A first semiconductor device equalizes levels of a bit line and a complementary bit line of a high-order bit line pair in a first memory block using a first drive voltage signal whose level is controlled when a power-down mode or a self-refresh mode is activated according to a level combination of high-order command/address signals. A second semiconductor device equalizes levels of a bit line and a complementary bit line of a low-order bit line pair in a second memory block using a second drive voltage signal whose level is controlled when the power-down mode or the self-refresh mode is activated according to a level combination of low-order command/address signals.