Procedure for charging a portable device using a battery-operated computer

A device, comprising:

• an input configured to couple to a supply voltage line;
• detection circuitry configured to couple to a port and to generate a detection signal indicating an external device is coupled to the port;
• and
• sleep-mode charge-control circuitry configured to generate a sleep-mode charge-control signal based on an indication of an intensity of a charging current of a charging voltage line and a counting signal, wherein:
• the sleep-mode charge-control circuitry comprises:
• a comparator configured to compare the intensity of the charging current to a current threshold value corresponding to an expected intensity of a charging current at an end of a charging cycle and to generate the indication of the intensity of the charging current;
• a counter configured to generate an indication a charging time has elapsed;
• and
• a logic circuit configured to generate the charge-control signal based on the detection signal, the indication of the intensity of the charging current and the indication the charging time has elapsed;
• and
• the detection circuitry comprises:
• a finite-state machine configured to supply the detection signal;
• a bypass switch configured to couple the supply voltage line to the port;
• a discharge switch configured to control discharging of capacitors coupled to the port;
• and
• a current limiter inserted on a link coupling the supply voltage line to the port, wherein the state machine is configured to receive a signal representative of a voltage drop on the link coupling the supply voltage line to the port, a signal indicating a current limit of the current limiter has been exceeded, and a signal indicating a charging voltage is present.

A system, comprising:

• one or more processors;
• a port;
• power supply circuitry configured to generate a supply voltage and a charging voltage;
• and
• a port-charging control device configured to control charging of external devices in a system sleep mode, the port-charging control device including:
• detection circuitry configured to couple to the port and to generate a detection signal indicating an external device is coupled to the port;
• and
• charge-control circuitry configured to generate a charge-control signal based on an indication of an intensity of a charging current of a charging voltage line and a counting signal, wherein:
• the charge-control circuitry includes:
• a comparator configured to compare the intensity of the charging current to a current threshold value corresponding to an expected intensity of a current at an end of a charging cycle and to generate the indication of the intensity of the charging current;
• a counter configured to generate an indication a charging time has elapsed;
• and
• a logic circuit configured to generate the charge-control signal based on the detection signal, the indication of the intensity of the charging current and the indication the charging time has elapsed;
• and
• the detection circuitry includes:
• a finite-state machine configured to supply the detection signal;
• a bypass switch configured to couple a supply voltage line to the port;
• a discharge switch configured to control discharging of capacitors coupled to the port;
• and
• a current limiter inserted on a link coupling the supply voltage line to the port, wherein the state machine is configured to receive a signal representative of a voltage drop on the link coupling the supply voltage line to the port, a signal indicating a current limit of the current limiter has been exceeded, and a signal indicating a charging voltage is present.

A system, comprising:

• means for coupling to a supply voltage line;
• means for generating a detection signal indicating an external device is coupled to a system port;
• and
• means for controlling charging of the external device based on an intensity of a charging current of a charging voltage line and a counting signal, wherein,
• the means for controlling includes:
• a comparator configured to compare the intensity of the charging current to a current threshold value corresponding to an expected intensity of a current at an end of a charging cycle and to generate an indication of the intensity of the charging current;
• a counter configured to generate an indication a charging time has elapsed;
• and
• a logic circuit configured to generate a charge-control signal based on the detection signal, the indication of the intensity of the charging current and the indication the charging time has elapsed;
• the counter is configured to indicate the charging time has elapsed when a threshold charging period has elapsed or a threshold quantity of electrical charge has been supplied to the port;
• and
• the means for generating the detection signal includes:
• a finite-state machine configured to supply the detection signal;
• a bypass switch configured to couple the supply voltage line to the port;
• a discharge switch configured to control discharging of capacitors coupled to the port;
• and
• a current limiter inserted on a link coupling the supply voltage line to the port, wherein the state machine is configured to receive a signal representative of a voltage drop on the link coupling the supply voltage line to the port, a signal indicating a current limit of the current limiter has been exceeded, and a signal indicating a charging voltage is present.