Power supply protection circuit for high-speed digital circuit

Abstract

The invention provides a power supply protection circuit for a high-speed digital circuit, and belongs to the technical field of electronics and communication information. Comprising a current sensor and a voltage sensor which are arranged at a power inlet, and the voltage sensor and the current sensor are both connected with a microcontroller; a circuit passing through the current sensor and the voltage sensor is connected with an intermediate-stage filter circuit, the intermediate-stage filter circuit is connected with a power supply chip, and the power supply chip is connected with a final-stage filter circuit; the current sensor is used for carrying out parameter sampling on current and voltage, the microcontroller monitors the voltage and current conditions of an inlet and subsequent stages in real time, and the power supply chip is controlled stage by stage to ensure the safety of a power supply. According to the invention, the number of used devices is reduced, the cost is reduced, overvoltage and overcurrent risks are avoided, and finally the ripple noise of the power supply end of an electric device is reduced; a special filter circuit is added according to the characteristics of the switching power supply, and ripple introduction can be effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of electronics and communications, and in particular relates to a power protection circuit for high-speed digital circuits. Background Art

[0002] Electronic equipment in engineering often only accepts a simple one or several voltages supplied from the outside as power supply. At the same time, in order to reduce line losses, the power supply voltage is often more than tens of volts. However, the operating voltage of integrated circuits in circuit boards is mostly 5 volts or lower, which requires a dedicated power supply circuit for conversion. Depending on the different electrical devices, high-speed digital circuits mostly require multiple voltage rails for power supply. Common voltages include 5V, 3.3V, 1.8V, 1.2V, 0.8V, -5V, etc. Different voltage rails often face different problems. For example, 0.8V is mostly used for high-speed digital processing circuits, with large capacitive loads and prone to overcurrent during power-on and operation; -5V needs to be generated by an independent chip, which is prone to introduce ripples during the common ground process.

[0003] In view of the power supply abnormalities such as overvoltage, overcurrent, and excessive ripple that may occur in these circuits, there are independent solutions in the commonly used protection circuit designs, such as using a voltage comparator to control overvoltage, using a fuse to control overcurrent, and using a low-dropout linear regulator (LDO) to suppress ripple. However, each of them has its own disadvantages, mainly because it is difficult to strike a balance between cost and control accuracy. For example, when using an LDO chip to control ripple, due to the low power supply voltage and the problem of voltage drop, the power supply efficiency may only reach 40%-50%, and improving the efficiency requires increasing the intermediate power supply, which also brings about an increase in the number of devices and costs; and using a fuse to control overcurrent is often not accurate enough. If you want to control it accurately, you need to add sampling, comparison and control circuits. The present invention comprehensively plans the power supply protection circuit of the high-speed digital circuit, designs it for problems such as overvoltage, overcurrent, and excessive ripple, and finally realizes a low-cost integrated power supply protection circuit. Summary of the invention

[0004] The purpose of the present invention is to provide a power protection circuit for high-speed digital circuits, reduce the number of components used, reduce costs, avoid overvoltage and overcurrent risks, and ultimately reduce the ripple noise at the power supply end of the electrical device; adding a dedicated filter circuit according to the characteristics of the switching power supply can effectively reduce the introduction of ripple. The final ripple level is often only slightly lower than that of using an LDO chip, and can still meet the use requirements of most high-speed digital devices.

[0005] The above purpose is achieved through the following technical solutions: A power protection circuit for a high-speed digital circuit of the present invention comprises a current sensor and a voltage sensor arranged at a power input, wherein the voltage sensor and the current sensor are both connected to a microcontroller; the circuit after the current sensor and the voltage sensor is connected to an intermediate filter circuit, wherein the intermediate filter circuit is connected to a power chip, and the power chip is connected to a final filter circuit; the current sensor is used for sampling parameters of current and voltage, and the microcontroller monitors the input and subsequent voltage and current conditions at each level in real time, and controls the power chip step by step to ensure power safety.

[0006] Furthermore, the current sensor adopts a Hall sensor HCS724-30U.

[0007] Furthermore, the voltage sensor adopts a surge suppression dedicated chip SM4356MP.

[0008] Furthermore, the microcontroller adopts a microcontroller STM32F103 series with a built-in analog-to-digital converter.

[0009] Furthermore, the intermediate-stage filter circuit adopts a filter circuit in which an inductor and a capacitor are connected in parallel.

[0010] Furthermore, the final filter circuit is implemented by connecting a copper foil conductor in parallel with a capacitor C4 using a three-terminal capacitor equivalent circuit.

[0011] Beneficial Effects

[0012] 1. In order to solve the problems of overvoltage and overcurrent, the present invention uses a microcontroller with a built-in analog-to-digital converter and a current detection sensor to detect the power supply voltage and current at the entrance of the circuit board. The voltage detection is achieved by connecting the output of the subsequent power supply to the analog-to-digital converter pin of the microcontroller, and the current detection is achieved by a Hall sensor. The microcontroller is combined with the surge suppression chip SM4356MP and a single MOS tube to control the power input. The SM4356MP can clamp the input voltage to protect the subsequent circuit from overvoltage risks. At the same time, the microcontroller detects the working status and voltage conditions of the subsequent power chip, and uniformly controls the operation of the MOS and power chip, reducing the number of devices used, reducing costs, and avoiding overvoltage and overcurrent risks.

