Current-limiting protection circuit based on current-limiting chip
By designing a current limit protection circuit based on a current limiting chip in the field of smart meter, the problem that traditional current limiting protection circuits are difficult to meet multiple outputs and high-precision current limiting protection is solved, and efficient and safe current limiting and stability improvement are achieved.
Patent Information
- Application Number
- CN202421787470.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-26
- Publication Date
- 2025-05-16
- Estimated Expiration
- 2034-07-26
AI Technical Summary
Traditional current limit protection circuits are difficult to meet the needs of multiple outputs and high-precision current limit protection in the field of smart meter, resulting in wasted CPU resources.
A current limit protection circuit based on a current limiting chip is designed, and the output voltage adjustment of the two outputs and linear regulators is achieved by introducing resistor R2, resistor R64 and current limiting chip U4.
It realizes current limit protection that responds quickly when a fault occurs, improves the safety and stability of the equipment, reduces power consumption, and has high accuracy and sensitivity.
Smart Images
Figure CN222884344U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of current limiting power supply circuits of electric meters, in particular to a current limiting protection circuit based on a current limiting chip. Background Art
[0002] Current limiting protection chips have many application scenarios. In electronic devices, it can be used for overcurrent protection of power lines, charging circuits, motor drives, etc. In the field of smart meters, it can provide overcurrent protection for switching power supplies, load circuits, etc. In addition, it can also be used in electric vehicles, solar cell groups, charging piles and other fields to improve the stability and safety of the equipment. Current limiting chips have broad development prospects. As society's demand for electronic equipment continues to increase, the market demand for overcurrent protection chips is also growing. At the same time, with the development of technology and the reduction of costs, overcurrent protection chips will be more suitable for various industries.
[0003] With the rapid development of the smart meter industry, the application market of smart meter products has become more and more extensive, and the requirements for the safety and stability of electrical equipment have become higher and higher. In the design and testing phase of smart meters, there are widespread current overloads and abnormal load short circuits. Once an overload such as a short circuit occurs, the load current will increase instantly, which will easily cause the line, devices, etc. to burn out. In severe cases, safety accidents such as fire may occur. In order to ensure the safe operation of related equipment and smart meters, current limiting chips are usually used to limit the load current. The current limiting protection chip is an important component for realizing overcurrent protection of electrical equipment. It is based on technology that adapts to different voltage and current requirements, and can effectively monitor and protect equipment from overcurrent damage.
[0004] In traditional current limiting protection circuits, a resistor is usually connected in series between the source and ground of the output tube. The current limiting current is calculated using the formula given in the specification, and the current limiting current can be adjusted according to the series resistor. However, in general, the current limiting chip has only one output voltage, and generally occupies a pin of the CPU system to detect the current limiting chip. This type of current limiting chip is difficult to meet the requirements of two output voltages. In the field of smart meters, if the meter has more functional requirements, the CPU IO ports may be insufficient, and the use of this current limiting chip will result in a waste of CPU resources. Utility Model Content
[0005] The utility model aims to solve the above problems and provides a current limiting protection circuit based on a current limiting chip to solve the above problems.
[0006] A current limiting protection circuit based on a current limiting chip comprises: a resistor R2, a resistor R64 and a current limiting chip U4, wherein the current limiting chip U4 comprises an input pin VIN, a feedback pin FB, an output pin OUT and an output pin LDOOUT, one end of the resistor R2 is connected to a ground terminal MKGND, and the other end is connected to a feedback pin FB of the current limiting chip U4; one end of the resistor R64 is connected to the feedback pin FB of the current limiting chip U4 and the resistor R2, and the other end is connected to the output pin LDOOUT of the current limiting chip U4; the resistor R2 is connected to the ground terminal MKGND.
[0007] Preferably, a capacitor C43 is further included, and the capacitor C43 is connected in series between the input pin VIN of the current limiting chip U4 and the ground terminal MKGND.
[0008] Preferably, a resistor R3 is further included, and the current limiting chip U4 further includes a setting pin ISET. The resistor R3 is connected in series between the setting pin ISET of the current limiting chip U4 and the ground terminal MKGND, and the setting pin ISET is used to limit current.
[0009] Preferably, an aluminum electrolytic capacitor CP36 is further included, wherein the positive electrode of the aluminum electrolytic capacitor CP36 is connected to the output pin LDOOUT of the current limiting chip U4, and the negative electrode of the aluminum electrolytic capacitor CP36 is connected to the ground terminal MKGND.
