CN201985584U - Charging circuit for lithium iron phosphate charging battery - Google Patents

Abstract

The utility model discloses a charging circuit for a lithium iron phosphate rechargeable battery, comprising a USB interface for introducing an external power supply, a positive terminal and a negative terminal, the ground connection GND of the USB interface is connected to the negative terminal, and the USB interface A first diode and a second diode are connected in series between the positive voltage connection VBUS and the positive terminal, one of the first diode and the second diode is a silicon diode, and the other is a germanium diode. The utility model solves the voltage matching problem between the USB interface and the rechargeable battery through a simple circuit on the one hand, and realizes the necessary charging control function on the other hand. This circuit is simple to manufacture and low in cost, and can effectively replace the existing A complex charging circuit structure, in addition, the lithium iron phosphate rechargeable battery charger made based on the charging circuit of the utility model also has the advantages of convenience and wide application range.

Description

A charging circuit for a lithium iron phosphate rechargeable battery

technical field

The utility model relates to a battery charging circuit, in particular to a charging circuit for a lithium iron phosphate rechargeable battery.

Background technique

Compared with traditional lead-acid batteries, nickel-cadmium batteries, and nickel-hydrogen batteries, lithium iron phosphate rechargeable batteries have the advantages of safety, high stability, environmental protection, and low price, so their applications will become more and more extensive, especially as With the proposal of various battery usage schemes, it will also become possible for this lithium iron phosphate rechargeable battery with an output voltage of about 3.2V to replace the traditional disposable battery with an output voltage of about 1.5V. With the increasing use of lithium iron phosphate batteries, how to charge them conveniently has become a problem that must be solved. Traditional charging circuits are complex and costly to manufacture, and are not suitable for popularization and use.

Contents of the invention

In order to solve the above problems, the utility model provides a simple and low-cost lithium iron phosphate rechargeable battery charging circuit. The lithium iron phosphate battery charger based on this circuit has the advantages of convenience and wide application range.

The technical scheme that the utility model adopts for solving its problem is:

A charging circuit for a lithium iron phosphate rechargeable battery, comprising a USB interface for introducing an external power supply, a positive terminal for connecting to the positive pole of the lithium iron phosphate rechargeable battery, and a negative terminal for connecting to the negative pole of the lithium iron phosphate rechargeable battery , the ground connection GND of the USB interface is connected to the negative terminal, the first diode and the second diode are connected in series between the positive voltage connection VBUS of the USB interface and the positive terminal, and the anode of the first diode It is connected to the positive voltage connection VBUS, the cathode of the first diode is connected to the anode of the second diode, the cathode of the second diode is connected to the positive terminal, and one of the first diode and the second diode One is a silicon diode and the other is a germanium diode.

The DC voltage introduced by the USB interface is generally between 4.75V and 5.25V, while the charging voltage of the lithium iron phosphate rechargeable battery is generally between 3.7V and 4.3V. The voltage introduced by the USB interface cannot be directly used for phosphoric acid The iron-lithium rechargeable battery is charged. In order to match the voltages of the two, the utility model connects a silicon diode and a germanium diode in series between the positive voltage connection VBUS and the positive terminal of the USB interface, wherein the forward voltage drop of the silicon diode is 0.7 V is about V, while the forward voltage drop of the germanium diode is about 0.3V. After the iron-lithium rechargeable battery has been charged for a period of time, the voltage at both ends will gradually rise. At this time, the path between the positive voltage connection VBUS of the USB interface and the positive terminal is automatically cut off, and the battery is no longer charged. According to the above description, the utility model solves the voltage matching problem between the USB interface and the rechargeable battery through a simple circuit on the one hand, and also realizes the necessary charging control function on the other hand. This circuit is simple to manufacture and low in cost. Effectively replace the existing various complex charging circuit structures. In addition, because the external power supply is introduced through the USB interface, the USB interface can be easily plugged into a common USB port. Therefore, based on the charging circuit of the present invention, the The prepared lithium iron phosphate rechargeable battery charger also has the advantages of convenience and wide application range.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described:

Fig. 1 is the circuit schematic diagram of the utility model.

