A DC output power supply

Abstract

The present invention discloses a DC output power supply, including an AC-DC switching power supply circuit, a power amplifier circuit, an MCU control circuit and a digital-to-analog conversion unit, wherein the power amplifier circuit includes a power amplifier, the output end of the AC-DC switching power supply circuit is connected to the power supply input end of the power amplifier, the control signal output end of the MCU control circuit is connected to the input end of the digital-to-analog conversion unit, the first output end of the digital-to-analog conversion unit is connected to the voltage control end of the power amplifier, and the second output end of the digital-to-analog conversion unit is connected to the current control end of the power amplifier. The circuit structure of the present invention is simple, and the output voltage and output current are adjusted by using a power amplifier circuit composed of a power amplifier with a small volume and weight in combination with an MCU control circuit, which can greatly reduce the volume and weight of the DC output power supply, so that the whole machine has the characteristics of small volume, light weight and easy mobility.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a direct current output power supply. Background Art

[0002] As electronic devices continue to appear in people's lives, they begin to play an increasingly important role in people's lives, and the speed of research and development of electronic devices is also getting faster and faster. In the process of daily testing, experiments, and research and development, electronic products and electronic equipment, from refrigerators, notebooks, and televisions to digital display vernier calipers and calculators, all require DC output power supplies to provide a stable and good test environment and power supply during the development and testing process. With the development of power supply technology, people have an increasing demand for light, fast, and easy-to-carry power supplies, and DC output power supplies are also constantly developing in the direction of miniaturization. Therefore, how to design a DC output power supply product that not only meets the needs of most test output voltages and output currents, but also meets the needs of miniaturization and lightweight is one of the research hotspots in the application of power supply technology today.

[0003] Existing DC output power supplies usually use a DC-DC switching power supply circuit (such as a Buck conversion circuit, a Boost conversion circuit or a Buck-Boost conversion circuit, etc.) combined with an MCU control circuit to achieve output voltage and output current regulation. The DC-DC switching power supply circuit used to regulate the output voltage and output current of the DC output power supply is large in size and has many components, resulting in a large overall size and heavy weight of the DC output power supply, which is not conducive to transportation and placement during use. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a direct current output power supply, comprising an AC-DC switching power supply circuit, a power amplifier circuit, an MCU control circuit and a digital-to-analog conversion unit, wherein the power amplifier circuit comprises a power amplifier, the output end of the AC-DC switching power supply circuit is connected to the power supply input end of the power amplifier, the control signal output end of the MCU control circuit is connected to the input end of the digital-to-analog conversion unit, the first output end of the digital-to-analog conversion unit is connected to the voltage control end of the power amplifier, and the second output end of the digital-to-analog conversion unit is connected to the current control end of the power amplifier.

[0005] Preferably, it also includes a current detection circuit for detecting the output current value of the power amplifier, the input end of the current detection circuit is connected to the output end of the power amplifier, and the current detection circuit is connected to the MCU control circuit.

[0006] Preferably, the current detection circuit includes a first resistor, a second resistor, a first electronic switch and a current monitoring chip, the output end of the power amplifier is respectively connected to the first end of the first resistor, the input end of the first electronic switch and the first input end of the current monitoring chip, the first end of the second resistor is respectively connected to the second end of the first resistor and the output end of the first electronic switch, the second end of the second resistor is connected to the second input end of the current monitoring chip, and the control end of the first electronic switch and the output end of the current monitoring chip are respectively connected to the MCU control circuit.

[0007] Preferably, the current detection circuit also includes a second electronic switch, which is a single-pole double-throw electronic switch, the output end of the power amplifier is connected to the first input end of the second electronic switch, the first end of the second resistor is connected to the second input end of the second electronic switch, the output end of the second electronic switch is connected to the first input end of the current monitoring chip, and the control end of the second electronic switch is connected to the MCU control circuit.

[0008] Preferably, the resistance value of the first resistor is greater than the resistance value of the second resistor.

[0009] Preferably, the model of the current monitoring chip is INA219BIDCNR.

