SN74VMEH22501

8BIT UNIVERSAL BUS TRANSCEIVER AND TWO 1BIT BUS TRANSCEIVERS

WITH SPLIT LVTTL PORT, FEEDBACK PATH, AND 3STATE OUTPUTS

SCES357E − JULY 2001 − REVISED MARCH 2004

3

POST OFFICE BOX 655303

functional description

The SN74VMEH22501 is a high-drive (–48/64 mA), 8-bit UBT transceiver containing D-type latches and D-type

flip-flops for data-path operation in transparent, latched, or flip-flop modes. Data transmission is true logic. The

device is uniquely partitioned as 8-bit UBT transceivers with two integrated 1-bit three-wire bus transceivers.

functional description for two 1-bit bus transceivers

The OEAB inputs control the activity of the 1B or 2B port. When OEAB is high, the B-port outputs are active.

When OEAB is low, the B-port outputs are disabled.

Separate 1A and 2A inputs and 1Y and 2Y outputs provide a feedback path for control and diagnostics

monitoring. The OEBY inputs control the 1Y or 2Y outputs. When OEBY is low, the Y outputs are active. When

OEBY is high, the Y outputs are disabled.

The OEBY and OEAB inputs can be tied together to form a simple direction control where an input high yields

A data to B bus and an input low yields B data to Y bus.

1-BIT BUS TRANSCEIVER FUNCTION TABLE

INPUTS

OUTPUT

MODE

OEAB

OEBY

OUTPUT

MODE

L

H

Z

Isolation

H

H

A data to B bus

True driver

L

L

B data to Y bus

True driver

H

L

A data to B bus, B data to Y bus

True driver with feedback path