Charger for portable terminal equipment having on-hook/off-hook detecting means and battery identifying means

A charger for portable terminal equipment, said charger being capable of selectively charging a first battery pack and a second battery pack;

• said first battery pack having a pair of first charging terminals, a first auxiliary terminal, and a thermistor connected to said first auxiliary terminal;
• said second battery pack having a pair of second charging terminals and a second auxiliary terminal grounded;
• said charger comprising:
• a charging circuit;
• a pair of third charging terminals connected to said charging circuit and adapted to be selectively connected to one of said pair of first charging terminals of said first battery pack and said pair of second charging terminals of said second battery pack;
• a third auxiliary terminal adapted to be selectively connected to one of said first auxiliary terminal of said first battery pack and said second auxiliary terminal of said second battery pack, said third auxiliary terminal being connected to a power source through a pull-up resistor;
• first means for comparing a voltage at said third auxiliary terminal with a first reference voltage and detecting one of an on-hook condition and an off-hook condition of said portable terminal equipment, said first reference voltage being set lower than a voltage at said third auxiliary terminal;
• second means for comparing the voltage at said third auxiliary terminal with a second reference voltage lower than said first reference voltage and distinguishing said first battery pack and said second battery pack, said second reference voltage being set lower than a voltage at said third auxiliary terminal when said portable terminal equipment having said first battery pack is on-hooked;
• means for detecting full charge of said first battery pack;
• and
• means for cutting off an output power from said pair of third charging terminals according to a detection of the full charge of said first battery pack.