Accessory for a portable computing device

An accessory for use with a portable computing device, the accessory comprising:

• an accessory interface configured to connect to an additional accessory and to provide power to the additional accessory;
• a portable computing device interface configured to connect to the portable computing device and to receive power from the portable computing device;
• and
• circuitry configured to operate at either of a first operating voltage or a second operating voltage, the first operating voltage corresponding to the accessory and the second operating voltage corresponding to the additional accessory;
• wherein the circuitry is further configured to operate only at the second operating voltage if the additional accessory is connected to the accessory interface and to operate only at the first operating voltage if the additional accessory is not connected.