Dual power supply circuit for gas meter

Abstract

The utility model discloses a kind of gas meter dual power supply circuit, integrated two-way battery power supply, voltage conversion circuit, sampling circuit, reference voltage circuit, comparator and power supply switching circuit. Through integrated hardware architecture, compatible 3.6V lithium battery and 6V dry battery two power supply modes simultaneously, two-way battery power supply is respectively accessed system, voltage conversion is carried out by voltage conversion circuit to adapt gas meter work. Sampling circuit real-time acquisition two-way battery voltage, and compare with reference voltage in comparator, to automatically, quickly complete the switching of power supply line, and this kind of pure hardware switching mechanism response speed reaches millisecond level, effectively avoid the compatibility and fault risk possibly brought by software logic, significantly improve the reliability of circuit. Integrated design saves the need of respectively for different power supply design independent circuit, simplify structure, reduce the quantity of component and PCB area occupation, substantially reduce hardware production cost and complexity.

Description

Technical Field

[0001] This utility model belongs to the technical field of gas meter power supply circuits, specifically a dual power supply circuit for gas meters. Background Technology

[0002] As a core metering instrument in both civilian and industrial sectors, the stability of the power supply system of gas meters directly determines the equipment's lifespan and operational reliability. Current gas meter power supply solutions mainly suffer from two types of problems: First, single power supply modes (such as relying solely on 3.6V lithium batteries or 6V dry cell batteries) have significant limitations in adaptability. While 3.6V lithium batteries offer advantages such as long battery life and stable voltage, their application is limited in some cost-sensitive scenarios. 6V dry cell batteries, while cheaper, suffer from large voltage fluctuations and short battery life, making it difficult to meet long-term stable power supply requirements. Second, existing dual-power supply gas meters often employ independent circuits and separate control architectures. This requires separate voltage conversion circuits, detection circuits, and control units for each power source, resulting in redundant PCB components and complex wiring. This not only significantly increases hardware production costs but also occupies more board space and is prone to compatibility issues between multiple circuits, reducing system reliability and increasing the probability of power supply switching failures.

[0003] To address the aforementioned issues, there is an urgent need for a highly integrated and simple dual power supply circuit solution. This solution should achieve compatibility and automatic switching between the two power supplies through an integrated hardware design, eliminating the need for multiple independent circuits, thereby simplifying the structure, reducing costs, and improving power supply stability. Utility Model Content

[0004] The purpose of this utility model is to provide a dual power supply circuit for gas meters to solve the problems mentioned in the background art, such as redundant power supply circuit structure, large number of components, high cost, and insufficient switching reliability of existing dual power supply gas meter power supply circuits.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] A dual-power supply circuit for a gas meter includes a battery power supply circuit, a voltage conversion circuit, a sampling circuit, a reference voltage circuit, a comparator circuit, and a power switching circuit; wherein,

[0007] The battery power circuit includes a first battery power circuit and a second battery power circuit, which provide main power supply and backup power supply respectively;

[0008] The voltage conversion circuit includes a first voltage conversion circuit and a second voltage conversion circuit, which convert the battery voltage into the system operating voltage, respectively.

[0009] The sampling circuit includes a first sampling circuit and a second sampling circuit, which perform voltage divider sampling on the two battery voltages respectively;

[0010] The reference voltage circuit provides a stable reference voltage;

[0011] The comparator circuit compares the sampled voltage with the reference voltage and outputs a switching control signal;

[0012] The power switching circuit selects the effective power supply path based on the control signal.

[0013] According to the above technical solution, the first battery power supply circuit includes power supply BT1, and the second battery power supply circuit includes power supply BT2; wherein, power supply BT1 is a 3.6V lithium battery, and power supply BT2 is a 6V dry cell battery.

[0014] The positive terminal of power supply BT1 is connected to the voltage conversion circuit, and the negative terminal of power supply BT1 is grounded; the positive terminal of power supply BT2 is connected to the voltage conversion circuit, and the negative terminal of power supply BT2 is grounded.

