Automatic switching system for power supply and standby power supply

Abstract

The utility model relates to the technical field of power supply systems, in particular to an automatic switching system for a power supply and a standby power supply, which is characterized by comprising a main power supply input part which comprises a transient voltage suppressor D93, a filter capacitor C450, a filter capacitor C452 and a PMOS (P-channel Metal Oxide Semiconductor) tube U39 and is used for receiving an external main power supply and carrying out anti-surge treatment and filtering energy storage; the standby power supply input part comprises a filter capacitor C456, a filter capacitor C454 and a PMOS tube U40 and is used for receiving a standby power supply and carrying out filtering and energy storage, and the standby power supply input part has the characteristics of simplicity, practicability and low cost, can effectively prevent reverse connection, power supply outage and poor contact, and has the functions of automatic switching, state detection and locking of the standby power supply.

Description

Technical Field

[0001] This application relates to the technical field of power systems, and particularly to an automatic switching system for a main power supply and a backup power supply. Background Art

[0002] In many electronic devices, the stability of the power system is crucial. For some application scenarios where sudden power interruption is not allowed, such as in-vehicle, industrial control, medical equipment, etc., once a power failure occurs, it may cause the device to fail to start, data loss, or even device damage.

[0003] Therefore, these devices are usually equipped with a backup power supply, and a solution that can automatically switch to the backup power supply when the main power supply fails is required. In addition, problems such as reverse power connection, power outage, and poor contact need to be solved to ensure the stable operation of the system. The purpose of this project is to develop an automatic switching system for a main power supply and a backup power supply to achieve this goal. Utility Model Content

[0004] In view of at least one of the above technical problems, this application provides an automatic switching system for a main power supply and a backup power supply, adopting the following technical solutions to solve the problems.

[0005] According to one aspect of this application, an automatic switching system for a main power supply and a backup power supply is provided, characterized in that it includes:

[0006] The main power input part, including a transient voltage suppressor D93, a filter capacitor C450, a filter capacitor C452, and a PMOS transistor U39, is used to receive an external main power supply and perform surge protection and filter energy storage;

[0007] The backup power input part, including a filter capacitor C456, a filter capacitor C454, and a PMOS transistor U40, is used to receive a backup power supply and perform filter energy storage;

[0008] The main power output control circuit, including a control transistor Q38, a resistor R342, and a resistor R343, is used to control the conduction between the main power input part and the output terminal;

[0009] The backup power output control circuit, including a diode D92, a resistor R342, and a resistor R343, is used to control the conduction between the backup power input part and the output terminal;

[0010] The status detection part, including a resistor R342 and a resistor R343, is used to detect the switching status between the main power supply and the backup power supply.

[0011] This application is further configured such that the main power input section is directly connected to the output terminal VBAT_S through the intrinsic diode of PMOS transistor U39. The drain of the PMOS transistor U39 is connected to the main power input section, and the gate is controlled by control transistor Q38, so that the PMOS transistor U39 conducts when the main power supply VBAT_IN is input.

[0012] This application is further configured such that one end of the transient voltage suppressor D93 is connected to the main power supply VBAT_IN, the other end of the transient voltage suppressor D93 is connected to ground, one end of the filter capacitor C450 is connected to the main power supply VBAT_IN, and the other end is connected to ground. One end of the filter capacitor C452 is connected to the main power supply VBAT_IN, and the other end is grounded.

[0013] This application is further configured such that the backup power input section is directly connected to the output terminal VBAT_S through the intrinsic diode of PMOS transistor U40. The drain of the PMOS transistor U40 is connected to the backup power supply V_LI input section, and the gate is controlled by diode D92 and resistors R342 and R343, so that the backup power supply V_LI PMOS transistor U40 conducts when the main power supply is powered off.

[0014] This application is further configured such that one end of the filter capacitor C456 in the backup power input section is connected to the backup power supply V_LI, and the other end is connected to ground;

[0015] One end of the filter capacitor C454 is connected to the backup power supply V_LI, and the other end is grounded;

[0016] The drain of the PMOS transistor U40 is connected to the common end of the filter capacitor C456 and the filter capacitor C454, and the source is connected to the output terminal VBAT_S.

