Datasheet


      
      
SCDS128A − SEPTEMBER 2003 − REVISED OCTOBER 2003
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description/ordering information (continued)
This device is fully specified for partial-power-down applications using I
off
. The I
off
feature ensures that
damaging current will not backflow through the device when it is powered down. The device has isolation during
power off.
To ensure the high-impedance state during power up or power down, OE
should be tied to V
CC
through a pullup
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
FUNCTION TABLE
(each bus switch)
INPUT
INPUT/OUTPUT
FUNCTION
INPUT
OE
INPUT/OUTPUT
A
FUNCTION
L B A port = B port
H Z Disconnect
logic diagram (positive logic)
1A
1OE
SW
1B
2A
2OE
SW
2B
2
1
5
7
3
6
simplified schematic, each FET switch (SW)
A
EN
†
B
†
EN is the internal enable signal applied to the switch.
Undershoot
Protection Circuit