Power supply circuit for micro differential pressure transmitter and transmitter

Abstract

The utility model provides a power supply circuit for a micro differential pressure transmitter and the transmitter. The power supply circuit comprises a power supply management module, a first power supply module and a second power supply module which are connected in sequence. The power management module is connected with an external power supply, and the power management module is used for outputting a first power supply with stable first voltage and first current. The first power supply module is used for outputting a second power supply to supply power to the display module of the transmitter. The third power supply circuit is connected to the common end of the first power module and the second power module. And the third power supply circuit supplies power to the micro differential pressure core body and the transmitting circuit of the transmitter, and the current value of the third power supply circuit is obtained by subtracting the working current of the second power supply module from the first current. According to the utility model, through accurate current control and distribution, stable current supply of the transmitter in different working states is ensured, and the problem of current fluctuation caused by working state switching of the digital micro-differential pressure core body in the existing micro-differential pressure transmitter is improved.

Description

Technical Field

[0001] This utility model relates to the field of transmitter technology, and in particular to a power supply circuit and transmitter for a differential pressure transmitter. Background Technology

[0002] In the field of industrial automation, differential pressure transmitters are widely used for pressure measurement of gases or liquids, and their core component is the differential pressure sensor chip. Currently, most differential pressure transmitters on the market use digital differential pressure chips for data acquisition and convert the acquired data into a standard 4–20mA current signal output through signal conversion circuits. However, existing technologies have the following problems in practical applications:

[0003] Significant differences in current consumption: Different manufacturers' differential pressure cores have inconsistent current consumption during operation. Some cores have higher power consumption, which may cause the transmitter's current supply to be unstable when the current output is low (such as 4mA).

[0004] Instantaneous current fluctuation problem: The current of the digital differential pressure transmitter core is small when in sleep mode, but it can suddenly rise (typically reaching 1-2mA) during operation (such as data acquisition or communication). This transient current change can easily cause large fluctuations or ripples in the output current for 4-20mA transmitters, especially when the transmitter's output current is close to the low power consumption state of 4mA, affecting the stability and accuracy of signal transmission.

[0005] Limitations of traditional filtering solutions: Existing technologies typically use large-capacity capacitors to suppress current fluctuations, but this method has limited effectiveness, especially under conditions of high chip power consumption or drastic current transients, where output current instability may still occur. Furthermore, large-capacity capacitors increase circuit size and cost, hindering miniaturization and low-power design.

[0006] Therefore, there is an urgent need for a current stabilization solution that can adapt to micro differential voltage cores with different power consumption. Utility Model Content

[0007] To address the aforementioned issues, the present invention aims to provide a power supply circuit and transmitter for a differential pressure transmitter. By precisely controlling and distributing the current, it ensures a stable current supply to the transmitter under different operating conditions, avoiding current fluctuations caused by switching of the core's operating state. This improves the current fluctuation problem caused by switching of the digital differential pressure core's operating state in existing differential pressure transmitters.

[0008] This utility model is achieved through the following technical solution:

[0009] A low-power power supply circuit for a differential pressure transmitter includes:

[0010] A power management module is connected to an external power supply and is used to output a first power supply with a stable first voltage and a first current.

[0011] A first power module is connected to the output terminal of the power management module. The first power module is used to output a second power supply, which powers the display module of the transmitter.

[0012] The second power supply module is connected in series with the first power supply module, and the third power supply circuit is connected to the common terminal of the first power supply module and the second power supply module; the third power supply circuit supplies power to the differential pressure core and the transmitter circuit of the transmitter, and the current value of the third power supply circuit is the first current minus the operating current of the second power supply module.

[0013] Furthermore, the power management module includes a voltage regulator chip and a sixth resistor connected in series at the output terminal of the voltage regulator chip. The input terminal of the voltage regulator chip is connected to the external power supply, and the other end of the sixth resistor is connected to the first power module.

[0014] Furthermore, the first power module includes a first reference voltage chip, a fifteenth resistor connected in parallel between the cathode and the reference electrode of the first reference voltage chip, and an eighth resistor connected in parallel between the anode and the reference electrode of the first reference voltage chip; the cathode of the first reference voltage chip is connected to the power management module, and the anode of the first reference voltage chip is connected to the second power module.

