Introduction to Lithium-ion Battery Charging Protection IC Knowledge Points:

The protection circuit of lithium-ion batteries is designed to ensure safety during overcharging and over-discharging conditions, while preventing degradation of characteristics. The protection circuit for lithium-ion batteries consists of a protection IC and two Power-MOSFETs. The protection IC monitors the battery voltage; when overcharging or over-discharging occurs, it switches to an external Power-MOSFET to protect the battery. The functions of the protection IC are: (1) overcharge protection, (2) over-discharge protection, and (3) overcurrent/short-circuit protection. Below, we explain the protective actions for these three functions.

When lithium-ion batteries overcharge, the electrolyte inside can polymerize, causing the temperature to rise and generating gases, which can lead to increased pressure and pose a risk of spontaneous combustion or explosion. The purpose of the lithium-ion battery protection IC is to prevent overcharging from occurring.

Overcharge Protection IC Principle: Under over-discharge conditions, the electrolyte undergoes decomposition, leading to degradation of battery characteristics and a decrease in charge cycles. The lithium-ion battery protection IC is designed to prevent over-discharge occurrences, triggering protective actions. The over-discharge protection function can be lifted when the lithium-ion battery is connected to a charger and its voltage exceeds the over-discharge voltage.

For the phenomenon of pulse discharge, the over-discharge detection is equipped with a delay time to prevent the occurrence of such misoperation. Due to unknown reasons (such as accidental contact with metallic objects during discharge or at the positive and negative poles), overcurrent or short-circuit current may occur. To ensure safety, continuous discharge is allowed.