SN74CBT3345: voltage drop at output

Vaishnavi, 

The SN74CBT3345 device is a single NFET type signal switch.  This means as the input/output voltage approaches the supply voltage the signal path resistance Ron becomes exponentially high.  This increase in on-state resistance is due to the NFET gate to source Vgs voltage becoming less than the FET turn on threshold.

http://www.ti.com/lit/an/szza030/szza030.pdf 

If you would like to have a switch that can support I/O voltages all the way up to the supply rail you will need a device like the SN74CB3Q3345 which is an NFET with a charge pump on the gate.  This charge pump increases the gate voltage above Vcc so that the Vgs voltage stays greater than the Vt and keeps a low resistance signal path. 

Thank you,

Adam

What maximum voltage we can apply to OE?

I am making a system which will select any one setup out of 8 setups(multiplexer kind of thing).I just want to pass whatever data comes from PC(db9 connector) to whichever setup is selected using output enable pin.And I am thinking of controlling OE pin of each IC using any controller.I want to share my schematic with you so that you can tell me what is wrong in that.please try to give me demo connection diagram for 1 IC.

I have connect IC to direct 5V. OE to 5V ,GND and any one port pin from A1 to A8 is connected  to 5V and I am checking output at corrosponding B port.Only this much connection I have done and I am getting 1V drop at output.

Please let me know if anything is wrong in schematic.

Thank you in advanceswitch5.pdf