Vehicle-mounted low-cost storage battery high and low voltage detection circuit

Abstract

The utility model discloses a vehicle-mounted low-cost storage battery high and low voltage detection circuit, which comprises a battery input end, a detection interruption output end, a high voltage detection judgment circuit, a low voltage detection judgment circuit and a level conversion circuit. According to the utility model, when the voltage of the storage battery is in a normal working range, a low level is output to the MCU; and when the voltage of the storage battery exceeds a normal working range, a high level is output to the MCU, so that the problems that AD sampling always occupies MCU resources to influence the running speed of the system and the real-time performance is low are solved, and the circuit cost is greatly reduced.

Description

Technical Field

[0001] The utility model relates to a detection circuit, in particular to a vehicle-mounted low-cost high and low voltage detection circuit for a storage battery. Background Art

[0002] An automotive storage battery is responsible for starting the engine, powering vehicle-mounted electrical equipment, etc.; at the same time, when the storage battery is under-voltage, the generator will charge the storage battery. Therefore, the automotive storage battery is in a relatively complex electrical environment. When the engine starts, due to a very large starting current, the battery voltage will be instantaneously pulled down to 6V or even below 6V; when the engine is not started, if too many electrical equipment are turned on for a long time, it will also cause the battery voltage to be too low and under-voltage. At the same time, when motors such as window lifters and seat movers work, a lot of spike pulse voltages will be superimposed on the voltage of the storage battery, thus exceeding 18V; and when the current of the electrical equipment is suddenly interrupted, due to the existence of inductance components such as wiring harnesses, the storage battery will have a transient over-voltage.

[0003] Therefore, when the storage battery is under-voltage, over-discharge needs to be prevented to avoid shortening or even damaging the service life of the storage battery; at the same time, when the voltage is too low, many electronic components inside the electrical equipment cannot work properly. When the storage battery is over-voltage, the electrical equipment needs to prevent the high voltage from damaging the inside of the equipment. In a vehicle-mounted system, it is generally required that electrical equipment such as a multimedia navigation system ensure normal operation within a voltage range of 9 - 18V; outside this range, its functions may not be realized, but it cannot be damaged and cannot affect other equipment in the vehicle-mounted system. To meet this requirement, electrical equipment in the vehicle-mounted system generally needs to add a circuit for real-time detection of the storage battery voltage range to achieve the power management of the system.

[0004] Currently, in vehicle-mounted systems, there are two main mainstream solutions for the storage battery voltage detection circuit: one is to use a dedicated comparator chip, which will actively send an interrupt signal to the MCU when the voltage exceeds the working range, and the MCU will perform power management on the system after receiving the signal. This solution has high detection real-time performance, a simple circuit, and very low static current itself, and will not cause additional discharge to the battery, but the cost is relatively high; the other solution is to divide the voltage of the storage battery with a resistor and then connect it to the AD port of the MCU. The MCU samples the voltage value in real time, and when the voltage exceeds the working range, it performs power management on the system. This solution has a lower cost, but it requires the MCU to continuously sample the voltage of the AD port, always occupying MCU resources, affecting the system operation speed, and the real-time performance of AD sampling is relatively low. Summary of the Utility Model

[0005] The purpose of the utility model is to overcome the defects of the prior art, provide a vehicle-mounted low-cost high and low voltage detection circuit for a storage battery, solve the problems that AD sampling always occupies MCU resources and affects the system operation speed, and has low real-time performance, and greatly reduces the circuit cost.

[0006] The purpose of the present utility model is achieved as follows: A vehicle-mounted low-cost battery high and low voltage detection circuit includes a battery input terminal and a detection interrupt output terminal, and further includes a high voltage detection and judgment circuit, a low voltage detection and judgment circuit, and a level conversion circuit;

[0007] The high voltage detection circuit includes a triode Q1, a resistor R1, a resistor R2, and a voltage stabilizing diode ZD1; the battery input terminal is electrically connected to the emitter of the triode Q1 and one end of the resistor R2, and the base of the triode Q1 is electrically connected to one end of the resistor R1; the other end of the resistor R1 is electrically connected to the resistor R2 and the negative electrode of the voltage stabilizing diode ZD1, and the positive electrode of the voltage stabilizing diode ZD1 is grounded;

