Constant current charger circuit

Abstract

The invention discloses a constant current charger circuit, solving the problems of charging current precision and circuit stability caused by offset voltage in the process of lithium battery charging. The constant current charger circuit is characterized in that a sampling unit (2) samples a charging unit (1) to obtain a sampling current signal IBFETH; a switched capacitor circuit unit (3), a voltage compensation unit (4) and a signal conversion unit (5) form negative feedback to ensure the sampling precision. The sampling current signal IBFETH is converted into a sampling voltage by the signal conversion unit (5) and output to a charging current adjustment unit (6). The charging current adjustment unit (6) obtains the charging current adjusting signal according to the sampling voltage and feeds back the obtained signal to the charging unit (1) for controlling and adjusting the magnitude of the constant current charging current. A digital control unit (7) is used to switch the working state of the switched capacitor circuit unit (3) to eliminate the influence of the offset voltage of an operational amplifier. The constant current charger circuit makes the charging current maintain accurate and stable under different offset voltages, and can be used for a lithium battery charger.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, in particular to a high-precision and high-stability constant-current charging circuit, which can be used in a single-cell lithium battery charger. Background technique [0002] With the popularity of mobile phones, tablets, and wearable electronic devices, power management for these mobile electronic devices has become more and more important. Lithium batteries are widely used in mobile electronic devices due to their high operating voltage and long life. According to the chemical characteristics of lithium batteries, the most popular charging method is the three-stage charging method: trickle charging, constant current charging, and constant voltage charging. Among them, constant current charging occupies the main process of lithium battery charging. [0003] figure 1 It is a schematic diagram of a traditional lithium battery constant current charging circuit. Among them, SYS is...

AI Technical Summary

Problems solved by technology

At this time, it is easy to make the current exceed the adjustment range of the constant current charging loop, and the constant current charging function will fail.

Nowadays, with the continuous increase of battery capacity and the strict requirements of users on charging time, the constant current charging current will continue to increase, which means that the circuit stability problem caused by the offset voltage will be continuously amplified

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