[0015] According to the above technical solution, the voltage conversion circuit includes a first voltage conversion circuit and a second voltage conversion circuit, the sampling circuit includes a first sampling circuit and a second sampling circuit, and the power switching circuit includes MOSFET Q1 and MOSFET Q2; wherein the first voltage conversion circuit is connected to the power supply BT1 of the first sampling circuit and the first battery power supply circuit and MOSFET Q1 respectively.

[0016] The second voltage conversion circuit is connected to the power supply BT2 of the second sampling circuit and the second battery power supply circuit, as well as the MOSFET Q2.

[0017] According to the above technical solution, the first voltage conversion circuit includes chip U2, inductor L1 and capacitor C3; the first sampling circuit includes resistor R1, resistor R2 and capacitor C1.

[0018] Pin 3 of chip U2 is connected to power supply BT1 and one end of resistor R1 respectively; pin 2 of chip U2 outputs a 5V standard operating voltage and is connected to one end of inductor L1, and the other end of inductor L1 is connected to capacitor C3 and pin 3 of MOSFET Q1 respectively; pin 3 of chip U2 is connected to pin 5 to realize power-on self-start.

[0019] Pin 1 of MOSFET Q1 is connected to the comparator circuit; pin 2 of MOSFET Q1 serves as the 5V standard operating voltage output terminal.

[0020] The other end of resistor R1 is connected to resistor R2, capacitor C1, and comparator circuit respectively;

[0021] Pin 1 of chip U2, the other end of resistor R2 and capacitor C1 are all grounded.

[0022] According to the above technical solution, the second voltage conversion circuit includes chip U3, inductor L2 and capacitor C4, and the second sampling circuit includes resistor R3, resistor R4 and capacitor C2.

[0023] Pin 3 of chip U3 is connected to power supply BT2 and one end of resistor R3; pin 2 of chip U3 outputs a 5V standard operating voltage and is connected to one end of inductor L2, and the other end of inductor L2 is connected to capacitor C4 and pin 3 of MOSFET Q2; pin 3 of chip U3 is connected to pin 5 to achieve power-on self-starting.

[0024] Pin 1 of MOSFET Q2 is connected to the comparator circuit; pin 2 of MOSFET Q2 serves as the 5V standard operating voltage output terminal.

[0025] The other end of resistor R3 is connected to resistor R4 and capacitor C2 respectively;

[0026] Pin 1 of chip U3, the other end of resistor R4 and capacitor C2 are all grounded.

[0027] According to the above technical solution, the reference voltage circuit includes resistor R5 and resistor R6; one end of resistor R5 is connected to the 5V standard working voltage, and the other end of resistor R5 is connected to the comparator circuit and resistor R6 respectively; the other end of resistor R6 is grounded.

[0028] According to the above technical solution, the comparator circuit includes comparator U4, resistors R7, R8, and R9, and transistor Q3; wherein, pin 3 of comparator U4 is connected to the first voltage conversion circuit; pin 2 of comparator U4 is connected to the reference voltage circuit; and pin 1 of comparator U4 is connected to pin 1 of MOSFET Q1, one end of resistor R9, and one end of resistor R7.

[0029] The other end of resistor R9 is connected to the 5V standard operating voltage, and the other end of resistor R7 is connected to pin 2 of transistor Q3; pin 1 of transistor Q3 is grounded; pin 3 of transistor Q3 is connected to one end of resistor R8 and pin 1 of MOSFET Q2.

[0030] The other end of resistor R8 is connected to the 5V standard operating voltage.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The circuit in this invention employs an integrated hardware architecture, simultaneously supporting both 3.6V lithium batteries and 6V dry cell batteries. This allows for the adaptation of multiple power inputs within a single circuit structure, effectively replacing the traditional approach of designing separate circuits for different power supplies. This integrated design significantly reduces the number of components and PCB area, resulting in a substantial reduction in hardware production costs.

