To safely operate such a battery, the discharge current rate and battery voltage level must be monitored. Undervoltage protection is crucial when using lithium-ion batteries because if the battery is discharged below its rated value, the battery will become damaged and potentially pose a safety hazard.
The battery protection circuit disconnects the battery from the load when a critical condition is observed, such as short circuit, undercharge, overcharge or overheating. Additionally, the battery protection circuit manages current rushing into and out of the battery, such as during pre-charge or hotswap turn on.
Considerations in choosing battery protection ICs Two important parameters in battery ICs are overvoltage threshold and undervoltage threshold. These numbers are the voltage levels at their limit; the IC will cut the cell out of circuit if the cell is being overcharged or over-discharged.
Figure 1 shows an ultralow power, precision undervoltage-lockout circuit. The circuit monitors the voltage of a Li-Ion battery and disconnects the load to protect the battery from deep discharge when the battery voltage drops below the lockout threshold.
The most important faults that the batteries must be protected from are overvoltage, overcurrent, and over temperature conditions as these can place the batteries in a dangerously unstable state. The same is true for undervoltage conditions, though to a lesser extent.
Lithium batteries have the advantage of high energy density. However, they require careful handling. This article discusses important safety and protection considerations when using a lithium battery, introduces some common battery protection ICs, and briefly outlines selection of important components in battery protection circuits. Overcharge