Detailed ways

Referring to Fig. 1, a charging circuit of a lithium iron phosphate rechargeable battery of the present invention includes a USB interface 1 for introducing an external power supply, a positive electrode terminal 2 for connecting with the positive electrode of the lithium iron phosphate rechargeable battery, and a connection terminal 2 for connecting with the phosphoric acid lithium iron phosphate rechargeable battery. The negative terminal 3 connected to the negative pole of the iron-lithium rechargeable battery, the ground connection GND of the USB interface 1 is connected to the negative terminal 3, and the positive voltage connection VBUS of the USB interface 1 and the positive terminal 2 are connected in series with a first diode The tube 4 and the second diode 5, the anode of the first diode 4 is connected to the positive voltage connection VBUS, the cathode of the first diode 4 is connected to the anode of the second diode 5, and the second diode 5 The cathode of the cathode is connected to the positive terminal 2, one of the first diode 4 and the second diode 5 is a silicon diode, and the other is a germanium diode, and the arrangement order of the silicon diode and the germanium diode is not limited. It can be a structure that first passes through a silicon diode and then a germanium diode, or a structure that first passes through a germanium diode and then a silicon diode. When it is necessary to charge the lithium iron phosphate battery, the user only needs to connect the two poles of the battery to the positive terminal 3 and the negative terminal 4 in the correct direction, and then plug the USB interface 1 into the USB power supply provided by the computer. The lithium iron phosphate battery can be charged on the terminal and other positions.

The charging principle of this charging circuit is described below: the DC voltage introduced by USB interface 1 is generally between 4.75V and 5.25V, while the charging voltage of lithium iron phosphate rechargeable battery is generally between 3.7V and 4.3V. 1. The voltage introduced cannot be directly used to charge the lithium iron phosphate rechargeable battery. In order to match the voltages of the two, the utility model connects a silicon diode and a silicon diode in series between the positive voltage connection VBUS of the USB interface and the positive terminal 3. For germanium diodes, the forward voltage drop of silicon diodes is about 0.7V, while the forward voltage drop of germanium diodes is about 0.3V. The voltage introduced by the USB interface becomes about 3.75V~4.3V after being stepped down by two diodes. In addition, when the lithium iron phosphate rechargeable battery is charged for a period of time, the voltage at both ends will gradually increase. The voltage difference between the two terminals is not enough to drive the two diodes to conduct. At this time, the path between the positive voltage connection VBUS of the USB interface 1 and the positive terminal 2 is automatically cut off, and the battery is no longer charged. Therefore, the utility model solves the voltage matching problem between the USB interface 1 and the rechargeable battery through a simple circuit on the one hand, and realizes the necessary charging control function on the other hand.

The above are only illustrations and descriptions of some preferred embodiments of the utility model, but the implementation of the utility model is not limited by the above examples, as long as it achieves the technical effect of the utility model by basically the same means, it should be Belong to the protection scope of the utility model.

Claims (1)

1. A charging circuit for a lithium iron phosphate rechargeable battery, characterized in that it includes a USB interface (1) for introducing an external power supply, a positive terminal (2) for connecting to the positive pole of the lithium iron phosphate rechargeable battery, and a The negative terminal (3) connected to the negative pole of the lithium iron phosphate rechargeable battery, the ground wire GND of the USB interface (1) is connected to the negative terminal (3), the positive voltage connection VBUS of the USB interface (1) and the positive terminal ( 2) The first diode (4) and the second diode (5) are connected in series, the anode of the first diode (4) is connected to the positive voltage connection VBUS, the first diode (4) The cathode of the second diode (5) is connected to the anode of the second diode (5), the cathode of the second diode (5) is connected to the positive terminal (2), the first diode (4) and the second diode (5) ) is a silicon diode and the other is a germanium diode.

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