[0033] Regarding the power supply switching mechanism, relying on the collaboration of the sampling circuit, reference voltage circuit, and comparator circuit, the system can autonomously complete the power supply mode switching at the hardware level without relying on software control logic. This pure hardware switching method reduces the response time to the millisecond level, effectively avoiding switching failures that may be caused by software compatibility issues, thereby significantly improving the reliability and stability of system operation. Attached Figure Description

[0034] Figure 1 This is a circuit diagram of the first battery power supply circuit, the first voltage conversion circuit, the first sampling circuit, and the switching circuit of this utility model.

[0035] Figure 2 This is a circuit diagram of the second battery power supply circuit, the second voltage conversion circuit, the second sampling circuit, and the switching circuit of this utility model.

[0036] Figure 3 This is a circuit diagram of the reference voltage circuit of this utility model;

[0037] Figure 4 This is a circuit diagram of the comparator circuit of this utility model. Detailed Implementation

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0039] Example 1

[0040] To achieve the above objectives, the power supply circuit for the gas meter in dual power supply mode provided by this utility model consists of a battery power supply circuit, a voltage conversion circuit, a sampling circuit, a reference voltage circuit, and a comparator circuit. Each functional module is connected by wires to form a complete power supply circuit. The specific structure and connection relationship of each module are as follows:

[0041] The battery power circuit, serving as the energy source for the entire power supply system, specifically provides operating power for the gas meter and includes a first battery power circuit and a second battery power circuit. For example... Figure 1 As shown, the first battery power supply circuit includes a power supply BT1, which is a 3.6V lithium battery. Its positive terminal is connected to the first voltage conversion circuit, and its negative terminal is directly grounded. Figure 2 As shown, the second battery power supply circuit includes power supply BT2, which is a 6V dry cell battery (composed of four 1.5V dry cell batteries connected in series). Its positive terminal is connected to the second voltage conversion circuit, and its negative terminal is grounded. The two battery circuits respectively undertake the main power supply and backup power supply functions, forming a complementary power supply system.

[0042] like Figure 1 and Figure 2 As shown, the voltage conversion circuit converts the output voltage of the two batteries into the standard operating voltage required by each power unit of the gas meter. The corresponding battery power supply circuit is divided into a first voltage conversion circuit and a second voltage conversion circuit. The sampling circuit focuses on real-time acquisition of the voltage signals from the two battery power supplies, providing accurate data support for switching control. It is also divided into a first sampling circuit and a second sampling circuit. The power switching circuit is responsible for executing the switching action of the power supply loop, including MOSFETs Q1 and Q2. These three components form a collaborative architecture of conversion, acquisition, and switching. Specifically, the first voltage conversion circuit establishes corresponding electrical connections with the first sampling circuit, the power supply BT1 of the first battery power supply circuit, and MOSFET Q1. The second voltage conversion circuit establishes corresponding electrical connections with the second sampling circuit, the power supply BT2 of the second battery power supply circuit, and MOSFET Q2, ensuring independent adaptation and precise control of each power supply.

[0043] like Figure 1As shown, the first voltage conversion circuit includes chip U2 (model TPS54302), inductor L1, and capacitor C3. The first sampling circuit consists of resistors R1 and R2, and capacitor C1. Pin 3 (VIN) of chip U2 forms a stable electrical connection with the positive terminal of power supply BT1. Pin 2 (SW) outputs a standard 5V operating voltage and is connected to one end of inductor L1. The other end of inductor L1 is connected to capacitor C3 and pin 3 (drain) of MOSFET Q1. Inductor L1 and capacitor C3 work together to achieve voltage filtering, ensuring stable output voltage. Pin 3 and pin 5 (EN) of chip U2 are directly connected. This connection method allows the first voltage conversion circuit to enter the enabled working state as long as it detects an input voltage from battery BT1. Its final output switching is controlled by MOSFET Q1, thus ensuring the independence and reliability of power supply switching control. Pin 1 (GND) of chip U2 is grounded to ensure the stability of circuit operation. The other end of resistor R1 is connected to resistor R2, capacitor C1, and comparator circuit to establish a multi-directional stable connection. The other ends of resistor R2 and capacitor C1 are grounded together to form a voltage divider filter circuit, which effectively filters out high-frequency interference in the voltage signal and ensures the stability of the sampling signal. Pin 1 (gate) of MOSFET Q1 is connected to comparator circuit to receive switching control signal, and pin 2 (source) serves as the 5V standard working voltage output terminal. Through the voltage conversion function of chip U2, the filtering effect of inductor L1 and capacitor C3, and the on / off control of MOSFET Q1, the stable output of BT1 voltage and the on / off control of the power supply circuit are realized.

