A battery discharge control circuit

Abstract

The present invention discloses a battery discharge control circuit, which includes a DC-DC circuit and a battery voltage detection control unit, wherein the DC-DC circuit includes a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a printed inductor L1 and an MP2307 chip, and the battery voltage detection control unit includes a capacitor C6, a capacitor C10, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R13, a resistor R14, a diode D1, a diode D2, a voltage reference chip TL431, a battery voltage recovery detection unit and a battery over-discharge detection unit. The battery voltage is sampled and compared with a set reference voltage after sampling to control the output and shutdown of the DC-DC circuit. The two-way comparison design allows the battery to work when it is charged from an undervoltage state to a certain voltage, thereby preventing the battery from being over-discharged and preventing the battery from working in an undervoltage state.

Description

Technical Field

[0001] The present invention relates to the field of circuit design, and in particular to a battery discharge control circuit. Background Art

[0002] With the rise of new energy, batteries are increasingly used in new energy. The service life of batteries has a great impact on the performance of new energy equipment. There are many battery discharge control circuits on the market. Many products simply prevent the battery from over-discharging. When the battery stops discharging, the battery voltage will rise, but the battery power is insufficient. In this case, many products will mistakenly think that the battery has power and continue to discharge the battery, causing damage to the battery. Summary of the invention

[0003] The purpose of the present invention is to solve the problem of the existing battery discharge control circuit that when the battery stops discharging, the battery voltage will rise, but the battery power is insufficient. In this case, many products will mistakenly believe that the battery has power and continue to discharge the battery, causing damage to the battery.

[0004] The technical solution adopted by the present invention is: a battery discharge control circuit, which includes a DC-DC circuit and a battery voltage detection control unit, wherein the DC-DC circuit includes a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a printed inductor L1 and an MP2307 chip, wherein one end of a circuit formed by connecting the resistor R1, the resistor R2 and the capacitor C2 in parallel is connected to the FB pin of the MP2307 chip and the other end is grounded, one end of a circuit formed by connecting the resistor R3 and the capacitor C3 in series is connected to the COMP pin of the MP2307 chip and the other end is grounded, and the capacitor C 4 is connected to the SS pin of the MP2307 chip through a line and the capacitor C4 is grounded, the printed inductor L1 is connected to the SW pin of the MP2307 chip through a line and is connected to the line where the resistor R1 is located through a line, the capacitor C5 is connected to the BS pin of the MP2307 chip through a line and is connected to the line where the printed inductor L1 is located through a line, the capacitor C1 is connected to the IN pin of the MP2307 chip through a line and the capacitor C1 is grounded, the resistor R1 is a variable resistor, the EN pin of the MP2307 chip is an enable terminal, and the battery voltage detection control unit is connected to the EN pin of the MP2307 chip;

[0005] The battery voltage detection control unit includes a capacitor C6, a capacitor C10, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R13, a resistor R14, a diode D1, a diode D2, a voltage reference chip TL431, a battery voltage recovery detection unit and a battery over-discharge detection unit. The battery voltage recovery detection unit includes a first voltage comparator LM2903, a capacitor C7, a capacitor C8, a resistor R9 and a resistor R10. The battery over-discharge detection unit includes a second voltage comparator LM2903, a capacitor C9, a capacitor C10, a resistor R11 and a resistor R12. The resistors R5 and R8 are connected to the voltage reference chip TL431 through a line, and the voltage reference chip TL431 is grounded. The capacitor C6 and the resistor R7 are connected in parallel and connected to the voltage reference chip TL431, and the capacitor C6 and the resistor R7 are connected to the ground line. The resistors R5, R6 and The resistor R8 is connected to the voltage reference chip TL431, the voltage reference chip TL431 is connected to the negative electrode of the first voltage comparator LM2903 and the negative electrode of the second voltage comparator LM2903, the resistor R8 and the resistor R13 are pull-up resistors, the resistor R14 is a pull-down resistor, the capacitor C8 and the resistor R10 are connected in parallel, the parallel circuit is grounded and connected to the positive electrode of the first voltage comparator LM2903, the resistor R9 is connected to the circuit connecting the capacitor C8 and the resistor R10 to the positive electrode of the first voltage comparator LM2903, the output end of the first voltage comparator LM2903 is connected to the diode D1 through a circuit, the resistor R8 is connected to the circuit connecting the output end of the first voltage comparator LM2903 and the diode D1 through a circuit, the capacitor C7 is connected in series with the first voltage comparator LM2903 and the capacitor C7 is grounded, and the first voltage comparator LM2903 is grounded;

