current detection circuit
By designing a signal generation circuit and an analog-to-digital conversion circuit that includes a sampling resistor and a differential amplifier, the problems of narrow application range and easy damage of existing current detection circuits are solved, enabling wider application and improved circuit safety.
Patent Information
- Application Number
- CN202521846624.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-08-28
AI Technical Summary
Existing current detection circuits have a narrow application range and are easily damaged when the input signal is overvoltage, which endangers circuit safety.
A current detection circuit including a signal generation circuit and an analog-to-digital conversion circuit is designed. The signal generation circuit includes a sampling resistor and a differential amplifier. The differential amplifier is an operational amplifier with overvoltage protection function. The analog-to-digital conversion circuit is used to convert the sampled signal into a digital signal and transmit it to the current manager.
This expands the application range of current detection circuits and effectively protects the components in the circuit through overvoltage protection, thereby improving the safety of current detection circuits.
Smart Images
Figure CN224682318U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of current detection technology, and more specifically, to a current detection circuit. Background Technology
[0002] In electronic systems, current sensing is a fundamental and crucial function, widely used in power management, motor control, and battery protection. In practical applications, current sensing circuits are often used to directly acquire electrical signals from the circuit and transmit these signals to a specific current sensing device to achieve current detection. However, this method has a narrow application range, and when the circuit voltage experiences transient changes or when the circuit is connected, disconnected, or turned off, the current sensing circuit may encounter overvoltage conditions. Such overvoltage can easily damage components in the circuit, affecting circuit safety, and this situation must be avoided. Utility Model Content
[0003] This application provides a current detection circuit that can solve the problems of narrow application range and easy damage to the circuit when the input signal is overvoltage, which endangers circuit safety.
[0004] To achieve this objective, the embodiments of this application provide the following solutions.
[0005] According to one aspect of the embodiments of this application, a current detection circuit is provided, including a signal generation circuit and an analog-to-digital conversion circuit. The signal generation circuit includes a sampling resistor and a differential amplifier circuit with a differential amplifier. The sampling resistor is connected in series with the circuit to be detected. The input terminal of the differential amplifier is electrically connected to the sampling resistor, and the output terminal is connected to the analog-to-digital conversion circuit to output a sampling signal corresponding to the sampling resistor. The differential amplifier is an operational amplifier with overvoltage protection function. The analog-to-digital converter circuit is connected to the current manager and is used to convert the sampled signal into a digital signal and transmit the digital signal to the current manager.
[0006] In one possible implementation, the differential amplifier circuit includes a first resistor, a second resistor, a third resistor, and a fifth resistor. The first end of the first resistor is connected to the first end of the sampling resistor. The first end of the second resistor is connected to the second end of the sampling resistor. The second end of the first resistor is connected to the non-inverting input of the operational amplifier and the first end of the fifth resistor. The second end of the fifth resistor is connected to the input of the analog-to-digital converter circuit, the output of the operational amplifier, and the second end of the third resistor. The first end of the third resistor is connected to the second end of the second resistor and the inverting input of the operational amplifier.
[0007] In one possible implementation, the first resistor and the second resistor have the same resistance value, and the third resistor and the fifth resistor have the same resistance value.
[0008] In one possible implementation, the analog-to-digital conversion circuit includes an analog-to-digital converter, a first capacitor, and a sixth resistor. The first end of the sixth resistor is connected to the output of the differential amplifier circuit, and the second end of the sixth resistor is connected to the signal input of the analog-to-digital converter and the first end of the first capacitor. The second end of the first capacitor is grounded.
[0009] In one possible implementation, the current detection circuit further includes a power supply circuit, the positive power supply pin of the operational amplifier is connected to the output terminal of the power supply circuit, and the analog-to-digital converter circuit further includes a second capacitor and a third capacitor, the first terminal of the second capacitor and the first terminal of the third capacitor are grounded, and the second terminal of the second capacitor and the second terminal of the third capacitor are connected to the output terminal of the power supply circuit and the voltage input terminal of the analog-to-digital converter.
