CN219304700U - Power supply circuit and flowmeter - Google Patents

Abstract

The application provides a power supply circuit and flowmeter, this power supply circuit includes: the power supply module, the LDO module, the forward DCDC module and the power supply control module; the LDO module and the forward DCDC module are respectively connected with the power supply module and the power supply control module; the LDO module is used for outputting forward working voltage; the positive DCDC module is used for outputting negative working voltage; the power supply control module is used for controlling the LDO module to provide positive working voltage for the first load and controlling the positive DCDC module to provide negative working voltage for the second load. The power supply circuit and the flowmeter provided by the application have the advantages that the LDO module and the forward DCDC module are adopted in the power supply circuit, the current in the power supply circuit can be reduced, the power supply circuit is protected, the power consumption of equipment powered by the power supply circuit is reduced, and the service life of the equipment is prolonged.

Description

Power supply circuit and flowmeter

Technical Field

The application relates to the technical field of flowmeters, in particular to a power supply circuit and a flowmeter.

Background

The flowmeter has the advantages of high measuring range ratio, high precision, good stability and the like, and is widely applied to metering engineering. Taking an electromagnetic water meter as an example, each load module in the electromagnetic water meter needs positive voltage and negative voltage or different voltages to supply power, however, the internal space of the electromagnetic water meter is limited, and the number of batteries cannot be increased infinitely, so that the number of batteries can be reduced by adopting a voltage conversion circuit, and meanwhile, the battery voltage is converted into positive voltage or negative voltage to supply power for the load. The inside power supply circuit that is provided with for load module power supply of electromagnetism water gauge, this power supply circuit includes: a battery and a voltage conversion module. The battery conversion module is used for converting the voltage provided by the battery into different working voltages so as to realize the electricity utilization requirements of different load modules. Currently, a voltage conversion module of an electromagnetic water meter mainly includes a Direct Current-Direct Current (DCDC) converter for outputting a positive working voltage, and a charge pump converter for outputting a negative working voltage.

However, the DCDC converter and the charge pump converter can cause current multiplication in the voltage conversion process, and the quiescent current of the power supply circuit is larger, so that the power consumption of the power supply circuit is larger, and the service life of the electromagnetic water meter is reduced.

Disclosure of Invention

The application provides a power supply circuit and flowmeter for solve power supply circuit and lead to the great problem of consumption because of quiescent current.

In a first aspect, the present application provides a power supply circuit comprising: the power supply module, the LDO module, the forward DCDC module and the power supply control module; the LDO module and the forward DCDC module are respectively connected with the power supply module and the power supply control module;

the power supply control module is used for controlling the LDO module to provide positive working voltage for the first load and controlling the positive DCDC module to provide negative working voltage for the second load.

In an embodiment of the present application, the LDO module includes: an LDO chip and a first switch submodule;

the first end of the power supply module is connected with the input end of the LDO chip, the output end of the LDO chip is connected with the first end of the first switch sub-module, the second end of the first switch sub-module is connected with the first output end of the power supply control module, the grounding end of the LDO chip is grounded, and the third end of the first switch sub-module is connected with the first load;

the LDO chip is used for converting the output voltage of the power supply module into forward working voltage;

the power supply control module is used for controlling the first switch submodule to switch on or off a power supply path between the LDO chip and the first load.

In an embodiment of the present application, the LDO module further includes: a first slow start sub-module for delaying power-up time; the first slow start submodule comprises: a first capacitor and a first resistor;

the first end of the first capacitor is connected with the first end of the first switch sub-module, the second end of the first capacitor is connected with the first end of the first resistor and the second end of the first switch sub-module respectively, and the second end of the first resistor is connected with the first output end of the power supply control module.

In an embodiment of the present application, the LDO module further includes: a first filtering sub-module and/or a second filtering sub-module;

the first end of the first filtering sub-module is connected with the input end of the LDO chip, and the second end of the first filtering sub-module is grounded;

the first end of the second filtering sub-module is connected with the output end of the LDO chip, and the second end of the second filtering sub-module is grounded.

In an embodiment of the present application, according to any one of the preceding claims, the forward DCDC module includes: the direct current DC (direct current) chip, an inductor, a second switch submodule and a rectifier submodule;

the first end of the power supply module is connected with the input end of the forward DCDC chip, the first output end of the forward DCDC chip is connected with the first end of the inductor, the second end of the inductor is connected with the second output end of the forward DCDC chip, the second output end of the forward DCDC chip is respectively connected with the first end of the rectifier sub-module and the first end of the second switch sub-module, the second end of the second switch sub-module is connected with the second load, the third end of the second switch sub-module is connected with the second output end of the power supply control module, the fourth end of the second switch sub-module is connected with the power supply module, and the second end of the inductor and the second end of the rectifier sub-module are grounded;

the enabling end of the forward DCDC chip is connected with the third output end of the power supply control module, the mode switching end of the forward DCDC chip is connected with the fourth output end of the power supply control module, and the grounding end of the forward DCDC chip is grounded;

the positive DCDC chip is used for converting the output voltage of the power supply module into negative working voltage through the inductor and the rectifying sub-module;

and the power supply control module is used for controlling the second switch submodule to switch on or off a passage between the forward DCDC chip and the second load.

