SN74ALS243AN

Overview

The SN74ALS243AN is a quadruple bus transceiver designed for asynchronous two-way communication between data buses. It operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range from 0°C to 70°C. The device features pnp inputs that reduce dc loading on the driving circuitry. Propagation delay times are specified with maximum values of 15 ns at 4.5 V and 11 ns at 5.5 V under standard load conditions.

Feature Summary

• Dual-enable configuration allows for flexible timing control, enabling data transmission in either direction or isolating the buses.
• Simultaneous activation of both output-enable inputs creates a latch function where both sets of bus lines retain their states.
• Pnp input structure minimizes dc loading effects on the connected signal sources.

Applications

• Asynchronous two-way communication between data buses
• Bus isolation applications requiring high-impedance states
• Data storage configurations utilizing simultaneous enable inputs

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current package option addendum. The SN74ALS243AN designation corresponds to the plastic DIP package. Confirm the active status of this specific part number, as Texas Instruments may have discontinued production or updated packaging specifications for legacy logic families.

Selection Notes

Select this component when designing systems requiring bidirectional data transfer with independent control over each bus direction. The dual-output-enable architecture provides superior flexibility compared to single-enable devices. Ensure the application environment remains within the 0°C to 70°C commercial temperature limits defined for the SN74 series.

Part Context

This device belongs to the Texas Instruments ALS (Advanced Low-power Schottky) logic family. It serves as the non-inverting counterpart to the SN74ALS244A octal buffer/driver. The SN74ALS243A variant specifically addresses the need for controlled, bidirectional data flow between separate bus structures in digital systems.

Replacement Considerations

SN74ALS244A

FAQ

How does the SN74ALS243AN isolate the buses?

Isolation is achieved by setting both OEAB and OEBA inputs to a High logic level. This disables the outputs, placing the A and B ports in a high-impedance state effectively disconnecting them.

What is the function when both OEAB and OEBA are enabled?

When both output-enable inputs are Low, the device enters a latch mode. Each output reinforces its corresponding input, causing both sets of bus lines to retain their current states if no other data sources are active.