[0010] In one possible implementation, the power supply circuit includes a buck converter chip and a second inductor. The power output pin of the buck converter chip is connected to a first terminal of the second inductor, and the second terminal of the second inductor is connected to the analog-to-digital converter and the operational amplifier.
[0011] In one possible implementation, the power supply circuit includes a sixth capacitor and a seventh capacitor, the second terminals of the sixth capacitor and the seventh capacitor are grounded and connected to the ground pin of the buck chip, and the first terminals of the sixth capacitor and the seventh capacitor are connected to the voltage source and the voltage input terminal of the buck chip.
[0012] In one possible implementation, the power supply circuit further includes a seventh resistor and a light-emitting diode (LED). The first end of the seventh resistor is connected to the second end of the second inductor, the second end of the seventh resistor is connected to the anode of the LED, and the cathode of the LED is grounded.
[0013] In one possible implementation, the power supply circuit further includes an eighth resistor and a ninth resistor, with the second end of the eighth resistor grounded, the first end of the eighth resistor connected to the second end of the ninth resistor and the voltage feedback pin of the step-down chip, and the first end of the ninth resistor connected to the second end of the second inductor.
[0014] In one possible implementation, the power supply circuit includes a third diode, a ninth capacitor, and a tenth capacitor. The anode of the third diode is grounded and connected to the second terminal of the ninth capacitor and the second terminal of the tenth capacitor. The cathode of the third diode is connected to the first terminal of the second inductor. The first terminals of the ninth capacitor and the tenth capacitor are connected to the second terminal of the second inductor.
[0015] The beneficial effects of the technical solutions provided in this application are: The current detection circuit provided in this application includes a signal generation circuit and an analog-to-digital conversion circuit. The signal generation circuit includes a sampling resistor and a differential amplifier circuit with a differential amplifier. The sampling resistor is connected in series with the circuit under test. The input terminal of the differential amplifier is electrically connected to the sampling resistor, and the output terminal is connected to the analog-to-digital conversion circuit to output the sampling signal corresponding to the sampling resistor. The differential amplifier is an operational amplifier with overvoltage protection. The analog-to-digital conversion circuit is connected to a current manager and is used to convert the sampling signal into a digital signal and transmit the digital signal to the current manager. In this embodiment, the sampling signal is transmitted to the analog-to-digital conversion circuit through the signal generation circuit to obtain a digital signal characterizing the current detection result, effectively expanding the application range of current detection. Furthermore, the operational amplifier in the signal generation circuit provides overvoltage protection, thereby effectively protecting the components in the current detection circuit and improving the safety of the current detection circuit. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below.
[0017] Figure 1 The circuit diagram of the signal generation circuit and analog-to-digital conversion circuit in the current detection circuit provided in the embodiments of this application; Figure 2 A circuit diagram of the power supply circuit provided in the embodiments of this application; Figure 3 This is a flowchart illustrating the operation of the current detection circuit provided in an embodiment of this application.
[0018] Label Explanation: R4, sampling resistor; U1, operational amplifier; R1, first resistor; R2, second resistor; R3, third resistor; R5, fifth resistor; U2, analog-to-digital converter; C1, first capacitor; R6, sixth resistor; C2, second capacitor; C3, third capacitor; U3, step-down chip; L2, second inductor; R7, seventh resistor; D4, light-emitting diode; R8, eighth resistor; R9, ninth resistor; D3, third diode; C9, ninth capacitor; C10, tenth capacitor. Detailed Implementation
[0019] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.
[0020] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the terms “comprising” and “including” as used in embodiments of this application mean that the corresponding feature can be implemented as the presented feature, information, data, step, operation, element, and / or component, but do not exclude implementation as other features, information, data, step, operation, element, component, and / or combinations thereof supported by the art. It should be understood that when we say that an element is “connected” or “coupled” to another element, the one element can be directly connected or coupled to the other element, or it can mean that the one element and the other element establish a connection relationship through an intermediate element. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein indicates at least one of the items defined by the term; for example, “A and / or B” indicates implementation as “A,” or implementation as “A,” or implementation as “A and B.”