In an embodiment of the present application, the second switch submodule includes: a first switch, a second switch, and a second resistor;

the first end of the first switch is the first end of the second switch sub-module, the second end of the first switch is connected with the first end of the second switch, and the third end of the first switch is the second end of the second switch sub-module;

the second end of the second switch is a third end of the second switch sub-module, and the third end of the second switch is a fourth end of the second switch sub-module; the first end of the second resistor is connected with the first end of the first switch, and the second end of the second resistor is connected with the second end of the first switch.

In an embodiment of the present application, the forward DCDC module further includes: the second is slowly opened submodule piece, the second is slowly opened submodule piece and is included: a second capacitor and a third resistor;

the first end of the second capacitor and the first end of the third resistor are connected with the first end of the first switch, and the second end of the second capacitor and the second end of the third resistor are connected with the third end of the first switch.

In an embodiment of the present application, the forward DCDC module further includes: a fourth resistor and a fifth resistor;

the first end of the fourth resistor is connected with the second output end of the forward DCDC chip, the second end of the fourth resistor is connected with the first end of the fifth resistor, and the second end of the fifth resistor is connected with the first end of the second switch submodule.

In an embodiment of the present application, the forward DCDC module further includes: a third filtering sub-module;

the first end of the third filtering sub-module is connected with the input end of the forward DCDC module, and the second end of the third filtering sub-module is grounded.

In a second aspect, the present application provides a flow meter comprising a first load, a second load, and a power supply circuit provided in any one of the first aspects;

the power supply circuit is used for providing positive working voltage for the first load and providing negative working voltage for the second load.

The power supply circuit and the flowmeter mainly comprise a power supply module, an LDO module, a forward DCDC module and a power supply control module. The power supply module outputs positive voltage by adopting the LDO module, and outputs negative voltage to the DCDC module, so that the quiescent current of the circuit is reduced, and the power consumption of the power supply circuit is reduced.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.

Fig. 1 is a schematic diagram of a power supply circuit according to the prior art;

fig. 2 is a schematic structural diagram of a power supply circuit according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of an LDO module according to an embodiment of the present application;

fig. 4 is a schematic structural diagram of a forward DCDC module according to an embodiment of the present application.

Specific embodiments thereof have been shown by way of example in the drawings and will herein be described in more detail. These drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments.

Detailed Description

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples are not representative of all implementations consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the accompanying claims.

Fig. 1 is a schematic structural diagram of an electromagnetic water meter according to the prior art. As shown in fig. 1, the electromagnetic water meter includes: a power supply circuit and a plurality of load modules requiring power supply. Fig. 1 is a schematic diagram of two load modules, namely a load module 1 and a load module 2. The operating voltage of the load module 1 is assumed to be a positive operating voltage and the operating voltage of the load module 2 is assumed to be a negative operating voltage.

The power supply circuit includes: a battery, and a voltage conversion module. The voltage conversion module includes a DCDC converter, and a charge pump converter. The battery is connected with the DCDC converter and the charge pump converter respectively. The DCDC converter is connected with the load module 1 to provide positive working voltage for the load module 1, and the charge pump converter is connected with the load module 2 to provide negative working voltage for the load module 2.

However, when the power supply is realized in the above manner, the static current of the DCDC converter and the charge pump converter is larger, which results in large power consumption of the voltage conversion module, and further, large power consumption of the power supply circuit, thereby reducing the service life of the electromagnetic water meter.

In view of this, the present application provides a power supply circuit, through adopting the LDO module to provide positive operating voltage to and through adopting positive DCDC module to provide negative operating voltage, can solve power supply circuit and lead to the great problem of consumption because of quiescent current.

It should be understood that the power supply circuit provided in the present application may be applicable to any device in which a load module requiring a positive operating voltage is built-in, and a load module requiring a negative operating voltage is built-in. Such as the aforementioned electromagnetic water meter, or other types of flow meters, etc.

The following describes the technical solutions of the present application and how the technical solutions of the present application solve the above technical problems in detail with specific embodiments. The following exemplary embodiments may be combined with each other and may not be described in detail in some embodiments for the same or similar concepts or processes. Embodiments of the present application will be described below with reference to the accompanying drawings.