[0013] 2. For the problem of excessive ripple, considering the generation mechanism and transfer characteristics of power supply ripple, starting from the source, filter circuits are used step by step to reduce ripple transfer, and ripple suppression is added before and after the switching power supply chip. Common absorption filtering is used for step-by-step filtering, such as using LC circuits or magnetic beads as suppression methods, such as Figure 3 As shown, a three-terminal capacitor is used at the final output port to form a terminal filter circuit through layout and wiring and capacitor network coordination, as shown Figure 4As shown in the figure, the copper foil conductor part needs to adjust the copper foil conductor length, copper thickness, etc. according to parameters such as the circuit board material, and make full use of parasitic inductance to achieve the purpose of reducing devices, saving board area and filtering, and ultimately reduce the ripple noise at the power supply end of the electrical device.

[0014] 4. In view of the increase in ripple caused by the common ground of positive and negative electricity and the requirement for lower ripple of analog voltage, a similar dedicated filtering and single-point grounding design is adopted for the output of power supply chips with special voltages. The dedicated filtering circuit is still implemented by a combination of three-terminal capacitors, copper foil wires and inductors and capacitors. The single-point grounding is achieved by selecting appropriate ferrite beads. Adding a dedicated filtering circuit according to the characteristics of the switching power supply can effectively reduce the introduction of ripple. The final ripple level is often only slightly lower than that of using LDO chips, and can still meet the use requirements of most high-speed digital devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The power control block diagram proposed by the present invention; Figure 2 It is a schematic diagram of current and voltage sampling of the present invention; Figure 3 It is the commonly used LC absorption filter circuit of the intermediate stage of the present invention; Figure 4 It is a schematic diagram of the terminal filter circuit of the present invention. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted again that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0017] The present invention provides Figure 1 A power protection circuit for high-speed digital circuits shown in the figure includes a current sensor and a voltage sensor arranged at the power input, and the voltage sensor and the current sensor are both connected to a microcontroller; the circuit after the current sensor and the voltage sensor is connected to an intermediate-stage filter circuit, the intermediate-stage filter circuit is connected to a power chip, and the power chip is connected to a final-stage filter circuit; the current sensor is used to perform parameter sampling on current and voltage, and the microcontroller monitors the input and subsequent voltage and current conditions at each level in real time, and controls the power chip step by step to ensure power safety.

[0018] like Figure 2As shown, in this embodiment, the voltage parameters of the power input are sampled through the surge suppression dedicated chip SM4356MP, the input current is sampled through the Hall sensor HCS724-30U, and the output of each level of DCDC power supply is sampled through a microcontroller (STM32F103 series) with a built-in analog-to-digital converter; the sampling results of each level are taken, and if the voltage at the input is normal, the enable pin of the subsequent DCDC power chip on the high-speed digital circuit board is controlled by the microcontroller to perform unified power-on control. If the voltage output of the subsequent stage is abnormal after voltage sampling, the output of the corresponding power chip is turned off; the output of the DCDC power chip is set with a ripple control circuit step by step to reduce ripple transmission.

[0019] like Figure 3 As shown, the intermediate filter circuit in this embodiment adopts a step-by-step filter circuit to reduce ripple transmission, and adds ripple suppression before and after the switching power supply chip. The step-by-step filtering adopts common absorption filtering, for example, Figure 3 As shown, a filtering circuit in which an inductor L1 and a capacitor CI are connected in parallel is used before the power chip, and a filtering circuit in which an inductor L2 and a capacitor C2 are connected in parallel is used after the power chip.

[0020] like Figure 4 As shown, the final filter circuit in this embodiment is realized by connecting a copper foil wire in parallel with a capacitor C4 using a three-terminal capacitor equivalent circuit composed of inductors L3, L4, L5 and capacitor C3. The copper foil wire part in the figure needs to adjust the length and thickness of the copper foil wire according to parameters such as the circuit board material, and make full use of parasitic inductance to achieve the purpose of reducing components, saving board area and filtering, and ultimately reducing the ripple noise at the power supply end of the electrical device. In addition, in order to address the increased ripple caused by the common ground of positive and negative electricity and the lower ripple required for analog voltage, a similar dedicated filtering and single-point grounding design is adopted for the output power of the power chip with special voltage. The dedicated filtering circuit is still implemented using a combination of three-terminal capacitors, copper foil wires, and inductors and capacitors. The single-point grounding is achieved by selecting appropriate ferrite beads. Adding a dedicated filtering circuit according to the characteristics of the switching power supply can effectively reduce the introduction of ripple. The final ripple level is often only slightly lower than that of using an LDO chip, and can still meet the use requirements of most high-speed digital devices.

Claims

1. A power protection circuit for high-speed digital circuits, characterized in that: The power protection circuit for high-speed digital circuits comprises a current sensor and a voltage sensor arranged at a power input, wherein the voltage sensor and the current sensor are both connected to a microcontroller; the circuit after the current sensor and the voltage sensor is connected to an intermediate filter circuit, wherein the intermediate filter circuit is connected to a power chip, and the power chip is connected to a final filter circuit; the current sensor is used for parameter sampling of current and voltage, and the microcontroller monitors the input and subsequent voltage and current conditions at each level in real time, and controls the power chip step by step to ensure power safety.

2. A power protection circuit for high-speed digital circuits according to claim 1, characterized in that: The current sensor adopts the Hall sensor HCS724-30U.

3. A power protection circuit for high-speed digital circuits according to claim 1, characterized in that: The voltage sensor adopts the surge suppression dedicated chip SM4356MP.

4. A power protection circuit for high-speed digital circuits according to claim 1, characterized in that: The microcontroller adopts a microcontroller STM32F103 series with a built-in analog-to-digital converter.

5. The power protection circuit for high-speed digital circuits according to claim 1, characterized in that: The intermediate-stage filter circuit adopts a filter circuit in which an inductor and a capacitor are connected in parallel.

6. A power protection circuit for high-speed digital circuits according to claim 1, characterized in that: The final filter circuit is implemented by connecting a copper foil conductor in parallel with capacitor C4 using a three-terminal capacitor equivalent circuit.

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