Power supply circuit

Abstract

The utility model relates to the technical field of main and standby power supply switching, and discloses a power supply circuit, which comprises a voltage conversion circuit, a voltage detection circuit and a switching circuit, and is characterized in that the input end of the voltage conversion circuit inputs the voltage of a first power supply, and the output end of the voltage conversion circuit is connected with the power supply end of a load and a second power supply; the input end of the voltage detection circuit inputs the voltage of the second power supply, and the output end of the voltage detection circuit is connected with the first end of the switching circuit; and the second end of the switching circuit is connected with the enabling end of the voltage conversion circuit. The device is simple in structure, low in cost, and high in reliability in the main and standby power switching process.

Description

Technical Field

[0001] This utility model relates to the field of main and backup power switching technology, specifically to a power supply circuit. Background Technology

[0002] Currently, in actual vehicles, the Telematics Box (TBOX) uses the vehicle's battery as the main power source and a nickel-metal hydride battery as a backup power source. This ensures that in the event of a main power failure, the TBOX can still make emergency calls and save and upload logs for a certain period of time. Taking three nickel-metal hydride batteries as an example, their nominal voltage is 3.6V, and an 8V output is provided on the TBOX board via a Boost converter chip. When the TBOX is working, the Boost chip remains enabled, and the 8V voltage is always maintained. When the main power voltage falls below a threshold, the main / backup power switching circuit automatically switches the primary power input from the main power source to 8V to ensure the TBOX continues to operate normally. Existing main / backup power switching circuits include... Figure 1 As shown, the following problems exist:

[0003] (1) When the TBOX is powered by the main power, two GPIO ports, MCU_IO1 and MCU_IO2, need to be allocated and kept high, which consumes a lot of MCU resources.

[0004] (2) The main power voltage detection and switching actions need to be performed sequentially, making the overall scheme relatively complex.

[0005] (3) MOSFETs Q3 and Q4 with larger overcurrent capacity need to be selected, which is more expensive. Utility Model Content

[0006] In view of this, the present invention provides a power supply circuit to solve the problem of complex structure of existing main and backup power switching circuits.

[0007] This utility model provides a power supply circuit, including: a voltage conversion circuit, a voltage detection circuit, and a switching circuit. The voltage conversion circuit receives the voltage of a first power source at its input terminal, and its output terminal is connected to the power supply terminal of the load and a second power source. The voltage detection circuit receives the voltage of the second power source at its input terminal, and its output terminal is connected to the first terminal of the switching circuit. The second terminal of the switching circuit is connected to the enable terminal of the voltage conversion circuit. When the voltage detection circuit determines that the voltage of the second power source is greater than or equal to a preset voltage, the switching circuit is turned off, causing the voltage conversion circuit to shut down its output, and the second power source supplies power to the load. When the voltage detection circuit determines that the voltage of the second power source is less than the preset voltage, the switching circuit is turned on, the voltage conversion circuit is enabled, and the voltage of the first power source is boosted to supply power to the load. The voltage of the first power source is less than the voltage of the second power source.

[0008] The power supply circuit provided by this utility model monitors the voltage of the second power source and switches the enable state of the voltage conversion circuit by switching the on / off state of the switching circuit. When the voltage of the second power source supplying power to the load is lower than the preset voltage, the switching circuit immediately turns on, causing the voltage conversion circuit to start working, boosting the voltage of the first power source to supply power to the load, and quickly switching the power supply. The switching circuit has a fast response speed, and the enable terminal of the voltage conversion circuit is connected to the switching circuit, directly switching the working state based on the on / off state of the switching circuit, without the need for an additional circuit to provide an enable signal, and the circuit structure is simple.

[0009] In one optional embodiment, the voltage conversion circuit includes: a voltage conversion chip and a first reverse protection unit, wherein the input terminal of the voltage conversion chip receives the voltage of a first power supply, the output terminal of the voltage conversion chip is connected to the first terminal of the first reverse protection unit, the enable terminal of the voltage conversion chip is connected to the second terminal of the switching circuit, and the second terminal of the first reverse protection unit is connected to the power supply terminal of the load.