[0006] The capacitor C9 and the resistor R12 are connected in parallel, and the parallel circuit is grounded and connected to the positive electrode of the second voltage comparator LM2903. The resistor R11 is connected to the circuit connecting the capacitor C9 and the resistor R12 with the positive electrode of the second voltage comparator LM2903. The diode D1 is connected to the EN pin of the MP2307 chip. The output end of the second voltage comparator LM2903, the resistor R13, the resistor R14 and the capacitor C10 are all connected to the circuit connecting the diode D1 and the EN pin of the MP2307 chip through a circuit. The diode D2 is connected in series with the resistor R13. The resistor R14 is connected in parallel with the capacitor C10 and then grounded.

[0007] As a further improvement of the present invention, the input voltage of the DC-DC circuit is 4.75V to 23VDC, and the output voltage is 0.925V to 20VDC.

[0008] The beneficial effects of the present invention are as follows: after adopting this structure, the battery voltage is sampled, and after sampling, it is compared with the set reference voltage to control the output and shutdown of the DC-DC circuit. The two-way comparison design allows the battery to work when it is charged from an undervoltage state to a certain voltage. On the one hand, it can prevent the battery from being over-discharged, and on the other hand, it can work when the battery is in an undervoltage state. The circuit output voltage is adjustable, and the battery over-discharge protection voltage value and the battery recovery working voltage value can be set manually. For different batteries and different equipment, they can be flexibly adjusted to achieve a better matching of the battery discharge control and more reliable protection of the battery. It prevents the battery from being permanently damaged due to over-discharge, and prevents the battery from supplying power to the load before it recovers to a normal state. It has a load short-circuit protection function, which protects both the battery and the equipment and extends the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic block diagram of the circuit of the present invention.

[0010] Figure 2 This is a DC-DC circuit diagram of the present invention.

[0011] Figure 3 It is a circuit diagram of the battery voltage detection control unit in the present invention.

[0012] As shown in the figure: 1. Battery, 2. DC-DC circuit, 3. Battery voltage detection control unit, 4. MP2307 chip, 5. Voltage reference chip TL431, 6. Battery voltage recovery detection unit, 7. Battery over-discharge detection unit, 8. First voltage comparator LM2903, 9. Second voltage comparator LM2903. DETAILED DESCRIPTION

[0013] The technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0014] As shown in the figure, a battery discharge control circuit includes a DC-DC circuit 2 and a battery voltage detection control unit 3. The DC-DC circuit includes a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a printed inductor L1 and an MP2307 chip 4. One end of the circuit formed by connecting the resistor R1, the resistor R2 and the capacitor C2 in parallel is connected to the FB pin of the MP2307 chip and the other end is grounded. One end of the circuit formed by connecting the resistor R3 and the capacitor C3 in series is connected to the COMP pin of the MP2307 chip and the other end is grounded. The capacitor C4 is connected in series. The circuit is connected to the SS pin of the MP2307 chip and the capacitor C4 is grounded, the printed inductor L1 is connected to the SW pin of the MP2307 chip through the circuit and is connected to the circuit where the resistor R1 is located through the circuit, the capacitor C5 is connected to the BS pin of the MP2307 chip through the circuit and is connected to the circuit where the printed inductor L1 is located through the circuit, the capacitor C1 is connected to the IN pin of the MP2307 chip through the circuit and the capacitor C1 is grounded, the resistor R1 is a variable resistor, the EN pin of the MP2307 chip is an enable terminal, and the battery voltage detection control unit is connected to the EN pin of the MP2307 chip;

