Low-cost standby battery charging and discharging and switching circuit

Abstract

The utility model discloses a low-cost standby battery charging and discharging and switching circuit, which mainly solves the problems of low cost and short service life of the existing switching circuit. The circuit comprises a voltage-stabilizing power supply circuit, a charging circuit connected with the voltage-stabilizing power supply circuit, a standby battery B1 connected with the charging circuit, an auxiliary power supply circuit connected with the standby battery, and a main power supply circuit connected with the auxiliary power supply circuit through a change-over switch. Through the above design, the electronic switch composed of the low-cost universal charging management IC CN3130 and the discrete triode and MOS is used, the external power supply is used under the condition that the equipment has external power supply, and after the external power supply is powered down, the external power supply is switched to the internal standby battery for power supply. Therefore, the equipment or the core circuit part is ensured to maintain working.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and in particular relates to a low-cost backup battery charging, discharging and switching circuit. Background Art

[0002] At present, high-reliability electronic equipment itself or some important functional circuits of the product need to maintain working for a period of time after power failure, which requires the use of backup batteries and the like to provide power. At this time, dual power switching is required. When the external power supply is normal, the external power supply is used. When the external power supply is off, the backup battery is used for power supply. Once the external power supply is normal, it can automatically switch back to the external power supply.

[0003] At present, ordinary dual-battery switching circuits have various shortcomings, such as poor switching stability and probabilistic failure; complex logic that even affects the charging function; poor practicality, requiring the screen to be turned off and the current to be low before the switch can be successful; expensive materials that increase costs; or incorrect switching that causes the built-in small battery to be over-discharged and affects its service life. Utility Model Content

[0004] The utility model aims to provide a low-cost backup battery charging, discharging and switching circuit, mainly to solve the problems of cost and short service life of the existing switching circuit.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A low-cost backup battery charging, discharging and switching circuit includes a voltage-stabilizing power supply circuit, a charging circuit connected to the voltage-stabilizing power supply circuit, a backup battery B1 connected to the charging circuit, an auxiliary power supply circuit connected to the backup battery, and a main power supply circuit connected to the auxiliary power supply circuit via a switching switch.

[0007] Furthermore, in the utility model, the auxiliary power supply circuit includes a transistor Q4 whose base is connected to 3.3VD_MAIN and whose emitter is grounded, a resistor R7 whose one end is connected to the collector of the transistor Q4 and whose other end is connected to the positive electrode of the backup battery, a transistor Q5 whose base is connected to the collector of the transistor Q4 and whose emitter is grounded, a PMOS tube Q3 whose gate is connected to the collector of the transistor Q5, a resistor R6 connected between the gate and the drain of the PMOS tube Q3, and a capacitor C9 whose one end is connected to the drain of the PMOS tube Q3 and whose other end is grounded; wherein the drain of the PMOS tube Q3 is also connected to the positive electrode of the backup battery B1; the source of the PMOS tube Q3 is connected to VDD_MCU for realizing auxiliary power supply of the MCU.

[0008] Furthermore, in the present invention, the main power supply circuit is composed of a voltage conversion chip U2 and an output filter capacitor C6 connected to the output end of the voltage conversion chip U2 and grounded at the other end; the output end of the voltage conversion chip U2 is connected to the 3.3VD_MAIN port and the switching switch.

[0009] Furthermore, in the utility model, the switching switch includes a switch tube Q2 whose drain is connected to the output end of the voltage conversion chip U2 and whose source is connected to VDD_MCU for realizing power supply of the MCU, a resistor R5 whose one end is connected to the gate of the switch tube Q2 and the other end is connected to the base, and a resistor R4 whose one end is connected to the gate of the switch tube Q2 and the other end is connected to the power input 12V_IN.

