US Patent 7728556 Semiconductor device for protecting rechargeable battery

A semiconductor device for protecting a rechargeable cell at least from excessive discharge current due to over discharge of the rechargeable cell, includes (a) a first excessive discharge current detection circuit configured to detect first excess of a voltage at an electric current detection terminal exceeding a first voltage level (Vs3), (b) a second excessive discharge current detection circuit configured to detect second excess of the absolute voltage at the electric current detection terminal exceeding a second voltage level (Vs4) higher than the first voltage level, (c) a delay circuit configured to cause each of the first and second excessive discharge current detection circuits to delay output by a predetermined delay time, and (d) a delay reducing circuit configured to produce a delay time reducing signal for reducing the delay time at a predetermined ratio.