Charge and discharge control circuit and rechargeable power supply device
View Patent ↗A charge and discharge control circuit which accommodates pulsed charge and pulsed discharge and can control charge and discharge of a secondary battery with safety, and a rechargeable power supply device having the same built therein are provided. The charge and discharge control circuit includes a delay time switching circuit for shortening a delay time of overcharge detection after charge inhibition is canceled. When overcharge is detected after the charge inhibition is canceled, the charge is inhibited in a delay time which is shorter than a normal delay time of the overcharge detection.
1. A charge and discharge control circuit for controlling charge and discharge of a secondary battery, comprising:
overcharge voltage detection means;
delay means for outputting, after receiving a signal output by the overcharge voltage detection means, the signal after a certain delay time is counted; and
delay time switching means for switching, after receiving the signal output by the overcharge voltage detection means and the signal output by the delay means, the certain delay time of the delay means, wherein:
the delay means comprises switching means for counting a first delay time and a second delay time shorter than the first delay time;
after charge inhibition is canceled from a charge inhibition state due to overcharge, the delay time switching means outputs to the delay circuit a signal for switching to the second delay time; and
the delay means detects overcharge during the second delay time.
2. A charge and discharge control circuit according to claim 1 , wherein:
the delay means further comprises timer means for recovering from the second delay time to the first delay time; and
after the timer means completes count, overcharge is detected during the first delay time.
3. A charge and discharge control circuit according to claim 2 , wherein the timer means counts a timer time which is shorter than the first delay time and longer than the second delay time.
4. A charge and discharge control circuit according to claim 2 , wherein:
the delay means further comprises a plurality of flip-flop circuits and a switch circuit; and
by dividing the plurality of flip-flop circuits by the switch circuit, the second delay time and the timer time are simultaneously counted.
5. A rechargeable power supply device, comprising:
a secondary battery;
a charge and discharge current control circuit; and
the charge and discharge control circuit according to any one of claims 1 to 4 having voltage detection terminals connected to terminals at both ends of the secondary battery, and control signal output terminals connected to the charge and discharge current control circuit,
wherein the secondary battery and the charge and discharge current control circuit are connected in series to terminals to which a charger/discharger is connected.