[0010] Further, in the utility model, the voltage-stabilized power supply circuit includes a DCJACK input J1 for connecting to a 12V power supply, a capacitor C5 having one end connected to the first port of the DC JACK input J1 and the other end grounded, a capacitor C4 having one end connected to the first port of the DC JACK input J1 and the power input 12V_IN terminal and the other end grounded, a voltage-stabilizing diode D1 having a positive electrode connected to the ground end of the capacitor C4, a resistor R3 having one end connected to the negative electrode of the voltage-stabilizing diode D1 and the other end connected to the first port of the DC JACK input J1, a transistor Q1 having a base connected to the negative electrode of the voltage-stabilizing diode D1 and a collector connected to the first port of the DC JACK input J1, and a capacitor C3 having one end connected to the emitter of the transistor Q1 and the other end grounded; wherein the collector of the transistor Q1 is also connected to the charging circuit.

[0011] Furthermore, in the utility model, the charging circuit includes a charging IC chip U1 whose 4th port is connected to the collector of the transistor Q1, a resistor R2 whose one end is connected to the 6th port of the charging IC chip U1 and the other end is grounded, a resistor R1 connected between the 2nd and 3rd ports of the charging IC chip U1, a capacitor C1 whose one end is connected to the 3rd port of the charging IC chip U1 and the other end is grounded, and a capacitor C2 whose one end is connected to the 3rd port of the charging IC chip U1 and the other end is grounded; wherein, the 3rd port of the charging IC chip U1 is also connected to the positive electrode of the backup battery B1.

[0012] Compared with the prior art, the utility model has the following beneficial effects:

[0013] (1) The utility model uses a low-cost universal charging management IC CN3130 and an electronic switch composed of discrete transistors and MOS, which can achieve high reliability when the device is powered by an external power supply. When the external power supply fails, it switches to the internal backup battery power supply, thereby ensuring that the device or the core circuit part can maintain operation.

[0014] (2) The utility model uses low-cost universal components and circuit design to achieve high reliability of charging and power-off switching of the backup battery, and is therefore worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the circuit connection relationship between the voltage-stabilizing power supply circuit, the charging circuit and the backup battery in the embodiment of the utility model.

[0016] Figure 2 This is a schematic diagram of the connection relationship between the auxiliary power supply circuit, the switching switch, and the auxiliary power supply circuit in the embodiment of the utility model. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The present invention includes but is not limited to the following embodiments.

[0018] Example

[0019] like Figure 1 , 2 As shown, the utility model discloses a low-cost backup battery charging, discharging and switching circuit, including a voltage-stabilizing power supply circuit, a charging circuit connected to the voltage-stabilizing power supply circuit, a backup battery B1 connected to the charging circuit, an auxiliary power supply circuit connected to the backup battery, and a main power supply circuit connected to the auxiliary power supply circuit through a switching switch.

[0020] In this embodiment, the auxiliary power supply circuit includes a transistor Q4 with a base connected to 3.3VD_MAIN and an emitter grounded, a resistor R7 with one end connected to the collector of the transistor Q4 and the other end connected to the positive electrode of the backup battery, a transistor Q5 with a base connected to the collector of the transistor Q4 and an emitter grounded, a PMOS transistor Q3 with a gate connected to the collector of the transistor Q5, a resistor R6 connected between the gate and the drain of the PMOS transistor Q3, and a capacitor C9 with one end connected to the drain of the PMOS transistor Q3 and the other end grounded; wherein the drain of the PMOS transistor Q3 is also connected to the positive electrode of the backup battery B1; the source of the PMOS transistor Q3 is connected to VDD_MCU for realizing the auxiliary power supply of the MCU. Among them, the transistors Q4 and Q5 are both NPN transistors with a model of MMBT3904. The model of the PMOS transistor Q3 is CES2312.

[0021] In this embodiment, the main power supply circuit is composed of a voltage conversion chip U2 and an output filter capacitor C6 connected to the output end of the voltage conversion chip U2 and the other end is grounded; the output end of the voltage conversion chip U2 is connected to the 3.3VD_MAIN port and the switching switch.

