SN74ALS638A, SN74ALS639A, SN74AS638A, SN74AS639
OCTAL BUS TRANSCEIVERS

SDAS123A - DECEMBER 1983 - REVISED JANUARY 1995

features

• Bidirectional Bus Transceivers in High-Density 20-Pin Packages
• Choice of True or Inverting Logic
• A-Bus Outputs Are Open Collector; B-Bus Outputs Are 3 State
• Package Options Include Plastic Small-Outline (DW) Packages and Standard Plastic (N) 300-mil DIPs

description

These octal bus transceivers are designed for asynchronous two-way communication between open-collector and 3-state buses. The devices transmit data from the A bus (open-collector) to the B bus (3 state) or from the B bus to the A bus, depending on the logic level at the direction-control (DIR) input. The output-enable () input can be used to disable the device so the buses are isolated.

The -1 version of SN74ALS638A is identical to the standard version, except that the recommended maximum I_OL is increased to 48 mA.

The SN74ALS638A, SN74ALS639A, SN74AS638A, and SN74AS639 are characterized for operation from 0°C to 70°C.