IDT74FST163P245

    The FST163245/163P245 belong to IDT's family of Bus switches.  Bus switch devices perform the function of connecting or isolating two ports without providing any inherent current sink or source capability.  Thus they generate little or no noise of their own while providing a low resistance path for an external driver.  These devices connect input and output ports through an n-channel FET.  When the gate-to-source junction of this FET is adequately forward-biased the device conducts and the resistance between input and output ports is small.  Without adequate bias on the gate-to-source junction of the FET, the FET is turned off, therefore with no V_CC applied, the device has hot insertion capability.

    The low on-resistance and simplicity of the connection between input and output ports reduces the delay in this path to close to zero.

    The FST163245 and FST163P245 are 16-bit TTL-compatible bus switches.  The OE pins provide enable control.  The FST163P245 supports precharge on the B port.  So when OE is high, A and B ports are isolated and B outputs are precharged to the bias voltage through the equivalent of a 10KΩ resistor (1B1-8 precharged to VBIAS1 and 2B1-8 precharged to VBIAS1).