[0008] The low voltage detection and judgment circuit includes a resistor R5, a resistor R6, and a triode Q2. The battery input terminal is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the resistor R5 and the base of the triode Q2; one end of the resistor R5 is also electrically connected to the emitter of the triode Q2 and grounded;

[0009] The level conversion circuit includes a resistor R7, a resistor R8, a resistor R9, and a triode Q3. The battery input terminal is electrically connected to one end of the resistor R7 through a triode Q4, and the other end of the resistor R7 is electrically connected to one end of the resistor R8 and the base of the triode Q3; the emitter of the triode Q3 is grounded with the other end of the resistor R8; the collector of the triode Q3 is electrically connected to one end of the resistor R9, and the other end of the resistor R9 is electrically connected to the power supply VDD of the MCU; the detection interrupt output terminal is electrically connected to the MCU.

[0010] The present utility model adopts the above technical solutions. Compared with the prior art, the beneficial effects are as follows: By using discrete devices, the cost of the solution is greatly reduced; at the same time, it is not necessary to continuously sample using the AD port of the MCU, which will not occupy the MCU resources. When the battery voltage is within the normal working range, a low level will be output to the MCU; when the battery voltage exceeds the normal working range, a high level will be output to the MCU, which will not affect the system operation speed either. Moreover, this solution uses interrupt detection, with high real-time performance.

[0011] Further, the triode Q1 is also connected in parallel with a resistor R3, and the collector of the triode Q1 is electrically connected to the base of the triode Q4.

[0012] Further, a capacitor C1 is also connected in parallel on the resistor R5.

[0013] Further, the collector of the triode Q2 is electrically connected to the base of the triode Q4 through a resistor R4.

[0014] Further, the emitter of the triode Q4 is electrically connected to the battery input terminal, and the collector of the triode Q4 is electrically connected to the resistor R7.

[0015] Further, a capacitor C2 is connected in parallel to the resistor R8.

[0016] Further, the triodes Q1 and Q4 are PNP triodes.

[0017] Further, the triodes Q2 and Q3 are NPN triodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Block diagram of the present utility model.

[0019] Figure 2 Schematic circuit diagram of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] As Figure 1 shown, after passing through the high and low voltage detection circuit, the automotive battery outputs high and low levels to the MCU, and the MCU determines whether it is within the normal working range, thereby realizing the power management of the system. The high and low voltage detection circuit includes a high voltage detection and judgment circuit, a low voltage detection and judgment circuit, and a level conversion circuit; when the battery voltage is higher than the high voltage set value (such as 18V), after high voltage detection and judgment, no voltage is output to the subsequent stage; when the battery voltage is lower than the low voltage set value (such as 9V), after low voltage detection and judgment, no voltage is output to the subsequent stage; when the battery voltage is within the normal working range (such as 9 - 18V), after high voltage detection and judgment and low voltage detection and judgment, voltage is output to the subsequent stage; the level conversion circuit is used to convert the battery voltage into a voltage that meets the level requirements of the MCU input interface.

[0021] As Figure 2 shown, a vehicle-mounted low-cost battery high and low voltage detection circuit includes a battery input terminal and a detection interrupt output terminal, and further includes a high voltage detection and judgment circuit, a low voltage detection and judgment circuit, and a level conversion circuit;

[0022] The high voltage detection circuit includes a triode Q1, resistors R1 and R2, and a voltage stabilizing diode ZD1; the battery input terminal is electrically connected to the emitter of the triode Q1 and one end of the resistor R2, and the base of the triode Q1 is electrically connected to one end of the resistor R1; the other end of the resistor R1 is electrically connected to the other end of the resistor R2 and the negative electrode of the voltage stabilizing diode ZD1, and the positive electrode of the voltage stabilizing diode ZD1 is grounded; the triode Q1 is also connected in parallel with the resistor R3, and the collector of the triode Q1 is electrically connected to the base of the triode Q4;