[0044] like Figure 2As shown, the second voltage conversion circuit includes chip U3 (model TPS54302), inductor L2, and capacitor C4. The second sampling circuit consists of resistors R3 and R4, and capacitor C2. Pin 3 (VIN) of chip U3 forms a stable electrical connection with the positive terminal of power supply BT2. Pin 2 (SW) outputs a standard 5V operating voltage, and this pin is connected to one end of inductor L2. The other end of inductor L2 is connected to capacitor C4 and pin 3 (drain) of MOSFET Q2. Through the filtering effect of inductor L2 and capacitor C4, the 5V output voltage ripple is ensured to meet the requirements. Pin 3 and pin 5 (EN) of chip U3 are directly connected. This connection method allows the second voltage conversion circuit to enter the enabled working state as long as it detects an input voltage from battery BT2. Its final output switching is controlled by MOSFET Q2, thereby ensuring the independence and reliability of power supply switching control. Pin 1 (GND) of chip U3 is grounded. The other end of resistor R3 is stably connected to resistor R4, capacitor C2, and comparator circuit respectively. The other ends of resistor R4 and capacitor C2 are grounded together, which also realizes the voltage divider and filtering function to ensure the accuracy of the sampling signal. Pin 1 (gate) of MOSFET Q2 is connected to comparator circuit to receive switching control signal. Pin 2 is used as 5V standard working voltage output terminal. Its working principle is the same as the first voltage conversion circuit, ensuring the stability of BT2 voltage conversion and the controllability of power supply circuit.

[0045] like Figure 3 As shown, the reference voltage circuit provides a stable reference voltage, serving as a standard for voltage judgment by the comparator circuit. This circuit consists of resistors R5 and R6. One end of resistor R5 is connected to the 5V standard operating voltage, while the other end is connected to both the comparator circuit and resistor R6. The other end of resistor R6 is grounded. Through the precise voltage division effect of R5 and R6, a stable reference voltage adapted to the comparison requirements is formed, ensuring the accuracy of the judgment logic.

[0046] like Figure 4As shown, the comparator circuit, as the core judgment unit for power supply switching, is responsible for comparing the battery voltage signal transmitted by the sampling circuit with the reference voltage provided by the reference voltage circuit and outputting the corresponding switching control signal. Specifically, it consists of comparator U4, resistors R7, R8, and R9, and transistor Q3. Pin 3 of comparator U4 is connected to the connection point of resistors R1 and R2 (voltage divider point) of the first sampling circuit to receive the sampling voltage from the first battery power supply circuit; pin 2 is connected to the connection point of resistors R5 and R6 (voltage divider point) of the reference voltage circuit to access the reference voltage; pin 1 is connected to pin 1 (gate) of MOSFET Q1, one end of resistor R9, and one end of resistor R7; the other end of resistor R9 is connected to a 5V standard operating voltage, forming a pull-up circuit to ensure the stability of the control signal; the other end of resistor R7 is connected to pin 2 of transistor Q3, pin 1 of transistor Q3 is grounded, pin 3 is connected to one end of resistor R8 and pin 1 (gate) of MOSFET Q2, and the other end of resistor R8 is connected to a 5V standard operating voltage. Through the synergistic effect of the above components, the voltage signal comparison and control signal output are completed, and the reverse switching control of the two MOSFETs is realized.