Fig. 2 is a schematic structural diagram of a power supply circuit according to an embodiment of the present application. As shown in fig. 2, the power supply circuit may include: the power supply module, the LDO module, the forward DCDC module and the power supply control module; the LDO module and the forward DCDC module are respectively connected with the power supply module and the power supply control module.

The power supply module is used for outputting a fixed direct-current voltage. The power supply module may comprise at least one battery, for example a lithium battery or other type of battery, etc., connected in series, as examples. Or the power supply module is used for an external power supply to convert the voltage provided by the external power supply into the fixed direct-current voltage. The external power source can be an alternating current power source or a direct current power source.

And the LDO module is used for converting the output voltage of the power supply module into forward working voltage to supply power for the first load needing forward voltage. The first load may be, for example, an electric module using a forward operating voltage in a device using the power supply circuit. Taking a flowmeter as an example, the first load may be, for example, a control module, a signal processing module, or the like. The number and type of the first loads are not limited in this application.

And the positive DCDC module is used for supplying power to a second load requiring negative voltage by converting the output voltage of the power supply module into the negative working voltage. The second load may be, for example, a power module using a negative operating voltage in a device using the power supply circuit. It should be understood that, as used herein, a power module using a negative operating voltage refers to a power module whose communication interface needs to be connected to a negative voltage. The number and type of the second loads are not limited in this application.

And the power supply control module is used for controlling the LDO module to provide positive working voltage for the first load and controlling the positive DCDC module to provide negative working voltage for the second load. For example, the power control module may control whether the LDO module provides the forward operating voltage for the first load by turning on or off a path between the LDO module and the first load. The power supply control module may control whether the forward DCDC module provides the forward operating voltage to the first load by turning on or off a path between the forward DCDC module and the second load.

The power supply control module may control whether the LDO module provides a positive operating voltage to the first load and controls whether the positive DCDC module provides a negative operating voltage to the second load, for example, according to whether a device using the power supply circuit is operating. In addition, in the power supply process, the power supply control module can also control the positive DCDC module to provide negative working voltage for the second load by controlling the LDO module to provide positive working voltage for the first load, so that the effect of periodically supplying power to the load needing periodic power supply is achieved.

According to the power supply circuit, the power supply module realizes the conversion of positive and negative voltages through the LDO module and the forward DCDC module and supplies power to a load. The LDO module and the forward DCDC module have low quiescent current when working, and the power consumption of a power supply circuit is reduced.

One possible configuration of the LDO module and the forward DCDC module is described in detail below.

Fig. 3 is a schematic structural diagram of an LDO module according to an embodiment of the present application, and as shown in fig. 3, the LDO module may include an LDO chip U15 and a first switch sub-module.

In some embodiments, main-PWR is connected to input Vin of LDO chip U15. Main-PWR may be referred to as a first end of the power module, or as a point of connection to the first end of the power module. The following examples are each illustrated with respect to a first end of a Main-PWR that may be referred to as a power module.

The output terminal Vout of the LDO chip U15 is connected to the first terminal a of the first switching sub-module, the second terminal B of the first switching sub-module is connected to the first output terminal pwr_op_ctl of the power supply control module, the ground terminal DGND of the LDO chip U15 is grounded, and the third terminal C of the first switching sub-module is the output terminal of the LDO module, i.e. the VCC terminal shown in fig. 3, which is used to connect to the first load to provide a fixed forward voltage, e.g. a forward voltage of 2.5V.

The LDO chip U15 is used for converting the output voltage of the power supply module into a forward working voltage. The forward operating voltage may be a fixed value. Because the voltage conversion tube in the LDO chip U15 adopts a P-channel metal oxide semiconductor field effect transistor (Metal Oxide Semiconductor Field Effect Transistor, MOSFET), the P-channel MOSFET is driven by voltage without larger current, thereby reducing the quiescent current when converting the forward working voltage.

When the ultra-low power consumption LDO chip is adopted, the quiescent current can be further effectively reduced. In addition, the output ripple wave of the LDO chip is smaller, the noise is smaller, and the requirement of high-precision power supply can be met.

And the power supply control module is used for controlling the first switch submodule to switch on or off a power supply path between the LDO chip and the first load. The power control module is not output in fig. 3, and only the first output terminal pwr_op_ctl of the power control module for connection with the second terminal B of the switch sub-module is shown.

For example, the power control module may control the first switch sub-module to be turned on or off by a high-low level. Specifically, whether the high level is turned on or the low level is turned on depends on the control mode of the first switch submodule itself. Taking the example that the first switch submodule is turned on when receiving the high level and turned off when receiving the low level, when the first output end PWR_OP_CTL of the power supply control module outputs the high level, the first switch submodule turns on a power supply path between the LDO chip and the first load to supply power for the first load; when the first output terminal pwr_op_ctl of the power supply control module outputs a low level, the first switch sub-module turns off the power supply circuit between the LDO module and the first load.

