Method and system for detecting connection of a host device to an accessory device

An accessory device comprising:

• a first connector including a plurality of contacts, wherein the first connector is configured to connect with a second connector of a host device;
• detection circuitry coupled to the first connector;
• and
• a current source coupled to a first contact in the plurality of contacts, wherein the accessory device is operable to perform a connection detection process to determine if the accessory is electrically connected to a host electronic device, the connection detection process including:
• outputting a first voltage over the first contact;
• measuring, using the detection circuitry, a rate of rise of voltage at the first contact;
• and determining whether the accessory is connected to the host electronic device based on whether the voltage measured at the first contact meets or exceeds a threshold voltage at or after expiration of a predetermined time;
• if the accessory device determines that the host device is connected to the accessory device, initiate charging of the host electronic device to enable the host electronic device to perform an authentication process to authenticate the accessory device.

A non-transitory computer-readable storage device including a plurality of instructions, which when executed by a controller in an accessory device cause the accessory device to perform a method of determining if the accessory device is electrically connected to a host device having insufficient internal power to perform an authentication process, the plurality of instructions comprising:

• instructions that cause the accessory device to perform a connection detection to determine if the accessory is electrically connected to a host electronic device, the connection detection process including:
• outputting a first voltage over a contact of an accessory connector of the accessory device;
• measuring a voltage at the contact as a function of time;
• and determining whether the voltage measured at the contact meets or exceeds a threshold voltage at or after expiration of a predetermined time;
• if the accessory determines that the host electronic device is connected to the accessory, instructions that cause the accessory device to initiate charging of the host electronic device by enabling a first power path between the accessory device and the host device and delivering a first current level to the host device over the first power path;
• thereafter, receiving and responding to a request from the host electronic device to authenticate the accessory device to the host device;
• and upon successful authentication of the accesory device, enabling a second power path between the accessory device and the host electronic device and deliving a second current level higher than the first current level to the host device over the second power path.