[0017] This application is further configured such that resistors R342 and R343 in the main power output control circuit form a voltage dividing circuit for providing a bias voltage to control transistor Q38. When the main power supply VBAT_IN exists, control transistor Q38 conducts, causing the gate voltage of PMOS transistor U39 to be pulled low, so that the source-drain of PMOS transistor U39 conducts, and the main power supply VBAT_IN can be normally output.

[0018] This application is further configured such that resistors R342 and R343 and diode D92 in the backup power output control circuit together form a voltage dividing circuit for controlling the gate voltage of PMOS transistor U40. When the main power supply VBAT_IN is disconnected, through the voltage dividing action of diode D92, resistors R342 and R343, the gate voltage of PMOS transistor U40 approaches 0V, and then PMOS transistor U40 conducts, and the backup power supply V_LI is normally output.

[0019] This application is further configured such that in the state detection section, resistor R342 and resistor R343 form a voltage division network to generate an intermediate voltage VBAT_SW_EN by dividing the voltage of the main power supply VBAT_IN for state detection.

[0020] This application has the following technical effects:

[0021] This application is an automatic switching and policy control circuit for a main power supply and a backup power supply, featuring simplicity, practicality, and low cost. It can effectively prevent reverse connection, power outage, and poor contact, and has functions of automatic switching of the backup power supply, state detection, and locking. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art. Obviously, the drawings described below are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0023] Figure 1 is the circuit diagram of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To make the above objects, features, and advantages of this application more apparent and understandable, the following will provide a detailed description of the specific embodiments of this application with reference to the drawings. Many specific details are set forth in the following description to fully understand this application. However, this application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of this application. Therefore, this application is not limited by the specific embodiments disclosed below.

[0025] In this embodiment of this application, as Figure 1 shown, an automatic switching system for a main power supply and a backup power supply is provided.

[0026] Main power supply input section:

[0027] It enters from the main power supply VBAT_IN, passes through the transient voltage suppressor D93 to prevent surges, and is filtered and stored with energy by the filter capacitors C450 and C452 (these two capacitors are used to filter out high-frequency noise on the power line and store energy to maintain voltage stability). Then it enters the PMOS transistor U39 (U39 is a power field-effect transistor used to control the on and off of the power supply). The power supply can directly reach the output at VBAT_S through the intrinsic diode of the PMOS transistor U39 (there is an intrinsic diode inside the PMOS transistor. When the PMOS transistor is turned on, this diode forms a low-impedance path, allowing the power supply to be directly transmitted to the output terminal). The transient voltage suppressor D93 can select a suitable TVS tube to ensure that the system is protected from external voltage mutations. The selection of the filter capacitors C450 and C452 should consider the fluctuation range of the power supply and the load characteristics to ensure system stability.

[0028] Backup power input section:

[0029] The backup power supply V_LI is filtered and stored with energy by the filter capacitors C454 and C456 (the functions of these two capacitors are similar to those of the capacitors in the main power supply input section, used to filter out noise and store energy), and then enters the PMOS transistor U40. When and only when the voltage of the backup power supply V_LI is greater than the main power supply input VBAT_IN, the backup power supply V_LI can directly reach the output at VBAT_S through the intrinsic diode of the PMOS transistor U40 (U40 also has an intrinsic diode. When the voltage of the backup power supply is higher than the main power supply output, this diode will conduct, allowing the backup power supply to be transmitted to the output terminal).

[0030] Main power output control circuit:

[0031] The gate of the PMOS transistor U39 is controlled by the control transistor Q38, and the resistors R342 and R343 provide the bias voltage for the control transistor Q38 (the control transistor Q38 is used to control the on and off of the PMOS transistor U39). When the main power supply VBAT_IN is input, the bias voltage turns on the control transistor Q38. Therefore, the voltage of TP222 is 0V (TP222 is the detection point of the gate of U39. When the control transistor Q38 is turned on, the gate voltage of the PMOS transistor U39 is pulled down to nearly 0V), and then the source and drain of the PMOS transistor U39 are turned on (a conduction path is formed between the source and drain of the PMOS transistor U39), and the main power supply VBAT_IN outputs normally to supply power to the device (the main power supply VBAT_IN is transmitted to VBAT_S through the PMOS transistor U39 to provide stable power for the device).

