Programmable constant-current constant-voltage source circuit and system

Abstract

The invention discloses a programmable constant-current constant-voltage source circuit and system. The programmable constant-current constant-voltage source circuit comprises an output switching module, a first DAC module, a second DAC module, an IO port expansion module and a storage module. The first DAC module is connected with the upper control module through a first communication end and is provided with a voltage and current output end connected to the output switching module, the voltage output end is connected with the follower unit and the gear selection unit, the second DAC module is connected with the upper control module through a second communication end, and the output end is connected with the signal amplification end and the first clamping unit. The IO port expansion module is connected with the second communication end and used for controlling the gear selection unit and the output switching module and receiving a fault alarm of the first DAC module, and the storage module is connected with the second communication end and used for storing error calibration data. Port expansion is carried out on the upper control module, a constant voltage end utilizes voltage following, multi-gear selection and feedback regulation technologies, a constant current end utilizes a dynamic clamping technology, and the requirements in the aspects of control precision, output stability, compatibility and the like can be met.

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] The constant current and constant voltage source circuit is a key module in the fields of industrial control and precision instruments, used to provide a stable current or voltage signal to the load. With the development of industrial intelligence, traditional analog regulation solutions are gradually being replaced by highly integrated digital solutions due to problems such as large temperature drift and poor flexibility. However, with the continuous expansion of application scenarios, the constant current and constant voltage source circuit still needs to be further improved in terms of control accuracy, output stability, and compatibility to meet more stringent industrial needs and reliability requirements under complex working 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 proposes a programmable constant current and constant voltage source circuit and system, which can meet the requirements of control accuracy, output stability and compatibility.

[0004] On the one hand, an embodiment of the present invention provides a programmable constant current and constant voltage source circuit, comprising: Output switching module; 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, and the multiple output terminals of the gear selection unit are respectively connected to the first input terminal of the output switching module; A second DAC module is connected to a second communication terminal, the second communication terminal is used to connect to the upper control module, the output terminal of the second DAC module is connected to a signal amplification unit and a first clamping unit, the first clamping unit is respectively connected to the current output terminal and the output terminal of the signal amplification unit, and the current output terminal is connected to the second input terminal of the output switching module; an IO port expansion module connected to the second communication terminal, wherein a plurality of output terminals of the IO port expansion module are respectively connected to a control terminal of the gear selection unit and a control terminal of the output switching module, and one of a plurality of input terminals of the IO port expansion module is connected to a fault alarm terminal of the first DAC module; A storage module is connected to the second communication end, and the storage module is used to store error correction data.

[0005] According to some embodiments of the present invention, a first ESD protection unit is connected between the first DAC module and the first communication terminal.

[0006] 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.

[0007] According to some embodiments of the present invention, a second ESD protection unit is connected between the second DAC module and the second communication terminal, and the structure of the second ESD protection unit is the same as that of the first ESD protection unit.

[0008] According to some embodiments of the present invention, the first DAC module adopts an integrated circuit module of model AD5422.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] According to some embodiments of the present invention, the first communication end is a communication end based on the SPI protocol, and the second communication end is a communication end based on the I2C protocol.

[0013] 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.

[0014] The embodiments of the present invention have at least the following beneficial effects: 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 and reduces the port requirement of the upper control module to facilitate compatibility with different models of upper control modules. The storage module is used to store error correction data, which is convenient for the upper control module to perform error calibration and further improve the control accuracy.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 It is a principle block diagram of a programmable constant current and constant voltage source system according to an embodiment of the present invention; Figure 2 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; 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; Figure 4 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; Figure 5 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; Figure 6 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; Figure 7 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; Figure 8 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; Fig. 9 The circuit schematic diagram of the storage module of the programmable constant current and constant voltage source circuit according to an embodiment of the present invention.

[0017] Reference numerals: The upper control module 20, the load circuit 30, the output switching module 100, the first DAC module 200, the first communication terminal 201, the follower unit 210, the gear selection unit 220, the first ESD protection unit 230, the second DAC module 300, the second communication terminal 301, the signal amplification unit 310, the first clamping unit 320, the second ESD protection unit 330, the IO port expansion module 400, and the storage module 500. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which 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 only used to explain the present invention, and cannot be understood as limiting the present invention.

[0019] In the description of the present invention, "several" means one or more, "multiple" means more than two, greater than, less than, and exceeding are understood as not including the number itself, and "above", "below", and "within" are understood as including the number itself. If there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0020] 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 in combination with the specific content of the technical solution.

[0021] Please refer to Figure 1 , this 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 the 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. Among them, according to different application scenarios, the upper control module 20 can use 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 general 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 needs of different application scenarios, which is conducive to improving the compatibility of the programmable constant current and constant voltage source circuit.

[0022] Please continue to refer to Figure 1The programmable constant current and constant voltage power supply comprises 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 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. The second DAC module 300 is connected to a second communication terminal 301, and the second communication terminal 301 is used to connect to the upper control module 20. The output terminal of the second DAC module 300 is connected to the signal amplification unit 310 and the 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, and 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, and 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, and 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 the storage module 500 is used to store error correction data.

