Stable power-on circuit and electricity meter

Abstract

The utility model discloses a stable power-on circuit and an electric meter, and relates to the technical field of power-on circuits. A DC-DC conversion circuit, wherein the DC-DC conversion circuit is electrically connected with the resistance-capacitance step-down circuit; the load module is electrically connected with the DC-DC conversion circuit, and the number of the load module is at least one; the input end of the power-on circuit is electrically connected with the resistance-capacitance step-down circuit, the output end of the power-on circuit is connected with the DC-DC conversion circuit, and when the output end of the power-on circuit outputs a power-on signal, the DC-DC conversion circuit works. According to the application, the power-on circuit is arranged to control the time-delay starting of the DC-DC conversion circuit so as to stabilize power-on, and the problem that a power metering product and the like are reset and even crashed due to the fact that the voltage of the direct-current power supply output by the resistance-capacitance step-down circuit slowly rises is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of power-on circuits, in particular to a stable power-on circuit and an electric meter. Background Art

[0002] Low-end electricity meters occupy a large market share in underdeveloped countries. These low-end meters have simple functions and can quickly enter the market and win by volume as long as they have a price advantage.

[0003] The RC step-down circuit is a circuit design method that converts AC mains power into low-voltage DC power. It is mainly used in situations where cost and volume are limited. It only requires a few simple devices: resistors, capacitors, diodes, etc. to achieve voltage reduction and output DC power. The cost is also very low, making it the preferred power supply solution for low-end electric meters.

[0004] For example, Chinese patent CN103389396B discloses a single-phase meter with far-infrared communication function and a metering method thereof, which converts the 220V power grid AC voltage into ±12V voltage after passing through a resistor-capacitor voltage-dropping circuit to output to a DC conversion circuit, and then connects the far-infrared communication circuit, the meter and the electric energy metering circuit and provides them with respective working voltages.

[0005] However, when an electric meter product using an RC power supply is just powered on, it takes some time for the VHH voltage value output by the RC step-down circuit to rise from 0V to the set value VHH0. However, when the voltage value rises, the DC conversion circuit has started working and outputting power. When the power is present, the metering module, storage module, communication module, etc. at the back end start working and there is a load. At this time, the VHH voltage output by the RC step-down circuit has not reached the set value VHH0 and cannot withstand the load at the back end, resulting in a drop in the VHH voltage. When the VHH voltage drops, the DC conversion circuit stops working and cannot supply power to the electrical load at the back end, resulting in a reset or freeze of the electric meter product, which can easily damage the electric metering product.

[0006] Therefore, it is urgent to develop a stable power-on circuit to solve the problems in the prior art. Utility Model Content

[0007] The purpose of the utility model is to provide a stable power-on circuit, which can stably power on to solve the problem raised in the above background technology that the DC power output by the RC step-down circuit rises slowly when power is turned on, causing power metering products to easily reset or even freeze.

[0008] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0009] A stable power-on circuit, comprising:

[0010] RC step-down circuit;

[0011] A DC-DC conversion circuit, the DC-DC conversion circuit is electrically connected to the RC step-down circuit;

[0012] A load module, the load module is electrically connected to the DC-DC conversion circuit, and at least one load module is provided;

[0013] A power-on circuit, wherein the input end of the power-on circuit is electrically connected to the RC step-down circuit, and the output end of the power-on circuit is connected to the DC-DC conversion circuit. When the output end of the power-on circuit outputs a power-on signal, the DC-DC conversion circuit works.

[0014] Furthermore, the power-on circuit is a delay control circuit.

[0015] Furthermore, the DC-DC conversion circuit includes a DC-DC chip, and the output end of the power-on circuit is connected to an enable pin of the DC-DC chip.

[0016] Furthermore, the power-on circuit includes a delay chip, a power pin of the delay chip is electrically connected to the output end of the RC step-down circuit; and an output pin of the delay chip is electrically connected to an enable pin of the DC-DC chip.

[0017] Furthermore, the output pin of the delay chip is connected to the base of the NPN transistor; the emitter of the NPN transistor is grounded, and the collector is connected to the base of the PNP transistor; the emitter of the PNP transistor is connected to the output end of the RC step-down circuit, and the collector is connected to the enable pin EN of the DC-DC chip.