[0010] Preferably, it also includes a first impedance matching circuit and a second impedance matching circuit, the first output end of the digital-to-analog conversion unit is connected to the voltage control end of the power amplifier through the first impedance matching circuit, and the second output end of the digital-to-analog conversion unit is connected to the current control end of the power amplifier through the second impedance matching circuit.

[0011] Preferably, it also includes a DC-DC switching power supply circuit and an LDO step-down circuit, the output end of the AC-DC switching power supply circuit is connected to the input end of the DC-DC switching power supply circuit, the output end of the DC-DC switching power supply circuit is connected to the input end of the LDO step-down circuit, and the output end of the LDO step-down circuit is connected to the MCU control circuit.

[0012] Preferably, it also includes an LCD display unit and a USB module, and the LCD display unit and the USB module are respectively connected to the MCU control circuit.

[0013] Preferably, the model of the power amplifier is OPA548T.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The circuit structure of the present invention is simple. The power amplifier circuit constructed by a power amplifier with small volume and weight is combined with an MCU control circuit to adjust the output voltage and output current, which can greatly reduce the volume and weight of the DC output power supply, so that the whole machine has the characteristics of small volume, light weight and easy mobility.

[0016] 2. The current detection circuit of the present invention sets a first resistor, a second resistor and a first electronic switch, connects the first resistor and the second resistor in series and then connects them in series between the output end of the power amplifier and the load, and combines the special wiring method of the first electronic switch with the first resistor and the second resistor. When the output current value of the power amplifier is small (such as the output current value is at the microampere level), a detection resistor with a larger resistance (that is, the first resistor and the second resistor are connected in series as the detection resistor) is combined with a current monitoring chip to detect the output current of the power amplifier, which greatly improves the current detection accuracy. When the output current value of the power amplifier is large (such as the output current is several amperes), a detection resistor with a smaller resistance (that is, only the second resistor is used as the detection resistor) is combined with a current monitoring chip to detect the output current of the power amplifier, avoiding the voltage drop across the detection resistor exceeding the voltage range of the current monitoring chip, thereby improving the measurement accuracy, thereby enabling the current detection circuit to have a wider current detection range and a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a circuit block diagram of the present invention;

[0018] Figure 2 is a circuit block diagram of a current detection circuit of the present invention;

[0019] Figure 3 It is a circuit schematic diagram of the MCU control circuit of the present invention;

[0020] Figure 4 It is a circuit principle diagram of the digital-to-analog conversion unit of the present invention;

[0021] Figure 5 is a circuit schematic diagram of a first impedance matching circuit of the present invention;

[0022] Figure 6 is a circuit schematic diagram of a second impedance matching circuit of the present invention;

[0023] Figure 7 It is a circuit principle diagram of the power amplifier circuit of the present invention;

[0024] Figure 8 is a circuit schematic diagram of a current detection circuit of the present invention;

[0025] Fig. 9 It is a circuit schematic diagram of the DC-DC switching power supply circuit of the present invention;

[0026] Fig.10 It is a circuit schematic diagram of the LDO step-down circuit of the present invention;

[0027] Fig.11 It is a circuit principle diagram of the USB module of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments; however, a DC output power supply of the present invention is not limited to the embodiments.

[0029] For examples, see Figure 1 As shown, a DC output power supply of the present invention includes an AC-DC switching power supply circuit 1, a power amplifier circuit 2, an MCU control circuit 3 and a digital-to-analog conversion unit 4, the power amplifier circuit 2 includes a power amplifier U7 (i.e., a power type operational amplifier), the output end of the AC-DC switching power supply circuit 1 is connected to the power supply input end of the power amplifier U7, the output end of the power amplifier U7 is connected to the load 12, the control signal output end of the MCU control circuit 3 is connected to the input end of the digital-to-analog conversion unit 4, the first output end of the digital-to-analog conversion unit 4 is connected to the voltage control end of the power amplifier U7 to adjust the output voltage of the power amplifier U7, and the second output end of the digital-to-analog conversion unit 4 is connected to the current control end of the power amplifier U7 to adjust the output current of the power amplifier U7.