[0015] Furthermore, the ratio of the fifteenth resistor to the eighth resistor is 1:5.

[0016] Furthermore, the first reference voltage chip is an AZ431.

[0017] Furthermore, the second power module includes a second reference voltage chip, a fifth resistor connected in parallel between the cathode and the reference electrode of the second reference voltage chip, and a seventh resistor connected in parallel between the anode and the reference electrode of the second reference voltage chip; the cathode of the second reference voltage chip is connected to the first power module, and the anode of the second reference voltage chip is grounded.

[0018] Furthermore, the second reference voltage chip is an AZ432, and the ratio of the fifth resistor to the seventh resistor is 17:12.

[0019] Furthermore, the voltage regulator chip used is the SG2375.

[0020] Furthermore, the third power supply circuit includes a filter capacitor or a filter capacitor group, one end of which is connected to the common terminal of the first power module and the second power module, and the other end is grounded. The end of the filter capacitor or filter capacitor group away from ground is the output terminal of the third power supply circuit.

[0021] Furthermore, a transmitter includes the aforementioned power supply circuit for a differential pressure transmitter, and further includes a power protection circuit, a control circuit, a current transmission circuit, and a signal acquisition circuit. The power protection circuit, the power supply circuit, the current transmission circuit, and the signal acquisition circuit are all connected to the control circuit, and the control circuit, the current transmission circuit, and the power protection circuit are all connected to the power supply circuit. The power protection circuit is also connected to the current transmission circuit.

[0022] Compared with the prior art, the technical solution of this utility model and its beneficial effects are as follows:

[0023] (1) The power supply circuit of this utility model outputs a stable first voltage and a first current through the power management module, ensuring a stable current supply for the entire power supply circuit, thereby improving the current supply stability of the differential pressure transmitter. Through the series design of the first power module and the second power module, the current value of the differential pressure core (third power supply) is always the first current minus the fixed operating current of the second power module, realizing precise current distribution, ensuring a stable current supply for the differential pressure core and the transmitter circuit, avoiding the impact of current fluctuations on the stability and accuracy of signal transmission, thereby eliminating the influence of power consumption differences of cores from different manufacturers on the total current, and ensuring the stability of the 4mA low current output.

[0024] (2) The power supply circuit of this utility model has a constant current and does not require an additional large-capacity capacitor to suppress current fluctuations, thereby simplifying the circuit design, reducing cost and size, and facilitating the miniaturization and low-power design of the equipment. Attached Figure Description

[0025] Figure 1 This is a circuit diagram of a power supply circuit for a differential pressure transmitter provided in an embodiment of this utility model;

[0026] Figure 2 This is a block diagram of a transmitter provided in an embodiment of the present invention.

[0027] Illustration:

[0028] Power management module-100; first power module-200; second power module-300; third power supply circuit-400. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0030] See Figure 1 A power supply circuit for a differential pressure transmitter includes a power management module 100, a first power supply module 200, and a second power supply module 300.

[0031] The power management module 100 is connected to an external 24V power supply and outputs a first power supply with a stable first voltage and first current. The first power module 200 is connected to the output terminal of the power management module 100 and outputs a second power supply, which powers the transmitter's display module. The second power module 300 is connected in series with the first power module 200. A third power supply circuit 400 is connected to the common terminal of the first power module 200 and the second power module 300. The third power supply circuit 400 powers the transmitter's differential pressure core and transmitting circuit, and the current value of the third power supply circuit is the first current minus the operating current of the second power module.