The first switch submodule can be turned on or turned off by a control signal, for example, a triode, a MOS transistor, a thyristor, and the like.

Taking an MOS transistor as an example, as shown in fig. 3, a source S of the MOS transistor Q6 is connected to the LDO chip U15, a gate G is connected to the power supply control module, one end (i.e., VCC end) of a drain D is connected to the first load, and the other end is grounded. For example, the terminal may be grounded through a capacitor C89. The capacitor C89 is used for filtering the output voltage of the LDO module.

When the first output end PWR_OP_CTL of the power supply control module is at a high level, the MOS transistor Q6 is closed; when the power supply control module first output terminal pwr_op_ctl output is at a low level, the MOS transistor Q6 is turned on.

In some embodiments, the LDO module may further include a first slow start sub-module.

Illustratively, the first slow start submodule includes a first capacitor C87 and a first resistor R54. The first end of the first capacitor C87 is connected to the first end a of the first switch sub-module (for example, the MOS transistor in fig. 3 is the source S of the MOS transistor Q6), and the second end of the first capacitor C87 is connected to the first end of the first resistor R54 and the second end B of the first switch sub-module (for example, the MOS transistor in fig. 3 is the gate G of the MOS transistor Q6), respectively, and the second end of the first resistor R54 is connected to the first output pwr_op_ctl of the power supply control module.

That is, the first capacitor C87 is connected in parallel between the first terminal a and the second terminal B of the first switch sub-module (for example, between the source S and the gate G of the MOS transistor Q6 in fig. 3), that is, the voltage across the first capacitor C87 is equal to the voltage across the first terminal a and the second terminal B of the first switch sub-module (for example, the voltage across the source S and the gate G of the MOS transistor Q6). When the first capacitor C87 is not charged, the first switch submodule is not conducted; when the first capacitor C87 is fully charged, the first switch submodule is turned on, and the charging time of the first capacitor C87 can delay the opening (i.e., closing) of the first switch submodule.

Because the first load using the forward working voltage is usually a capacitive load, when the first switch submodule is turned on for a moment, a very large instant pulse circuit exists, and the transient current can be greatly reduced by designing the first slow screwdriver module in the circuit, so that the damage of the instantaneous high current to all devices in the circuit can be avoided, the protection of the circuit is realized, and the service life of all devices is prolonged.

With continued reference to fig. 3, in an embodiment of the present application, a first filtering sub-module may be further connected between the power supply module and the LDO chip U15, so as to reduce ripple interference when the current output by the power supply module is input into the LDO chip U15. The first end of the first filtering sub-module is connected with the input end Vin of the LDO chip, and the second end of the first filtering sub-module is grounded. Or, the first end of the first filtering sub-module is connected with the first end Main-PWR of the power supply module, and the second end of the first filtering sub-module is grounded. Or, the first end of the first filtering sub-module is connected at any point between the first end Main-PWR of the power supply module and the input end Vin of the LDO chip, and the second end of the first filtering sub-module is grounded.

For example, the first filtering sub-module may include a capacitor C79 and a capacitor C85, where the capacitor C79 and the capacitor C85 are connected in parallel, one end of the capacitor C79 and one end of the capacitor C85 are connected between the power supply module and the LDO chip U15, and the other end of the capacitor C79 and the other end of the capacitor C85 are grounded. For example, the capacitor C79 is a large capacitor, the capacitor C85 is a small capacitor, or the capacitor C79 is a small capacitor, and the capacitor C85 is a large capacitor, so as to filter high-frequency and low-frequency interference through the two capacitors.

It should be appreciated that the above-mentioned large and small capacitances can be relative concepts, i.e. the capacitance of one of the two capacitances is large relative to the capacitance of the other capacitance, or the above-mentioned large and small capacitances are related to the output voltage of the power supply module, so as to achieve filtering of high and low frequency disturbances.

In addition, the type and number of capacitors specifically included in the first filtering submodule are not limited in the application. For example, the first filtering sub-module may include at least one large capacitance, without a small capacitance. Alternatively, the first filtering sub-module may include at least one small capacitance, no large capacitance, or the first filtering sub-module may include at least one large capacitance, and at least one small capacitance, etc. Fig. 3 is a schematic diagram illustrating an example in which the first filtering submodule includes a large capacitor and a small capacitor.

In an embodiment of the present application, a second filtering sub-module may be further connected between the LDO chip U15 and the first switching sub-module, so as to reduce ripple interference when the current of the LDO chip U15 is input into the first switching sub-module. The first end of the second filtering sub-module is connected with the output end Vout of the LDO chip, and the second end of the second filtering sub-module is grounded. Or, the first end of the second filtering sub-module is connected with the first end A of the first switch sub-module, and the second end of the second filtering sub-module is grounded. Alternatively, the first end of the second filter sub-module is connected to any point between the output terminal Vout of the LDO chip and the first end a of the first switch sub-module, and the second end of the second filter sub-module is grounded.

