SN74ALS666NT

Overview

The SN74ALS666NT is an 8-bit D-type transparent read-back latch with 3-state outputs manufactured by Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V and supports an operating temperature range of 0°C to 70°C. The device features true logic outputs, preset and clear inputs, and dual output-enable controls. Propagation delays from data input to output range from 3 ns to 18 ns depending on the transition direction.

Feature Summary

• Provides 3-state I/O-type read-back functionality allowing stored data to be routed back onto the input data bus via the OERB control pin.
• Features a bus-structured pinout designed for efficient integration into bus-structured applications.
• Includes dedicated preset and clear inputs for direct control of latch states independent of the data bus.

Applications

• Bus-structured memory storage systems
• Data bus interface circuits requiring read-back verification
• Digital logic systems utilizing 3-state buffering

Procurement Notes

Verify that the ordering suffix 'NT' corresponds to the standard plastic 300-mil DIP package as specified in the datasheet. Confirm the component meets the required 0°C to 70°C operating temperature range for your specific application environment. Ensure compatibility with the 4.5 V to 5.5 V supply voltage specifications before procurement.

Selection Notes

Select the SN74ALS666NT when true (non-inverted) logic outputs are required for 8-bit latching operations. This part is suitable for designs needing simultaneous data storage and read-back capabilities on the same bus lines. Consider the SN74ALS667 if inverted outputs are preferred instead. Verify package availability matches the target PCB footprint requirements.

Part Context

This component belongs to the SN74ALS series of high-speed TTL logic devices produced by Texas Instruments. It is functionally related to the SN74ALS667, which provides inverted outputs. Both parts share identical pinouts and electrical characteristics except for the logic polarity of the Q outputs.

Replacement Considerations

SN74ALS667DW serves as a functional substitute offering inverted outputs with identical packaging and pin configuration.