SN74ALS1645AN

Overview

The SN74ALS1645AN is an octal bus transceiver from the Texas Instruments ALS logic family, housed in a standard plastic 20-pin DIP package. It provides asynchronous two-way communication between data buses with noninverting logic and 3-state outputs. The device operates within a supply voltage range of 4.5 V to 5.5 V and supports a low-level output current of 16 mA. Propagation delays are specified between 2 ns and 15 ns depending on direction and control states. It is characterized for operation across a temperature range of 0°C to 70°C.

Feature Summary

• Provides asynchronous bidirectional data transfer between A and B buses controlled by a DIR input
• Features noninverting logic with 3-state outputs that can be disabled via OE input for bus isolation
• Designed as a lower-power alternative to SN74ALS640B and SN74ALS645A devices

Applications

• Asynchronous two-way communication between data buses
• Bus-oriented memory and command decoders
• Input/output buffering and gate drivers

Procurement Notes

Verify the specific ordering suffix 'N' corresponds to the 20-lead Plastic Dual In-Line Package (PDIP) when sourcing. Confirm RoHS compliance status and lead finish details against the latest TI packaging addendum. Ensure the application environment remains within the specified 0°C to 70°C operating temperature range and 4.5 V to 5.5 V supply voltage limits.

Selection Notes

Select this component when noninverting octal bus transceivers are required for system architecture. The ALS series offers lower power consumption compared to standard TTL equivalents while maintaining compatible speed. Consider the 20-pin PDIP form factor if through-hole mounting is necessary for the target PCB design.

Part Context

This part belongs to the SN74ALS164xA series of octal bus transceivers manufactured by Texas Instruments. It shares functional similarities with the SN74ALS1640A but utilizes noninverting logic rather than inverting logic. Both variants are designed for high-density applications using 20-pin packages.

Replacement Considerations

SN74ALS1640A (Inverting Logic)

FAQ

What is the difference between SN74ALS1645A and SN74ALS1640A?

The SN74ALS1645A features noninverting logic, whereas the SN74ALS1640A features inverting logic. Both share identical pinouts and electrical characteristics.

How does the Output Enable (OE) input function?

When the OE input is high, the device is disabled, effectively isolating the A and B buses regardless of the DIR input state.