[0047] In a preferred embodiment, the comparator circuit uses a single comparator U4 in conjunction with transistor Q3 to achieve interlock control:

[0048] When the BT1 voltage is normal, pin 1 (OUT) of U4 outputs a high level, which controls Q1 to conduct on one hand, and drives pin 2 (base) of transistor Q3 to obtain current and conduct on the other hand. The gate of Q2 is grounded through pin 3 (collector) and pin 1 (emitter) of Q3 and is cut off.

[0049] When the voltage of BT1 is insufficient, pin 1 (OUT) of U4 outputs a low level, causing Q1 to be cut off, Q3 to be cut off due to the lack of base current, and Q2 to be turned on by obtaining a high level through resistor R8.

[0050] This interlocking mechanism ensures that the two MOSFETs will not conduct simultaneously, thus avoiding conflicts between the two power supplies.

[0051] Example 2

[0052] This embodiment details the collaborative working mechanism of each module in the circuit. The selection and parameters of each component are as follows: Resistors R1 to R9 are all ordinary carbon film resistors with resistance values ​​of R1=10kΩ, R2=20kΩ, R3=10kΩ, R4=10kΩ, R5=15kΩ, R6=10kΩ, R7=10kΩ, R8=10kΩ, and R9=10kΩ, respectively; Capacitors C1 and C2 are ceramic capacitors with a capacitance of 100nF each; Capacitors C3 and C4 are aluminum electrolytic capacitors with a capacitance of 22μF each and a voltage rating of 10V; Chips U2 and U3 are TPS54302 DC-DC converters. The chip features high-efficiency voltage conversion capability, with a conversion efficiency of over 95%; comparator U4 uses an LM393 operational amplifier, offering a wide operating voltage range and rapid comparison response; MOSFETs Q1 and Q2 are Si2319CDS MOSFETs, characterized by low on-resistance and excellent switching characteristics; transistor Q3 is a 2N2219 NPN transistor, offering fast switching speed and low drive current; power supply BT1 is a 3.6V lithium thionyl chloride battery with a capacity ≥2000mAh, providing strong battery life; BT2 is a 6V power supply composed of four 1.5V alkaline dry batteries connected in series, offering low cost and easy replacement.

[0053] The overall circuit workflow is as follows:

[0054] After the system is powered on, the first battery power supply circuit provides priority power. The sampling circuit collects its voltage signal in real time and compares it with the reference voltage of the reference voltage circuit in the comparator circuit. The comparator outputs a control signal to drive the MOSFET of the power switching circuit to turn on and off. When the voltage of the first battery power supply circuit is lower than the set threshold, the comparator circuit outputs a reverse control signal to cut off the first power supply and turn on the second power supply, achieving seamless switching. The specific voltage parameters are calculated as follows:

[0055] Reference voltage calculation: Vref=VCC×R6 / (R5+R6)=5V×10kΩ / (15kΩ+10kΩ)=2.0V

[0056] First sampling voltage: Vs1=V_BT1×R2 / (R1+R2)=3.6V×20kΩ / (10kΩ+20kΩ)=2.4V;

[0057] During normal operation: 2.4V > 2.0V, the comparator outputs a high level;

[0058] Switching threshold: When the BT1 voltage drops to 3.0V, Vs1=3.0V×20kΩ / (10kΩ+20kΩ)=2.0V, which is equal to the reference voltage, triggering power supply switching.

