Backup battery undervoltage management circuit and method

Abstract

The present invention discloses a backup battery undervoltage management circuit and method, comprising: an MCU circuit, an OR gate circuit, a battery voltage detection circuit, a resistor voltage divider circuit and a switch circuit; the MCU circuit sets a high or low level for a first output terminal and a second output terminal according to the working state of a vehicle-mounted terminal and / or the detected backup battery power; the OR gate circuit is used to determine whether a high level is output; the battery voltage detection circuit is respectively connected to the backup battery, the MCU circuit, and the OR gate circuit to detect whether the backup battery is undervoltage; the resistor voltage divider circuit is arranged between the backup battery and the MCU circuit, and when the vehicle-mounted terminal is not in a dormant state, the MCU circuit detects the output of the resistor voltage divider circuit; the switch circuit is arranged between the OR gate circuit and the backup battery, and controls whether to power the MCU through the OR gate circuit. The present invention can accurately and timely detect whether the backup battery is undervoltage, and perform corresponding actions to turn off or on the backup battery.

Description

Technical Field

[0001] The present invention relates to the technical field of backup battery management, and in particular to a backup battery undervoltage management circuit and method. Background Art

[0002] At present, most vehicle terminals have a backup battery power supply function. Reliable backup battery undervoltage management can not only ensure the stable operation of the core module after the main power supply is cut off, but also effectively prevent battery damage caused by backup battery undervoltage. Therefore, the reliability of the backup battery undervoltage management system is of great importance. In the existing detection method, the detection of the backup battery power in sleep mode is not real-time, and RTC timed wake-up detection is required. On the one hand, it increases the standby power consumption; on the other hand, it increases the difficulty of software development; on the third hand, between two adjacent undervoltage detections, the battery may have been undervoltage, and some functional modules of the vehicle terminal (such as the communication module) will be abnormally shut down. At this time, the external power supply is powered on, which will cause a startup timing error, resulting in failure to start up in time, or failure to start up. In addition, the existing detection method cannot filter out the backup battery voltage fluctuation caused by load fluctuations, resulting in misjudgment. Summary of the invention

[0003] The main purpose of the present invention is to provide a backup battery undervoltage management circuit and method, which can accurately and timely detect whether the backup battery is undervoltage and perform corresponding actions to turn off or turn on the backup battery.

[0004] The present invention adopts the following technical solution:

[0005] On the one hand, a backup battery undervoltage management circuit includes: an MCU circuit, an OR gate circuit, a battery voltage detection circuit, a resistor voltage divider circuit and a switch circuit;

[0006] The MCU circuit comprises a first output terminal and a second output terminal; the MCU circuit sets the first output terminal and the second output terminal to a high or low level according to the working state of the vehicle-mounted terminal and / or the detected backup battery power;

[0007] The OR gate circuit comprises a first input terminal, a second input terminal and an output terminal; the first input terminal of the OR gate circuit is connected to the first output terminal of the MCU circuit; the second input terminal of the OR gate circuit is connected to the voltage detection output terminal of the battery voltage detection circuit; the output terminal of the OR gate circuit is connected to the switch circuit;

[0008] The battery voltage detection circuit has a down-threshold input terminal connected to the backup battery; a power input terminal connected to the second output terminal of the MCU circuit; and a voltage detection output terminal connected to the second input terminal of the OR gate circuit;

[0009] The resistor voltage divider circuit is arranged between the backup battery and the MCU circuit, and when the vehicle-mounted terminal is not in a dormant state, the MCU circuit detects the output of the resistor voltage divider circuit;

[0010] The switch circuit is arranged between the OR gate circuit and the backup battery, and controls whether to supply power to the MCU through the OR gate circuit.

[0011] Preferably, the OR gate circuit includes a first diode and a second diode; the anode of the first diode is connected to the MCU circuit, and the anode of the second diode is connected to the battery voltage detection circuit; the cathode of the first diode and the cathode of the second diode are both connected to the switch circuit.

[0012] Preferably, the battery voltage detection circuit includes a battery voltage detection chip; the down threshold input terminal of the battery voltage detection chip is connected to the backup battery through a second resistor, and its power input terminal is connected to the second output terminal of the MCU circuit; and its voltage detection output terminal is connected to the second input terminal of the OR gate circuit.

[0013] Preferably, the battery voltage detection circuit includes a filter circuit; the filter circuit is connected to the backup battery through a second resistor and a third resistor; the filter circuit includes a fourth resistor and a first capacitor connected in parallel.

[0014] Preferably, the resistance divider circuit includes a fifth resistor, a sixth resistor and a second capacitor; one end of the fifth resistor is connected to the backup battery, and the other end is respectively connected to one end of the sixth resistor, one end of the second capacitor and the input end of the MCU circuit; the sixth resistor and the second capacitor are connected in parallel.

