CN219999089U - Standby power supply switching circuit - Google Patents

Abstract

The utility model discloses a standby power supply switching circuit, which relates to the field of power supply switching, and is characterized in that: the power supply switching device comprises a voltage detection module, a power supply switching module and a controller, wherein the input end of the voltage detection module is connected with a main power supply, the output end of the voltage detection module is connected with the controller, the power supply switching module is connected with the main power supply and a standby power supply, and the controller is connected with the power supply switching module; the voltage detection module is used for detecting whether the voltage value of the main power supply is lower than a set voltage threshold value or not, and outputting a level signal when the voltage value is lower than the voltage threshold value; and the controller is used for controlling the power supply switching module to switch the power output of the main power supply and the standby power supply when receiving the level signal so as to supply power to the load. The utility model avoids the condition that the MOS tube is adopted as a switching element in the prior art, and the main power supply charges the standby power supply easily in the switching process.

Description

Standby power supply switching circuit

Technical Field

The utility model relates to the field of power supply switching, in particular to a standby power supply switching circuit.

Background

Backup batteries are provided on many devices. The system can be switched to a standby battery to supply power for the system after external power failure, so that the work after power failure is performed after the external power failure, such as storing some key information, is facilitated. The circuit design of the spare battery of the equipment is an important part in the whole design of the equipment, and the relation is that whether the equipment can work normally after the equipment system is powered down.

The main problems existing at present are: 1) If the main power supply and the standby power supply adopt MOS tubes as switching components, the situation that the main power supply charges the standby power supply is easily caused in the switching process; 2) If the main power supply and the standby power supply adopt diodes as switching devices, the voltage drop of the diodes themselves causes the reduction of the power supply voltage of the later stage and the consumption of part of electric energy on the diodes; 3) In the production and manufacture, the standby power supply can be arranged on the equipment in advance, but the standby power supply can supply power to the whole equipment at the moment, the electric quantity of the standby power supply can be discharged in advance due to the limited capacity of the standby power supply, and if the electric quantity is discharged all the time, the service capacity and the service life of the standby power supply can be reduced; 4) The switching judgment basis of the main power supply and the standby power supply is that the main power supply is reduced to a threshold value, if the main power supply is unstable, the main power supply and the standby power supply are frequently switched, so that the instability of the whole equipment and the service life attenuation of a switching device are caused.

Disclosure of Invention

In order to solve at least one of the disadvantages of the prior art, the utility model provides a standby power supply switching circuit, which detects whether the voltage values of a main power supply and a standby power supply are lower than a set voltage threshold value through a voltage detection module, outputs a level signal when the voltage values are lower than the voltage threshold value, then receives the level signal output by a voltage control module through a mode that a controller (MCU) is connected with the voltage detection module, and controls the power supply switching module to switch the power supply of a load based on the height of the level signal, thereby avoiding the condition that the main power supply charges the standby power supply easily in the switching process by adopting an MOS (metal oxide semiconductor) tube as a switching element in the prior art.

The technical aim of the utility model is realized by the following technical scheme:

the utility model provides a standby power supply switching circuit which comprises a main power supply, a standby power supply, a voltage detection module, a power supply switching module and a controller, wherein the input end of the voltage detection module is connected with the main power supply, the output end of the voltage detection module is connected with the controller, the power supply switching module is connected with the main power supply and the standby power supply, and the controller is connected with the power supply switching module;

the voltage detection module is used for detecting whether the voltage value of the main power supply is lower than a set voltage threshold value or not, and outputting a level signal when the voltage value is lower than the voltage threshold value;

and the controller is used for controlling the power supply switching module to switch the power output of the main power supply and the standby power supply when receiving the level signal so as to supply power to the load.

In one implementation, the power switching module includes a main power control module and a standby power control module; the main power supply control module is respectively connected with the main power supply, the voltage detection module, the load and the controller; the standby power supply control module is respectively connected with the standby power supply, the voltage detection module, the load and the controller;

the controller is also used for controlling the working states of the main power supply control module and the standby power supply control module so that the power supply of the load is switched from the main power supply to the standby power supply or from the standby power supply to the main power supply.

In one implementation scheme, the main power supply control module comprises a power supply enabling module and a power supply conversion module, wherein the input end of the power supply enabling module is connected with the voltage detection module, the output end of the power supply enabling module is connected with the power supply conversion module, and the output end of the main power supply is connected with the input end of the power supply conversion module;

the power supply enabling module is controlled by the level signal output by the voltage detection module and the control signal output by the controller so as to enable the power supply conversion module to be on or off;

the power conversion module is used for increasing or decreasing the output voltage of the main power supply.

