Optocoupler isolation charging protection circuit and lithium battery

Abstract

The utility model provides an optocoupler isolation charging protection circuit. The optocoupler isolation charging protection circuit comprises a photoelectric coupler, a first resistor and a second resistor. One end of the first resistor is connected with the charging protection control signal end of the MCU and the input end anode of the photoelectric coupler, and the other end is connected with the input end cathode of the photoelectric coupler and grounded. One end of the second resistor is connected with the driving voltage signal end and the photoelectric coupler output end collector, and the other end is connected with the photoelectric coupler output end emitter and grounded. According to the circuit, a charging protection control signal of the MCU is utilized, and the driving voltage signal level of the control end of the battery charging MOS tube is adjusted by controlling the on-off of the photoelectric coupler. When charging is completed or a fault occurs, the charging MOS tube can be rapidly closed, so that a charging loop is cut off, the charging safety of the lithium battery is ensured, and the reliability of the optocoupler isolation charging protection circuit is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of lithium battery charging protection, and particularly relates to a photoelectric coupling isolation charging protection circuit and a lithium battery. BACKGROUND

[0002] Lithium batteries have been widely used in mobile base station energy storage and daily electronic products due to their environmental protection, small size and other advantages. However, the charging safety problem of lithium batteries has always been an important issue that cannot be ignored. In the charging process, the problem of overheat, fire and even explosion of lithium batteries caused by short circuit is prone to occur.

[0003] There are various lithium battery charging protection methods in the prior art. Some chargers control the charging current by detecting the voltage of the lithium battery, and stop charging when the voltage reaches a certain value. Some chargers use charging communication to establish communication between the charger and the battery, read the charging capacity of the battery, and stop outputting current when the capacity reaches the requirement. However, this method can achieve charging protection, and needs to rely on the charger to achieve, rather than the lithium battery itself. When the charger fails, there is a risk of protection failure.

[0004] For example, the prior art document CN201110446765.4 discloses a charging circuit and a charger. When the DC power supply is connected to the charging circuit, the voltage stabilizing chip immediately stabilizes the voltage to provide stable power for the single-chip microcomputer to start charging preparation. After the charging load is connected, the single-chip microcomputer intelligently senses and starts charging, and finely controls the charging current through the PWM signal. During the charging process, the single-chip microcomputer monitors the voltage and current, and cuts off the charging when an abnormality is found. After the charging is completed, the single-chip microcomputer automatically stops working to ensure that the charging process is safe and efficient. However, this scheme is used in the charger, and when the charger fails, there is still a risk that the charging circuit cannot be protected. UTILITY MODEL CONTENT

[0005] The purpose of the present disclosure is to overcome the deficiencies in the prior art and provide a photoelectric coupling isolation charging protection circuit.

[0006] The purpose of the present disclosure is achieved by the following technical solutions:

[0007] A photoelectric coupling isolation charging protection circuit, comprising a photoelectric coupler, a first resistor and a second resistor, a first end of the first resistor is used for being connected with a charging protection control signal end of an MCU, the first end of the first resistor is also connected with a positive electrode of an input end of the photoelectric coupler, a second end of the first resistor is connected with a negative electrode of the input end of the photoelectric coupler, and the negative electrode of the input end of the photoelectric coupler is grounded.

[0008] The first end of the second resistor is connected with a driving voltage signal end, the first end of the second resistor is also connected with a collector of the optoelectronic coupler output end, the second end of the second resistor is connected with an emitter of the optoelectronic coupler output end, and the emitter of the optoelectronic coupler output end is grounded.

[0009] In one of the embodiments, the optoelectronic coupler isolation charging protection circuit further comprises a third resistor, the first end of the third resistor is connected with a charging protection control signal end of the MCU, and the second end of the third resistor is connected with a positive electrode of an input end of the optoelectronic coupler.

[0010] In one of the embodiments, the resistance ratio of the first resistor to the third resistor ranges from 0.83 to 10.

[0011] In one of the embodiments, the optoelectronic coupler input end is connected with a red light emitting diode, and the resistance ratio of the first resistor to the third resistor ranges from 0.83 to 2.67.

