This 8-bit noninverting bus transceiver uses two separate configurable power-supply
rails. The SN74LVC8T245 is optimized to operate with VCCA and
VCCB set at 1.65 V to 5.5 V. The A port is designed to track
VCCA. VCCA accepts any supply voltage from 1.65 V to
5.5 V. The B port is designed to track VCCB. VCCB
accepts any supply voltage from 1.65 V to 5.5 V. This allows for universal low-voltage
bidirectional translation between any of the 1.8-V, 2.5-V, 3.3-V, and 5.5-V voltage nodes.
The SN74LVC8T245 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 ICC and ICCZ.
The SN74LVC8T245 is designed so that the control pins (DIR and OE)
are supplied by VCCA.
This device is fully specified for partial-power-down applications using
Ioff. The Ioff circuitry disables the outputs,
preventing damaging current backflow through the device when it is powered down.
The VCC isolation feature ensures that if either
VCC input is at GND, all outputs are in the high-impedance state.
To ensure the high-impedance state during power up or power down,
OE should be tied to VCC through a pullup resistor;
the minimum value of the resistor is determined by the current-sinking capability of the