Protection circuit for preventing excessive power

Abstract

The utility model provides a protection circuit for preventing overlarge power, which comprises a voltage detection circuit and a current regulation circuit, and is characterized in that the voltage detection circuit comprises a first protection resistor, a second protection resistor, a third divider resistor, a fourth divider resistor, an NMOS (N-channel Metal Oxide Semiconductor) tube and a voltage-regulator tube, the current adjusting circuit comprises a first capacitor, a fifth divider resistor and a sixth divider resistor, and the protection circuit can adjust and change the charging current according to different charging voltages, so that the power is ensured to be within a safe range, the power is prevented from being too large, and the situation that charging equipment is damaged and potential safety hazards are caused due to certain power is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery protection circuits, in particular to a protection circuit for preventing excessive power. Background Art

[0002] With the development of electronic technology, the use of lithium batteries is becoming more and more common, and the supporting charging equipment is also becoming more and more popular. The most common type-C interface currently outputs 5V or 12V voltage according to different PD protocols. Under the same charging current conditions, the larger the input voltage, the greater the corresponding power. If the power is constant and the charging current is not changed, the charger will be damaged when a high voltage is used, causing safety problems. Therefore, it is of great application value to design a circuit that can flexibly adjust the charging current according to the charging voltage when the power is constant. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a protection circuit for preventing excessive power.

[0004] In order to solve the above technical problems, the technical solution of the utility model is:

[0005] A protection circuit for preventing excessive power is composed of a voltage detection circuit and a current adjustment circuit, wherein:

[0006] The voltage detection circuit includes a first protection resistor, a second protection resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor, an NMOS tube and a voltage-stabilizing tube, VCC is electrically connected to the first protection resistor, another pin of the first protection resistor is electrically connected to the drain of the NMOS tube, and is also electrically connected to the input end of the single-chip computer, so as to detect whether the NMOS tube is turned on, the gate of the NMOS tube is electrically connected to the second protection resistor, VBUS is connected to the negative electrode of the voltage-stabilizing tube, the anode of the voltage-stabilizing tube is electrically connected to the third voltage-dividing resistor and the fourth voltage-dividing resistor, and the other end of the third voltage-dividing resistor is electrically connected to the gate of the NMOS tube;

[0007] The current regulating circuit includes a first capacitor, a fifth voltage-dividing resistor and a sixth voltage-dividing resistor. The single chip is electrically connected to the first capacitor and is electrically connected to the charge-discharge chip through the fifth voltage-dividing resistor and the sixth voltage-dividing resistor.

[0008] Preferably, in the above-mentioned protection circuit for preventing over-power, the VCC is a 5V power supply voltage.

[0009] Preferably, in the above-mentioned protection circuit for preventing excessive power, the NMOS tube is an N-channel field effect tube.

[0010] Preferably, in the above-mentioned protection circuit for preventing excessive power, the voltage regulator tube is a 5.6V voltage regulator tube.

[0011] Preferably, in the above-mentioned protection circuit for preventing excessive power, the first protection resistor is a thick film resistor.

[0012] Preferably, in the above-mentioned protection circuit for preventing excessive power, the second protection resistor is a thick film resistor.

[0013] Preferably, in the above-mentioned protection circuit for preventing excessive power, the third voltage-dividing resistor is a thick-film resistor.

[0014] Preferably, in the above-mentioned protection circuit for preventing excessive power, the fourth voltage-dividing resistor is a thick-film resistor.

[0015] Preferably, in the above-mentioned protection circuit for preventing excessive power, the fifth voltage-dividing resistor is a thick-film resistor.

[0016] Preferably, in the above-mentioned protection circuit for preventing excessive power, the sixth voltage-dividing resistor is a thick-film resistor.

[0017] Preferably, in the above-mentioned protection circuit for preventing over-power, the single-chip microcomputer model is FM33LC023U.

[0018] Preferably, in the above-mentioned protection circuit for preventing excessive power, the charging and discharging chip model is BQ24610.

[0019] Beneficial effects:

[0020] The over-power protection circuit can adjust and change the charging current according to the different charging voltages, thereby ensuring that the power is within a safe range, preventing excessive power, and avoiding damage to the charging equipment due to power shortages, thereby causing safety hazards. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a circuit diagram of the protection circuit for preventing overpower as described in Example 1.

[0022] Figure 2 This is the electrical block diagram of the protection circuit for preventing overpower as described in Example 1. DETAILED DESCRIPTION

[0023] A protection circuit for preventing overpower of the utility model is described in detail below in conjunction with the embodiments and drawings.

[0024] The NMOS tube Q15 used in the following embodiments is an N-channel field effect tube, the voltage regulator D14 is a 5.6V voltage regulator, the first protection resistor R80, the second protection resistor R81, the third voltage-dividing resistor D43, the fourth voltage-dividing resistor R65, the fifth voltage-dividing resistor R78 and the sixth voltage-dividing resistor R79 are all thick film resistors, the microcontroller model is the FM33LC023U chip, and the charge and discharge chip U5 model is the BQ24610 chip.

