The li ion battery charger charger's workflow

The li ion battery charger charger's workflow

The disadvantage of lithium ion batteries is that it is very demanding for the charger and needs to protect the circuit. The charging mode of Li ion battery is constant current and constant voltage mode. To effectively use battery capacity, lithium ion battery needs to be charged to the maximum voltage, but over voltage charging will cause battery damage, which requires higher control accuracy. In addition, the battery with low voltage needs to be precharged. The charger is best equipped with heat protection and time protection to provide additional protection for the battery. Therefore, a safe and effective li-ion battery charger is necessary for lithium ion batteries.

I. li ion battery charger Initialization the charging period

Lithium ion battery charger will detect the battery and charging power after initializing the charging cycle. After charging, if the battery voltage is less than 3.89V or THERM pin voltage is higher than 1.4V, it will recharge. The condition of fast charging is that the battery voltage is greater than 2.5V and less than the charging threshold voltage (the default value is 4.2V), and the temperature range is 2.5°C～47.5°C. If the temperature range does not match, the li-ion battery charger will be in wait state. When the battery voltage is less than 2.5V, the lithium ion battery charger pre charged with 5mA, which prevents the deep discharge of li-ion battery from being damaged or even dangerous when it is fast charging.

II. li ion battery charger Fast charging process

After fast charging, the lithium ion battery charger opens the external P channel field effect tube, and the charging current is determined by the external current limiting charging power supply. Because in the switch state P channel field-effect tube is not linear regulator, so the power consumption is very small, fast charging end condition is the battery voltage reaches a threshold (adjusted by the ADJ pin) or the charging time to fast charging time or temperature beyond the predetermined temperature exceeds the working range, fast charging is suspended, when the temperature recovery after the fast charge will continue.

III. li ion battery charger Pulse charging process

In most cases the battery reaches the threshold after the end of fast charging process into the pulse charging process, li-ion battery charger detected every 2ms a battery voltage, battery voltage is less than the threshold, the external P channel field-effect tube, the battery voltage is greater than or equal to the threshold value, the P channel field-effect tube is disconnected, the pulse charging process near the end, the opening time greatly exceeds the turn-on time of P channel field-effect tube, TSEL tube feet are arranged to period ratio (1/64,1/128,1/256) after the end of charging process of pulse.

IV. li ion battery charger Charging status indication CHG

Between pin CHG and pin IN connection LED as a state of charge indicator light, when not inserted into the battery or power is not connected or the battery voltage is less than 2.2V when the CHG pin is high impedance state, LED is not bright; when the fast charge or pulse charging when the LED light, during initialization or time exceeds a predetermined time. According to the 50% LED cycle flash; when the state of charge at the end, according to the 12% LED cycle flash.