SN74ALS667DWR

Overview

The SN74ALS667DWR is an 8-bit D-type transparent read-back latch with 3-state outputs from the Texas Instruments ALS logic family. It features inverted Q outputs and supports bus-structured applications. The device operates within a supply voltage range of 4.5 V to 5.5 V and functions at temperatures between 0°C and 70°C. Propagation delays for data inputs to outputs range from 4 ns to 20 ns. The package is a 24-pin Small-Outline (DW) plastic type.

Feature Summary

• Provides 3-state I/O-type read-back inputs allowing stored data to be routed back onto the input data bus via the OERB control signal.
• Features a bus-structured pinout designed specifically for storing contents of input data buses in bus-structured applications.
• Includes preset and clear inputs for direct control of latch states independent of the data input.

Applications

• Bus-structured memory storage applications
• Data bus content capture and read-back systems
• I/O interface buffering with bidirectional data capability

Procurement Notes

Verify the specific ordering suffix 'DWR' corresponds to the tape-and-reel packaging format rather than tube packaging, as indicated by the 'W' suffix convention in TI documentation. Confirm that the component meets RoHS compliance standards required for your assembly process. Ensure the operating temperature range of 0°C to 70°C aligns with your system's environmental specifications before finalizing procurement.

Selection Notes

Select this component when inverted output polarity is required for the SN74ALS667 architecture. Compare propagation delay characteristics against system timing requirements, noting the maximum 20 ns delay for D-to-Q transitions. Evaluate the 3-state output drive capabilities and ensure compatibility with the target bus load conditions and voltage levels defined in the electrical characteristics.

Part Context

This part belongs to the SN74ALS66x series of 8-bit latches. The SN74ALS667 variant provides inverted outputs, whereas the SN74ALS666 provides true outputs. Both share identical pinouts and functional descriptions regarding read-back capabilities. The DW package designation indicates a 24-pin Small-Outline Integrated Circuit form factor suitable for surface-mount technology.

Replacement Considerations

SN74ALS666DW serves as a functional substitute if true (non-inverted) outputs are acceptable instead of inverted ones. Verify that any replacement maintains the same ALS logic speed class and 3-state output characteristics to ensure bus compatibility.