[0030] Specifically, in this embodiment, the MCU control circuit 3 passes I 2 C communication is carried out with the digital-to-analog conversion unit 4 for signal transmission. The control signal output by the MCU control circuit 3 is a digital signal. The control signal output by the MCU control circuit 3 (the control signal is a control signal for adjusting the output voltage or output current of the power amplifier U7) is converted into an analog signal by the digital-to-analog conversion unit 4 and then sent to the voltage control end or current control end of the power amplifier U7.

[0031] See also Figure 1 As shown, in this embodiment, it also includes a current detection circuit 5 for detecting the output current value of the power amplifier U7. The input end of the current detection circuit 5 is connected to the output end of the power amplifier U7, and the output end of the current detection circuit 5 is connected to the load 12 (that is, the output end of the power amplifier U7 is connected to the load 12 through the current detection circuit 5). The current detection circuit 5 is connected to the MCU control circuit 3. The current detection circuit 5 feeds back the detection result to the MCU control circuit 3 and can receive the control signal sent by the MCU control circuit 3.

[0032] See also Figure 2As shown, in this embodiment, the current detection circuit 5 includes a first resistor R47, a second resistor R15, a first electronic switch 51 and a current monitoring chip U4, the output end of the power amplifier U7 is respectively connected to the first end of the first resistor R47, the input end of the first electronic switch 51 and the first input end of the current monitoring chip U4, the first end of the second resistor R15 is respectively connected to the second end of the first resistor R47 and the output end of the first electronic switch 51, the second end of the second resistor R15 is connected to the second input end of the current monitoring chip U4, the control end of the first electronic switch 51 and the output end of the current monitoring chip U4 are respectively connected to the MCU control circuit 3, and the first input end of the current monitoring chip U4 is specifically The negative input terminal of the current monitoring chip U4, the second input terminal of the current monitoring chip U4 is specifically the positive input terminal of the current monitoring chip U4, the second end of the second resistor R15 (that is, the output end of the DC output power supply) is connected to one end of the load 12 to power the load 12, and the other end of the load 12 is connected to the signal ground. The resistance values ​​of the first resistor R47 and the second resistor R15 are stored inside the current monitoring chip U4. The current monitoring chip U4 can detect the voltage across the second resistor R15 or the voltage between the first end of the first resistor R47 and the second end of the second resistor R15, and then calculate the output current value of the power amplifier U7 according to Ohm's law, and feed the detection result back to the MCU control circuit 3.

[0033] In this embodiment, when the output current value of the power amplifier U7 detected by the current detection circuit 5 is less than or equal to the preset threshold value, the MCU control circuit 3 sends a control signal to the control end of the first electronic switch 51 to control the first electronic switch 51 to be disconnected. At this time, the first resistor R47 and the second resistor R15 are connected in series and in series between the output end of the power amplifier U7 and one end of the load 12. The current monitoring chip U4 detects the voltage between the first end of the first resistor R47 and the second end of the second resistor R15, and then calculates the output current value of the power amplifier U7 according to Ohm's law; when the output current value of the power amplifier U7 detected by the current detection circuit 5 is greater than the aforementioned preset threshold value, the MCU control circuit 3 sends a control signal to the control end of the first electronic switch 51 to control the first electronic switch 51 to be closed. At this time, the first resistor R47 is short-circuited, and the current monitoring chip U4 detects the voltage between the second end of the second resistor R15. The voltage across the resistor R15 is then used to calculate the output current value of the power amplifier U7 using Ohm's law. This allows the output current of the power amplifier U7 to be detected by using a larger detection resistor (i.e., the first resistor R47 and the second resistor R15 are connected in series as a detection resistor) in combination with the current monitoring chip U4 when the output current value of the power amplifier U7 is small (e.g., the output current value is in the microampere level), thereby greatly improving the current detection accuracy. When the output current value of the power amplifier U7 is large (e.g., the output current is several amperes), a smaller detection resistor (i.e., only the second resistor R15 is used as the detection resistor) in combination with the current monitoring chip U4 is used to detect the output current of the power amplifier U7, thereby avoiding the voltage drop across the detection resistor exceeding the voltage range of the current monitoring chip U4, thereby improving the measurement accuracy, and thereby enabling the current detection circuit 5 to have a wider current detection range and a wider range of applications.

