A lithium battery overcharge protection circuit for shavers

Abstract

The present invention discloses a lithium battery overcharge protection circuit for a shaver, comprising a chip IC1, a power supply terminal VCC, a resistor R3, a resistor R2 and a transistor Q2, wherein the power supply terminal VCC is electrically connected to one end of the resistor R3, an end of the resistor R3 away from the power supply terminal VCC is electrically connected to the 5-pin of the chip IC1, the power supply terminal VCC is electrically connected to one end of the resistor R2, an end of the resistor R2 away from the power supply terminal VCC is electrically connected to the collector of the transistor Q2, the base of the transistor Q2 is electrically connected to the 7-pin of the chip IC1, and the emitter of the transistor Q2 is grounded. The present invention discloses a lithium battery overcharge protection circuit for a shaver, wherein no current is long to charge the battery regardless of whether the battery is fully charged or not.

Description

Technical Field

[0001] The invention belongs to the technical field of battery protection circuits, and in particular relates to a lithium battery overcharge protection circuit for a shaver. Background Art

[0002] At present, all electric shavers on the market use lithium batteries as power sources and need to be charged. In order to protect the lithium batteries, the charging circuit is equipped with corresponding protection circuits, such as Figure 1 As shown. This charging protection circuit has a defect, that is, when the battery BT1 voltage is less than the normal working voltage of the chip IC1 [below 2.0V], even if the external VCC voltage is connected, because the chip IC1 has no normal working voltage, the 7th pin cannot output the start voltage, so Q2 makes it impossible for the B pole to have a high potential, so Q1 cannot be turned on, and Q1 cannot connect to the charging power supply path, resulting in no charging response. To solve this technical phenomenon, the industry currently has the following two solutions.

[0003] like Figure 2 The solution shown is solution 1. A resistor R1 can be connected at both ends of Q1. When IC1 has no normal working voltage and Q1 cannot be turned on, the VCC current will provide the chip IC1 with working voltage through R1 and D1, so that IC1 can start working normally. The disadvantages of this solution are: R1 is fixed in the circuit. If the battery is sufficient and does not need to be charged, IC1 detects that the battery is sufficient, the 7th pin will output low, Q2 will be closed, and Q1 will also be closed, but VCC will always have current through R1 to charge the battery, which can easily cause the battery to be overcharged.

[0004] like Figure 3 The solution shown is solution 2. When IC1 has no normal working voltage, R3 provides Q2 with a start voltage, which can force Q1 to turn on and provide the chip with a normal working voltage. The disadvantage of this solution is that R3 is fixed in the circuit. If the chip pin 7 is poorly soldered due to process or IC1 is damaged, R3 will still keep Q2 turned on, which may easily cause the battery to overcharge and cause danger.

[0005] In summary, the charging protection circuit in the prior art has potential charging safety risks and needs further improvement. Summary of the invention

[0006] The main purpose of the present invention is to provide a lithium battery overcharge protection circuit for a shaver, which has no current overcharge for charging the battery regardless of whether the battery is fully charged or not.

[0007] Another object of the present invention is to provide a lithium battery overcharge protection circuit for a shaver, which will not be forcibly connected to cause safety hazards when the chip has no power or is poorly soldered.

[0008] To achieve the above purpose, the present invention discloses a lithium battery overcharge protection circuit for a shaver, comprising a chip IC1, a power supply terminal VCC, a resistor R3, a resistor R2 and a transistor Q2, wherein the power supply terminal VCC is electrically connected to one end of the resistor R3, an end of the resistor R3 away from the power supply terminal VCC is electrically connected to pin 5 of the chip IC1, the power supply terminal VCC is electrically connected to one end of the resistor R2, an end of the resistor R2 away from the power supply terminal VCC is electrically connected to the collector of the transistor Q2, the base of the transistor Q2 is electrically connected to the 7th transistor of the chip IC1, the emitter of the transistor Q2 is grounded, the internal lead of the pin 5 of the chip IC1 is connected to a diode D1 and a diode D2, the pin 5 of the chip IC1 is electrically connected to the common terminal of the diode D1 and the diode D2, the cathode of the diode D1 is electrically connected to the VDD terminal, and the anode of the diode D2 is grounded.

[0009] As a further preferred technical solution of the above technical solution, the lithium battery overcharge protection circuit of the shaver also includes a field effect transistor Q1, the source of the field effect transistor Q1 is electrically connected to the power supply terminal VCC, and the gate of the field effect transistor Q1 is electrically connected to an end of the resistor R2 away from the power supply terminal VCC.

[0010] As a further preferred technical solution of the above technical solution, the lithium battery overcharge protection circuit of the shaver also includes a diode D3, the anode of the diode D3 is electrically connected to the drain of the field effect transistor Q1, and the cathode of the diode D3 is electrically connected to pin 2 of the chip IC1.

[0011] As a further preferred technical solution of the above technical solution, the lithium battery overcharge protection circuit of the shaver further includes a battery BT1, the positive electrode of the battery BT1 is electrically connected to the cathode of the diode D3, and the negative electrode of the battery BT1 is grounded.

[0012] As a further preferred technical solution of the above technical solution, pin 8 of the chip IC1 is grounded. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a prior art circuit diagram of the present invention.