[0010] Preferably, a capacitor C64 is further included, and the capacitor C64 is connected in parallel to both ends of the aluminum electrolytic capacitor CP36.
[0011] Preferably, the current limiting chip U4 further includes a ground pin GND, and the ground pin GND is connected to the ground terminal MKGND.
[0012] Preferably, the resistor R2, the resistor R3 and the resistor R64 are chip resistors.
[0013] Preferably, the current limiting chip U4 is a DM7803 current limiting chip.
[0014] The utility model has the following advantages:
[0015] 1. The current limiting circuit can respond quickly when a fault occurs, limit the short-circuit current, and protect the safety of effective circuits and equipment;
[0016] 2. The output voltage of the two-way output linear regulator can be adjusted according to the matching resistor;
[0017] 3. With high accuracy and sensitivity, it can detect and respond to overcurrent conditions in a timely manner and effectively protect circuits and equipment;
[0018] 4. It has low power consumption and long life, and can maintain reliability during long-term operation;
[0019] 5. It has certain intelligent functions and can adjust parameters and perform adaptive control according to actual needs;
[0020] 6. Relatively low cost, easy to mass produce and promote application;
[0021] 7. The circuit is simple, low cost, high sensitivity, and has strong adaptability and practicality. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only one embodiment of the utility model. For ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.
[0023] Figure 1 : Schematic diagram of the circuit structure of the utility model;
[0024] Figure 2 : Schematic diagram of the circuit structure of the current limiting chip. DETAILED DESCRIPTION
[0025] The utility model is further described below with reference to the accompanying drawings and examples:
[0026] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.
[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0028] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0029] like Figure 1 and Figure 2 As shown, a current limiting protection circuit based on a current limiting chip includes: a resistor R2, a resistor R64 and a current limiting chip U4, wherein the current limiting chip U4 includes an input pin VIN, a feedback pin FB, an output pin OUT and an output pin LDOOUT, one end of the resistor R2 is connected to the ground terminal MKGND, and the other end is connected to the feedback pin FB of the current limiting chip U4; one end of the resistor R64 is connected to the feedback pin FB of the current limiting chip U4 and the resistor R2, and the other end is connected to the output pin LDOOUT of the current limiting chip U4; the resistor R2 is connected to the ground terminal MKGND. The resistor R2 and the resistor R64 are matching resistors for the output voltage of the output pin LDOOUT.
[0030] Preferably, a capacitor C43 is further included, and the capacitor C43 is connected in series between the input pin VIN of the current limiting chip U4 and the ground terminal MKGND.
[0031] Preferably, a resistor R3 is further included, and the current limiting chip U4 further includes a setting pin ISET. The resistor R3 is connected in series between the setting pin ISET of the current limiting chip U4 and the ground terminal MKGND, and the setting pin ISET is used to limit current.
[0032] Preferably, it also includes an aluminum electrolytic capacitor CP36, the positive electrode of the aluminum electrolytic capacitor CP36 is connected to the output pin LDOOUT of the current limiting chip U4, the negative electrode of the aluminum electrolytic capacitor CP36 is connected to the ground terminal MKGND, and the aluminum electrolytic capacitor CP36CP36 is used for filtering and energy storage.
[0033] Preferably, a capacitor C64 is further included, and the capacitor C64 is connected in parallel to both ends of the aluminum electrolytic capacitor CP36.
[0034] Preferably, capacitor C43 and capacitor C64 are chip ceramic capacitors for filtering out power supply interference.
[0035] Preferably, the current limiting chip U4 further includes a ground pin GND, and the ground pin GND is connected to the ground terminal MKGND.
[0036] Preferably, the resistor R2, the resistor R3 and the resistor R64 are chip resistors.
[0037] Preferably, if Figure 1 As shown, a first test point 11 and a second test point 12 are provided.
[0038] Preferably, the current limiting chip U4 is a 7803 current limiting chip.
[0039] The 7803 current limiting chip is a PMU (power management unit) that highly integrates a load switch and a low-noise low-dropout (LDO) regulator. The input voltage range of the input pin VIN is 5-16V. The maximum input voltage of the 7803 can reach 28V without damage. The load switch can support an output current of up to 630mA, and the LDO can provide an output current of 50Ma. The output voltage can be adjusted. The output pin OUT is the output pin of the load switch. The feedback pin FB detects the output voltage of the LDO, which is adjusted to 1.1V by the control loop. A resistor divider is connected to the feedback pin FB; the output pin LDOOUT is the output pin of the LDO regulator voltage. The setting pin ISET is the current limit setting pin. The current limit of the load switch is programmed by connecting a resistor R3 between the setting pin ISET pin and the ground terminal MKGND. When the setting pin ISET is short-circuited to ground, the current limit is 630mA (minimum).