In one implementation scheme, the power supply enabling module comprises a MOS tube Q31, a resistor R32 and a resistor R33;

one end of the resistor R33 is connected with the voltage detection module, and the other end of the resistor R is connected with the grid electrode of the MOS tube Q31;

the drain electrode of the MOS tube Q31 is connected with the resistor R31 and the resistor R32 respectively, and the resistor R31 and the resistor R32 are connected.

In one implementation, the power conversion module is a DC-DC circuit, the Vin end of the DC-DC circuit is connected to the main power supply, the EN end of the DC-DC circuit is connected to the common end of the connections to the resistor R31 and the resistor R32, and the Vout end of the DC-DC circuit is connected to the load.

In one implementation scheme, the standby power supply control module comprises a switching device and a switching device control module, wherein the input end of the switching device control module is connected with the voltage detection module and the controller, the output end of the switching device control module is connected with the switching device, and the output end of the switching device is connected with the load;

the switching device control module is controlled by the level signal output by the voltage detection module and the control signal output by the controller, so that the switching device control module is in a non-working state or a working state, the switching device is controlled to be turned on and off, and the switching device is used for switching the load supplied by the standby power supply.

In one implementation scheme, the switching device comprises a MOS tube Q21, a resistor R21 and a resistor R22, wherein one end of the resistor R21 is connected with a source electrode of the MOS tube Q21, and the other end of the resistor R21 is connected with a grid electrode of the MOS tube Q21 and the resistor R22 in parallel.

In one implementation scheme, the switch control module comprises a MOS tube Q22, a MOS tube Q23, a resistor R23 and a resistor R24;

the resistor R23 is connected with the grid electrode of the MOS tube Q22, the resistor R24 is connected with the grid electrode of the MOS tube Q23, and the source electrode of the MOS tube Q22 is connected with the drain electrode of the MOS tube Q23;

the drain electrode of the MOS tube Q22 is connected with the resistor R22, and the source electrode of the MOS tube Q23 is grounded.

In one implementation scheme, the switching circuit further comprises a first voltage acquisition module and a second voltage acquisition module, wherein the input end of the first voltage acquisition module is connected with a main power supply, and the output end of the first voltage acquisition module is connected with a controller; the input end of the second voltage acquisition module is connected with a standby power supply, and the output end of the second voltage acquisition module is connected with the controller;

the first voltage acquisition module is used for acquiring a first voltage signal of the main power supply;

the second voltage acquisition module is used for acquiring a second voltage signal of the standby power supply;

the first voltage signal of the main power supply, the second voltage signal of the standby power supply and the level signal output by the voltage detection circuit are received.

In one implementation scheme, the voltage detection module comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a MOS tube Q11, a MOS tube Q12 and a MOS tube Q13;

the resistor R12 and the resistor R13 are connected with the grid electrode of the MOS tube Q11 in parallel, and the resistor R11 is connected with the drain electrode of the MOS tube Q11;

the source of the MOS tube Q11 is connected with the drain of the MOS tube Q12, the source of the MOS tube Q12 is grounded, the grid of the MOS tube Q12 is connected with the drain of the MOS tube Q13, the resistor R15 is connected in parallel between the grid of the MOS tube Q12 and the drain of the MOS tube Q13, the resistor R14 is connected with the drain of the MOS tube Q13, the source of the MOS tube Q13 is grounded, and the resistor R16 and the resistor R17 are connected with the grid of the MOS tube Q13 in parallel.

Compared with the prior art, the utility model has the following beneficial effects:

1. the utility model detects whether the voltage values of the main power supply and the standby power supply are lower than the set voltage threshold value through the voltage detection module, outputs a level signal when the voltage values are lower than the voltage threshold value, then receives the level signal output by the voltage control module through a mode that the controller (MCU) is connected with the voltage detection module, and controls the power supply switching module to switch the power supply of the load based on the height of the level signal, thereby avoiding the condition that the main power supply charges the standby power supply easily in the switching process by adopting the MOS tube as a switching element in the prior art.

2. The voltage detection module is controlled by the controller, so that the problems of unstable system caused by frequently switching the switching device and damage caused by frequently opening and closing the switching device when the voltage of the main power supply is near a set voltage threshold value are solved.

3. The control module of the switching device is controlled by the MCU controller, and solves the problem that the standby power supply is used in advance caused by production and assembly and the problem of overdischarge when the standby power supply is in a low-power state through the control of the controller.

