Datasheet
SCDS159B − OCTOBER 2003 − REVISED MARCH 2004
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description/ordering information (continued)
The SN74CB3T3384 is a high-speed TTL-compatible FET bus switch with low ON-state resistance (r
on
),
allowing for minimal propagation delay. The device fully supports mixed-mode signal operation on all data I/O
ports by providing voltage translation that tracks V
CC
. The SN74CB3T3384 supports systems using 5-V TTL,
3.3-V LVTTL, and 2.5-V CMOS switching standards, as well as user-defined switching levels (see Figure 1).
V
CC
≈V
CC
5.5 V
0 V
NOTE A: If the input high voltage (V
IH
) level is greater than or equal to V
CC
− 1 V, and less than or equal to 5.5 V, the output high
voltage (V
OH
) level will be equal to approximately the V
CC
voltage level.
Input Voltages Output Voltages
0 V
≈V
CC
− 1 V ≈V
CC
− 1 V
V
CC
IN OUT
CB3T
Figure 1. Typical DC-Voltage-Translation Characteristics
The SN74CB3T3384 is organized as two 5-bit bus switches with separate ouput-enable (1OE
, 2OE) inputs. It
can be used as two 5-bit bus switches or as one 10-bit bus switch. When OE
is low, the associated 5-bit bus
switch is ON, and the A port is connected to the B port, allowing bidirectional data flow between ports. When
OE
is high, the associated 5-bit bus switch is OFF, and a high-impedance state exists between the A and B ports.
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 5-bit bus switch)
INPUT
INPUT/OUTPUT
FUNCTION
INPUT
OE
INPUT/OUTPUT
A
FUNCTION
L B A port = B port
H Z Disconnect