Interface circuits and communication system for coupling a host device to an accessory device and method for communication between such devices

Accessory interface circuit (IF2) to be implemented in an accessory device (ADEV) containing an active device (AUD), the accessory interface circuit (IF2) suitable for coupling the accessory device (ADEV) to a host device (HDEV) via a data cable (4PAC), the accessory interface circuit (IF2) configured to

• operate in a power mode of operation when connected to a host device (HDEV) being capable of providing a power supply for operating the active device (AUD) via a first line (LM) of the data cable (4PAC);
• to couple a power input of the active device (AUD) to the first line (LM) when operating in the power mode;
• and
• to couple a data input of the active device (AUD) to a second line (LR) of the data cable (4PAC) when operating in the power mode.

Method for communication between a host device (HDEV) and an accessory device (ADEV), wherein the method comprises

• connecting the host device (HDEV) and the accessory device (ADEV) via a data cable (4PAC);
• detecting, by means of the host device (HDEV), whether the accessory device (ADEV) is compatible with a power supply via a first line (LM) of the data cable (4PAC);
• operating the host device (HDEV) in a power mode of operation or in a legacy mode of operation depending on the detection;
• providing a power supply from the host device (HDEV) to the accessory device (ADEV) via the first line (LM) when the host device (HDEV) is operated in the power mode;
• and
• coupling a legacy terminal (MICS) of the host device (HDEV) to the first line (LM) when the host device (HDEV) is operated in the legacy mode.

Method for communication between a host device (HDEV) and an accessory device (ADEV) with an active device (AUD), wherein the method comprises

• connecting the host device (HDEV) and the accessory device (ADEV) via a data cable (4PAC);
• detecting, by means of the accessory device (HDEV), whether the host device (HDEV) is capable of providing a power supply for operating the active device (AUD) via a first line (LM) of the data cable (4PAC);
• operating the accessory device (HDEV) in a power mode of operation depending on the detection;
• coupling a power input of the active device (AUD) to the first line (LM) when the accessory device (ADEVD) is operated in the power mode;
• and
• coupling a data input of the active device (AUD) to a second line (LR) of the data cable (4PAC) when the accessory device (ADEV) is operated in the power mode.