4. The utility model uses the voltage detection module to control the working state of the power supply enabling module, thereby achieving the effect of controlling the power supply conversion module to supply or cut off power to the load, and not adding additional switching devices, thereby simplifying the whole structure of the switching circuit.

Drawings

The accompanying drawings, which are included to provide a further understanding of embodiments of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model. In the drawings:

FIG. 1 is a schematic block diagram of a standby power switching circuit according to an embodiment of the present utility model;

fig. 2 is a schematic diagram of an overall structure of a standby power switching circuit according to an embodiment of the present utility model;

FIG. 3 is a circuit diagram of a voltage detection module according to an embodiment of the present utility model;

fig. 4 is a circuit diagram of a switching device included in a standby power control module according to an embodiment of the present utility model and a switching device control module connected to each other;

FIG. 5 is a circuit diagram of a connection between a power enabling module and a power converting module included in a main power control module according to an embodiment of the present utility model;

fig. 6 is a circuit diagram of a connection between a controller and a power switching module and between the controller and a voltage detection module according to an embodiment of the present utility model;

Detailed Description

For the purpose of making apparent the objects, technical solutions and advantages of the present utility model, the present utility model will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present utility model and the descriptions thereof are for illustrating the present utility model only and are not to be construed as limiting the present utility model.

It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly or indirectly connected to the other element. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.

As described in the background art, the main problems in the switching process of the main power supply and the standby power supply are as follows: 1) If the MOS tube is adopted as a switching element, the situation that the main power supply charges the standby power supply is easily caused in the switching process; 2) If the main power supply and the standby power supply adopt diodes as switching devices, the voltage drop of the diodes themselves causes the reduction of the power supply voltage of the later stage and the consumption of part of electric energy on the diodes; 3) In the production and manufacture, the standby power supply can be arranged on the equipment in advance, but the standby power supply can supply power to the whole equipment at the moment, the electric quantity of the standby power supply can be discharged in advance due to the limited capacity of the standby power supply, and if the electric quantity is discharged all the time, the service capacity and the service life of the standby power supply can be reduced; 4) The switching judgment basis of the main power supply and the standby power supply is that the main power supply is reduced to a threshold value, if the main power supply is unstable, the main power supply and the standby power supply are frequently switched, so that the instability of the whole equipment and the service life attenuation of a switching device are caused.

In order to solve the above-mentioned shortcomings of the background art, the present embodiment provides a standby power supply switching circuit, which detects whether the voltage value of the main power supply is lower than a set voltage threshold value through a voltage detection module, outputs a level signal when the voltage value is lower than the set voltage threshold value, then receives the level signal output by a voltage control module through a mode that a controller (MCU) is connected with the voltage detection module, and controls the power supply switching module to switch the power supply of the load based on the high-low part of the level signal, thereby avoiding the situation that in the prior art, an MOS tube is used as a switching element, and the main power supply charges the standby power supply easily in the switching process.

Here, the standby power supply switching circuit provided in this embodiment may be applied to standby power supply of terminal devices (such as mobile phones, computers, ipad, MP3, etc.), and may also be applied to switching of standby power supply of an elevator system, which will not be described further herein.

Referring to fig. 1, fig. 1 is a schematic diagram of an overall structure of a standby power supply switching circuit according to an embodiment of the present utility model, as shown in fig. 1, the standby power supply switching circuit includes a main power supply and a standby power supply, and further includes a voltage detection module, a power supply switching module, and a controller, where an input end of the voltage detection module is connected to the main power supply, an output end of the voltage detection module is connected to the controller, the power supply switching module is connected to the main power supply and the standby power supply, and the controller is connected to the power supply switching module;

the voltage detection module is used for detecting whether the voltage value of the main power supply is lower than a set voltage threshold value or not, and outputting a level signal when the voltage value is lower than the voltage threshold value;

and the controller is used for controlling the power supply switching module to switch the power output of the main power supply and the standby power supply when receiving the level signal so as to supply power to the load.

As shown in fig. 1, in this embodiment, the detection of the voltages of the main power supply and the standby power supply is implemented by using the detection principle of the voltage detection module, and the voltage required by the normal operation of the terminal device is used as the threshold standard for detection, so that it can be simply determined whether the current voltage of the power supply can meet the power requirement of the terminal device.

