Battery-operated equipment including a microcomputer

1. A battery-operated equipment comprising:

a battery;

a constant voltage power source that derives a constant voltage from a battery voltage across said battery; and

a microcomputer that incorporates at least an A/D converter and has terminals for the A/D converter and a power input terminal,

said microcomputer being connected with said battery via said power input terminal to use said battery voltage as a power source voltage,

said A/D converter being connected with said constant voltage power source via a specific terminal of said terminals for the A/D converter to use said constant voltage as a voltage for the A/D converter, and

said A/D converter being connected with said constant voltage power source via a reference voltage input terminal of the A/D converter as said specific terminal to use said constant voltage as a reference voltage for the A/D conversion.

2. A battery-operated equipment, comprising:

a battery;

a constant voltage power source that derives a constant voltage from a battery voltage across said battery; and

a microcomputer that incorporates at least and A/D converter and has terminals for the A/D converter and a power input terminal,

said microcomputer being connected with said battery via said power input terminal to use said battery voltage as a power source voltage,

said A/D converter being connected with said constant voltage power source via a specific terminal of said terminals for the A/D converter to use said constant voltage as a voltage for the A/D converter,

wherein said microcomputer has an analog input terminal of said A/D converter as said specific terminal and also has a reference voltage input terminal of said A/D converter as another terminal of said terminals for the A/D converter; and

said A/D converter is connected with said constant voltage power source via said analog input terminal to use said constant voltage as an input voltage for the A/D conversion and is also connected with said battery via said reference voltage input terminal to use said battery voltage as a reference voltage for the A/D conversion.

3. The battery-operated equipment of claim 1 , further comprising an indication circuit that indicates operating state of said battery-operated equipment according to control of said microcomputer, wherein:

said microcomputer further has a control terminal; and

said indication circuit is connected with said control terminal to receive said control and also connected with said battery to use said battery voltage as the power source voltage.

4. The battery-operated equipment of claim 2 , further comprising an indication circuit that indicates operating state of said battery-operated equipment according to control of said microcomputer, wherein:

said microcomputer further has a control terminal; and

said indication circuit is connected with said control terminal to receive said control and also connected with said battery to use said battery voltage as the power source voltage.

5. The battery-operated equipment of claim 1 , further comprising a motor that is connected with said battery to use said battery voltage as the power source voltage of the motor.

6. The battery-operated equipment of claim 2 , further comprising a motor that is connected with said battery to use said battery voltage as the power source voltage of the motor.

7. The battery-operated equipment of claim 1 , wherein:

said battery is a secondary battery; and

said constant voltage power source increases and decreases said constant voltage on charging and discharging of said battery, respectively.

8. The battery-operated equipment of claim 2 , wherein:

said battery is a secondary battery; and

said constant voltage power source increases and decreases said constant voltage on charging and discharging of said battery, respectively.