Method and apparatus for battery charging

A battery charging circuit for determining charge status during charging of a rechargeable battery, the circuit comprising:

• a recharge input;
• a recharge output;
• a switching element electrically coupled in series between the recharge input and the recharge output;
• a battery voltage input;
• and
• a recharge controller, coupled to the battery voltage input and the switching element, that maintains the switching element in a conducting state wherein recharge current flows from the recharge input to the recharge output until the battery voltage input reaches a threshold voltage, and that then during a periodic interval switches the switching element between a non-conducting state wherein the recharge current does not flow to the recharge output and that samples the battery voltage input to determine a charge state of a battery coupled to the recharge output and a conducting state, wherein during the periodic interval the battery voltage is allowed to stabilize during a settling period before measurement, and the battery voltage is sampled during each periodic interval until the battery maintains the threshold voltage, indicating a full charge of the battery.

A wireless communication unit comprising:

• a battery charging circuit for determining charge status during charging of a rechargeable battery, the circuit comprising:
• a recharge input;
• a recharge output;
• a switching element electrically coupled in series between the recharge input and the recharge output;
• a battery voltage input;
• and
• a recharge controller, coupled to the battery voltage input and the switching element, that maintains the switching element in a conducting state wherein recharge current flows from the recharge input to the recharge output until the battery voltage input reaches a threshold voltage, and that then during a periodic interval switches the switching element between a non-conducting state wherein the recharge current does not flow to the recharge output and that samples the battery voltage input to determine a charge state of a battery coupled to the recharge output and a conducting state, wherein during the periodic interval the battery voltage is allowed to stabilize during a settling period before measurement, and the battery voltage is sampled during each periodic interval until the battery maintains the threshold voltage, indicating a full charge of the battery.