[0015] Preferably, the switch circuit includes a transistor; the base of the transistor is connected to the output end of the OR gate circuit; the emitter of the transistor is grounded; and the collector of the transistor is connected to the backup battery via a first resistor.

[0016] Preferably, the switch circuit further includes a MOS tube; the gate of the MOS tube is connected to the collector of the transistor; the source of the MOS tube is connected to the backup battery; and the drain of the MOS tube is connected to the MCU circuit.

[0017] On the other hand, the present invention provides a backup battery undervoltage management method, based on the backup battery undervoltage management circuit, comprising:

[0018] S101, the vehicle terminal starts the backup battery to supply power, and the MCU circuit controls the first output terminal and the second output terminal to output a high level;

[0019] S102, the MCU circuit determines whether the vehicle terminal meets the sleep condition, if yes, execute S103, otherwise, execute S106;

[0020] S103, the MCU circuit controls the first output terminal to output a low level, and controls the vehicle-mounted terminal to sleep;

[0021] S104, the MCU circuit determines whether the vehicle terminal meets the wake-up condition, if yes, returns to S101, otherwise, executes S105;

[0022] S105, determining whether the backup battery voltage is lower than the threshold of the battery voltage detection circuit, if so, the OR gate circuit outputs a low level and turns off the backup battery power supply, otherwise, returning to S104;

[0023] S106, the MCU circuit detects the output voltage of the resistor voltage divider circuit, and determines whether the output voltage is continuously lower than a preset value within a preset time. If not, return to S102, otherwise, execute S107;

[0024] S107, the MCU circuit controls the first output terminal and the second output terminal to output a low level, and the OR gate circuit outputs a low level, turning off the backup battery power supply.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a backup battery undervoltage management circuit and method. When the vehicle-mounted terminal is fully functional, the backup battery is managed by software detection, which can effectively filter out voltage fluctuations caused by load fluctuations. In sleep mode, the battery voltage detection circuit is used to control the switch of the backup battery, effectively reducing standby power consumption, and the load power consumption in sleep mode is basically non-volatile, which will not cause misjudgment.

[0027] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention so that it can be implemented in accordance with the contents of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below.

[0028] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural block diagram of a backup battery undervoltage management circuit of the present invention;

[0030] Figure 2 A circuit diagram of a backup battery undervoltage management circuit of the present invention;

[0031] Figure 3 The present invention is a flowchart of a backup battery undervoltage management method. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] See also Figure 1 and Figure 2 As shown, a backup battery undervoltage management circuit of the present invention includes: an MCU circuit 10, an OR gate circuit 20, a battery voltage detection circuit 30, a resistor voltage divider circuit 40 and a switch circuit 50;

[0034] The MCU circuit 10 includes a first output terminal GPIO1 and a second output terminal GPIO2; the MCU circuit 10 sets the first output terminal GPIO1 and the second output terminal GPIO2 to a high or low level according to the working state of the vehicle terminal and / or the detected backup battery power;

[0035] The OR gate circuit 20 comprises a first input terminal, a second input terminal and an output terminal; the first input terminal of the OR gate circuit 20 is connected to the first output terminal GPIO1 of the MCU circuit 10; the second input terminal of the OR gate circuit 20 is connected to the voltage detection output terminal of the battery voltage detection circuit 30; the output terminal of the OR gate circuit 20 is connected to the switch circuit 50;

[0036] The battery voltage detection circuit 30 has a down-threshold input terminal connected to the backup battery; a power input terminal connected to the second output terminal GPIO2 of the MCU circuit 10; and a voltage detection output terminal connected to the second input terminal of the OR gate circuit 20;

[0037] The resistor voltage divider circuit 40 is arranged between the backup battery and the MCU circuit 10. When the vehicle terminal is not in a dormant state, the MCU circuit 10 detects the output of the resistor voltage divider circuit 40;

[0038] The switch circuit 50 is arranged between the OR gate circuit 20 and the backup battery, and controls whether to supply power to the MCU through the OR gate circuit 20.

[0039] The present invention provides a backup battery undervoltage management circuit, which combines the advantages of software detection of battery power and hardware battery voltage detection circuit detection. Since the power consumption of the battery voltage detection circuit is extremely low, it is powered directly through the second output terminal GPIO2 of the MCU circuit. When the MCU circuit works normally, the first output terminal GPIO1 and the second output terminal GPIO2 are turned on, and the backup battery power is detected by software. Due to the existence of the OR gate circuit, the first output terminal GPIO1 leads the backup battery to turn on. When the backup battery is undervoltage, the first output terminal GPIO1 and the second output terminal GPIO2 are turned off at the same time, which can effectively filter out voltage fluctuations caused by load fluctuations. In sleep mode, the first output terminal GPIO1 is turned off, the second output terminal GPIO2 is kept turned on, and the battery voltage detection circuit is used to control the switch of the backup battery, which can effectively reduce standby power consumption and reduce the difficulty of software development. In sleep mode, the load power consumption is basically not fluctuated, and no misjudgment will be caused.

