SNJ54ALS646JT

Overview

The SNJ54ALS646JT is an octal bus transceiver and register featuring 3-state outputs, manufactured by Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V and supports a maximum clock frequency of 35 MHz. The device utilizes a 24-pin Ceramic Dual In-Line Package (CDIP). Key electrical parameters include a propagation delay ranging from 5 ns to 20 ns for data paths and up to 40 ns for select control inputs. It functions over a military temperature range of -55°C to 125°C.

Feature Summary

• Integrates independent D-type flip-flops for A and B buses to enable multiplexed real-time and stored data transmission.
• Provides selectable true or inverting data paths with 3-state output capabilities controlled by OE and DIR inputs.
• Features dedicated SAB and SBA select-control inputs to manage the transition between stored and transparent data modes.

Applications

• Multiplexing real-time bus data with internally stored register data.
• Managing bidirectional data flow between two separate system buses.
• Isolating specific bus segments while maintaining internal data storage.

Procurement Notes

Verify that the ordering suffix JT corresponds to the ceramic dual in-line package configuration. Confirm the component meets the required military temperature specifications (-55°C to 125°C) for your application environment. Ensure compatibility with the 4.5 V to 5.5 V supply voltage range during system design validation.

Selection Notes

Select this component when designing systems requiring simultaneous bus isolation and data storage capabilities. It is suitable for applications needing high-speed data transfer with low power consumption characteristics typical of the ALS logic family. Consider the 24-pin CDIP package constraints for board layout and thermal management requirements.

Part Context

This device belongs to the SN54ALS646 series of octal bus transceivers and registers. It shares functional similarities with the SN54ALS648 and SN54AS646 variants, differing primarily in output polarity and speed grades. The SNJ prefix indicates a military-grade version produced under specific quality standards.

Replacement Considerations

SNJ54ALS648JT

FAQ

How does the device handle data transitions between stored and real-time modes?

The SAB and SBA select-control inputs manage the multiplexing function, eliminating typical decoding glitches that occur during transitions between stored and real-time data.

What determines the direction of data flow on the buses?

The DIR input determines which bus receives data when the output-enable (OE) signal is low, allowing control over whether data flows from Bus A to Bus B or vice versa.