A memory device includes; a first memory chip including a first on-die Termination (ODT) circuit comprising a first ODT resistor, a second memory chip including a second ODT circuit comprising a second ODT resistor, at least one chip enable signal pin that receives at least one chip enable signal, wherein the at least one chip enable signal selectively enables at least one of the first memory chip and the second memory chip, and an ODT pin commonly connected to the first memory chip and the second memory chip that receives an ODT signal, wherein the ODT signal defines an enable period for at least one of the first ODT circuit and the second ODT circuit, and in response to the ODT signal and the at least one chip enable signal, one of the first ODT resistor and the second ODT resistor is enabled to terminate a signal received by at least one of the first memory chip and the second memory chip.