Battery charger, voltage monitoring device and self-diagnosis method of reference voltage circuit

1. A battery charger comprising:

a battery cell;

a reference voltage generating section;

an A/D converting section; and

a control section,

wherein the reference voltage generating section includes a first reference voltage circuit generating a first reference voltage and a second reference voltage circuit generating a second reference voltage equal to the first reference voltage,

wherein the A/D converting section includes an A/D converter, a connection switching section, and a connection switching control section controlling the connection switching section,

wherein the control section includes a comparing section,

wherein when a charging condition of the battery cell is monitored, the control section controls the A/D converting section to connect the battery cell to the A/D converter and to output a first A/D conversion value by A/D converting a voltage value of the battery cell via the A/D converter using the first reference voltage, and the control section controls the comparing section to compare the first A/D conversion value with a predetermined first reference value,

wherein when characteristics of the A/D converter are diagnosed, the control section controls the A/D converting section to connect the A/D converting section to a first divided voltage output section outputting a first divided voltage of the first reference voltage of the first reference voltage circuit and to output a second A/D conversion value obtained by A/D converting the first divided voltage via the A/D converter using the first reference voltage, and the control section controls the comparing section to compare the second A/D conversion value with a second reference value obtained by A/D converting the first divided voltage via the A/D converter using the first reference voltage when the A/D converter is normal, and

wherein when characteristics of the first reference voltage circuit are diagnosed, the control section controls the A/D converting section to connect the A/D converting section to a second divided voltage output section outputting a second divided voltage of the second reference voltage of the second reference voltage circuit so that a voltage dividing ratio of the second divided voltage with respect to the second reference voltage is equal to a voltage dividing ratio of the first divided voltage with respect to the first reference voltage and to output a third A/D conversion value obtained by A/D converting the second divided voltage via the A/D converter using the first reference voltage, and the control section controls the comparing section to compare the third A/D conversion value with a third reference value obtained by A/D converting the first divided voltage via the A/D converter using the first reference voltage when the first reference voltage circuit is normal in a case where the A/D converter and the first reference voltage circuit are normal.

2. The battery charger according to claim 1 , wherein the control section stops a charging operation of the battery cell when the second A/D conversion value and the second reference value are not equal to each other, diagnoses the characteristics of the first reference voltage circuit when the second A/D conversion value and the second reference value are equal to each other, and stops the charging operation of the battery cell when the third A/D conversion value and the third reference value are not equal to each other.

3. A voltage monitoring device comprising:

a connection terminal to be connected to a voltage monitoring target;

a reference voltage generating section;

an A/D converting section; and

a control section,

wherein the reference voltage generating section includes a first reference voltage circuit generating a first reference voltage and a second reference voltage circuit generating a second reference voltage equal to the first reference voltage,

wherein the A/D converting section includes an A/D converter, a connection switching section, and a connection switching control section controlling the connection switching section,

wherein the control section includes a comparing section,

wherein when a voltage of the voltage monitoring target is monitored, the control section controls the A/D converting section to connect the connection terminal to the A/D converter and to output a first A/D conversion value by A/D converting a voltage value of the voltage monitoring target via the A/D converter using the first reference voltage, and the control section controls the comparing section to compare the first A/D conversion value with a predetermined first reference value,

wherein when characteristics of the A/D converter are diagnosed, the control section controls the A/D converting section to connect the A/D converting section to a first divided voltage output section outputting a first divided voltage of the first reference voltage of the first reference voltage circuit and to output a second A/D conversion value obtained by A/D converting the first divided voltage via the A/D converter using the first reference voltage, and the control section controls the comparing section to compare the second A/D conversion value with a second reference value obtained by A/D converting the first divided voltage via the A/D converter using the first reference voltage when the A/D converter is normal, and

wherein when characteristics of the first reference voltage circuit are diagnosed, the control section controls the A/D converting section to connect the A/D converting section to a second divided voltage output section outputting a second divided voltage of the second reference voltage of the second reference voltage circuit so that a voltage dividing ratio of the second divided voltage with respect to the second reference voltage is equal to a voltage dividing ratio of the first divided voltage with respect to the first reference voltage and to output a third A/D conversion value obtained by A/D converting the second divided voltage via the A/D converter using the first reference voltage, and the control section controls the comparing section to compare the third A/D conversion value with a third reference value obtained by A/D converting the first divided voltage via the A/D converter using the first reference voltage when the first reference voltage circuit is normal in a case where the A/D converter and the first reference voltage circuit are normal.

4. A self-diagnosis method of a reference voltage circuit supplying an A/D conversion reference voltage to an A/D converter comprising:

connecting an A/D converting section to a first divided voltage output section outputting a first divided voltage of the reference voltage of the reference voltage circuit, obtaining a first A/D conversion value by A/D converting the first divided voltage via the A/D converter using the reference voltage, and comparing the first A/D conversion value with a first reference value obtained by A/D converting the first divided voltage via the A/D converter using the reference voltage when the A/D converter is normal; and

connecting the A/D converting section to a second divided voltage output section outputting a second divided voltage of a second reference voltage of a second reference voltage circuit generating the second reference voltage equal to the reference voltage so that the voltage dividing ratio of the second divided voltage with respect to the second reference voltage is equal to the voltage dividing ratio of the first divided voltage with respect to the reference voltage when the first A/D conversion value is equal to the first reference value, obtaining a second A/D conversion value by A/D converting the second divided voltage via the A/D converter using the reference voltage, and comparing the second A/D conversion value with a second reference value obtained by A/D converting the first divided voltage via the A/D converter using the reference voltage when the reference voltage circuit is normal in the case where the A/D converter and the reference voltage circuit are normal.

5. The self-diagnosis method of the reference voltage circuit according to claim 4 , wherein the self-diagnosis is periodically performed.

6. The self-diagnosis method of the reference voltage circuit according to claim 4 , further comprising:

stopping the operation of a subject that is A/D converted by the A/D converting section when the first A/D conversion value and the first reference value are not equal to each other.

7. The self-diagnosis method of the reference voltage circuit according to claim 4 , further comprising:

stopping the operation of a subject that is A/D converted by the A/D converting section when the second A/D conversion value and the second reference value are not equal to each other.