Battery protection circuit device

1. A protection circuit device for a battery having a plurality of chargeable and dischargeable secondary batteries connected in series, the protection circuit device comprising: a plurality of reference voltage circuits each configured to generate a reference voltage for detecting a voltage of a corresponding one of the secondary batteries, each of the reference voltage circuits having a power supply terminal connected to a positive terminal of the corresponding one of the secondary batteries and having a ground terminal connected to a negative terminal of the corresponding one of the secondary batteries, and a withstanding voltage of an element forming each of the reference voltage circuits being higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of chargeable and dischargeable secondary batteries.

2. A protection circuit device for a battery having a plurality of chargeable and dischargeable secondary batteries connected in series, the protection circuit device comprising: a plurality of voltage detection circuits for detecting a voltage of a corresponding one of the secondary batteries and for comparing the detected voltage with a reference voltage to thereby detect an over-charge state and an over-discharge state of the corresponding one of the secondary batteries, each of the voltage detection circuits having a power supply terminal connected to a positive terminal of the corresponding one of the secondary batteries and having a ground terminal connected to a negative terminal of the corresponding one of the secondary batteries, and a withstanding voltage of an element forming each of the voltage detection circuits being higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of chargeable and dischargeable secondary batteries.

3. A protection circuit device for a battery having a plurality of chargeable and dischargeable secondary batteries connected in series, the protection circuit device comprising: a plurality of reference voltage circuits each for generating a reference voltage for a corresponding one of the secondary batteries; and a plurality of voltage detection circuits each for detecting a voltage of the corresponding one of the secondary batteries and for comparing the detected voltage with a corresponding one of the reference voltages generated by the reference voltage circuits to thereby detect an over-charge state and an over-discharge state of the corresponding one of the secondary batteries; wherein an output from each of the voltage detection circuits is input to a level shifter circuit, and an output from the level shifter circuit is input to a controller circuit having an operating voltage range narrowed by stepping down a power supply voltage or stepping up a ground level; wherein each of the reference voltage circuits and each of the voltage detection circuits has a power supply terminal connected to a positive terminal of the corresponding one of the secondary batteries and has a ground terminal connected to a negative terminal of the corresponding one of the secondary batteries; and wherein a withstanding voltage of elements forming each of the reference voltage circuits and voltage detection circuits is higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of chargeable and dischargeable secondary batteries.

4. A protection circuit device for a battery having a plurality of chargeable and dischargeable secondary batteries connected in series, the protection circuit device comprising:

a plurality of first electrostatic discharge (ESD) protection elements disposed between respective voltage detection terminals connected to the secondary batteries; and

a second ESD protection element disposed between a terminal of a highest potential and a terminal of a lowest potential of the secondary batteries;

wherein a withstanding voltage of each of the first ESD protection elements is higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of chargeable and dischargeable secondary batteries; and

wherein a withstanding voltage of the second ESD protection element is higher than an overall voltage of the battery having the plurality of chargeable and dischargeable secondary batteries.

5. A protection circuit device according to claim 1 ; further comprising an electrostatic discharge (ESD) protection element disposed between a terminal of a highest potential and a terminal of a lowest potential of the plurality of secondary batteries; and wherein a withstanding voltage of the ESD protection element is higher than an overall voltage of the battery having the plurality of secondary batteries.

6. A protection circuit device according to claim 1 ; further comprising a plurality of electrostatic discharge (ESD) protection elements disposed between respective voltage detection terminals connected to the plurality of secondary batteries; wherein a withstanding voltage of each of the plurality of ESD protection elements is higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of secondary batteries.

7. A protection circuit device according to claim 2 ; further comprising an electrostatic discharge (ESD) protection element disposed between a terminal of a highest potential and a terminal of a lowest potential of the plurality of secondary batteries; and wherein a withstanding voltage of the ESD protection element is higher than an overall voltage of the battery having the plurality of secondary batteries.

8. A protection circuit device according to claim 2 ; further comprising a plurality of electrostatic discharge (ESD) protection elements disposed between respective voltage detection terminals connected to the plurality of secondary batteries; wherein a withstanding voltage of each of the plurality of ESD protection elements is higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of secondary batteries.

9. A protection circuit device according to claim 3 ; further comprising an electrostatic discharge (ESD) protection element disposed between a terminal of a highest potential and a terminal of a lowest potential of the plurality of secondary batteries; and wherein a withstanding voltage of the ESD protection element is higher than an overall voltage of the battery having the plurality of secondary batteries.

10. A protection circuit device according to claim 3 ; further comprising a plurality of electrostatic discharge (ESD) protection elements disposed between respective voltage detection terminals connected to the plurality of secondary batteries; wherein a withstanding voltage of each of the plurality of ESD protection elements is higher than a voltage of one of the secondary batteries and lower than an overall voltage of the battery having the plurality of secondary batteries.

11. A protection circuit device for a battery having a plurality of secondary batteries connected in series, the protection circuit device comprising:

a reference voltage circuit for generating a reference voltage; and

a voltage detection circuit for detecting a voltage of one of the secondary batteries and comparing the detected voltage with the reference voltage generated by the reference voltage circuit to thereby detect an over-charge state and an over-discharge state of the one of the secondary batteries;

wherein each of the reference voltage circuit and the voltage detection circuit has a power supply terminal connected to a positive electrode of the one of the secondary batteries and has a ground terminal connected to a negative electrode of the one of the secondary batteries; and

wherein a withstand voltage of elements forming the reference voltage circuit and the voltage detection circuit is set to be lower than an overall voltage of the plurality of secondary batteries.

12. A protection circuit device according to claim 11 ; further comprising an electrostatic discharge (ESD) protection element disposed between a terminal of a highest potential and a terminal of a lowest potential of the plurality of secondary batteries; and wherein a withstanding voltage of the ESD protection element is higher than an overall voltage of the plurality of secondary batteries.

13. A protection circuit device according to claim 11 ; further comprising an electrostatic discharge (ESD) protection element disposed between voltage detection terminals connected to the one of the secondary batteries; wherein a withstanding voltage of the ESD protection element is higher than a voltage of the one of the secondary batteries and lower than an overall voltage of the plurality of secondary batteries.