[0022] In this embodiment, the switch includes a switch tube Q2 whose drain is connected to the output end of the voltage conversion chip U2 and whose source is connected to VDD_MCU for realizing the power supply of the MCU, a resistor R5 whose one end is connected to the gate of the switch tube Q2 and whose other end is connected to the base, and a resistor R4 whose one end is connected to the gate of the switch tube Q2 and whose other end is connected to the power input 12V_IN. The switch tube Q2 is an NMOS tube of model CEN2321A.

[0023] In this embodiment, the voltage-stabilized power supply circuit includes a DC JACK input J1 for accessing a 12V power supply, a capacitor C5 having one end connected to the first port of the DC JACK input J1 and the other end grounded, a capacitor C4 having one end connected to the first port of the DC JACK input J1 and the power input 12V_IN end and the other end grounded, a voltage-stabilizing diode D1 having a positive electrode connected to the grounded end of the capacitor C4, a resistor R3 having one end connected to the negative electrode of the voltage-stabilizing diode D1 and the other end connected to the first port of the DC JACK input J1, a transistor Q1 having a base connected to the negative electrode of the voltage-stabilizing diode D1 and a collector connected to the first port of the DC JACK input J1, and a capacitor C3 having one end connected to the emitter of the transistor Q1 and the other end grounded; wherein the collector of the transistor Q1 is also connected to the charging circuit. wherein the model of the transistor Q1 is an NPN transistor of MMBT3904. the model of the voltage-stabilizing diode D1 is BZT52C5V6.

[0024] In this embodiment, the charging circuit includes a charging IC chip U1 of model CN3130 whose 4th port is connected to the collector of the transistor Q1, a resistor R2 whose one end is connected to the 6th port of the charging IC chip U1 and the other end is grounded, a resistor R1 connected between the 2nd and 3rd ports of the charging IC chip U1, a capacitor C1 whose one end is connected to the 3rd port of the charging IC chip U1 and the other end is grounded, and a capacitor C2 whose one end is connected to the 3rd port of the charging IC chip U1 and the other end is grounded; wherein, the 3rd port of the charging IC chip U1 is also connected to the positive electrode of the backup battery B1.

[0025] The working principle of this embodiment is as follows: 12V power supply is input through J1 DC JACK, capacitors C3 and C4 are DC12V input filter capacitors, and through transistor Q1, 5.6V voltage regulator diode D1 and R3 current limiting resistor, a stable 5V voltage regulator power supply is formed to power the charging IC chip U1, R1 is the charging voltage setting resistor, and R2 is the charging current setting resistor. The charging voltage and charging current can be reasonably set according to their own needs. C1 and C2 are battery filter capacitors, and B1 is a 3.6V battery in this embodiment. When the battery is lower than 3.59V, U1 charges the battery.

[0026] U2 is a DC12V to 3.3V DCDC Buck Converter. When powered by DC12V, Q2 is turned on and outputs 3.3V to power the MCU. Capacitors C7 and C8 are MCU 3.3V filter capacitors. At the same time, Q4 is turned on, Q5 is turned off, and PMOS tube Q3 is turned off. The battery Vbat does not output electricity. The MCU is powered by DC12V converted to 3.3V by U2, thus saving battery usage.

[0027] When the external power is off, U2 3.3VD_MAIN has no output, transistor Q4 is turned off, transistor Q5 is turned on, and PMOS tube Q3 is turned on. The battery Vbat outputs power to the MCU. At the same time, NMOS tube Q2 is turned off and will not reversely power U2.

[0028] This example takes the input of 12V, the battery of 3.6V, and the output of 3.3V as an example, but it is not limited to this application. Different voltage ranges can be flexibly selected and set according to your actual situation.

[0029] Through the above design, the utility model uses a low-cost universal charging management IC CN3130 and an electronic switch composed of discrete transistors and MOS, and highly reliably realizes the use of external power supply when the device has external power supply, and switches to internal backup battery power supply after the external power supply fails, thereby ensuring that the device or part of the core circuit maintains operation.

