This 8-bit (octal) noninverting bus
transceiver contains two separate supply rails; B port has VCCB, which is
set at 3.3V, and A port has VCCA, which is set at 5V. This allows for
translation from a 3.3V to a 5V environment, and vice versa.
The SN74LVC4245A device is designed
for asynchronous communication between data buses. The 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 are effectively isolated. The
control circuitry (DIR, OE) is powered by VCCA.
The SN74LVC4245A device terminal out
allows the designer to switch to a normal all 3.3V or all 5V 20-terminal SN74LVC4245
device without board re-layout. The designer uses the data paths for pins 2–11 and
14–23 of the SN74LVC4245A device to align with the conventional 245 terminal
out.
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 the outputs.
This 8-bit (octal) noninverting bus
transceiver contains two separate supply rails; B port has VCCB, which is
set at 3.3V, and A port has VCCA, which is set at 5V. This allows for
translation from a 3.3V to a 5V environment, and vice versa.
The SN74LVC4245A device is designed
for asynchronous communication between data buses. The 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 are effectively isolated. The
control circuitry (DIR, OE) is powered by VCCA.
The SN74LVC4245A device terminal out
allows the designer to switch to a normal all 3.3V or all 5V 20-terminal SN74LVC4245
device without board re-layout. The designer uses the data paths for pins 2–11 and
14–23 of the SN74LVC4245A device to align with the conventional 245 terminal
out.
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 the outputs.