For example, the second filtering sub-module may include a capacitor C81, a capacitor C82, and a capacitor C93, where the capacitor C81, the capacitor C82, and the capacitor C93 are connected in parallel, one end of the capacitor C81, the capacitor C82, and the capacitor C93 is connected between the LDO chip U15 and the first switching sub-module, and the other end of the capacitor C81, the capacitor C82, and the capacitor C93 is grounded. For example, the capacitor C81 is a large capacitor, the capacitor C85 and the capacitor C93 are small capacitors, or the capacitor C81 and the capacitor C85 are large capacitors, the capacitor C93 is a small capacitor, or the capacitor C81 is a small capacitor, the capacitor C85 is a large capacitor, the capacitor C93 is a small capacitor, or the like, so as to filter out the interference of the high frequency and the low frequency through the three capacitors with different sizes.

The type and number of capacitances specifically included in the second filtering submodule are also not limited in the present application. For example, the second filtering sub-module may include at least one large capacitance, without a small capacitance. Alternatively, the second filtering sub-module may include at least one small capacitance, no large capacitance, or the second filtering sub-module may include at least one large capacitance, and at least one small capacitance, etc. Fig. 3 is a schematic diagram illustrating an example in which the second filtering submodule includes 3 capacitors.

The first filtering sub-module and the second filtering sub-module can be set according to actual requirements. For example, the LDO module may include only the first filtering sub-module, may include only the second filtering sub-module, and may include both the first filtering sub-module and the second filtering sub-module. In addition, the number of the filtering sub-modules included in the LDO module is not limited, and for example, the first filtering sub-module may be included, and one or more first filtering sub-modules may be provided.

The above is an introduction of the LDO module, and the following describes the forward DCDC module.

Fig. 4 is a schematic structural diagram of a forward DCDC module provided in the embodiment of the present application, and as shown in fig. 4, the forward DCDC module includes a forward DCDC chip U8, an inductor L3, and a second switch sub-module. The input end VIN of the forward DCDC chip U8 is connected with the first end Main-PWR of the power supply module, the first output end LX of the forward DCDC chip U8 is connected with the first end of the inductor L3, and the second output end OUT of the forward DCDC chip U8 is connected with the first end of the rectifier sub-module and the first end E of the second switch sub-module. The second terminal F of the second switching sub-module is the output terminal of the positive-going DCDC module, i.e. the VCC terminal shown in fig. 4, which is used for connecting the second load, providing a fixed negative voltage, e.g. -2.5V.

The third end H of the second switch sub-module is connected with the second output end PWR_OP_CTL of the power supply control module, the fourth end I of the second switch sub-module is connected with the power supply module (MCU-3.0V), and the second end of the inductor L3 and the second end of the rectifier sub-module are grounded. The forward DCDC chip U8 converts the voltage of the power supply module into negative voltage through the inductor L3, and outputs the negative voltage from the second output end OUT of the forward DCDC chip U8.

The second output end OUT of the forward DCDC chip U8 outputs an alternating current signal with high frequency, the alternating current signal is converted into a direct current signal after being rectified and filtered by the rectifying sub-module, and then the direct current signal enters the second switching sub-module.

Illustratively, forward DCDC chip U8 includes a first output terminal LX, an enable terminal EX, and a mode switch terminal STB. The first output terminal LX is grounded through the inductor L3, and the second output terminal OUT of the forward DCDC chip U8 outputs a negative voltage.

The enable terminal EN is connected to a third output terminal (MCU-3.0V) of the power supply control module, and the third output terminal (MCU-3.0V) of the power supply control module inputs a high level (the high level is, for example, 3V) to the enable terminal EX, and may put the forward DCDC chip U8 in an enabled state to cause the forward DCDC chip U8 to perform a voltage conversion process.

It should be understood that the fourth output end of the power supply control module connected to the enable end EN of the forward DCDC chip and the third output end of the power supply control module connected to the second switch sub-module may be the same end, or may be different ends of the power supply control module. In addition, the power supply control module can be any module with a control function, such as a micro control unit (Microcontroller Unit; MCU), a singlechip, a processor and the like. Fig. 4 and fig. 3 each illustrate a port connected to each part of the forward DCDC module and a port connected to each part of the LDO module by taking the power supply control module as an MCU.

Optionally, a resistor R72 may be connected in series between the enable end EN and the third output end (MCU-3.0V) of the power supply control module, so as to implement current limiting through the resistor R72, avoid excessive current, damage the forward DCDC chip U8, play a role in protecting the forward DCDC chip U8, and improve the service life of the forward DCDC chip U8.