[0023] The upper control module 20 usually adopts an integrated circuit module with logic processing capabilities, such as a single-chip microcomputer, and its output signal is a digital signal, which is converted into a corresponding analog signal, i.e., a voltage signal and a current signal, by the first DAC module 200. The voltage output end of the first DAC module 200 is connected to the follower unit 210, and the follower unit 210 has the characteristics of high input impedance and low output impedance, so as to realize impedance matching and electrical isolation of the front and rear circuits, ensure that the output voltage is not affected by the change of the rear impedance, prevent mutual interference, and thus improve 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 the 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 control accuracy of the voltage.

[0024] The first DAC module 200 has a voltage output terminal and a current output terminal, and the voltage output terminal and the current output terminal are directly or indirectly connected to the output switching module 100 to realize the switching between the constant voltage output mode and the constant current output mode through the output switching module 100. For the current output terminal of the first DAC module 200, the dynamic clamping technology is used to realize the precise control of the current output and the 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 through the second communication terminal 301, and the control signal of the upper control module 20 is converted into an analog signal, which is amplified by the signal amplification unit 310 and acts on the first clamping unit 320 to realize the dynamic adjustment of the clamping voltage value, and the constant current output can be maintained 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 the load current from overflowing or the occurrence of transient overshoot current, and ensure the smoothness of the mode conversion, thereby improving the stability of the output.

[0025] 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 protocol based on the I2C communication terminal, which can simplify the communication port of the upper control module 20 and facilitate 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 to achieve port expansion of the upper control module 20, so that the upper control module 20 can perform multi-gear switching control on the gear selection unit 220 and output switching control on the output switching module 100 through the IO port expansion module 400. In addition, 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, and the fault signal can be uploaded to the upper control module 20 through the IO port expansion module 400 to improve the reliability of control. The storage module 500 is connected to the upper control module 20 through the second communication terminal 301, so that the upper control module 20 can calibrate the output signal according to the feedback detection signal of 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 stability of the output.

[0026] 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 accurate 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 requirement of the upper control module 20, so as to facilitate compatibility with different models of upper control modules 20, and the storage module 500 is used to store error correction data, which is convenient for the upper control module 20 to perform error calibration and further improve the control accuracy.

[0027] For example, please refer to Figure 2 , Figure 2, the circuit schematic diagram of the first DAC module 200 is shown in FIG. 1 . The first DAC module 200 of the present embodiment adopts an integrated circuit module of model AD5422 (hereinafter referred to as 5422 integrated module). The 5422 integrated module supports constant voltage mode and constant current mode, and has a 16-bit resolution, can provide high-precision current and voltage output, and the total unadjusted error (TUE) is as low as ±0.01% FSR (Full Scale Range). A 5V reference voltage source is integrated internally, and the output drift is small (current output ±3 ppm / °C, voltage output ±2 ppm / °C), which can improve the voltage's anti-interference ability to temperature and adapt to different application scenarios. In addition, the output end of the 5422 integrated module has short-circuit protection and open-circuit protection functions, which can ensure stable operation in harsh industrial environments. The 5422 integrated module also integrates a diagnostic function, which can detect faults (such as excessive temperature or abnormal voltage) in real time, and alarm through the corresponding pin, which is conducive to improving circuit reliability and maintenance efficiency.

[0028] 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 achieve the stability of the communication signal between the first DAC module 200 and the upper control module 20, such as suppressing surge voltage, protecting the first DAC module 200, preventing communication errors or chip lockup, and improving anti-interference ability.

[0029] The first ESD protection unit 230 includes a first TVS diode, a first current limiting diode and a second current limiting diode, wherein 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 in FIG. 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, and 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 voltages, and interference signals can also be suppressed to 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.

[0030] 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, so that not only the second ESD protection unit 330 maintains the protection characteristics consistent with the first ESD protection unit 230, that is, through the fast voltage clamping capability of the TVS diode combined with the impedance characteristics of the current limiting diode, nanosecond transient response and milliampere leakage current control are achieved, but also the ESD protection coordinated control of the two communication terminals (the first communication terminal 201 and the second communication terminal 301) can be achieved, so as to form an effective protection against electrostatic shock, and limit the transient overvoltage of the communication terminal to a safety threshold, so as to ensure the communication reliability between the first DAC module 200 and the second DAC module 300 and the upper control module 20 from the hardware level, which is conducive to reducing the signal fluctuation of the circuit, thereby improving the control accuracy of the circuit and the stability of the output.