[0059] The specific working process of the 3.6V lithium battery (BT1) power supply is as follows: After the system is powered on, BT1 of the first battery power supply circuit outputs a 3.6V voltage. This voltage is connected to pin 3 (VIN) of chip U2 in the first voltage conversion circuit. After being converted into a high-frequency pulse voltage by chip U2, it is output from pin 2 (SW). After being stored by inductor L1 and filtered by capacitor C3, a stable 5V voltage is obtained. At the same time, pin 3 (VIN) of chip U2 obtains the enable voltage by connecting to pin 5 (EN), realizing power-on self-start. The first sampling circuit uses resistors R1 and R2 to divide the output voltage of BT1, and capacitor C1 to filter out high-frequency interference, forming a stable sampling voltage signal (approximately 2.4V), which is then transmitted to pin 3 (IN+) of comparator U4. The reference voltage circuit uses resistors R5 and R6 to divide the voltage, forming a stable reference voltage of 2.0V, which is input to pin 2 (IN-) of comparator U4. Comparator U4 compares the sampled voltage of BT1 with the reference voltage and outputs a high-level control signal from pin 1 (OUT). The high-level signal is transmitted to pin 1 (gate) of MOSFET Q1, controlling Q1 to conduct and ensuring that the 5V voltage output by the first voltage conversion circuit is stably supplied to the gas meter through pin 2 of Q1. On the other hand, the high-level signal is transmitted to pin 2 (base) of transistor Q3 through resistor R7, turning Q3 on. Pin 1 (gate) of MOSFET Q2 remains in the off state because it is grounded through pin 3 (collector) and pin 1 (emitter) of Q3. The second battery power supply circuit enters standby mode and does not participate in the current power supply.

[0060] The specific process of switching and operating the 6V dry cell battery (BT2) power supply is as follows: When the voltage of BT1 in the first battery power supply circuit drops below the threshold (3.0V in this embodiment) due to discharge, the voltage signal collected by the first sampling circuit decreases synchronously (approximately 2.0V after voltage division). This voltage signal is transmitted to pin 3 (IN+) of comparator U4. Comparator U4 compares this voltage signal with the reference voltage (2.0V) and outputs a low-level control signal from pin 1 (OUT). This low-level signal causes MOSFET Q1 to turn off, and the 5V voltage output by the first voltage conversion circuit cannot be transmitted through Q1, so the first battery power supply circuit stops supplying power. At the same time, transistor Q3 is de-energized because pin 2 (base) is not powered. When the current is cut off, the power supply provides a high level to pin 1 (gate) of MOSFET Q2 through resistor R8, controlling Q2 to conduct; the BT2 of the second battery power supply circuit outputs a 6V voltage, which is connected to pin 3 (VIN) of chip U3 in the second voltage conversion circuit. After being converted into a high-frequency pulse voltage by chip U3, it is output from pin 2 (SW). After being stored by inductor L2 and filtered by capacitor C4, a stable 5V voltage is obtained. Pin 3 (VIN) of chip U3 obtains the enable voltage by connecting to pin 5 (EN) to achieve self-starting; this 5V voltage is connected to the gas meter power supply circuit through pin 2 (source) of MOSFET Q2 to realize automatic switching of power supply mode and ensure continuous and stable operation of gas meter.

[0061] This invention achieves seamless switching and stable adaptation between two power supply modes through precise selection and coordinated operation of hardware components. The circuit structure is simple, low-cost, and highly reliable, and can be widely used in the power supply systems of various civil and industrial gas meters.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0063] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A dual power supply circuit for a gas meter, characterized in that: It includes a battery power supply circuit, a voltage conversion circuit, a sampling circuit, a reference voltage circuit, a comparator circuit, and a power switching circuit; among which, The battery power circuit includes a first battery power circuit and a second battery power circuit, which provide main power supply and backup power supply respectively; The voltage conversion circuit includes a first voltage conversion circuit and a second voltage conversion circuit, which convert the battery voltage into the system operating voltage, respectively. The sampling circuit includes a first sampling circuit and a second sampling circuit, which perform voltage divider sampling on the two battery voltages respectively; The reference voltage circuit provides a stable reference voltage; The comparator circuit compares the sampled voltage with the reference voltage and outputs a switching control signal; The power switching circuit selects the effective power supply path based on the control signal.

