Patent ID: 8339099

Claim:
A control IC comprising: a plurality of voltage input terminals configured to receive respective terminal voltages of plural respective battery cells connected in series; a multiplexer configured to select a voltage input terminal of the plurality of voltage input terminals, from which a terminal voltage is to be detected; a voltage detection circuit configured to detect the terminal voltage of the voltage input terminal selected by the multiplexer; first input and output terminals configured to receive or send a command signal and/or terminal voltages detected by the voltage detection circuit; a fault-flag input terminal and a fault-flag output terminal configured to respectively receive and send an abnormality-indicating signal which has a single first level to indicate a normal condition and a single second level to indicate an abnormal condition so that the normal condition is indicated by the single first level without the need for additional signals or levels, and so that the abnormal condition is indicated by the single second level, without the need for additional signals or levels, and wherein the control IC is configured such that the fault-flag output terminal sends the abnormality-indicating signal having the single second level when the fault-flag input terminal receives the abnormality-indicating signal having the single second level, wherein the control IC includes a battery cell abnormality detection circuit to detect an abnormality in one of the battery cells, and wherein the control IC is configured to send the abnormality-indicating signal having the single second level from the fault-flag output terminal when the battery cell abnormality detection circuit detects an abnormality in one of the battery cells.