Abstract: In a general aspect, a charging apparatus can include a power converter circuit configured to supply, from an input voltage, charging power for charging a battery of an electronic device; and a control circuit configured to determine a charging current limit and a charging voltage of the power converter circuit for charging the battery. Determining the charging current limit and the charging voltage can include: setting the current limit of the power converter circuit to an initial charging current limit and setting the charging voltage to an initial charging voltage; determining whether the power converter circuit is operating in a current limit mode or a voltage limit mode; and iteratively modifying the current limit of the power converter circuit until the power converter circuit dithers between the current limit mode and the voltage limit mode.

Abstract: In accordance with an embodiment, a bypass charging circuit includes a pair of transistors having current carrying terminals commonly connected to form a node. An input of a comparator is coupled to the node through a switch and to a resistor. Another input terminal of the comparator is coupled for receiving a reference voltage. Optionally, a transistor may be connected to the bypass charging circuit. In accordance with another embodiment a method is provided in which bypass charging transistors are coupled to first input of a comparator in response to closing a switch. A voltage is generated at the first input of the comparator in response to closing the switch and the voltage is compared with a reference voltage. In response to the comparison, a status indicator signal is generated to indicate the presence of a low-impedance failure in one or both of the bypass charging transistors.

Abstract: In a general aspect, a charging apparatus can include a power converter circuit configured to supply, from an input voltage, charging power for charging a battery of an electronic device; and a control circuit configured to determine a charging current limit and a charging voltage of the power converter circuit for charging the battery. Determining the charging current limit and the charging voltage can include: setting the current limit of the power converter circuit to an initial charging current limit and setting the charging voltage to an initial charging voltage; determining whether the power converter circuit is operating in a current limit mode or a voltage limit mode; and iteratively modifying the current limit of the power converter circuit until the power converter circuit dithers between the current limit mode and the voltage limit mode.

Abstract: In accordance with an embodiment, a bypass charging circuit includes a pair of transistors having current carrying terminals commonly connected to form a node. An input of a comparator is coupled to the node through a switch and to a resistor. Another input terminal of the comparator is coupled for receiving a reference voltage. Optionally, a transistor may be connected to the bypass charging circuit. In accordance with another embodiment a method is provided in which bypass charging transistors are coupled to first input of a comparator in response to closing a switch. A voltage is generated at the first input of the comparator in response to closing the switch and the voltage is compared with a reference voltage. In response to the comparison, a status indicator signal is generated to indicate the presence of a low-impedance failure in one or both of the bypass charging transistors.