Single-cell Li-Ion/Li-Polymer battery protection chips

April 16, 2013 // By Graham Prophet
Ricoh Europe has launched two 1-Cell lithium-ion/lithium polymer battery protection ICs, the R5475 and R5478, for use in rechargeable portable electronic products, providing safety measures for the charge and discharge process in order to assure failsafe operation of the battery pack.

The IC monitors the charge and discharge process and intervenes as soon as the process is at risk of going beyond the safe operation range of the battery cell. The protection ICs can be used on the application circuit board, or integrated in a laminated battery pack. Rechargeable Li-Ion cells, in particular, must be operated within strict limits to keep the battery cell in optimal condition and to prevent a critical situation when overloaded. The R5475 and R5478 offer standard detection circuits for example, over-charge voltage, over-discharge voltage, excess-discharge current and short protection.

As soon the over-charge voltage threshold is exceeded, the chip will interrupt the charge process preventing an overload condition. In the event that the over-discharge voltage threshold is exceeded, the chip will interrupt the discharge process, entering into a standby mode lowering the current consumption and ensuring further discharge is kept to a minimum. Optional latch and auto-release functions for the over-charge and over-discharge monitoring circuits are available. A latch function keeps the chip interrupted from the charge or discharge process while an auto release function tries to resume the process to normal operation after a time out period and when the interrupt condition is resolved to normal. An excess-discharge current detector is triggered as soon the discharge current exceeds a threshold. Any further increase in load triggers a further detection level in the form of a short-circuit protection mechanism.

With 20 years of experience developing battery management ICs, Ricoh believes it has nearly 30% worldwide market share for 1-Cell Li-Ion battery protection ICs.