Charge and discharge protection circuit and battery pack with high withstand voltage
First Claim
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1. A charge and discharge protection circuit coupled to one of a secondary battery and a charger, for protecting the secondary battery from an overcharge state, an overdischarge state and an over-current state, comprising:
- an overcharge detecting circuit for monitoring how the secondary battery is charged and for generating an overcharge detection signal;
a level shifting circuit for receiving the overcharge detection signal from the overcharge detecting circuit and for generating a charge control signal;
an overdischarge detecting circuit for monitoring how the secondary battery discharges itself and for generating an overdischarge detection signal;
an over-current detecting circuit for detecting an over-current state of the secondary battery and for generating an over-current detection signal;
a delay circuit for setting a delay time used when one of an overdischarge state and an over-current state is detected;
a short circuit detecting circuit for detecting a short circuit state and for generating a short circuit detection signal;
a plurality of protection diodes for protection of the overcharge and overdischarge protection circuit from static electricity, and whereintransistors constituting the level shifting circuit that potentially receive a relatively high voltage from the charger as one of a source level and a drain level have a high withstand voltage construction.
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Abstract
In a charge and discharge protection circuit, those transistors constituting a level shifting circuit that may receive a relatively high voltage as a source level or a drain level have a high withstand voltage construction.
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Citations
8 Claims
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1. A charge and discharge protection circuit coupled to one of a secondary battery and a charger, for protecting the secondary battery from an overcharge state, an overdischarge state and an over-current state, comprising:
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an overcharge detecting circuit for monitoring how the secondary battery is charged and for generating an overcharge detection signal; a level shifting circuit for receiving the overcharge detection signal from the overcharge detecting circuit and for generating a charge control signal; an overdischarge detecting circuit for monitoring how the secondary battery discharges itself and for generating an overdischarge detection signal; an over-current detecting circuit for detecting an over-current state of the secondary battery and for generating an over-current detection signal; a delay circuit for setting a delay time used when one of an overdischarge state and an over-current state is detected; a short circuit detecting circuit for detecting a short circuit state and for generating a short circuit detection signal; a plurality of protection diodes for protection of the overcharge and overdischarge protection circuit from static electricity, and wherein transistors constituting the level shifting circuit that potentially receive a relatively high voltage from the charger as one of a source level and a drain level have a high withstand voltage construction. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A battery pack comprising:
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a battery cell; two terminals connected to one of a charger and a load; a charge and discharge protection circuit connected to said battery cell so as to protect said battery cell from an overcharge state, an overdischarge state and an over-current state; a discharge transistor connected in series between the load and said battery cell so as to control a discharge current supplied from said battery cell to the load; a charge transistor connected in series between the charger and said battery cell so as to control a charge current from the charger to said battery cell; a capacitor for setting a delay time used in detecting the overcharge state; wherein said charge and discharge protection circuit comprises; an overcharge detecting circuit for monitoring how the battery cell is charged and for generating an overcharge detection signal; a level shifting circuit for receiving the overcharge detection signal from the overcharge detecting circuit and for generating a charge control signal; an overdischarge detecting circuit for monitoring how the battery cell discharges itself and for generating an overdischarge detection signal; an over-current detecting circuit for detecting an over-current state of the battery cell and for generating an over-current detection signal; a delay circuit for setting a delay time used when one of an overdischarge state and an over-current state is detected; a short circuit detecting circuit for detecting a short circuit state and for generating a short circuit detection signal; a plurality of protection diodes for protection of the overcharge and overdischarge protection circuit from static electricity, and wherein transistors constituting the level shifting circuit that potentially receive a relatively high voltage from the charger as one of a source level and a drain level have a high withstand voltage construction.
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Specification