[0014] Figure 2 It is a prior art circuit diagram of the present invention.

[0015] Figure 3 It is a prior art circuit diagram of the present invention.

[0016] Figure 4 The invention discloses a lithium battery overcharge protection circuit diagram of a shaver.

[0017] Figure 5 The invention discloses a lithium battery overcharge protection circuit diagram of a shaver. DETAILED DESCRIPTION

[0018] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0019] See attached figure Figure 1 , Figure 1 This is a prior art circuit diagram of a lithium battery overcharge protection circuit for a shaver of the present invention. Figure 2 This is a prior art circuit diagram of a lithium battery overcharge protection circuit for a shaver of the present invention. Figure 3 This is a prior art circuit diagram of a lithium battery overcharge protection circuit for a shaver of the present invention. Figure 4 This is a lithium battery overcharge protection circuit diagram of a shaver of the present invention. Figure 5 The invention discloses a lithium battery overcharge protection circuit diagram of a shaver.

[0020] In the preferred embodiments of the present invention, those skilled in the art should note that the resistors, batteries, etc. involved in the present invention may be regarded as prior art.

[0021] Preferred embodiments.

[0022] The invention discloses a lithium battery overcharge protection circuit for a shaver, comprising a chip IC1, a power supply terminal VCC, a resistor R3, a resistor R2 and a transistor Q2, wherein the power supply terminal VCC is electrically connected to one end of the resistor R3, one end of the resistor R3 away from the power supply terminal VCC is electrically connected to pin 5 of the chip IC1, the power supply terminal VCC is electrically connected to one end of the resistor R2, one end of the resistor R2 away from the power supply terminal VCC is electrically connected to the collector of the transistor Q2, the base of the transistor Q2 is electrically connected to transistor 7 of the chip IC1, the emitter of the transistor Q2 is grounded, the internal lead of pin 5 of the chip IC1 is connected to a diode D1 and a diode D2, the pin 5 of the chip IC1 is electrically connected to the common terminal of the diode D1 and the diode D2, the cathode of the diode D1 is electrically connected to the VDD terminal, and the anode of the diode D2 is grounded.

[0023] Specifically, the lithium battery overcharge protection circuit of the shaver further includes a field effect transistor Q1, a source of the field effect transistor Q1 is electrically connected to the power supply terminal VCC, and a gate of the field effect transistor Q1 is electrically connected to an end of the resistor R2 away from the power supply terminal VCC.

[0024] More specifically, the lithium battery overcharge protection circuit of the shaver further includes a diode D3, an anode of the diode D3 is electrically connected to the drain of the field effect transistor Q1, and a cathode of the diode D3 is electrically connected to pin 2 of the chip IC1.

[0025] Furthermore, the lithium battery overcharge protection circuit of the shaver also includes a battery BT1, the positive electrode of the battery BT1 is electrically connected to the cathode of the diode D3, and the negative electrode of the battery BT1 is grounded.

[0026] Preferably, pin 8 of the chip IC1 is grounded.

[0027] Preferably, through the technical solution of the present invention, the power supply terminal VCC is connected to the 5th pin of the chip IC1 through the resistor R3 and is connected to VDD through the diode D1 at the upper end of the 5th pin to provide normal working voltage for the chip IC1.

[0028] It is worth mentioning that the technical features such as resistors and batteries involved in the patent application of this invention should be regarded as prior art. The specific structure, working principle and possible control method and spatial layout method of these technical features can be selected by conventional methods in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated.

[0029] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A lithium battery overcharge protection circuit for a shaver, characterized in that: It includes a chip IC1, a power supply terminal VCC, a resistor R3, a resistor R2 and a transistor Q2, wherein the power supply terminal VCC is electrically connected to one end of the resistor R3, one end of the resistor R3 away from the power supply terminal VCC is electrically connected to the 5-pin of the chip IC1, the power supply terminal VCC is electrically connected to one end of the resistor R2, one end of the resistor R2 away from the power supply terminal VCC is electrically connected to the collector of the transistor Q2, the base of the transistor Q2 is electrically connected to the 7-tube of the chip IC1, the emitter of the transistor Q2 is grounded, the internal lead of the 5-pin of the chip IC1 is connected to a diode D1 and a diode D2, the 5-pin of the chip IC1 is electrically connected to the common terminal of the diode D1 and the diode D2, the cathode of the diode D1 is electrically connected to the VDD terminal, and the anode of the diode D2 is grounded; The lithium battery overcharge protection circuit of the shaver further includes a field effect transistor Q1, the source of the field effect transistor Q1 is electrically connected to the power supply terminal VCC, and the gate of the field effect transistor Q1 is electrically connected to an end of the resistor R2 away from the power supply terminal VCC; The lithium battery overcharge protection circuit of the shaver further includes a diode D3, an anode of the diode D3 is electrically connected to the drain of the field effect transistor Q1, and a cathode of the diode D3 is electrically connected to pin 2 of the chip IC1; The lithium battery overcharge protection circuit of the shaver further comprises a battery BT1, wherein the positive electrode of the battery BT1 is electrically connected to the cathode of the diode D3; Pin 8 of the chip IC1 is grounded.

2. The lithium battery overcharge protection circuit for a shaver according to claim 1, characterized in that: The negative electrode of the battery BT1 is grounded.

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