[0015] The battery voltage detection control unit includes a capacitor C6, a capacitor C10, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R13, a resistor R14, a diode D1, a diode D2, a voltage reference chip TL431, a battery voltage recovery detection unit and a battery over-discharge detection unit. The battery voltage recovery detection unit includes a first voltage comparator LM2903, a capacitor C7, a capacitor C8, a resistor R9 and a resistor R10. The battery over-discharge detection unit includes a second voltage comparator LM2903, a capacitor C9, a capacitor C10, a resistor R11 and a resistor R12. The resistors R5 and R8 are connected to the voltage reference chip TL431 through a line, and the voltage reference chip TL431 is grounded. The capacitor C6 and the resistor R7 are connected in parallel and connected to the voltage reference chip TL431, and the capacitor C6 and the resistor R7 are connected to the ground line. The resistors R5, R6 and The resistor R8 is connected to the voltage reference chip TL431, the voltage reference chip TL431 is connected to the negative electrode of the first voltage comparator LM2903 and the negative electrode of the second voltage comparator LM2903, the resistor R8 and the resistor R13 are pull-up resistors, the resistor R14 is a pull-down resistor, the capacitor C8 and the resistor R10 are connected in parallel, the parallel circuit is grounded and connected to the positive electrode of the first voltage comparator LM2903, the resistor R9 is connected to the circuit connecting the capacitor C8 and the resistor R10 to the positive electrode of the first voltage comparator LM2903, the output end of the first voltage comparator LM2903 is connected to the diode D1 through a circuit, the resistor R8 is connected to the circuit connecting the output end of the first voltage comparator LM2903 and the diode D1 through a circuit, the capacitor C7 is connected in series with the first voltage comparator LM2903 and the capacitor C7 is grounded, and the first voltage comparator LM2903 is grounded;

[0016] The capacitor C9 and the resistor R12 are connected in parallel, and the parallel circuit is grounded and connected to the positive electrode of the second voltage comparator LM2903. The resistor R11 is connected to the circuit connecting the capacitor C9 and the resistor R12 with the positive electrode of the second voltage comparator LM2903. The diode D1 is connected to the EN pin of the MP2307 chip. The output end of the second voltage comparator LM2903, the resistor R13, the resistor R14 and the capacitor C10 are all connected to the circuit connecting the diode D1 and the EN pin of the MP2307 chip through a circuit. The diode D2 is connected in series with the resistor R13. The resistor R14 is connected in parallel with the capacitor C10 and then grounded.

[0017] The input voltage of the DC-DC circuit is 4.75V~23VDC, and the output voltage is 0.925V~20VDC.

[0018] In the present invention, the C-DC circuit controls the enable pin EN of the MP2307 chip separately, thereby controlling the on and off of the MP2307. The output voltage value of the DC-DC circuit of the present invention is adjustable, and the calculation formula is as follows:

[0019] .

[0020] The resistor R2 is 10kΩ with an accuracy of 1%, and the resistor R1 is an adjustable resistor. The commonly used voltage output values ​​correspond to the values ​​of the resistors R1 and R2 as shown in the table:

[0021] .

[0022] The DC-DC circuit of the present invention has a load short-circuit protection function. When the load is short-circuited, the current output by MP2307 increases instantly, MP2307 automatically performs over-current protection, and the DC-DC circuit stops outputting.

[0023] In the present invention, the reference voltage output by TL431 is connected to the negative electrode of the first voltage comparator LM2903 and the negative electrode of the second voltage comparator LM2903, and a two-way comparison design is adopted, one way is used to detect whether the battery voltage is lower than the battery over-discharge protection voltage value, and the other way is used to detect whether the battery voltage has recovered to a voltage value that can work normally. The battery recovery working voltage value is set by the value of resistor R9 and resistor R10, and the formula is as follows:

[0024] .

[0025] The values ​​of resistors R11 and R12 are used to set the battery over-discharge protection voltage value. The formula is as follows:

[0026] .

[0027] When the sampled battery voltage is lower than the battery over-discharge protection voltage value, the second voltage comparator LM2903 input positive electrode is lower than the input negative electrode reference voltage, the second voltage comparator LM2903 outputs a low level to turn off MP2307, the DC-DC circuit has no output, and the battery does not discharge; when the battery voltage recovers to a value higher than the battery recovery working voltage value, the first voltage comparator LM2903 input positive electrode is higher than the input negative electrode reference voltage, the first voltage comparator LM2903 outputs a high level to turn on MP2307, the DC-DC circuit has output, and the battery discharges normally. During the battery discharge process, when the battery voltage drops to between the battery recovery working voltage value and the battery over-discharge protection voltage value, the first voltage comparator LM2903 outputs a low level. Due to the effect of the diode D1, the low level output by the first voltage comparator is prevented from pulling down the EN terminal of the MP2307. The second voltage comparator LM2903 outputs a high level. Since the MP2307 is not turned off, the DC-DC circuit has an output, which is pulled up by the pull-up resistor R13 to keep the EN terminal outputting a stable high level. In this way, when the battery is discharged, when the voltage drops below the battery over-discharge protection voltage value, the DC-DC circuit is turned off; the battery is charged, and the voltage is restored to the battery over-discharge protection voltage value. When the discharge protection voltage value is between the battery recovery working voltage value, the first voltage comparator LM2903 outputs a low level and the second voltage comparator LM2903 outputs a high level. Since MP2307 is turned off, the DC-DC circuit has no output, and the pull-down resistor R14 pulls down. The high level output by the second voltage comparator LM2903 cannot drive the EN enable terminal to work normally. Only when the voltage recovers to above the battery recovery working voltage value, the first voltage comparator LM2903 outputs a high level, which is pulled up by the pull-up resistor R8 to provide energy to drive the EN enable terminal, so that MP2307 works normally, the DC-DC circuit has output, and the battery discharges normally.