[0040] Specifically, when the main power supply is working normally, the car battery provides a DC-DC power supply for the vehicle terminal, and the DC-DC power supply provides power for the MCU circuit through a low voltage difference linear regulator LDO. When the main power supply is turned off, the backup battery is started to supply power. When the backup battery is not under-voltage, the second output terminal GPIO2 is in a continuously open state, and the first output terminal GPIO1 is turned on during normal operation and turned off during sleep. When the backup battery is under-voltage, if it is in a normal working state, the first output terminal GPIO1 and the second output terminal GPIO2 are turned off at the same time. If it is in a sleep state, the battery voltage detection circuit will automatically turn off the battery without the need for software operation.

[0041] Through this control logic, the control process can be simplified and the amount of software development can be reduced.

[0042] Further, the OR gate circuit 20 includes a first diode D1 and a second diode D2; the anode of the first diode D1 is connected to the first output terminal GPIO1 of the MCU circuit 10, and the anode of the second diode D2 is connected to the voltage detection output terminal LDO of the battery voltage detection circuit 30; the cathode of the first diode D1 and the cathode of the second diode D2 are both connected to the switch circuit 50. When any one of the first output terminal GPIO1 of the MCU circuit 10 and the voltage detection output terminal LDO of the battery voltage detection circuit 30 outputs a high level, the backup battery is turned on.

[0043] The battery voltage detection circuit 30 includes a battery voltage detection chip U1; the down threshold input terminal FTH of the battery voltage detection chip U1 is connected to the backup battery battary through the second resistor R2, and its power input terminal VCC is connected to the second output terminal GPIO2 of the MCU circuit 10; its voltage detection output terminal LDO is connected to the second input terminal of the OR gate circuit 20.

[0044] The battery voltage detection circuit 30 also includes a filter circuit; the filter circuit is connected to the backup battery battary through a second resistor R2 and a third resistor R3; the filter circuit includes a fourth resistor R4 and a first capacitor C1 connected in parallel. Specifically, the shutdown voltage of the backup battery is set by the second resistor R2, the third resistor R3 and the fourth resistor R4, and the first capacitor C1 is used for filtering.

[0045] The resistor voltage divider circuit 40 includes a fifth resistor R5, a sixth resistor R6 and a second capacitor C2; one end of the fifth resistor R5 is connected to the backup battery battary, and the other end is connected to one end of the sixth resistor R6, one end of the second capacitor C2 and the input end ADC of the MCU circuit 10 respectively; the sixth resistor R6 and the second capacitor C2 are connected in parallel. The fifth resistor R5 and the sixth resistor R6 are used for resistor voltage division, and the second capacitor C2 is used for filtering.

[0046] The switch circuit 50 includes a transistor Q1; the base of the transistor Q1 is connected to the output end of the OR gate circuit 20; the emitter of the transistor Q1 is grounded; the collector of the transistor Q1 is connected to the backup battery through a first resistor R1. When the base of the transistor Q1 is at a high level, the backup battery is turned on; when the base of the transistor Q1 is at a low level, the backup battery is turned off.

[0047] The switch circuit 50 further includes a MOS transistor Q2; the gate of the MOS transistor Q2 is connected to the collector of the transistor Q1; the source of the MOS transistor Q2 is connected to the backup battery battary; the drain of the MOS transistor Q2 is connected to the MCU circuit 10 through a third diode D3. The MOS transistor Q2 is a power supply channel in the switch circuit. When the MOS transistor Q2 is turned on, the backup battery supplies power to the MCU circuit 10. The transistor Q1 is used to control the conduction of the MOS transistor Q2.

[0048] On the other hand, see Figure 3 As shown, the present invention provides a backup battery undervoltage management method, based on the backup battery undervoltage management circuit, comprising:

[0049] S101, the vehicle terminal starts the backup battery to supply power, and the MCU circuit 10 controls the first output terminal GPIO1 and the second output terminal GPIO2 to output a high level;

[0050] S102, the MCU circuit 10 determines whether the vehicle terminal meets the sleep condition, if yes, executes S103, otherwise, executes S106;

[0051] S103, the MCU circuit 10 controls the first output terminal GPIO1 to output a low level, and controls the vehicle terminal to sleep;

[0052] S104, the MCU circuit 10 determines whether the vehicle terminal meets the wake-up condition, if yes, returns to S101, otherwise, executes S105;

[0053] S105, determining whether the backup battery voltage is lower than the threshold of the battery voltage detection circuit 30, if yes, the OR gate circuit 20 outputs a low level and turns off the backup battery power supply, otherwise, returns to S104;

[0054] S106, the MCU circuit 10 detects the output voltage of the resistor voltage divider circuit 40, and determines whether the output voltage is continuously lower than a preset value within a preset time. If not, return to S102, otherwise, execute S107;

[0055] S107, the MCU circuit 10 controls the first output terminal GPIO1 and the second output terminal GPIO2 to output a low level, and the OR gate circuit 20 outputs a low level to turn off the backup battery power supply.