The mode switching terminal STB is connected to the fourth output terminal mcu_pwr_ctl of the fourth output terminal power control module of the power supply control module. When the fourth output end of the power supply control module supplies the fourth output end MCU_PWR_CTL of the control module to output high level, can control the forward DCDC chip U8 to work in the normal mode, the forward DCDC chip U8 can adopt a lower quiescent current to carry on the voltage conversion under 15uA in this mode; when the fourth output end of the power supply control module supplies the low level to the fourth output end MCU_PWR_CTL of the power supply control module, the forward DCDC chip U8 can be controlled to be switched into a standby mode, and the forward DCDC chip U8 can adopt lower quiescent current to realize voltage conversion in the standby mode. For example, the quiescent current of the forward DCDC chip U8 in the normal mode is lower than 15uA, and the quiescent current of the forward DCDC chip U8 in the standby mode is lower than 1uA. By means of the mode switching mode, lower quiescent current can be achieved, and therefore power consumption of the forward DCDC chip U8 is reduced.

Optionally, a resistor R74 may be connected in series between the mode switching end STB and the fourth output end mcu_pwr_ctl of the fourth output end power supply control module of the power supply control module, so as to implement current limiting through the resistor R74, avoid excessive current, damage the forward DCDC chip U8, play a role in protecting the forward DCDC chip U8, and improve the service life of the forward DCDC chip U8.

In one embodiment of the present application, the second switch submodule includes a first switch Q11, a second switch Q10, and a second resistor R34.

The first switch Q11 and the second switch Q10 may be turned on or off by a control signal, for example, a transistor, a MOS transistor, a thyristor, or the like. Fig. 4 is a schematic diagram of an example in which the first switch Q11 is a MOS transistor and the second switch Q10 is a triode.

The first end of the first switch Q11 is the first end E of the second switch sub-module, that is, the first end of the first switch Q11 is connected to the second output end OUT of the forward DCDC chip U8. The second terminal of the first switch Q11 is connected to the first terminal of the second switch Q10. The third terminal of the first switch Q11 is the second terminal F of the second switch sub-module, that is, the third terminal of the first switch Q11 is the output terminal VCC of the forward DCDC module, for connection with the second load. The second end of the second switch Q10 is the third end H of the second switch sub-module, namely the second end of the second switch Q10 is connected with the second output end PWR_OP_CTL of the power supply control module, the third end of the second switch Q10 is the fourth end I of the second switch sub-module, and is connected with the power supply module (MCU-3.0V).

For example, as shown in fig. 4, the first switch Q11 is a MOS transistor, and the second switch Q10 is a schematic diagram of a triode transistor. The source S of the MOS tube Q11 is connected with the second output end OUT of the forward DCDC chip U8, the grid G of the MOS tube Q11 is connected with the collector c of the triode Q10, one end of the drain D is connected with a second load, and the other end of the drain D is grounded. The second resistor R34 is connected in parallel between the source S and the gate G of the MOS transistor Q11. Optionally, the MOS transistor Q11 is connected to the triode Q10 through a resistor R76, where the resistor R76 is a current limiting resistor, and the drain D of the MOS transistor Q11 is grounded through a capacitor C29, so as to perform filtering processing on the voltage output by the forward DCDC module.

The base b of the triode Q10 is connected with the second output end PWR_OP_CTL of the power supply control module, and the emitter e of the triode Q10 is connected with the power supply module (MCU-3.0V). When the second output terminal pwr_op_ctl of the power supply control module outputs high level and the power supply module (MCU-3.0V) outputs high level, the transistor Q10 is turned off, the negative voltage changes the gate G of the MOS transistor Q11 to low level through the resistor R34, and at this time, the MOS transistor Q11 is turned off to stop supplying power to the second load. When the second output terminal pwr_op_ctl of the power supply control module is at a low level and the output of the power supply module (MCU-3.0V) is at a high level, the transistor Q10 is turned on, the collector c of the transistor Q10 becomes at a high level, and the gate G of the MOS transistor Q11 also becomes at a high level, at which time the MOS transistor Q11 is turned on. After the MOS tube Q11 is conducted, power supply to the second load is achieved through the filter capacitor C29.

In some embodiments, the second switch sub-module further comprises a second slow start sub-module.

Illustratively, the second slow start submodule includes a second capacitor C22 and a third resistor R76. The first end of the second capacitor C22 is connected to the first end E (for example, the MOS transistor in fig. 4 is the source S of the MOS transistor Q11) of the second switch submodule and the first end of the third resistor R76, and the second end of the second capacitor C22 is connected to the second end of the third resistor R76 and the second end F (for example, the MOS transistor in fig. 4 is the gate G of the MOS transistor Q11) of the second switch submodule, respectively.

