Low leakage current protection circuit
Through a low leakage current protection circuit composed of rectifier bridge, operational amplifier and transistor, the sampling resistance leakage current problem in current detection is solved, and high-precision wide range current detection is achieved.
Patent Information
- Application Number
- CN202411972703.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-05-16
AI Technical Summary
During the current detection process, it is difficult for the prior art to effectively reduce the leakage current of the sampling resistance, resulting in low measurement accuracy.
A low leakage current protection circuit consisting of a rectifier bridge, an operational amplifier and transistor is used to limit the voltage of the sampling resistor through the rectifier bridge. The operational amplifier is in a deep negative feedback state. The transistor is turned on for shunt protection when the current is too high.
Low leakage current protection is achieved, the accuracy and range of current detection is improved, and the risk of sampling resistance burning due to excessive current is avoided.
Smart Images
Figure CN120016399A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electronic information circuits, and in particular relates to a low leakage current protection circuit. Background Art
[0002] When using a power supply, users usually need to know the power consumption of the load so that they can design and evaluate the working condition of the load. When the user's load equipment is in different working states, such as sleep period, initial power-on, and normal operation, there may be large current changes. In the case of a large current change range, the safety of the sampling resistor needs to be ensured when detecting the current, and the protection circuit also needs to have a low leakage current to ensure measurement accuracy. Summary of the invention
[0003] In view of this, the present invention provides a low leakage current protection circuit, which can achieve low leakage current protection.
[0004] The technical solution for implementing the present invention is as follows:
[0005] A low leakage current protection circuit includes a large current sampling resistor R, a shunt protection module M1~M n , rectifier bridge U1, operational amplifier U2;
[0006] U1 includes 4 diodes d1, d2, d3, and d4;
[0007] R, M1, ..., M n Connected in series in sequence; the output end of R is connected to the positive input end of U1, the positive pole of the internal diode d1 of U1 is connected to the positive input end of U1, the negative pole of d1 is connected to the negative input end of U1, the positive pole of d4 is connected to the negative input end of U1, the negative pole of d4 is connected to the positive input end of U1, the negative pole of d2 and the positive pole of d3 are connected to the negative input end of U1, the positive pole of d2 and the negative pole of d3 are connected to the current output side, the negative input end of U1 is connected to the negative input end of U2, the negative input end of U2 is connected to the output end of U2, and the positive input end of U2 is connected to the middle of R and M1.
[0008] Furthermore, each shunt protection module includes a small current sampling resistor and a transistor; the transistor is connected in parallel at both ends of the small current sampling resistor.
[0009] Furthermore, when collecting a smaller current, it is generally sampled through a larger resistance sampling resistor; however, when the input current exceeds the sampling resistor R1-R n When the maximum allowed current exceeds a certain time, the sampling resistor will be burned out, and the rectifier bridge will limit the voltage of the sampling resistor. When the current is too large, the excess current will be shunted by the rectifier bridge to achieve a protective effect.
[0010] Furthermore, during normal operation, the amplifier circuit composed of the operational amplifier U2 is in a deep negative feedback state, the voltages at the positive and negative input terminals are approximately equal, and the voltage across the diode of the rectifier bridge is approximately 0. At this time, the leakage current of the diode is extremely small.
[0011] Furthermore, the circuit further comprises a switch control module, which is used to control transistors Q1 to Q n Each shunt protection module can set its own protection threshold and time for different sampling resistors; when R1~R n The current measured by each exceeds the preset threshold value I1~I n and time T1~T n When the switch control module controls transistors Q1~Q n Conductivity.
[0012] Beneficial effects:
[0013] 1. The present invention adopts a rectifier bridge, an operational amplifier and a transistor to form a low leakage protection circuit, realizes low leakage current protection for the current sampling resistor, and can achieve high-precision wide-range current detection of the power supply.
[0014] 2. The present invention generally uses a sampling resistor with a larger resistance value when detecting a smaller current, thereby improving the current detection accuracy.
[0015] 3. The present invention implements low leakage current protection for current sampling resistors, and multiple levels of current sampling resistors can be replaced based on actual current sampling values, thereby improving current detection accuracy and detection range. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a principle block diagram of the circuit of the present invention.
[0017] Figure 2 It is a principle block diagram of an embodiment of the present invention. DETAILED DESCRIPTION
[0018] The present invention is described in detail below with reference to the accompanying drawings and embodiments.