Accordingly, after the level signal is output, the controller (i.e. the MCU) outputs a corresponding signal through a corresponding pin to realize automatic switching of the power switching module, and as known to those skilled in the art, the standby power switching circuit of the present embodiment is essentially a power electronic technology, and accordingly, it is common knowledge that the pins of the controller are connected with the circuit elements of each circuit module.

Here, as a person skilled in the art, the controller is integrated on a circuit board of the load, so as to conveniently control the main power supply and the standby power supply to supply or stop supplying power to the load under the condition that the power is not available.

Therefore, the standby power supply switching circuit detects whether the voltage values of the main power supply and the standby power supply are lower than a set voltage threshold value or not through the voltage detection module, outputs a level signal when the voltage values are lower than the voltage threshold value, then receives the level signal output by the voltage control module through a mode that a controller (MCU) is connected with the voltage detection module, and controls the power supply switching module to switch the power supply of the load based on the height of the level signal, so that the condition that the main power supply charges the standby power supply easily in the switching process due to the fact that an MOS tube is used as a switching element in the prior art is avoided.

In one embodiment, the power switching module includes a main power control module and a standby power control module; the main power supply control module is respectively connected with the main power supply, the voltage detection module, the load and the controller; the standby power supply control module is respectively connected with the standby power supply, the voltage detection module, the load and the controller;

the controller is also used for controlling the working states of the main power supply control module and the standby power supply control module so that the power supply of the load is switched from the main power supply to the standby power supply or from the standby power supply to the main power supply.

Further, the main power supply control module comprises a power supply enabling module and a power supply conversion module, wherein the input end of the power supply enabling module is connected with the voltage detection module, the output end of the power supply enabling module is connected with the power supply conversion module, and the output end of the main power supply is connected with the input end of the power supply conversion module; the power supply enabling module is controlled by the level signal output by the voltage detection module and the control signal output by the controller so as to enable the power supply conversion module to be on or off; the power conversion module is used for increasing or decreasing the output voltage of the main power supply.

In one embodiment, the standby power supply control module comprises a switching device and a switching device control module, wherein the input end of the switching device control module is connected with the voltage detection module and the controller, the output end of the switching device control module is connected with the switching device, and the output end of the switching device is connected with the load; the switching device control module is controlled by the level signal output by the voltage detection module and the control signal output by the controller, so that the switching device control module is in a non-working state or a working state, the switching device is controlled to be turned on and off, and the switching device is used for switching the load supplied by the standby power supply.

In the above embodiment, as shown in fig. 2, the switching circuit provided in this embodiment includes the following components: the device comprises a main power supply, a voltage detection circuit, a switching device control module, a main power supply control module, a standby power supply, a first voltage acquisition module, a second voltage acquisition module and a load. The load includes a controller. The main power supply is an external power supply. The main power supply control module comprises a power supply enabling module and a power supply conversion module, wherein the power supply conversion module is used for supplying power to a load after reducing or boosting the main power supply. The power supply enabling module controls the power supply conversion module to enable output, and meanwhile, the power supply enabling module is controlled by an output signal of the voltage detection module.

The voltage detection module is used for detecting whether the voltage Vmean of the main power supply is lower than a set voltage threshold Vth1 or not, and simultaneously inputting control signals to the power supply enabling module, the switching device control module and the controller. The voltage detection module is powered by the standby battery and is controlled by the controller. The switching device control module is used for controlling the switching device to be turned on and off, and is controlled by a controller or other power sources. The switching device is used as a power supply switch of the standby power supply, and the PMOS tube or the NMOS tube is selected as the switching device instead of the diode, so that the problems of low power supply voltage of the rear stage and partial power consumption on the diode caused by voltage drop of the diode are avoided. The standby battery, the standby battery group and the like can be used as standby power supplies after the main power supply is powered down. The first voltage acquisition module and the second voltage acquisition module acquire voltages of a main power supply and a standby power supply respectively. The load is the total load of the rear stage of the terminal equipment or the chip and the like, and the terminal equipment comprises a controller which is used for controlling a voltage detection module and a switching device control module and is also used for receiving a first voltage signal of a main power supply, a second voltage signal of a standby power supply and a level signal output by the voltage detection module.

As shown in fig. 2 to 6, the working principle of the standby power switching circuit provided in this embodiment is as follows:

first, parameters of a switching circuit are set: when the enabling signal of the power enabling module is at a low level, the enabling signal of the switching device control module is at a high level, and the same principle is the opposite, namely that the enabling signals of the power enabling module and the switching device control module are mutually exclusive. As will be appreciated by those skilled in the art, the enable signal resembles a trigger signal, primarily a switch to ensure proper operation of the circuit or device, i.e., a function in the IC circuit may be turned on or off by this signal.

