Constant-current charging circuit applied to linear charger

Abstract

The invention discloses a constant-current charging circuit applied to a linear charger, mainly solving the problem of overlong charging time caused by the adoption of thermal shutdown in charging in the prior art. The circuit comprises a constant-current modulation circuit, a temperature sampling circuit, a second operational amplifier OP2 and a PMOS (p-channel metal oxide semiconductor) transistor M2; the source electrode of the PMOS transistor M2 is connected with the power supply voltage; the grid is connected with the output of the constant-current modulation circuit, and the drain electrode of the PMOS transistor M2 is the output of the charger; the constant-current modulation circuit is provided with two input ends; the first input end A is connected with the reference voltage Va so as to generate constant output current IO in constant current charging at the normal temperature; the second input end B is connected with the temperature sampling circuit through the second operational amplifier OP2 so as to form a temperature feedback control loop. By using the constant-current charging circuit provided by the invention, output current can be reduced when the temperature of a chip is high, so that the temperature of the chip can be stabilized to be within the range of refining temperature T1, and charging is continued, and thus the problem of too long charging time resulting from the adoption of thermal shutdown is avoided. The constant-current charging circuit can be used in linear chargers.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits and relates to an analog integrated circuit, in particular to a constant current charging circuit applied to a linear charger. Background technique [0002] A linear charger is mainly a system that uses linear regulated power supply technology to charge batteries. The charging method is generally a typical constant current / constant voltage mode. When charging, the main purpose is to quickly replenish the battery with a constant current. When the battery is close to full, switch to constant voltage mode, and the charging current begins to decrease until it is fully charged. [0003] figure 1 The constant current charging circuit of the existing linear charger is given, mainly including the operational amplifier OP, the resistor R, the PMOS tube M 1 and M 2 . The positive input terminal of the operational amplifier OP is connected to one end of the resistor R, and at the same time co...

AI Technical Summary

Problems solved by technology

[0008] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art, and propose a constant current charging circuit applied to a linear charger, so as to solve the problem of too long charging time caused by thermal shutdown when charging in the prior art

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