High-side current-sensing smart battery charger

A battery powered device comprising:

• a battery for energizing operation of the device;
• a buck converter circuit that is adapted for receiving electrical energy from an external power source and supplying electrical energy for charging said battery, said buck converter circuit including a series switch that receives an electrical current from the external power source and that supplies an electrical current to said battery during charging thereof, said buck converter circuit also including a current-sensing resistor connected in series between the external power source said battery through which flows electrical current supplied to said battery during charging thereof;
• and
• a battery charger IC adapted for controlling operation of said buck converter circuit, said battery charger IC including:
• a pulse-width-modulation switch drive circuit for supplying to the series switch during charging of said battery an electrical signal adapted for repeatedly turning-on and then turning-off the series switch included in said buck converter circuit;
• and
• a charging-current sense amplifier for receiving from the current-sensing resistor and for amplifying an electrical signal which represents the electrical current supplied to said battery during charging thereof, said charging-current sense amplifier including a bridge circuit to which is coupled the electrical signal received from the current-sensing resistor.

A battery powered device comprising:

• a battery for energizing operation of the device;
• a buck converter circuit that is adapted for receiving electrical energy from an external power source and supplying electrical energy for charging said battery, said buck converter circuit including a series switch that receives an electrical current from the external power source and that supplies an electrical current to said battery during charging thereof, said buck converter circuit also including a current-sensing resistor connected in series between the external power source said battery through which flows electrical current supplied to said battery during charging thereof;
• a battery charger IC adapted for controlling operation of said buck converter circuit, said battery charger IC including:
• a pulse-width-modulation switch drive circuit for supplying to the series switch during charging of said battery an electrical signal adapted for repeatedly turning-on and then turning-off the series switch included in said buck converter circuit;
• and
• a charging-current sense amplifier for receiving from the current-sensing resistor and for amplifying an electrical signal which represents the electrical current supplied to said battery during charging thereof, said charging-current sense amplifier including an auto-zero portion which automatically compensates for long-term drift or mismatch occurring within said charging-current sense amplifier.