The voltage detection circuit determines that the voltage Vmain of the main power supply is equal to or greater than the voltage threshold Vth1 and outputs a low level, and when Vmain is less than Vth1, outputs a high level. The switching device control module is enabled when the controller outputs a high level.

When a terminal device or a system is powered, the following situations can occur, and the switching principle brought by each situation is different, specifically as follows:

1) When the main power supply is powered for the first time normally, namely the main power supply voltage Vmain is not less than Vth1, the voltage detection module outputs a low level to enable the power supply enabling module, and then the power supply conversion module supplies power to the load, so that the controller outputs a high level to the switching device control module. Thereby the switching device control module is in an operating state.

2) When the power is normally supplied, namely the main power voltage Vmain is not less than Vth1, the voltage detection module outputs a low level, the power supply enabling module and the switching device control module are disabled, so that the power supply conversion module supplies power to a system load, and the standby battery is disconnected from supplying power to the system load.

3) When the main power supply is under-voltage, namely Vmain is smaller than Vth1, the voltage detection module outputs high level, the switching device control module is enabled, the power supply enabling module is disabled, the power supply conversion module is turned off, the switching device is turned on, and the standby power supply supplies power to a system load.

4) When the voltage of the main power supply is higher than or lower than the Vdeta value, the control right of the power supply detection module is released, so that the damage caused by the frequent switching on or off of the switching device and the unstable system caused by the frequent switching of the power supply are prevented.

5) When vmain=0 and the standby power is connected, that is, the main power is not powered on, the voltage detection module outputs a high level because Vmain is less than Vth 1. But the controller is not electrified at this time, the level signal output to the switching device control module by the controller is low level, and the switching device control module is in a non-working state. The voltage detection module outputs a high level to enable the switching device control module, but the switching device cannot be opened because the switching device control module is in a non-working state, so that the standby power supply cannot supply power to the load.

6) When the voltage Vback up of the standby power supply is detected to be less than the voltage threshold Vth2, the controller outputs a low level to the switching device control module, so that the switching device control module is in a non-working state, the switching device is further closed, finally, the standby power supply is cut off to supply power to a load, the whole terminal equipment is powered off, and the problem that the battery of the standby power supply is not overdischarged to cause the battery capacity damage is solved.

As shown in fig. 5, in one embodiment, the power supply enabling module includes a MOS transistor Q31, a resistor R32, and a resistor R33; one end of the resistor R33 is connected with the voltage detection module, and the other end of the resistor R is connected with the grid electrode of the MOS tube Q31; the drain electrode of the MOS tube Q31 is connected with the resistor R31 and the resistor R32 respectively, and the resistor R31 and the resistor R32 are connected.

In a further embodiment, as shown in fig. 5, the power conversion module is a DC-DC circuit, the Vin terminal of the DC-DC circuit is connected to the main power supply, the EN terminal of the DC-DC circuit is connected to the common terminal connected to the resistor R31 and the resistor R32, and the Vout terminal of the DC-DC circuit is connected to the load.

As shown in fig. 5, when the detection_out is at a high level, the MOS transistor Q31 is turned on, the voltage division value of the resistor R31 and the resistor R32 is at a low level, at this time, the power supply module is disabled and does not output electric energy to the outside, when the detection_out is at a low level, the MOS transistor Q31 is in an off state, the voltage division value of the resistor R31 and the resistor R32 is at a high level, and the power supply conversion module is in an enabling state and starts outputting electric energy to the load. In this embodiment, the power conversion module is a DC-DC circuit, and the DC-DC chip has various options, such as TPS54540 bqdddarq 1 of TI.

As shown in fig. 4, the switching device includes a MOS transistor Q21, a resistor R21, and a resistor R22, where one end of the resistor R21 is connected to the source of the MOS transistor Q21, and the other end is connected to the gate of the MOS transistor Q21 and the resistor R22 in parallel.

In a further embodiment, the switch control module includes a MOS transistor Q22, a MOS transistor Q23, a resistor R23, and a resistor R24; the resistor R23 is connected with the grid electrode of the MOS tube Q22, the resistor R24 is connected with the grid electrode of the MOS tube Q23, and the source electrode of the MOS tube Q22 is connected with the drain electrode of the MOS tube Q23; the drain electrode of the MOS tube Q22 is connected with the resistor R22, and the source electrode of the MOS tube Q23 is grounded.

