The battery remaining amount warning circuit can issue a battery remaining amount
warning after battery power is fully used, reduce current consumption, and issue
a warning at appropriate timing for various types of battery. A system controller
calculates DC resistance value of the battery from a difference between a current
value in an operating mode before a change which is stored in the memory and a
current value in an operating mode after the change which is stored in the memory
and a voltage variation of the battery measured by an A/D converter, and when the
calculated DC resistance value becomes greater than a predetermined value, the
system controller sends a warning instruction signal to a data LCD.
