System, method and semiconductor device for charging a secondary battery

A system comprising:

• a housing;
• a rechargeable battery within the housing;
• a semiconductor device within the housing, the semiconductor device including a processor and a charging circuit, wherein the battery charging circuit comprises:
• an adjustable current source to supply charge to the rechargeable battery;
• and
• a feedback control module having a first input responsive to a voltage level at the rechargeable battery and a second input responsive to a limit voltage, and having an output directed to control the current supplied by the adjustable current source;
• wherein the feedback control module selectively provides a signal to turn off the current supplied by the adjustable current source and wherein a voltage at the rechargeable battery is measured during a time period when the current is turned on and during a time period when the current is turned off.

A method of charging a battery, the method comprising:

• applying a charging current from a semiconductor device to a the battery during a first battery charging time period;
• measuring a charging voltage level at the battery during the first battery charging time period;
• and
• during a non-charging voltage measurement time interval, temporarily stopping application of the charging current from the semiconductor device to the battery and concurrently measuring a non-charging voltage level at the battery while the charging current is no longer being applied to the battery.

A method for charging a battery, the method comprising:

• receiving a charging current having a substantially constant value at a terminal of the battery while a battery voltage is below a limit voltage;
• receiving a charging current having a decreasing value at the terminal while the battery voltage is at or near the limit voltage;
• and
• periodically, receiving no charging current while the charging current is generally decreasing.