[0034] See also Figure 2As shown, in this embodiment, further, the current detection circuit 5 also includes a second electronic switch 52, the second electronic switch 52 is a single-pole double-throw electronic switch, the control end of the second electronic switch 52 is connected to the MCU control circuit 3, the output end of the power amplifier U7 is connected to the first input end of the second electronic switch 52, the first end of the second resistor R15 is connected to the second input end of the second electronic switch 52, and the output end of the second electronic switch 52 is connected to the first input end of the current monitoring chip U4, that is, the output end of the power amplifier U7 and the first end of the second resistor R15 are respectively connected to the first input end of the current monitoring chip U4 through the second electronic switch 52. In this embodiment, when the output current value of the power amplifier U7 detected by the current detection circuit 5 is less than or equal to the aforementioned preset threshold value, the MCU control circuit 3 sends a control signal to the control end of the first electronic switch 51 to control the first electronic switch 51 to be disconnected. At the same time, the MCU control circuit 3 also sends a control signal to the control end of the second electronic switch 52 to control the second electronic switch 52 to connect the output end of the power amplifier U7 with the first input end of the current monitoring chip U4, so that the current monitoring chip U4 can detect the voltage between the first end of the first resistor R47 and the second end of the second resistor R15; when the output current value of the power amplifier U7 detected by the current detection circuit 5 is greater than the aforementioned preset threshold value, the MCU control circuit 3 sends a control signal to the control end of the second electronic switch 52 to control the second electronic switch 52 to connect the output end of the power amplifier U7 with the first input end of the current monitoring chip U4, so that the current monitoring chip U4 can detect the voltage between the first end of the first resistor R47 and the second end of the second resistor R15. While the control circuit 3 sends a control signal to the control end of the first electronic switch 51 to control the first electronic switch 51 to close, the MCU control circuit 3 also sends a control signal to the control end of the second electronic switch 52 to control the second electronic switch 52 to connect the first end of the second resistor R15 with the first input end of the current monitoring chip U4. The first electronic switch 51 has a certain loss, and a certain voltage drop will be formed at its two ends. By connecting the first end of the second resistor R15 with the first input end of the current monitoring chip U4 through the second electronic switch 52, the current monitoring chip U4 can avoid taking the voltage drop across the first electronic switch 51 into account when detecting the voltage across the second resistor R15, thereby further improving the measurement accuracy.

[0035] In this embodiment, the resistance of the first resistor R47 is greater than the resistance of the second resistor R15, the power that the first resistor can withstand is greater than 4W, the power that the second resistor can withstand is greater than 1W, the resistance of the first resistor R47 is specifically 39.9Ω, the resistance of the second resistor R15 is specifically 0.1Ω, the first electronic switch 51 and the second electronic switch 52 are both relays; the MCU control circuit 3 is specifically through I 2C communication and current monitoring chip U4 perform signal transmission. The current monitoring chip U4 adopts a current / power monitoring chip that can simultaneously monitor the output current, output voltage and output power of the power amplifier U7 and feed back the monitoring results to the MCU control circuit 3. Specifically, a current / power monitoring chip of model INA219BIDCNR is adopted. Specifically, when it is necessary to monitor the output voltage of the power amplifier U7, the MCU control circuit 3 sends a control signal to the current / power monitoring chip to control it to detect the voltage between the second end of the second resistor R15 and the signal ground (that is, the output voltage of the power amplifier U7), and feeds back the detection result to the MCU control Circuit 3, MCU control circuit 3 sends a corresponding voltage control signal to power amplifier U7 to adjust the output voltage according to the detection result; when it is necessary to monitor the output current of power amplifier U7, MCU control circuit 3 sends a control signal to the current / power monitoring chip to control it to detect the voltage across the second resistor R15 or the voltage between the first end of the first resistor R47 and the second end of the second resistor R15, and then calculates the output current value of power amplifier U7 according to Ohm's law, and feeds back the detection result to MCU control circuit 3, MCU control circuit 3 sends a corresponding current control signal to power amplifier U7 to adjust the output current according to the detection result. Of course, in other embodiments, the current monitoring chip U4 can also use other types of chips, and the specific implementation method is not limited to this.

