Octal Bus Transceiver With Adjustable Output Voltage and 3-State Outputs

This 8-bit (octal) noninverting bus transceiver uses two separate power-supply rails. The A port, VCCA, is dedicated to accepting a 5V supply level, and the configurable B port, which is designed to track VCCB, accepts voltages from 3V to 5V. This allows for translation from a 3.3V to a 5V environment and vice versa.

The SN74LVCC4245A device is designed for asynchronous communication between data

buses. The SN74LVCC4245A device transmits data from the A bus to the B bus or from

the B bus to the A bus, depending on the logic level at the direction-control (DIR)

input. The output-enable (OE) input can be used to disable the

device so the buses effectively are isolated. The control circuitry (DIR,

OE) is powered 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 is designed so that if either VCCA

or VCCB is less than 100mV, both I/O ports enter a high-impedance state

by disabling their outputs.