A battery protective device that protects against battery damage and
semiconductor destruction from overdischarge and overcharge of the
battery. Resistance across switching elements is controllable to prevent
current leakage through parasitic dipole elements in the integrated
circuit. Current is detected with an overdischarge detecting circuit and
an overcharge detecting circuit. Direction of the current to/from the
battery is detected by discharge overcurrent and charge overcurrent
detecting circuits. Switching discharge FETs and charge FETs are enabled
as independently controlled, ON-OFF parallel switching elements,
interposed in series in the charge/discharge current path of the battery.
Only a part of the discharge or charge switching FETs can be turned ON
and OFF for accurate current control in accordance with the detected
current and its direction.