2. The dual power supply circuit for a gas meter according to claim 1, characterized in that: The first battery power supply circuit includes power supply BT1, and the second battery power supply circuit includes power supply BT2; wherein, power supply BT1 is a 3.6V lithium battery, and power supply BT2 is a 6V dry cell battery. The positive terminal of power supply BT1 is connected to the voltage conversion circuit, and the negative terminal of power supply BT1 is grounded; the positive terminal of power supply BT2 is connected to the voltage conversion circuit, and the negative terminal of power supply BT2 is grounded.

3. A dual power supply circuit for a gas meter according to claim 2, characterized in that: The voltage conversion circuit includes a first voltage conversion circuit and a second voltage conversion circuit; the sampling circuit includes a first sampling circuit and a second sampling circuit; and the power switching circuit includes MOSFET Q1 and MOSFET Q2. The first voltage conversion circuit is connected to the power supply BT1 of the first sampling circuit and the first battery power supply circuit and MOSFET Q1, respectively. The second voltage conversion circuit is connected to the power supply BT2 of the second sampling circuit and the second battery power supply circuit, as well as the MOSFET Q2.

4. A dual power supply circuit for a gas meter according to claim 3, characterized in that: The first voltage conversion circuit includes chip U2, inductor L1 and capacitor C3; the first sampling circuit includes resistor R1, resistor R2 and capacitor C1. Pin 3 of chip U2 is connected to power supply BT1 and one end of resistor R1 respectively; pin 2 of chip U2 outputs a 5V standard operating voltage and is connected to one end of inductor L1, and the other end of inductor L1 is connected to capacitor C3 and pin 3 of MOSFET Q1 respectively; pin 3 of chip U2 is connected to pin 5 to realize power-on self-start. Pin 1 of MOSFET Q1 is connected to the comparator circuit; pin 2 of MOSFET Q1 serves as the 5V standard operating voltage output terminal. The other end of resistor R1 is connected to resistor R2, capacitor C1, and comparator circuit respectively; Pin 1 of chip U2, the other end of resistor R2 and capacitor C1 are all grounded.

5. A dual power supply circuit for a gas meter according to claim 4, characterized in that: The second voltage conversion circuit includes chip U3, inductor L2 and capacitor C4, and the second sampling circuit includes resistor R3, resistor R4 and capacitor C2. Pin 3 of chip U3 is connected to power supply BT2 and one end of resistor R3; pin 2 of chip U3 outputs a 5V standard operating voltage and is connected to one end of inductor L2, and the other end of inductor L2 is connected to capacitor C4 and pin 3 of MOSFET Q2; pin 3 of chip U3 is connected to pin 5 to achieve power-on self-starting. Pin 1 of MOSFET Q2 is connected to the comparator circuit; pin 2 of MOSFET Q2 serves as the 5V standard operating voltage output terminal. The other end of resistor R3 is connected to resistor R4 and capacitor C2 respectively; Pin 1 of chip U3, the other end of resistor R4 and capacitor C2 are all grounded.

6. A dual power supply circuit for a gas meter according to claim 5, characterized in that: The reference voltage circuit includes resistors R5 and R6; one end of resistor R5 is connected to the 5V standard operating voltage, and the other end of resistor R5 is connected to the comparator circuit and resistor R6 respectively; the other end of resistor R6 is grounded.

7. A dual power supply circuit for a gas meter according to claim 6, characterized in that: The comparator circuit includes comparator U4, resistors R7, R8, and R9, and transistor Q3; pin 3 of comparator U4 is connected to the first voltage conversion circuit; pin 2 of comparator U4 is connected to the reference voltage circuit; pin 1 of comparator U4 is connected to pin 1 of MOSFET Q1, one end of resistor R9, and one end of resistor R7. The other end of resistor R9 is connected to the 5V standard operating voltage, and the other end of resistor R7 is connected to pin 2 of transistor Q3; pin 1 of transistor Q3 is grounded; pin 3 of transistor Q3 is connected to one end of resistor R8 and pin 1 of MOSFET Q2. The other end of resistor R8 is connected to the 5V standard operating voltage.

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