[0010] In one optional implementation, the first anti-reverse unit includes: a first diode, the anode of the first diode being connected to the output terminal of the voltage conversion chip, and the cathode of the first diode being connected to the power supply terminal of the load.

[0011] In one optional embodiment, the switching circuit includes a switching unit and a voltage divider unit, wherein a first terminal of the voltage divider unit is connected to the output terminal of the voltage detection circuit, and a second terminal of the voltage divider unit is connected to the control terminal of the switching unit; the first terminal of the switching unit is connected to the enable terminal of the voltage conversion circuit, and the second terminal of the switching unit receives the voltage of a third power supply.

[0012] In one optional embodiment, the voltage divider unit includes: a first resistor, a second resistor, a second anti-reverse unit, and a third anti-reverse unit, wherein the first end of the second anti-reverse unit is connected to the output end of the voltage detection circuit, and the second end of the second anti-reverse unit is connected to the first end of the first resistor; the second end of the first resistor is connected to the first end of the third anti-reverse unit and the first end of the second resistor; the second end of the second resistor is grounded; and the second end of the third anti-reverse unit is connected to the control end of the switching unit.

[0013] In one optional implementation, the second anti-reverse unit includes: a second diode, the anode of the second diode being connected to the output terminal of the voltage detection circuit, and the cathode of the second diode being connected to the first terminal of the first resistor.

[0014] In one optional embodiment, the third anti-reverse unit includes: a third diode, the cathode of which is connected to the second terminal of the first resistor, and the anode of which is connected to the control terminal of the switching unit.

[0015] In one optional embodiment, the switching unit includes: a third resistor, a fourth resistor, and a controllable switch, wherein the control terminal of the controllable switch is connected to the second terminal of the voltage divider unit and the first terminal of the third resistor, the first terminal of the controllable switch is connected to the second terminal of the third resistor and the third power supply, the second terminal of the controllable switch is connected to the first terminal of the fourth resistor and the enable terminal of the voltage conversion circuit; and the second terminal of the fourth resistor is grounded.

[0016] In one alternative implementation, the switching circuit further includes a current limiting unit connected in series between the third power supply and the second terminal of the switching unit.

[0017] In one alternative implementation, the current limiting unit includes a fifth resistor. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a circuit diagram of the TBOX main / standby power switching circuit for related technologies;

[0020] Figure 2 This is a diagram illustrating the composition of a power supply circuit according to an embodiment of the present utility model;

[0021] Figure 3 This is a diagram illustrating the composition of another power supply circuit according to an embodiment of the present utility model;

[0022] Figure 4 This is a detailed circuit diagram of the power supply circuit according to an embodiment of the present utility model;

[0023] Figure 5 This is a diagram of another power supply circuit according to an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0028] Existing TBOX main / backup power switching circuits, such as Figure 1 As shown, MCU_IO1 and MCU_IO2 are GPIO pins output by the MCU. To achieve the main / standby power switching function, both pins need to be kept at a high level (3.3V). When the TBOX main power supply voltage is normal, due to the effect of diode D1 and resistor R2, the base voltage of PNP transistor Q1 is higher than the emitter voltage, so Q1 is cut off. Then Q2 is cut off, and PMOS transistors Q3 and Q4 are cut off. The first-stage power supply side is connected to the load and is powered by the main power supply.

[0029] When the main power supply voltage is lower than the switching threshold, the voltage difference between the base and emitter of Q1 after the main power supply voltage is divided by R3 and R4 can turn Q1 on. The collector voltage of Q1 is pulled up to close to 3.3V, the base of NPN transistor Q2 is pulled up, Q2 turns on, and then pulls down the gate voltage of PMOS transistors Q3 and Q4. After Q3 and Q4 are turned on, the load on the first-stage power supply side is powered by the 8V output of Boost, realizing the main and backup power switching.

[0030] However Figure 1When the circuit is powered by the main power supply, two GPIO ports, MCU_IO1 and MCU_IO2, need to be allocated and kept high, consuming significant MCU resources. Furthermore, the Boost voltage converter chip needs to be constantly enabled, meaning the Boost needs to continuously output 8V. After the detection module detects a drop in the main power voltage, it uses the physical characteristics of transistors and MOSFETs to switch the TBOX power supply path from the main power supply to the backup power supply via a switching module circuit. The main power voltage detection and switching actions are executed sequentially, making the overall solution relatively complex.