[0031] 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 marked U6A in the figure is shown, wherein the non-inverting input terminal of the op amp U6A is connected to the voltage output terminal of the first DAC module 200, the output terminal of the op amp U16A is connected to the inverting input terminal to form feedback regulation, and the output terminal of the op amp U16A is also connected to multiple input terminals of the gear selection unit 220 and the voltage detection terminal of the first DAC module 200 (as shown by the node mark Vsen). In addition, the output terminal 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 as shown in FIG. Figure 4 The second TVS diode indicated by the mark D12 in FIG. 1 and the second clamping unit as shown in FIG. Figure 4 The diode marked D18 in FIG. The cathode of the diode D18 is connected to the output terminal of the operational amplifier U16A, and the anode of the diode D18 is connected to the power supply node PP12V_IN. When the voltage output by the operational amplifier U16A exceeds the forward conduction voltage of the diode D18, the diode D18 is turned on and clamps the voltage output by the operational amplifier U16A near the conduction voltage, thereby improving the stability of the output voltage. In addition, the diode D18 can also prevent the voltage of the power supply node PP12V_IN from being reversely transmitted to the output terminal of the operational amplifier U16A, thereby protecting the operational amplifier U16A from damage by reverse voltage.

[0032] 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 time and clamp the voltage within a safe range, thereby protecting the current output end of the first DAC module 200, reducing the damage of transient voltage (such as spike pulses caused by inductive load switching), and achieving stable output under high-precision control.

[0033] Please continue to refer to Figure 2 The current output terminal of the first DAC module 200 is also connected to a third clamping unit, such as Figure 2 The diode marked D17 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 the voltage output by the first DAC module 200 is clamped near the conduction voltage, thereby improving the output stability.

[0034] 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-dividing 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 a MOS tube Q1. The gate of the MOS tube 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.

[0035] 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.

[0036] 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, and 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. Fig. 9 As shown), when working, 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.

[0037] 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 fluctuation of 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 output stability. 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, and a series circuit is formed with the first current limiting diode, and a parallel protection path is established through the second current limiting diode to achieve fast clamping voltage, nanosecond transient response and milliampere leakage control, and at the same time, effective protection is formed against electrostatic shock, which improves 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.

[0038] Please refer to Figure 2The first DAC module 200 uses an integrated circuit module of 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 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 in FIG. 2 ), the follower unit 210 has high input impedance and low output impedance, which can realize signal isolation between the front and rear circuits, reduce the interference of the load circuit 30 on the input signal, and the output signal of the follower unit 210 strictly follows the input signal, which can ensure the control accuracy. The output end of the follower unit 210 is connected to the voltage detection end of the first DAC module 200, so as to realize the voltage feedback regulation of the first DAC module 200, which is conducive to improving the control accuracy and output stability. The follower unit 210 uses the operational amplifier U16A as the 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 voltage (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.

[0039] The output end of the follower unit 210 is connected to the gear selection unit 220. Figure 5 The electronic switch indicated by the mark U5 in the figure, the gear selection unit 220 has a plurality of gear selection branches, the input ends of the plurality of gear selection branches are all connected to the output end of the follower unit 210, and the output ends of the plurality of gear selection branches are respectively connected to corresponding voltage dividing resistors, such as Figure 5The resistors shown by the marks R15, R16, R17 and R18, wherein the resistors R16, R17 and R18 are high-precision resistors, that is, 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, and 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.

[0040] 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 in the figure, the first clamping unit 320 cooperates with the second DAC module 300 and the signal amplifying unit 310 to realize dynamic clamping of the voltage, 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 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, so as to control the voltage of the current output end of the first DAC module 200 within a reasonable range according to the load, which is beneficial to improve 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.

[0041] 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. Figure 2 The third TVS diode shown as D13 can reduce the damage of transient voltage and achieve stable output under high-precision control. Figure 2The diode marked D17 in the middle, the cathode of the diode D17 is connected to the current output end 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 end of the first DAC module 200 exceeds the forward conduction voltage of the diode D17, the diode D17 is turned on to play a clamping role. The dynamic clamping of the first clamping unit 320 cooperates with the static clamping of the third clamping unit to control the output voltage of the first DAC module 200 within the expected range, and cooperates with the second TVS protection unit to reduce the interference of circuit noise, which is conducive to achieving stable output under high-precision control.

[0042] 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.

[0043] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose 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) having an input terminal, a voltage output terminal and a current output terminal, the first DAC module (200) being connected to a first communication terminal (201), the first communication terminal (201) being used to connect to an upper control module (20), the voltage output terminal being connected to a follower unit (210) and a gear selection unit (220), the output terminal of the follower unit (210) being respectively connected to a voltage detection terminal of the first DAC module (200) and an input terminal of the gear selection unit (220), a plurality of output terminals of the gear selection unit (220) being respectively connected to a first input terminal of the output switching module (100), and the current output terminal being connected to a 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 respectively connected to the current output terminal and the output terminal of the signal amplification unit (310); 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 a control terminal of the gear selection unit (220) and a control terminal of the output switching module (100), and one of a plurality of input terminals of the IO port expansion module (400) being connected to a 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 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, characterized in that: 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, characterized in that: 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: It comprises a programmable constant current and constant voltage source circuit as described in any one of claims 1 to 9.

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