Specifically, the switching device is a MOS transistor Q21, and the MOS transistor Q21 may be a PMOS power transistor or an NMOS power transistor, which can withstand a large current.

The Control module of the switching device mainly comprises a MOS tube Q22 and a MOS tube Q23, when the detection_out and the Control2 are both high level, the MOS tube Q22 and the MOS tube Q23 are conducted, the drain level of the MOS tube Q22 is low level, and at the moment, the MOS tube Q21 is conducted due to the voltage division effect of the resistor R21 and the resistor R22. Control2 is a Control signal of the controller, when Control2 is at a low level, the MOS transistor Q22 is not conducted no matter the detection_out is at a high level or a low level, and the MOS transistor Q21 is also not conducted; when Control2 is high, and when detect_out is high, the MOS transistor Q22 is turned on, the MOS transistor Q21 is turned on, and when detect_out is low, the MOS transistor Q22 is turned off, and the MOS transistor Q21 is turned off.

In one embodiment, the switching circuit further comprises a first voltage acquisition module and a second voltage acquisition module, wherein the input end of the first voltage acquisition module is connected with a main power supply, and the output end of the first voltage acquisition module is connected with the controller; the input end of the second voltage acquisition module is connected with a standby power supply, and the output end of the second voltage acquisition module is connected with the controller; the first voltage acquisition module is used for acquiring a first voltage signal of the main power supply; the second voltage acquisition module is used for acquiring a second voltage signal of the standby power supply; the first voltage signal of the main power supply, the second voltage signal of the standby power supply and the level signal output by the voltage detection circuit are received.

In this embodiment, the working principles and circuit structures of the first voltage acquisition module and the second voltage acquisition module for implementing voltage acquisition are implemented by adopting the prior art, for example, as shown in fig. 6, the controller circuit in fig. 6 is a part of a system load, after the main power supply Vmain is divided by the resistor R41 and the resistor R42, the main power supply Vmain is output to the ADC1 of the controller, after the standby power supply Vbackup is divided by the resistor R43 and the resistor R44, the standby power supply Vbackup is output to the ADC2 of the controller, the resistor R41 and the resistor R42 form the first voltage acquisition module ADC1, the resistor R43 and the resistor R44 form the second voltage acquisition module ADC2, and the ADC1 and the ADC2 acquire the voltages of Vmain and Vbackup respectively. After the detection_out is reversely conducted through the resistor R46, the MOS tube Q41 and the resistor R47, the detection_out signal is input to an input pin of the controller, the controller detects whether the detection_out signal is used for monitoring whether two power supplies of the main power supply and the standby battery supply power to a system load or not, if the detection_out signal is frequently changed, the standby battery is fixed through the Control1 pin Control voltage detection module to supply power to the system load. The Control2 pin is used to enable the switching device Control module to turn on the backup power supply to power the tethered load.

In one embodiment, the voltage detection module includes a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a MOS transistor Q11, a MOS transistor Q12, and a MOS transistor Q13; the resistor R12 and the resistor R13 are connected with the grid electrode of the MOS tube Q11 in parallel, and the resistor R11 is connected with the drain electrode of the MOS tube Q11; the source of the MOS tube Q11 is connected with the drain of the MOS tube Q12, the source of the MOS tube Q12 is grounded, the grid of the MOS tube Q12 is connected with the drain of the MOS tube Q13, the resistor R15 is connected in parallel between the grid of the MOS tube Q12 and the drain of the MOS tube Q13, the resistor R14 is connected with the drain of the MOS tube Q13, the source of the MOS tube Q13 is grounded, and the resistor R16 and the resistor R17 are connected with the grid of the MOS tube Q13 in parallel.

As shown in fig. 3, in this embodiment, since the voltage detection module is configured to detect whether the voltage value of the main power supply is lower than the set voltage threshold, the voltage dividing circuit formed by the resistor R12 and the resistor R13 determines that the load is switched from the main power supply to the voltage threshold of the standby power supply.

In this embodiment, for example, as shown in fig. 3, fig. 3 is a circuit diagram of the voltage detection module provided in this embodiment, where a resistor R11, a resistor R12, a resistor R13, and a MOS transistor Q11 are core circuits for forming voltage detection, where a voltage division value of a voltage division circuit formed by the resistor R12 and the resistor R13 is a gate voltage of Q11, and a Control signal Control1 signal of the controller is divided by the resistor R17 and the resistor R16 to be supplied to a gate of the MOS transistor Q13, and then is transformed to be supplied to a gate of Q12. When Control1 is high level, the drain of the MOS transistor Q13 outputs low level, the MOS transistor Q12 is cut off, and whether the MOS transistor Q11 is on or not, the detection_out is high level; when Control1 is low, the drain of MOS transistor Q13 outputs high level, and MOS transistor Q12 is turned on, at this time, if Vmain is greater than or equal to Vth1, MOS transistor Q11 is turned on, and if Vmain is less than Vth1, MOS transistor Q11 is turned off, and if Vmain is less than Vth1, detection_out is outputted as high level.