That is, the second capacitor C22 is connected in parallel between the first end and the second end of the first switch Q11 (for example, between the source S and the gate G of the MOS transistor Q6 in fig. 3), that is, the voltage across the second capacitor C22 is equal to the voltage across the first end and the second end of the first switch (for example, the voltage across the gate G and the source S of the MOS transistor Q6). When the second capacitor C22 is not charged, the first switch Q11 is turned off; when the second capacitor C22 is fully charged, the first switch Q11 is turned on, and the charging time of the second capacitor C22 can delay the opening (i.e. closing) of the first switch Q11.

Because the second load using negative working voltage is usually a capacitive load, when the second switch submodule is turned on for a moment, a very large instant pulse circuit exists, and the second slow screwdriver module is designed in the circuit, so that transient current can be greatly reduced, damage of instantaneous heavy current to devices in the circuit can be avoided, protection of the circuit is realized, and the service life of each device is prolonged.

With continued reference to fig. 4, in an embodiment of the present application, the forward DCDC module may further include: fourth resistor R52 and fifth resistor R75.

The first end of the fourth resistor R52 is connected to the second output terminal OUT of the forward DCDC chip, the second end of the fourth resistor R52 is connected to the first end of the fifth resistor R75, and the second end of the fifth resistor R75 is connected to the first end E of the second switch sub-module.

The negative working voltage output of different magnitudes is realized by adjusting the magnitudes of the fourth resistor R52 and the fifth resistor R75 so as to meet the use requirements of various loads needing to use the negative working voltage. The power supply circuit can be specifically determined according to the load using the negative working voltage in the device using the power supply circuit, so that the power supply circuit can be adapted to the load requiring different negative working voltages.

Illustratively, the output value of the voltage of the forward DCDC module corresponds to the following formula with the fourth resistor R52 and the fifth resistor R75:

Vout＝-(1.2*R52/R75+1.2)。

with continued reference to fig. 4, in an embodiment of the present application, a third filtering sub-module may be further connected between the power supply module and the forward DCDC chip U8, so as to reduce ripple interference when the current output by the power supply module is input into the forward DCDC chip U8. The first end of the third filtering sub-module is connected with the input end VIN of the forward DCDC chip U8, and the second end of the third filtering sub-module is grounded. Or, the first end of the third filtering sub-module is connected with the first end Main-PWR of the power supply module, and the second end of the third filtering sub-module is grounded. Alternatively, the first end of the third filter sub-module is connected to any point between the first end Main-PWR of the power supply module and the input end VIN of the forward DCDC chip U8, and the second end of the third filter sub-module is grounded.

The third filtering sub-module may include a capacitor C83 and a capacitor C84, where the capacitor C83 and the capacitor C84 are connected in parallel, and one end of the capacitor C83 and one end of the capacitor C84 are connected between the power supply module and the forward DCDC chip U8, and the other end of the capacitor C83 and the other end of the capacitor C84 are grounded. For example, the capacitor C83 is a large capacitor, the capacitor C84 is a small capacitor, or the capacitor C83 is a small capacitor, and the capacitor C84 is a large capacitor, so as to filter high-frequency and low-frequency interference through the two capacitors.

The type and number of capacitances specifically included in the third filtering submodule are also not limited in the present application. For example, the third filtering sub-module may include at least one large capacitance, without a small capacitance. Alternatively, the third filtering sub-module may include at least one small capacitance, no large capacitance, or the third filtering sub-module may include at least one large capacitance, and at least one small capacitance, etc. Fig. 4 is a schematic diagram illustrating an example in which the third filtering submodule includes a large capacitor and a small capacitor.

The application also provides a flowmeter comprising a first load, a second load and any one of the power supply circuits; and the power supply circuit is used for providing positive working voltage for the first load and providing negative working voltage for the second load. The technical effects of the flowmeter can be found in the foregoing description and technical effects of the power supply circuit, and will not be described in detail.

The embodiment of the application solves the problem that the DCDC converter and the charge pump in the traditional design are high in power supply power consumption. According to the positive voltage output circuit, the LDO is used for voltage conversion, the quiescent current of the LDO is as low as 2uA, meanwhile, the voltage output circuit has extremely low ripple and noise, power consumption is reduced, and the accuracy of power supply voltage is improved. This application negative voltage output circuit adopts forward DCDC output negative voltage chip, and chip output pin passes through inductance ground connection, and the ground pin output negative voltage, and during operation quiescent current is less than 15uA, and the mode pin of steerable chip switches the operating condition of chip simultaneously, and sleep mode consumption is less than 1uA, can also adjust feedback resistance, and output different negative voltages has not only greatly reduced the consumption, and the suitability is stronger moreover. The positive voltage control circuit and the negative voltage control circuit respectively control the on and off of positive and negative voltages, and a slow-starting circuit is added in the control circuit, so that the circuit at the moment of starting is greatly reduced, the circuit is protected, and the power consumption is also reduced. The whole power supply circuit has low power consumption, simple circuit, high stability and low cost, and can meet the requirements of most flowmeter power supply systems.