[0023] The low-voltage detection and judgment circuit includes resistor R5, resistor R6, and triode Q2. The battery input terminal is electrically connected to one end of resistor R6, and the other end of resistor R6 is electrically connected to resistor R5 and the base of triode Q2; one end of resistor R5 is also electrically connected to the emitter of triode Q2 and grounded; a capacitor C1 is also connected in parallel across resistor R5; the collector of triode Q2 is electrically connected to the base of triode Q4 through resistor R4; the emitter of triode Q4 is electrically connected to the battery input terminal, and the collector of triode Q4 is electrically connected to resistor R7;

[0024] The level conversion circuit includes resistor R7, resistor R8, resistor R9, and triode Q3. The battery input terminal is electrically connected to one end of resistor R7 through triode Q4, and the other end of resistor R7 is electrically connected to one end of resistor R8 and the base of triode Q3; the emitter of triode Q3 is grounded to the other end of resistor R8; a capacitor C2 is connected in parallel across resistor R8; the collector of triode Q3 is electrically connected to one end of resistor R9, and the other end of resistor R9 is electrically connected to the power supply VDD of the MCU; the detection interrupt output terminal is electrically connected to the MCU; triodes Q1 and Q4 are PNP triodes; triodes Q2 and Q3 are NPN triodes.

[0025] When the present utility model works, the high-voltage detection and judgment threshold value: is mainly determined by triode Q1, resistors R1 and R2, and zener diode ZD1. The high-voltage detection and judgment threshold value is the zener voltage value of zener diode ZD1 plus the V BE voltage value;

[0026] The low-voltage detection and judgment threshold value: is mainly determined by resistors R5 and R6, and triode Q2. The low-voltage detection and judgment threshold value is V BE *(R5 + R6) / R5;

[0027] When the battery voltage is lower than the low-voltage detection and judgment threshold value, after the battery voltage B+ is divided by resistors R5 and R6, it is lower than the conduction voltage V of triode Q2 BE , that is, it is in the cut-off state; the zener diode ZD1 is in the reverse cut-off region, the voltage at point A is equal to the battery voltage B+, and triode Q1 is in the cut-off state; the voltage at point B is approximately equal to the battery voltage B+, so triode Q4 is in the cut-off state; the voltage at point C is 0V, and triode Q3 is in the cut-off state. Therefore, B+_DET_MCU outputs a high level to the MCU;

[0028] At this time, the static current of the entire high- and low-voltage detection circuit system is approximately equal to the battery voltage (B+) / (R5 + R6).

[0029] When the battery voltage is higher than the high-voltage detection and judgment threshold value, after the battery voltage B+ is divided by resistors R5 and R6, it is higher than the conduction voltage V of triode Q2 BE, that is, it is in the conducting state; the zener diode ZD1 is in the reverse breakdown region, the voltage at point A is the zener voltage of ZD1 (reverse breakdown voltage value), and the triode Q1 is in the conducting state; the voltage at point B is equal to the battery voltage (B+) - the V CE voltage value of the triode Q1, so the triode Q4 is in the cut-off state; the voltage at point C is 0V, and the triode Q3 is in the cut-off state. Therefore, B+_DET_MCU outputs a high level to the MCU;

[0030] At this time, the static current of the entire high and low voltage detection circuit system is approximately equal to (battery voltage (B+) - zener voltage of zener diode ZD1) / R2 + (battery voltage (B+) - zener voltage of zener diode ZD1 - conduction voltage V of triode Q1 BE ) / R1 + (battery voltage (B+) - V of triode Q1 CE voltage value - V of triode Q2 CE voltage value) / R4 + (battery voltage (B+) - conduction voltage V of triode Q2 BE ).

