Chip Protects Lithium-Ion Battery Packs

Complete overvoltage, undervoltage and overcurrent protection for three- or four-cell lithium-ion battery packs is provided by the UCC3957 IC. The device has applications in both conventional and smart battery packs for laptop computers and portable instruments.The chip interfaces with external high-side, p-channel MOSFETS that prevent the loss of system ground in an undervoltage state and protect both the battery cells and the IC from damage in an overvoltage state. An internal state machine runs continuously to protect each cell from overvoltage and undervoltage fault conditions. The device operates from 6.5V to 20V with a low quiescent current of 30 µA. Four standard overvoltage thresholds are offered (4.2V, 4.25V, 4.3V and 4.35V).