[0025] Example 1

[0026] like Figure 1 As shown, the protection circuit for preventing excessive power is composed of a voltage detection circuit and a current adjustment circuit, wherein:

[0027] The voltage detection circuit includes a first protection resistor R80, a second protection resistor R81, a third voltage-dividing resistor R43, a fourth voltage-dividing resistor R65, an NMOS tube Q15 and a voltage-stabilizing tube D14, VCC is connected to one pin of the first protection resistor R80, another pin of the first protection resistor R80 is connected to the drain of the NMOS tube Q15, and a signal VoCtr l is connected as an input terminal of a single-chip computer to detect whether the NMOS tube Q15 is turned on, wherein VCC is a 5V power supply voltage; the gate of the NMOS tube Q15 is connected to the ground by the second protection resistor R81, and the source of the NMOS tube Q15 is grounded. VBUS is connected to the negative electrode of the voltage-stabilizing tube D14, and the anode of the voltage-stabilizing tube D14 passes through the third voltage-dividing resistor R43 and the fourth voltage-dividing resistor R65, wherein the other end of the fourth voltage-dividing resistor R65 is grounded, and the other end of the third voltage-dividing resistor R43 is connected to the gate of the NMOS tube Q15. The voltage detection circuit uses the voltage of the VBUS signal (5V or 12V) after passing through the voltage regulator D14 as the voltage division of the third voltage-dividing resistor R43 and the fourth voltage-dividing resistor R65, and reversely obtains the voltage of the gate of the NMOS tube. When the VBUS signal is 5V power supply, the NMOS tube Q15 is not turned on, and the Vol Ctr l signal is a high level; when the VBUS signal is 12V power supply, the NMOS tube Q15 is turned on, and the Vol Ctr l signal is a high level. This level is used as a signal detected by the single-chip microcomputer to prepare for subsequent current processing.

[0028] The current adjustment circuit includes a first capacitor C46, ​​a fifth voltage-dividing resistor R78 and a sixth voltage-dividing resistor R79. The single-chip microcomputer outputs an I Ctr l signal through a DAC and filters it through the first capacitor C46. At the same time, the I Ctr l signal is divided by the fifth voltage-dividing resistor R78 and the sixth voltage-dividing resistor R79 and then given to the 11th pin of the charge-discharge chip U5. The current adjustment circuit is determined by the voltage of the 11th pin of the charge-discharge chip U5. The voltage is obtained by dividing the voltage of I Ctr l through the fifth voltage-dividing resistor R78 and the sixth voltage-dividing resistor R79. The charging current can be adjusted by changing the voltage of I Ctr l. When the voltage value of the I Ctr l signal changes, the voltage value of the 11th pin of U5 changes accordingly after being divided by the fifth voltage-dividing resistor R78 and the sixth voltage-dividing resistor R79, and different current values ​​are obtained.

[0029] The voltage detection circuit and current adjustment circuit in the above-mentioned protection circuit for preventing excessive power determine the current with which the charge-discharge chip U5 is charged, and the charging current is changed by detecting the input voltage (changing the charging current can be adjusted by software methods known in the art). VBUS is the input voltage, which can be 5V or 12V. After passing through the voltage regulator tube D14, the voltage divided by the resistor R43 and the resistor R65 is obtained, and then the voltage of the NMOS tube gate is obtained. According to the size of the gate voltage, the first NOMS tube Q15 is turned on or off, and the voltage of Vol Ctr l is obtained. This pin is connected to the I / O port of the single-chip microcomputer as the input of the high and low levels of the single-chip microcomputer. I Ctr l is connected to the I / O with DAC function of the single-chip microcomputer, and different voltages are output through the voltage divided by the fifth voltage-dividing resistor R78 and the sixth voltage-dividing resistor R79. The voltage after voltage division is connected to the 11 pin of the charge-discharge chip U5, and the charge-discharge chip U5 changes the corresponding current according to the voltage output of the 11 pin. The fifth voltage-dividing resistor R78 and the sixth voltage-dividing resistor R79 can be adjusted according to the reference value of the single-chip microcomputer ADC, so as to improve the accuracy of ADC acquisition and further improve the accuracy of the charging current.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are considered to be within the protection scope of the present invention.

Claims

1. A protection circuit to prevent overpower, characterized in that: It consists of a voltage detection circuit and a current adjustment circuit, among which: The voltage detection circuit includes a first protection resistor, a second protection resistor, a third voltage-dividing resistor, a fourth voltage-dividing resistor, an NMOS tube and a voltage-stabilizing tube, VCC is electrically connected to the first protection resistor, another pin of the first protection resistor is electrically connected to the drain of the NMOS tube, and is also electrically connected to the input end of the single-chip computer, the gate of the NMOS tube is electrically connected to the second protection resistor, VBUS is connected to the negative electrode of the voltage-stabilizing tube, the anode of the voltage-stabilizing tube is electrically connected to the third voltage-dividing resistor and the fourth voltage-dividing resistor, and the other end of the third voltage-dividing resistor is electrically connected to the gate of the NMOS tube; The current regulating circuit includes a first capacitor, a fifth voltage-dividing resistor and a sixth voltage-dividing resistor. The single chip is electrically connected to the first capacitor and is electrically connected to the charge-discharge chip through the fifth voltage-dividing resistor and the sixth voltage-dividing resistor.

2. The over-power protection circuit according to claim 1, characterized in that: The VCC is a 5V power supply voltage.

3. The over-power protection circuit according to claim 1, characterized in that: The NMOS tube is an N-channel field effect tube.

4. The over-power protection circuit according to claim 1, characterized in that: The voltage regulator tube is a 5.6V voltage regulator tube.

5. The over-power protection circuit according to claim 1, characterized in that: The first protection resistor and the second protection resistor are both thick film resistors.

6. The over-power protection circuit according to claim 1, characterized in that: The third voltage-dividing resistor, the fourth voltage-dividing resistor, the fifth voltage-dividing resistor and the sixth voltage-dividing resistor are all thick-film resistors.

7. The over-power protection circuit according to claim 1, characterized in that: The model of the single chip microcomputer is FM33LC023U.

8. The over-power protection circuit according to claim 1, characterized in that: The charging and discharging chip model is BQ24610.

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