Describing the character parameters appearing in the above embodiments, vmain represents the voltage of the main power supply, vbackup represents the voltage of the standby power supply, vsystem represents the voltage of the load power supply, and Vmcu represents the power supply voltage of the controller. Control signal: the detect_out represents a level signal output by the voltage detection module, the Control1 represents a first Control signal of the controller for locking a power supply of the load, and the Control2 represents an operation enabling signal of the controller output switching device Control module. The choice of the controller (MCU) is relatively large, such as a RH850 series singlechip for Ruisha, which is not described in detail.

After the above description of the circuit diagrams 3 to 6, the working principle of the standby power switching circuit provided in this embodiment is further described:

1) When power is normally supplied for the first time, namely the voltage Vmain of the main power supply is more than or equal to the voltage threshold Vth1, the Control1 defaults that the low-level MOS tube Q13 is not conducted, and the MOS tube Q12 is conducted due to the pull-up action of the resistor R14, so that the MOS tube Q11 is conducted, the detect_out is at a low level, the MOS tube Q31 is not conducted, the power conversion module is in an enabling state, and the output power supply supplies power to a load. Meanwhile, the control2 of the controller outputs high level to enable the switching device control module, so that the switching device control module is in a working state.

2) When the main power supply supplies power normally, namely the voltage Vmain of the main power supply is more than or equal to Vth1, detect_out is at a low level, the MOS tube Q22 is not conducted, so that the MOS tube Q21 is not conducted, and the standby power supply supplies power to the load.

3) When the main power supply is under voltage, namely when the voltage Vmain of the main power supply is smaller than the voltage threshold Vth1, the MOS tube Q11 is cut off, the detection_out output is in a high level, the MOS tube Q22 is conducted, the MOS tube Q21 is conducted, the standby power supply starts to supply power to a load, meanwhile, the MOS tube Q31 is conducted, the voltage division value of the resistor R31 and the resistor R32 is in a low level, the power supply conversion module is in an disabling state, and the power supply is stopped from outputting electric energy to the load.

4) When the voltage Vmain of the main power supply is unstable near the voltage threshold Vth1, the controller frequently receives the frequent high-low level change of the detect_out of the voltage detection module, at this time, the controller can set the control1 pin low, the MOS transistor Q12 is turned off, and the detect_out is high, at this time, the controller forces the standby power supply to supply power to the system load. When the controller detects that the voltage Vmain of the main power supply is higher or lower than the Vdeta value through the first voltage acquisition module ADC1, the control1 pin is set to be high level, and the function of the voltage detection module is restored.

5) When the voltage vmain=0v of the main power supply is connected to the standby power supply, that is, when the voltage Vbackup of the standby power supply is greater than 0, the voltage Vmain of the main power supply is less than the voltage threshold Vth1, and thus the detection_out is at a high level. However, at this time, vmcu=0v, and control2 is at a low level, MOS transistor Q23 is not turned on, MOS transistor Q21 is not turned on, and the standby power supply cannot supply power to the load.

6) When the standby battery supplies power, the controller detects the voltage of the standby power supply through the second voltage acquisition module ADC2, when the voltage Vbackground of the standby power supply is detected to be smaller than the voltage threshold Vth2, the control2 pin of the controller outputs a low level, so that the MOS tube Q21 is cut off, and finally the standby power supply is cut off to supply power to a load, so that the whole equipment is powered off.

The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the utility model, and is not meant to limit the scope of the utility model, but to limit the utility model to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the utility model are intended to be included within the scope of the utility model.