[0031] This utility model provides a power supply circuit, such as Figure 2 As shown, it includes: voltage conversion circuit 1, voltage detection circuit 2, and switching circuit 3.

[0032] Figure 2 In the circuit, the input terminal of voltage conversion circuit 1 receives the voltage of the first power supply, and the output terminal of voltage conversion circuit 1 is connected to the power supply terminal of the load and the second power supply.

[0033] Specifically, Figure 2 In this circuit, the first power supply is a backup power supply, and the second power supply is the primary power supply. In order to reduce circuit power consumption and save costs, the voltage of the first power supply is set to be lower than the voltage of the second power supply. At this time, the voltage conversion circuit 1 can be a DC-DC boost circuit, such as a BOOST circuit, which can boost the voltage of the first power supply to the voltage of the second power supply to provide backup power for the load.

[0034] Figure 2 In the circuit, the voltage of the second power supply is input to the input terminal of the voltage detection circuit 2, and the output terminal of the voltage detection circuit 2 is connected to the first terminal of the switching circuit 3.

[0035] Optionally, Figure 2 In this circuit, the voltage detection circuit 2 may include hardware structures such as amplifiers and comparators. One end of the comparator is input with a preset voltage. When the voltage detection circuit 2 determines that the voltage of the second power supply is greater than or equal to the preset voltage, it outputs a high level; when the voltage detection circuit 2 determines that the voltage of the second power supply is less than the preset voltage, it outputs a low level. The output logic of the level signal of the voltage detection circuit 2 can be set according to the actual needs of those skilled in the art.

[0036] Figure 2 In the circuit, the second terminal of the switching circuit 3 is connected to the enable terminal of the voltage conversion circuit 1.

[0037] Optionally, Figure 2 In the circuit 3, the switching circuit includes a transistor, with a MOSFET as an example.

[0038] Specifically, Figure 2In the process, when the voltage detection circuit 2 determines that the voltage of the second power supply is greater than or equal to the preset voltage, it indicates that the second power supply is in normal working condition without faults. The voltage detection circuit 2 outputs a high level, which turns off the switch circuit 3. After the voltage conversion circuit 1 shuts off its output, the second power supply directly supplies power to the load. When the voltage detection circuit 2 determines that the voltage of the second power supply is less than the preset voltage, it indicates that the second power supply is undervoltage. The voltage detection circuit 2 outputs a low level, which turns on the switch circuit 3. The voltage conversion circuit 1 is enabled and turns on, boosting the voltage of the first power supply to provide backup power to the load.

[0039] The power supply circuit provided in this embodiment monitors the voltage of the second power source and switches the enable state of the voltage conversion circuit by switching the on / off state of the switching circuit. When the voltage of the second power source supplying power to the load is lower than the preset voltage, the switching circuit immediately turns on, causing the voltage conversion circuit to start working, boosting the voltage of the first power source to supply power to the load, and quickly switching the power supply. The switching circuit has a fast response speed and a simple circuit structure.

[0040] In some alternative implementations, such as Figure 3 As shown, the voltage conversion circuit includes a voltage conversion chip 11 and a first anti-reverse unit 12. The input terminal of the voltage conversion chip 11 receives the voltage of the first power supply, the output terminal of the voltage conversion chip 11 is connected to the first terminal of the first anti-reverse unit 12, and the enable terminal of the voltage conversion chip 11 is connected to the second terminal of the switching circuit 3. The second terminal of the first anti-reverse unit 12 is connected to the power supply terminal of the load.

[0041] Optionally, Figure 3 In this context, the voltage conversion chip is a BOOST voltage conversion chip.

[0042] Specifically, Figure 4 In the first anti-reverse unit, there is a first diode D3, the anode of the first diode D3 is connected to the output terminal of the voltage conversion chip 11, and the cathode of the first diode D3 is connected to the power supply terminal of the load.