[0012] In one of the embodiments, the resistance ratio of the first resistor to the third resistor is 1.2.

[0013] In one of the embodiments, the optoelectronic coupler input end is connected with a green light emitting diode, and the resistance ratio of the first resistor to the third resistor ranges from 1.54 to 10.

[0014] In one of the embodiments, the resistance ratio of the first resistor to the third resistor is 3.13.

[0015] In one of the embodiments, at least one of the first resistor, the second resistor and the third resistor is a variable resistor.

[0016] In one of the embodiments, the optoelectronic coupler isolation charging protection circuit further comprises a short-circuit protection filter capacitor, and the positive electrode of the input end of the optoelectronic coupler is grounded through the short-circuit protection filter capacitor.

[0017] A lithium battery comprising the optoelectronic coupler isolation charging protection circuit according to any one of the above embodiments.

[0018] Compared with the prior art, the present disclosure has at least the following advantages:

[0019] The optoelectronic coupler isolation charging protection circuit can control the level output of the driving voltage signal of the battery charging MOS tube control end through the output signal of the charging protection control signal end of the MCU, so as to timely turn off the charging MOS tube when the lithium battery is charged or a fault occurs during the charging process, thereby cutting off the charging circuit and ensuring the charging safety of the lithium battery, and improving the reliability of the optoelectronic coupler isolation charging protection circuit. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a circuit diagram of an embodiment of an optocoupler-isolated charging protection circuit. Detailed Implementation

[0022] To facilitate understanding of this disclosure, a more complete description will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the present disclosure. However, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] To better understand the technical solutions and beneficial effects of this disclosure, the following detailed description is provided in conjunction with specific embodiments:

[0026] like Figure 1 As shown, an embodiment of the optocoupler isolated charging protection circuit 10 of this disclosure includes an optocoupler U1, a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is used to connect to the charging protection control signal terminal Charge_OK of the MCU. The first end of the first resistor R1 is also connected to the positive terminal 1 of the input terminal of the optocoupler. The second end of the first resistor R1 is connected to the negative terminal 2 of the input terminal of the optocoupler. The negative terminal 2 of the input terminal of the optocoupler is grounded.

[0027] The first end of the second resistor R2 is connected with the driving voltage signal terminal CHG_12V, and the first end of the second resistor R2 is also connected with the collector 4 of the output terminal of the photoelectric coupler, the second end of the second resistor R2 is connected with the emitter 3 of the output terminal of the photoelectric coupler, and the emitter 3 of the output terminal of the photoelectric coupler is grounded.

[0028] In the embodiment, when the lithium battery starts to be charged, the driving voltage signal terminal CHG_12V is in a high level state and provides a driving voltage for the control terminal of the battery charging MOS tube, at this time, the battery charging MOS tube is opened, allowing the external charger to supply power to the battery, so that the battery is in a normal charging state: during the charging process, if the lithium battery is normal and the charging stop condition is not reached, the MCU controls the charging protection control signal terminal Charge_OK to keep low level. At this time, the light emitting diode of the input terminal of the photoelectric coupler U1 is extinguished, so that the output terminal of the photoelectric coupler U1 keeps off state, the driving voltage signal terminal CHG_12V continues to be in high level state and provides a driving voltage for the control terminal of the battery charging MOS tube, so that the battery charging process continues. When the battery is fully charged or the MCU detects a fault, the MCU controls the charging protection control signal terminal Charge_OK to output a high level signal, so that the current flows into the anode of the input terminal of the photoelectric coupler U1, so that the light emitting diode of the input terminal of the photoelectric coupler U1 is lighted, the output terminal of the photoelectric coupler U1 is turned on, and then the driving voltage signal terminal CHG_12V is connected with the ground terminal through the output terminal of the photoelectric coupler U1, so that the voltage of the driving voltage signal terminal CHG_12V is pulled to low level state. At this time, the control terminal of the battery charging MOS tube is in off state due to the loss of sufficient driving voltage, so as to cut off the charging circuit to realize the charging protection of the battery.