Claims (2)

1. The standby power supply switching circuit comprises a main power supply and a standby power supply, and is characterized by further comprising a voltage detection module, a power supply switching module and a controller, wherein the input end of the voltage detection module is connected with the main power supply, the output end of the voltage detection module is connected with the controller, the power supply switching module is connected with the main power supply and the standby power supply, and the controller is connected with the power supply switching module;

the voltage detection module is used for detecting whether the voltage value of the main power supply is lower than a set voltage threshold value or not, and outputting a level signal when the voltage value is lower than the voltage threshold value;

the controller is used for controlling the power supply switching module to switch the power output of the main power supply and the standby power supply when receiving the level signal so as to supply power to the load;

the power supply switching module comprises a main power supply control module and a standby power supply control module; the main power supply control module is respectively connected with the main power supply, the voltage detection module, the load and the controller; the standby power supply control module is respectively connected with the standby power supply, the voltage detection module, the load and the controller;

the controller is also used for controlling the working states of the main power supply control module and the standby power supply control module so that the power supply of the load is switched from the main power supply to the standby power supply or from the standby power supply to the main power supply;

the standby power supply control module comprises a switching device and a switching device control module, wherein the input end of the switching device control module is connected with the voltage detection module and the controller, the output end of the switching device control module is connected with the switching device, and the output end of the switching device is connected with the load;

the switching device control module is controlled by the level signal output by the voltage detection module and the control signal output by the controller, so that the switching device control module is in a non-working state or a working state, the switching device is controlled to be turned on and off, and the switching device is used for switching the load by the standby power supply;

the switching device comprises a MOS tube Q21, a resistor R21 and a resistor R22, wherein one end of the resistor R21 is connected with a source electrode of the MOS tube Q21, and the other end of the resistor R21 is connected with a grid electrode of the MOS tube Q21 and the resistor R22 in parallel;

the switching device control module comprises a MOS tube Q22, a MOS tube Q23, a resistor R23 and a resistor R24;

the resistor R23 is connected with the grid electrode of the MOS tube Q22, the resistor R24 is connected with the grid electrode of the MOS tube Q23, and the source electrode of the MOS tube Q22 is connected with the drain electrode of the MOS tube Q23;

the drain electrode of the MOS tube Q22 is connected with the resistor R22, and the source electrode of the MOS tube Q23 is grounded;

the main power supply control module comprises a power supply enabling module and a power supply conversion module, wherein the input end of the power supply enabling module is connected with the voltage detection module, the output end of the power supply enabling module is connected with the power supply conversion module, and the output end of the main power supply is connected with the input end of the power supply conversion module;

the power supply enabling module is controlled by the level signal output by the voltage detection module and the control signal output by the controller so as to enable the power supply conversion module to be on or off;

the power supply conversion module is used for increasing or decreasing the output voltage of the main power supply;

the power supply enabling module comprises a MOS tube Q31, a resistor R32 and a resistor R33;

one end of the resistor R33 is connected with the voltage detection module, and the other end of the resistor R is connected with the grid electrode of the MOS tube Q31;

the drain electrode of the MOS tube Q31 is respectively connected with the resistor R31 and the resistor R32, and the resistor R31 and the resistor R32 are connected;

the power conversion module is a DC-DC circuit, the Vin end of the DC-DC circuit is connected with the main power supply, the EN end of the DC-DC circuit is connected with the public end connected with the resistor R31 and the resistor R32, and the Vout end of the DC-DC circuit is connected with the load;

the switching circuit further comprises a first voltage acquisition module and a second voltage acquisition module, wherein the input end of the first voltage acquisition module is connected with a main power supply, and the output end of the first voltage acquisition module is connected with the controller; the input end of the second voltage acquisition module is connected with a standby power supply, and the output end of the second voltage acquisition module is connected with the controller;

the first voltage acquisition module is used for acquiring a first voltage signal of the main power supply;

the second voltage acquisition module is used for acquiring a second voltage signal of the standby power supply;

the first voltage signal of the main power supply, the second voltage signal of the standby power supply and the level signal output by the voltage detection circuit are received.

2. The standby power switching circuit according to claim 1, wherein the voltage detection module comprises a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a MOS transistor Q11, a MOS transistor Q12, and a MOS transistor Q13;

the resistor R12 and the resistor R13 are connected with the grid electrode of the MOS tube Q11 in parallel, and the resistor R11 is connected with the drain electrode of the MOS tube Q11;

the source of the MOS tube Q11 is connected with the drain of the MOS tube Q12, the source of the MOS tube Q12 is grounded, the grid of the MOS tube Q12 is connected with the drain of the MOS tube Q13, the resistor R15 is connected in parallel between the grid of the MOS tube Q12 and the drain of the MOS tube Q13, the resistor R14 is connected with the drain of the MOS tube Q13, the source of the MOS tube Q13 is grounded, and the resistor R16 and the resistor R17 are connected with the grid of the MOS tube Q13 in parallel.