[0019] like Figure 1 As shown, the present invention provides a low leakage current protection circuit, including: a large current sampling resistor R, a shunt protection module M1~M n , rectifier bridge U1, operational amplifier U2; each shunt protection module includes a small current sampling resistor and a transistor; the transistor is connected in parallel at both ends of the small current sampling resistor. n is a sampling resistor for a smaller current, Q1-Q n For transistors.
[0020] I is the current to be measured. The rectifier bridge U1 is mainly used to protect the sampling resistor of smaller current. U1 includes four diodes d1, d2, d3, and d4.
[0021] R, M1, ..., M n Connected in series in sequence; the output end of R is connected to the positive input end of U1, the positive pole of the internal diode d1 of U1 is connected to the positive input end of U1, the negative pole of d1 is connected to the negative input end of U1, the positive pole of d4 is connected to the negative input end of U1, the negative pole of d4 is connected to the positive input end of U1, the negative pole of d2 and the positive pole of d3 are connected to the negative input end of U1, the positive pole of d2 and the negative pole of d3 are connected to the current output side, the negative input end of U1 is connected to the negative input end of U2, the negative input end of U2 is connected to the output end of U2, and the positive input end of U2 is connected to the middle of R and M1.
[0022] When collecting a small current, it is usually sampled through a larger resistance resistor. However, when the input current exceeds the sampling resistor R1-R n When the maximum current allowed exceeds a certain time, the sampling resistor will be burned out. At this time, the rectifier bridge limits the voltage of the sampling resistor. When the current is too large, the excess current is shunted by the rectifier bridge to achieve a protective effect.
[0023] During normal operation, the amplifier circuit composed of the operational amplifier U2 is in a deep negative feedback state, the voltages at the positive and negative input terminals are approximately equal, and the voltage across the diode of the rectifier bridge is approximately 0. At this time, the leakage current of the diode is extremely small.
[0024] like Figure 2 As shown, the circuit may further include a switch control module, the switch control module is used to control transistors Q1 to Q n Conducted separately, M1-M n The shunt protection module is the corresponding sampling resistor. Each shunt protection module can set its own protection threshold and time for different sampling resistors. n The current measured by each exceeds the preset threshold value I1~I n and time T1~T n When the switch control module controls transistors Q1~Q n Conductivity.
[0025] When using the sampling resistor R1-R n When sampling a small current, transistor Q1-Q n It is not conducting, and the PN junction of the body diode inside the transistor is in the reverse cut-off state with the direction of current from N to P. At this time, the leakage current is extremely small.
[0026] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A low leakage current protection circuit, characterized in that: Including large current sampling resistor R, shunt protection module M1~M n , rectifier bridge U1, operational amplifier U2; U1 includes 4 diodes d1, d2, d3, and d4; R, M1, ..., M n Connected in series in sequence; the output end of R is connected to the positive input end of U1, the positive pole of the internal diode d1 of U1 is connected to the positive input end of U1, the negative pole of d1 is connected to the negative input end of U1, the positive pole of d4 is connected to the negative input end of U1, the negative pole of d4 is connected to the positive input end of U1, the negative pole of d2 and the positive pole of d3 are connected to the negative input end of U1, the positive pole of d2 and the negative pole of d3 are connected to the current output side, the negative input end of U1 is connected to the negative input end of U2, the negative input end of U2 is connected to the output end of U2, and the positive input end of U2 is connected to the middle of R and M1.
2. The low leakage current protection circuit according to claim 1, characterized in that: Each shunt protection module includes a small current sampling resistor and a transistor; the transistor is connected in parallel at both ends of the small current sampling resistor.
3. The low leakage current protection circuit according to claim 2, characterized in that: When collecting a small current, it is usually sampled through a larger resistance resistor; however, when the input current exceeds the sampling resistor R1-R n When the maximum allowed current exceeds a certain time, the sampling resistor will be burned out, and the rectifier bridge will limit the voltage of the sampling resistor. When the current is too large, the excess current will be shunted by the rectifier bridge to achieve a protective effect.
4. The low leakage current protection circuit according to claim 2 or 3, characterized in that: During normal operation, the amplifier circuit composed of the operational amplifier U2 is in a deep negative feedback state, the voltages at the positive and negative input terminals are approximately equal, and the voltage across the diode of the rectifier bridge is approximately 0. At this time, the leakage current of the diode is extremely small.
5. The low leakage current protection circuit according to claim 2, characterized in that: The circuit also includes a switch control module, which is used to control transistors Q1 to Q n Each shunt protection module can set its own protection threshold and time for different sampling resistors; when R1~R n The current measured by each exceeds the preset threshold value I1~I n and time T1~T n When the switch control module controls transistors Q1~Q n Conductivity.