[0043] Specifically, Figure 4 In this circuit, the input terminal of the BOOST voltage converter chip U1 is connected to the backup battery, which serves as the primary power source. The input voltage of the primary power source is lower than that of the main power source. When the enable terminal of the BOOST voltage converter chip U1 is low, U1 shuts down its output. Therefore, there is no voltage on the anode side of the first diode D3, meaning there is no backup power source, and the load is powered solely by the main power source. When the enable terminal of the BOOST voltage converter chip U1 is high, U1 starts working, boosting the voltage of the primary power source to output the backup power source voltage. This backup power source voltage is then fed into the load via the first diode D3 to power the load.

[0044] In some alternative implementations, such as Figure 5 As shown, the switching circuit includes a switching unit 31 and a voltage divider unit 32. The first end of the voltage divider unit 32 is connected to the output end of the voltage detection circuit 2, and the second end of the voltage divider unit 32 is connected to the control end of the switching unit 31. The first end of the switching unit 31 is connected to the enable end of the voltage conversion circuit, and the second end of the switching unit 31 is input with the voltage of the third power supply.

[0045] Specifically, Figure 4 In the voltage divider unit, there are: a second anti-reverse unit composed of a first resistor R10, a second resistor R11, and a second diode D4, and a third anti-reverse unit composed of a third diode D5. The anode of the second diode D4 is connected to the output terminal of the voltage detection circuit 2, and the cathode of the second diode D4 is connected to the first terminal of the first resistor R10. The second terminal of the first resistor R10 is connected to the cathode of the third diode D5 and the first terminal of the second resistor R11. The second terminal of the second resistor R11 is grounded. The anode of the third diode D5 is connected to the control terminal of the switching unit 31.

[0046] Specifically, Figure 4 In the circuit, the switching unit 31 includes: a third resistor R9, a fourth resistor and a controllable switch Q5 with R12. The control terminal of the controllable switch Q5 is connected to the second terminal of the voltage divider unit 32 and the first terminal of the third resistor R9. The first terminal of the controllable switch Q5 is connected to the second terminal of the third resistor R9 and the third power supply. The second terminal of the controllable switch Q5 is connected to the first terminal of the fourth resistor R12 and the enable terminal of the BOOST voltage conversion chip U1. The second terminal of the fourth resistor R12 is grounded.

[0047] Specifically, Figure 4 In the process, when the voltage detection circuit 2 determines that the voltage of the main power supply is greater than or equal to the internal preset voltage, it outputs a high-level signal, sets the emitter of the controllable switch Q5 to be constantly high, and the high-level signal voltage is divided by the first resistor R10 and the second resistor R11, so that the base voltage of the controllable switch Q5 is higher than the emitter voltage, the controllable switch Q5 is turned off, the enable terminal of the BOOST voltage conversion chip U1 is low-level to disable the output, and no backup power supply is provided. The load is powered by the main power supply.

[0048] Specifically, Figure 4 In the process, when the voltage detection circuit 2 determines that the voltage of the main power supply is less than the internal preset voltage, the main power supply loses voltage and cannot provide normal operating voltage to the load. The voltage detection circuit 2 outputs a low-level signal. After the low-level signal voltage is divided by the first resistor R10 and the second resistor R11, the base voltage of the controllable switch Q5 is lower than the voltage difference between the base and emitter of Q5. The controllable switch Q5 is turned on, and the enable terminal of the BOOST voltage conversion chip U1 is pulled high and starts to work. The voltage of the backup battery is boosted and output as a backup power supply to power the load.

[0049] In some alternative implementations, such as Figure 4 As shown, the switching circuit also includes a current limiting unit consisting of a fifth resistor R8 connected in series between the third power supply and the second terminal of the switching unit.

[0050] Specifically, Figure 4 In the TBOX product, MCU_IO1 is the GPIO pin for outputting the MCU. To achieve the main power / backup power switching function, MCU_IO1 needs to be kept constantly high. When MCU_IO1 is constantly low, even if the main power supply fails, the TBOX will not switch to the backup power supply. This is the transportation mode, which is usually used when the TBOX product is transported to the vehicle after it has rolled off the production line, to avoid the backup battery being depleted due to the use of backup power during transportation.