[0021] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.
[0022] The technical solutions of this utility model and their effects are described below through several exemplary embodiments. It should be noted that the following embodiments can be referenced, borrowed from, or combined with each other. Identical terms, similar features, and similar implementation steps in different embodiments will not be repeated.
[0023] The current detection circuit provided in this application is intended to solve at least one technical problem existing in the prior art.
[0024] This application provides a current detection circuit, such as... Figures 1-3As shown, the current detection circuit includes a signal generation circuit and an analog-to-digital conversion circuit. The signal generation circuit includes a sampling resistor R4 and a differential amplifier circuit with a differential amplifier. The sampling resistor R4 is connected in series with the circuit under test. The input terminal of the differential amplifier is electrically connected to the sampling resistor R4, and the output terminal is connected to the analog-to-digital conversion circuit to output the sampling signal corresponding to the sampling resistor R4. The differential amplifier is an operational amplifier U1 with overvoltage protection. The analog-to-digital conversion circuit is connected to the current manager and is used to convert the sampling signal into a digital signal and transmit the digital signal to the current manager. By converting the sampling signal into a digital signal, the types of current managers that the current detection circuit can be connected to are effectively increased, expanding its application range.
[0025] Optionally, the current manager can be a microcontroller, DSP, CPU, or other device that needs to acquire current detection results.
[0026] In one embodiment, the current manager can be a microcontroller, and the analog-to-digital conversion circuit includes an analog-to-digital converter U2. The conversion process and data acquisition process of the microcontroller are implemented through the CS pin and the serial clock SCLK pin of the analog-to-digital converter U2. The current manager can be electrically connected to the circuit under test and control the circuit under test according to the digital signal output by the analog-to-digital converter circuit. It can also output a corresponding response signal based on the digital signal and transmit the response signal to other devices, or transmit the received digital signal to other devices.
[0027] Optionally, operational amplifier U1 can be an ADA4096, which features input overvoltage protection. It prevents phase reversal or latch-up for input voltages within a 32V range above or below the power supply rail, thus providing effective protection. Alternatively, operational amplifier U1 can be a MAX44205, AD629, ADA4091-2, or other operational amplifiers with overvoltage protection.
[0028] Optionally, the differential amplifier circuit includes a first resistor R1, a second resistor R2, a third resistor R3, and a fifth resistor R5. The first terminal of the first resistor R1 is connected to the first terminal of the sampling resistor R4. The first terminal of the second resistor R2 is connected to the second terminal of the sampling resistor R4. The second terminal of the first resistor R1 is connected to the non-inverting input terminal of operational amplifier U1 and the first terminal of the fifth resistor R5. The second terminal of the fifth resistor R5 is connected to the input terminal of the analog-to-digital converter circuit, the output terminal of operational amplifier U1, and the second terminal of the third resistor R3. The first terminal of the third resistor R3 is connected to the second terminal of the second resistor R2 and the inverting input terminal of operational amplifier U1. Ratio matching is achieved through the first resistor R1, second resistor R2, third resistor R3, and fifth resistor R5. The gain of operational amplifier U1 is related to the resistance values of the first resistor R1, second resistor R2, third resistor R3, and fifth resistor R5. Furthermore, operational amplifier U1 detects the voltage across the sampling resistor R4 and suppresses common-mode voltage.
[0029] Optionally, the two ends of the sampling resistor R4 can be connected to the circuit under test via a connector, wherein the connector model can be HDR-F-2.54_1x2.