[0036] See also Figure 1 As shown, in this embodiment, a first impedance matching circuit 6 and a second impedance matching circuit 7 are further included, and the first output end of the digital-to-analog conversion unit 4 is connected to the voltage control end of the power amplifier U7 through the first impedance matching circuit 6, and the second output end of the digital-to-analog conversion unit 4 is connected to the current control end of the power amplifier U7 through the second impedance matching circuit 7. Specifically, in this embodiment, since the output impedance of the digital-to-analog conversion unit 4 is relatively large, and the input impedance of the power amplifier U7 is relatively small, impedance matching is performed by setting the first impedance matching circuit 6 and the second impedance matching circuit 7.

[0037] See also Figure 1 As shown, in this embodiment, an LCD display unit 10 and a USB module 11 are further included. The LCD display unit 10 and the USB module 11 are respectively connected to the MCU control circuit 3. The LCD display unit 10 is used to display the working status of the DC output power supply (such as output voltage, output current, output power, the state of the first electronic switch 51 and the state of the second electronic switch 52, etc.) and a human-computer interaction interface. The user can set the output voltage, output current, output power, etc. of the DC output power supply through the human-computer interaction interface. The host computer can be connected to the MCU control circuit 3 through the USB module 11 to control the DC output power supply, and the MCU control circuit 3 can also be upgraded through the USB module 11.

[0038] See also Figure 1 As shown, in this embodiment, a DC-DC switching power supply circuit 8 and an LDO buck circuit 9 are also included. The output end of the AC-DC switching power supply circuit 1 is connected to the input end of the DC-DC switching power supply circuit 8, and the output end of the DC-DC switching power supply circuit 8 is connected to the input end of the LDO buck circuit 9. The output end of the LDO buck circuit 9 is respectively connected to the MCU control circuit 3, the digital-to-analog conversion unit 4, the current detection circuit 5, the first impedance matching circuit 6, the second impedance matching circuit 7, the LCD display unit 10 and the USB module 11 to power each circuit or module, and the LDO buck circuit 9 can also perform linear voltage regulation. In this embodiment, the power required for the power supply of the MCU control circuit 3, the digital-to-analog conversion unit 4, the current detection circuit 5, the first impedance matching circuit 6, the second impedance matching circuit 7, the LCD display unit 10 and the USB module 11 is relatively small, so the volume and weight of the DC-DC switching power supply circuit 8 here are not too large.

[0039] In this embodiment, the input end of the AC-DC switching power supply circuit 1 is connected to the 220V AC mains, and the 220V AC power supply is stepped down to 15V by the AC-DC switching power supply circuit 1 as the input of the power amplifier U7. The power amplifier U7 adjusts the output voltage and output current according to the control signal sent by the MCU control circuit 3 to achieve the technical indicators of the output voltage range of 0 to 12V and the output current range of 0 to 2A; at the same time, the 15V DC power output by the AC-DC switching power supply circuit 1 is stepped down to 7V by the DC-DC switching power supply circuit 8, and then stepped down to 5V by the LDO step-down circuit 9. In this embodiment, the AC-DC switching power supply circuit 1 adopts a high-frequency switching power supply circuit, which helps to further reduce the volume and weight of the DC output power supply compared to the industrial frequency AC-DC switching power supply circuit 1. In this embodiment, the AC-DC switching power supply circuit 1 can be implemented by an existing rectifier circuit, which is not described in detail.

[0040] See also Figure 3 As shown, in this embodiment, the MCU control circuit 3 includes a main control chip U5, the model of the main control chip U5 is ATMEGA2560-16AU, and the main control chip U5 includes 100 pins. The corresponding English labels of the pins are as follows: Figure 3 shown.

[0041] See also Figure 4 As shown, in this embodiment, the digital-to-analog conversion unit 4 includes a digital-to-analog conversion chip U6, the model of the digital-to-analog conversion chip U6 is MCP47FVB22A0T-E / ST, combined with Figure 1 The connection relationship in Figure 4 Pins 7 and 8 of the digital-to-analog converter chip U6 are respectively connected to Figure 3Pins 43 and 44 of the central control chip U5 are connected.