[0030] The above embodiment is only one of the preferred implementation modes of the present utility model and should not be used to limit the protection scope of the present utility model. Any changes or modifications that are made to the main design concept and spirit of the present utility model without any substantive significance, as long as the technical problems solved are still consistent with the present utility model, should be included in the protection scope of the present utility model.

Claims

1. A low-cost backup battery charging, discharging and switching circuit, characterized in that: It includes a voltage-stabilized power supply circuit, a charging circuit connected to the voltage-stabilized power supply circuit, a backup battery B1 connected to the charging circuit, an auxiliary power supply circuit connected to the backup battery, and a main power supply circuit connected to the auxiliary power supply circuit through a switching switch; The auxiliary power supply circuit includes a transistor Q4 whose base is connected to 3.3VD_MAIN and whose emitter is grounded, a resistor R7 whose one end is connected to the collector of the transistor Q4 and whose other end is connected to the positive electrode of the backup battery, a transistor Q5 whose base is connected to the collector of the transistor Q4 and whose emitter is grounded, a PMOS transistor Q3 whose gate is connected to the collector of the transistor Q5, a resistor R6 connected between the gate and the drain of the PMOS transistor Q3, and a capacitor C9 whose one end is connected to the drain of the PMOS transistor Q3 and whose other end is grounded; wherein the drain of the PMOS transistor Q3 is also connected to the positive electrode of the backup battery B1; the source of the PMOS transistor Q3 is connected to VDD_MCU for realizing auxiliary power supply of the MCU; The main power supply circuit is composed of a voltage conversion chip U2 and an output filter capacitor C6 connected to the output end of the voltage conversion chip U2 and the other end is grounded; the output end of the voltage conversion chip U2 is connected to the 3.3VD_MAIN port and the switching switch; The switching switch includes a switch tube Q2 whose drain is connected to the output end of the voltage conversion chip U2 and whose source is connected to VDD_MCU for powering the MCU, a resistor R5 whose one end is connected to the gate of the switch tube Q2 and the other end is connected to the base, and a resistor R4 whose one end is connected to the gate of the switch tube Q2 and the other end is connected to the power input 12V_IN.

2. A low-cost backup battery charging, discharging and switching circuit according to claim 1, characterized in that: The voltage-stabilized power supply circuit includes a DC JACK input J1 for connecting to a 12V power supply, a capacitor C5 having one end connected to the first port of the DC JACK input J1 and the other end grounded, a capacitor C4 having one end connected to the first port of the DC JACK input J1 and the power input 12V_IN terminal and the other end grounded, a voltage-stabilizing diode D1 having a positive electrode connected to the grounded end of the capacitor C4, a resistor R3 having one end connected to the negative electrode of the voltage-stabilizing diode D1 and the other end connected to the first port of the DC JACK input J1, a transistor Q1 having a base connected to the negative electrode of the voltage-stabilizing diode D1 and a collector connected to the first port of the DC JACK input J1, and a capacitor C3 having one end connected to the emitter of the transistor Q1 and the other end grounded; wherein the collector of the transistor Q1 is also connected to a charging circuit.

3. A low-cost backup battery charging, discharging and switching circuit according to claim 2, characterized in that: The charging circuit includes a charging IC chip U1 whose 4th port is connected to the collector of the transistor Q1, a resistor R2 whose one end is connected to the 6th port of the charging IC chip U1 and the other end is grounded, a resistor R1 connected between the 2nd and 3rd ports of the charging IC chip U1, a capacitor C1 whose one end is connected to the 3rd port of the charging IC chip U1 and the other end is grounded, and a capacitor C2 whose one end is connected to the 3rd port of the charging IC chip U1 and the other end is grounded; wherein, the 3rd port of the charging IC chip U1 is also connected to the positive electrode of the backup battery B1.

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