[0030] Optionally, the first resistor R1 and the second resistor R2 have the same resistance value, and the third resistor R3 and the fifth resistor R5 have the same resistance value. The gain (amplification factor) of the operational amplifier U1 is the ratio of the resistance value of the third resistor R3 to the resistance value of the first resistor R1, or the ratio of the resistance value of the fifth resistor R5 to the resistance value of the second resistor R2.
[0031] In one embodiment, the resistance of the first resistor R1 and the second resistor R2 is 1KΩ, and the resistance of the third resistor R3 and the fifth resistor R5 is 20KΩ. The voltage to ground at the first terminal of the sampling resistor R4 can be va, and the voltage at the second terminal can be vb. The output voltage of the operational amplifier U1 is vout = (va - vb) 20KΩ / 1KΩ.
[0032] Optionally, the analog-to-digital conversion circuit includes an analog-to-digital converter U2, a first capacitor C1, and a sixth resistor R6. The first end of the sixth resistor R6 is connected to the output end of the differential amplifier circuit, the second end of the sixth resistor R6 is connected to the signal input end of the analog-to-digital converter U2 and the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded.
[0033] Optionally, the resistance of the sixth resistor R6 can be 0Ω, and the first capacitor C1 can be a debugging capacitor, which can be left unconnected to the circuit or connected to the circuit according to the test results after the current detection circuit has been tested.
[0034] In one embodiment, the analog-to-digital converter U2 can be an XC7886, a 12-bit ADC chip with high resolution, high speed, low power consumption, small size, and unipolarity. The XC7886 chip operates from a single 4V-5.25V power supply and has a maximum sampling rate of 800KSPS. The conversion and data acquisition processes are controlled via the CS pin and the serial clock SCLK pin, thus enabling its connection to MCUs, DSPs, and other microprocessors. The model of the analog-to-digital converter U2 can be CM4221, AD9226ARSZ, or other models, and is not limited thereto.
[0035] Optionally, the current detection circuit also includes a power supply circuit, the positive power supply pin of the operational amplifier U1 is connected to the output terminal of the power supply circuit, and the analog-to-digital converter circuit also includes a second capacitor C2 and a third capacitor C3. The first terminal of the second capacitor C2 and the first terminal of the third capacitor C3 are grounded, and the second terminal of the second capacitor C2 and the second terminal of the third capacitor C3 are connected to the output terminal of the power supply circuit and the voltage input terminal of the analog-to-digital converter U2.
[0036] In one embodiment, the power supply circuit can output 5V DC, and the operational amplifier U1 and analog-to-digital converter U2 operate at 5V. Alternatively, when the operational amplifier U1 and analog-to-digital converter U2 operate at 3.3V, the power supply circuit can also output 3.3V DC.
[0037] Optionally, the power supply circuit includes a step-down chip U3 and a second inductor L2. The power output pin of the step-down chip U3 is connected to the first end of the second inductor L2, and the second end of the second inductor L2 is connected to the analog-to-digital converter U2 and the operational amplifier U1.
[0038] Optionally, the buck converter U3 can be the TPS5430DDAR, a high-output-current PWM converter integrating a low-resistance, high-side N-channel MOSFET. This buck converter U3 provides tight voltage regulation accuracy under transient conditions. It features an internal undervoltage lockout circuit to prevent startup before the input voltage reaches 5.5V; an internal slow-start circuit to limit inrush current; and a voltage feedforward circuit to improve transient response. The buck converter U3 also includes high active enable, overcurrent limiting, overvoltage protection, and thermal shutdown functions. The buck converter U3 can also be the LTC3703, SL3063, PW2205, or other types.
[0039] Optionally, the input voltage of the buck converter U3 can be 5.5V-36V. The buck converter U3 converts the electrical signal transmitted at the input terminal into 5V DC.
[0040] Optionally, the power supply circuit also includes a seventh resistor R7 and a light-emitting diode D4. The first end of the seventh resistor R7 is connected to the second end of the second inductor L2, and the second end of the seventh resistor R7 is connected to the anode of the light-emitting diode D4. The cathode of the light-emitting diode D4 is grounded. The light-emitting diode D4 indicates the operating status of the power supply circuit.