[0042] See also Figure 5 As shown, in this embodiment, the first impedance matching circuit 6 includes a voltage follower U9A, which has the characteristics of high input impedance and low output impedance. Figure 1 The connection relationship in Figure 5 Pin 3 of the medium voltage follower U9A is connected to Figure 4 Pin 4 of the digital-to-analog converter chip U6 is connected; see Figure 6 As shown, in this embodiment, the second impedance matching circuit 7 includes a voltage follower U9B, combined with Figure 1 The connection relationship in Figure 6 Pin 5 of the medium voltage follower U9B is connected to Figure 4 The digital-to-analog converter chip U6 is connected to pin 3.

[0043] See also Figure 7 As shown, in this embodiment, the model of the power amplifier U7 is OPA548T, combined with Figure 1 The connection relationship in Figure 7 Pin 1 of the medium power amplifier U7 (i.e., the voltage control terminal of the power amplifier U7) is connected to Figure 5 Pin 1 of the medium voltage follower U9A is connected to Figure 7 Pin 3 of the medium power amplifier U7 (i.e., the current control terminal of the power amplifier U7) is connected to Figure 6 Pin 7 of the medium voltage follower U9B is connected; Figure 7 Pin 2 of the medium power amplifier U7 is connected to the signal ground through the fifth resistor R28. Figure 7 The pin 2 of the medium power amplifier U7 is also connected to the pin 6 of the power amplifier U7 (i.e., the output end of the power amplifier U7) through the sixth resistor R29. Figure 7 Pin 4 of the medium power amplifier U7 is grounded. Figure 7 Pin 5 of the medium power amplifier U7 (i.e., the power supply input terminal of the power amplifier U7) is connected to the output terminal of the AC-DC switching power supply circuit 1. Figure 7 Pin 7 of the medium power amplifier U7 is connected to Figure 3 Connect to pin 1 of the main control chip U5.

[0044] See also Figure 8 As shown, in this embodiment, the first electronic switch 51 and the second electronic switch 52 are implemented by the same relay K4, and the specific model of the relay K4 is HF115F012-2ZS4AF (310); Figure 1 The connection relationship in Figure 8 Pins 5 and 6 of the medium current monitoring chip U4 are respectively connected to Figure 3 Connect pins 43 and 44 of the main control chip U5; Figure 2 The connection relationship in Figure 8 In the embodiment, the pin 2 of the relay K4 is connected to the first end of the first resistor R47, the pin 3 of the relay K4 is connected to the second end of the first resistor R47, the pin 5 of the relay K4 is connected to the first end of the first resistor R47, the pin 6 of the relay K4 is connected to the pin 2 of the current monitoring chip U4, the pin 7 of the relay K4 is connected to the second end of the first resistor R47, and the pin 1 of the current monitoring chip U4 is connected to the second end of the second resistor R15. Of course, in other embodiments, the first electronic switch 2 and the second electronic switch 3 may also use two different relays, which can also achieve the purpose of the present invention.

[0045] See also Figure 8 As shown, in this embodiment, the current detection circuit 5 further includes a third resistor R48, a fourth resistor R49, a transistor Q1 and a diode D18, and the first end of the third resistor R48 is connected to Figure 3 The second end of the third resistor R48 is connected to the first end of the fourth resistor R49 and the base of the transistor Q1 respectively, the second end of the fourth resistor R49 and the emitter of the transistor Q1 are both connected to the signal ground, the collector of the transistor Q1 is connected to the input end of the diode D18 and the pin 8 of the relay K4 respectively, the output end of the diode D18 and the pin 1 of the relay K4 are both connected to the output end of the AC-DC switching power supply circuit 1. Figure 3 When pin 5 of the main control chip U5 outputs a high level, transistor Q1 is turned on, the coil of relay K4 is energized, pins 2 and 3 of relay K4 are disconnected (i.e., the first electronic switch 51 is disconnected), and pins 5 and 6 of relay K4 are connected (i.e., the second electronic switch 52 connects the first end of the first resistor R47 to the first input end of the current monitoring chip U4); when Figure 3 When pin 5 of the main control chip U5 outputs a low level, the transistor Q1 is turned off, the coil of the relay K4 is not energized, pins 2 and 3 of the relay K4 are connected (that is, the first electronic switch 51 is closed), and pins 6 and 7 of the relay K4 are connected (that is, the second electronic switch 52 connects the first end of the second resistor R15 to the first input end of the current monitoring chip U4).

