Rtc backup power supply circuit, power terminal and power system

Abstract

The application relates to an RTC backup power supply circuit, a power terminal and a power system, wherein the RTC backup power supply circuit comprises a current-limiting resistor, a triode, a bias resistor and a bias resistor, one end of the current-limiting resistor is connected with a system voltage output end, a voltage output end of the RTC backup power supply circuit is connected with a power supply voltage input end of a clock chip, and the current-limiting resistor, the bias resistor and the triode interact to charge a super capacitor. Once the output voltage of the voltage output end of the clock chip power supply circuit is less than the output voltage of the voltage output end of the RTC backup power supply circuit, the clock chip is powered by the voltage output end of the RTC backup power supply circuit, so that the voltage output by the RTC backup power supply circuit can ensure the normal work of the clock chip when the voltage output of the clock chip power supply circuit (i.e. a clock battery) is low, the clock of the power terminal is accurate, and the maintenance cost of the power terminal is reduced.

Description

Technical Field

[0001] This invention relates to the field of power, and more particularly to an RTC backup power supply circuit, a power terminal, and a power system. Background Technology

[0002] With the continuous upgrading of power terminals and the introduction of standardized requirements for power terminals, clock accuracy has become an indispensable basic function of power terminals.

[0003] Currently, there are two ways for the CPU of a power terminal to obtain clock information: the first is a soft clock, and the second is a hard clock. Specifically, the CPU of a power terminal obtains the soft clock through the external power supply of the power terminal. The CPU reads the clock information of the metering MCU inside the power terminal via a serial port. However, when the power terminal is powered by an internal battery, the CPU cannot read the clock information of the metering MCU. In this case, the CPU can read the clock information of the clock chip inside the power terminal (i.e., the hard clock) through the I2C serial port. The clock chip is powered by a backup power supply, thus ensuring that the clock information of the power terminal is correct as long as the power terminal is running.

[0004] However, in existing power terminals, the backup power for clock chips mostly uses relatively expensive clock batteries, which are not rechargeable. Once the clock battery is depleted, it must be replaced with a new one, which increases the maintenance cost of the power terminal. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide an RTC backup power supply circuit that has low maintenance cost and can repeatedly power the clock chip in the power terminal, in contrast to the above-mentioned prior art.

[0006] The second technical problem to be solved by the present invention is to provide a power terminal that uses the above-mentioned RTC backup power circuit.

[0007] The third technical problem to be solved by the present invention is to provide a power system having the above-mentioned RTC backup power supply circuit.

[0008] The technical solution adopted by this invention to solve the first technical problem is: an RTC backup power supply circuit, suitable for power terminals with clock chip power supply circuits, characterized in that the RTC backup power supply circuit includes:

[0009] The current-limiting resistor R744 has its first terminal connected to the system voltage output terminal V1.

[0010] The collector of transistor V313 is connected to the first terminal of current-limiting resistor R744. The emitter of transistor V313 is connected to the first terminal of supercapacitor C409 and the positive terminal of first diode D1. The second terminal of supercapacitor C409 is connected to ground terminal GND. The negative terminal of first diode D1 and the voltage output terminal of clock chip power supply circuit are respectively connected to the power supply voltage input terminal of clock chip.

[0011] The bias resistor R745 has its first end connected to the system voltage output terminal V, and its second end connected to the base of the transistor V313.

[0012] The first end of the bias resistor R746 is connected to the second end of the bias resistor R745, and the second end of the bias resistor R746 is connected to the second terminal of the supercapacitor C409.

[0013] Improvedly, in the RTC backup power supply circuit, the clock chip power supply circuit includes:

[0014] The current-limiting resistor R367 has its first terminal connected to the system voltage output terminal V2.

[0015] The collector of transistor V316 is connected to the first terminal of current-limiting resistor R367, and the emitter of transistor V316 is connected to the positive terminal of a second diode D2; wherein, the negative terminal of the second diode D2 is connected to the power supply voltage input terminal of the clock chip.

[0016] The bias resistor R363 has its first end connected to the system voltage output terminal V2, and its second end connected to the base of the transistor V316.

[0017] The bias resistor R366 has its first end connected to the second end of the bias resistor R363, and the second end of the bias resistor R366 is connected to the ground terminal GND.

[0018] Furthermore, in the RTC backup power supply circuit, the system voltage output terminal V1 is 5.3V, the current limiting resistor R744 has a resistance of 1kΩ, the bias resistor R745 has a resistance of 6.8kΩ, the bias resistor R746 has a resistance of 9.1kΩ, and the supercapacitor C409 has a capacitance of 3.3EF.

[0019] In a further improvement, the transistor V313 in the RTC backup power supply circuit is model MMBT3904.

[0020] In a further improvement, in the RTC backup power supply circuit, the system voltage output terminal V2 is 4.8V, the current limiting resistor R367 has a resistance of 1kΩ, the bias resistor R363 has a resistance of 2kΩ, and the bias resistor R366 has a resistance of 3kΩ.

