Switching and protection circuit for standby battery of vehicle-mounted GPS (global positioning system) terminal

Abstract

The invention discloses a switching and protection circuit for a standby battery of a vehicle-mounted GPS (global positioning system) terminal. The switching and protection circuit comprises a charging chip, an electronic switch, a first voltage detection chip, a logic circuit and a second voltage detection chip, an external 5V power source is inputted in three ways, the first-way voltage is inputted to the first voltage detection chip and used for detecting input voltage, the first voltage detection chip inputs detection results to the logic circuit, the second-way voltage is directly inputted to the electronic switch, the third-way voltage is inputted to the charging chip and inputted to the electronic switch via a battery connected with the charging chip, and the electronic switch controls battery voltage output. Besides, the second voltage detection chip is connected with an output end of the electronic switch and used for detecting output battery voltage and sending detection results to the logic circuit, and the logic circuit is used for generating a judgment signal to control the electronic switch according to external power supply voltage detected by the first voltage detection chip and battery voltage inputted by the second voltage detection chip and is used for power supply switching of the external 5V power source and the battery and battery protection. By the switching and protection circuit, the standby battery can be switched on automatically when the terminal is mounted to be powered on, so that mounting and use are facilitated; and when the external power source of the terminal is cut off, outward discharge of the battery can be cut off automatically when the battery discharges to store voltage, so that deep discharge can be prevented, storage time of the terminal (battery) is prolonged, and service life of the battery can be prolonged.

Description

Technical field [0001] The invention relates to GPS terminal equipment, in particular to a vehicle-mounted GPS terminal backup battery switching protection circuit. Background technique [0002] During the process of battery discharge, if it exceeds the battery discharge termination voltage value and continues to discharge, the internal pressure of the battery may increase, the reversibility of the positive and negative active materials will be damaged, and the battery capacity will be significantly reduced, causing the battery Over-discharge; in the process of battery use, when the battery discharge capacity accounts for 100% of its rated capacity, it is called the depth of discharge. The depth of discharge has a great relationship with the charging life of the secondary battery. The deeper the depth of discharge, the shorter the charging life, so you should try to avoid deep discharge when using. Since the lithium battery is not used for a long time, the battery will be over-d...

AI Technical Summary

Problems solved by technology

[0004] It can be seen that the battery mechanical switch must be turned on when the vehicle-mounted terminal uses the battery at present, which is inconvenient to use, and the battery will be discharged until the battery protection board is protected after opening, and the battery will be deeply discharged or even over-discharged. As a result, the battery cannot be charged normally, which affects the battery life, and the terminal must replace the battery

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