[0051] It should be noted that this embodiment determines whether the main power supply is lost by using the turn-on condition of a PNP transistor, and automatically switches between main and backup power through hardware circuitry. Figure 1 Compared to the circuit shown, this embodiment utilizes the high-level state of MCU_IO1 and the turn-off logic of Q5 to simplify the main / standby power switching process, achieving synchronous detection and switching without the need for "detection first, then switching". Furthermore, this embodiment involves fewer electrical components, significantly reducing circuit cost.

[0052] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A power supply circuit, characterized in that, include: Voltage conversion circuit, voltage detection circuit and switching circuit, among which, The voltage of the first power supply is input to the input terminal of the voltage conversion circuit, and the output terminal of the voltage conversion circuit is connected to the power supply terminal of the load and the second power supply. The voltage of the second power supply is input to the input terminal of the voltage detection circuit, and the output terminal of the voltage detection circuit is connected to the first terminal of the switching circuit. The second terminal of the switching circuit is connected to the enable terminal of the voltage conversion circuit; When the voltage detection circuit determines that the voltage of the second power supply is greater than or equal to the preset voltage, the switching circuit is turned off, so that after the voltage conversion circuit shuts off its output, the second power supply supplies power to the load; When the voltage detection circuit determines that the voltage of the second power supply is less than the preset voltage, the switching circuit is turned on, and the voltage conversion circuit is enabled to boost the voltage of the first power supply to supply power to the load. The voltage of the first power source is less than the voltage of the second power source.

2. The power supply circuit according to claim 1, characterized in that, The voltage conversion circuit includes: a voltage conversion chip and a first anti-reverse unit, wherein... The voltage of the first power supply is input to the input terminal of the voltage conversion chip, the output terminal of the voltage conversion chip is connected to the first terminal of the first anti-reverse unit, and the enable terminal of the voltage conversion chip is connected to the second terminal of the switching circuit. The second end of the first anti-reverse unit is connected to the power supply end of the load.

3. The power supply circuit according to claim 2, characterized in that, The first anti-reverse unit includes: a first diode, The anode of the first diode is connected to the output terminal of the voltage conversion chip, and the cathode of the first diode is connected to the power supply terminal of the load.

4. The power supply circuit according to claim 1, characterized in that, The switching circuit includes: a switching unit and a voltage divider unit, wherein... The first end of the voltage divider unit is connected to the output end of the voltage detection circuit, and the second end of the voltage divider unit is connected to the control end of the switching unit. The first terminal of the switching unit is connected to the enable terminal of the voltage conversion circuit, and the second terminal of the switching unit is input with the voltage of the third power supply.

5. The power supply circuit according to claim 4, characterized in that, The voltage divider unit includes: a first resistor, a second resistor, a second anti-reverse unit, and a third anti-reverse unit, wherein, The first end of the second anti-reverse unit is connected to the output end of the voltage detection circuit, and the second end of the second anti-reverse unit is connected to the first end of the first resistor; The second end of the first resistor is connected to the first end of the third anti-reverse unit and the first end of the second resistor; The second terminal of the second resistor is grounded; The second end of the third anti-reverse unit is connected to the control end of the switch unit.

6. The power supply circuit according to claim 5, characterized in that, The second anti-reverse unit includes: a second diode, The anode of the second diode is connected to the output terminal of the voltage detection circuit, and the cathode of the second diode is connected to the first terminal of the first resistor.

7. The power supply circuit according to claim 5, characterized in that, The third anti-reverse unit includes: a third diode, The cathode of the third diode is connected to the second end of the first resistor, and the anode of the third diode is connected to the control terminal of the switching unit.

8. The power supply circuit according to claim 4, characterized in that, The switching unit includes: a third resistor, a fourth resistor, and a controllable switch, wherein, The control terminal of the controllable switch is connected to the second terminal of the voltage divider unit and the first terminal of the third resistor. The first terminal of the controllable switch is connected to the second terminal of the third resistor and the third power supply. The second terminal of the controllable switch is connected to the first terminal of the fourth resistor and the enable terminal of the voltage conversion circuit. The second terminal of the fourth resistor is grounded.

9. The power supply circuit according to claim 4, characterized in that, The switching circuit also includes: A current limiting unit is connected in series between the third power supply and the second terminal of the switching unit.

10. The power supply circuit according to claim 9, characterized in that, The current limiting unit includes: a fifth resistor.

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