A method of operation of a flash integrated circuit (IC) memory device is described. The flash IC memory device has an array of memory cells and an interface to receive control, address and data signals using an internal reference voltage. The method includes, at boot-up, initializing the internal reference voltage to a default voltage. At boot-up, the interface is operable to receive, using the internal reference voltage, signals having a first voltage swing at a first signaling frequency. The method includes receiving a first command that specifies calibration of the interface during a calibration mode. The calibration mode is used to calibrate the interface to operate at a second signaling frequency and receive signals having a second voltage swing. The second voltage swing is smaller than the first voltage swing and the second signaling frequency is higher than the first signaling frequency.