[0041] In one embodiment, the light-emitting diode D4 can emit red light when the power supply circuit is working normally, thereby indicating that the power supply circuit is currently working normally.
[0042] Optionally, the power supply circuit also includes an eighth resistor R8 and a ninth resistor R9. The second terminal of the eighth resistor R8 is grounded, and the first terminal of the eighth resistor R8 is connected to the second terminal of the ninth resistor R9 and the voltage feedback pin of the step-down chip U3. The first terminal of the ninth resistor R9 is connected to the second terminal of the second inductor L2. A voltage divider circuit is formed by the eighth resistor R8 and the ninth resistor R9. The step-down chip U3 detects whether the power supply circuit is working normally based on the potential value of the first terminal of the eighth resistor R8.
[0043] Optionally, the power supply circuit includes a third diode D3, a ninth capacitor C9, and a tenth capacitor C10. The anode of the third diode D3 is grounded and connected to the second terminal of the ninth capacitor C9 and the second terminal of the tenth capacitor C10. The cathode of the third diode D3 is connected to the first terminal of the second inductor L2. The first terminals of the ninth capacitor C9 and the tenth capacitor C10 are connected to the second terminal of the second inductor L2.
[0044] The current detection circuit of this application will be further explained below through its working process.
[0045] In one embodiment, such as Figure 3 As shown, after the power supply circuit starts, it supplies power to the signal generation circuit and the analog-to-digital conversion circuit, and the current detection circuit begins to work. The differential amplifier in the signal generation circuit detects the voltage of the sampling resistor R4 and outputs a sampling signal. The analog-to-digital converter U2 in the analog-to-digital conversion circuit receives the sampling signal and outputs a digital signal. The MCU processes the data corresponding to the digital signal output by the analog-to-digital converter U2 and generates a feedback signal, thereby completing the current detection.
[0046] The current detection circuit provided in this application includes a signal generation circuit and an analog-to-digital conversion circuit. The signal generation circuit includes a sampling resistor and a differential amplifier circuit with a differential amplifier. The sampling resistor is connected in series with the circuit under test. The input terminal of the differential amplifier is electrically connected to the sampling resistor, and the output terminal is connected to the analog-to-digital converter to output the sampling signal corresponding to the sampling resistor. The differential amplifier is an operational amplifier with overvoltage protection. The analog-to-digital conversion circuit is connected to a current manager and is used to convert the sampling signal into a digital signal and transmit the digital signal to the current manager. In this embodiment, the sampling signal is transmitted to the analog-to-digital conversion circuit through the signal generation circuit to obtain a digital signal characterizing the current detection result, effectively expanding the application range of current detection. Furthermore, the overvoltage protection is achieved through the operational amplifier in the signal generation circuit, thereby effectively protecting the components in the current detection circuit and improving the safety of the current detection circuit.
[0047] The terms "first," "second," "third," "fourth," "1," "2," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than that shown in the illustrations or text descriptions.
[0048] It should be understood that although arrows indicate various operation steps in the flowcharts of this application's embodiments, the order in which these steps are implemented is not limited to the order indicated by the arrows. Unless explicitly stated herein, in some implementation scenarios of this application's embodiments, the implementation steps in each flowchart can be executed in other orders as required. Furthermore, some or all steps in each flowchart, based on the actual implementation scenario, may include multiple sub-steps or multiple stages. Some or all of these sub-steps or stages can be executed at the same time, and each sub-step or stage can also be executed at different times. In scenarios where execution times differ, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and this application's embodiments do not limit this.
[0049] The above description is only an optional implementation method for some implementation scenarios of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application without departing from the technical concept of this application also fall within the protection scope of the embodiments of this application.
