ILSI America offers a line of crystal oscillators that includes the following types: XO, VCXO TCXO, TCVCXO, and OCXO. Many of these crystal oscillators offer tri-state control. The three state output or tri-state controlled crystal oscillators are common in applications that include automated testing and bus writing data transfer. The three states are low, high and high impedance. An output in the high impedance state behaves as if it is disconnected from the circuit except for possibility of a small leakage current. Please contact us at (775) 851-8880, for more information on crystal oscillators that are best suited for your application.