[0021] Furthermore, in the RTC backup power supply circuit, the transistor V316 is model MMBT3904.

[0022] The technical solution adopted by the present invention to solve the second technical problem is as follows: a power terminal using any one of the RTC backup power supply circuits has a clock chip power supply circuit, characterized in that the negative terminal of the first diode D1 in the RTC backup power supply circuit and the voltage output terminal of the clock chip power supply circuit are respectively connected to the power supply voltage input terminal of the clock chip.

[0023] Improvedly, in the power terminal, the clock chip power supply circuit is a clock battery.

[0024] Furthermore, in this invention, the power terminal is an electricity meter.

[0025] The technical solution adopted by the present invention to solve the third technical problem is: a power system, characterized in that it has any of the power terminals described in the present invention.

[0026] Compared with the prior art, the advantages of this invention are as follows: In the RTC backup power supply circuit of this invention, by adding a current-limiting resistor, a bias resistor, a transistor, and a supercapacitor, and connecting one end of the current-limiting resistor to the system voltage output terminal, and the voltage output terminal of the RTC backup power supply circuit to the power supply voltage input terminal of the clock chip, the interaction between the current-limiting resistor, the bias resistor, and the transistor charges the supercapacitor. Once the output voltage of the clock chip power supply circuit is lower than the output voltage of the RTC backup power supply circuit, the RTC backup power supply circuit supplies power to the clock chip. This ensures that even when the voltage output of the clock chip power supply circuit (i.e., the clock battery) is low, the voltage output of the RTC backup power supply circuit can still ensure the normal operation of the clock chip, ensuring the accuracy of the power terminal's clock, and also reducing the maintenance cost of the power terminal. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the setup of the RTC backup power supply circuit in the power terminal according to an embodiment of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] This embodiment provides an RTC backup power supply circuit 1, which is suitable for power terminals with a clock chip power supply circuit 2. Specifically, see [link to documentation]. Figure 1 As shown, the RTC backup power supply circuit 1 in this embodiment includes:

[0030] The current-limiting resistor R744 has its first terminal connected to the system voltage output terminal V1.

[0031] The collector of transistor V313 is connected to the first terminal of current-limiting resistor R744. The emitter of transistor V313 is connected to the first terminal of supercapacitor C409 and the positive terminal of first diode D1. The second terminal of supercapacitor C409 is connected to ground terminal GND. The negative terminal of first diode D1 and the voltage output terminal of clock chip power supply circuit are respectively connected to the power supply voltage input terminal of clock chip.

[0032] The bias resistor R745 has its first end connected to the system voltage output terminal V, and its second end connected to the base of the transistor V313.

[0033] The first end of the bias resistor R746 is connected to the second end of the bias resistor R745, and the second end of the bias resistor R746 is connected to the second terminal of the supercapacitor C409.

[0034] Specifically, in the RTC backup power supply circuit of this embodiment, the system voltage output V1 is 5.3V, the current-limiting resistor R744 has a resistance of 1kΩ, the bias resistor R745 has a resistance of 6.8kΩ, the bias resistor R746 has a resistance of 9.1kΩ, and the supercapacitor C409 has a capacitance of 3.3EF. The transistor V313 is a MMBT3904.

[0035] The following combination Figure 1 The working principle of the RTC backup power supply circuit in this embodiment is explained as follows:

[0036] The system voltage output terminal V1 provides power to the RTC backup power supply circuit. Current is limited by current-limiting resistor R744, and bias resistors R745 and R746 interact to provide a bias voltage to transistor V313, causing it to conduct and charge the downstream supercapacitor C409. The cathode of the first diode D1 is responsible for outputting the stored charge in supercapacitor C409 to the external clock chip that needs charging. For example, the cathode of the first diode D1 is connected to the power input pin VDD of the clock chip RX-8025T.

[0037] In this embodiment, see again Figure 1As shown, the clock chip power supply circuit 2 includes a current-limiting resistor R367, a transistor V316, a bias resistor R363, and a bias resistor R366. The first end of the current-limiting resistor R367 is connected to the system voltage output terminal V2. The collector of the transistor V316 is connected to the first end of the current-limiting resistor R367, and the emitter of the transistor V316 is connected to the anode of a second diode D2. The cathode of the second diode D2 is connected to the power supply voltage input terminal of the clock chip. The first end of the bias resistor R363 is connected to the system voltage output terminal V2, and the second end of the bias resistor R363 is connected to the base of the transistor V316. The first end of the bias resistor R366 is connected to the second end of the bias resistor R363, and the second end of the bias resistor R366 is connected to the ground terminal GND. The system voltage output terminal V2 is 4.8V, the current limiting resistor R367 has a resistance of 1kΩ, the bias resistor R363 has a resistance of 2kΩ, the bias resistor R366 has a resistance of 3kΩ, and the transistor V316 is a MMBT3904.