[0046] See also Figures 9 and 10 As shown, Fig. 9 FIG. 8 shows a circuit schematic diagram of a DC-DC switching power supply circuit 8. Fig.10 . The circuit principle diagram of the LDO buck circuit 9 is shown in FIG.

[0047] See also Fig.11 As shown, in this embodiment, the USB module 11 includes a USB to serial port chip U10, the model of the USB to serial port chip U10 is CH340G, combined with Figure 1 The connection relationship in Fig.11 The pins 2 and 3 of the USB to serial port chip U10 are respectively connected to Figure 3 Pins 2 and 3 of the main control chip U5 are connected.

[0048] From the above description of the present invention, it can be seen that compared with the prior art, the circuit structure of the present invention is simple, and the output voltage and output current are adjusted by using a power amplifier circuit constructed by a power amplifier with a smaller volume and weight combined with an MCU control circuit, which can greatly reduce the volume and weight of the DC output power supply, so that the whole machine has the characteristics of small size, light weight and easy mobility.

[0049] The above embodiments are only used to further illustrate a DC output power supply of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the protection scope of the technical solution of the present invention.

Claims

1. A DC output power supply, characterized in that: It includes an AC-DC switching power supply circuit, a power amplifier circuit, an MCU control circuit and a digital-to-analog conversion unit, wherein the power amplifier circuit includes a power amplifier, the output end of the AC-DC switching power supply circuit is connected to the power supply input end of the power amplifier, the control signal output end of the MCU control circuit is connected to the input end of the digital-to-analog conversion unit, the first output end of the digital-to-analog conversion unit is connected to the voltage control end of the power amplifier, and the second output end of the digital-to-analog conversion unit is connected to the current control end of the power amplifier; It also includes a current detection circuit for detecting the output current value of the power amplifier, wherein the input end of the current detection circuit is connected to the output end of the power amplifier, and the current detection circuit is connected to the MCU control circuit; The current detection circuit includes a first resistor, a second resistor, a first electronic switch, a second electronic switch and a current monitoring chip; the output end of the power amplifier is respectively connected to the first end of the first resistor, the input end of the first electronic switch and the first input end of the second electronic switch, the first end of the second resistor is respectively connected to the second end of the first resistor, the output end of the first electronic switch and the second input end of the second electronic switch, the output end of the second electronic switch is connected to the first input end of the current monitoring chip, the second end of the second resistor is connected to the second input end of the current monitoring chip, the control end of the first electronic switch and the output end of the current monitoring chip are respectively connected to the MCU control circuit, and the control end of the second electronic switch is connected to the MCU control circuit; the second electronic switch is a single-pole double-throw electronic switch.

2. The DC output power supply according to claim 1, characterized in that: The resistance value of the first resistor is greater than the resistance value of the second resistor.

3. The DC output power supply according to claim 1, characterized in that: The model of the current monitoring chip is INA219BIDCNR.

4. The DC output power supply according to claim 1, characterized in that: It also includes a first impedance matching circuit and a second impedance matching circuit. The first output end of the digital-to-analog conversion unit is connected to the voltage control end of the power amplifier through the first impedance matching circuit, and the second output end of the digital-to-analog conversion unit is connected to the current control end of the power amplifier through the second impedance matching circuit.

5. The DC output power supply according to claim 1, characterized in that: It also includes a DC-DC switching power supply circuit and an LDO step-down circuit, wherein the output end of the AC-DC switching power supply circuit is connected to the input end of the DC-DC switching power supply circuit, the output end of the DC-DC switching power supply circuit is connected to the input end of the LDO step-down circuit, and the output end of the LDO step-down circuit is connected to the MCU control circuit.

6. The DC output power supply according to claim 1, characterized in that: It also includes an LCD display unit and a USB module, and the LCD display unit and the USB module are respectively connected to the MCU control circuit.

7. The DC output power supply according to claim 1, characterized in that: The model of the power amplifier is OPA548T.

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