Patent ID: 6768289
Filing Date: 2004-07-27
Classification: H02J

Abstract:
A cellular telephone comprising:a battery pack with a secondary battery and a charge/discharge protection circuit, said charge/discharge protection circuit comprising: an overcharge detection circuit which detects an overcharge of said secondary battery connected to said charge/discharge protection circuit and outputs an overcharge detection signal; a discharge over-current detection circuit which detects a discharge over-current of said secondary battery and outputs a discharge over-current detection signal; a charge control field effect transistor (FET) connected to a charge path of said secondary battery in series so as to cut off a charge current supplied to said secondary battery; a discharge control field effect transistor (FET) connected to the charge path of said secondary battery in series so as to cut off a discharge current supplied from said secondary battery; a latch circuit which latches the overcharge detection signal output from said overcharge detection circuit and outputs a signal so as to control said charge control FET; a first delay circuit which delays the discharge over-current detection signal output from said discharge over-current detection circuit and supplies the delayed discharge over-current detection signal to said discharge control FET; and a reset circuit which resets said latch circuit so as to turn on said charge control FET when the discharge over-current is detected by said discharge over-current detection circuit and when the overcharge is not detected by said overcharge detection circuit.