It is to be understood that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (10)

1. A power supply circuit, comprising: the power supply module, the LDO module, the forward DCDC module and the power supply control module; the LDO module and the forward DCDC module are respectively connected with the power supply module and the power supply control module;

the power supply control module is used for controlling the LDO module to provide positive working voltage for the first load and controlling the positive DCDC module to provide negative working voltage for the second load.

2. The power supply circuit of claim 1, wherein the LDO module comprises: an LDO chip and a first switch submodule;

the first end of the power supply module is connected with the input end of the LDO chip, the output end of the LDO chip is connected with the first end of the first switch sub-module, the second end of the first switch sub-module is connected with the first output end of the power supply control module, the grounding end of the LDO chip is grounded, and the third end of the first switch sub-module is connected with the first load;

the LDO chip is used for converting the output voltage of the power supply module into forward working voltage;

the power supply control module is used for controlling the first switch submodule to switch on or off a power supply path between the LDO chip and the first load.

3. The power supply circuit of claim 2, wherein the LDO module further comprises: a first slow start sub-module for delaying power-up time; the first slow start submodule comprises: a first capacitor and a first resistor;

the first end of the first capacitor is connected with the first end of the first switch sub-module, the second end of the first capacitor is connected with the first end of the first resistor and the second end of the first switch sub-module respectively, and the second end of the first resistor is connected with the first output end of the power supply control module.

4. The power supply circuit of claim 2, wherein the LDO module further comprises: a first filtering sub-module and/or a second filtering sub-module;

the first end of the first filtering sub-module is connected with the input end of the LDO chip, and the second end of the first filtering sub-module is grounded;

the first end of the second filtering sub-module is connected with the output end of the LDO chip, and the second end of the second filtering sub-module is grounded.

5. The power supply circuit of any of claims 1-4, wherein the forward DCDC module comprises: the direct current DC (direct current) chip, an inductor, a second switch submodule and a rectifier submodule;

the first end of the power supply module is connected with the input end of the forward DCDC chip, the first output end of the forward DCDC chip is connected with the first end of the inductor, the second end of the inductor is connected with the second output end of the forward DCDC chip, the rectifier sub-module is connected with the first end of the second switch sub-module in series, the second end of the second switch sub-module is connected with the second load, the third end of the second switch sub-module is connected with the second output end of the power supply control module, the fourth end of the second switch sub-module is connected with the power supply module, and the second end of the inductor and the second end of the rectifier sub-module are respectively grounded;

the enabling end of the forward DCDC chip is connected with the third output end of the power supply control module, the mode switching end of the forward DCDC chip is connected with the fourth output end of the power supply control module, and the grounding end of the forward DCDC chip is grounded;

the positive DCDC chip is used for converting the output voltage of the power supply module into negative working voltage through the inductor and the rectifying sub-module;

and the power supply control module is used for controlling the second switch submodule to switch on or off a passage between the forward DCDC chip and the second load.

6. The power supply circuit of claim 5, wherein the second switch sub-module comprises: a first switch, a second switch, and a second resistor;

the first end of the first switch is the first end of the second switch sub-module, the second end of the first switch is connected with the first end of the second switch, and the third end of the first switch is the second end of the second switch sub-module;

the second end of the second switch is a third end of the second switch sub-module, and the third end of the second switch is a fourth end of the second switch sub-module; the first end of the second resistor is connected with the first end of the first switch, and the second end of the second resistor is connected with the second end of the first switch.

7. The power supply circuit of claim 6, wherein the forward DCDC module further comprises: the second is slowly opened submodule piece, the second is slowly opened submodule piece and is included: a second capacitor and a third resistor;

the second capacitor, the third resistor and the first switch are mutually connected in parallel.

8. The power supply circuit of claim 5, wherein the forward DCDC module further comprises: a fourth resistor and a fifth resistor;

the first end of the fourth resistor is connected with the second output end of the forward DCDC chip, the second end of the fourth resistor is connected with the first end of the fifth resistor, and the second end of the fifth resistor is connected with the first end of the second switch submodule.

9. The power supply circuit of claim 8, wherein the forward DCDC module further comprises: a third filtering sub-module;

the first end of the third filtering sub-module is connected with the input end of the forward DCDC module, and the second end of the third filtering sub-module is grounded.

10. A flow meter, the flow meter comprising: a first load, a second load, and a power supply circuit as claimed in any one of claims 1 to 9;

the power supply circuit is used for providing positive working voltage for the first load and providing negative working voltage for the second load.

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