SN74LVC245DBR Datasheet, PDF (2/22 Pages) Texas Instruments – 8-BIT DUAL-SUPPLY BUS TRANSCEIVER WITH CONFIGURABLE VOLTAGE TRANSLATION AND 3-STATE OUTPUTS

SN74LVCH8T245
8-BIT DUAL-SUPPLY BUS TRANSCEIVER
WITH CONFIGURABLE VOLTAGE TRANSLATION AND 3-STATE OUTPUTS
SCES637A – AUGUST 2005 – REVISED FEBRUARY 2007
www.ti.com
DESCRIPTION/ORDERING INFORMATION (CONTINUED)
The SN74LVCH8T245 is designed for asynchronous communication between two data buses. The logic levels
of the direction-control (DIR) input and the output-enable (OE) input activate either the B-port outputs or the
A-port outputs or place both output ports into the high-impedance mode. The device transmits data from the A
bus to the B bus when the B-port outputs are activated, and from the B bus to the A bus when the A-port
outputs are activated. The input circuitry on both A and B ports is always active and must have a logic HIGH or
LOW level applied to prevent excess I_CC and I_CCZ.
The SN74LVCH8T245 is designed so that the control pins (DIR and OE) are supplied by V_CCA.
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.
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.
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⁽¹⁾
(EACH 8-BIT SECTION)
CONTROL INPUTS
OE
DIR
L
L
L
H
H
X
OUTPUT CIRCUITS
A PORT B PORT
Enabled
Hi-Z
Hi-Z
Enabled
Hi-Z
Hi-Z
OPERATION
B data to A bus
A data to B bus
Isolation
(1) Input circuits of the data I/Os are always active.
LOGIC DIAGRAM (POSITIVE LOGIC)
2
DIR
3
A1
22
OE
21
B1
To Seven Other Channels
2
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