[0032] Backup power output control circuit:

[0033] The diode D92 is used to control the conduction of the backup power supply. The resistors R342 and R343 provide the gate voltage for the PMOS transistor U40 (the gate voltage of the PMOS transistor U40 is controlled by the voltage division circuit formed by the diode D92, the resistor R342, and the resistor R343). When the input of the main power supply VBAT_IN is disconnected, the voltage of TP223 is approximately 0V (TP223 is the detection point of the gate of the PMOS transistor U40. When the main power supply VBAT_IN is disconnected, the gate voltage of the PMOS transistor U40 is pulled down to nearly 0V), thereby enabling the source-drain of the PMOS transistor U40 to conduct (a conduction path is formed between the source and the drain of the PMOS transistor U40), and the backup power supply V_LI outputs normally to supply power to the device (when the main power supply VBAT_IN is disconnected, the backup power supply V_LI is transmitted to VBAT_S through the PMOS transistor U40 to provide a stable power supply for the device).

[0034] Status detection section:

[0035] The resistors R342 and R343 divide the voltage of the main power supply VBAT_IN, and the output voltage VBAT_SW_EN is supplied for the detection device to monitor the voltage of the main power supply VBAT_IN. When it is detected that the voltage of VBAT_SW_EN = VBAT_IN x (R343 / (R342 + R343)), it is the state where the main power supply VBAT_IN outputs power supply (when the main power supply VBAT_IN supplies power normally, the voltage of VBAT_SW_EN is the voltage after voltage division, representing that the main power supply is supplying power). When it is detected that the voltage of VBAT_SW_EN = 0V, it is the state where the backup power supply V_LI outputs power supply (when the backup power supply V_LI supplies power, since the main power supply VBAT_IN has been disconnected, the voltage of VBAT_SW_EN drops to 0V). When it is detected that the voltage of VBAT_SW_EN jumps between VBAT_IN x (R343 / (R342 + R343)) and 0V, it is that the power supply output contact of the main power supply VBAT_IN is poor (when the contact of the main power supply VBAT_IN is poor, the voltage will fluctuate between the voltage division value of the main power supply VBAT_IN power supply voltage and 0V). According to the voltage state of this VBAT_SW_EN, the system makes management strategy control (by detecting the voltage state of VBAT_SW_EN, the system can judge the state of the power supply and take corresponding management measures).

[0036] Switching process between the main power supply and the backup power supply:

[0037] When the main power supply VBAT_IN is suddenly disconnected, the voltage of VBAT-S drops (after the main power supply VBAT_IN is disconnected, the voltage at the output terminal VBAT-S starts to drop). When the voltage of VBAT-S drops to a point where the standby power supply V_LI voltage is greater than the forward conduction voltage of the intrinsic diode of VBAT-S + VU40, the standby power supply V_LI conducts with VBAT-S (when the voltage of the standby power supply V_LI is higher than the output voltage plus the conduction voltage drop of diode D92, the standby power supply V_LI starts to supply power to the output terminal). At the same time, when the voltage of the main power supply VBAT_IN drops to a certain value, the PMOS transistor U40 conducts through diode D92, resistor R342, and resistor R343 (when the voltage of the main power supply VBAT_IN is not sufficient to maintain the conduction of PMOS transistor U39, the gate voltage of PMOS transistor U40 is pulled low through diode D92, resistor R342, and resistor R343, causing PMOS U40 to conduct). The standby power supply V_LI and VBAT-S conduct normally, and the automatic switching of the standby power supply V_LI is completed (at this time, the standby power supply supplies power to the output terminal VBAT-S through PMOS transistor U40).

