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質問

What is an alarm function that is contained in the R5464 Series, a 2-cell Li-ion battery protection IC?

回答

Lithium-ion Battery Protection ICsFunction

The alarm function is adopted in order to satisfy the standard by Electrical Appliance and Material Safety Act (EAMSA) in Japan.

The alarm function outputs a signal from its alarm pin in detecting a voltage exceeding the alarm detection voltage. It changes over the alarm detection voltage based on temperature (degrees around 45°C or more). Configuring lower detection voltage than conventional overcharge detection voltage enables Li-ion battery protection ICs to output an overvoltage alarm signal to the system.

EAMSA requires that large-capacity Li-ion batteries higher than a certain value be equipped with double protection on overcharge.

A 1-cell Li-ion battery can have double protection achieved by a charger as the first protection and a 1-cell Li-ion battery protection IC as the second protection. On the other hand, with regard to 2- or multi-cell batteries, the charger can only monitor the total cell voltage and thus has no overcharge protection.
Consequently, there needs another method to achieve double protection for 2- and multi-cell batteries.

The R5464, thanks to its alarm function, can achieve 2-stage detection of high voltage with a single IC.

Example of Alarm Signal Output

Example of Alarm Signal Output-1

Example of Alarm Signal Output-2

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