Datasheet


   
      
SCES587B − AUGUST 2004 − REVISED APRIL 2005
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
circuitry disables the outputs,
preventing damaging current backflow through the device when it is powered down.
The V
CC
isolation feature ensures that if either V
CC
input is at GND, then both ports are in the high-impedance
state.
Active bus-hold circuitry holds unused or undriven inputs at a valid logic state. Use of pullup or pulldown resistors
with the bus-hold circuitry is not recommended.
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.
terminal assignments
123456
A 1DIR NC NC NC NC 1OE
B 1B2 1B1 GND GND 1A1 1A2
C 1B4 1B3 V
CCB
V
CCA
1A3 1A4
D 1B6 1B5 GND GND 1A5 1A6
E 1B8 1B7 1A7 1A8
F 2B1 2B2 2A2 2A1
G 2B3 2B4 GND GND 2A4 2A3
H 2B5 2B6 V
CCB
V
CCA
2A6 2A5
J 2B7 2B8 GND GND 2A8 2A7
K 2DIR NC NC NC NC 2OE
NC − No internal connection
FUNCTION TABLE
(each 8-bit section)
INPUTS
OPERATION
OE
DIR
OPERATION
L L B data to A bus
L H A data to B bus
H X Isolation
GQL OR ZQL PACKAGE
(TOP VIEW)
J
H
G
F
E
D
C
B
A
213465
K