Claims
1. A current detection circuit, characterized in that, It includes a signal generation circuit and an analog-to-digital conversion circuit. The signal generation circuit includes a sampling resistor and a differential amplifier circuit with a differential amplifier. The sampling resistor is connected in series with the circuit to be tested. The input terminal of the differential amplifier is electrically connected to the sampling resistor, and the output terminal is connected to the analog-to-digital conversion circuit to output the sampling signal corresponding to the sampling resistor. The differential amplifier is an operational amplifier with overvoltage protection function. The analog-to-digital converter circuit is connected to the current manager and is used to convert the sampled signal into a digital signal and transmit the digital signal to the current manager.
2. The current detection circuit according to claim 1, characterized in that, The differential amplifier circuit includes a first resistor, a second resistor, a third resistor, and a fifth resistor. The first end of the first resistor is connected to the first end of the sampling resistor. The first end of the second resistor is connected to the second end of the sampling resistor. The second end of the first resistor is connected to the non-inverting input terminal of the operational amplifier and the first end of the fifth resistor. The second end of the fifth resistor is connected to the input terminal of the analog-to-digital converter circuit, the output terminal of the operational amplifier, and the second end of the third resistor. The first end of the third resistor is connected to the second end of the second resistor and the inverting input terminal of the operational amplifier.
3. The current detection circuit according to claim 2, characterized in that, The first resistor and the second resistor have the same resistance value, and the third resistor and the fifth resistor have the same resistance value.
4. The current detection circuit according to claim 1, characterized in that, The analog-to-digital conversion circuit includes an analog-to-digital converter, a first capacitor, and a sixth resistor. The first end of the sixth resistor is connected to the output end of the differential amplifier circuit, and the second end of the sixth resistor is connected to the signal input end of the analog-to-digital converter and the first end of the first capacitor. The second end of the first capacitor is grounded.
5. The current detection circuit according to claim 4, characterized in that, The current detection circuit also includes a power supply circuit. The positive power supply pin of the operational amplifier is connected to the output terminal of the power supply circuit. The analog-to-digital conversion circuit also includes a second capacitor and a third capacitor. The first terminal of the second capacitor and the first terminal of the third capacitor are grounded. The second terminal of the second capacitor and the second terminal of the third capacitor are connected to the output terminal of the power supply circuit and the voltage input terminal of the analog-to-digital converter.
6. The current detection circuit according to claim 5, characterized in that, The power supply circuit includes a step-down chip and a second inductor. The power output pin of the step-down chip is connected to the first end of the second inductor, and the second end of the second inductor is connected to the analog-to-digital converter and the operational amplifier.
7. The current detection circuit according to claim 6, characterized in that, The power supply circuit includes a sixth capacitor and a seventh capacitor. The second terminals of the sixth capacitor and the seventh capacitor are grounded and connected to the ground pin of the step-down chip. The first terminals of the sixth capacitor and the seventh capacitor are connected to the voltage source and the voltage input terminal of the step-down chip.
8. The current detection circuit according to claim 6, characterized in that, The power supply circuit also includes a seventh resistor and a light-emitting diode. The first end of the seventh resistor is connected to the second end of the second inductor, the second end of the seventh resistor is connected to the anode of the light-emitting diode, and the cathode of the light-emitting diode is grounded.
9. The current detection circuit according to claim 6, characterized in that, The power supply circuit also includes an eighth resistor and a ninth resistor. The second end of the eighth resistor is grounded, the first end of the eighth resistor is connected to the second end of the ninth resistor and the voltage feedback pin of the step-down chip, and the first end of the ninth resistor is connected to the second end of the second inductor.
10. The current detection circuit according to claim 6, characterized in that, The power supply circuit includes a third diode, a ninth capacitor, and a tenth capacitor. The anode of the third diode is grounded and connected to the second terminal of the ninth capacitor and the second terminal of the tenth capacitor. The cathode of the third diode is connected to the first terminal of the second inductor. The first terminals of the ninth capacitor and the tenth capacitor are connected to the second terminal of the second inductor.