[0029] The photoelectric coupler isolation charging protection circuit 10 described above controls the on-off of the photoelectric coupler U1 through the output signal of the charging protection control signal terminal Charge_OK of the MCU, so as to control the level output of the driving voltage signal terminal CHG_12V of the control terminal of the battery charging MOS tube, so as to realize the timely closing of the charging MOS tube after the lithium battery is fully charged or a fault occurs in the charging process, and then cut off the charging circuit and ensure the charging safety of the lithium battery, and improve the reliability of the photoelectric coupler isolation charging protection circuit 10.

[0030] As Figure 1As shown in the figure, in one embodiment, the photo-coupling isolation charging protection circuit 10 further comprises a third resistor R3, a first end of the third resistor R3 is connected with the charging protection control signal end Charge_OK of the MCU, and a second end of the third resistor R3 is connected with the positive pole 1 of the input end of the photo-coupler. In this embodiment, since the third resistor R3 is connected in series between the charging protection control signal end Charge_OK and the positive pole 1 of the input end of the photo-coupler, and the current flowing through each element in the series circuit is equal, according to Ohm's law, the voltage across each element in the circuit is proportional to its resistance value, therefore the third resistor R3 plays a role of voltage division and current limiting in the circuit, avoiding the problem that the current flowing through the input end of the photo-coupler U1 is too large, causing damage to the photo-coupler U1, thereby ensuring that the photo-coupler U1 can work normally.

[0031] As shown in the figure, Figure 1 In one embodiment, the resistance ratio of the first resistor R1 and the third resistor R3 is in the range of 0.83-10. In this embodiment, since the first resistor R1 and the third resistor R3 are connected in series, and the input end of the photo-coupler U1 is connected with both ends of the first resistor R1, the voltage across the first resistor R1 is equal to the input end voltage of the photo-coupler U1, when the battery is fully charged or the MCU detects a fault, the MCU controls the charging protection control signal end Charge_OK to output a high-level signal, the voltage value of the high-level signal is 3.3V, and since the input end of the photo-coupler U1 is connected with a light-emitting diode, the conduction voltage range of a conventional visible light-emitting diode is between 1.5V and 3.0V, therefore the resistance ratio of the first resistor R1 and the third resistor R3 needs to meet the conduction voltage range of the visible light-emitting diode, according to Ohm's law and the characteristics of the series circuit, it can be calculated that the resistance ratio of the first resistor R1 and the third resistor R3 is in the range of 0.83-10, thereby making the input end of the photo-coupler U1 be able to select a variety of light-emitting diodes, thereby improving the flexibility of the photo-coupling isolation charging protection circuit 10.

[0032] As shown in the figure, Figure 1 In one embodiment, the input end of the photo-coupler U1 is connected with a red light-emitting diode, and the resistance ratio of the first resistor R1 and the third resistor R3 is in the range of 0.83-2.67. In this embodiment, when the input end of the photo-coupler U1 selects a red light-emitting diode, since the conduction voltage range of the red visible light-emitting diode is between 1.5V and 2.4V, therefore the resistance ratio of the first resistor R1 and the third resistor R3 needs to meet the conduction voltage range of the light-emitting diode, according to Ohm's law and the characteristics of the series circuit, it can be calculated that the resistance ratio of the first resistor R1 and the third resistor R3 is in the range of 0.83-2.67, thereby making the photo-coupler U1 be able to select a conventional red light-emitting diode as the light source of the input end.

[0033] AsFigure 1 As shown, in one embodiment, the resistance ratio of the first resistor R1 to the third resistor R3 is 1.2. In this embodiment, since the typical forward voltage of a red visible light emitting diode is 1.8V, the resistance ratio of the first resistor R1 to the third resistor R3 needs to be selected to ensure that the emitting diode can operate normally under its forward voltage. According to Ohm's law and the characteristics of series circuits, the resistance ratio of the first resistor R1 to the third resistor R3 is calculated to be 1.2, thereby ensuring that the optocoupler U1 can operate stably and normally.