[0031] When the battery voltage is within the normal operating range, after the battery voltage B+ is divided by resistors R5 and R6, it is higher than the conduction voltage V of triode Q2 BE , that is, it is in the conducting state; the zener diode ZD1 is in the reverse cut-off region, the voltage at point A is equal to the battery voltage B+, and the triode Q1 is in the cut-off state; after the battery voltage B+ is divided by resistors R3 and R4, the voltage across resistor R3 is higher than the conduction voltage V of triode Q4 BE , that is, it is in the conducting state; the voltage at point C is the battery voltage (B+) - the V CE voltage value of triode Q4, and after being divided by resistors R7 and R8, it is higher than the conduction voltage V of triode Q3 BE , that is, it is in the conducting state. Therefore, B+_DET_MCU outputs a low level to the MCU;

[0032] At this time, the static current of the entire high and low voltage detection circuit system is approximately equal to (battery voltage (B+) - conduction voltage V of triode Q2 BE ) / R6 + (battery voltage (B+) - conduction voltage V of triode Q4 BE - V of triode Q2 CE voltage value) / R4 + (battery voltage (B+) - V of triode Q4 CE voltage value - conduction voltage V of triode Q3 BE ).

[0033] The utility model provides a vehicle-mounted low-cost battery high-low voltage detection circuit. When the battery voltage is within the normal working range, a low level is output to the MCU; when the battery voltage exceeds the normal working range, a high level is output to the MCU.

[0034] The utility model is not limited to the above embodiments. Based on the technical solutions disclosed in the utility model, those skilled in the art can make some substitutions and deformations to some technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the utility model.

Claims

1. A low-cost vehicle-mounted battery high and low voltage detection circuit, including a battery input end and a detection interruption output end, characterized in that, It also includes a high-voltage detection and judgment circuit, a low-voltage detection and judgment circuit, and a level conversion circuit; The high-voltage detection and judgment circuit includes a triode Q1, resistors R1 and R2, and a voltage regulator diode ZD1; the battery input terminal is electrically connected to the emitter of the triode Q1 and one end of the resistor R2, and the base of the triode Q1 is electrically connected to one end of the resistor R1; the other end of the resistor R1 is electrically connected to the resistor R2 and the negative electrode of the voltage regulator diode ZD1, and the positive electrode of the voltage regulator diode ZD1 is grounded; The low-voltage detection and judgment circuit includes resistors R5 and R6 and a triode Q2. The battery input terminal is electrically connected to one end of the resistor R6, and the other end of the resistor R6 is electrically connected to the resistor R5 and the base of the triode Q2; one end of the resistor R5 is also electrically connected to the emitter of the triode Q2 and grounded; The level conversion circuit includes resistors R7, R8, R9 and a triode Q3. The battery input terminal is electrically connected to one end of the resistor R7 through the triode Q4. The other end of the resistor R7 is electrically connected to one end of the resistor R8 and the base of the triode Q3; the emitter of the triode Q3 is grounded with the other end of the resistor R8; the collector of the triode Q3 is electrically connected to one end of the resistor R9, and the other end of the resistor R9 is electrically connected to the power supply VDD of the MCU; the detection interrupt output terminal is electrically connected to the MCU.

2. The vehicle-mounted low-cost battery high and low voltage detection circuit according to claim 1, characterized in that, The triode Q1 is also connected in parallel with the resistor R3, and the collector of the triode Q1 is electrically connected to the base of the triode Q4.

3. The vehicle-mounted low-cost battery high and low voltage detection circuit according to claim 1, characterized in that, A capacitor C1 is also connected in parallel with the resistor R5.

4. The low-cost vehicle-mounted high-low voltage detection circuit for storage batteries according to claim 1, wherein The collector of the triode Q2 is electrically connected to the base of the triode Q4 through the resistor R4.

5. The vehicle-mounted low-cost battery high and low voltage detection circuit according to claim 1, characterized in that, The emitter of the triode Q4 is electrically connected to the battery input terminal, and the collector of the triode Q4 is electrically connected to the resistor R7.

6. The vehicle-mounted low-cost battery high and low voltage detection circuit according to claim 1, characterized in that, A capacitor C2 is connected in parallel with the resistor R8.

7. A low-cost vehicle-mounted battery high and low voltage detection circuit according to claim 1, characterized in that, The triodes Q1 and Q4 are PNP triodes.

8. A low-cost vehicle-mounted battery high and low voltage detection circuit according to claim 1, characterized in that, The triodes Q2 and Q3 are NPN triodes.

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