[0040] like Figure 2 As shown, the 7803 current limiting chip has two built-in N-MOSFET output transistors to provide low on-resistance for low voltage dropout applications. The 7803 chip contains two independent current limiting circuits that detect and control the gate voltage of the pass tube to limit the output current to a certain value. If the dropout voltage of the load switch is lower than the set value, the current limit value decreases as the dropout voltage increases, thereby preventing equipment damage and over-temperature protection. The current limit of the load switch can be programmed by the setting pin ISET, and the current limit value can be calculated by the following formula:
[0041]
[0042] I LIM (A): It is the current limit of the setting pin ISET of the current limiting chip U4;
[0043] R SET (KΩ): is the resistance value of the resistor R3 connected in series between the setting pin ISET and the ground terminal MKGND;
[0044] The output voltage of the output pin LDOOUT can be designed by different resistor values. The reference voltage is calculated by 1.1V of the feedback pin FB. The calculation formula is as follows:
[0045]
[0046] VFF: represents the voltage value output by the output pin LDOOUT of the current limiting chip U4;
[0047] R64: is the resistance value of the resistor R64 between the output pin LDOOUT and the feedback pin FB;
[0048] R2: is the resistance value of the resistor R2 between the feedback pin FB pin and the ground terminal MKGND.
[0049] The 7803 current limiting chip integrates independent short-circuit protection. When the load switch is short-circuited, a large transient current may flow and the DC current limiting circuit responds. When the chip triggers the short-circuit protection, it will restart once to check whether the circuit exists. If the short-circuit state of the output pin OUT remains for more than 300ms, the power field effect tube is forced to turn off and enabled again after 3s. If the short-circuit state of the output pin LDOOUT remains for more than 70ms, the power field effect tube is forced to turn off and can be enabled again after 1s. Only if the short-circuit condition is not eliminated, the process is repeated.
[0050] The present invention is described above by way of examples, but the present invention is not limited to the above specific embodiments, and any changes or modifications based on the present invention belong to the scope of protection required by the present invention.
Claims
1. A current limiting protection circuit based on a current limiting chip, characterized in that: include: Resistor R2, resistor R64 and current limiting chip U4, the current limiting chip U4 includes an input pin VIN, a feedback pin FB, an output pin OUT and an output pin LDOOUT, one end of the resistor R2 is connected to the ground terminal MKGND, and the other end is connected to the feedback pin FB of the current limiting chip U4; one end of the resistor R64 is connected to the feedback pin FB of the current limiting chip U4 and the resistor R2, and the other end is connected to the output pin LDOOUT of the current limiting chip U4; the resistor R2 is connected to the ground terminal MKGND.
2. The current limiting protection circuit based on the current limiting chip according to claim 1, characterized in that: The capacitor C43 is also included. The capacitor C43 is connected in series between the input pin VIN of the current limiting chip U4 and the ground terminal MKGND.
3. The current limiting protection circuit based on the current limiting chip according to claim 1, characterized in that: It also includes a resistor R3. The current limiting chip U4 also includes a setting pin ISET. The resistor R3 is connected in series between the setting pin ISET of the current limiting chip U4 and the ground terminal MKGND. The setting pin ISET is used to limit current.
4. The current limiting protection circuit based on the current limiting chip according to claim 1, characterized in that: It also includes an aluminum electrolytic capacitor CP36, the positive electrode of the aluminum electrolytic capacitor CP36 is connected to the output pin LDOOUT of the current limiting chip U4, and the negative electrode of the aluminum electrolytic capacitor CP36 is connected to the ground terminal MKGND.
5. The current limiting protection circuit based on the current limiting chip according to claim 4, characterized in that: A capacitor C64 is also included, and the capacitor C64 is connected in parallel to both ends of the aluminum electrolytic capacitor CP36.
6. The current limiting protection circuit based on the current limiting chip according to claim 1, characterized in that: The current limiting chip U4 further includes a ground pin GND, and the ground pin GND is connected to the ground terminal MKGND.
7. The current limiting protection circuit based on the current limiting chip according to claim 3, characterized in that: The resistor R2, the resistor R3 and the resistor R64 are chip resistors.
8. The current limiting protection circuit based on the current limiting chip according to claim 1, characterized in that: The current limiting chip U4 is a 7803 current limiting chip.