[0032] The power management module 100 outputs a stable first current. Since the first power module 200 and the second power module 300 are connected in series, the current at the common terminal between them is also the first current. Furthermore, since the third power supply circuit 400 is connected in parallel with the second power module 300, and the second power module 300's operating current is constant, the current in the third power supply circuit 400 is obtained by subtracting the constant operating current of the second power module from the stable first current, resulting in a stable current value. Therefore, the current value supplied to the transmitter's differential pressure core and the third power supply circuit of the transmitter circuit is constant and unaffected by the switching of the differential pressure core's operating state. The circuit in this embodiment, through precise current control and distribution, ensures a stable current supply to the transmitter under different operating states, avoiding current fluctuations caused by core operating state switching, thereby improving the current fluctuation problem caused by the switching of the digital differential pressure core's operating state in existing differential pressure transmitters. Meanwhile, since the first power module 200 and the second power module 300 are connected in series, this power supply circuit can supply power to the display module without affecting the current of the circuit.

[0033] The power management module 100 includes a voltage regulator chip U3 and a resistor R6 connected in series at the output terminal of the voltage regulator chip U3. The input terminal of the voltage regulator chip U3 is connected to an external 24V power supply, and the other end of the resistor R6 is connected to the first power module 200. In this embodiment, the voltage regulator chip U3 uses an SG2375 LDO to regulate the input 24V voltage to 3.3V before outputting it, providing a stable power supply for the entire circuit. Simultaneously, the current of the entire circuit is controlled at 3.66mA by setting the resistor R6.

[0034] The first power supply module 200 includes a first reference voltage chip Q4, a resistor R15 connected in parallel between the cathode and reference electrode of the first reference voltage chip Q4, and a resistor R8 connected in parallel between the anode and reference electrode of the first reference voltage chip Q4. The cathode of the first reference voltage chip Q4 is connected to the power management module 100, specifically to the other end of the resistor R6, and the anode of the first reference voltage chip Q4 is connected to the second power supply module 300. The ratio of resistor R15 to resistor R8 is 1:5. The first reference voltage chip Q4 is an AZ431, which has low dynamic impedance characteristics, suppresses power supply noise, and reduces coupling interference from the display module to the power supply circuit of the differential voltage core. The voltage between the anode and reference electrode of the AZ431 reference chip is constant at 2.5V. 2.5*(1 / 5)+2.5=3V, that is, a 3V voltage is generated by the AZ431 reference chip in conjunction with resistors R15 and R8 to power the display module.

[0035] The second power supply module 300 includes a second reference voltage chip Q1, a resistor R5 connected in parallel between the cathode and reference electrode of the second reference voltage chip Q1, and a resistor R7 connected in parallel between the anode and reference electrode of the second reference voltage chip Q1. The cathode of the second reference voltage chip Q1 is connected to the anode of the first reference voltage chip Q4, and the anode of the second reference voltage chip Q1 is grounded. By dividing the voltage through resistors R7 and R5, the operating current of the second power supply module is fixed, ensuring that the current value of the third power supply circuit is strictly equal to the first current minus this fixed value, thereby eliminating the influence of instantaneous current fluctuations in the chip on the total output.

[0036] In this embodiment, the second reference voltage chip Q1 is an AZ432, whose low quiescent current and high efficiency characteristics are suitable for industrial automation scenarios, reducing the power management module's own power consumption from occupying the 4-20mA circuit and improving overall energy efficiency. The ratio of resistor R5 to resistor R7 is 17:12. The voltage between the anode and reference terminal of the AZ432 reference chip is constant at 1.25V. 1.25*(17 / 12)+1.25=3V, that is, using the AZ432 reference voltage chip in conjunction with resistors R5 and R7, another 3V reference voltage VCC is generated to power the digital differential pressure core and transmitter circuit. The stable operating current of the AZ432 reference voltage chip is 0.1mA, so approximately 3.56mA of stable current can power the digital differential pressure core and transmitter circuit, achieving low-power power supply.

[0037] The third power supply circuit 400 includes a filter capacitor or a filter capacitor group. One end of the filter capacitor or filter capacitor group is connected to the common terminal of the first power supply module and the second power supply module, and the other end is grounded to GND. The end of the filter capacitor or filter capacitor group away from ground is the output terminal VCC of the third power supply circuit.

[0038] Since the current of the entire circuit is constant, there is no need to add a large-capacity capacitor to suppress current fluctuations, which simplifies the circuit design, reduces cost and size, facilitates the miniaturization and low-power design of the device, and can adapt to micro differential pressure cores with different power consumption, as well as the switching of the working mode of the micro differential pressure core, thus improving the system's compatibility and reliability.