[0034] like Figure 1 As shown, in one embodiment, the input terminal of optocoupler U1 is connected to a green light-emitting diode (LED), and the resistance ratio of the first resistor R1 to the third resistor R3 is within the range of 1.54 to 10. In this embodiment, when a green LED is selected as the input terminal of optocoupler U1, since the conduction voltage range of a green visible light LED is between 2V and 3V, the resistance ratio of the first resistor R1 to the third resistor R3 must meet the conduction voltage range of the LED. According to Ohm's law and the characteristics of series circuits, the resistance ratio of the first resistor R1 to the third resistor R3 is calculated to be within the range of 1.54 to 10, thereby allowing optocoupler U1 to use a conventional green LED as the light source for its input terminal.

[0035] like Figure 1 As shown, in one embodiment, the resistance ratio of the first resistor R1 to the third resistor R3 is 3.13. In this embodiment, since the typical forward voltage of a green visible light-emitting diode is 2.5V, the resistance ratio of the first resistor R1 to the third resistor R3 needs to be selected to ensure that the light-emitting diode can operate normally under its forward voltage. According to Ohm's law and the characteristics of series circuits, the resistance ratio of the first resistor R1 to the third resistor R3 is calculated to be 3.13, thereby ensuring that the optocoupler U1 can operate stably and normally.

[0036] like Figure 1 As shown, in one embodiment, at least one of the first resistor R1, the second resistor R2, and the third resistor R3 is a variable resistor. In this embodiment, by adjusting the resistance value of the adjustable resistor, parameters such as current and voltage in the circuit can be precisely adjusted to meet different operating requirements. When the optocoupler U1 needs to connect to different light-emitting diodes, adjusting the resistance value can ensure that the circuit can work normally under different types of light-emitting diodes, thereby improving the versatility and compatibility of the circuit.

[0037] like Figure 1As shown, in one embodiment, the optical coupling isolation charging protection circuit 10 further comprises a short-circuit protection filter capacitor C1, and the positive electrode of the input end of the optoelectronic coupler U1 is connected to the ground through the short-circuit protection filter capacitor C1. In this embodiment, when the circuit is in normal operation, the short-circuit protection filter capacitor C1 can maintain stable signal transmission and current flow in the circuit, and when a short circuit occurs in the circuit, the short-circuit protection filter capacitor C1 can absorb the energy in the short-circuit current through its energy storage characteristics, thereby ensuring the safe operation of the entire system. In addition, the short-circuit protection filter capacitor C1 can filter out high-frequency noise and interference signals at the input end of the optoelectronic coupler U1, thereby ensuring that the optoelectronic coupler U1 receives stable signals, and further improving the stability of the optical coupling isolation charging protection circuit 10.

[0038] A lithium battery comprising the optical coupling isolation charging protection circuit 10 according to any one of the above embodiments. In this embodiment, when the lithium battery starts charging, the drive voltage signal terminal CHG_12V is in a high level state and provides a drive voltage for the control terminal of the battery charging MOS tube, at this time the battery charging MOS tube is opened, allowing the external charger to supply power to the battery, so that the battery is in a normal charging state: during the charging process, if the lithium battery is in a normal state and the charging stop condition is not reached, the MCU controls the charging protection control signal terminal Charge_OK to remain in a low level state. At this time, the input end of the optoelectronic coupler U1 is not conductive, so that the output end of the optoelectronic coupler U1 remains in a cut-off state, and the drive voltage signal terminal CHG_12V continues to be in a high level state and provides a drive voltage for the control terminal of the battery charging MOS tube, thereby allowing the battery charging process to continue. When the battery is fully charged or the MCU detects a fault, the MCU controls the charging protection control signal terminal Charge_OK to output a high level signal, so that the current flows into the positive electrode of the input end of the optoelectronic coupler U1, thereby causing the light-emitting diode of the optoelectronic coupler to light up, and the output end of the optoelectronic coupler U1 is conductive, thereby causing the drive voltage signal terminal CHG_12V to be connected to the ground through the output end of the optoelectronic coupler U1, so that the voltage of the drive voltage signal terminal CHG_12V is pulled to a low level state. At this time, the control terminal of the battery charging MOS tube loses sufficient drive voltage and is in a cut-off state, thereby cutting off the charging circuit to achieve charging protection for the battery.

