Charge and discharge control circuit
First Claim
1. A charge and discharge control circuit comprising:
- a pair of external connection terminals connected when in use to a power source;
a switch circuit connected between the power source and at least one of the external connection terminals;
an overcurrent detection element connected in series with the power source for producing an output voltage in accordance with a current flowing therethrough;
a voltage detecting circuit for determining whether the output voltage of the overcurrent detection element is above any of a plurality of overcurrent detection voltage levels and outputting an overcurrent detection signal for controlling the switch circuit to disconnect the power source from the external connection terminal; and
a delay circuit for delaying the overcurrent detection signal by a variable delay time having a value which varies depending upon the level of the output voltage of the overcurrent detection element.
2 Assignments
0 Petitions
Accused Products
Abstract
A plurality of combinations of overcurrent detection voltages and delay times are set in a charge and discharge control circuit. Accordingly, a charge and discharge control circuit is formed in which an overcurrent condition having unexpectedly large consumption current, such as a short circuit, does not damage the circuit. In one embodiment, the charge and discharge control circuit comprises a pair of external connection terminals connected to a secondary cell, a switch circuit connected between the cell and at least one of the external connection terminals, an overcurrent detection element connected in series with the power source for producing an output voltage in accordance with a current flowing therethrough, a voltage detecting circuit for determining whether the output voltage of the overcurrent detection element is above one of a plurality of overcurrent detection voltage levels and outputting an overcurrent detection signal for controlling the switch circuit to disconnect the power source from the external connection terminal, and a delay circuit for delaying the overcurrent detection signal by a delay time which depends upon the level of the output voltage of the overcurrent detection element.
23 Citations
17 Claims
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1. A charge and discharge control circuit comprising:
- a pair of external connection terminals connected when in use to a power source;
a switch circuit connected between the power source and at least one of the external connection terminals;
an overcurrent detection element connected in series with the power source for producing an output voltage in accordance with a current flowing therethrough;
a voltage detecting circuit for determining whether the output voltage of the overcurrent detection element is above any of a plurality of overcurrent detection voltage levels and outputting an overcurrent detection signal for controlling the switch circuit to disconnect the power source from the external connection terminal; and
a delay circuit for delaying the overcurrent detection signal by a variable delay time having a value which varies depending upon the level of the output voltage of the overcurrent detection element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- a pair of external connection terminals connected when in use to a power source;
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11. A charge and discharge control circuit comprising:
- a secondary cell;
external connection terminals connected to the secondary cell and being connectable to a load for supplying power to the load and to a charging device for charging the secondary cell;
a switch circuit connected in series between the secondary cell and at least one of the external connection terminals;
an overcurrent detection circuit connected with the secondary cell for outputting an overcurrent detection signal for controlling the switch circuit to disconnect the secondary cell from the external connection terminals when the current through the secondary cell is above one of a plurality of values; and
a delay circuit for delaying the overcurrent detection signal by a variable delay time having a value which varies in accordance with the level of current through the secondary cell. - View Dependent Claims (12, 13, 14, 15, 16, 17)
- a secondary cell;
Specification