The datasheet http://ww1.microchip.com/downloads/e...Doc/21223H.pdf says

2.6 Hold (HOLD)
The HOLD pin is used to suspend transmission to the
25XX640 while in the middle of a serial sequence without
having to retransmit the entire sequence over
again. It must be held high any time this function is not
being used.

So tie the HOLD pin high.