[0018] Furthermore, the RC step-down circuit includes a varistor, one end of which is used to connect the live wire, and the other end is used to connect the neutral wire; the other end of the varistor is electrically connected to a resistor R148, the resistor R148 is connected in series with one end of the capacitor C136, the other end of the capacitor C136 is respectively connected to the cathode of the diode D117 and the anode of the diode D118, the anode of the diode D117 is connected to one end of the varistor, and the cathode of the diode D118 is connected to the output end of the RC step-down circuit; the cathode of the diode D118 is also electrically connected to the anode of the capacitor C137, the cathode of the capacitor C137 is connected to one end of the varistor and is grounded; the cathode of the diode D118 is also connected to the cathode of the voltage-stabilizing diode, and the anode of the voltage-stabilizing diode is connected to one end of the varistor.

[0019] Furthermore, a power pin of the DC-DC chip is connected to an output end of the RC step-down circuit and is grounded via a capacitor.

[0020] Furthermore, the third pin of the DC-DC chip is connected to the output end of the DC-DC conversion circuit through a resistor R158; the second pin is grounded and connected to the output end of the DC-DC conversion circuit through a capacitor C153, resistors R157 and resistor R158 respectively; the first pin is connected to the output end of the DC-DC conversion circuit through a capacitor C152 and an inductor L104; the sixth pin is connected to the output end of the DC-DC conversion circuit through an inductor L104; and the output end of the DC-DC conversion circuit is also grounded through a capacitor.

[0021] Furthermore, the load module includes a controller, a metering module, a storage module or a communication module.

[0022] An electric meter comprises the stable power-on circuit.

[0023] Compared with the prior art, the beneficial effect of the utility model is that a power-on circuit is set between the RC step-down circuit and the DC-DC conversion circuit to control the DC-DC conversion circuit to output a power-on signal to the DC-DC conversion circuit only when the power supply voltage value outputted at the output end of the RC step-down circuit is greater than or equal to the threshold voltage required for the normal operation of the rear-end load, so that when the output end of the RC step-down circuit is at low voltage, only the power-on circuit needs to be powered, and there is no need to power the rear-end load module, so as to avoid the problem of frequent power on and off caused by insufficient voltage.

[0024] At the same time, the present application is implemented through a delay control circuit: when the voltage outputted by the output end of the RC step-down circuit is greater than or equal to the threshold voltage, the output end of the power-on circuit outputs a power-on signal. By utilizing the characteristic that the voltage at the output end of the RC step-down circuit rises over time, the abnormality of the electric power meter caused by abnormal power grid environments such as the harsh power grid environment in some foreign countries and the high power-on and power-off frequency is effectively avoided. By prohibiting the DC-DC conversion circuit from powering on during the delay time, the frequent power-on and power-off phenomenon of the back-end load module caused by the power grid environment during the delay time is avoided.

[0025] Other features and advantages of the present invention will be disclosed in detail in the following specific implementations and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a circuit diagram of the power-on circuit of the utility model;

[0027] Figure 2 It is a circuit diagram of the RC step-down circuit of the utility model;

[0028] Figure 3 The utility model is a circuit diagram of a DC-DC conversion circuit. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Stable power-on circuit, such as Figures 1 to 3 As shown, including:

[0032] A RC step-down circuit, wherein the RC step-down circuit is used to be electrically connected to the mains;

[0033] A DC-DC conversion circuit, the DC-DC conversion circuit is electrically connected to the RC step-down circuit, and the DC-DC conversion circuit is used to supply power to the load module;

[0034] A load module, the load module is electrically connected to the DC-DC conversion circuit, and at least one load module is provided, and the load module includes a controller, a metering module, a storage module or a communication module, etc.;

[0035] A power-on circuit, wherein the input end of the power-on circuit is electrically connected to the RC step-down circuit, and the output end of the power-on circuit is electrically connected to the DC-DC conversion circuit. When the voltage output by the output end of the RC step-down circuit is greater than or equal to the threshold voltage, the output end of the power-on circuit outputs a power-on signal, and the DC-DC conversion circuit works; when the output end of the power-on circuit does not output a power-on signal, the DC-DC conversion circuit stops working.

