operational amplifier U16A, which is beneficial to improving the output stability. The second TVS diode D12 can effectively protect against transient voltages (noise interference) and reduce voltage fluctuations. The diode D18 and the second TVS diode D12 can cooperate to reduce noise interference and improve the stability of the output voltage of the operational amplifier U16A. Furthermore, the output voltage of the operational amplifier U16A is input to the first DAC module 200 for feedback control to achieve constant voltage output of the first DAC module 200, which is beneficial to achieve high-precision control and improve output stability.

[0055] The output end of the follower unit 210 is connected to the gear selection unit 220. Figure 5 The electronic switch shown by the mark U5 in the middle, the gear selection unit 220 has multiple gear selection branches, the input ends of the multiple gear selection branches are connected to the output end of the follower unit 210, and the output ends of the multiple gear selection branches are respectively connected to corresponding voltage divider resistors, such as Figure 5The resistors marked R15, R16, R17, and R18 are high-precision resistors, i.e., the resistance error is ±0.1%, to achieve high-precision voltage control. The control ends of the multiple gear selection branches of the gear selection unit 220 are connected to the multiple output ends of the IO port expansion module 400. The multiple output ends of the gear selection unit 220 are all connected to the first input end of the output switching module 100. The output end of the output switching module 100 is connected to the load circuit 30, and the control end of the output switching module 100 is connected to the IO port expansion module 400. The upper control module 20 sends a control signal to the output switching module 100 through the IO port expansion module 400 according to actual application requirements to achieve control of the constant voltage output mode and the constant current output mode. In the constant voltage output mode, the upper control module 20 can send a control signal to the gear selection unit 220 through the IO port expansion module 400 according to the load resistance of the load circuit 30 to switch different gear branches, thereby achieving high-precision control of the constant voltage output.

[0056] In the constant current output mode, the current output terminal of the first DAC module 200 provides an output signal to the output switching module 100. In order to achieve high-precision control and stable output, the current output terminal of the first DAC module 200 is connected to the first clamping unit 320, such as Figure 2 The diode marked D14 is shown in FIG. 1 , and the first clamping unit 320 cooperates with the second DAC module 300 and the signal amplifying unit 310 to realize dynamic voltage clamping, wherein the upper control module 20 dynamically adjusts the control signal of the second DAC module 300 according to the load resistance of the load circuit 30. Please refer to FIG. Figure 2 and Figure 7 The second DAC module 300 performs digital-to-analog conversion on the control signal of the upper control module 20, and amplifies the signal through the signal amplification unit 310 to apply it to the first clamping unit 320, thereby controlling the voltage at the current output end of the first DAC module 200 within a reasonable range according to the load, which is beneficial to improving the control accuracy and output stability. Figure 7 The operational amplifier marked as U16B shown in the figure is used as the core, and a feedback adjustment network of resistors R26, R25 and capacitor C30 is configured at the inverting input end to achieve stable output of the amplified signal, thereby improving the control stability of the first clamping unit 320 and further improving the stability of the constant current output.

[0057] In addition, the current output end of the first DAC module 200 is also connected to a second TVS protection unit and a third clamping unit. The second TVS protection unit is as follows: Figure 2 The third TVS diode, indicated by D13, can reduce the damage caused by transient voltage and achieve stable output under high-precision control. Figure 2The diode D17 in FIG. 1 has its cathode connected to the current output terminal of the first DAC module 200 and its anode connected to the power supply node VCC. When the voltage at the current output terminal of the first DAC module 200 exceeds the forward conduction voltage of diode D17, diode D17 conducts, providing a clamping effect. The dynamic clamping of the first clamping unit 320, combined with the static clamping of the third clamping unit, can control the output voltage of the first DAC module 200 within a desired range. Combined with the second TVS protection unit, this reduces circuit noise interference, facilitating stable output under high-precision control.

[0058] It is worth mentioning that the 5422 integrated module also integrates diagnostic functions, which can detect faults in real time, such as overtemperature or abnormal voltage. Figure 2 and Figure 8 The node marked as FAULT sends a fault alarm signal to the IO port expansion module 400, and sends the signal to the upper control module 20 through the IO port expansion module 400, which is beneficial to improving circuit reliability and maintenance efficiency.

[0059] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A programmable constant current and constant voltage source circuit, characterized in that: include: Output switching module (100); A first DAC module (200) has an input terminal, a voltage output terminal, and a current output terminal. The first DAC module (200) is connected to a first communication terminal (201), the first communication terminal (201) is used to connect to an upper control module (20), the voltage output terminal is connected to a follower unit (210) and a gear selection unit (220), the output terminal of the follower unit (210) is respectively connected to the voltage detection terminal of the first DAC module (200) and the input terminal of the gear selection unit (220), the multiple output terminals of the gear selection unit (220) are respectively connected to the first input terminal of the output switching module (100), and the current output terminal is connected to the second input terminal of the output switching module (100); A second DAC module (300) is connected to a second communication terminal (301), the second communication terminal (301) being used to connect to the upper control module (20), an output terminal of the second DAC module (300) being connected to a signal amplification unit (310) and a first clamping unit (320), the first clamping unit (320) being connected to the current output terminal and the output terminal of the signal amplification unit (310), respectively; an IO port expansion module (400) connected to the second communication terminal (301), a plurality of output terminals of the IO port expansion module (400) being respectively connected to the control terminal of the gear selection unit (220) and the control terminal of the output switching module (100), and one of the plurality of input terminals of the IO port expansion module (400) being connected to the fault alarm terminal of the first DAC module (200); A storage module (500) is connected to the second communication terminal (301), and the storage module (500) is used to store error correction data.

2. The programmable constant current and constant voltage source circuit according to claim 1, characterized in that: A first ESD protection unit (230) is connected between the first DAC module (200) and the first communication terminal (201).

3. The programmable constant current and constant voltage source circuit according to claim 2, characterized in that: The first ESD protection unit (230) comprises a first TVS diode, a first current limiting diode and a second current limiting diode, the first TVS diode and the first current limiting diode are connected in series, and the second current limiting diode is connected in parallel to both ends of the first TVS diode and the first current limiting diode.

4. The programmable constant current and constant voltage source circuit according to claim 2 or 3, characterized in that: A second ESD protection unit (330) is connected between the second DAC module (300) and the second communication terminal (301), and the structure of the second ESD protection unit (330) is the same as that of the first ESD protection unit (230).

5. The programmable constant current and constant voltage source circuit according to claim 1, 2 or 3, characterized in that: The first DAC module (200) adopts an integrated circuit module of model AD5422.

6. The programmable constant current and constant voltage source circuit according to claim 1, 2 or 3, characterized in that: The output end of the follower unit (210) is connected to a first TVS protection unit and a second clamping unit.

7. The programmable constant current and constant voltage source circuit according to claim 1, wherein: The current output end of the first DAC module (200) is also connected to a second TVS protection unit.

8. The programmable constant current and constant voltage source circuit according to claim 1 or 7, characterized in that: The current output end of the first DAC module (200) is also connected to a third clamping unit.

9. The programmable constant current and constant voltage source circuit according to claim 1, wherein: The first communication terminal (201) is a communication terminal based on the SPI protocol, and the second communication terminal (301) is a communication terminal based on the I2C protocol.

10. A programmable constant current and constant voltage source system, characterized in that: The invention comprises a programmable constant current and constant voltage source circuit as claimed in any one of claims 1 to 9.

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