Patent ID: 8362741

Claim:
A method for use by a device to distinguish between a Charging Downstream Port (“CDP”) and a Dedicated Charging Port (“DCP”), the device includes a first switch connected between a positive data line and a voltage source, a second switch connected between the positive data line and a current source, a third switch connected between a negative data line and a comparison circuit, a fourth switch connected between the voltage source and the negative data line, a fifth switch connected between the current source and the negative data line, and a sixth switch connected between the positive data line and the comparison circuit, the method comprising: detecting that the device is attached to a charging port; and determining whether the charging port is the CDP or the DCP without causing a host coupled to the CDP to be able to detect the device when the charging port is the CDP; wherein the detecting includes closing the first switch, the second switch and the third switch, and opening the fourth switch, the fifth switch and the sixth switch, and wherein the determining includes opening the first switch, the second switch and the third switch, and closing the fourth switch, the fifth switch and the sixth switch.