[0036] In this embodiment, Figure 3 As shown, the DC-DC conversion circuit includes a DC-DC chip U120, and the output end of the power-on circuit is connected to the enable pin EN of the DC-DC chip U120. When the output end of the power-on circuit outputs a high-level signal, the DC-DC chip starts working, and when the output end of the power-on circuit does not output a power-on signal, the DC-DC chip stops working.

[0037] In this embodiment, Figure 1 As shown, the power-on circuit includes a delay chip IC17, and a power pin VDD of the delay chip IC17 is connected to the output end of the RC step-down circuit through a resistor R24.

[0038] The output pin OUT of the delay chip IC17 is connected to the base of the NPN transistor Q2 through the resistor R16, the emitter of the NPN transistor Q2 is grounded, the collector of the NPN transistor Q2 is connected to the base of the PNP transistor Q1 through the resistor R22, the emitter of the PNP transistor Q1 is connected to the output end of the RC step-down circuit, and the collector of the PNP transistor Q1 serves as the output end of the power-on circuit and is connected to the enable pin EN of the DC-DC chip.

[0039] In this embodiment, when the AC mains is powered on, the RC step-down circuit outputs a DC power supply VHH. When the DC power supply VHH is boosted for 100ms, the voltage is greater than or equal to 5V, and the delay chip IC17 is powered. The delay chip IC17 starts working. The delay time of the delay chip IC17 is 200ms, and the chip delays 200ms to output a high level. When the delay chip IC17 outputs a high level, the transistor Q2 is turned on, and the voltage of the resistor R22 is pulled down. The transistor Q1 is turned on, and the resistor R17 is directly pulled up on the DC power supply VHH to follow the VHH power supply voltage value. At this time, the DC-DC voltage chip enable pin EN is directly pulled up on the DC power supply VHH, and the DC-DC chip starts working, outputting a stable 3.3V power supply to power the power-consuming unit.

[0040] The delay time of the delay chip is set as needed. When the DC-DC conversion circuit is turned on after a delay of 200ms, the voltage value of VHH has reached 11.7V. At this time, the load capacity of VHH can fully meet the use of the back-end power load. This also solves the reset and crash problems of power metering products caused by the frequent power-on and power-off of the RC power supply solution.

[0041] The power supply pin VDD of the delay chip IC17 is also grounded through the capacitor C41, the resistor R24 ​​and the power supply pin VDD are also electrically connected to the cathode of the voltage zener diode ZD1, and the anode of the voltage zener diode ZD1 is grounded.

[0042] The RC step-down circuit may use an existing RC step-down circuit or the RC step-down circuit of this embodiment.

[0043] like Figure 2As shown, in this embodiment, the RC step-down circuit includes a varistor MOV105, one end of which is used to connect the live wire, and the other end is used to connect the neutral wire. The other end of the varistor MOV105 is connected to a resistor R148, which is connected in series with one end of the capacitor C136. The other end of the capacitor C136 is connected to the cathode of the diode D117 and the anode of the diode D118 respectively. The anode of the diode D117 is connected to one end of the varistor MOV105, and the cathode of the diode D118 is connected to the cathode of the voltage-stabilizing diode ZD108. The anode of the voltage-stabilizing diode ZD108 is connected to one end of the varistor MOV105. The cathode of the voltage-stabilizing diode ZD108 is also connected to the cathode of the capacitor C137, and is connected to the output end of the RC step-down circuit to output a VHH voltage. The cathode of the capacitor C137 is connected to the varistor MOV105 and is grounded.

[0044] The DC-DC conversion circuit may use an existing DC-DC conversion circuit.