[0038] In addition, this embodiment also provides a power terminal using the aforementioned RTC backup power supply circuit. This power terminal has a clock chip power supply circuit, where the cathode of the first diode D1 in the RTC backup power supply circuit and the voltage output terminal of the clock chip power supply circuit are both connected to the power supply voltage input terminal of the clock chip. The clock chip power supply circuit is a clock battery, and the power terminal uses an electricity meter.

[0039] The following combination Figure 1 The principle of how the RTC backup power supply circuit and the clock chip power supply circuit work together in this embodiment to ensure normal power supply to the clock chip of the power terminal is explained:

[0040] Under normal circumstances, the clock chip power supply circuit provides normal power to the clock chip of the power terminal; the system voltage output terminal V1 provides power to the RTC backup power supply circuit, and then the current is limited by the current limiting resistor R744, and the bias resistors R745 and R746 interact to provide bias voltage to the transistor V313, thereby turning on the transistor V313, and then charging the supercapacitor C409 at the back end.

[0041] Because the voltage output terminals of the clock chip power supply circuit and the RTC backup power supply circuit (i.e., the negative terminal of the first diode D1) are both connected to the clock chip's power supply voltage input terminal (i.e., pin VDD): if the output voltage of the clock chip power supply circuit is greater than the output voltage of the RTC backup power supply circuit, then the clock chip power supply circuit will supply power to the clock chip, while the RTC backup power supply circuit will continue to store the current power or continue to charge the supercapacitor C409; if the output voltage of the clock chip power supply circuit is less than the output voltage of the RTC backup power supply circuit, then the clock chip power will be supplied by the RTC backup power supply circuit. This ensures that even when the voltage output of the clock chip power supply circuit (i.e., the clock battery) is low, the voltage output of the RTC backup power supply circuit can still be used to ensure the clock chip works normally, ensuring the accuracy of the power terminal's clock, and also reducing the maintenance cost of the power terminal.

[0042] In addition, this embodiment also provides a power system. Specifically, the power system has the power terminal described above.

[0043] Although preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An RTC backup power supply circuit, suitable for power terminals with clock chip power supply circuits, characterized in that, The RTC backup power supply circuit includes: The current-limiting resistor R744 has its first terminal connected to the system voltage output terminal V1. The collector of transistor V313 is connected to the first terminal of current-limiting resistor R744. The emitter of transistor V313 is connected to the first terminal of supercapacitor C409 and the positive terminal of first diode D1. The second terminal of supercapacitor C409 is connected to ground terminal GND. The negative terminal of first diode D1 and the voltage output terminal of clock chip power supply circuit are respectively connected to the power supply voltage input terminal of clock chip. The bias resistor R745 has its first end connected to the system voltage output terminal V, and its second end connected to the base of the transistor V313. The first end of the bias resistor R746 is connected to the second end of the bias resistor R745, and the second end of the bias resistor R746 is connected to the second terminal of the supercapacitor C409. The clock chip power supply circuit includes: The current-limiting resistor R367 has its first terminal connected to the system voltage output terminal V2. The collector of transistor V316 is connected to the first terminal of current-limiting resistor R367, and the emitter of transistor V316 is connected to the positive terminal of a second diode D2; wherein, the negative terminal of the second diode D2 is connected to the power supply voltage input terminal of the clock chip. The bias resistor R363 has its first end connected to the system voltage output terminal V2, and its second end connected to the base of the transistor V316. The bias resistor R366 has its first end connected to the second end of the bias resistor R363, and the second end of the bias resistor R366 is connected to the ground terminal GND.

2. The RTC backup power supply circuit according to claim 1, characterized in that, The system voltage output terminal V1 is 5.3V, the current limiting resistor R744 has a resistance of 1kΩ, the bias resistor R745 has a resistance of 6.8kΩ, the bias resistor R746 has a resistance of 9.1kΩ, and the supercapacitor C409 has a capacitance of 3.3EF.

3. The RTC backup power supply circuit according to claim 2, characterized in that, The transistor V313 is model MMBT3904.

4. The RTC backup power supply circuit according to any one of claims 1 to 3, characterized in that, The system voltage output terminal V2 is 4.8V, the current limiting resistor R367 has a resistance of 1kΩ, the bias resistor R363 has a resistance of 2kΩ, and the bias resistor R366 has a resistance of 3kΩ.

5. The RTC backup power supply circuit according to claim 4, characterized in that, The transistor V316 is model MMBT3904.

6. A power terminal using the RTC backup power supply circuit according to any one of claims 1 to 3, comprising a clock chip power supply circuit, characterized in that, The negative terminal of the first diode D1 in the RTC backup power supply circuit and the voltage output terminal of the clock chip power supply circuit are both connected to the power supply voltage input terminal of the clock chip.

7. The power terminal according to claim 6, characterized in that, The clock chip is powered by a clock battery.

8. The power terminal according to claim 7, characterized in that, The power terminal is an electricity meter.

9. A power system, characterized in that, It has a power terminal as described in any one of claims 6 to 8.

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