[0039] See Figure 2 This embodiment also provides a transmitter, including the aforementioned low-power power supply circuit for a differential pressure transmitter, and further including a power protection circuit, a control circuit, a current transmission circuit, and a signal acquisition circuit. The power protection circuit, power supply circuit, current transmission circuit, and signal acquisition circuit are all connected to the control circuit, and the control circuit, current transmission circuit, and power protection circuit are all connected to the power supply circuit; the power protection circuit is also connected to the current transmission circuit. For details on the control circuit, power protection circuit, current transmission circuit, etc., please refer to Chinese Utility Model Patent Publication No. CN220871960U, which will not be described in detail here.

[0040] The foregoing description illustrates and describes preferred embodiments of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the present invention through the foregoing teachings or related technical or knowledge. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A power supply circuit for a differential pressure transmitter, characterized in that, include: A power management module is connected to an external power supply and is used to output a first power supply with a stable first voltage and a first current. A first power module is connected to the output terminal of the power management module. The first power module is used to output a second power supply, which powers the display module of the transmitter. The second power supply module is connected in series with the first power supply module, and the third power supply circuit is connected to the common terminal of the first power supply module and the second power supply module; the third power supply circuit supplies power to the differential pressure core and the transmitter circuit of the transmitter, and the current value of the third power supply circuit is the first current minus the operating current of the second power supply module.

2. The power supply circuit for a differential pressure transmitter according to claim 1, characterized in that, The power management module includes a voltage regulator chip and a sixth resistor connected in series at the output terminal of the voltage regulator chip. The input terminal of the voltage regulator chip is connected to the external power supply, and the other end of the sixth resistor is connected to the first power module.

3. The power supply circuit for a differential pressure transmitter according to claim 1, characterized in that, The first power module includes a first reference voltage chip, a fifteenth resistor connected in parallel between the cathode and the reference electrode of the first reference voltage chip, and an eighth resistor connected in parallel between the anode and the reference electrode of the first reference voltage chip; the cathode of the first reference voltage chip is connected to the power management module, and the anode of the first reference voltage chip is connected to the second power module.

4. The power supply circuit for a differential pressure transmitter according to claim 3, characterized in that, The ratio of the fifteenth resistor to the eighth resistor is 1:

5.

5. The power supply circuit for a differential pressure transmitter according to claim 3, characterized in that, The first reference voltage chip is AZ431.

6. The power supply circuit for a differential pressure transmitter according to claim 1, characterized in that, The second power module includes a second reference voltage chip, a fifth resistor connected in parallel between the cathode and the reference electrode of the second reference voltage chip, and a seventh resistor connected in parallel between the anode and the reference electrode of the second reference voltage chip; The cathode of the second reference voltage chip is connected to the first power module, and the anode of the second reference voltage chip is grounded.

7. The power supply circuit for a differential pressure transmitter according to claim 6, characterized in that, The second reference voltage chip is an AZ432, and the ratio of the fifth resistor to the seventh resistor is 17:

12.

8. The power supply circuit for a differential pressure transmitter according to claim 2, characterized in that, The voltage regulator chip used is SG2375.

9. The power supply circuit for a differential pressure transmitter according to claim 1, characterized in that, The third power supply circuit includes a filter capacitor or a filter capacitor group. One end of the filter capacitor or filter capacitor group is connected to the common terminal of the first power module and the second power module, and the other end is grounded. The end of the filter capacitor or filter capacitor group away from the ground is the output terminal of the third power supply circuit.

10. A transmitter, characterized in that, The device includes a power supply circuit for a differential pressure transmitter as described in any one of claims 1 to 9, and further includes a power protection circuit, a control circuit, a current transmission circuit, and a signal acquisition circuit. The power protection circuit, the power supply circuit, the current transmission circuit, and the signal acquisition circuit are all connected to the control circuit. The control circuit, the current transmission circuit, and the power protection circuit are all connected to the power supply circuit. The power protection circuit is also connected to the current transmission circuit.

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