[0039] Compared with the prior art, the present disclosure has at least the following advantages:

[0040] 1. The optical coupling isolation charging protection circuit 10 described above, the output signal of the charging protection control signal end Charge_OK of the MCU controls the on-off of the photoelectric coupler U1, the level output of the drive voltage signal end CHG_12V of the battery charging MOS tube control end is controlled, so that the lithium battery can be closed in time after the charging is completed or the charging process fails, and then the charging circuit is cut off and the safety of the lithium battery charging is ensured, and the reliability of the optical coupling isolation charging protection circuit 10 is improved.

[0041] The above-described embodiments only express several embodiments of the present disclosure, and the description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the disclosed patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present disclosure, several modifications and improvements can be made, which are within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure patent should be subject to the appended claims.

Claims

1. An opto-coupler isolated charge protection circuit, comprising: The optoelectronic coupler, a first resistor and a second resistor, a first end of the first resistor is used for connecting with a charging protection control signal end of the MCU, the first end of the first resistor is also connected with a positive input end of the optoelectronic coupler, a second end of the first resistor is connected with a negative input end of the optoelectronic coupler, and the negative input end of the optoelectronic coupler is grounded; A first end of the second resistor is used for connecting with a driving voltage signal end, the first end of the second resistor is also connected with a collector of an output end of the optoelectronic coupler, a second end of the second resistor is connected with an emitter of the output end of the optoelectronic coupler, and the emitter of the output end of the optoelectronic coupler is grounded.

2. The optical coupling isolation charge protection circuit of claim 1, wherein, The optoelectronic coupler, a first resistor and a second resistor, a first end of the first resistor is used for connecting with a charging protection control signal end of the MCU, the first end of the first resistor is also connected with a positive input end of the optoelectronic coupler, a second end of the first resistor is connected with a negative input end of the optoelectronic coupler, and the negative input end of the optoelectronic coupler is grounded; 3. The optical coupling isolation charge protection circuit of claim 2, wherein, The resistance ratio of the first resistor and the third resistor is in the range of 0.83-10.

4. The optical coupling isolation charge protection circuit of claim 2, wherein, The optoelectronic coupler input end is connected with a red light emitting diode, and the resistance ratio of the first resistor and the third resistor is in the range of 0.83-2.

67.

5. The optical coupling isolation charge protection circuit of claim 4, wherein, The resistance ratio of the first resistor and the third resistor is 1.

2.

6. The optical coupling isolation charge protection circuit of claim 2, wherein, The optoelectronic coupler input end is connected with a green light emitting diode, and the resistance ratio of the first resistor and the third resistor is in the range of 1.54-10.

7. The optical coupling isolation charge protection circuit of claim 6, wherein, The resistance ratio of the first resistor and the third resistor is 3.

13.

8. The optical coupling isolation charge protection circuit of claim 2, wherein, At least one of the first resistor, the second resistor and the third resistor is a variable resistor.

9. The optical coupling isolation charge protection circuit of claim 1, wherein, The optoelectronic coupler, a first resistor and a second resistor, a first end of the first resistor is used for connecting with a charging protection control signal end of the MCU, the first end of the first resistor is also connected with a positive input end of the optoelectronic coupler, a second end of the first resistor is connected with a negative input end of the optoelectronic coupler, and the negative input end of the optoelectronic coupler is grounded; 10. A lithium battery, characterized by, The optoelectronic coupler, a first resistor and a second resistor, a first end of the first resistor is used for connecting with a charging protection control signal end of the MCU, the first end of the first resistor is also connected with a positive input end of the optoelectronic coupler, a second end of the first resistor is connected with a negative input end of the optoelectronic coupler, and the negative input end of the optoelectronic coupler is grounded;

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