[0056] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A backup battery undervoltage management circuit, characterized in that: include: MCU circuit, OR gate circuit, battery voltage detection circuit, resistor voltage divider circuit and switch circuit; The MCU circuit comprises a first output terminal and a second output terminal; The MCU circuit sets the first output terminal and the second output terminal to high or low levels according to the working state of the vehicle-mounted terminal and / or the detected backup battery power; The OR gate circuit comprises a first input terminal, a second input terminal and an output terminal; the first input terminal of the OR gate circuit is connected to the first output terminal of the MCU circuit; the second input terminal of the OR gate circuit is connected to the voltage detection output terminal of the battery voltage detection circuit; the output terminal of the OR gate circuit is connected to the switch circuit; The battery voltage detection circuit has a down-threshold input terminal connected to the backup battery; a power input terminal connected to the second output terminal of the MCU circuit; and a voltage detection output terminal connected to the second input terminal of the OR gate circuit; The resistor voltage divider circuit is arranged between the backup battery and the MCU circuit, and when the vehicle-mounted terminal is not in a dormant state, the MCU circuit detects the output of the resistor voltage divider circuit; The switch circuit is arranged between the OR gate circuit and the backup battery, and controls whether to supply power to the MCU through the OR gate circuit; The OR gate circuit includes a first diode and a second diode; the anode of the first diode is connected to the MCU circuit, and the anode of the second diode is connected to the battery voltage detection circuit; the cathode of the first diode and the cathode of the second diode are both connected to the switch circuit; The battery voltage detection circuit includes a battery voltage detection chip; the down threshold input terminal of the battery voltage detection chip is connected to the backup battery through a second resistor, and the power input terminal is connected to the second output terminal of the MCU circuit; and the voltage detection output terminal is connected to the second input terminal of the OR gate circuit.

2. The backup battery undervoltage management circuit according to claim 1, characterized in that: The battery voltage detection circuit includes a filter circuit; the filter circuit is connected to the backup battery through a second resistor and a third resistor; the filter circuit includes a fourth resistor and a first capacitor connected in parallel.

3. The backup battery undervoltage management circuit according to claim 1, characterized in that: The resistor divider circuit includes a fifth resistor, a sixth resistor and a second capacitor; one end of the fifth resistor is connected to the backup battery, and the other end is respectively connected to one end of the sixth resistor, one end of the second capacitor and the input end of the MCU circuit; the sixth resistor and the second capacitor are connected in parallel.

4. The backup battery undervoltage management circuit according to claim 1, characterized in that: The switch circuit comprises a transistor; the base of the transistor is connected to the output end of the OR gate circuit; the emitter of the transistor is grounded; and the collector of the transistor is connected to the backup battery via a first resistor.

5. The backup battery undervoltage management circuit according to claim 4, characterized in that: The switch circuit also includes a MOS tube; the gate of the MOS tube is connected to the collector of the triode; the source of the MOS tube is connected to the backup battery; and the drain of the MOS tube is connected to the MCU circuit.

6. A backup battery undervoltage management method, characterized in that: A claim based on any one of claims 1 to 5, comprising: S101, the vehicle terminal starts the backup battery to supply power, and the MCU circuit controls the first output terminal and the second output terminal to output a high level; S102, the MCU circuit determines whether the vehicle terminal meets the sleep condition, if yes, execute S103, otherwise, execute S106; S103, the MCU circuit controls the first output terminal to output a low level, and controls the vehicle-mounted terminal to sleep; S104, the MCU circuit determines whether the vehicle terminal meets the wake-up condition, if yes, returns to S101, otherwise, executes S105; S105, determining whether the backup battery voltage is lower than the threshold of the battery voltage detection circuit, if so, the OR gate circuit outputs a low level and turns off the backup battery power supply, otherwise, returning to S104; S106, the MCU circuit detects the output voltage of the resistor voltage divider circuit, and determines whether the output voltage is continuously lower than a preset value within a preset time. If not, return to S102, otherwise, execute S107; S107, the MCU circuit controls the first output terminal and the second output terminal to output a low level, and the OR gate circuit outputs a low level, turning off the backup battery power supply.

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