[0028] Those skilled in the art should be aware that the protection scheme of the present invention is not limited to the above-mentioned embodiments, and various arrangements, combinations and transformations can be performed on the basis of the above-mentioned embodiments. Without violating the spirit of the present invention, various transformations of the present invention fall within the protection scope of the present invention.

Claims

1. A battery discharge control circuit, characterized in that: It comprises a DC-DC circuit (2) and a battery voltage detection control unit (3). The DC-DC circuit comprises a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a capacitor C5, a resistor R1, a resistor R2, a resistor R3, a printed inductor L1 and an MP2307 chip (4). One end of a circuit formed by connecting the resistor R1, the resistor R2 and the capacitor C2 in parallel is connected to the FB pin of the MP2307 chip and the other end is grounded. One end of a circuit formed by connecting the resistor R3 and the capacitor C3 in series is connected to the COMP pin of the MP2307 chip and the other end is grounded. The capacitor C4 is connected to the MP2307 chip via a circuit. The SS pin of the MP2307 chip is connected and the capacitor C4 is grounded, the printed inductor L1 is connected to the SW pin of the MP2307 chip through a line and is connected to the line where the resistor R1 is located through a line, the capacitor C5 is connected to the BS pin of the MP2307 chip through a line and is connected to the line where the printed inductor L1 is located through a line, the capacitor C1 is connected to the IN pin of the MP2307 chip through a line and the capacitor C1 is grounded, the resistor R1 is a variable resistor, the EN pin of the MP2307 chip is an enable terminal, and the battery voltage detection control unit is connected to the EN pin of the MP2307 chip; The battery voltage detection control unit comprises a voltage reference chip TL431 (5), a battery voltage recovery detection unit (6) and a battery over-discharge detection unit (7); pin 1 of the voltage reference chip TL431 is connected to pin 2 of a first voltage comparator LM2903 and pin 6 of a second voltage comparator LM2903 in sequence; pin 2 of the voltage reference chip TL431 is grounded, and a capacitor C6 and a resistor R7 are connected in parallel between pin 1 and pin 2 of the voltage reference chip TL431; pin 3 of the voltage reference chip TL431 is connected to resistors R5, R6 and R8, the other end of the resistor R5 is connected to a power supply VB, the other end of the resistor R6 is connected to pin 2 of the voltage reference chip TL431, and the other end of the resistor R8 is connected to the EN pin of the MP2307 chip via a diode D1; The battery voltage recovery detection unit comprises a first voltage comparator LM2903 (8), wherein pin 1 of the first voltage comparator LM2903 is connected to the EN pin of the MP2307 chip via a diode D1; pin 3 of the first voltage comparator LM2903 is respectively connected to a resistor R9, a capacitor C8 and a resistor R10 connected in parallel, the other end of the resistor R9 is connected to a power supply VB, and the other ends of the capacitor C8 and the resistor R10 connected in parallel are grounded; pin 4 of the first voltage comparator LM2903 is grounded; pin 8 of the first voltage comparator is respectively connected to the power supply VB and a capacitor C7, and the other end of the capacitor C7 is grounded; The battery over-discharge detection unit comprises a second voltage comparator LM2903 (9), wherein pin 7 of the second voltage comparator LM2903 is connected to the EN pin of the MP2307 chip; pin 5 of the second voltage comparator is respectively connected to a resistor R11, a capacitor C9 and a resistor R12 connected in parallel, the other end of the resistor R11 is connected to a power supply VB, and the other ends of the capacitor C9 and the resistor R12 connected in parallel are grounded; The EN pin of the MP2307 chip is also connected to a resistor R13, a capacitor C10 and a resistor R14 in parallel, the other end of the resistor R13 is connected to a 3.3V voltage through a diode D2, and the other ends of the capacitor C10 and the resistor R14 in parallel are grounded.

2. A battery discharge control circuit according to claim 1, characterized in that: The input voltage of the DC-DC circuit is 4.75V~23VDC, and the output voltage is 0.925V~20VDC.

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