If these pins are left unconnected, the inputs will be pulled down internally to VSS. If they are tied to VCC or driven high, the internal pull-down circuitry is disabled. In most applications, the chip address inputs A0, A1 and A2 are hard-wired to logic ‘0’ or logic ‘1’. For applications in which these pins are controlled by a microcontroller or other programmable device, the chip address pins must be driven to logic ‘0’ or logic ‘1’ before normal device operation can proceed.