[0045] like Figure 3 As shown, in this embodiment, the DC-DC conversion circuit includes a DC-DC chip U120. The fourth pin of the DC-DC chip U120 is an enable pin EN, which is used to connect to the output end of the power-on circuit; the fifth pin is a power pin, which is connected to the output end of the RC step-down circuit and is grounded through capacitors C1 and C151. The other pins of the DC-DC chip U120 are connected to the output end of the DC-DC conversion circuit to output the voltage required by the load module, which is 3.3V in this embodiment. Specifically, the third pin of the DC-DC chip U120 is connected to the output end of the DC-DC conversion circuit through a resistor R158; the second pin is grounded and connected to the output end of the DC-DC conversion circuit through capacitor C153, resistor R157 and resistor R158 respectively; the first pin is connected to the output end of the DC-DC conversion circuit through capacitor C152 and inductor L104; the sixth pin is connected to the output end of the DC-DC conversion circuit through inductor L104; and the output end of the DC-DC conversion circuit is also grounded through capacitor C154.

[0046] The utility model provides a stable power-on circuit with simple structure, convenient use and high reliability.

[0047] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0048] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A stable power-on circuit, characterized in that: include: RC step-down circuit; A DC-DC conversion circuit, the DC-DC conversion circuit is electrically connected to the RC step-down circuit; A load module, the load module is electrically connected to the DC-DC conversion circuit, and at least one load module is provided; A power-on circuit, wherein the input end of the power-on circuit is electrically connected to the RC step-down circuit, and the output end of the power-on circuit is electrically connected to the DC-DC conversion circuit. When the voltage output by the output end of the RC step-down circuit is greater than or equal to the threshold voltage, the output end of the power-on circuit outputs a power-on signal, and the DC-DC conversion circuit works.

2. The stable power-on circuit according to claim 1, characterized in that: The power-on circuit is a delay control circuit.

3. The stable power-on circuit according to claim 1, characterized in that: The DC-DC conversion circuit includes a DC-DC chip, and the output end of the power-on circuit is connected to an enable pin of the DC-DC chip.

4. The stable power-on circuit according to claim 3, characterized in that: The power-on circuit includes a delay chip, a power pin of the delay chip is electrically connected to the output end of the RC step-down circuit; and an output pin of the delay chip is electrically connected to an enable pin of a DC-DC chip.

5. The stable power-on circuit according to claim 4, characterized in that: The output pin of the delay chip is connected to the base of the NPN transistor; the emitter of the NPN transistor is grounded, and the collector is connected to the base of the PNP transistor; the emitter of the PNP transistor is connected to the output end of the RC step-down circuit, and the collector is connected to the enable pin EN of the DC-DC chip.

6. The stable power-on circuit according to any one of claims 1 to 5, characterized in that: The RC step-down circuit includes a varistor, one end of which is used to connect the live wire, and the other end is used to connect the neutral wire; the other end of the varistor is electrically connected to a resistor R148, the resistor R148 is connected in series with one end of a capacitor C136, the other end of the capacitor C136 is respectively connected to the cathode of a diode D117 and the anode of a diode D118, the anode of the diode D117 is connected to one end of the varistor, and the cathode of the diode D118 is connected to the output end of the RC step-down circuit; the cathode of the diode D118 is also electrically connected to the anode of the capacitor C137, the cathode of the capacitor C137 is connected to one end of the varistor and is grounded; the cathode of the diode D118 is also connected to the cathode of a voltage-stabilizing diode, and the anode of the voltage-stabilizing diode is connected to one end of the varistor.

7. The stable power-on circuit according to any one of claims 3 to 5, characterized in that: The power pin of the DC-DC chip is connected to the output end of the RC step-down circuit and is grounded through a capacitor.

8. The stable power-on circuit according to claim 7, characterized in that: The third pin of the DC-DC chip is connected to the output end of the DC-DC conversion circuit through a resistor R158; the second pin is grounded and connected to the output end of the DC-DC conversion circuit through a capacitor C153, resistors R157 and resistor R158 respectively; the first pin is connected to the output end of the DC-DC conversion circuit through a capacitor C152 and an inductor L104; the sixth pin is connected to the output end of the DC-DC conversion circuit through an inductor L104; the output end of the DC-DC conversion circuit is also grounded through a capacitor.

9. The stable power-on circuit according to any one of claims 1 to 5, characterized in that: The load module includes a controller, a metering module, a storage module or a communication module.

10. An electric meter, characterized in that The invention comprises the stable power-on circuit as described in any one of claims 1 to 9.

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