IC gives lithium-ion cell discharge protection

Ricoh has introduced a battery protection IC for rechargeable one-cell lithium-ion and lithium polymer batteries which incorporates a two-step excess discharge current detector, used with an external current sense resistor.

The R5486 monitors the charge and discharge process continuously and intervenes when the process is at risk of going beyond the safe operation range of the battery cell.

Rechargeable Li-ion/Li Polymer batteries have strict operation limits to keep the battery cell in optimal condition and to prevent critical situations when overloaded.

The two-step excess discharge current detector is triggered by two critical load thresholds, where each threshold has its own response speed. The external current sense resistor measures the excess current.

Traditionally, this was measured by the mosfet on-resistance, however this parameter depends on a number of conditions making the actual overcurrent threshold inaccurate and causing a wide margin.

By using an external high precision resistor, Ricoh claims the threshold is more accurate and the margin narrows down.

The R5486 series are available in a package measuring 1.4 x 1.4 x 0.4 mm.

 

Richard Wilson

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