[0038] The detection status diagram of VBAT_SW_EN and the normal operating conditions of each power supply are shown in Tables 1 and 2 as follows:

[0039]

[0040] Locking function:

[0041] When the main power supply VBAT_IN is suddenly disconnected or has poor contact, the voltage value at VBAT_SW_EN is different (when the main power supply VBAT_IN is disconnected, the voltage of VBAT_SW_EN becomes 0V, and when there is poor contact, the voltage fluctuates between 0V and the divided voltage value). By detecting the voltage value here, the power supply switching state can be effectively judged (by detecting the voltage state of VBAT_SW_EN, the switching situation of the power supply can be determined), and the input switching state of the main power supply VBAT_IN can be locked, solving the problem of unstable system power supply caused by poor contact (through the locking mechanism, when poor contact is detected, the input of the main power supply VBAT_IN can be locked to prevent power instability caused by poor contact).

[0042] The above is only the preferred embodiment of the present application, and it is not intended to limit the present application in any form. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present application. Therefore, all equivalent changes made according to the shape, structure, and principle of the present application without departing from the content of the technical solution of the present application should be covered within the protection scope of the present application.

Claims

1. An automatic switching system for a power supply and a backup power supply, characterized in that, Comprising: The main power input section, including a transient voltage suppressor D93, filter capacitors C450, C452, and a PMOS transistor U39, for receiving an external main power supply and performing surge protection and filtering and energy storage; The backup power input section, including filter capacitors C456, C454, and a PMOS transistor U40, for receiving a backup power supply and performing filtering and energy storage; The main power output control circuit, including a control transistor Q38, resistors R342 and R343, for controlling the conduction between the main power input section and the output terminal; The backup power output control circuit, including a diode D92, resistors R342 and R343, for controlling the conduction between the backup power input section and the output terminal; The state detection section, including resistors R342 and R343, for detecting the switching state between the main power supply and the backup power supply.

2. The automatic switching system of a power supply and a backup power supply according to claim 1, wherein: The main power input section is directly connected to the output terminal VBAT_S through the intrinsic diode of the PMOS transistor U39. The drain of the PMOS transistor U39 is connected to the main power input section, and the gate is controlled by the control transistor Q38, so that the PMOS transistor U39 conducts when the main power supply is input.

3. The automatic switching system of a power supply and a backup power supply according to claim 2, characterized in that: One end of the transient voltage suppressor D93 is connected to the main power supply, the other end is connected to ground. One end of the filter capacitor C450 is connected to the main power supply, and the other end is connected to ground. One end of the filter capacitor C452 is connected to the main power supply, and the other end is grounded.

4. The automatic switching system of a power supply and a backup power supply according to claim 1, characterized in that: The backup power input section is directly connected to the output terminal VBAT_S through the intrinsic diode of the PMOS transistor U40. The drain of the PMOS transistor U40 is connected to the backup power input section, and the gate is controlled by the diode D92, resistors R342 and R343, so that the PMOS transistor U40 conducts when the main power supply is powered off.

5. The automatic switching system of a power supply and a backup power supply according to claim 4, characterized in that: One end of the filter capacitor C456 in the backup power input section is connected to the backup power supply, and the other end is connected to ground; One end of the filter capacitor C454 is connected to the backup power supply, and the other end is grounded; The drain of the PMOS transistor U40 is connected to the common terminal of the filter capacitors C456 and C454, and the source is connected to the output terminal.

6. The automatic switching system of a power supply and a backup power supply according to claim 1, characterized in that: In the main power output control circuit, the resistors R342 and R343 form a voltage dividing circuit for providing a bias voltage to the control transistor Q38. When the main power supply exists, the control transistor Q38 conducts, causing the gate voltage of the PMOS transistor U39 to be pulled low, so that the source-drain of the PMOS transistor U39 conducts, and the main power supply can be normally output.

7. An automatic switching system for a power supply and a backup power supply according to claim 1, characterized in that: In the backup power output control circuit, the resistors R342 and R343 and the diode D92 together form a voltage dividing circuit for controlling the gate voltage of the PMOS transistor U40. When the main power supply is disconnected, through the voltage dividing action of the diode D92, resistors R342 and R343, the gate voltage of the PMOS transistor U40 approaches 0V, and then the PMOS transistor U40 conducts, and the backup power supply is normally output.

8. An automatic switching system for a power supply and a backup power supply according to claim 1, characterized in that: In the state detection section, resistor R342 and resistor R343 form a voltage division network to generate an intermediate voltage for state detection by dividing the voltage of the main power supply.

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