Overcharge and overdischarge protection for a chargeable electric cell operable with a reduced current consumption

Claim 2

A protection circuit for an electric cell, comprising: an overcharge detection circuit coupled to a chargeable electric cell, said overcharge detection circuit detecting an overcharged condition of said chargeable electric cell and outputting an overcharge detection signal responsive thereto; an overdischarge detection circuit coupled to said chargeable electric cell, said overdischarge circuit detecting an overdischarged condition of said chargeable electric cell and outputting an overdischarge detection signal responsive thereto; a switch inserted in a power supply line of said chargeable electric cell, said switch being activated responsive to the output of said overcharge and overdischarge detection signals to thereby respectively inhibit one of a charging operation and a discharging operation of said chargeable electric cell; a timing signal supplying means, coupled to at least said overcharge detection circuit, for supplying a first timing signal having a first operation timing duration t1, said timing signal supplying means cyclically supplying said first timing signal at a time interval tO, wherein t1<<t0; and a processing circuit for processing an output signal of said overcharge detection circuit activated by said first timing signal to judge a presence or an absence of an overcharged condition, said processing circuit activating said switch upon judgment of the presence of said overcharged condition.

Claim 3

A protection circuit as claimed in claim 1, wherein said timing signal supplying means includes means coupled to said processing circuit for supplying said processing circuit with a second timing signal having a second operation timing duration t2, said second timing signal being supplied within a supply period of said first timing signal, and said second timing signal having a leading edge and a trailing edge which are not coincident with a leading edge and a trailing edge of said first timing signal.

Claim 4

A protection circuit as claimed in claim 2, wherein said processing circuit includes means for activating said switch responsive to a plurality of consecutive judgements of an overcharged condition.

Claim 5

A protection circuit for an electric cell, comprising: an overcharge detection circuit coupled to a chargeable electric cell, said overcharge detection circuit detecting an overcharged condition of said chargeable electric cell and outputting an overcharge detection signal responsive thereto; an overdischarge detection circuit coupled to said chargeable electric cell, said overdischarge circuit detecting an overdischarged condition of said chargeable electric cell and outputting an overdischarge detection signal responsive thereto; a switch inserted in a power supply line of said chargeable electric cell, said switch being activated responsive to the output of said overcharge and overdischarge detection signals to thereby respectively inhibit one of a charging operation and a discharging operation of said chargeable electric cell; a timing signal supplying means, coupled to at least said overcharge detection circuit, for supplying a first timing signal having a first operation timing duration t1, said timing signal supplying means also being coupled to said processing circuit for supplying said processing circuit with a second timing signal having a second operation timing duration t2, said second timing signal being supplied within a supply period of said first timing signal, and said second timing signal having a leading edge and a trailing edge which are not coincident with a leading edge and a trailing edge of said first timing signal; and a processing circuit for processing an output signal of said overcharge detection circuit activated by said first timing signal to judge a presence or an absence of an overcharged condition, said processing circuit activating said switch upon judgment of the presence of said overcharged condition.

Claim 6

A protection circuit for an electric cell, comprising: an overcharge detection circuit coupled to a chargeable electric cell, said overcharge detection circuit detecting an overcharged condition of said chargeable electric cell and outputting an overcharge detection signal responsive thereto; an overdischarge detection circuit coupled to said chargeable electric cell, said overdischarge circuit detecting an overdischarged condition of said chargeable electric cell and outputting an overdischarge detection signal responsive thereto; a switch inserted in a power supply line of said chargeable electric cell, said switch being activated responsive to the output of said overcharge and overdischarge detection signals to thereby respectively inhibit one of a charging operation and a discharging operation of said chargeable electric cell; a timing signal supplying means, coupled to at least said overcharge detection circuit, for supplying a first timing signal having a first operation timing duration t1, said timing signal supplying means also being coupled to said processing circuit for supplying said processing circuit with a second timing signal having a second operation timing duration t2, said second timing signal being supplied within a supply period of said first timing signal, and said second timing signal having a leading edge and a trailing edge which are not coincident with a leading edge and a trailing edge of said first timing signal; and a processing circuit for processing an output signal of said overcharge detection circuit activated by said first timing signal to judge a presence or an absence of an overcharged condition, said processing circuit activating said switch upon judgment of the presence of said overcharged condition.

Claim 7

A protection circuit as claimed in claim 4, wherein said processing circuit includes means for activating said switch responsive to a plurality of consecutive judgements of an overcharged condition.